"Division by invariant integers using multiplication" paper
by Granlund and Montgomery contains a method for directly computing
divisibility (x%c == 0 for c constant) by means of the modular inverse.
The method is further elaborated in "Hacker's Delight" by Warren Section 10-17
This general rule can compute divisibilty by one multiplication and a compare
for odd divisors and an additional rotate for even divisors.
To apply the divisibility rule, we must take into account
the rules to rewrite x%c = x-((x/c)*c) and (x/c) for c constant on the first
optimization pass "opt". This complicates the matching as we want to match
only in the cases where the result of (x/c) is not also available.
So, we must match on the expanded form of (x/c) in the expression x == c*(x/c)
in the "late opt" pass after common subexpresion elimination.
Note, that if there is an intermediate opt pass introduced in the future we
could simplify these rules by delaying the magic division rewrite to "late opt"
and matching directly on (x/c) in the intermediate opt pass.
Additional rules to lower the generic RotateLeft* ops were also applied.
On amd64, the divisibility check is 25-50% faster.
name old time/op new time/op delta
DivconstI64-4 2.08ns ± 0% 2.08ns ± 1% ~ (p=0.881 n=5+5)
DivisibleconstI64-4 2.67ns ± 0% 2.67ns ± 1% ~ (p=1.000 n=5+5)
DivisibleWDivconstI64-4 2.67ns ± 0% 2.67ns ± 0% ~ (p=0.683 n=5+5)
DivconstU64-4 2.08ns ± 1% 2.08ns ± 1% ~ (p=1.000 n=5+5)
DivisibleconstU64-4 2.77ns ± 1% 1.55ns ± 2% -43.90% (p=0.008 n=5+5)
DivisibleWDivconstU64-4 2.99ns ± 1% 2.99ns ± 1% ~ (p=1.000 n=5+5)
DivconstI32-4 1.53ns ± 2% 1.53ns ± 0% ~ (p=1.000 n=5+5)
DivisibleconstI32-4 2.23ns ± 0% 2.25ns ± 3% ~ (p=0.167 n=5+5)
DivisibleWDivconstI32-4 2.27ns ± 1% 2.27ns ± 1% ~ (p=0.429 n=5+5)
DivconstU32-4 1.78ns ± 0% 1.78ns ± 1% ~ (p=1.000 n=4+5)
DivisibleconstU32-4 2.52ns ± 2% 1.26ns ± 0% -49.96% (p=0.000 n=5+4)
DivisibleWDivconstU32-4 2.63ns ± 0% 2.85ns ±10% +8.29% (p=0.016 n=4+5)
DivconstI16-4 1.54ns ± 0% 1.54ns ± 0% ~ (p=0.333 n=4+5)
DivisibleconstI16-4 2.10ns ± 0% 2.10ns ± 1% ~ (p=0.571 n=4+5)
DivisibleWDivconstI16-4 2.22ns ± 0% 2.23ns ± 1% ~ (p=0.556 n=4+5)
DivconstU16-4 1.09ns ± 0% 1.01ns ± 1% -7.74% (p=0.000 n=4+5)
DivisibleconstU16-4 1.83ns ± 0% 1.26ns ± 0% -31.52% (p=0.008 n=5+5)
DivisibleWDivconstU16-4 1.88ns ± 0% 1.89ns ± 1% ~ (p=0.365 n=5+5)
DivconstI8-4 1.54ns ± 1% 1.54ns ± 1% ~ (p=1.000 n=5+5)
DivisibleconstI8-4 2.10ns ± 0% 2.11ns ± 0% ~ (p=0.238 n=5+4)
DivisibleWDivconstI8-4 2.22ns ± 0% 2.23ns ± 2% ~ (p=0.762 n=5+5)
DivconstU8-4 0.92ns ± 1% 0.94ns ± 1% +2.65% (p=0.008 n=5+5)
DivisibleconstU8-4 1.66ns ± 0% 1.26ns ± 1% -24.28% (p=0.008 n=5+5)
DivisibleWDivconstU8-4 1.79ns ± 0% 1.80ns ± 1% ~ (p=0.079 n=4+5)
A follow-up change will address the signed division case.
Updates #30282
Change-Id: I7e995f167179aa5c76bb10fbcbeb49c520943403
Reviewed-on: https://go-review.googlesource.com/c/go/+/168037
Run-TryBot: Brian Kessler <brian.m.kessler@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
For powers of two (c=1<<k), the divisibility check x%c == 0 can be made
just by checking the trailing zeroes via a mask x&(c-1) == 0 even for signed
integers. This avoids division fix-ups when just divisibility check is needed.
To apply this rule, we match on the fixed-up version of the division. This is
neccessary because the mod and division rewrite rules are already applied
during the initial opt pass.
The speed up on amd64 due to elimination of unneccessary fix-up code is ~55%:
name old time/op new time/op delta
DivconstI64-4 2.08ns ± 0% 2.09ns ± 1% ~ (p=0.730 n=5+5)
DivisiblePow2constI64-4 1.78ns ± 1% 0.81ns ± 1% -54.66% (p=0.008 n=5+5)
DivconstU64-4 2.08ns ± 0% 2.08ns ± 0% ~ (p=0.683 n=5+5)
DivconstI32-4 1.53ns ± 0% 1.53ns ± 1% ~ (p=0.968 n=4+5)
DivisiblePow2constI32-4 1.79ns ± 1% 0.81ns ± 1% -54.97% (p=0.008 n=5+5)
DivconstU32-4 1.78ns ± 1% 1.80ns ± 2% ~ (p=0.206 n=5+5)
DivconstI16-4 1.54ns ± 2% 1.54ns ± 0% ~ (p=0.238 n=5+4)
DivisiblePow2constI16-4 1.78ns ± 0% 0.81ns ± 1% -54.72% (p=0.000 n=4+5)
DivconstU16-4 1.00ns ± 5% 1.01ns ± 1% ~ (p=0.119 n=5+5)
DivconstI8-4 1.54ns ± 0% 1.54ns ± 2% ~ (p=0.571 n=4+5)
DivisiblePow2constI8-4 1.78ns ± 0% 0.82ns ± 8% -53.71% (p=0.008 n=5+5)
DivconstU8-4 0.93ns ± 1% 0.93ns ± 1% ~ (p=0.643 n=5+5)
A follow-up CL will address the general case of x%c == 0 for signed integers.
Updates #15806
Change-Id: Iabadbbe369b6e0998c8ce85d038ebc236142e42a
Reviewed-on: https://go-review.googlesource.com/c/go/+/173557
Run-TryBot: Brian Kessler <brian.m.kessler@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
We already skipped blank field initialization in non-global contexts.
This change makes the global context treatment match.
Fixes#31546
Change-Id: I40acce49b0a9deb351ae0da098f4c114e425ec63
Reviewed-on: https://go-review.googlesource.com/c/go/+/173723
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This pair of packages caused a crash in gollvm, due to a glitch in the
way the front end handles empty/non-name parameters for functions that
are inline candidates.
Updates #31637.
Change-Id: I571c0658a00974dd36025e571638c0c836a3cdfd
Reviewed-on: https://go-review.googlesource.com/c/go/+/173617
Run-TryBot: Benny Siegert <bsiegert@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This reverts CL 168038 (git 68819fb6d2)
Reason for revert: Doesn't work on 32 bit archs.
Change-Id: Idec9098060dc65bc2f774c5383f0477f8eb63a3d
Reviewed-on: https://go-review.googlesource.com/c/go/+/173442
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
For powers of two (c=1<<k), the divisibility check x%c == 0 can be made
just by checking the trailing zeroes via a mask x&(c-1)==0 even for signed
integers. This avoids division fixups when just divisibility check is needed.
To apply this rule the generic divisibility rule for A%B = A-(A/B*B) is disabled
on the "opt" pass, but this does not affect generated code as this rule is applied
later.
The speed up on amd64 due to elimination of unneccessary fixup code is ~55%:
name old time/op new time/op delta
DivconstI64-4 2.08ns ± 0% 2.07ns ± 0% ~ (p=0.079 n=5+5)
DivisiblePow2constI64-4 1.78ns ± 1% 0.81ns ± 1% -54.55% (p=0.008 n=5+5)
DivconstU64-4 2.08ns ± 0% 2.08ns ± 0% ~ (p=1.000 n=5+5)
DivconstI32-4 1.53ns ± 0% 1.53ns ± 0% ~ (all equal)
DivisiblePow2constI32-4 1.79ns ± 1% 0.81ns ± 4% -54.75% (p=0.008 n=5+5)
DivconstU32-4 1.78ns ± 1% 1.78ns ± 1% ~ (p=1.000 n=5+5)
DivconstI16-4 1.54ns ± 2% 1.53ns ± 0% ~ (p=0.333 n=5+4)
DivisiblePow2constI16-4 1.78ns ± 0% 0.79ns ± 1% -55.39% (p=0.000 n=4+5)
DivconstU16-4 1.00ns ± 5% 0.99ns ± 1% ~ (p=0.730 n=5+5)
DivconstI8-4 1.54ns ± 0% 1.53ns ± 0% ~ (p=0.714 n=4+5)
DivisiblePow2constI8-4 1.78ns ± 0% 0.80ns ± 0% -55.06% (p=0.000 n=5+4)
DivconstU8-4 0.93ns ± 1% 0.95ns ± 1% +1.72% (p=0.024 n=5+5)
A follow-up CL will address the general case of x%c == 0 for signed integers.
Updates #15806
Change-Id: I0d284863774b1bc8c4ce87443bbaec6103e14ef4
Reviewed-on: https://go-review.googlesource.com/c/go/+/168038
Reviewed-by: Keith Randall <khr@golang.org>
In 31618, we end up comparing the is-stmt-ness of positions
to repurpose real instructions as inline marks. If the is-stmt-ness
doesn't match, we end up not being able to remove the inline mark.
Always use statement-full positions to do the matching, so we
always find a match if there is one.
Also always use positions that are statements for inline marks.
Fixes#31618
Change-Id: Idaf39bdb32fa45238d5cd52973cadf4504f947d5
Reviewed-on: https://go-review.googlesource.com/c/go/+/173324
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Stack object generation code was always using the local package name
for its symbol. Normally that doesn't matter, as we usually only
compile functions in the local package. But for wrappers, the compiler
generates functions which live in other packages. When there are two
other packages with identical functions to wrap, the same name appears
twice, and the compiler goes boom.
Fixes#31252
Change-Id: I7026eebabe562cb159b8b6046cf656afd336ba25
Reviewed-on: https://go-review.googlesource.com/c/go/+/171464
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
The special case logic for go/defer arguments in Escape.call was
scattered around a bit and was somewhat inconsistently handled across
different types of function calls and parameters. This CL pulls the
logic out into a separate callStmt method that's used uniformly for
all kinds of function calls and arguments.
Fixes#31573.
Change-Id: Icdcdf611754dc3fcf1af7cb52879fb4b73a7a31f
Reviewed-on: https://go-review.googlesource.com/c/go/+/173019
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
A check in inl.go to prevent inlining of functions calling
either getcallerpc or getcallersp does not work when these
functions are intrinsics. Swap checks to fix.
Includes test.
No bug, this was discovered in the course of a ridiculous
experiment with inlining.
Change-Id: Ie1392523bb89882d586678f2674e1a4eadc5e431
Reviewed-on: https://go-review.googlesource.com/c/go/+/172217
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Casp1 is implemented in Go on js/wasm, so escape analysis correctly
determines that the "old" parameter does not escape (which is good).
Unfortunately, test/run.go doesn't have a way to indicate that ERROR
messages are optional, and cmd/compile only emits diagnostics for "var
x int" when it's moved to the heap; not when it stays on the stack.
To accomodate that this test currently passes on some GOARCHes but not
others, rewrite the Casp1 test to use "x := new(int)" and allow both
"new(int) escapes to heap" or "new(int) does not escape".
Updates #31525.
Change-Id: I40150a7ff9042f184386ccdb2d4d428f63e8ba4f
Reviewed-on: https://go-review.googlesource.com/c/go/+/172602
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The //go:noescape directive says that arguments don't leak at all,
which is too aggressive of a claim for functions that return pointers
derived from their parameters.
Remove the directive for now. Long term fix will require a new
directive that allows more fine-grained control over escape analysis
information supplied for functions implemented in assembly.
Also, update the BAD comments in the test cases for Loadp: we really
want that *ptr leaks to the result parameter, not that *ptr leaks to
the heap.
Updates #31525.
Change-Id: Ibfa61f2b70daa7ed3223056b57eeee777eef2e31
Reviewed-on: https://go-review.googlesource.com/c/go/+/172578
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Cherry pointed out this case in review for CL 136496. That CL was
slightly too aggressive, and I likely would have made the same mistake
if I tried it myself.
Updates #27772.
Change-Id: I1fafabb9f8d9aba0494aa71333a4e17cf1bac5c8
Reviewed-on: https://go-review.googlesource.com/c/go/+/172421
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
There weren't any tests to make sure these work correctly, and this
led to escape analysis regressions in both linux/s390x and js/wasm.
The underlying issue that cmd/compile is only getting some of these
correct because escape analysis doesn't understand //go:linkname is
still present, but at least this addresses the fragility aspect.
Updates #15283.
Change-Id: I546aee1899d098b2e3de45e9b33c3ca22de485f8
Reviewed-on: https://go-review.googlesource.com/c/go/+/172420
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
In typecheckclosure, a xfunc node will be put to xtop. But that node can
be shared between multiple closures, like in a const declaration group:
const (
x = unsafe.Sizeof(func() {})
y
)
It makes a xfunc node appears multiple times in xtop, causing duplicate
initLSym run.
To fix this issue, we only do typecheck for xfunc one time, and setup
closure node earlier in typecheckclosure process.
Fixes#30709
Change-Id: Ic924a157ee9f3e5d776214bef5390849ddc8aab9
Reviewed-on: https://go-review.googlesource.com/c/go/+/172298
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The new escape analysis implementation tries to emit debugging
diagnostics that are compatible with the existing implementation, but
there's a handful of cases that are easier to handle by updating the
test expectations instead.
For regress tests that need updating, the original file is copied to
oldescapeXXX.go.go with -newescape=false added to the //errorcheck
line, while the file is updated in place with -newescape=true and new
test requirements.
Notable test changes:
1) escape_because.go looks for a lot of detailed internal debugging
messages that are fairly particular to how esc.go works and that I
haven't attempted to port over to escape.go yet.
2) There are a lot of "leaking param: x to result ~r1 level=-1"
messages for code like
func(p *int) *T { return &T{p} }
that were simply wrong. Here &T must be heap allocated unconditionally
(because it's being returned); and since p is stored into it, p
escapes unconditionally too. esc.go incorrectly reports that p escapes
conditionally only if the returned pointer escaped.
3) esc.go used to print each "leaking param" analysis result as it
discovered them, which could lead to redundant messages (e.g., that a
param leaks at level=0 and level=1). escape.go instead prints
everything at the end, once it knows the shortest path to each sink.
4) esc.go didn't precisely model direct-interface types, resulting in
some values unnecessarily escaping to the heap when stored into
non-escaping interface values.
5) For functions written in assembly, esc.go only printed "does not
escape" messages, whereas escape.go prints "does not escape" or
"leaking param" as appropriate, consistent with the behavior for
functions written in Go.
6) 12 tests included "BAD" annotations identifying cases where esc.go
was unnecessarily heap allocating something. These are all fixed by
escape.go.
Updates #23109.
Change-Id: Iabc9eb14c94c9cadde3b183478d1fd54f013502f
Reviewed-on: https://go-review.googlesource.com/c/go/+/170447
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
For a failed interface conversion not in ",ok" form, getitab
calls itab.init to get the name of the missing method for the
panic message. itab.init will try to find the methods, populate
the method table as it goes. When some method is missing, it sets
itab.fun[0] to 0 before return. There is a small window that
itab.fun[0] could be non-zero.
If concurrently, another goroutine tries to do the same interface
conversion, it will read the same itab's fun[0]. If this happens
in the small window, it sees a non-zero fun[0] and thinks the
conversion succeeded, which is bad.
Fix the race by setting fun[0] to non-zero only when we know the
conversion succeeds. While here, also simplify the syntax
slightly.
Fixes#31419.
Change-Id: Ied34d3043079eb933e330c5877b85e13f98f1916
Reviewed-on: https://go-review.googlesource.com/c/go/+/171759
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
These new calls should not prevent NOSPLIT promotion, like the old ones.
These new calls should not prevent racefuncenter/exit removal.
(The latter was already true, as the new calls are not yet lowered
to StaticCalls at the point where racefuncenter/exit removal is done.)
Add tests to make sure we don't regress (again).
Fixes#31219
Change-Id: I3fb6b17cdd32c425829f1e2498defa813a5a9ace
Reviewed-on: https://go-review.googlesource.com/c/go/+/170639
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>
Some var declarations return "extra expression" or "missing expression"
errors when they should return “assignment mismatch” instead. Change
the returned error messages to exhibit the desired behavior.
Fixes#30085.
Change-Id: I7189355fbb0f976d70100779db4f81a9ae64fb11
Reviewed-on: https://go-review.googlesource.com/c/go/+/161558
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
"leaking closure reference" is redundant for similar reasons as "&x
escapes to heap" for OADDR nodes: the reference itself does not
allocate, and we already report when the referenced variable is moved
to heap.
"mark escaped content" is redundant with "leaking param content".
Updates #23109.
Change-Id: I1ab599cb1e8434f1918dd80596a70cba7dc8a0cf
Reviewed-on: https://go-review.googlesource.com/c/go/+/170321
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
For most nodes (e.g., OPTRLIT, OMAKESLICE, OCONVIFACE), escape
analysis prints "escapes to heap" or "does not escape" to indicate
whether that node's allocation can be heap or stack allocated.
These messages are also emitted for OADDR, even though OADDR does not
actually allocate anything itself. Moreover, it's redundant because
escape analysis already prints "moved to heap" diagnostics when an
OADDR node like "&x" causes x to require heap allocation.
Because OADDR nodes don't allocate memory, my escape analysis rewrite
doesn't naturally emit the "escapes to heap" / "does not escape"
diagnostics for them. It's also non-trivial to replicate the exact
semantics esc.go uses for OADDR.
Since there are so many of these messages, I'm disabling them in this
CL by themselves. I modified esc.go to suppress the Warnl calls
without any other behavior changes, and then used a shell script to
automatically remove any ERROR messages mentioned by run.go in
"missing error" or "no match for" lines.
Fixes#16300.
Updates #23109.
Change-Id: I3993e2743c3ff83ccd0893f4e73b366ff8871a57
Reviewed-on: https://go-review.googlesource.com/c/go/+/170319
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
The bug in 29612 is that there are two similar-looking anonymous interface
types in two different packages, ./p1/ssa and ./p2/ssa:
v.(interface{ foo() }).foo()
These types should be treated differently because the unexported method
makes the types different (according to the spec).
But when generating the type descriptors for those two types, they
both have the name "interface { ssa.foo() }". They thus get the same
symbol, and the linker happily unifies them. It picks an arbitrary one
for the runtime to use, but that breaks conversions from concrete types
that have a foo method from the package which had its interface type
overwritten.
We need to encode the metadata symbol for unexported methods as package
path qualified (The same as we did in CL 27791 for struct fields).
So switching from FmtUnsigned to Fmtleft by default fixes the issue.
In case of generating namedata, FmtUnsigned is used.
The benchmark result ends up in no significant change of compiled binary
compare to the immediate parent.
Fixes#29612
Change-Id: I775aff91ae4a1bb16eb18a48d55e3b606f3f3352
Reviewed-on: https://go-review.googlesource.com/c/go/+/170157
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
When branching at a bounds check for indexing or slicing ops, prove currently
only learns from the upper bound. On the positive branch, we currently learn
i < len(a) (or i <= len(a)) in both the signed and unsigned domains.
This CL makes prove also learn from the lower bound. Specifically, on the
positive branch from index or slicing ops, prove will now ALSO learn i >= 0 in
the signed domain (this fact is of no value in the unsigned domain).
The substantive change itself is only an additional call to addRestrictions,
though I've also inverted the nested switch statements around that call for the
sake of clarity.
This CL removes 92 bounds checks from std and cmd. It passes all tests and
shows no deltas on compilecmp.
Fixes#28885
Change-Id: I13eccc36e640eb599fa6dc5aa3be3c7d7abd2d9e
Reviewed-on: https://go-review.googlesource.com/c/go/+/170121
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Giovanni Bajo <rasky@develer.com>
Would suggest extending capabilities (32-bit, unsigned, etc)
in separate CLs because prove bugs are so mystifying.
This implements the suggestion in this comment
https://go-review.googlesource.com/c/go/+/104041/10/src/cmd/compile/internal/ssa/loopbce.go#164
for inferring properly bounded iteration for loops of the form
for i := K0; i < KNN-(K-1); i += K
for i := K0; i <= KNN-K; i += K
Where KNN is "known non negative" (i.e., len or cap) and K
is also not negative. Because i <= KNN-K, i+K <= KNN and
no overflow occurs.
Also handles decreasing case (K1 > 0)
for i := KNN; i >= K0; i -= K1
which works when MININT+K1 < K0
(i.e. MININT < K0-K1, no overflow)
Signed only, also only 64 bit for now.
Change-Id: I5da6015aba2f781ec76c4ad59c9c48d952325fdc
Reviewed-on: https://go-review.googlesource.com/c/go/+/136375
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alexandru Moșoi <alexandru@mosoi.ro>
Prove currently fails to remove bounds checks of the form:
if i >= 0 { // hint that i is non-negative
for i < len(data) { // i becomes Phi in the loop SSA
_ = data[i] // data[Phi]; bounds check!!
i++
}
}
addIndVarRestrictions fails to identify that the loop induction
variable, (Phi), is non-negative. As a result, the restrictions,
i <= Phi < len(data), are only added for the signed domain. When
testing the bounds check, addBranchRestrictions is similarly unable
to infer that Phi is non-negative. As a result, the restriction,
Phi >= len(data), is only added/tested for the unsigned domain.
This CL changes the isNonNegative method to utilise the factTable's
partially ordered set (poset). It also adds field factTable.zero to
allow isNonNegative to query the poset using the zero(0) constant
found or created early in prove.
Fixes#28956
Change-Id: I792f886c652eeaa339b0d57d5faefbf5922fe44f
Reviewed-on: https://go-review.googlesource.com/c/go/+/161437
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Giovanni Bajo <rasky@develer.com>
Typechecking treats all untyped numbers as integers for the purposes
of validating operators. However, when I refactoring constant
operation evalution in golang.org/cl/139901, I mistakenly interpreted
that the only invalid case that needed to be preserved was % (modulo)
on floating-point values.
This CL restores the other remaining cases that were dropped from that
CL. It also uses the phrasing "invalid operation" instead of "illegal
constant expression" for better consistency with the rest of
cmd/compile and with go/types.
Lastly, this CL extends setconst to recognize failed constant folding
(e.g., division by zero) so that we can properly mark those
expressions as broken rather than continuing forward with bogus values
that might lead to further spurious errors.
Fixes#31060.
Change-Id: I1ab6491371925e22bc8b95649f1a0eed010abca6
Reviewed-on: https://go-review.googlesource.com/c/go/+/169719
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Update the issue 30908 test to work with the no-opt builder
(this requires a corresponding change in the linker as well).
As part of this change, 'rundir' tests are now linked without
passing "-w" to the linker.
Updates #30908.
Fixes#31034.
Change-Id: Ic776e1607075c295e409e1c8230aaf55a79a6323
Reviewed-on: https://go-review.googlesource.com/c/go/+/169161
Reviewed-by: Ian Lance Taylor <iant@golang.org>
CL 135377 introduces pass strings and slices to convT2{E,I} by value.
Before that CL, all types, except interface will be allocated temporary
address. The CL changes the logic that only constant and type which
needs address (determine by convFuncName) will be allocated.
It fails to cover the case where type is static composite literal.
Adding condition to check that case fixes the issue.
Also, static composite literal node implies constant type, so consttype
checking can be removed.
Fixes#30956
Change-Id: Ifc750a029fb4889c2d06e73e44bf85e6ef4ce881
Reviewed-on: https://go-review.googlesource.com/c/go/+/168858
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Some special-case code paths in order.go didn't expect OCALLFUNC to
have Ninit; in particular, OAS2FUNC and ODEFER/OGO failed to call
o.init on their child OCALLFUNC node. This resulted in not all of the
AST being properly ordered.
This was noticed because order is responsible for introducing an
invariant around how OAPPEND is used, which is enforced by walk.
However, there were perhaps simpler cases (e.g., simple order of
evaluation) that were being silently miscompiled.
Fixes#31010.
Change-Id: Ib928890ab5ec2aebd8e30a030bc2b404387f9123
Reviewed-on: https://go-review.googlesource.com/c/go/+/169257
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
New test case designed to mimic the code in issue 30908, which
features duplicate but non-indentical DWARF abstract subprogram DIEs.
Updates #30908.
Change-Id: Iacb4b53e6a988e46c801cdac236cef883c553f8f
Reviewed-on: https://go-review.googlesource.com/c/go/+/168957
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
For "rundir" tests, allow users to add in linker flags as well as
compiler flags, e.g.
// rundir -m -ldflags -w
The directive above will pass "-m" to the compiler on each package compilation
and "-w" to the linker for the final link.
In addition, if "-P" is specified with 'rundir', then for each compile
pass in "-p <X>" to set the packagepath explicitly, which is closer to
how the compiler is run by 'go build'.
Change-Id: I04720011a89d1bd8dcb4f2ccb4af1d74f6a01da1
Reviewed-on: https://go-review.googlesource.com/c/go/+/168977
Reviewed-by: Cherry Zhang <cherryyz@google.com>
It is possible that a "volatile" value (one that can be clobbered
by preparing args of a call) to be used in multiple write barrier
calls. We used to copy the volatile value right before each call.
But this doesn't work if the value is used the second time, after
the first call where it is already clobbered. Copy it before
emitting any call.
Fixes#30977.
Change-Id: Iedcc91ad848d5ded547bf37a8359c125d32e994c
Reviewed-on: https://go-review.googlesource.com/c/go/+/168677
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This CL instrinsifies Add64 with arm64 instruction sequence ADDS, ADCS
and ADC, and optimzes the case of carry chains.The CL also changes the
test code so that the intrinsic implementation can be tested.
Benchmarks:
name old time/op new time/op delta
Add-224 2.500000ns +- 0% 2.090000ns +- 4% -16.40% (p=0.000 n=9+10)
Add32-224 2.500000ns +- 0% 2.500000ns +- 0% ~ (all equal)
Add64-224 2.500000ns +- 0% 1.577778ns +- 2% -36.89% (p=0.000 n=10+9)
Add64multiple-224 6.000000ns +- 0% 2.000000ns +- 0% -66.67% (p=0.000 n=10+10)
Change-Id: I6ee91c9a85c16cc72ade5fd94868c579f16c7615
Reviewed-on: https://go-review.googlesource.com/c/go/+/159017
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
'SUBQ $-0x80, r' is shorter to encode than 'ADDQ $0x80, r',
and functionally equivalent. Use it instead.
Shaves off a few bytes here and there:
file before after Δ %
compile 25935856 25927664 -8192 -0.032%
nm 4251840 4247744 -4096 -0.096%
Change-Id: Ia9e02ea38cbded6a52a613b92e3a914f878d931e
Reviewed-on: https://go-review.googlesource.com/c/go/+/168344
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
When initializing a new object, we're often writing
1) to a location that doesn't have a pointer to a heap object
2) a pointer that doesn't point to a heap object
When both those conditions are true, we can avoid the write barrier.
This CL detects case 1 by looking for writes to known-zeroed
locations. The results of runtime.newobject are zeroed, and we
perform a simple tracking of which parts of that object are written so
we can determine what part remains zero at each write.
This CL detects case 2 by looking for addresses of globals (including
the types and itabs which are used in interfaces) and for nil pointers.
Makes cmd/go 0.3% smaller. Some particular cases, like the slice
literal in #29573, can get much smaller.
TODO: we can remove actual zero writes also with this mechanism.
Update #29573
Change-Id: Ie74a3533775ea88da0495ba02458391e5db26cb9
Reviewed-on: https://go-review.googlesource.com/c/go/+/156363
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
The name change init -> init.ializers was initially required for
initialization code.
With CL 161337 there's no wrapper code any more, there's a data
structure instead (named .inittask). So we can go back to just
plain init appearing in tracebacks.
RELNOTE=yes
Update #29919. Followon to CL 161337.
Change-Id: I5a4a49d286df24b53b2baa193dfda482f3ea82a5
Reviewed-on: https://go-review.googlesource.com/c/go/+/167780
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Instead of writing an init function per package that does the same
thing for every package, just write that implementation once in the
runtime. Change the compiler to generate a data structure that encodes
the required initialization operations.
Reduces cmd/go binary size by 0.3%+. Most of the init code is gone,
including all the corresponding stack map info. The .inittask
structures that replace them are quite a bit smaller.
Most usefully to me, there is no longer an init function in every -S output.
(There is an .inittask global there, but it's much less distracting.)
After this CL we could change the name of the "init.ializers" function
back to just "init".
Update #6853
R=go1.13
Change-Id: Iec82b205cc52fe3ade4d36406933c97dbc9c01b1
Reviewed-on: https://go-review.googlesource.com/c/go/+/161337
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
golang.org/cl/166983 started serializing the Ninit field of OCALL
nodes within function inline bodies (necessary to fix a regression in
building crypto/ecdsa with -gcflags=-l=4), but this means the Ninit
field needs to be typechecked when the imported function body is used.
It's unclear why this wasn't necessary for the crypto/ecdsa
regression.
Fixes#30907.
Change-Id: Id5f0bf3c4d17bbd6d5318913b859093c93a0a20c
Reviewed-on: https://go-review.googlesource.com/c/go/+/168199
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
A few examples (for accessing a slice of length 3):
s[-1] runtime error: index out of range [-1]
s[3] runtime error: index out of range [3] with length 3
s[-1:0] runtime error: slice bounds out of range [-1:]
s[3:0] runtime error: slice bounds out of range [3:0]
s[3:-1] runtime error: slice bounds out of range [:-1]
s[3:4] runtime error: slice bounds out of range [:4] with capacity 3
s[0:3:4] runtime error: slice bounds out of range [::4] with capacity 3
Note that in cases where there are multiple things wrong with the
indexes (e.g. s[3:-1]), we report one of those errors kind of
arbitrarily, currently the rightmost one.
An exhaustive set of examples is in issue30116[u].out in the CL.
The message text has the same prefix as the old message text. That
leads to slightly awkward phrasing but hopefully minimizes the chance
that code depending on the error text will break.
Increases the size of the go binary by 0.5% (amd64). The panic functions
take arguments in registers in order to keep the size of the compiled code
as small as possible.
Fixes#30116
Change-Id: Idb99a827b7888822ca34c240eca87b7e44a04fdd
Reviewed-on: https://go-review.googlesource.com/c/go/+/161477
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
This is a re-attempt at CL 153841, which caused two regressions:
1. crypto/ecdsa failed to build with -gcflags=-l=4. This was because
when "t1, t2, ... := g(); f(t1, t2, ...)" was exported, we were losing
the first assignment from the call's Ninit field.
2. net/http/pprof failed to run with -gcflags=-N. This is due to a
conflict with CL 159717: as of that CL, package-scope initialization
statements are executed within the "init.ializer" function, rather
than the "init" function, and the generated temp variables need to be
moved accordingly too.
[Rest of description is as before.]
This CL moves order.go's copyRet logic for rewriting f(g()) into t1,
t2, ... := g(); f(t1, t2, ...) earlier into typecheck. This allows the
rest of the compiler to stop worrying about multi-value functions
appearing outside of OAS2FUNC nodes.
This changes compiler behavior in a few observable ways:
1. Typechecking error messages for builtin functions now use general
case error messages rather than unnecessarily differing ones.
2. Because f(g()) is rewritten before inlining, saved inline bodies
now see the rewritten form too. This could be addressed, but doesn't
seem worthwhile.
3. Most notably, this simplifies escape analysis and fixes a memory
corruption issue in esc.go. See #29197 for details.
Fixes#15992.
Fixes#29197.
Change-Id: I930b10f7e27af68a0944d6c9bfc8707c3fab27a4
Reviewed-on: https://go-review.googlesource.com/c/go/+/166983
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
We know that a & 31 is non-negative for all a, signed or not.
We can avoid checking that and needing to write out an
unreachable call to panicshift.
Change-Id: I32f32fb2c950d2b2b35ac5c0e99b7b2dbd47f917
Reviewed-on: https://go-review.googlesource.com/c/go/+/167499
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
The only ways to construct an OLITERAL node are (1) a basic literal
from the source package, (2) constant folding within evconst (which
only folds Go language constants), (3) the universal "nil" constant,
and (4) implicit conversions of nil to some concrete type.
Passes toolstash-check.
Change-Id: I30fc6b07ebede7adbdfa4ed562436cbb7078a2ff
Reviewed-on: https://go-review.googlesource.com/c/go/+/166981
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
ppc64{,le} processor level selection allows the compiler to generate instructions
targeting newer processors and processor-specific optimizations without breaking
compatibility with our current baseline. This feature introduces a new environment
variable, GOPPC64.
GOPPC64 is a GOARCH=ppc64{,le} specific option, for a choice between different
processor levels (i.e. Instruction Set Architecture versions) for which the
compiler will target. The default is 'power8'.
Change-Id: Ic152e283ae1c47084ece4346fa002a3eabb3bb9e
Reviewed-on: https://go-review.googlesource.com/c/go/+/163758
Run-TryBot: Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
This test invokes 'go build', so in module mode it needs a module
cache to guard edits to go.mod.
Fixes#30776
Change-Id: I89ebef1fad718247e7f972cd830e31d6f4a83e4c
Reviewed-on: https://go-review.googlesource.com/c/go/+/167085
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The CL 164718 adds new condition flags for floating-point comparisons
in arm64 backend, but dose not add the handling in rewrite.go for
corresponding Ops, which causes issue 30679. And this CL fixes this
issue.
Fixes#30679
Change-Id: I8acc749f78227c3e9e74fa7938f05fb442fb62c6
Reviewed-on: https://go-review.googlesource.com/c/go/+/166579
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
New test for issue 30659 (compilation error due to bad
export data).
Updates #30659.
Change-Id: I2541ee3c379e5b22033fea66bb4ebaf720cc5e1f
Reviewed-on: https://go-review.googlesource.com/c/go/+/166917
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Two tests (load_le_byte8_uint64_inv and load_be_byte8_uint64)
pass but the generated code isn't actually correct.
The test regexp provides a false negative, as it matches the
MOVQ (SP), BP instruction in the epilogue.
Combined loads never worked for these cases - the test was added in error
as part of a batch and not noticed because of the above false match.
Normalize the amd64/386 tests to always negative match on narrower
loads and OR.
Change-Id: I256861924774d39db0e65723866c81df5ab5076f
Reviewed-on: https://go-review.googlesource.com/c/go/+/166837
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Using Once.Do is now extremely cheap because the fast path is just an inlined
atomic load of a variable that is written only once and a conditional jump.
This is very beneficial for Once.Do because, due to its nature, the fast path
will be used for every call after the first one.
In a attempt to mimize code size increase, reorder the fields so that the
pointer to Once is also the pointer to Once.done, that is the only field used
in the hot path. This allows to use more compact instruction encodings or less
instructions in the hot path (that is inlined at every callsite).
name old time/op new time/op delta
Once 4.54ns ± 0% 2.06ns ± 0% -54.59% (p=0.000 n=19+16)
Once-4 1.18ns ± 0% 0.55ns ± 0% -53.39% (p=0.000 n=15+16)
Once-16 0.53ns ± 0% 0.17ns ± 0% -67.92% (p=0.000 n=18+17)
linux/amd64 bin/go 14675861 (previous commit 14663387, +12474/+0.09%)
Change-Id: Ie2708103ab473787875d66746d2f20f1d90a6916
Reviewed-on: https://go-review.googlesource.com/c/go/+/152697
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Turns out this makes the fix for 28797 unnecessary, because this order
ensures that the RHS of IsSliceInBounds ops are always nonnegative.
The real reason for this change is that it also makes dealing with
<0 values easier for reporting values in bounds check panics (issue #30116).
Makes cmd/go negligibly smaller.
Update #28797
Change-Id: I1f25ba6d2b3b3d4a72df3105828aa0a4b629ce85
Reviewed-on: https://go-review.googlesource.com/c/go/+/166377
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Current compiler reverses operands to work around NaN in
"less than" and "less equal than" comparisons. But if we
want to use "FCMPD/FCMPS $(0.0), Fn" to do some optimization,
the workaround way does not work. Because assembler does
not support instruction "FCMPD/FCMPS Fn, $(0.0)".
This CL sets condition flags for floating-point comparisons
to resolve this problem.
Change-Id: Ia48076a1da95da64596d6e68304018cb301ebe33
Reviewed-on: https://go-review.googlesource.com/c/go/+/164718
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Update the test in test/heapsampling.go to more thoroughly validate heap sampling.
Lower the sampling rate on the test to ensure allocations both smaller and
larger than the sampling rate are tested.
Tighten up the validation check to a 10% difference between the unsampled and correct value.
Because of the nature of random sampling, it is possible that the unsampled value fluctuates
over that range. To avoid flakes, run the experiment three times and only report an issue if the
same location consistently falls out of range on all experiments.
This tests the sampling fix in cl/158337.
Change-Id: I54a709e5c75827b8b1c2d87cdfb425ab09759677
GitHub-Last-Rev: 7c04f12603
GitHub-Pull-Request: golang/go#26944
Reviewed-on: https://go-review.googlesource.com/c/go/+/129117
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This CL adds two rules to turn patterns like ((x<<8) | (x>>8)) (the type of
x is uint16, "|" can also be "+" or "^") to a REV16 instruction on arm v6+.
This optimization rule can be used for math/bits.ReverseBytes16.
Benchmarks on arm v6:
name old time/op new time/op delta
ReverseBytes-32 2.86ns ± 0% 2.86ns ± 0% ~ (all equal)
ReverseBytes16-32 2.86ns ± 0% 2.86ns ± 0% ~ (all equal)
ReverseBytes32-32 1.29ns ± 0% 1.29ns ± 0% ~ (all equal)
ReverseBytes64-32 1.43ns ± 0% 1.43ns ± 0% ~ (all equal)
Change-Id: I819e633c9a9d308f8e476fb0c82d73fb73dd019f
Reviewed-on: https://go-review.googlesource.com/c/go/+/159019
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
First the insidious bug:
var n uintptr
for n := elemPtrs; n > 120; n -= 120 {
prog = append(prog, 120)
prog = append(prog, mask[:15]...)
mask = mask[15:]
}
prog = append(prog, byte(n))
prog = append(prog, mask[:(n+7)/8]...)
The := breaks this code, because the n after the loop is always 0!
We also do need to handle field padding correctly. In particular
the old padding code doesn't correctly handle fields that are not
a multiple of a pointer in size.
Fixes#30606.
Change-Id: Ifcab9494dc25c20116753c5d7e0145d6c2053ed8
Reviewed-on: https://go-review.googlesource.com/c/go/+/165860
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
They are missing a stop byte at the end.
Normally this doesn't matter, but when including a GC program
in another GC program, we strip the last byte. If that last byte
wasn't a stop byte, then we've thrown away part of the program
we actually need.
Fixes#30606
Change-Id: Ie9604beeb84f7f9442e77d31fe64c374ca132cce
Reviewed-on: https://go-review.googlesource.com/c/go/+/165857
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Make sure the side effects inside short-circuited operations (&& and ||)
happen correctly.
Before this CL, we attached the side effects to the node itself using
exprInPlace. That caused other side effects in sibling expressions
to get reordered with respect to the short circuit side effect.
Instead, rewrite a && b like:
r := a
if r {
r = b
}
That code we can keep correctly ordered with respect to other
side-effects extracted from part of a big expression.
exprInPlace seems generally unsafe. But this was the only case where
exprInPlace is called not at the top level of an expression, so I
don't think the other uses can actually trigger an issue (there can't
be a sibling expression). TODO: maybe those cases don't need "in
place", and we can retire that function generally.
This CL needed a small tweak to the SSA generation of OIF so that the
short circuit optimization still triggers. The short circuit optimization
looks for triangle but not diamonds, so don't bother allocating a block
if it will be empty.
Go 1 benchmarks are in the noise.
Fixes#30566
Change-Id: I19c04296bea63cbd6ad05f87a63b005029123610
Reviewed-on: https://go-review.googlesource.com/c/go/+/165617
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
cmd/dist executes 'go test' within this directory, so it needs a
go.mod file to tell the compiler what package path to use in
diagnostic and debug information.
Updates #30228
Change-Id: Ia313ac06bc0ec4631d415faa20c56cce2ac8dbc5
Reviewed-on: https://go-review.googlesource.com/c/go/+/165498
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Fix builder breakage from CL 148958.
This is an inlining test that should be skipped on -N -l.
The inlining also doesn't happen on arm and wasm, so skip the test
there too.
Fixes the noopt builder, the linux-arm builder, and the wasm builder.
Updates #30605
Change-Id: I06b90d595be7185df61db039dd225dc90d6f678f
Reviewed-on: https://go-review.googlesource.com/c/go/+/165339
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Currently, runtime.KeepAlive applied on a stack object doesn't
actually keeps the stack object alive, and the heap object
referenced from it could be collected. This is because the
address of the stack object is rematerializeable, and we just
ignored KeepAlive on rematerializeable values. This CL fixes it.
Fixes#30476.
Change-Id: Ic1f75ee54ed94ea79bd46a8ddcd9e81d01556d1d
Reviewed-on: https://go-review.googlesource.com/c/164537
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This CL moves order.go's copyRet logic for rewriting f(g()) into t1,
t2, ... = g(); f(t1, t2, ...) earlier into typecheck. This allows the
rest of the compiler to stop worrying about multi-value functions
appearing outside of OAS2FUNC nodes.
This changes compiler behavior in a few observable ways:
1. Typechecking error messages for builtin functions now use general
case error messages rather than unnecessarily differing ones.
2. Because f(g()) is rewritten before inlining, saved inline bodies
now see the rewritten form too. This could be addressed, but doesn't
seem worthwhile.
3. Most notably, this simplifies escape analysis and fixes a memory
corruption issue in esc.go. See #29197 for details.
Fixes#15992.
Fixes#29197.
Change-Id: I86a70668301efeec8fbd11fe2d242e359a3ad0af
Reviewed-on: https://go-review.googlesource.com/c/153841
Reviewed-by: Robert Griesemer <gri@golang.org>
isGoConst could spuriously return true for variables that shadow a
constant declaration with the same name.
Because even named constants are always represented by OLITERAL nodes,
the easy fix is to just ignore ONAME nodes in isGoConst. We can
similarly ignore ONONAME nodes.
Confirmed that k8s.io/kubernetes/test/e2e/storage builds again with
this fix.
Fixes#30430.
Change-Id: I899400d749982d341dc248a7cd5a18277c2795ec
Reviewed-on: https://go-review.googlesource.com/c/164319
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
If a type switch case expression has failed typechecking, the case body is
likely to also fail with confusing or spurious errors. Suppress
typechecking the case body when this happens.
Fixes#28926
Change-Id: Idfdb9d5627994f2fd90154af1659e9a92bf692c4
Reviewed-on: https://go-review.googlesource.com/c/158617
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Consistent logic for handling both duplicate map keys and case values,
and eliminates ad hoc value hashing code.
Also makes cmd/compile consistent with go/types's handling of
duplicate constants (see #28085), which is at least an improvement
over the status quo even if we settle on something different for the
spec.
As a side effect, this also suppresses cmd/compile's warnings about
duplicate nils in (non-interface expression) switch statements, which
was technically never allowed by the spec anyway.
Updates #28085.
Updates #28378.
Change-Id: I176a251e770c3c5bc11c2bf8d1d862db8f252a17
Reviewed-on: https://go-review.googlesource.com/c/152544
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Emit &runtime.zerobase instead of a call to newobject for
allocations of zero sized objects in walk.go.
Fixes#29446
Change-Id: I11b67981d55009726a17c2e582c12ce0c258682e
Reviewed-on: https://go-review.googlesource.com/c/155840
Run-TryBot: Iskander Sharipov <quasilyte@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
var a []int = ...
p := &a[0]
_ = *p
We don't need to nil check on the 3rd line. If the bounds check on the 2nd
line passes, we know p is non-nil.
We rely on the fact that any cap>0 slice has a non-nil pointer as its
pointer to the backing array. This is true for all safely-constructed slices,
and I don't see any reason why someone would violate this rule using unsafe.
R=go1.13
Fixes#30366
Change-Id: I3ed764fcb72cfe1fbf963d8c1a82e24e3b6dead7
Reviewed-on: https://go-review.googlesource.com/c/163740
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
When looking for the field specified in a composite literal, check that
the specified name is actually a field and not a method.
Fixes#29855.
Change-Id: Id77666e846f925907b1eec64213b1d25af8a2466
Reviewed-on: https://go-review.googlesource.com/c/158938
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Consider the following code:
func f(x []*T) interface{} {
return x
}
It returns an interface that holds a heap copy of x (by calling
convT2I or friend), therefore x escape to heap. The current
escape analysis only recognizes that x flows to the result. This
is not sufficient, since if the result does not escape, x's
content may be stack allocated and this will result a
heap-to-stack pointer, which is bad.
Fix this by realizing that if a CONVIFACE escapes and we're
converting from a non-direct interface type, the data needs to
escape to heap.
Running "toolstash -cmp" on std & cmd, the generated machine code
are identical for all packages. However, the export data (escape
tags) differ in the following packages. It looks to me that all
are similar to the "f" above, where the parameter should escape
to heap.
io/ioutil/ioutil.go:118
old: leaking param: r to result ~r1 level=0
new: leaking param: r
image/image.go:943
old: leaking param: p to result ~r0 level=1
new: leaking param content: p
net/url/url.go:200
old: leaking param: s to result ~r2 level=0
new: leaking param: s
(as a consequence)
net/url/url.go:183
old: leaking param: s to result ~r1 level=0
new: leaking param: s
net/url/url.go:194
old: leaking param: s to result ~r1 level=0
new: leaking param: s
net/url/url.go:699
old: leaking param: u to result ~r0 level=1
new: leaking param: u
net/url/url.go:775
old: (*URL).String u does not escape
new: leaking param content: u
net/url/url.go:1038
old: leaking param: u to result ~r0 level=1
new: leaking param: u
net/url/url.go:1099
old: (*URL).MarshalBinary u does not escape
new: leaking param content: u
flag/flag.go:235
old: leaking param: s to result ~r0 level=1
new: leaking param content: s
go/scanner/errors.go:105
old: leaking param: p to result ~r0 level=0
new: leaking param: p
database/sql/sql.go:204
old: leaking param: ns to result ~r0 level=0
new: leaking param: ns
go/constant/value.go:303
old: leaking param: re to result ~r2 level=0, leaking param: im to result ~r2 level=0
new: leaking param: re, leaking param: im
go/constant/value.go:846
old: leaking param: x to result ~r1 level=0
new: leaking param: x
encoding/xml/xml.go:518
old: leaking param: d to result ~r1 level=2
new: leaking param content: d
encoding/xml/xml.go:122
old: leaking param: leaking param: t to result ~r1 level=0
new: leaking param: t
crypto/x509/verify.go:506
old: leaking param: c to result ~r8 level=0
new: leaking param: c
crypto/x509/verify.go:563
old: leaking param: c to result ~r3 level=0, leaking param content: c
new: leaking param: c
crypto/x509/verify.go:615
old: (nothing)
new: leaking closure reference c
crypto/x509/verify.go:996
old: leaking param: c to result ~r1 level=0, leaking param content: c
new: leaking param: c
net/http/filetransport.go:30
old: leaking param: fs to result ~r1 level=0
new: leaking param: fs
net/http/h2_bundle.go:2684
old: leaking param: mh to result ~r0 level=2
new: leaking param content: mh
net/http/h2_bundle.go:7352
old: http2checkConnHeaders req does not escape
new: leaking param content: req
net/http/pprof/pprof.go:221
old: leaking param: name to result ~r1 level=0
new: leaking param: name
cmd/internal/bio/must.go:21
old: leaking param: w to result ~r1 level=0
new: leaking param: w
Fixes#29353.
Change-Id: I7e7798ae773728028b0dcae5bccb3ada51189c68
Reviewed-on: https://go-review.googlesource.com/c/162829
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: David Chase <drchase@google.com>
This change accepts the 'i' suffix on binary and octal integer
literals as well as hexadecimal floats. The suffix was already
accepted on decimal integers and floats.
Note that 0123i == 123i for backward-compatibility (and 09i is
valid).
See also the respective language in the spec change:
https://golang.org/cl/161098
Change-Id: I9d2d755cba36a3fa7b9e24308c73754d4568daaf
Reviewed-on: https://go-review.googlesource.com/c/162878
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
There are several places where a new (internal) complex constant is allocated
via new(Mpcplx) rather than newMpcmplx(). The problem with using new() is that
the Mpcplx data structure's Real and Imag components don't get initialized with
an Mpflt of the correct precision (they have precision 0, which may be adjusted
later).
In all cases but one, the components of those complex constants are set using
a Set operation which "inherits" the correct precision from the value that is
being set.
But when creating a complex value for an imaginary literal, the imaginary
component is set via SetString which assumes 64bits of precision by default.
As a result, the internal representation of 0.01i and complex(0, 0.01) was
not correct.
Replaced all used of new(Mpcplx) with newMpcmplx() and added a new test.
Fixes#30243.
Change-Id: Ife7fd6ccd42bf887a55c6ce91727754657e6cb2d
Reviewed-on: https://go-review.googlesource.com/c/163000
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
CL 154057 adds guards agaist out-of-bound reads from readonly
constants. It turns out that in dead code, the offset can also
be negative. Guard against negative offset as well.
Fixes#30257.
Change-Id: I47c2a2e434dd466c08ae6f50f213999a358c796e
Reviewed-on: https://go-review.googlesource.com/c/162819
Reviewed-by: Keith Randall <khr@golang.org>
Allow shifts by signed amounts. Panic if the shift amount is negative.
TODO: We end up doing two compares per shift, see Ian's comment
https://github.com/golang/go/issues/19113#issuecomment-443241799 that
we could do it with a single comparison in the normal case.
The prove pass mostly handles this code well. For instance, it removes the
<0 check for cases like this:
if s >= 0 { _ = x << s }
_ = x << len(a)
This case isn't handled well yet:
_ = x << (y & 0xf)
I'll do followon CLs for unhandled cases as needed.
Update #19113
R=go1.13
Change-Id: I839a5933d94b54ab04deb9dd5149f32c51c90fa1
Reviewed-on: https://go-review.googlesource.com/c/158719
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
This CL introduces compiler support for the new binary and octal integer
literals, hexadecimal floats, and digit separators for all number literals.
The new Go 2 number literal scanner accepts the following liberal format:
number = [ prefix ] digits [ "." digits ] [ exponent ] [ "i" ] .
prefix = "0" [ "b" |"B" | "o" | "O" | "x" | "X" ] .
digits = { digit | "_" } .
exponent = ( "e" | "E" | "p" | "P" ) [ "+" | "-" ] digits .
If the number starts with "0x" or "0X", digit is any hexadecimal digit;
otherwise, digit is any decimal digit. If the accepted number is not valid,
errors are reported accordingly.
See the new test cases in scanner_test.go for a selection of valid and
invalid numbers and the respective error messages.
R=Go1.13
Updates #12711.
Updates #19308.
Updates #28493.
Updates #29008.
Change-Id: Ic8febc7bd4dc5186b16a8c8897691e81125cf0ca
Reviewed-on: https://go-review.googlesource.com/c/157677
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Change-Id: Idee94a1d93555d53442098dd7479982e3f5afbba
Reviewed-on: https://go-review.googlesource.com/c/161339
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Make sure the argument to memmove is of pointer type before we try to
get the element type.
This has been noticed for code that uses unsafe+linkname so it can
call runtime.memmove. Probably not the best thing to allow, but the
code is out there and we'd rather not break it unnecessarily.
Fixes#30061
Change-Id: I334a8453f2e293959fd742044c43fbe93f0b3d31
Reviewed-on: https://go-review.googlesource.com/c/160826
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
We are copying the results to uninitialized stack space. Write
barrier is not needed.
Fixes#30041.
Change-Id: Ia91d74dbafd96dc2bd92de0cb479808991dda03e
Reviewed-on: https://go-review.googlesource.com/c/160737
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Treat compiler-generated init functions as wrappers, so they will not
be shown in tracebacks.
The exception to this rule is that we'd like to show the line number
of initializers for global variables in tracebacks. In order to
preserve line numbers for those cases, separate out the code for those
initializers into a separate function (which is not marked as
autogenerated).
This CL makes the go binary 0.2% bigger.
Fixes#29919
Change-Id: I0f1fbfc03d10d764ce3a8ddb48fb387ca8453386
Reviewed-on: https://go-review.googlesource.com/c/159717
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Whether a truncation should become a MOVWreg or a MOVWZreg doesn't
depend on the type of the operand, it depends on the type of the final
result. If the final result is unsigned, we can use MOVWZreg. If the
final result is signed, we can use MOVWreg. Checking the type of the
operand does the wrong thing if truncating an unsigned value to a
signed value, or vice-versa.
Fixes#29943
Change-Id: Ia6fc7d006486fa02cffd0bec4d910bdd5b6365f8
Reviewed-on: https://go-review.googlesource.com/c/159760
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
They can't be used, so we don't need code generated for them. We just
need to report errors in their bodies.
This is the minimal CL for 1.12. For 1.13, CL 158845 will remove
a bunch of special cases sprinkled about the compiler to handle "_"
functions, which should (after this CL) be unnecessary.
Update #29870
Change-Id: Iaa1c194bd0017dffdce86589fe2d36726ee83c13
Reviewed-on: https://go-review.googlesource.com/c/158820
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reuse the strict mechanism from FileLine for FuncForPC, so we don't
crash when asking the pcln table about bad pcs.
Fixes#29735
Change-Id: Iaffb32498b8586ecf4eae03823e8aecef841aa68
Reviewed-on: https://go-review.googlesource.com/c/157799
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Normally this happens when combining a sign extension and a load. We
want the resulting combo-instruction to get the line number of the
load, not the line number of the sign extension.
For each rule, compute where we should get its line number by finding
a value on the match side that can fault. Use that line number for
all the new values created on the right-hand side.
Fixes#27201
Change-Id: I19b3c6f468fff1a3c0bfbce2d6581828557064a3
Reviewed-on: https://go-review.googlesource.com/c/156937
Reviewed-by: David Chase <drchase@google.com>
Currently, obj.Ctxt's symbol table does not distinguish between ABI0
and ABIInternal symbols. This is *almost* okay, since a given symbol
name in the final object file is only going to belong to one ABI or
the other, but it requires that the compiler mark a Sym as being a
function symbol before it retrieves its LSym. If it retrieves the LSym
first, that LSym will be created as ABI0, and later marking the Sym as
a function symbol won't change the LSym's ABI.
Marking a Sym as a function symbol before looking up its LSym sounds
easy, except Syms have a dual purpose: they are used just as interned
strings (every function, variable, parameter, etc with the same
textual name shares a Sym), and *also* to store state for whatever
package global has that name. As a result, it's easy to slip up and
look up an LSym when a Sym is serving as the name of a local variable,
and then later mark it as a function when it's serving as the global
with the name.
In general, we were careful to avoid this, but #29610 demonstrates one
case where we messed up. Because of on-demand importing from indexed
export data, it's possible to compile a method wrapper for a type
imported from another package before importing an init function from
that package. If the argument of the method is named "init", the
"init" LSym will be created as a data symbol when compiling the
wrapper, before it gets marked as a function symbol.
To fix this, we separate obj.Ctxt's symbol tables for ABI0 and
ABIInternal symbols. This way, the compiler will simply get a
different LSym once the Sym takes on its package-global meaning as a
function.
This fixes the above ordering issue, and means we no longer need to go
out of our way to create the "init" function early and mark it as a
function symbol.
Fixes#29610.
Updates #27539.
Change-Id: Id9458b40017893d46ef9e4a3f9b47fc49e1ce8df
Reviewed-on: https://go-review.googlesource.com/c/157017
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Returning the innermost frame instead of the outermost
makes code that walks the results of runtime.Caller{,s}
still work correctly in the presence of mid-stack inlining.
Fixes#29582
Change-Id: I2392e3dd5636eb8c6f58620a61cef2194fe660a7
Reviewed-on: https://go-review.googlesource.com/c/156364
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The compiler appears to contain several squirrelly corner
cases where nodes are double walked, some where new nodes
are created from walked parts. Rather than trust that we
had searched hard enough for the last one, change
exprSwitch.walk() to return immediately if it has already
been walked. This appears to be the only case where
double-walking a node is actually harmful.
Fixes#29562.
Change-Id: I0667e8769aba4c3236666cd836a934e256c0bfc5
Reviewed-on: https://go-review.googlesource.com/c/156317
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
As a followon to CL 152537, modify the panic-printing traceback
to also handle mid-stack inlining correctly.
Also declare -fm functions (aka method functions) as wrappers, so that
they get elided during traceback. This fixes part 2 of #26839.
Fixes#28640Fixes#24488
Update #26839
Change-Id: I1c535a9b87a9a1ea699621be1e6526877b696c21
Reviewed-on: https://go-review.googlesource.com/c/153477
Reviewed-by: David Chase <drchase@google.com>
Use the length of the bitmap to decide how much to pass to the
write barrier, not the total length of the arguments.
The test needs enough arguments so that two distinct bitmaps
get interpreted as a single longer bitmap.
Update #29362
Change-Id: I78f3f7f9ec89c2ad4678f0c52d3d3def9cac8e72
Reviewed-on: https://go-review.googlesource.com/c/156123
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
In the case of x+d >= w, where d and w are constants, we are
deriving x is within the bound of min=w-d and max=maxInt-d. When
there is an overflow (min >= max), we know only one of x >= min
or x <= max is true, and we derive this by excluding the other.
When excluding x >= min, we did not consider the equal case, so
we could incorrectly derive x <= max when x == min.
Fixes#29502.
Change-Id: Ia9f7d814264b1a3ddf78f52e2ce23377450e6e8a
Reviewed-on: https://go-review.googlesource.com/c/156019
Reviewed-by: David Chase <drchase@google.com>
CL 155917 added a -race test that shouldn't be run when cgo is not
enabled. Enforce this in the test file, with a buildflag.
Fixes the nocgo builder.
Change-Id: I9fe0d8f21da4d6e2de3f8fe9395e1fa7e9664b02
Reviewed-on: https://go-review.googlesource.com/c/155957
Run-TryBot: Alberto Donizetti <alb.donizetti@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reorg map flags a bit so we don't need any extra space for the extra flag.
Fixes#23734
Change-Id: I436812156240ae90de53d0943fe1aabf3ea37417
Reviewed-on: https://go-review.googlesource.com/c/155918
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
We can't remove race instrumentation unless there are no calls,
not just no static calls. Closure and interface calls also count.
The problem in issue 29329 is that there was a racefuncenter, an
InterCall, and a racefuncexit. The racefuncenter was removed, then
the InterCall was rewritten to a StaticCall. That prevented the
racefuncexit from being removed. That caused an imbalance in
racefuncenter/racefuncexit calls, which made the race detector barf.
Bug introduced at CL 121235
Fixes#29329
Change-Id: I2c94ac6cf918dd910b74b2a0de5dc2480d236f16
Reviewed-on: https://go-review.googlesource.com/c/155917
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Work involved in getting a stack trace is divided between
runtime.Callers and runtime.CallersFrames.
Before this CL, runtime.Callers returns a pc per runtime frame.
runtime.CallersFrames is responsible for expanding a runtime frame
into potentially multiple user frames.
After this CL, runtime.Callers returns a pc per user frame.
runtime.CallersFrames just maps those to user frame info.
Entries in the result of runtime.Callers are now pcs
of the calls (or of the inline marks), not of the instruction
just after the call.
Fixes#29007Fixes#28640
Update #26320
Change-Id: I1c9567596ff73dc73271311005097a9188c3406f
Reviewed-on: https://go-review.googlesource.com/c/152537
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
(SGTconst [c] (SRLconst _ [d])) && 0 <= int32(c) && uint32(d) <= 31 && 1<<(32-uint32(d)) <= int32(c) -> (MOVWconst [1])
This rule is problematic. 1<<(32-uint32(d)) <= int32(c) meant to
say that it is true if c is greater than the largest possible
value of the right shift. But when d==1, 1<<(32-1) is negative
and results in the wrong comparison.
Rewrite the rules in a more direct way.
Fixes#29402.
Change-Id: I5940fc9538d9bc3a4bcae8aa34672867540dc60e
Reviewed-on: https://go-review.googlesource.com/c/155798
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
If someone takes a pointer to a zero-sized stack variable, it can
be incorrectly interpreted as a pointer to the next object in the
stack frame. To avoid this, add some padding after zero-sized variables.
We only need to pad if the next variable in memory (which is the
previous variable in the order in which we allocate variables to the
stack frame) has pointers. If the next variable has no pointers, it
won't hurt to have a pointer to it.
Because we allocate all pointer-containing variables before all
non-pointer-containing variables, we should only have to pad once per
frame.
Fixes#24993
Change-Id: Ife561cdfdf964fdbf69af03ae6ba97d004e6193c
Reviewed-on: https://go-review.googlesource.com/c/155698
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Method expressions where the method is implicitly declared have no
line number. The Error method of the built-in error type is one such
method. We leave the line number at the use of the method expression
in this case.
Fixes#29389
Change-Id: I29c64bb47b1a704576abf086599eb5af7b78df53
Reviewed-on: https://go-review.googlesource.com/c/155639
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
It was possible that
var X interface{} = 'x'
could cause a compilation failure due to having not calculated rune's
width yet. typecheck.go normally calculates the width of things, but
it doesn't for implicit conversions to default type. We already
compute the width of all of the standard numeric types in universe.go,
but we failed to calculate it for the rune alias type. So we could
later crash if the code never otherwise explicitly mentioned 'rune'.
While here, explicitly compute widths for 'byte' and 'error' for
consistency.
Fixes#29350.
Change-Id: Ifedd4899527c983ee5258dcf75aaf635b6f812f8
Reviewed-on: https://go-review.googlesource.com/c/155380
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
Out-of-bounds reads of globals can happen in dead code. For code
like this:
s := "a"
if len(s) == 3 {
load s[0], s[1], and s[2]
}
The out-of-bounds loads are dead code, but aren't removed yet
when lowering. We need to not panic when compile-time evaluating
those loads. This can only happen for dead code, so the result
doesn't matter.
Fixes#29215
Change-Id: I7fb765766328b9524c6f2a1e6ab8d8edd9875097
Reviewed-on: https://go-review.googlesource.com/c/154057
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alberto Donizetti <alb.donizetti@gmail.com>
The formatting routines for types use a depth limit as primitive
mechanism to detect cycles. For now, increase the limit from 100
to 250 and file #29312 so we don't drop this on the floor.
Also, adjust some fatal error messages elsewhere to use
better formatting.
Fixes#29264.
Updates #29312.
Change-Id: Idd529f6682d478e0dcd2d469cb802192190602f6
Reviewed-on: https://go-review.googlesource.com/c/154583
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
When a println arg contains a call to an inlineable function
that itself contains a switch, that switch statement will be
walked twice, once by the walkexprlist formerly in the
OPRINT/OPRINTN case, then by walkexprlistcheap in walkprint.
Remove the first walkexprlist, it is not necessary.
walkexprlist =
s[i] = walkexpr(s[i], init)
walkexprlistcheap = {
s[i] = cheapexpr(n, init)
s[i] = walkexpr(s[i], init)
}
Seems like this might be possible in other places, i.e.,
calls to inlineable switch-containing functions.
See also #25776.
Fixes#29220.
Change-Id: I3781e86aad6688711597b8bee9bc7ebd3af93601
Reviewed-on: https://go-review.googlesource.com/c/154497
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
A prior optimization (https://golang.org/cl/106175) removed the
generation of unnecessary method expression wrappers, but also
eliminated the generation of the wrapper for error.Error which
was still required.
Special-case error type in the optimization.
Fixes#29304.
Change-Id: I54c8afc88a2c6d1906afa2d09c68a0a3f3e2f1e3
Reviewed-on: https://go-review.googlesource.com/c/154578
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Instead of testing len(slice)+numNewElements > cap(slice) use
uint(len(slice)+numNewElements) > uint(cap(slice)) to test
if a slice needs to be grown in an append operation.
This prevents a possible overflow when len(slice) is near the maximum
int value and the addition of a constant number of new elements
makes it overflow and wrap around to a negative number which is
smaller than the capacity of the slice.
Appending a slice to a slice with append(s1, s2...) already used
a uint comparison to test slice capacity and therefore was not
vulnerable to the same overflow issue.
Fixes: #29190
Change-Id: I41733895838b4f80a44f827bf900ce931d8be5ca
Reviewed-on: https://go-review.googlesource.com/c/154037
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
By combining the load+op, we may force the op to happen earlier in
the store chain. That might force the SymAddr operation earlier, and
in particular earlier than its corresponding VarDef. That leads to
an invalid schedule, so avoid that.
This is kind of a hack to work around the issue presented. I think
the underlying problem, that LEAQ is not directly ordered with respect
to its vardef, is the real problem. The benefit of this CL is that
it fixes the immediate issue, is small, and obviously won't break
anything. A real fix for this issue is much more invasive.
The go binary is unchanged in size.
This situation just doesn't occur very often.
Fixes#28445
Change-Id: I13a765e13f075d5b6808a355ef3c43cdd7cd47b6
Reviewed-on: https://go-review.googlesource.com/c/153641
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
When functions are inlined, for instructions in the inlined body, does
-S print the location of the call, or the location of the body? Right
now, we do the former. I'd like to do the latter by default, it makes
much more sense when reading disassembly. With mid-stack inlining
enabled in more cases, this quandry will come up more often.
The original behavior is still available with -S=2. Some tests
use this mode (so they can find assembly generated by a particular
source line).
This helped me with understanding what the compiler was doing
while fixing #29007.
Change-Id: Id14a3a41e1b18901e7c5e460aa4caf6d940ed064
Reviewed-on: https://go-review.googlesource.com/c/153241
Reviewed-by: David Chase <drchase@google.com>
IsSliceInBounds(x, y) asserts that y is not negative, but
there were cases where this is not true. Change code
generation to ensure that this is true when it's not obviously
true. Prove phase cleans a few of these out.
With this change the compiler text section is 0.06% larger,
that is, not very much. Benchmarking still TBD, may need
to wait for access to a benchmarking box (next week).
Also corrected run.go to handle '?' in -update_errors output.
Fixes#28797.
Change-Id: Ia8af90bc50a91ae6e934ef973def8d3f398fac7b
Reviewed-on: https://go-review.googlesource.com/c/152477
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Currently,
for i := range a {
a[i] = nil
}
will compile to have write barriers even if a is a slice of pointers
to go:notinheap types. This happens because the optimization that
transforms this into a memclr only asks it a's element type has
pointers, and not if it specifically has heap pointers.
Fix this by changing arrayClear to use HasHeapPointer instead of
types.Haspointers. We probably shouldn't have both of these functions,
since a pointer to a notinheap type is effectively a uintptr, but
that's not going to change in this CL.
Change-Id: I284b85bdec6ae1e641f894e8f577989facdb0cf1
Reviewed-on: https://go-review.googlesource.com/c/152723
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Previously, when a function signature had defined a non-final variadic
parameter, the error message always referred to the type associated with that
parameter. However, if the offending parameter's name was part of an identifier
list with a variadic type, one could misinterpret the message, thinking the
problem had been with one of the other names in the identifer list.
func bar(a, b ...int) {}
clear ~~~~~~~^ ^~~~~~~~ confusing
This change updates the error message and sets the column position to that of
the offending parameter's name, if it exists.
Fixes#28450.
Change-Id: I076f560925598ed90e218c25d70f9449ffd9b3ea
Reviewed-on: https://go-review.googlesource.com/c/152417
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
For recursive functions, the parameters were iterated using
fn.Name.Defn.Func.Dcl, which does not include unnamed/blank
parameters. This results in a mismatch in formal-actual
assignments, for example,
func f(_ T, x T)
f(a, b) should result in { _=a, x=b }, but the escape analysis
currently sees only { x=a } and drops b on the floor. This may
cause b to not escape when it should (or a escape when it should
not).
Fix this by using fntype.Params().FieldSlice() instead, which
does include unnamed parameters.
Also add a sanity check that ensures all the actual parameters
are consumed.
Fixes#29000
Change-Id: Icd86f2b5d71e7ebbab76e375b7702f62efcf59ae
Reviewed-on: https://go-review.googlesource.com/c/152617
Reviewed-by: Keith Randall <khr@golang.org>
staticcopy of a struct or array should recursively call itself, not
staticassign.
This fixes an issue where a struct with a slice in it is copied during
static initialization. In this case, the backing array for the slice
is duplicated, and each copy of the slice refers to a different
backing array, which is incorrect. That issue has existed since at
least Go 1.2.
I'm not sure why this was never noticed. It seems like a pretty
obvious bug if anyone modifies the resulting slice.
In any case, we started to notice when the optimization in CL 140301
landed. Here is basically what happens in issue29013b.go:
1) The error above happens, so we get two backing stores for what
should be the same slice.
2) The code for initializing those backing stores is reused.
But not duplicated: they are the same Node structure.
3) The order pass allocates temporaries for the map operations.
For the first instance, things work fine and two temporaries are
allocated and stored in the OKEY nodes. For the second instance,
the order pass decides new temporaries aren't needed, because
the OKEY nodes already have temporaries in them.
But the order pass also puts a VARKILL of the temporaries between
the two instance initializations.
4) In this state, the code is technically incorrect. But before
CL 140301 it happens to work because the temporaries are still
correctly initialized when they are used for the second time. But then...
5) The new CL 140301 sees the VARKILLs and decides to reuse the
temporary for instance 1 map 2 to initialize the instance 2 map 1
map. Because the keys aren't re-initialized, instance 2 map 1
gets the wrong key inserted into it.
Fixes#29013
Change-Id: I840ce1b297d119caa706acd90e1517a5e47e9848
Reviewed-on: https://go-review.googlesource.com/c/152081
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
A Go user made a well-documented request for a slightly
lower threshold. I tested against a selection of other
people's benchmarks, and saw a tiny benefit (possibly noise)
at equally tiny cost, and no unpleasant surprises observed
in benchmarking.
I.e., might help, doesn't hurt, low risk, request was
delivered on a silver platter.
It did, however, change the behavior of one test because
now bytes.Buffer.Grow is eligible for inlining.
Updates #19348.
Change-Id: I85e3088a4911290872b8c6bda9601b5354c48695
Reviewed-on: https://go-review.googlesource.com/c/151977
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This CL adds several test cases of arithmetic operations for
386/amd64/arm/arm64.
Change-Id: I362687c06249f31091458a1d8c45fc4d006b616a
Reviewed-on: https://go-review.googlesource.com/c/151897
Run-TryBot: Ben Shi <powerman1st@163.com>
Reviewed-by: Keith Randall <khr@golang.org>
While here, rename nonnegintconst to indexconst (because that's
what it is) and add Fatalf calls where we are not expecting the
indexconst call to fail, and fixed wrong comparison in smallintconst.
Fixes#23781.
Change-Id: I86eb13081c450943b1806dfe3ae368872f76639a
Reviewed-on: https://go-review.googlesource.com/c/151599
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
We don't need a write barrier if:
1) The location we're writing to doesn't hold a heap pointer, and
2) The value we're writing isn't a heap pointer.
The freshly returned value from runtime.newobject satisfies (1).
Pointers to globals, and the contents of the read-only data section satisfy (2).
This is particularly helpful for code like:
p := []string{"abc", "def", "ghi"}
Where the compiler generates:
a := new([3]string)
move(a, statictmp_) // eliminates write barriers here
p := a[:]
For big slice literals, this makes the code a smaller and faster to
compile.
Update #13554. Reduces the compile time by ~10% and RSS by ~30%.
Change-Id: Icab81db7591c8777f68e5d528abd48c7e44c87eb
Reviewed-on: https://go-review.googlesource.com/c/151498
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
A little bit of compiler stress testing. Randomize the order
of the values in a block before every phase. This randomization
makes sure that we're not implicitly depending on that order.
Currently the random seed is a hash of the function name.
It provides determinism, but sacrifices some coverage.
Other arrangements are possible (env var, ...) but require
more setup.
Fixes#20178
Change-Id: Idae792a23264bd9a3507db6ba49b6d591a608e83
Reviewed-on: https://go-review.googlesource.com/c/33909
Reviewed-by: Cherry Zhang <cherryyz@google.com>
We want to issue loads as soon as possible, especially when they
are going to miss in the cache. Using a conditional move (CMOV) here:
i := ...
if cond {
i++
}
... = a[i]
means that we have to wait for cond to be computed before the load
is issued. Without a CMOV, if the branch is predicted correctly the
load can be issued in parallel with computing cond.
Even if the branch is predicted incorrectly, maybe the speculative
load is close to the real load, and we get a prefetch for free.
In the worst case, when the prediction is wrong and the address is
way off, we only lose by the time difference between the CMOV
latency (~2 cycles) and the mispredict restart latency (~15 cycles).
We only squash CMOVs that affect load addresses. Results of CMOVs
that are used for other things (store addresses, store values) we
use as before.
Fixes#26306
Change-Id: I82ca14b664bf05e1d45e58de8c4d9c775a127ca1
Reviewed-on: https://go-review.googlesource.com/c/145717
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
This commit fixes a mistake made in CL 144538.
This nilcheck can be removed because OpPPC64LoweredMove will fault if
arg0 is nil, as it's used to store. Further information can be found in
cmd/compile/internal/ssa/nilcheck.go.
Change-Id: Ifec0080c00eb1f94a8c02f8bf60b93308e71b119
Reviewed-on: https://go-review.googlesource.com/c/151298
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Note that the intrinsic implementation panics separately for overflow and
divide by zero, which matches the behavior of the pure go implementation.
There is a modest performance improvement after intrinsic implementation.
name old time/op new time/op delta
Div-4 53.0ns ± 1% 47.0ns ± 0% -11.28% (p=0.008 n=5+5)
Div32-4 18.4ns ± 0% 18.5ns ± 1% ~ (p=0.444 n=5+5)
Div64-4 53.3ns ± 0% 47.5ns ± 4% -10.77% (p=0.008 n=5+5)
Updates #28273
Change-Id: Ic1688ecc0964acace2e91bf44ef16f5fb6b6bc82
Reviewed-on: https://go-review.googlesource.com/c/144378
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Don't convert values that aren't Go constants, like
uintptr(unsafe.Pointer(nil)), to a literal constant. This avoids
assuming they are constants for things like indexing, array sizes,
case duplication, etc.
Also, nil is an allowed duplicate in switches. CTNILs aren't Go constants.
Fixes#28078Fixes#28079
Change-Id: I9ab8af47098651ea09ef10481787eae2ae2fb445
Reviewed-on: https://go-review.googlesource.com/c/151320
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
When a slice composite literal is sparse, initialize it dynamically
instead of statically.
s := []int{5:5, 20:20}
To initialize the backing store for s, use 2 constant writes instead
of copying from a static array with 21 entries.
This CL also fixes pathologies in the compiler when the slice is
*very* sparse.
Fixes#23780
Change-Id: Iae95c6e6f6a0e2994675cbc750d7a4dd6436b13b
Reviewed-on: https://go-review.googlesource.com/c/151319
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Abort evconst if its argument isn't a Go constant. The SSA backend
will do the optimizations in question later. They tend to be weird
cases, like uintptr(unsafe.Pointer(uintptr(1))).
Fix OADDSTR and OCOMPLEX cases in isGoConst.
OADDSTR has its arguments in n.List, not n.Left and n.Right.
OCOMPLEX might have a 2-result function as its arg in List[0]
(in which case it isn't a Go constant).
Fixes#24760
Change-Id: Iab312d994240d99b3f69bfb33a443607e872b01d
Reviewed-on: https://go-review.googlesource.com/c/151338
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
In assembly free packages (aka "complete" or "pure go"), allow
bodyless functions if they are linkname'd to something else.
Presumably the thing the function is linkname'd to has a definition.
If not, the linker will complain. And linkname is unsafe, so we expect
users to know what they are doing.
Note this handles only one direction, where the linkname directive
is in the local package. If the linkname directive is in the remote
package, this CL won't help. (See os/signal/sig.s for an example.)
Fixes#23311
Change-Id: I824361b4b582ee05976d94812e5b0e8b0f7a18a6
Reviewed-on: https://go-review.googlesource.com/c/151318
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This commit adapts compile tool to create correct nilchecks for AIX.
AIX allows to load a nil pointer. Therefore, the default nilcheck
which issues a load must be replaced by a CMP instruction followed by a
store at 0x0 if the value is nil. The store will trigger a SIGSEGV as on
others OS.
The nilcheck algorithm must be adapted to do not remove nilcheck if it's
only a read. Stores are detected with v.Type.IsMemory().
Tests related to nilptr must be adapted to the previous changements.
nilptr.go cannot be used as it's because the AIX address space starts at
1<<32.
Change-Id: I9f5aaf0b7e185d736a9b119c0ed2fe4e5bd1e7af
Reviewed-on: https://go-review.googlesource.com/c/144538
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit allows the runtime to handle 64bits addresses returned by
mmap syscall on AIX.
Mmap syscall returns addresses on 59bits on AIX. But the Arena
implementation only allows addresses with less than 48 bits.
This commit increases the arena size up to 1<<60 for aix/ppc64.
Update: #25893
Change-Id: Iea72e8a944d10d4f00be915785e33ae82dd6329e
Reviewed-on: https://go-review.googlesource.com/c/138736
Reviewed-by: Austin Clements <austin@google.com>
Currently, both asm and compile have a -symabis flag, but in asm it's
a boolean flag that means to generate a symbol ABIs file and in the
compiler its a string flag giving the path of the symbol ABIs file to
consume. I'm worried about this false symmetry biting us in the
future, so rename asm's flag to -gensymabis.
Updates #27539.
Change-Id: I8b9c18a852d2838099718f8989813f19d82e7434
Reviewed-on: https://go-review.googlesource.com/c/149818
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The current support_XXX variables are specific for the
amd64 and 386 platforms.
Prefix processor capability variables by architecture to have a
consistent naming scheme and avoid reuse of the existing
variables for new platforms.
This also aligns naming of runtime variables closer with internal/cpu
processor capability variable names.
Change-Id: I3eabb29a03874678851376185d3a62e73c1aff1d
Reviewed-on: https://go-review.googlesource.com/c/91435
Run-TryBot: Martin Möhrmann <martisch@uos.de>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
When using soft-float, OMUL might be rewritten to function call
so we should ensure it was evaluated first.
Fixes#28688
Change-Id: I30b87501782fff62d35151f394a1c22b0d490c6c
Reviewed-on: https://go-review.googlesource.com/c/148837
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Move the empty header file created by "builddir", "buildrundir"
directives to t.tempDir. The file was accidentally placed in the
same directory as the source code and this was a vestige of CL 146999.
Fixes#28781
Change-Id: I3d2ada5f9e8bf4ce4f015b9bd379b311592fe3ce
Reviewed-on: https://go-review.googlesource.com/c/149458
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Because run.go doesn't pass the package being compiled to the compiler
via the -p flag, it can't match up the main·f symbol from the
assembler with the "func f" stub in Go, so it doesn't produce the
correct assembly stub.
Fix this by removing the package prefix from the assembly definition.
Alternatively, we could make run.go pass -p to the compiler, but it's
nicer to remove these package prefixes anyway.
Should fix the linux-arm builder, which was broken by the introduction
of function ABIs in CL 147160.
Updates #27539.
Change-Id: Id62b7701e1108a21a5ad48ffdb5dad4356c273a6
Reviewed-on: https://go-review.googlesource.com/c/149483
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
When we set an explicit argmap, we may want only a prefix of that
argmap. Argmap is set when the function is reflect.makeFuncStub or
reflect.methodValueCall. In this case, arglen specifies how much of
the args section is actually live. (It could be either all the args +
results, or just the args.)
Fixes#28750
Change-Id: Idf060607f15a298ac591016994e58e22f7f92d83
Reviewed-on: https://go-review.googlesource.com/c/149217
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This is a little clearer, and we're about to need the .s file list in
one more place, so this will cut down on duplication.
Change-Id: I4da8bf03a0469fb97565b0841c40d505657b574e
Reviewed-on: https://go-review.googlesource.com/c/146998
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
We have an existing optimization that recognizes
memory moves of the form A -> B -> C and converts
them into A -> C, in the hopes that the store to
B will be end up being dead and thus eliminated.
However, when A, B, and C are large types,
the front end sometimes emits VarDef ops for the moves.
This change adds an optimization to match that pattern.
This required changing an old compiler test.
The test assumed that a temporary was required
to deal with a large return value.
With this optimization in place, that temporary
ended up being eliminated.
Triggers 649 times during 'go build -a std cmd'.
Cuts 16k off cmd/go.
name old object-bytes new object-bytes delta
Template 507kB ± 0% 507kB ± 0% -0.15% (p=0.008 n=5+5)
Unicode 225kB ± 0% 225kB ± 0% ~ (all equal)
GoTypes 1.85MB ± 0% 1.85MB ± 0% ~ (all equal)
Flate 328kB ± 0% 328kB ± 0% ~ (all equal)
GoParser 402kB ± 0% 402kB ± 0% -0.00% (p=0.008 n=5+5)
Reflect 1.41MB ± 0% 1.41MB ± 0% -0.20% (p=0.008 n=5+5)
Tar 458kB ± 0% 458kB ± 0% ~ (all equal)
XML 601kB ± 0% 599kB ± 0% -0.21% (p=0.008 n=5+5)
Change-Id: I9b5f25c8663a0b772ad1ee51fa61f74b74d26dd3
Reviewed-on: https://go-review.googlesource.com/c/143479
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Munday <mike.munday@ibm.com>
This change makes use of the cc versions of the AND, OR, XOR
instructions, omitting the need for a CMP instruction.
In many test programs and in the go binary, this reduces the
size of 20-30 functions by at least 1 instruction, many in
runtime.
Testcase added to test/codegen/comparisons.go
Change-Id: I6cc1ca8b80b065d7390749c625bc9784b0039adb
Reviewed-on: https://go-review.googlesource.com/c/143059
Reviewed-by: Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>
Reviewed-by: Michael Munday <mike.munday@ibm.com>
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This is a simple tweak to allow a bit more mid-stack inlining.
In cases like this:
func f() {
g()
}
We'd really like to inline f into its callers. It can't hurt.
We implement this optimization by making calls a bit cheaper, enough
to afford a single call in the function body, but not 2.
The remaining budget allows for some argument modification, or perhaps
a wrapping conditional:
func f(x int) {
g(x, 0)
}
func f(x int) {
if x > 0 {
g()
}
}
Update #19348
Change-Id: Ifb1ea0dd1db216c3fd5c453c31c3355561fe406f
Reviewed-on: https://go-review.googlesource.com/c/147361
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: David Chase <drchase@google.com>
Dead-code eliminating labels is tricky because there might
be gotos that can still reach them.
Bug probably introduced with CL 91056
Fixes#28616
Change-Id: I6680465134e3486dcb658896f5172606cc51b104
Reviewed-on: https://go-review.googlesource.com/c/147817
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Iskander Sharipov <iskander.sharipov@intel.com>
This change re-introduces (temporarily) a work-around for recursive
alias type declarations, originally in https://golang.org/cl/35831/
(intended as fix for #18640). The work-around was removed later
for a more comprehensive cycle detection check. That check
contained a subtle error which made the code appear to work,
while in fact creating incorrect types internally. See #25838
for details.
By re-introducing the original work-around, we eliminate problems
with many simple recursive type declarations involving aliases;
specifically cases such as #27232 and #27267. However, the more
general problem remains.
This CL also fixes the subtle error (incorrect variable use when
analyzing a type cycle) mentioned above and now issues a fatal
error with a reference to the relevant issue (rather than crashing
later during the compilation). While not great, this is better
than the current status. The long-term solution will need to
address these cycles (see #25838).
As a consequence, several old test cases are not accepted anymore
by the compiler since they happened to work accidentally only.
This CL disables parts or all code of those test cases. The issues
are: #18640, #23823, and #24939.
One of the new test cases (fixedbugs/issue27232.go) exposed a
go/types issue. The test case is excluded from the go/types test
suite and an issue was filed (#28576).
Updates #18640.
Updates #23823.
Updates #24939.
Updates #25838.
Updates #28576.
Fixes#27232.
Fixes#27267.
Change-Id: I6c2d10da98bfc6f4f445c755fcaab17fc7b214c5
Reviewed-on: https://go-review.googlesource.com/c/147286
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Unlikely to happen in practice, but easy enough to prevent and might
as well do so for completeness.
Fixes#28243.
Change-Id: I848c3af49cb923f088e9490c6a79373e182fad08
Reviewed-on: https://go-review.googlesource.com/c/142719
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Austin Clements <austin@google.com>
This commit skips tests which aren't yet supported on AIX.
nosplit.go is disabled because stackGuardMultiplier is increased for
syscalls.
Change-Id: Ib5ff9a4539c7646bcb6caee159f105ff8a160ad7
Reviewed-on: https://go-review.googlesource.com/c/146939
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
For moves >8,<16 bytes, do a move using non-overlapping loads/stores
if it would require no more instructions.
This helps a bit with the case when the move is from a static
constant, because then the code to materialize the value being moved
is smaller.
Change-Id: Ie47a5a7c654afeb4973142b0a9922faea13c9b54
Reviewed-on: https://go-review.googlesource.com/c/146019
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This CL fixes several typos and adds two more cases
to arithmetic test.
Change-Id: I086560162ea351e2166866e444e2317da36c1729
Reviewed-on: https://go-review.googlesource.com/c/145210
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This reverts commit 9ce87a63b9.
The fix addresses the specific test case, but not the general
problem.
Updates #24755.
Change-Id: I0ba8463b41b099b1ebf49759f88a423b40f70d58
Reviewed-on: https://go-review.googlesource.com/c/145617
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This way, once the constant declarations are typechecked, all named
types are fully typechecked and have all of their methods added.
Usually this isn't important, as methods and interfaces cannot be used
in constant declarations. However, it can lead to confusing and
incorrect errors, such as:
$ cat f.go
package p
type I interface{ F() }
type T struct{}
const _ = I(T{})
func (T) F() {}
$ go build f.go
./f.go:6:12: cannot convert T literal (type T) to type I:
T does not implement I (missing F method)
The error is clearly wrong, as T does have an F method. If we ensure
that all funcs are typechecked before all constant declarations, we get
the correct error:
$ go build f2.go
# command-line-arguments
./f.go:6:7: const initializer I(T literal) is not a constant
Fixes#24755.
Change-Id: I182b60397b9cac521d9a9ffadb11b42fd42e42fe
Reviewed-on: https://go-review.googlesource.com/c/115096
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
CL 114797 reworked how arguments get written to the stack.
Some type conversions got lost in the process. Restore them.
Fixes#28390
Updates #28430
Change-Id: Ia0d37428d7d615c865500bbd1a7a4167554ee34f
Reviewed-on: https://go-review.googlesource.com/c/144598
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Unlike normal load+op opcodes, the load+compare opcode does
not clobber its non-load argument. Allow the load+compare merge
to happen even if the non-load argument is used elsewhere.
Noticed when investigating issue #28417.
Change-Id: Ibc48d1f2e06ae76034c59f453815d263e8ec7288
Reviewed-on: https://go-review.googlesource.com/c/145097
Reviewed-by: Ainar Garipov <gugl.zadolbal@gmail.com>
Reviewed-by: Ben Shi <powerman1st@163.com>
If a field and method have the same name, mark the respective struct field
so that we don't report follow-on errors when the field/method is accessed.
Per suggestion of @mdempsky.
Fixes#28268.
Change-Id: Ia1ca4cdfe9bacd3739d1fd7ca5e014ca094245ee
Reviewed-on: https://go-review.googlesource.com/c/144259
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
prove is able to find 94 occurrences in std cmd where a divisor
can't have the value -1. The change removes
the extraneous fix-up code for these cases.
Fixes#25239
Change-Id: Ic184de971f47cc57c702eb72805b8e291c14035d
Reviewed-on: https://go-review.googlesource.com/c/130215
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
The second and subsequent return values from f() need to be
converted to the element type of the first return value from f()
(which must be a slice).
Fixes#22327
Change-Id: I5c0a424812c82c1b95b6d124c5626cfc4408bdb6
Reviewed-on: https://go-review.googlesource.com/c/142718
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This CL add 3 rules to combine byte-store to word-store on386 and
amd64.
Change-Id: Iffd9cda42f1961680c81def4edc773ad58f211b3
Reviewed-on: https://go-review.googlesource.com/c/143057
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
As of https://golang.org/cl/43456 gccgo now gives a better error
message for this test.
Before:
fixedbugs/issue5089.go:13:1: error: redefinition of ‘bufio.Buffered’: receiver name changed
func (b *bufio.Reader) Buffered() int { // ERROR "non-local|redefinition"
^
fixedbugs/issue5089.go:11:13: note: previous definition of ‘bufio.Buffered’ was here
import "bufio" // GCCGO_ERROR "previous"
^
Now:
fixedbugs/issue5089.go:13:7: error: may not define methods on non-local type
func (b *bufio.Reader) Buffered() int { // ERROR "non-local|redefinition"
^
Change-Id: I4112ca8d91336f6369f780c1d45b8915b5e8e235
Reviewed-on: https://go-review.googlesource.com/c/130955
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Building with gccgo failed with an undefined symbol error from an
unnecessary hash function.
Updates #19773
Change-Id: Ic78bf1b086ff5ee26d464089c0e14987d3fe8b02
Reviewed-on: https://go-review.googlesource.com/c/130956
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This CL adds more combined load/store test cases for 386/amd64.
Change-Id: I0a483a6ed0212b65c5e84d67ed8c9f50c389ce2d
Reviewed-on: https://go-review.googlesource.com/c/142878
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Nowadays there are better ways to safely run untrusted Go programs, like
NaCl and gVisor.
Change-Id: I20c45f13a50dbcf35c343438b720eb93e7b4e13a
Reviewed-on: https://go-review.googlesource.com/c/142717
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
This appears to have simply been an oversight.
Change-Id: Ia5d1309b3ebc99c9abbf0282397693272d8178aa
Reviewed-on: https://go-review.googlesource.com/c/142885
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Ensure that label redefinition error column numbers
print the actual start of the label instead of the
position of the label's delimiting token ":".
For example, given this program:
package main
func main() {
foo:
foo:
foo:
foo :
}
* Before:
main.go:5:13: label foo defined and not used
main.go:6:7: label foo already defined at main.go:5:13
main.go:7:4: label foo already defined at main.go:5:13
main.go:8:16: label foo already defined at main.go:5:13
* After:
main.go:5:13: label foo defined and not used
main.go:6:4: label foo already defined at main.go:5:13
main.go:7:1: label foo already defined at main.go:5:13
main.go:8:1: label foo already defined at main.go:5:13
Fixes#26411
Change-Id: I8eb874b97fdc8862547176d57ac2fa0f075f2367
Reviewed-on: https://go-review.googlesource.com/c/124595
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Numbers without decimals are valid Go representations of whole-number
floats. That is, "var x float64 = 5" is valid Go. Avoid breakage in
tests that expect a certain output from %#v by reverting to it.
To guarantee the right type is generated by a print use %T(%#v) instead.
Added a test to lock in this behavior.
This reverts commit 7c7cecc184.
Fixes#27634
Updates #26363
Change-Id: I544c400a0903777dd216452a7e86dfe60b0b0283
Reviewed-on: https://go-review.googlesource.com/c/142597
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
ARMv7's MULAF/MULSF/MULAD/MULSD are not fused,
this CL fixes the confusing test cases.
Change-Id: I35022e207e2f0d24a23a7f6f188e41ba8eee9886
Reviewed-on: https://go-review.googlesource.com/c/142439
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Akhil Indurti <aindurti@gmail.com>
Reviewed-by: Giovanni Bajo <rasky@develer.com>
In golang.org/cl/75310, the compiler's typechecker was changed so that
map key types were validated at a later stage, to make sure that all the
necessary type information was present.
This still worked for map type declarations, but caused a regression for
top-level map variable declarations. These now caused a fatal panic
instead of a typechecking error.
The cause was that checkMapKeys was run too early, before all
typechecking was done. In particular, top-level map variable
declarations are typechecked as external declarations, much later than
where checkMapKeys was run.
Add a test case for both exported and unexported top-level map
declarations, and add a second call to checkMapKeys at the actual end of
typechecking. Simply moving the one call isn't a good solution either;
the comments expand on that.
Fixes#28058.
Change-Id: Ia5febb01a1d877447cf66ba44fb49a7e0f4f18a5
Reviewed-on: https://go-review.googlesource.com/c/140417
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
x = map[string(byteslice)] is already optimized by the compiler to avoid a
string allocation. This CL generalizes this optimization to:
x = map[T1{ ... Tn{..., string(byteslice), ...} ... }]
where T1 to Tn is a nesting of struct and array literals.
Found in a hot code path that used a struct of strings made from []byte
slices to make a map lookup.
There are no uses of the more generalized optimization in the standard library.
Passes toolstash -cmp.
MapStringConversion/32/simple 21.9ns ± 2% 21.9ns ± 3% ~ (p=0.995 n=17+20)
MapStringConversion/32/struct 28.8ns ± 3% 22.0ns ± 2% -23.80% (p=0.000 n=20+20)
MapStringConversion/32/array 28.5ns ± 2% 21.9ns ± 2% -23.14% (p=0.000 n=19+16)
MapStringConversion/64/simple 21.0ns ± 2% 21.1ns ± 3% ~ (p=0.072 n=19+18)
MapStringConversion/64/struct 72.4ns ± 3% 21.3ns ± 2% -70.53% (p=0.000 n=20+20)
MapStringConversion/64/array 72.8ns ± 1% 21.0ns ± 2% -71.13% (p=0.000 n=17+19)
name old allocs/op new allocs/op delta
MapStringConversion/32/simple 0.00 0.00 ~ (all equal)
MapStringConversion/32/struct 0.00 0.00 ~ (all equal)
MapStringConversion/32/array 0.00 0.00 ~ (all equal)
MapStringConversion/64/simple 0.00 0.00 ~ (all equal)
MapStringConversion/64/struct 1.00 ± 0% 0.00 -100.00% (p=0.000 n=20+20)
MapStringConversion/64/array 1.00 ± 0% 0.00 -100.00% (p=0.000 n=20+20)
Change-Id: I483b4d84d8d74b1025b62c954da9a365e79b7a3a
Reviewed-on: https://go-review.googlesource.com/c/116275
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This change adds codegen tests for the intrinsification on ppc64 of
the OnesCount{64,32,16,8}, and TrailingZeros{64,32,16,8} math/bits
functions.
Change-Id: Id3364921fbd18316850e15c8c71330c906187fdb
Reviewed-on: https://go-review.googlesource.com/c/141897
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Ensure that we correctly type the stack temps for regular closures,
method function closures, and slice literals.
Then we don't need to override the dummy types later.
Furthermore, this allows order to reuse temporaries of these types.
OARRAYLIT doesn't need a temporary as far as I can tell, so I
removed that case from order.
Change-Id: Ic58520fa50c90639393ff78f33d3c831d5c4acb9
Reviewed-on: https://go-review.googlesource.com/c/140306
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This CL adds tests of fused multiplication-accumulation
on arm/arm64.
Change-Id: Ic85d5277c0d6acb7e1e723653372dfaf96824a39
Reviewed-on: https://go-review.googlesource.com/c/141652
Run-TryBot: Ben Shi <powerman1st@163.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Instead of allocating a new temporary each time one
is needed, keep a list of temporaries which are free
(have already been VARKILLed on every path) and use
one of them.
Should save a lot of stack space. In a function like this:
func main() {
fmt.Printf("%d %d\n", 2, 3)
fmt.Printf("%d %d\n", 4, 5)
fmt.Printf("%d %d\n", 6, 7)
}
The three [2]interface{} arrays used to hold the ... args
all use the same autotmp, instead of 3 different autotmps
as happened previous to this CL.
Change-Id: I2d728e226f81e05ae68ca8247af62014a1b032d3
Reviewed-on: https://go-review.googlesource.com/c/140301
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
When we pass these types by reference, we usually have to allocate
temporaries on the stack, initialize them, then pass their address
to the conversion functions. It's simpler to pass these types
directly by value.
This particularly applies to conversions needed for fmt.Printf
(to interface{} for constructing a [...]interface{}).
func f(a, b, c string) {
fmt.Printf("%s %s\n", a, b)
fmt.Printf("%s %s\n", b, c)
}
This function's stack frame shrinks from 200 to 136 bytes, and
its code shrinks from 535 to 453 bytes.
The go binary shrinks 0.3%.
Update #24286
Aside: for this function f, we don't really need to allocate
temporaries for the convT2E function. We could use the address
of a, b, and c directly. That might get similar (or maybe better?)
improvements. I investigated a bit, but it seemed complicated
to do it safely. This change was much easier.
Change-Id: I78cbe51b501fb41e1e324ce4203f0de56a1db82d
Reviewed-on: https://go-review.googlesource.com/c/135377
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Instead of
MOVB go.string."foo"(SB), AX
do
MOVB $102, AX
When we know the global we're loading from is readonly, we can
do that read at compile time.
I've made this arch-dependent mostly because the cases where this
happens often are memory->memory moves, and those don't get
decomposed until lowering.
Did amd64/386/arm/arm64. Other architectures could follow.
Update #26498
Change-Id: I41b1dc831b2cd0a52dac9b97f4f4457888a46389
Reviewed-on: https://go-review.googlesource.com/c/141118
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Do []byte(string) conversions more efficiently when the string
is a constant. Instead of calling stringtobyteslice, allocate
just the space we need and encode the initialization directly.
[]byte("foo") rewrites to the following pseudocode:
var s [3]byte // on heap or stack, depending on whether b escapes
s = *(*[3]byte)(&"foo"[0]) // initialize s from the string
b = s[:]
which generates this assembly:
0x001d 00029 (tmp1.go:9) LEAQ type.[3]uint8(SB), AX
0x0024 00036 (tmp1.go:9) MOVQ AX, (SP)
0x0028 00040 (tmp1.go:9) CALL runtime.newobject(SB)
0x002d 00045 (tmp1.go:9) MOVQ 8(SP), AX
0x0032 00050 (tmp1.go:9) MOVBLZX go.string."foo"+2(SB), CX
0x0039 00057 (tmp1.go:9) MOVWLZX go.string."foo"(SB), DX
0x0040 00064 (tmp1.go:9) MOVW DX, (AX)
0x0043 00067 (tmp1.go:9) MOVB CL, 2(AX)
// Then the slice is b = {AX, 3, 3}
The generated code is still not optimal, as it still does load/store
from read-only memory instead of constant stores. Next CL...
Update #26498Fixes#10170
Change-Id: I4b990b19f9a308f60c8f4f148934acffefe0a5bd
Reviewed-on: https://go-review.googlesource.com/c/140698
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
