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cmd/vet: false positive for uint128 ([2]uint64) #46843

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zhangyunhao116 opened this issue Jun 21, 2021 · 4 comments
Closed

cmd/vet: false positive for uint128 ([2]uint64) #46843

zhangyunhao116 opened this issue Jun 21, 2021 · 4 comments
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FrozenDueToAge NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one.

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@zhangyunhao116
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zhangyunhao116 commented Jun 21, 2021 •
edited

What version of Go are you using (go version)?

$ go version
go version go1.16.5 linux/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output
$ go env
GO111MODULE="auto"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/zyh/.cache/go-build"
GOENV="/home/zyh/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/zyh/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/zyh/go"
GOPRIVATE=""
GOPROXY="https://goproxy.cn,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.16.5"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/zyh/GitHub/lscqtest/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build2984921841=/tmp/go-build -gno-record-gcc-switches"

What did you do?

go vet these files

asm.go Content 
// +build amd64,!gccgo,!appengine

package lscq


import "unsafe"


type uint128 [2]uint64


func compareAndSwapUint128(addr *uint128, old, new uint128) (swapped bool)

asm_amd64.s Content 
// +build amd64,!gccgo,!appengine

#include "textflag.h"


TEXT ·compareAndSwapUint128(SB),NOSPLIT,$0

MOVQ addr+0(FP), R8

MOVQ old+8(FP), AX

MOVQ old+16(FP), DX

MOVQ new+24(FP), BX

MOVQ new+32(FP), CX

LOCK

CMPXCHG16B (R8)

SETEQ swapped+40(FP)

RET

What did you expect to see?

Nothing will happen.

What did you see instead?

./asm_amd64.s:7:1: [amd64] compareAndSwapUint128: invalid MOVQ of old+8(FP); github.com/zhangyunhao116/lscqtest.uint128 is 16-byte value
./asm_amd64.s:8:1: [amd64] compareAndSwapUint128: invalid offset old+16(FP); expected old+8(FP)
./asm_amd64.s:9:1: [amd64] compareAndSwapUint128: invalid MOVQ of new+24(FP); github.com/zhangyunhao116/lscqtest.uint128 is 16-byte value
./asm_amd64.s:10:1: [amd64] compareAndSwapUint128: invalid offset new+32(FP); expected new+24(FP)
./asm_amd64.s:24:1: [amd64] loadUint128: invalid MOVQ of val+8(FP); github.com/zhangyunhao116/lscqtest.uint128 is 16-byte value
./asm_amd64.s:25:1: [amd64] loadUint128: invalid offset val+16(FP); expected val+8(FP)
@zhangyunhao116
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Some hints:
These errors come from
https://github.com/golang/tools/blob/master/go/analysis/passes/asmdecl/asmdecl.go#L782
https://github.com/golang/tools/blob/master/go/analysis/passes/asmdecl/asmdecl.go#L800

Looks like go vet should allow a single instruction to load each part of an array?

@seankhliao
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cc @matloob

@seankhliao seankhliao added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Jun 21, 2021
@josharian
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Try e.g.

MOVQ new_0+24(FP), BX
MOVQ new_1+32(FP), CX

That is, use underscores to refer to components of a composite type.

@zhangyunhao116
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@josharian It works, thanks a lot!

Try e.g.

MOVQ new_0+24(FP), BX
MOVQ new_1+32(FP), CX

That is, use underscores to refer to components of a composite type.

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