This is joint work with Daniel Morsing.
In order for the register allocator to alias two variables, they must have the same width, stack offset, and etype. Code generation was altering a variable's etype in a few places. This prevented the variable from being moved to a register, which in turn prevented peephole optimization. This failure to alias was very common, with almost 23,000 instances just running make.bash.
This phenomenon was not visible in the register allocation debug output because the variables that failed to alias had the same name. The debugging-only change to bits.c fixes this by printing the variable number with its name.
This CL fixes the source of all etype mismatches for 6g, all but one case for 8g, and depressingly few cases for 5g. (I believe that extending CL 6819083 to 5g is a prerequisite.) Fixing the remaining cases in 8g and 5g is work for the future.
The etype mismatch fixes are:
* [gc] Slicing changed the type of the base pointer into a uintptr in order to perform arithmetic on it. Instead, support addition directly on pointers.
* [*g] OSPTR was giving type uintptr to slice base pointers; undo that. This arose, for example, while compiling copy(dst, src).
* [8g] 64 bit float conversion was assigning int64 type during codegen, overwriting the existing uint64 type.
Note that some etype mismatches are appropriate, such as a struct with a single field or an array with a single element.
With these fixes, the number of registerizations that occur while running make.bash for 6g increases ~10%. Hello world binary size shrinks ~1.5%. Running all benchmarks in the standard library show performance improvements ranging from nominal to substantive (>10%); a full comparison using 6g on my laptop is available at https://gist.github.com/josharian/8f9b5beb46667c272064. The microbenchmarks must be taken with a grain of salt; see issue 7920. The few benchmarks that show real regressions are likely due to issue 7920. I manually examined the generated code for the top few regressions and none had any assembly output changes. The few benchmarks that show extraordinary improvements are likely also due to issue 7920.
Performance results from 8g appear similar to 6g.
5g shows no performance improvements. This is not surprising, given the discussion above.
Update #7316
LGTM=rsc
R=rsc, daniel.morsing, bradfitz
CC=dave, golang-codereviews
https://golang.org/cl/91850043
The runtime was detecting the cycle already,
but we can give a better error without even
building the binary.
Fixes#7789.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/96290043
This change requires using SWIG version 3.0 or later. Earlier
versions of SWIG do not generate the pragmas required to use
the external linker.
Fixes#7155.
Fixes#7156.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/97120046
Before we used line 1 of the first source file.
This should be clearer.
Fixes#4388.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/92250044
This is a trivial change to make use of an existing `nl` byte slice
containing a single '\n' character. It's already declared and
used in another place in this file, so it might as well be used
in the other location instead of
a new slice literal. There should be no change in behavior,
aside from potentially less allocations.
This is my first CL, so I wanted to use a simple, hopefully non-controversial,
minor improvement to get more comfortable with golang contribution process.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/97280043
list has been adding them one at a time haphazardly
(race and tags were there and documented; compiler
was there and undocumented).
clean -i needs -compiler in order to clean the
installed targets for alternate compilers.
Fixes#7302.
While we're here, tweak the language in the 'go get' docs
about build flags.
Fixes#7807.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/99130043
If you write:
var x = 3
then the compiler arranges for x to be initialized in the linker
with an actual 3 from the data segment, rather than putting
x in the bss and emitting init-time "x = 3" assignment code.
If you write:
var y = x
var x = 3
then the compiler is clever and treats this the same as if
the code said 'y = 3': they both end up in the data segment
with no init-time assignments.
If you write
var y = x
var x int
then the compiler was treating this the same as if the
code said 'x = 0', making both x and y zero and avoiding
any init-time assignment.
This copying optimization to avoid init-time assignment of y
is incorrect if 'var x int' doesn't mean 'x = 0' but instead means
'x is initialized in C or assembly code'. The program ends up
with 'y = 0' instead of 'y = the value specified for x in that other code'.
Disable the propagation if there is no initializer for x.
This comes up in some uses of cgo, because cgo generates
Go globals that are initialized in accompanying C files.
Fixes#7665.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/93200044
If the ... element type contained no pointers,
then the escape analysis did not track the ... itself.
This manifested in an escaping ...byte being treated
as non-escaping.
Fixes#7934.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/100310043
The register allocator decides which variables should be placed into registers by charging for each load/store and crediting for each use, and then selecting an allocation with minimal cost. NOPs will be eliminated, however, so using a variable in a NOP should not generate credit.
Issue 7867 arises from attempted registerization of multi-word variables because they are used in NOPs. By not crediting for that use, they will no longer be considered for registerization.
This fix could theoretically lead to better register allocation, but NOPs are rare relative to other instructions.
Fixes#7867.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/94810044
Where the spelling changed from British to
US norm (e.g., optimise -> optimize) it follows
the style in that file.
LGTM=adonovan
R=golang-codereviews, adonovan
CC=golang-codereviews
https://golang.org/cl/96980043
This change allows us to give an hg tag such as "go1.3beta1" to
revisions in the main branch without breaking the build.
This is helpful for community members who want to build the beta
from source.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/90190044
go test may call builder.init() multiple times which will create a new work directory. The cleanup needs to hoist the current work directory.
Fixes#7904.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/95900044
For gccgo we rename exported functions so that the compiler
will make them visible. This CL adds a #define so that C
functions that #include "cgo_export.h" can use the expected
names of the function.
The test for this is the existing issue6833 test in
misc/cgo/test. Without this CL it fails when using
-compiler=gccgo.
LGTM=minux.ma, rsc
R=golang-codereviews, gobot, rsc, minux.ma
CC=golang-codereviews
https://golang.org/cl/91830046
Previously we used strndup(3) to implement C.CString for gccgo. This
is wrong because strndup assumes the string to be null terminated,
and stops at the first null terminator. Instead, use malloc
and memmove to create a copy of the string, as we do in the
gc implementation.
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/96790047
This should have been part of 36eb4a62fbb6,
but I later discovered that addresses are all wrong.
Appropriate test added now.
LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/89470043
CL 89050043 only allows -ccflags for 'go test', this
CL really handles the flag like the other -??flags.
Many thanks to Dobrosław Żybort for pointing this out.
Fixes#7810 (again).
LGTM=iant, matrixik
R=golang-codereviews, iant, matrixik
CC=golang-codereviews
https://golang.org/cl/89230044
following on CL https://golang.org/cl/76810045 and
issue 7563, i now see there's another "remove(outfile)" a few
dozen lines down that also needs fixing.
LGTM=iant
R=golang-codereviews, iant
CC=0intro, golang-codereviews, r
https://golang.org/cl/89030043
It is possible to use ./ imports on Windows but it
requires some extra command-line work
('go build' does this automatically, but we can't use 'go build' here).
Instead, use an ordinary import and -I/-L, which are easier to use.
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/89040043
Variables declared with 'var' have no sym->def.
Fixes#7794.
LGTM=rsc
R=golang-codereviews, bradfitz, rsc
CC=golang-codereviews
https://golang.org/cl/88360043
Before the switch to liblink, the linkers accepted the -c flag
to print the call graph. This change restores the functionality.
This came in handy when I was trying to audit the use of SSE
instructions inside the Plan 9 note handler.
LGTM=rsc
R=golang-codereviews, bradfitz, rsc
CC=golang-codereviews
https://golang.org/cl/73990043
https://golang.org/cl/60590044 edited
doc.go without editing the file it is generated from.
The edit was lost at the next mkdoc.sh.
Make the change in help.go and rerun mkdoc.sh.
Pointed out in the review of CL 68580043.
TBR=iant
CC=golang-codereviews
https://golang.org/cl/88760043
The new code is adapted from the Go 1.2 nosplit code,
but it does not have the bug reported in issue 7623:
g% go run nosplit.go
g% go1.2 run nosplit.go
BUG
rejected incorrectly:
main 0 call f; f 120
linker output:
# _/tmp/go-test-nosplit021064539
main.main: nosplit stack overflow
120 guaranteed after split check in main.main
112 on entry to main.f
-8 after main.f uses 120
g%
Fixes#6931.
Fixes#7623.
LGTM=iant
R=golang-codereviews, iant, ality
CC=golang-codereviews, r
https://golang.org/cl/88190043
The name linkwriteobj is misleading because it implies that
the function has something to do with the linker, which it
does not. The name is historical: the function performs an
operation that was previously performed by the linker, but no
longer is.
LGTM=rsc
R=rsc, minux.ma
CC=golang-codereviews
https://golang.org/cl/88210045
Without the leaf bit, the linker cannot record
the correct frame size in the symbol table, and
then stack traces get mangled. (Only for ARM.)
Fixes#7338.
Fixes#7347.
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/88550043
In large functions with many variables, the register optimizer
may give up and choose not to track certain variables at all.
In this case, the "nextinnode" information linking together
all the words from a given variable will be incomplete, and
the result may be that only some of a multiword value is
preserved across a call. That confuses the garbage collector,
so don't do that. Instead, mark those variables as having
their address taken, so that they will be preserved at all
calls. It's overkill, but correct.
Tested by hand using the 6g -S output to see that it does fix
the buggy generated code leading to the issue 7726 failure.
There is no automated test because I managed to break the
compiler while writing a test (see issue 7727). I will check
in a test along with the fix to issue 7727.
Fixes#7726.
LGTM=khr
R=khr, bradfitz, dave
CC=golang-codereviews
https://golang.org/cl/85200043
linklookup uses hash(name, v) as the hash table index but then
only compares name to find a symbol to return.
If hash(name, v1) == hash(name, v2) for v1 != v2, the lookup
for v2 will return the symbol with v1.
The input routines assume that each symbol is found only once,
and then each symbol is added to a linked list, with the list header
in the symbol. Adding a symbol to such a list multiple times
short-circuits the list the second time it is added, causing symbols
to be dropped.
The liblink rewrite introduced an elegant, if inefficient, handling
of duplicated symbols by creating a dummy symbol to read the
duplicate into. The dummy symbols are named .dup with
sequential version numbers. With many .dup symbols, eventually
there will be a conflict, causing a duplicate list add, causing elided
symbols, causing a crash when calling one of the elided symbols.
The bug is old (2011) but could not have manifested until the
liblink rewrite introduced this heavily duplicated symbol .dup.
(See History section below.)
1. Correct the lookup function.
2. Since we want all the .dup symbols to be different, there's no
point in inserting them into the table. Call linknewsym directly,
avoiding the lookup function entirely.
3. Since nothing can refer to the .dup symbols, do not bother
adding them to the list of functions (textp) at all.
4. In lieu of a unit test, introduce additional consistency checks to
detect adding a symbol to a list multiple times. This would have
caught the short-circuit more directly, and it will detect a variety
of double-use bugs, including the one arising from the bad lookup.
Fixes#7749.
History
On April 9, 2011, I submitted CL 4383047, making ld 25% faster.
Much of the focus was on the hash table lookup function, and
one of the changes was to remove the s->version == v comparison [1].
I don't know if this was a simple editing error or if I reasoned that
same name but different v would yield a different hash slot and
so the name test alone sufficed. It is tempting to claim the former,
but it was probably the latter.
Because the hash is an iterated multiply+add, the version ends up
adding v*3ⁿ to the hash, where n is the length of the name.
A collision would need x*3ⁿ ≡ y*3ⁿ (mod 2²⁴ mod 100003),
or equivalently x*3ⁿ ≡ x*3ⁿ + (y-x)*3ⁿ (mod 2²⁴ mod 100003),
so collisions will actually be periodic: versions x and y collide
when d = y-x satisfies d*3ⁿ ≡ 0 (mod 2²⁴ mod 100003).
Since we allocate version numbers sequentially, this is actually
about the best case one could imagine: the collision rate is
much lower than if the hash were more random.
http://play.golang.org/p/TScD41c_hA computes the collision
period for various name lengths.
The most common symbol in the new linker is .dup, and for n=4
the period is maximized: the 100004th symbol is the first collision.
Unfortunately, there are programs with more duplicated symbols
than that.
In Go 1.2 and before, duplicate symbols were handled without
creating a dummy symbol, so this particular case for generating
many duplicate symbols could not happen. Go does not use
versioned symbols. Only C does; each input file gives a different
version to its static declarations. There just aren't enough C files
for this to come up in that context.
So the bug is old but the realization of the bug is new.
[1] https://golang.org/cl/4383047/diff/5001/src/cmd/ld/lib.c
LGTM=minux.ma, iant, dave
R=golang-codereviews, minux.ma, bradfitz, iant, dave
CC=golang-codereviews, r
https://golang.org/cl/87910047
This code never got updated after the liblink shuffle.
Tested by hand that it works and respects GOROOT_FINAL.
The discussion in issue 6963 suggests that perhaps we should
just drop runtime-gdb.py entirely, but I am not convinced
that is true. It was in Go 1.2 and I don't see a reason not to
keep it in Go 1.3. The fact that binaries have not been emitting
the reference was just a missed detail in the liblink conversion,
not part of a grand plan.
Fixes#7506.
Fixes#6963.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews, iant, r
https://golang.org/cl/87870048
If we compile a generated file stored in a temporary
directory - let's say /tmp/12345/work/x.c - then by default
6c stores the full path and then the pcln table in the
final binary includes the full path. This makes repeated builds
(using different temporary directories) produce different
binaries, even if the inputs are the same.
In the old 'go tool pack', the P flag specified a prefix to remove
from all stored paths (if present), and cmd/go invoked
'go tool pack grcP $WORK' to remove references to the
temporary work directory.
We've changed the build to avoid pack as much as possible,
under the theory that instead of making pack convert from
.6 to .a, the tools should just write the .a directly and save a
round of I/O.
Instead of going back to invoking pack always, define a common
flag -trimpath in the assemblers, C compilers, and Go compilers,
implemented in liblink, and arrange for cmd/go to use the flag.
Then the object files being written out have the shortened paths
from the start.
While we are here, reimplement pcln support for GOROOT_FINAL.
A build in /tmp/go uses GOROOT=/tmp/go, but if GOROOT_FINAL=/usr/local/go
is set, then a source file named /tmp/go/x.go is recorded instead as
/usr/local/go/x.go. We use this so that we can prepare distributions
to be installed in /usr/local/go without actually working in that
directory. The conversion to liblink deleted all the old file name
handling code, including the GOROOT_FINAL translation.
Bring the GOROOT_FINAL translation back.
Before this CL, using GOROOT_FINAL=/goroot make.bash:
g% strings $(which go) | grep -c $TMPDIR
6
g% strings $(which go) | grep -c $GOROOT
793
g%
After this CL:
g% strings $(which go) | grep -c $TMPDIR
0
g% strings $(which go) | grep -c $GOROOT
0
g%
(The references to $TMPDIR tend to be cgo-generated source files.)
Adding the -trimpath flag to the assemblers required converting
them to the new Go-semantics flag parser. The text in go1.3.html
is copied and adjusted from go1.1.html, which is when we applied
that conversion to the compilers and linkers.
Fixes#6989.
LGTM=iant
R=r, iant
CC=golang-codereviews
https://golang.org/cl/88300045
My cmd/go got in a weird state where it started invoking pack grcP.
Change pack to print a 1-line explanation of the usage problem
before the generic usage message.
LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/87770047
OpenBSD is excluded from all the usual thread-local storage
code, not just emitting the tbss section in the external link .o
but emitting a PT_TLS section in an internally-linked executable.
I assume it just has no proper TLS support. Exclude it here too.
TBR=iant
CC=golang-codereviews
https://golang.org/cl/87900045
When I did the original 386 ports on Linux and OS X, I chose to
define GS-relative expressions like 4(GS) as relative to the actual
thread-local storage base, which was usually GS but might not be
(it might be FS, or it might be a different constant offset from GS or FS).
The original scope was limited but since then the rewrites have
gotten out of control. Sometimes GS is rewritten, sometimes FS.
Some ports do other rewrites to enable shared libraries and
other linking. At no point in the code is it clear whether you are
looking at the real GS/FS or some synthesized thing that will be
rewritten. The code manipulating all these is duplicated in many
places.
The first step to fixing issue 7719 is to make the code intelligible
again.
This CL adds an explicit TLS pseudo-register to the 386 and amd64.
As a register, TLS refers to the thread-local storage base, and it
can only be loaded into another register:
MOVQ TLS, AX
An offset from the thread-local storage base is written off(reg)(TLS*1).
Semantically it is off(reg), but the (TLS*1) annotation marks this as
indexing from the loaded TLS base. This emits a relocation so that
if the linker needs to adjust the offset, it can. For example:
MOVQ TLS, AX
MOVQ 8(AX)(TLS*1), CX // load m into CX
On systems that support direct access to the TLS memory, this
pair of instructions can be reduced to a direct TLS memory reference:
MOVQ 8(TLS), CX // load m into CX
The 2-instruction and 1-instruction forms correspond roughly to
ELF TLS initial exec mode and ELF TLS local exec mode, respectively.
Liblink applies this rewrite on systems that support the 1-instruction form.
The decision is made using only the operating system (and probably
the -shared flag, eventually), not the link mode. If some link modes
on a particular operating system require the 2-instruction form,
then all builds for that operating system will use the 2-instruction
form, so that the link mode decision can be delayed to link time.
Obviously it is late to be making changes like this, but I despair
of correcting issue 7719 and issue 7164 without it. To make sure
I am not changing existing behavior, I built a "hello world" program
for every GOOS/GOARCH combination we have and then worked
to make sure that the rewrite generates exactly the same binaries,
byte for byte. There are a handful of TODOs in the code marking
kludges to get the byte-for-byte property, but at least now I can
explain exactly how each binary is handled.
The targets I tested this way are:
darwin-386
darwin-amd64
dragonfly-386
dragonfly-amd64
freebsd-386
freebsd-amd64
freebsd-arm
linux-386
linux-amd64
linux-arm
nacl-386
nacl-amd64p32
netbsd-386
netbsd-amd64
openbsd-386
openbsd-amd64
plan9-386
plan9-amd64
solaris-amd64
windows-386
windows-amd64
There were four exceptions to the byte-for-byte goal:
windows-386 and windows-amd64 have a time stamp
at bytes 137 and 138 of the header.
darwin-386 and plan9-386 have five or six modified
bytes in the middle of the Go symbol table, caused by
editing comments in runtime/sys_{darwin,plan9}_386.s.
Fixes#7164.
LGTM=iant
R=iant, aram, minux.ma, dave
CC=golang-codereviews
https://golang.org/cl/87920043
This breaks "go get -d repo/path/...".
««« original CL description
cmd/go: do not miss an error if import path contains "cmd/something"
Fixes#7638
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/87300043
»»»
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/87890043
The relocation and automatic variable types were using
arch-specific numbers. Introduce portable enumerations
instead.
To the best of my knowledge, these are the only arch-specific
bits left in the new object file format.
Remove now, before Go 1.3, because file formats are forever.
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/87670044
There are changes we know we want to make, but not before Go 1.3
Add a version number so that we can make them more easily later.
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/87670043
These are not ready and will not be in Go 1.3.
Fixes#6932.
LGTM=bradfitz
R=golang-codereviews, bradfitz, minux.ma
CC=golang-codereviews, iant, r
https://golang.org/cl/87630043
We have never released cmd/prof and don't plan to.
Now that nm, addr2line, and objdump have been rewritten in Go,
cmd/prof is the only thing keeping us from deleting libmach.
Delete cmd/prof, and then since nothing is using libmach, delete libmach.
13,000 lines of C deleted.
LGTM=minux.ma
R=golang-codereviews, minux.ma
CC=golang-codereviews, iant, r
https://golang.org/cl/87020044
Update cmd/dist not to build the C version.
Update cmd/go to install the Go version to the tool directory.
Update #7452
This is the basic logic needed for objdump, and it works well enough
to support the pprof list and weblist commands. A real disassembler
needs to be added in order to support the pprof disasm command
and the per-line assembly displays in weblist. That's still to come.
Probably objdump will move to go.tools when the disassembler
is added, but it can stay here for now.
LGTM=minux.ma
R=golang-codereviews, minux.ma
CC=golang-codereviews, iant, r
https://golang.org/cl/87580043
even when there are no *_test.go files present.
rsc suggested this change
Fixes#7108
LGTM=r, adg
R=golang-codereviews, r, adg
CC=golang-codereviews
https://golang.org/cl/84300043
On amd64p32 pointers are 32-bit-aligned and cannot be assumed to
have an offset multiple of widthreg. Instead check that they are
withptr-aligned.
Also change the threshold for region merging to 2*widthreg
instead of 2*widthptr because performance on amd64 and amd64p32
is expected to be the same.
Fixes#7712.
LGTM=khr
R=rsc, dave, khr, brad, bradfitz
CC=golang-codereviews
https://golang.org/cl/84690044
Add a $Context variable to the template so that the build.Context values
such as BuildTags can be accessed.
Fixes#6666.
LGTM=adg, rsc
R=golang-codereviews, gobot, adg, rsc
CC=golang-codereviews
https://golang.org/cl/72770043
Native Client forbids jumps/calls to arbitrary locations and
enforces a particular alignement, which makes the Duff's device
ineffective.
LGTM=khr
R=rsc, dave, khr
CC=golang-codereviews
https://golang.org/cl/84400043
Trying to make GODEBUG=gcdead=1 work with liveness
and in particular ambiguously live variables.
1. In the liveness computation, mark all ambiguously live
variables as live for the entire function, except the entry.
They are zeroed directly after entry, and we need them not
to be poisoned thereafter.
2. In the liveness computation, compute liveness (and deadness)
for all parameters, not just pointer-containing parameters.
Otherwise gcdead poisons untracked scalar parameters and results.
3. Fix liveness debugging print for -live=2 to use correct bitmaps.
(Was not updated for compaction during compaction CL.)
4. Correct varkill during map literal initialization.
Was killing the map itself instead of the inserted value temp.
5. Disable aggressive varkill cleanup for call arguments if
the call appears in a defer or go statement.
6. In the garbage collector, avoid bug scanning empty
strings. An empty string is two zeros. The multiword
code only looked at the first zero and then interpreted
the next two bits in the bitmap as an ordinary word bitmap.
For a string the bits are 11 00, so if a live string was zero
length with a 0 base pointer, the poisoning code treated
the length as an ordinary word with code 00, meaning it
needed poisoning, turning the string into a poison-length
string with base pointer 0. By the same logic I believe that
a live nil slice (bits 11 01 00) will have its cap poisoned.
Always scan full multiword struct.
7. In the runtime, treat both poison words (PoisonGC and
PoisonStack) as invalid pointers that warrant crashes.
Manual testing as follows:
- Create a script called gcdead on your PATH containing:
#!/bin/bash
GODEBUG=gcdead=1 GOGC=10 GOTRACEBACK=2 exec "$@"
- Now you can build a test and then run 'gcdead ./foo.test'.
- More importantly, you can run 'go test -short -exec gcdead std'
to run all the tests.
Fixes#7676.
While here, enable the precise scanning of slices, since that was
disabled due to bugs like these. That now works, both with and
without gcdead.
Fixes#7549.
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/83410044
runtime.Version() requires a trailing "+" when
tree had local modifications at time of build.
Fixes#7701
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/84040045
Brad has been asking for this for a while.
I have resisted because I wanted to find a more general way to
do this, one that would keep the performance of code introducing
variables the same as the performance of code that did not.
(See golang.org/issue/3512#c20).
I have not found the more general way, and recent changes to
remove ambiguously live temporaries have blown away the
property I was trying to preserve, so that's no longer a reason
not to make the change.
Fixes#3512.
LGTM=iant
R=iant
CC=bradfitz, golang-codereviews, khr, r
https://golang.org/cl/83740044
Cuts hello world by 70kB, because we don't write
those names into the symbol table.
Update #6853
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/80370045
The data field is the generic array that acts as a standin
for the keys and values arrays for the generic runtime code.
We want to substitute the keys and values arrays for the data
array, not just add keys and values in addition to it.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/81160044
Darwin 10.6 (gcc 4.2) and some older versions of gcc default to C90 mode, not C99 mode. Silence the warning.
LGTM=aram, iant
R=golang-codereviews, aram, iant
CC=golang-codereviews
https://golang.org/cl/83090050
Reduce footprint of liveness bitmaps by about 5x.
1. Mark all liveness bitmap symbols as 4-byte aligned
(they were aligned to a larger size by default).
2. The bitmap data is a bitmap count n followed by n bitmaps.
Each bitmap begins with its own count m giving the number
of bits. All the m's are the same for the n bitmaps.
Emit this bitmap length once instead of n times.
3. Many bitmaps within a function have the same bit values,
but each call site was given a distinct bitmap. Merge duplicate
bitmaps so that no bitmap is written more than once.
4. Many functions end up with the same aggregate bitmap data.
We used to name the bitmap data funcname.gcargs and funcname.gclocals.
Instead, name it gclocals.<md5 of data> and mark it dupok so
that the linker coalesces duplicate sets. This cut the bitmap
data remaining after step 3 by 40%; I was not expecting it to
be quite so dramatic.
Applied to "go build -ldflags -w code.google.com/p/go.tools/cmd/godoc":
bitmaps pclntab binary on disk
before this CL 1326600 1985854 12738268
4-byte align 1154288 (0.87x) 1985854 (1.00x) 12566236 (0.99x)
one bitmap len 782528 (0.54x) 1985854 (1.00x) 12193500 (0.96x)
dedup bitmap 414748 (0.31x) 1948478 (0.98x) 11787996 (0.93x)
dedup bitmap set 245580 (0.19x) 1948478 (0.98x) 11620060 (0.91x)
While here, remove various dead blocks of code from plive.c.
Fixes#6929.
Fixes#7568.
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/83630044
warning: src/cmd/8g/ggen.c:35 non-interruptable temporary
warning: src/cmd/gc/walk.c:656 set and not used: l
warning: src/cmd/gc/walk.c:658 set and not used: l
LGTM=minux.ma
R=golang-codereviews, minux.ma
CC=golang-codereviews
https://golang.org/cl/83660043
1. Use n->alloc, not n->left, to hold the allocated temp being
passed from orderstmt/orderexpr to walk.
2. Treat method values the same as closures.
3. Use killed temporary for composite literal passed to
non-escaping function argument.
4. Clean temporaries promptly in if and for statements.
5. Clean temporaries promptly in select statements.
As part of this, move all the temporary-generating logic
out of select.c into order.c, so that the temporaries can
be reclaimed.
With the new temporaries, can re-enable the 1-entry
select optimization. Fixes issue 7672.
While we're here, fix a 1-line bug in select processing
turned up by the new liveness test (but unrelated; select.c:72).
Fixes#7686.
6. Clean temporaries (but not particularly promptly) in switch
and range statements.
7. Clean temporary used during convT2E/convT2I.
8. Clean temporaries promptly during && and || expressions.
---
CL 81940043 reduced the number of ambiguously live temps
in the godoc binary from 860 to 711.
CL 83090046 reduced the number from 711 to 121.
This CL reduces the number from 121 to 23.
15 the 23 that remain are in fact ambiguously live.
The final 8 could be fixed but are not trivial and
not common enough to warrant work at this point
in the release cycle.
These numbers only count ambiguously live temps,
not ambiguously live user-declared variables.
There are 18 such variables in the godoc binary after this CL,
so a total of 41 ambiguously live temps or user-declared
variables.
The net effect is that zeroing anything on entry to a function
should now be a rare event, whereas earlier it was the
common case.
This is good enough for Go 1.3, and probably good
enough for future releases too.
Fixes#7345.
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/83000048
1. In functions with heap-allocated result variables or with
defer statements, the return sequence requires more than
just a single RET instruction. There is an optimization that
arranges for all returns to jump to a single copy of the return
epilogue in this case. Unfortunately, that optimization is
fundamentally incompatible with PC-based liveness information:
it takes PCs at many different points in the function and makes
them all land at one PC, making the combined liveness information
at that target PC a mess. Disable this optimization, so that each
return site gets its own copy of the 'call deferreturn' and the
copying of result variables back from the heap.
This removes quite a few spurious 'ambiguously live' variables.
2. Let orderexpr allocate temporaries that are passed by address
to a function call and then die on return, so that we can arrange
an appropriate VARKILL.
2a. Do this for ... slices.
2b. Do this for closure structs.
2c. Do this for runtime.concatstring, which is the implementation
of large string additions. Change representation of OADDSTR to
an explicit list in typecheck to avoid reconstructing list in both
walk and order.
3. Let orderexpr allocate the temporary variable copies used for
range loops, so that they can be killed when the loop is over.
Similarly, let it allocate the temporary holding the map iterator.
CL 81940043 reduced the number of ambiguously live temps
in the godoc binary from 860 to 711.
This CL reduces the number to 121. Still more to do, but another
good checkpoint.
Update #7345
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/83090046
REP MOVSQ and REP STOSQ have a really high startup overhead.
Use a Duff's device to do the repetition instead.
benchmark old ns/op new ns/op delta
BenchmarkClearFat32 7.20 1.60 -77.78%
BenchmarkCopyFat32 6.88 2.38 -65.41%
BenchmarkClearFat64 7.15 3.20 -55.24%
BenchmarkCopyFat64 6.88 3.44 -50.00%
BenchmarkClearFat128 9.53 5.34 -43.97%
BenchmarkCopyFat128 9.27 5.56 -40.02%
BenchmarkClearFat256 13.8 9.53 -30.94%
BenchmarkCopyFat256 13.5 10.3 -23.70%
BenchmarkClearFat512 22.3 18.0 -19.28%
BenchmarkCopyFat512 22.0 19.7 -10.45%
BenchmarkCopyFat1024 36.5 38.4 +5.21%
BenchmarkClearFat1024 35.1 35.0 -0.28%
TODO: use for stack frame zeroing
TODO: REP prefixes are still used for "reverse" copying when src/dst
regions overlap. Might be worth fixing.
LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews, r
https://golang.org/cl/81370046
The new channel and map runtime routines take pointers
to values, typically temporaries. Without help, the compiler
cannot tell when those temporaries stop being needed,
because it isn't sure what happened to the pointer.
Arrange to insert explicit VARKILL instructions for these
temporaries so that the liveness analysis can avoid seeing
them as "ambiguously live".
The change is made in order.c, which was already in charge of
introducing temporaries to preserve the order-of-evaluation
guarantees. Now its job has expanded to include introducing
temporaries as needed by runtime routines, and then also
inserting the VARKILL annotations for all these temporaries,
so that their lifetimes can be shortened.
In order to do its job for the map runtime routines, order.c arranges
that all map lookups or map assignments have the form:
x = m[k]
x, y = m[k]
m[k] = x
where x, y, and k are simple variables (often temporaries).
Likewise, receiving from a channel is now always:
x = <-c
In order to provide the map guarantee, order.c is responsible for
rewriting x op= y into x = x op y, so that m[k] += z becomes
t = m[k]
t2 = t + z
m[k] = t2
While here, fix a few bugs in order.c's traversal: it was failing to
walk into select and switch case bodies, so order of evaluation
guarantees were not preserved in those situations.
Added tests to test/reorder2.go.
Fixes#7671.
In gc/popt's temporary-merging optimization, allow merging
of temporaries with their address taken as long as the liveness
ranges do not intersect. (There is a good chance of that now
that we have VARKILL annotations to limit the liveness range.)
Explicitly killing temporaries cuts the number of ambiguously
live temporaries that must be zeroed in the godoc binary from
860 to 711, or -17%. There is more work to be done, but this
is a good checkpoint.
Update #7345
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/81940043
e.g., don't delete /dev/null. this fix inspired by gnu libiberty,
unlink-if-ordinary.c.
Fixes#7563
LGTM=iant
R=golang-codereviews, iant, 0intro
CC=golang-codereviews, r
https://golang.org/cl/76810045
chanrecv now expects a pointer to the data to be filled in.
mapiterinit expects a pointer to the hash iterator to be filled in.
In both cases, the temporary being pointed at changes from
dead to alive during the call. In order to make sure it is
preserved if a garbage collection happens after that transition
but before the call returns, the temp must be marked as live
during the entire call.
But if it is live during the entire call, it needs to be safe for
the garbage collector to scan at the beginning of the call,
before the new data has been filled in. Therefore, it must be
zeroed by the caller, before the call. Do that.
My previous attempt waited to mark it live until after the
call returned, but that's unsafe (see first paragraph);
undo that change in plive.c.
This makes powser2 pass again reliably.
I looked at every call to temp in the compiler.
The vast majority are followed immediately by an
initialization of temp, so those are fine.
The only ones that needed changing were the ones
where the next operation is to pass the address of
the temp to a function call, and there aren't too many.
Maps are exempted from this because mapaccess
returns a pointer to the data and lets the caller make
the copy.
Fixes many builds.
TBR=khr
CC=golang-codereviews
https://golang.org/cl/80700046
cgo represents all 0-sized and unsized types internally as [0]byte. This means that pointers to incomplete types would be interchangable, even if given a name by typedef.
Fixes#7409.
LGTM=iant
R=golang-codereviews, bradfitz, iant
CC=golang-codereviews
https://golang.org/cl/76450043
1. On entry to a function, only zero the ambiguously live stack variables.
Before, we were zeroing all stack variables containing pointers.
The zeroing is pretty inefficient right now (issue 7624), but there are also
too many stack variables detected as ambiguously live (issue 7345),
and that must be addressed before deciding how to improve the zeroing code.
(Changes in 5g/ggen.c, 6g/ggen.c, 8g/ggen.c, gc/pgen.c)
Fixes#7647.
2. Make the regopt word-based liveness analysis preserve the
whole-variable liveness property expected by the garbage collection
bitmap liveness analysis. That is, if the regopt liveness decides that
one word in a struct needs to be preserved, make sure it preserves
the entire struct. This is particularly important for multiword values
such as strings, slices, and interfaces, in which all the words need
to be present in order to understand the meaning.
(Changes in 5g/reg.c, 6g/reg.c, 8g/reg.c.)
Fixes#7591.
3. Make the regopt word-based liveness analysis treat a variable
as having its address taken - which makes it preserved across
all future calls - whenever n->addrtaken is set, for consistency
with the gc bitmap liveness analysis, even if there is no machine
instruction actually taking the address. In this case n->addrtaken
is incorrect (a nicer way to put it is overconservative), and ideally
there would be no such cases, but they can happen and the two
analyses need to agree.
(Changes in 5g/reg.c, 6g/reg.c, 8g/reg.c; test in bug484.go.)
Fixes crashes found by turning off "zero everything" in step 1.
4. Remove spurious VARDEF annotations. As the comment in
gc/pgen.c explains, the VARDEF must immediately precede
the initialization. It cannot be too early, and it cannot be too late.
In particular, if a function call sits between the VARDEF and the
actual machine instructions doing the initialization, the variable
will be treated as live during that function call even though it is
uninitialized, leading to problems.
(Changes in gc/gen.c; test in live.go.)
Fixes crashes found by turning off "zero everything" in step 1.
5. Do not treat loading the address of a wide value as a signal
that the value must be initialized. Instead depend on the existence
of a VARDEF or the first actual read/write of a word in the value.
If the load is in order to pass the address to a function that does
the actual initialization, treating the load as an implicit VARDEF
causes the same problems as described in step 4.
The alternative is to arrange to zero every such value before
passing it to the real initialization function, but this is a much
easier and more efficient change.
(Changes in gc/plive.c.)
Fixes crashes found by turning off "zero everything" in step 1.
6. Treat wide input parameters with their address taken as
initialized on entry to the function. Otherwise they look
"ambiguously live" and we will try to emit code to zero them.
(Changes in gc/plive.c.)
Fixes crashes found by turning off "zero everything" in step 1.
7. An array of length 0 has no pointers, even if the element type does.
Without this change, the zeroing code complains when asked to
clear a 0-length array.
(Changes in gc/reflect.c.)
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/80160044
Zeroing the outputs makes sure that during function calls
in those functions we do not let the garbage collector
treat uninitialized values as pointers.
The garbage collector may still see uninitialized values
if a preemption occurs during the function prologue,
before the zeroing has had a chance to run.
This reduces the number of 'bad pointer' messages when
that runtime check is enabled, but it doesn't fix all of them,
so the check is still disabled.
It will also avoid leaks, although I doubt any of these were
particularly serious.
LGTM=iant, khr
R=iant, khr
CC=golang-codereviews
https://golang.org/cl/80850044
If you compile a program that has cgo LDFLAGS directives, those are exported to an environment variable to be used by subsequent compiler tool invocations. The linking phase when using the gccgo toolchain did not consider the envvar CGO_LDFLAGS's linking directives resulting in undefined references when using cgo+gccgo.
Fixes#7573
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/80780043
GCC on OS X 10.6 doesn't support -Wuninitialized without -O.
Fixes#7492.
LGTM=iant
R=golang-codereviews, dave, iant
CC=golang-codereviews
https://golang.org/cl/72360045
Fixes#7627.
CL 61970044 changed the order in which .a files are passed to gccgo's link phase. However by reversing the order it caused gccgo to complain if both internal (liba.a) and external (liba_test.a) versions of a package were presented as the former would not contain all the necessary symbols, and the latter would duplicate symbols already defined.
This change ensures that all 'fake' targets remain at the top of the final link order which should be fine as a package compiled as an external test is a superset of its internal sibling.
Looking at how gcToolchain links tests I think this change now accurately mirrors those actions which present $WORK/_test before $WORK in the link order.
LGTM=iant
R=rsc, iant
CC=golang-codereviews, michael.hudson
https://golang.org/cl/80300043
Change two-bit stack map entries to encode:
0 = dead
1 = scalar
2 = pointer
3 = multiword
If multiword, the two-bit entry for the following word encodes:
0 = string
1 = slice
2 = iface
3 = eface
That way, during stack scanning we can check if a string
is zero length or a slice has zero capacity. We can avoid
following the contained pointer in those cases. It is safe
to do so because it can never be dereferenced, and it is
desirable to do so because it may cause false retention
of the following block in memory.
Slice feature turned off until issue 7564 is fixed.
Update #7549
LGTM=rsc
R=golang-codereviews, bradfitz, rsc
CC=golang-codereviews
https://golang.org/cl/76380043
Revision 3ae4607a43ff introduced CONVNOP layers
to fix type checking issues arising from comparisons.
The added complexity made 8g run out of registers
when compiling an equality function in go.net/ipv6.
A similar issue occurred in test/sizeof.go on
amd64p32 with 6g.
Fixes#7405.
LGTM=khr
R=rsc, dave, iant, khr
CC=golang-codereviews
https://golang.org/cl/78100044
Removes most uses of the REP prefix, which has a high startup cost.
LGTM=iant
R=golang-codereviews, iant, khr
CC=golang-codereviews
https://golang.org/cl/77920043
A too large float constant is an error.
A too small float constant is rounded to zero.
Fixes#7419
Update #6902
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/76730046
Old versions of DTrace (as those shipped in OS X and FreeBSD)
don't support unicode characters in symbol names. Replace '·'
to '.' to make DTrace happy.
Fixes#7493
LGTM=aram, rsc
R=aram, rsc, gobot, iant
CC=golang-codereviews
https://golang.org/cl/72280043
The lowering to runtime calls introduces hidden pointers to the
arguments of select clauses. When implicit conversions were
involved it could end up with incompatible pointers. Since the
pointed-to types have the same representation, we can introduce a
forced conversion.
Fixes#6847.
LGTM=rsc
R=rsc, iant, khr
CC=golang-codereviews
https://golang.org/cl/72380043
It was using a REP STOSQ but putting in CX the number of 32-bit
words to clear.
LGTM=dave
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/75240043
Under some circumstances, gccgoToolchain's ld can pass the path of
build outputs that have been deleted to the link command.
Fixes#7303.
LGTM=rsc
R=golang-codereviews, dave, michael.hudson, rsc
CC=golang-codereviews
https://golang.org/cl/61970044
The compilers expect to not be interrupted by floating
point exceptions. On Plan 9, every process starts with
interrupts enabled for invalid operation, stack overflow,
and divide by zero exceptions.
LGTM=rsc
R=rsc, 0intro
CC=golang-codereviews
https://golang.org/cl/72750043
Acid can't produce a stack trace without .frame symbols.
Of course, it can only unwind through linear stacks but
this is still better than nothing. (I wrote an acid func
to do the full unwind a long time ago but lost it and
haven't worked up the courage to write it again).
Note that these will only be present in the native symbol
table for Plan 9 binaries.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/72450045
debuglive >= 1 is not the condition under which we
start recording messages (we avoid printing for
init functions even if debuglive is set).
LGTM=bradfitz, iant
R=golang-codereviews, bradfitz
CC=golang-codereviews, iant, khr
https://golang.org/cl/74390043
This fixes the following amd64p32 issue:
pkg/time/format.go:724: internal compiler error: twobitwalktype1: invalid initial alignment, Time
caused by the pointer zone ending on a 32-bit-aligned boundary.
LGTM=rsc
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/72270046
Replaces CL 70000043.
Switch to the amd64p32 linker model if we are building under nacl/amd64p32.
No need to introduce linkarchinit() as 6a contains its own main() function.
LGTM=rsc
R=rsc, minux.ma
CC=golang-codereviews
https://golang.org/cl/72020043
Replaces CL 70000043.
Introduce linkarchinit() from cmd/ld.
For cmd/6g, switch to the amd64p32 linker model if we are building under nacl/amd64p32.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/71330045
This is a test case for CL 34680044.
Fixes#6333.
LGTM=bradfitz
R=golang-codereviews, bradfitz, minux.ma
CC=golang-codereviews
https://golang.org/cl/71230049
Replaces CL 70000043.
Introduce linkarchinit() from cmd/ld.
For cmd/6c, switch to the amd64p32 linker model if we are building under nacl/amd64p32.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/72010043
Tested GOARM=6 on Raspberry Pi, and I found only a few tests that
use sub-normal numbers fails. I have a patch to NetBSD kernel pending
that fixes this issue (NetBSD kernel doesn't allow us to disable the
Flush-to-Zero feature).
LGTM=jsing
R=golang-codereviews, jsing
CC=golang-codereviews
https://golang.org/cl/70730043
Essentialy for running tests without a working cmd/go.
While we're at it, also fix a typo.
LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/70640043
Recently NetBSD starts to enforce this, and refuses to execute
the program if n is larger than the sum of entry sizes.
Before:
$ readelf -n ../bin/go.old
Notes at offset 0x00000bd0 with length 0x00000019:
Owner Data size Description
NetBSD 0x00000004 NT_VERSION (version)
readelf: Warning: corrupt note found at offset 18 into core notes
readelf: Warning: type: 0, namesize: 00000000, descsize: 00000000
$ readelf -n ../bin/go
Notes at offset 0x00000bd0 with length 0x00000018:
Owner Data size Description
NetBSD 0x00000004 NT_VERSION (version)
LGTM=iant
R=iant
CC=golang-codereviews
https://golang.org/cl/70710043
Add CgoFiles to the covered files when building
with cover support.
LGTM=rsc
R=golang-codereviews, gobot, r, rsc
CC=golang-codereviews
https://golang.org/cl/34680044
Apparently, the Windows routines sometimes fail to generate output.
Copy the Unix stdio-based implementations instead.
Suggested by Pietro Gagliardi in CL 65280043 but that CL
seems to have been abandoned.
Fixes#7242.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/71550044
For non-closure functions, the context register is uninitialized
on entry and will not be used, but morestack saves it and then the
garbage collector treats it as live. This can be a source of memory
leaks if the context register points at otherwise dead memory.
Avoid this by introducing a parallel set of morestack functions
that clear the context register, and use those for the non-closure functions.
I hope this will help with some of the finalizer flakiness, but it probably won't.
Fixes#7244.
LGTM=dvyukov
R=khr, dvyukov
CC=golang-codereviews
https://golang.org/cl/71030044
warning: src/cmd/ld/pcln.c:184 more arguments than format INT
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/69870047
The pcln file number was being encoded incorrectly. The recorded delta was always against -1, not against the previous value.
Update #7369
This CL fixes the bad DWARF file numbers. It does not, however, fix the gdb continue-to-end bug.
LGTM=iant
R=rsc, minux.ma, iant
CC=golang-codereviews, graham
https://golang.org/cl/68960046
This CL replays the following one CL from the rsc-go13nacl repo.
This is the last replay CL: after this CL the main repo will have
everything the rsc-go13nacl repo did. Changes made to the main
repo after the rsc-go13nacl repo branched off probably mean that
NaCl doesn't actually work after this CL, but all the code is now moved
over and just needs to be redebugged.
---
cmd/6l, cmd/8l, cmd/ld: support for Native Client
See golang.org/s/go13nacl for design overview.
This CL is publicly visible but not CC'ed to golang-dev,
to avoid distracting from the preparation of the Go 1.2
release.
This CL and the others will be checked into my rsc-go13nacl
clone repo for now, and I will send CLs against the main
repo early in the Go 1.3 development.
R≡khr
https://golang.org/cl/15750044
---
LGTM=bradfitz, dave, iant
R=dave, bradfitz, iant
CC=golang-codereviews
https://golang.org/cl/69040044
The cached computed interface tables are indexed by the interface
types, not by the unnamed underlying interfaces
To preserve the invariants expected by interface comparison, an
itab generated for an interface type must not be used for a value
of a different interface type even if the representation is identical.
Fixes#7207.
LGTM=rsc
R=rsc, iant, khr
CC=golang-codereviews
https://golang.org/cl/69210044
From the original description in CL 15770043
The main change here is to consult $GOARCH.
In 6c, when GOOS=nacl, some of the more complex addressing modes must be disabled, and the BP and R15 registers must not be used.
See golang.org/s/go13nacl for design overview.
LGTM=rsc
R=golang-codereviews, gobot, rsc
CC=golang-codereviews
https://golang.org/cl/69020044
The gvardef function does nothing if n->class == PEXTERN, so
we don't need to test for that before calling it. This makes
the 6g/8g code more like the 5g code and clarifies that the
cases that do not test for n->class != PEXTERN are not buggy.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/68900044
maxstksize is superfluous and appears to be vestigial. 6g does not use it.
c >= 4 cannot occur; c = w % 4.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/68750043
These previously reviewed CLs are present in this CL.
---
changeset: 18445:436bb084caed
user: Russ Cox <rsc@golang.org>
date: Mon Nov 11 09:50:34 2013 -0500
description:
runtime: assembly and system calls for Native Client x86-64
See golang.org/s/go13nacl for design overview.
This CL is publicly visible but not CC'ed to golang-dev,
to avoid distracting from the preparation of the Go 1.2
release.
This CL and the others will be checked into my rsc-go13nacl
clone repo for now, and I will send CLs against the main
repo early in the Go 1.3 development.
R≡adg
https://golang.org/cl/15760044
---
changeset: 18448:90bd871b5994
user: Russ Cox <rsc@golang.org>
date: Mon Nov 11 09:51:36 2013 -0500
description:
runtime: amd64p32 and Native Client assembly bootstrap
See golang.org/s/go13nacl for design overview.
This CL is publicly visible but not CC'ed to golang-dev,
to avoid distracting from the preparation of the Go 1.2
release.
This CL and the others will be checked into my rsc-go13nacl
clone repo for now, and I will send CLs against the main
repo early in the Go 1.3 development.
R≡khr
https://golang.org/cl/15820043
---
changeset: 18449:b011c3dc687e
user: Russ Cox <rsc@golang.org>
date: Mon Nov 11 09:51:58 2013 -0500
description:
math: amd64p32 assembly routines
These routines only manipulate float64 values,
so the amd64 and amd64p32 can share assembly.
The large number of files is symptomatic of a problem
with package path: it is a Go package structured like a C library.
But that will need to wait for another day.
See golang.org/s/go13nacl for design overview.
This CL is publicly visible but not CC'ed to golang-dev,
to avoid distracting from the preparation of the Go 1.2
release.
This CL and the others will be checked into my rsc-go13nacl
clone repo for now, and I will send CLs against the main
repo early in the Go 1.3 development.
R≡bradfitz
https://golang.org/cl/15870043
---
changeset: 18450:43234f082eec
user: Russ Cox <rsc@golang.org>
date: Mon Nov 11 10:03:19 2013 -0500
description:
syscall: networking for Native Client
See golang.org/s/go13nacl for design overview.
This CL is publicly visible but not CC'ed to golang-dev,
to avoid distracting from the preparation of the Go 1.2
release.
This CL and the others will be checked into my rsc-go13nacl
clone repo for now, and I will send CLs against the main
repo early in the Go 1.3 development.
R≡rsc
https://golang.org/cl/15780043
---
changeset: 18451:9c8d1d890aaa
user: Russ Cox <rsc@golang.org>
date: Mon Nov 11 10:03:34 2013 -0500
description:
runtime: assembly and system calls for Native Client x86-32
See golang.org/s/go13nacl for design overview.
This CL is publicly visible but not CC'ed to golang-dev,
to avoid distracting from the preparation of the Go 1.2
release.
This CL and the others will be checked into my rsc-go13nacl
clone repo for now, and I will send CLs against the main
repo early in the Go 1.3 development.
R≡rsc
https://golang.org/cl/15800043
---
changeset: 18452:f90b1dd9228f
user: Russ Cox <rsc@golang.org>
date: Mon Nov 11 11:04:09 2013 -0500
description:
runtime: fix frame size for linux/amd64 runtime.raise
R≡rsc
https://golang.org/cl/24480043
---
changeset: 18445:436bb084caed
user: Russ Cox <rsc@golang.org>
date: Mon Nov 11 09:50:34 2013 -0500
description:
runtime: assembly and system calls for Native Client x86-64
See golang.org/s/go13nacl for design overview.
This CL is publicly visible but not CC'ed to golang-dev,
to avoid distracting from the preparation of the Go 1.2
release.
This CL and the others will be checked into my rsc-go13nacl
clone repo for now, and I will send CLs against the main
repo early in the Go 1.3 development.
R≡adg
https://golang.org/cl/15760044
---
changeset: 18455:53b06799a938
user: Russ Cox <rsc@golang.org>
date: Mon Nov 11 23:29:52 2013 -0500
description:
cmd/gc: add -nolocalimports flag
R≡dsymonds
https://golang.org/cl/24990043
---
changeset: 18456:24f64e1eaa8a
user: Russ Cox <rsc@golang.org>
date: Tue Nov 12 22:06:29 2013 -0500
description:
runtime: add comments for playback write
R≡adg
https://golang.org/cl/25190043
---
changeset: 18457:d1f615bbb6e4
user: Russ Cox <rsc@golang.org>
date: Wed Nov 13 17:03:52 2013 -0500
description:
runtime: write only to NaCl stdout, never to NaCl stderr
NaCl writes some other messages on standard error
that we would like to be able to squelch.
R≡adg
https://golang.org/cl/26240044
---
changeset: 18458:1f01be1a1dc2
tag: tip
user: Russ Cox <rsc@golang.org>
date: Wed Nov 13 19:45:16 2013 -0500
description:
runtime: remove apparent debugging dreg
Setting timens to 0 turns off fake time.
TBR≡adg
https://golang.org/cl/26400043
LGTM=bradfitz
R=dave, bradfitz
CC=golang-codereviews
https://golang.org/cl/68730043
The parser was assuming it would find <body> or </head>.
If the entire response is just <meta> tags, it finds EOF and
treats that as an error. It's not.
LGTM=bradfitz
R=bradfitz
CC=golang-codereviews
https://golang.org/cl/68520044
The new flag was added by CL 68150047 (part of the NaCl replay),
but the change, like the original, omitted documentation of the
new behavior.
LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/68580043
See golang.org/s/go13nacl for design overview.
This CL is the mostly mechanical changes from rsc's Go 1.2 based NaCl branch, specifically 39cb35750369 to 500771b477cf from https://code.google.com/r/rsc-go13nacl. This CL does not include working NaCl support, there are probably two or three more large merges to come.
CL 15750044 is not included as it involves more invasive changes to the linker which will need to be merged separately.
The exact change lists included are
15050047: syscall: support for Native Client
15360044: syscall: unzip implementation for Native Client
15370044: syscall: Native Client SRPC implementation
15400047: cmd/dist, cmd/go, go/build, test: support for Native Client
15410048: runtime: support for Native Client
15410049: syscall: file descriptor table for Native Client
15410050: syscall: in-memory file system for Native Client
15440048: all: update +build lines for Native Client port
15540045: cmd/6g, cmd/8g, cmd/gc: support for Native Client
15570045: os: support for Native Client
15680044: crypto/..., hash/crc32, reflect, sync/atomic: support for amd64p32
15690044: net: support for Native Client
15690048: runtime: support for fake time like on Go Playground
15690051: build: disable various tests on Native Client
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/68150047
Revision c0e0467635ec (cmd/gc: return canonical Node* from temp)
exposed original nodes of temporaries, allowing callers to mutate
their types.
In walkcompare a temporary could be typed as ideal because of
this. Additionnally, assignment of a comparison result to
a custom boolean type was broken.
Fixes#7366.
LGTM=rsc
R=rsc, iant, khr
CC=golang-codereviews
https://golang.org/cl/66930044
Fixes the output of go env so that variables can be set
more accurately when using Plan 9's rc shell. Specifically,
GOPATH may have multiple components and the current
representation is plain wrong. In practice, we probably
ought to change os. Getenv to produce the right result, but
that requires considerably more thought.
LGTM=rsc
R=golang-codereviews, gobot, rsc
CC=golang-codereviews
https://golang.org/cl/66600043
Package runtime's C functions written to be called from Go
started out written in C using carefully constructed argument
lists and the FLUSH macro to write a result back to memory.
For some functions, the appropriate parameter list ended up
being architecture-dependent due to differences in alignment,
so we added 'goc2c', which takes a .goc file containing Go func
declarations but C bodies, rewrites the Go func declaration to
equivalent C declarations for the target architecture, adds the
needed FLUSH statements, and writes out an equivalent C file.
That C file is compiled as part of package runtime.
Native Client's x86-64 support introduces the most complex
alignment rules yet, breaking many functions that could until
now be portably written in C. Using goc2c for those avoids the
breakage.
Separately, Keith's work on emitting stack information from
the C compiler would require the hand-written functions
to add #pragmas specifying how many arguments are result
parameters. Using goc2c for those avoids maintaining #pragmas.
For both reasons, use goc2c for as many Go-called C functions
as possible.
This CL is a replay of the bulk of CL 15400047 and CL 15790043,
both of which were reviewed as part of the NaCl port and are
checked in to the NaCl branch. This CL is part of bringing the
NaCl code into the main tree.
No new code here, just reformatting and occasional movement
into .h files.
LGTM=r
R=dave, alex.brainman, r
CC=golang-codereviews
https://golang.org/cl/65220044
Match used len(ar.files) == 0 to mean "match everything"
but it also deleted matched things from the list, so once you
had matched everything you asked for, match returned true
for whatever was left in the archive too.
Concretely, if you have an archive containing f1, f2, then
pack t foo.a f1
would match f1 and then, because len(ar.files) == 0 after
deleting f1 from the match list, also match f2.
Avoid the problem by recording explicitly whether match
matches everything.
LGTM=r, dsymonds
R=r, dsymonds
CC=golang-codereviews
https://golang.org/cl/65630046
Get more information to help understand build failure on Plan 9.
Also Windows.
(TestHello is failing because GOCHAR does not appear in output.
What does?)
Update #7362
LGTM=bradfitz
R=rsc, bradfitz
CC=golang-codereviews
https://golang.org/cl/66070044
[Repeat of CL 64100044, after 32-bit fix in CL 66170043.]
Precisestack makes stack collection completely precise,
in the sense that there are no "used and not set" errors
in the collection of stack frames, no times where the collector
reads a pointer from a stack word that has not actually been
initialized with a pointer (possibly a nil pointer) in that function.
The most important part is interfaces: precisestack means
that if reading an interface value, the interface value is guaranteed
to be initialized, meaning that the type word can be relied
upon to be either nil or a valid interface type word describing
the data word.
This requires additional zeroing of certain values on the stack
on entry, which right now costs about 5% overall execution
time in all.bash. That cost will come down before Go 1.3
(issue 7345).
There are at least two known garbage collector bugs right now,
issues 7343 and 7344. The first happens even without precisestack.
The second I have only seen with precisestack, but that does not
mean that precisestack is what causes it. In fact it is very difficult
to explain by what precisestack does directly. Precisestack may
be exacerbating an existing problem. Both of those issues are
marked for Go 1.3 as well.
The reasons for enabling precisestack now are to give it more
time to soak and because the copying stack work depends on it.
LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/65820044
The code here is being restored after its deletion in CL 14430048.
I restored the copy in cmd/6g in CL 56430043 but neglected the
other two.
This is the reason that enabling precisestack only worked on amd64.
LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/66170043
When Go 1.3 is released, this will keep existing
Go 1.2 build scripts that use 'go tool pack grc' working.
For efficiency, such scripts should be changed to
use 6g -pack instead, but keeping the old behavior
available enables a more graceful transition.
LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/66130043
There are probably more of these, but bound and len are 64 bits so use %lld
in message about array index out of bounds.
Fixes the 386 build.
LGTM=bradfitz, rsc
R=rsc, bradfitz
CC=golang-codereviews, rickarnoldjr
https://golang.org/cl/66110043
We never updated libmach for the new object file format,
so it the existing 'go tool addr2line' is broken.
Reimplement in Go to fix.
LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/66020043
The error message was previously off by one in all cases.
Fixes#7150.
LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/65850043
Update #6853
For an ephemeral binary - one created, run, and then deleted -
there is no need to write dwarf debug information, since the
binary will not be used with gdb. In this case, instruct the linker
not to spend time and disk space generating the debug information
by passing the -w flag to the linker.
Omitting dwarf information reduces the size of most binaries by 25%.
We may be more aggressive about this in the future.
LGTM=bradfitz, r
R=r, bradfitz
CC=golang-codereviews
https://golang.org/cl/65890043
Update #6853
Every function now has a gcargs and gclocals symbol
holding associated garbage collection information.
Put them all in the same meta-symbol as the go.func data
and then drop individual entries from symbol table.
Removing gcargs and gclocals reduces the size of a
typical binary by 10%.
LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/65870044
