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cmd/cgo: use gcc_struct attribute for packed structs to work around GCC PR52991.

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Fixes #5603.

R=iant, dave
CC=gobot, golang-dev
https://golang.org/cl/9895043
This commit is contained in:
Shenghou Ma 2013-06-09 22:06:29 +08:00
parent e880ab112e
commit 949228a322
4 changed files with 41 additions and 2 deletions
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1
misc/cgo/test/cgo_test.go
View File

@ -41,5 +41,6 @@ func Test5227(t *testing.T) { test5227(t) }
func TestCflags(t *testing.T) { testCflags(t) }
func Test5337(t *testing.T) { test5337(t) }
func Test5548(t *testing.T) { test5548(t) }
func Test5603(t *testing.T) { test5603(t) }
func BenchmarkCgoCall(b *testing.B) { benchCgoCall(b) }

32
misc/cgo/test/issue5603.go Normal file
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@ -0,0 +1,32 @@
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package cgotest
/*
const long long issue5603exp = 0x12345678;
long long issue5603foo0() { return issue5603exp; }
long long issue5603foo1(void *p) { return issue5603exp; }
long long issue5603foo2(void *p, void *q) { return issue5603exp; }
long long issue5603foo3(void *p, void *q, void *r) { return issue5603exp; }
long long issue5603foo4(void *p, void *q, void *r, void *s) { return issue5603exp; }
*/
import "C"
import "testing"
func test5603(t *testing.T) {
var x [5]int64
exp := int64(C.issue5603exp)
x[0] = int64(C.issue5603foo0())
x[1] = int64(C.issue5603foo1(nil))
x[2] = int64(C.issue5603foo2(nil, nil))
x[3] = int64(C.issue5603foo3(nil, nil, nil))
x[4] = int64(C.issue5603foo4(nil, nil, nil, nil))
for i, v := range x {
if v != exp {
t.Errorf("issue5603foo%d() returns %v, expected %v", i, v, exp)
}
}
}

2
src/cmd/cgo/doc.go
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@ -310,7 +310,7 @@ file compiled by gcc, the file x.cgo2.c:
char* p0;
int r;
char __pad12[4];
} __attribute__((__packed__)) *a = v;
} __attribute__((__packed__, __gcc_struct__)) *a = v;
a->r = puts((void*)a->p0);
}

8
src/cmd/cgo/out.go
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@ -485,7 +485,13 @@ func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
// Use packed attribute to force no padding in this struct in case
// gcc has different packing requirements. For example,
// on 386 Windows, gcc wants to 8-align int64s, but 8c does not.
fmt.Fprintf(fgcc, "\t%s __attribute__((__packed__)) *a = v;\n", ctype)
// Use __gcc_struct__ to work around http://gcc.gnu.org/PR52991 on x86,
// and http://golang.org/issue/5603.
extraAttr := ""
if goarch == "amd64" || goarch == "386" {
extraAttr = ", __gcc_struct__"
}
fmt.Fprintf(fgcc, "\t%s __attribute__((__packed__%v)) *a = v;\n", ctype, extraAttr)
fmt.Fprintf(fgcc, "\t")
if t := n.FuncType.Result; t != nil {
fmt.Fprintf(fgcc, "a->r = ")