void callGoStackCheck(void);
void callPanic(void);
void callCgoAllocate(void);
+int callGoReturnVal(void);
+int returnAfterGrow(void);
+int returnAfterGrowFromGo(void);
*/
import "C"
C.callCgoAllocate() // crashes or exits on failure
}
+// Test that C code can return a value if it calls a Go function that
+// causes a stack copy.
+func testReturnAfterGrow(t *testing.T) {
+ // Use a new goroutine so that we get a small stack.
+ c := make(chan int)
+ go func() {
+ c <- int(C.returnAfterGrow())
+ }()
+ if got, want := <-c, 123456; got != want {
+ t.Errorf("got %d want %d", got, want)
+ }
+}
+
+// Test that we can return a value from Go->C->Go if the Go code
+// causes a stack copy.
+func testReturnAfterGrowFromGo(t *testing.T) {
+ // Use a new goroutine so that we get a small stack.
+ c := make(chan int)
+ go func() {
+ c <- int(C.returnAfterGrowFromGo())
+ }()
+ if got, want := <-c, 129*128/2; got != want {
+ t.Errorf("got %d want %d", got, want)
+ }
+}
+
+//export goReturnVal
+func goReturnVal() (r C.int) {
+ // Force a stack copy.
+ var f func(int) int
+ f = func(i int) int {
+ var buf [256]byte
+ use(buf[:])
+ if i == 0 {
+ return 0
+ }
+ return i + f(i-1)
+ }
+ r = C.int(f(128))
+ return
+}
+
func testCallbackStack(t *testing.T) {
// Make cgo call and callback with different amount of stack stack available.
// We do not do any explicit checks, just ensure that it does not crash.
// so that they can use cgo (import "C").
// These wrappers are here for gotest to find.
-func TestAlign(t *testing.T) { testAlign(t) }
-func TestConst(t *testing.T) { testConst(t) }
-func TestEnum(t *testing.T) { testEnum(t) }
-func TestAtol(t *testing.T) { testAtol(t) }
-func TestErrno(t *testing.T) { testErrno(t) }
-func TestMultipleAssign(t *testing.T) { testMultipleAssign(t) }
-func TestUnsignedInt(t *testing.T) { testUnsignedInt(t) }
-func TestCallback(t *testing.T) { testCallback(t) }
-func TestCallbackGC(t *testing.T) { testCallbackGC(t) }
-func TestCallbackPanic(t *testing.T) { testCallbackPanic(t) }
-func TestCallbackPanicLoop(t *testing.T) { testCallbackPanicLoop(t) }
-func TestCallbackPanicLocked(t *testing.T) { testCallbackPanicLocked(t) }
-func TestPanicFromC(t *testing.T) { testPanicFromC(t) }
-func TestAllocateFromC(t *testing.T) { testAllocateFromC(t) }
-func TestZeroArgCallback(t *testing.T) { testZeroArgCallback(t) }
-func TestBlocking(t *testing.T) { testBlocking(t) }
-func Test1328(t *testing.T) { test1328(t) }
-func TestParallelSleep(t *testing.T) { testParallelSleep(t) }
-func TestSetEnv(t *testing.T) { testSetEnv(t) }
-func TestHelpers(t *testing.T) { testHelpers(t) }
-func TestLibgcc(t *testing.T) { testLibgcc(t) }
-func Test1635(t *testing.T) { test1635(t) }
-func TestPrintf(t *testing.T) { testPrintf(t) }
-func Test4029(t *testing.T) { test4029(t) }
-func TestBoolAlign(t *testing.T) { testBoolAlign(t) }
-func Test3729(t *testing.T) { test3729(t) }
-func Test3775(t *testing.T) { test3775(t) }
-func TestCthread(t *testing.T) { testCthread(t) }
-func TestCallbackCallers(t *testing.T) { testCallbackCallers(t) }
-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 Test6833(t *testing.T) { test6833(t) }
-func Test3250(t *testing.T) { test3250(t) }
-func TestCallbackStack(t *testing.T) { testCallbackStack(t) }
-func TestFpVar(t *testing.T) { testFpVar(t) }
-func Test4339(t *testing.T) { test4339(t) }
-func Test6390(t *testing.T) { test6390(t) }
-func Test5986(t *testing.T) { test5986(t) }
-func Test7665(t *testing.T) { test7665(t) }
-func TestNaming(t *testing.T) { testNaming(t) }
-func Test7560(t *testing.T) { test7560(t) }
-func Test5242(t *testing.T) { test5242(t) }
-func Test8092(t *testing.T) { test8092(t) }
-func Test7978(t *testing.T) { test7978(t) }
-func Test8694(t *testing.T) { test8694(t) }
+func TestAlign(t *testing.T) { testAlign(t) }
+func TestConst(t *testing.T) { testConst(t) }
+func TestEnum(t *testing.T) { testEnum(t) }
+func TestAtol(t *testing.T) { testAtol(t) }
+func TestErrno(t *testing.T) { testErrno(t) }
+func TestMultipleAssign(t *testing.T) { testMultipleAssign(t) }
+func TestUnsignedInt(t *testing.T) { testUnsignedInt(t) }
+func TestCallback(t *testing.T) { testCallback(t) }
+func TestCallbackGC(t *testing.T) { testCallbackGC(t) }
+func TestCallbackPanic(t *testing.T) { testCallbackPanic(t) }
+func TestCallbackPanicLoop(t *testing.T) { testCallbackPanicLoop(t) }
+func TestCallbackPanicLocked(t *testing.T) { testCallbackPanicLocked(t) }
+func TestPanicFromC(t *testing.T) { testPanicFromC(t) }
+func TestAllocateFromC(t *testing.T) { testAllocateFromC(t) }
+func TestZeroArgCallback(t *testing.T) { testZeroArgCallback(t) }
+func TestBlocking(t *testing.T) { testBlocking(t) }
+func Test1328(t *testing.T) { test1328(t) }
+func TestParallelSleep(t *testing.T) { testParallelSleep(t) }
+func TestSetEnv(t *testing.T) { testSetEnv(t) }
+func TestHelpers(t *testing.T) { testHelpers(t) }
+func TestLibgcc(t *testing.T) { testLibgcc(t) }
+func Test1635(t *testing.T) { test1635(t) }
+func TestPrintf(t *testing.T) { testPrintf(t) }
+func Test4029(t *testing.T) { test4029(t) }
+func TestBoolAlign(t *testing.T) { testBoolAlign(t) }
+func Test3729(t *testing.T) { test3729(t) }
+func Test3775(t *testing.T) { test3775(t) }
+func TestCthread(t *testing.T) { testCthread(t) }
+func TestCallbackCallers(t *testing.T) { testCallbackCallers(t) }
+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 Test6833(t *testing.T) { test6833(t) }
+func Test3250(t *testing.T) { test3250(t) }
+func TestCallbackStack(t *testing.T) { testCallbackStack(t) }
+func TestFpVar(t *testing.T) { testFpVar(t) }
+func Test4339(t *testing.T) { test4339(t) }
+func Test6390(t *testing.T) { test6390(t) }
+func Test5986(t *testing.T) { test5986(t) }
+func Test7665(t *testing.T) { test7665(t) }
+func TestNaming(t *testing.T) { testNaming(t) }
+func Test7560(t *testing.T) { test7560(t) }
+func Test5242(t *testing.T) { test5242(t) }
+func Test8092(t *testing.T) { test8092(t) }
+func Test7978(t *testing.T) { test7978(t) }
+func Test8694(t *testing.T) { test8694(t) }
+func TestReturnAfterGrow(t *testing.T) { testReturnAfterGrow(t) }
+func TestReturnAfterGrowFromGo(t *testing.T) { testReturnAfterGrowFromGo(t) }
func BenchmarkCgoCall(b *testing.B) { benchCgoCall(b) }
fmt.Fprintf(fm, "int main() { return 0; }\n")
if *importRuntimeCgo {
fmt.Fprintf(fm, "void crosscall2(void(*fn)(void*, int), void *a, int c) { }\n")
+ fmt.Fprintf(fm, "char* cgo_topofstack(void) { return (char*)0; }\n")
} else {
// If we're not importing runtime/cgo, we *are* runtime/cgo,
// which provides crosscall2. We just need a prototype.
// Use packed attribute to force no padding in this struct in case
// gcc has different packing requirements.
fmt.Fprintf(fgcc, "\t%s %v *a = v;\n", ctype, p.packedAttribute())
+ if n.FuncType.Result != nil {
+ // Save the stack top for use below.
+ fmt.Fprintf(fgcc, "\tchar *stktop = cgo_topofstack();\n")
+ }
fmt.Fprintf(fgcc, "\t")
if t := n.FuncType.Result; t != nil {
- fmt.Fprintf(fgcc, "a->r = ")
+ fmt.Fprintf(fgcc, "__typeof__(a->r) r = ")
if c := t.C.String(); c[len(c)-1] == '*' {
fmt.Fprint(fgcc, "(__typeof__(a->r)) ")
}
fmt.Fprintf(fgcc, "a->p%d", i)
}
fmt.Fprintf(fgcc, ");\n")
+ if n.FuncType.Result != nil {
+ // The cgo call may have caused a stack copy (via a callback).
+ // Adjust the return value pointer appropriately.
+ fmt.Fprintf(fgcc, "\ta = (void*)((char*)a + (cgo_topofstack() - stktop));\n")
+ // Save the return value.
+ fmt.Fprintf(fgcc, "\ta->r = r;\n")
+ }
if n.AddError {
fmt.Fprintf(fgcc, "\treturn errno;\n")
}
__cgo_size_assert(float, 4)
__cgo_size_assert(double, 8)
+extern char* cgo_topofstack(void);
+
#include <errno.h>
#include <string.h>
`