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mhr3 opened this issue Oct 5, 2024 · 5 comments
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x/arch/x86: objdump cannot decode AVX instructions #69792

mhr3 opened this issue Oct 5, 2024 · 5 comments
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@mhr3
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mhr3 commented Oct 5, 2024

Go version

go version go1.23.1 darwin/arm64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='arm64'
GOBIN=''
GOCACHE='/Users/mhr3/Library/Caches/go-build'
GOENV='/Users/mhr3/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='arm64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMODCACHE='/Users/mhr3/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='darwin'
GOPATH='/Users/mhr3/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/opt/homebrew/Cellar/go/1.23.1/libexec'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='local'
GOTOOLDIR='/opt/homebrew/Cellar/go/1.23.1/libexec/pkg/tool/darwin_arm64'
GOVCS=''
GOVERSION='go1.23.1'
GODEBUG=''
GOTELEMETRY='local'
GOTELEMETRYDIR='/Users/mhr3/Library/Application Support/go/telemetry'
GCCGO='gccgo'
GOARM64='v8.0'
AR='ar'
CC='cc'
CXX='c++'
CGO_ENABLED='1'
GOMOD='/tmp/go-bin/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/k6/z2zpftk571d89c88yzh8b65c0000gn/T/go-build1267667530=/tmp/go-build -gno-record-gcc-switches -fno-common'

What did you do?

Running go tool objdump on a go binary cannot decode functions containing AVX instructions, for example when running objdump on a simple go binary built from this source code:

package main

import (
	"strings"
)

func main() {
	_ = strings.Contains("foo", "oo")
}

What did you see happen?

Building a amd64 binary using the above source code and running go tool objdump -s indexbytebody ./main outputs disassembled version of internal/bytealg/indexbyte_amd64.s, which contains (snip):

TEXT _indexbytebody(SB) /opt/homebrew/Cellar/go/1.23.1/libexec/src/internal/bytealg/indexbyte_amd64.s
  indexbyte_amd64.s:32	0x1003400		66480f6ec0		MOVQ AX, X0
  indexbyte_amd64.s:33	0x1003405		660f60c0		PUNPCKLBW X0, X0
  indexbyte_amd64.s:34	0x1003409		660f60c0		PUNPCKLBW X0, X0
...
  indexbyte_amd64.s:122	0x10034b6		803dc646180001		CMPB internal/cpu.X86+67(SB), $0x1
  indexbyte_amd64.s:123	0x10034bd		0f8562ffffff		JNE 0x1003425
  indexbyte_amd64.s:125	0x10034c3		66480f6ec0		MOVQ AX, X0
  indexbyte_amd64.s:126	0x10034c8		4c8d5c1ee0		LEAQ -0x20(SI)(BX*1), R11
  indexbyte_amd64.s:127	0x10034cd		c4e27d78c8		JS 0x100349a
  indexbyte_amd64.s:127	0x10034d2		660f1f840000000000	NOPW 0(AX)(AX*1)
  indexbyte_amd64.s:127	0x10034db		0f1f440000		NOPL 0(AX)(AX*1)
  indexbyte_amd64.s:131	0x10034e0		c5fe6f17		VMOVDQU 0(DI), X2
  indexbyte_amd64.s:132	0x10034e4		c5ed74d9		JE 0x10034c1
  indexbyte_amd64.s:133	0x10034e8		c4			?
  indexbyte_amd64.s:133	0x10034e9		e27d			LOOP 0x1003568
  indexbyte_amd64.s:133	0x10034eb		17			?
  indexbyte_amd64.s:133	0x10034ec		db			?

even though the source code contains:

go/src/internal/bytealg/indexbyte_amd64.s

Lines 121 to 133 in 2f50798

#ifndef hasAVX2
CMPB internal∕cpu·X86+const_offsetX86HasAVX2(SB), $1
JNE sse
#endif
MOVD AX, X0
LEAQ -32(SI)(BX*1), R11
VPBROADCASTB X0, Y1
PCALIGN $32
avx2_loop:
VMOVDQU (DI), Y2
VPCMPEQB Y1, Y2, Y3
VPTEST Y3, Y3

What did you expect to see?

The disassembled code should match the source code
@gopherbot gopherbot added this to the Unreleased milestone Oct 5, 2024
@gabyhelp
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gabyhelp commented Oct 5, 2024

Related Issues and Documentation

(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)

@mhr3 mhr3 mentioned this issue Oct 5, 2024
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@gopherbot
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Change https://go.dev/cl/618036 mentions this issue: x86: allow decoding of AVX instructions

@mhr3
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mhr3 commented Oct 5, 2024

Output with the linked PR:

  indexbyte_amd64.s:122	0x10034b6		803dc646180001		CMPB internal/cpu.X86+67(SB), $0x1
  indexbyte_amd64.s:123	0x10034bd		0f8562ffffff		JNE 0x1003425
  indexbyte_amd64.s:125	0x10034c3		66480f6ec0		MOVQ AX, X0
  indexbyte_amd64.s:126	0x10034c8		4c8d5c1ee0		LEAQ -0x20(SI)(BX*1), R11
  indexbyte_amd64.s:127	0x10034cd		c4e27d78c8		VPBROADCASTB X0, Y1
  indexbyte_amd64.s:127	0x10034d2		660f1f840000000000	NOPW 0(AX)(AX*1)
  indexbyte_amd64.s:127	0x10034db		0f1f440000		NOPL 0(AX)(AX*1)
  indexbyte_amd64.s:131	0x10034e0		c5fe6f17		VMOVDQU 0(DI), Y2
  indexbyte_amd64.s:132	0x10034e4		c5ed74d9		VPCMPEQB Y1, Y2, Y3
  indexbyte_amd64.s:133	0x10034e8		c4e27d17db		VPTEST Y3, Y3

@cherrymui
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Perhaps this is a duplicate of #47307 ?

@cherrymui
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This is similar to #47307. Closing as a dup. Thanks.

@cherrymui cherrymui closed this as not planned Won't fix, can't repro, duplicate, stale Oct 8, 2024
@gabyhelp gabyhelp mentioned this issue Mar 19, 2025
Closed
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