This commit adds a new option to the x86 assembler. If the
GOAMD64 environment variable is set to alignedjumps (the
default) and we're doing a 64 bit build, the assembler will
make sure that neither stand alone nor macro-fused jumps will
end on or cross 32 byte boundaries. To achieve this, functions
are aligned on 32 byte boundaries, rather than 16 bytes, and
jump instructions are padded to ensure that they do not
cross or end on 32 byte boundaries. Jumps are padded
by adding a NOP instruction of the appropriate length before
the jump.
The commit is likely to result in larger binary sizes when
GOAMD64=alignedjumps. On the binaries tested so far, an
increase of between 1.4% and 1.5% has been observed.
Updates #35881
Co-authored-by: David Chase <drchase@google.com>
Change-Id: Ief0722300bc3f987098e4fd92b22b14ad6281d91
Reviewed-on: https://go-review.googlesource.com/c/go/+/219357
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
I took some of the infrastructure from Austin's lock logging CR
https://go-review.googlesource.com/c/go/+/192704 (with deadlock
detection from the logs), and developed a setup to give static lock
ranking for runtime locks.
Static lock ranking establishes a documented total ordering among locks,
and then reports an error if the total order is violated. This can
happen if a deadlock happens (by acquiring a sequence of locks in
different orders), or if just one side of a possible deadlock happens.
Lock ordering deadlocks cannot happen as long as the lock ordering is
followed.
Along the way, I found a deadlock involving the new timer code, which Ian fixed
via https://go-review.googlesource.com/c/go/+/207348, as well as two other
potential deadlocks.
See the constants at the top of runtime/lockrank.go to show the static
lock ranking that I ended up with, along with some comments. This is
great documentation of the current intended lock ordering when acquiring
multiple locks in the runtime.
I also added an array lockPartialOrder[] which shows and enforces the
current partial ordering among locks (which is embedded within the total
ordering). This is more specific about the dependencies among locks.
I don't try to check the ranking within a lock class with multiple locks
that can be acquired at the same time (i.e. check the ranking when
multiple hchan locks are acquired).
Currently, I am doing a lockInit() call to set the lock rank of most
locks. Any lock that is not otherwise initialized is assumed to be a
leaf lock (a very high rank lock), so that eliminates the need to do
anything for a bunch of locks (including all architecture-dependent
locks). For two locks, root.lock and notifyList.lock (only in the
runtime/sema.go file), it is not as easy to do lock initialization, so
instead, I am passing the lock rank with the lock calls.
For Windows compilation, I needed to increase the StackGuard size from
896 to 928 because of the new lock-rank checking functions.
Checking of the static lock ranking is enabled by setting
GOEXPERIMENT=staticlockranking before doing a run.
To make sure that the static lock ranking code has no overhead in memory
or CPU when not enabled by GOEXPERIMENT, I changed 'go build/install' so
that it defines a build tag (with the same name) whenever any experiment
has been baked into the toolchain (by checking Expstring()). This allows
me to avoid increasing the size of the 'mutex' type when static lock
ranking is not enabled.
Fixes#38029
Change-Id: I154217ff307c47051f8dae9c2a03b53081acd83a
Reviewed-on: https://go-review.googlesource.com/c/go/+/207619
Reviewed-by: Dan Scales <danscales@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This is part two if the nacl removal. Part 1 was CL 199499.
This CL removes amd64p32 support, which might be useful in the future
if we implement the x32 ABI. It also removes the nacl bits in the
toolchain, and some remaining nacl bits.
Updates #30439
Change-Id: I2475d5bb066d1b474e00e40d95b520e7c2e286e1
Reviewed-on: https://go-review.googlesource.com/c/go/+/200077
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Setting environment variables for go command configuration
is too difficult and system-specific. This CL adds go env -w,
to change the default settings more easily, in a portable way.
It also adds go env -u, to unset those changes.
See https://golang.org/design/30411-env for details.
Fixes#30411.
Change-Id: I36e83f55b666459f8f7f482432a4a6ee015da71d
Reviewed-on: https://go-review.googlesource.com/c/go/+/171137
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Currently the offset values of ELF relocations and Macho relocations
are 256 and 512 respectively, which means that the space reserved for
ELF relocations is only 256. But AARCH64 has more than 256 ELF relocation
types, in fact the maximum AARCH64 ELF relocation type recorded in file
src/debug/elf/elf.go is 1032 currently. So this CL increases the offset
of Macho relocations to 2048 to leave enough space for AARCH64 ELF
relocations.
Change-Id: I784ac38aeb3e102ac7825f6d621086849c8d3146
Reviewed-on: https://go-review.googlesource.com/c/go/+/172497
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This change adds the environment variable GOWASM, which is a comma
separated list of experimental WebAssembly features that the compiled
WebAssembly binary is allowed to use. The default is to use no
experimental features. Initially there are no features avaiable.
More information about feature proposals can be found at
https://github.com/WebAssembly/proposals
Change-Id: I4c8dc534c99ecff8bb075dded0186ca8f8decaef
Reviewed-on: https://go-review.googlesource.com/c/go/+/168881
Run-TryBot: Richard Musiol <neelance@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@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>
Add an environment variable to make.bash to allow setting the default
dynamic linker/loader. This fixes alpine builds to use
/lib/ld-musl-x86_64.so.1:
$ readelf -l ../bin/go | grep 'interpreter:' | sed -e 's/^.*interpreter: \(.*\)[]]/\1/'
/lib/ld-musl-x86_64.so.1
Also re-enable the internal linker tests that were previously disabled
for alpine (CL 41759, CL 41678).
Fixes#18243
Updates #19938
This resurrects CL 50070 authored by Jessie Frazelle.
Change-Id: I132b5282045a3d60c8568e3b002a7f075eac2d93
Reviewed-on: https://go-review.googlesource.com/c/163977
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This experiment is less effective and less needed since the
introduction of stack objects.
We can't clobber stack objects because we don't know statically
whether they are live or not.
We don't really need this experiment that much any more, as it was
primarily used to test the complicated ambiguously-live logic in the
liveness analysis, which has been removed in favor of stack objects.
It is also ~infeasible to maintain once we have safepoints everywhere.
Fixes#27326
Change-Id: I3bdde480b93dd508d048703055d4586b496176af
Reviewed-on: https://go-review.googlesource.com/c/151317
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Enabling GODEBUGCPU without the need to set GOEXPERIMENT=debugcpu enables
trybots and builders to run tests for GODEBUGCPU features in upcoming CLs
that will implement the new syntax and features for non-experimental
GODEBUGCPU support from proposal golang.org/issue/27218.
Updates #27218
Change-Id: Icc69e51e736711a86b02b46bd441ffc28423beba
Reviewed-on: https://go-review.googlesource.com/c/141817
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Needs the go compiler to be build with GOEXPERIMENT=debugcpu to be active.
The GODEBUGCPU environment variable can be used to disable usage of
specific processor features in the Go standard library.
This is useful for testing and benchmarking different code paths that
are guarded by internal/cpu variable checks.
Use of processor features can not be enabled through GODEBUGCPU.
To disable usage of AVX and SSE41 cpu features on GOARCH amd64 use:
GODEBUGCPU=avx=0,sse41=0
The special "all" option can be used to disable all options:
GODEBUGCPU=all=0
Updates #12805
Updates #15403
Change-Id: I699c2e6f74d98472b6fb4b1e5ffbf29b15697aab
Reviewed-on: https://go-review.googlesource.com/91737
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
mips64 softfloat support is based on mips implementation and introduces
new enviroment variable GOMIPS64.
GOMIPS64 is a GOARCH=mips64{,le} specific option, for a choice between
hard-float and soft-float. Valid values are 'hardfloat' (default) and
'softfloat'. It is passed to the assembler as
'GOMIPS64_{hardfloat,softfloat}'.
Change-Id: I7f73078627f7cb37c588a38fb5c997fe09c56134
Reviewed-on: https://go-review.googlesource.com/108475
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Suppose you build the Go toolchain in directory A,
move the whole thing to directory B, and then use
it from B to build a new program hello.exe, and then
run hello.exe, and hello.exe crashes with a stack
trace into the standard library.
Long ago, you'd have seen hello.exe print file names
in the A directory tree, even though the files had moved
to the B directory tree. About two years ago we changed
the compiler to write down these files with the name
"$GOROOT" (that literal string) instead of A, so that the
final link from B could replace "$GOROOT" with B,
so that hello.exe's crash would show the correct source
file paths in the stack trace. (golang.org/cl/18200)
Now suppose that you do the same thing but hello.exe
doesn't crash: it prints fmt.Println(runtime.GOROOT()).
And you run hello.exe after clearing $GOROOT from the
environment.
Long ago, you'd have seen hello.exe print A instead of B.
Before this CL, you'd still see hello.exe print A instead of B.
This case is the one instance where a moved toolchain
still divulges its origin. Not anymore. After this CL, hello.exe
will print B, because the linker sets runtime/internal/sys.DefaultGoroot
with the effective GOROOT from link time.
This makes the default result of runtime.GOROOT once again
match the file names recorded in the binary, after two years
of divergence.
With that cleared up, we can reintroduce GOROOT into the
link action ID and also reenable TestExecutableGOROOT/RelocatedExe.
When $GOROOT_FINAL is set during link, it is used
in preference to $GOROOT, as always, but it was easier
to explain the behavior above without introducing that
complication.
Fixes#22155.
Fixes#20284.
Fixes#22475.
Change-Id: Ifdaeb77fd4678fdb337cf59ee25b2cd873ec1016
Reviewed-on: https://go-review.googlesource.com/86835
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
GOMIPS is a GOARCH=mips{,le} specific option, for a choice between
hard-float and soft-float. Valid values are 'hardfloat' (default) and
'softfloat'. It is passed to the assembler as
'GOMIPS_{hardfloat,softfloat}'.
Note: GOMIPS will later also be used for a choice of MIPS instruction
set (mips32/mips32r2).
Updates #18162
Change-Id: I35417db8625695f09d6ccc3042431dd2eaa756a6
Reviewed-on: https://go-review.googlesource.com/37954
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Framepointer is the default now. Only print an X: list
if the settings are _not_ the default.
Before:
$ go tool compile -V
compile version devel +a5f30d9508 Sun Jul 16 14:43:48 2017 -0400 X:framepointer
$ go1.8 tool compile -V
compile version go1.8 X:framepointer
$
After:
$ go tool compile -V
compile version devel +a5f30d9508 Sun Jul 16 14:43:48 2017 -0400
$ go1.9 tool compile -V # imagined
compile version go1.9
$
Perpetuates #18317.
Change-Id: I981ba5c62be32e650a166fc9740703122595639b
Reviewed-on: https://go-review.googlesource.com/49252
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
The experiment "clobberdead" clobbers all pointer fields that the
compiler thinks are dead, just before and after every safepoint.
Useful for debugging the generation of live pointer bitmaps.
Helped find the following issues:
Update #15936
Update #16026
Update #16095
Update #18860
Change-Id: Id1d12f86845e3d93bae903d968b1eac61fc461f9
Reviewed-on: https://go-review.googlesource.com/23924
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Now only cmd/asm and cmd/compile depend on cmd/internal/obj. Changing
the assembler backends no longer requires reinstalling cmd/link or
cmd/addr2line.
There's also now one canonical definition of the object file format in
cmd/internal/objabi/doc.go, with a warning to update all three
implementations.
objabi is still something of a grab bag of unrelated code (e.g., flag
and environment variable handling probably belong in a separate "tool"
package), but this is still progress.
Fixes#15165.
Fixes#20026.
Change-Id: Ic4b92fac7d0d35438e0d20c9579aad4085c5534c
Reviewed-on: https://go-review.googlesource.com/40972
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
