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reflect: method ABI and value ABI do not align #46696

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reusee opened this issue Jun 11, 2021 · 5 comments
Closed

reflect: method ABI and value ABI do not align #46696

reusee opened this issue Jun 11, 2021 · 5 comments
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@reusee
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@reusee reusee commented Jun 11, 2021

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

$ go version
go version go1.17beta1 windows/amd64

Does this issue reproduce with the latest release?

No

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

go env Output
$ go env
set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=C:\Users\reus\AppData\Local\go-build
set GOENV=C:\Users\reus\AppData\Roaming\go\env
set GOEXE=.exe
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMODCACHE=C:\Users\reus\go\pkg\mod
set GONOPROXY=github.com/reusee/*
set GONOSUMDB=github.com/reusee/*
set GOOS=windows
set GOPATH=C:\Users\reus\go
set GOPRIVATE=github.com/reusee/*
set GOPROXY=https://goproxy.cn,direct
set GOROOT=C:\Users\reus\sdk\go1.17beta1
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLDIR=C:\Users\reus\sdk\go1.17beta1\pkg\tool\windows_amd64
set GOVCS=
set GOVERSION=go1.17beta1
set GCCGO=gccgo
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=NUL
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=C:\Users\reus\AppData\Local\Temp\go-build1901699100=/tmp/go-build -gno-record-gcc-switches
GOROOT/bin/go version: go version go1.17beta1 windows/amd64
GOROOT/bin/go tool compile -V: compile version go1.17beta1

What did you do?

run


package main

import (
        "reflect"
)

type Foo struct{}

func (_ Foo) Foo(
        _ Bar,
        _ Bar,
        _ Baz,
        _ Baz,
        _ Baz,
        _ Bar,
        _ Qux,
) {
}

type Bar interface{}

type Baz func()

type Qux int

func main() {
        f := reflect.ValueOf(Foo{}).MethodByName("Foo").Interface()
        reflect.ValueOf(f).Call([]reflect.Value{
                reflect.ValueOf(Bar(42)),
                reflect.ValueOf(Bar(42)),
                reflect.ValueOf(Baz(nil)),
                reflect.ValueOf(Baz(nil)),
                reflect.ValueOf(Baz(nil)),
                reflect.ValueOf(Bar(42)),
                reflect.ValueOf(Qux(0)),
        })
}

What did you expect to see?

No panic

What did you see instead?

panic: method ABI and value ABI do not align                                                                                                                                                                                                                              goroutine 1 [running]:
reflect.callMethod(0xc000060040, 0xc00007d640, 0xc00007d518, 0xc00007d520)
        C:/Users/reus/sdk/go1.17beta1/src/reflect/value.go:969 +0x894
reflect.Value.call({0x6b18e0, 0xc000060040, 0x48}, {0x6bd1ee, 0x4}, {0xc00007dec8, 0x7, 0x6b18e0})
        C:/Users/reus/sdk/go1.17beta1/src/reflect/value.go:543 +0x814
reflect.Value.Call({0x6b18e0, 0xc000060040, 0x60}, {0xc00007dec8, 0x7, 0x7})
        C:/Users/reus/sdk/go1.17beta1/src/reflect/value.go:339 +0xc5
main.main()
        C:/Users/reus/a.go:30 +0x885
exit status 2
@ianlancetaylor
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@ianlancetaylor ianlancetaylor commented Jun 11, 2021

This panics in 1.17 but runs without error in earlier releases, so marking as a release blocker.

CC @mknyszek

@mknyszek
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@mknyszek mknyszek commented Jun 11, 2021

Thanks for the small reproducer. Looking into it.

@mknyszek
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@mknyszek mknyszek commented Jun 11, 2021

Slightly smaller reproducer:

package main

import (
	"fmt"
	"reflect"
)

type Foo struct{}

func (_ Foo) Foo(
	_ Bar,
	_ Bar,
	_ Baz,
	_ Baz,
	_ Baz,
	_ Bar,
	z Qux,
) int {
	return int(z)
}

type Bar interface{}

type Baz func()

type Qux int

func main() {
	f := reflect.ValueOf(Foo{}).MethodByName("Foo").Interface().(func(Bar, Bar, Baz, Baz, Baz, Bar, Qux) int)
	fmt.Println(f(Bar(42), Bar(42), Baz(nil), Baz(nil), Baz(nil), Bar(42), Qux(0)))
}

The failure is in the method value call, not the latter reflect call.

@mknyszek
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@mknyszek mknyszek commented Jun 11, 2021

I see the problem. In the "value" ABI the Qux-typed argument is stack-allocated, but in the "method" ABI, the argument before it (which is 16 bytes together) ends up on the stack, leaving a register free for the Qux-typed argument. callMethod erroneously assumes that this case can't happen.

Fix incoming.

@gopherbot
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@gopherbot gopherbot commented Jun 11, 2021

Change https://golang.org/cl/327089 mentions this issue: reflect: handle stack-to-register translation in callMethod

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