Now that the type information is in TYPE instructions
that are not rewritten by the optimization passes,
we don't have to try to preserve the type information
(no longer) attached to MOV instructions.
R=ken2
CC=golang-dev
https://golang.org/cl/7402054
The type information is (and for years has been) included
as an extra field in the address chunk of an instruction.
Unfortunately, suppose there is a string at a+24(FP) and
we have an instruction reading its length. It will say:
MOVQ x+32(FP), AX
and the type of *that* argument is int (not slice), because
it is the length being read. This confuses the picture seen
by debuggers and now, worse, by the garbage collector.
Instead of attaching the type information to all uses,
emit an explicit list of TYPE instructions with the information.
The TYPE instructions are no-ops whose only role is to
provide an address to attach type information to.
For example, this function:
func f(x, y, z int) (a, b string) {
return
}
now compiles into:
--- prog list "f" ---
0000 (/Users/rsc/x.go:3) TEXT f+0(SB),$0-56
0001 (/Users/rsc/x.go:3) LOCALS ,
0002 (/Users/rsc/x.go:3) TYPE x+0(FP){int},$8
0003 (/Users/rsc/x.go:3) TYPE y+8(FP){int},$8
0004 (/Users/rsc/x.go:3) TYPE z+16(FP){int},$8
0005 (/Users/rsc/x.go:3) TYPE a+24(FP){string},$16
0006 (/Users/rsc/x.go:3) TYPE b+40(FP){string},$16
0007 (/Users/rsc/x.go:3) MOVQ $0,b+40(FP)
0008 (/Users/rsc/x.go:3) MOVQ $0,b+48(FP)
0009 (/Users/rsc/x.go:3) MOVQ $0,a+24(FP)
0010 (/Users/rsc/x.go:3) MOVQ $0,a+32(FP)
0011 (/Users/rsc/x.go:4) RET ,
The { } show the formerly hidden type information.
The { } syntax is used when printing from within the gc compiler.
It is not accepted by the assemblers.
The same type information is now included on global variables:
0055 (/Users/rsc/x.go:15) GLOBL slice+0(SB){[]string},$24(AL*0)
This more accurate type information fixes a bug in the
garbage collector's precise heap collection.
The linker only cares about globals right now, but having the
local information should make things a little nicer for Carl
in the future.
Fixes#4907.
R=ken2
CC=golang-dev
https://golang.org/cl/7395056
Change ARM context register to R7, to get out of the way
of the register allocator during the compilation of the
prologue statements (it wants to use R0 as a temporary).
Step 2 of http://golang.org/s/go11func.
R=ken2
CC=golang-dev
https://golang.org/cl/7369048
A new comment directive //go:noescape instructs the compiler
that the following external (no body) func declaration should be
treated as if none of its arguments escape to the heap.
Fixes#4099.
R=golang-dev, dave, minux.ma, daniel.morsing, remyoudompheng, adg, agl, iant
CC=golang-dev
https://golang.org/cl/7289048
If the analysis reached a node twice, then the analysis was cut off.
However, if the second arrival is at a lower depth (closer to escaping)
then it is important to repeat the traversal.
The repeating must be cut off at some point to avoid the occasional
infinite recursion. This CL cuts it off as soon as possible while still
passing all tests.
Fixes#4751.
R=ken2
CC=golang-dev, lvd
https://golang.org/cl/7303043
Expressions involving nil, even if they can be evaluated
at compile time, do not count as Go constants and cannot
be used in const initializers.
Fixes#4673.
Fixes#4680.
R=ken2
CC=golang-dev
https://golang.org/cl/7278043
There's no b in race detector.
The new flag matches the one in the go command
(go test -race math).
R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/7072043
This CL adds a flag parser that matches the semantics of Go's
package flag. It also changes the linkers and compilers to use
the new flag parser.
Command lines that used to work, like
8c -FVw
6c -Dfoo
5g -I/foo/bar
now need to be split into separate arguments:
8c -F -V -w
6c -D foo
5g -I /foo/bar
The new spacing will work with both old and new tools.
The new parser also allows = for arguments, as in
6c -D=foo
5g -I=/foo/bar
but that syntax will not work with the old tools.
In addition to matching standard Go binary flag parsing,
the new flag parser generates more detailed usage messages
and opens the door to long flag names.
The recently added gc flag -= has been renamed -complete.
R=remyoudompheng, daniel.morsing, minux.ma, iant
CC=golang-dev
https://golang.org/cl/7035043
A new environment variable GO386 is introduced to choose between
code generation targeting 387 or SSE2. No auto-detection is
performed and the setting defaults to 387 to preserve previous
behaviour.
The patch is a reorganization of CL6549052 by rsc.
Fixes#3912.
R=minux.ma, rsc
CC=golang-dev
https://golang.org/cl/6962043
An error during the compilation can be more precise
than an error at link time.
For 'func init', the error happens always: you can't forward
declare an init func because the name gets mangled.
For other funcs, the error happens only with the special
(and never used by hand) -= flag, which tells 6g the
package is pure go.
The go command now passes -= for pure Go packages.
Fixes#3705.
R=ken2
CC=golang-dev
https://golang.org/cl/6996054
remove zerostack compiler experiment; will do at link time instead
««« original CL description
cmd/gc: add GOEXPERIMENT=zerostack to clear stack on function entry
This is expensive but it might be useful in cases where
people are suffering from false positives during garbage
collection and are willing to trade the CPU time for getting
rid of the false positives.
On the other hand it only eliminates false positives caused
by other function calls, not false positives caused by dead
temporaries stored in the current function call.
The 5g/6g/8g changes were pulled out of the history, from
the last time we needed to do this (to work around a goto bug).
The code in go.h, lex.c, pgen.c is new but tiny.
R=ken2
CC=golang-dev
https://golang.org/cl/6938073
»»»
R=ken2
CC=golang-dev
https://golang.org/cl/7002051
This is expensive but it might be useful in cases where
people are suffering from false positives during garbage
collection and are willing to trade the CPU time for getting
rid of the false positives.
On the other hand it only eliminates false positives caused
by other function calls, not false positives caused by dead
temporaries stored in the current function call.
The 5g/6g/8g changes were pulled out of the history, from
the last time we needed to do this (to work around a goto bug).
The code in go.h, lex.c, pgen.c is new but tiny.
R=ken2
CC=golang-dev
https://golang.org/cl/6938073
In order to add these, we need to be able to find references
to such types that already exist in the binary. To do that, introduce
a new linker section holding a list of the types corresponding to
arrays, chans, maps, and slices.
To offset the storage cost of this list, and to simplify the code,
remove the interface{} header from the representation of a
runtime type. It was used in early versions of the code but was
made obsolete by the kind field: a switch on kind is more efficient
than a type switch.
In the godoc binary, removing the interface{} header cuts two
words from each of about 10,000 types. Adding back the list of pointers
to array, chan, map, and slice types reintroduces one word for
each of about 500 types. On a 64-bit machine, then, this CL *removes*
a net 156 kB of read-only data from the binary.
This CL does not include the needed support for precise garbage
collection. I have created issue 4375 to track that.
This CL also does not set the 'algorithm' - specifically the equality
and copy functions - for a new array correctly, so I have unexported
ArrayOf for now. That is also part of issue 4375.
Fixes#2339.
R=r, remyoudompheng, mirtchovski, iant
CC=golang-dev
https://golang.org/cl/6572043
This is an experiment in static analysis of Go programs
to understand which struct fields a program might use.
It is not part of the Go language specification, it must
be enabled explicitly when building the toolchain,
and it may be removed at any time.
After building the toolchain with GOEXPERIMENT=fieldtrack,
a specific field can be marked for tracking by including
`go:"track"` in the field tag:
package pkg
type T struct {
F int `go:"track"`
G int // untracked
}
To simplify usage, only named struct types can have
tracked fields, and only exported fields can be tracked.
The implementation works by making each function begin
with a sequence of no-op USEFIELD instructions declaring
which tracked fields are accessed by a specific function.
After the linker's dead code elimination removes unused
functions, the fields referred to by the remaining
USEFIELD instructions are the ones reported as used by
the binary.
The -k option to the linker specifies the fully qualified
symbol name (such as my/pkg.list) of a string variable that
should be initialized with the field tracking information
for the program. The field tracking string is a sequence
of lines, each terminated by a \n and describing a single
tracked field referred to by the program. Each line is made
up of one or more tab-separated fields. The first field is
the name of the tracked field, fully qualified, as in
"my/pkg.T.F". Subsequent fields give a shortest path of
reverse references from that field to a global variable or
function, corresponding to one way in which the program
might reach that field.
A common source of false positives in field tracking is
types with large method sets, because a reference to the
type descriptor carries with it references to all methods.
To address this problem, the CL also introduces a comment
annotation
//go:nointerface
that marks an upcoming method declaration as unavailable
for use in satisfying interfaces, both statically and
dynamically. Such a method is also invisible to package
reflect.
Again, all of this is disabled by default. It only turns on
if you have GOEXPERIMENT=fieldtrack set during make.bash.
R=iant, ken
CC=golang-dev
https://golang.org/cl/6749064
- make sure dclcontext == PAUTO only in function bodies
- introduce PDISCARD to discard declarations in bodies of repeated imports
- skip printing initializing OAS'es in export mode, assuming they only occur after ODCL's
- remove ODCL and the initializing OAS from inl.c:ishairy
- fix confused use of ->typecheck in typecheckinl: it's about the ->inl, not about the fn.
- debuging aids: print ntype on ONAMEs too and -Emm instead of -Ell.
fixes#2812
R=rsc
CC=golang-dev
https://golang.org/cl/6800043
includes step 0: synthesize outparams, from 6600044
includes step 1,2: give outparams loopdepth 0 and verify unchanged results
generate esc:$mask tags, but still tie to sink if a param has mask != 0
from 6610054
adds final steps:
- have esccall generate n->escretval, a list of nodes the function results flow to
- use these in esccall and ORETURN/OAS2FUNC/and f(g())
- only tie parameters to sink if tag is absent, otherwise according to mask, tie them to escretval
R=rsc, bradfitz
CC=dave, gobot, golang-dev, iant, rsc
https://golang.org/cl/6741044
includes step 0: synthesize outparams, from 6600044
step 1: give outparams loopdepth 0 and verify unchanged results
step 2: generate esc:$mask tags, but still tie to sink if a param has mask != 0
next step: use in esccall (and ORETURN with implicit OAS2FUNC) to avoid tying to sink
R=rsc
CC=golang-dev
https://golang.org/cl/6610054
Someone new to the language may not know the connection between ints and arrays, which was the only thing that the previous error told you anything about.
Fixes#4256.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6739048
The protection against segfaults does not completely solve
crashes and breaks test/fixedbugs/bug365.go
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6615058
This is the first part of a bigger change that adds data race detection feature:
https://golang.org/cl/6456044
This change makes gc compiler instrument memory accesses when supplied with -b flag.
R=rsc, nigeltao, lvd
CC=golang-dev
https://golang.org/cl/6497074
This CL makes the compiler understand that the type of
the len or cap of a map, slice, or string is 'int', not 'int32'.
It does not change the meaning of int, but it should make
the eventual change of the meaning of int in 6g a bit smoother.
Update #2188.
R=ken, dave, remyoudompheng
CC=golang-dev
https://golang.org/cl/6542059
There may be further savings if convT2I can avoid the function call
if the cache is good and T is uintptr-shaped, a la convT2E, but that
will be a follow-up CL.
src/pkg/runtime:
benchmark old ns/op new ns/op delta
BenchmarkConvT2ISmall 43 15 -64.01%
BenchmarkConvT2IUintptr 45 14 -67.48%
BenchmarkConvT2ILarge 130 101 -22.31%
test/bench/go1:
benchmark old ns/op new ns/op delta
BenchmarkBinaryTree17 8588997000 8499058000 -1.05%
BenchmarkFannkuch11 5300392000 5358093000 +1.09%
BenchmarkGobDecode 30295580 31040190 +2.46%
BenchmarkGobEncode 18102070 17675650 -2.36%
BenchmarkGzip 774191400 771591400 -0.34%
BenchmarkGunzip 245915100 247464100 +0.63%
BenchmarkJSONEncode 123577000 121423050 -1.74%
BenchmarkJSONDecode 451969800 596256200 +31.92%
BenchmarkMandelbrot200 10060050 10072880 +0.13%
BenchmarkParse 10989840 11037710 +0.44%
BenchmarkRevcomp 1782666000 1716864000 -3.69%
BenchmarkTemplate 798286600 723234400 -9.40%
R=rsc, bradfitz, go.peter.90, daniel.morsing, dave, uriel
CC=golang-dev
https://golang.org/cl/6337058
CL 4313064 fixed its test case but did not address a
general enough problem:
type T1 struct { F *T2 }
type T2 T1
type T3 T2
could still end up copying the definition of T1 for T2
before T1 was done being evaluated, or T3 before T2
was done.
In order to propagate the updates correctly,
record a copy of an incomplete type for re-execution
once the type is completed. Roll back CL 4313064.
Fixes#3709.
R=ken2
CC=golang-dev, lstoakes
https://golang.org/cl/6301059
Drop expecttaken function in favor of extra argument
to gbranch and bgen. Mark loop condition as likely to
be true, so that loops are generated inline.
The main benefit here is contiguous code when trying
to read the generated assembly. It has only minor effects
on the timing, and they mostly cancel the minor effects
that aligning function entry points had. One exception:
both changes made Fannkuch faster.
Compared to before CL 6244066 (before aligned functions)
benchmark old ns/op new ns/op delta
BenchmarkBinaryTree17 4222117400 4201958800 -0.48%
BenchmarkFannkuch11 3462631800 3215908600 -7.13%
BenchmarkGobDecode 20887622 20899164 +0.06%
BenchmarkGobEncode 9548772 9439083 -1.15%
BenchmarkGzip 151687 152060 +0.25%
BenchmarkGunzip 8742 8711 -0.35%
BenchmarkJSONEncode 62730560 62686700 -0.07%
BenchmarkJSONDecode 252569180 252368960 -0.08%
BenchmarkMandelbrot200 5267599 5252531 -0.29%
BenchmarkRevcomp25M 980813500 985248400 +0.45%
BenchmarkTemplate 361259100 357414680 -1.06%
Compared to tip (aligned functions):
benchmark old ns/op new ns/op delta
BenchmarkBinaryTree17 4140739800 4201958800 +1.48%
BenchmarkFannkuch11 3259914400 3215908600 -1.35%
BenchmarkGobDecode 20620222 20899164 +1.35%
BenchmarkGobEncode 9384886 9439083 +0.58%
BenchmarkGzip 150333 152060 +1.15%
BenchmarkGunzip 8741 8711 -0.34%
BenchmarkJSONEncode 65210990 62686700 -3.87%
BenchmarkJSONDecode 249394860 252368960 +1.19%
BenchmarkMandelbrot200 5273394 5252531 -0.40%
BenchmarkRevcomp25M 996013800 985248400 -1.08%
BenchmarkTemplate 360620840 357414680 -0.89%
R=ken2
CC=golang-dev
https://golang.org/cl/6245069
* Eliminate bounds check on known small shifts.
* Rewrite x<<s | x>>(32-s) as a rotate (constant s).
* More aggressive (but still minimal) range analysis.
R=ken, dave, iant
CC=golang-dev
https://golang.org/cl/6209077
I tried before to make relative imports work by simply
invoking the compiler in the right directory, so that
an import of ./foo could be resolved by ./foo.a.
This required creating a separate tree of package binaries
that included the full path to the source directory, so that
/home/gopher/bar.go would be compiled in
tmpdir/work/local/home/gopher and perhaps find
a ./foo.a in that directory.
This model breaks on Windows because : appears in path
names but cannot be used in subdirectory names, and I
missed one or two places where it needed to be removed.
The model breaks more fundamentally when compiling
a test of a package that lives outside the Go path, because
we effectively use a ./ import in the generated testmain,
but there we want to be able to resolve the ./ import
of the test package to one directory and all the other ./
imports to a different directory. Piggybacking on the compiler's
current working directory is then no longer possible.
Instead, introduce a new compiler option -D prefix that
makes the compiler turn a ./ import into prefix+that,
so that import "./foo" with -D a/b/c turns into import
"a/b/c/foo". Then we can invent a package hierarchy
"_/" with subdirectories named for file system paths:
import "./foo" in the directory /home/gopher becomes
import "_/home/gopher/foo", and since that final path
is just an ordinary import now, all the ordinary processing
works, without special cases.
We will have to change the name of the hierarchy if we
ever decide to introduce a standard package with import
path "_", but that seems unlikely, and the detail is known
only in temporary packages that get thrown away at the
end of a build.
Fixes#3169.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5732045
Also allow multiple invalid import statements in a
single file.
Fixes#3021. The changes to go/parser and the
language specifcation have already been committed.
R=rsc, gri
CC=golang-dev
https://golang.org/cl/5672084
