compiler: move slice construction to callers of makeslice

    
    This is the gccgo version of https://golang.org/cl/141822:
    
        Only return a pointer p to the new slices backing array from makeslice.
        Makeslice callers then construct sliceheader{p, len, cap} explictly
        instead of makeslice returning the slice.
    
    This change caused the GCC backend to break the runtime/pprof test by
    merging together the identical functions allocateReflectTransient and
    allocateTransient2M.  This caused the traceback to be other than
    expected.  Fix that by making the functions not identical.
    
    This is a step toward updating libgo to the Go1.12beta1 release.
    
    Reviewed-on: https://go-review.googlesource.com/c/155937

From-SVN: r267660

2 files changed, 5 insertions, 6 deletions

diff --git a/libgo/go/runtime/pprof/mprof_test.go b/libgo/go/runtime/pprof/mprof_test.go
index f428827..6fe892b 100644
--- a/libgo/go/runtime/pprof/mprof_test.go
+++ b/libgo/go/runtime/pprof/mprof_test.go
@@ -45,7 +45,7 @@ func allocatePersistent1K() {
 // Allocate transient memory using reflect.Call.
 
 func allocateReflectTransient() {
-	memSink = make([]byte, 2<<20)
+	memSink = make([]byte, 3<<20)
 }
 
 func allocateReflect() {
@@ -106,7 +106,7 @@ func TestMemoryProfiler(t *testing.T) {
 		// GC means that sometimes the value is not collected.
 		fmt.Sprintf(`(0|%v): (0|%v) \[%v: %v\] @( 0x[0-9,a-f]+)+
 #	0x[0-9,a-f]+	pprof\.allocateReflectTransient\+0x[0-9,a-f]+	.*/mprof_test.go:48
-`, memoryProfilerRun, (2<<20)*memoryProfilerRun, memoryProfilerRun, (2<<20)*memoryProfilerRun),
+`, memoryProfilerRun, (3<<20)*memoryProfilerRun, memoryProfilerRun, (3<<20)*memoryProfilerRun),
 	}
 
 	for _, test := range tests {
diff --git a/libgo/go/runtime/slice.go b/libgo/go/runtime/slice.go
index 2e874cc..7f9db4e 100644
--- a/libgo/go/runtime/slice.go
+++ b/libgo/go/runtime/slice.go
@@ -61,7 +61,7 @@ func panicmakeslicecap() {
 	panic(errorString("makeslice: cap out of range"))
 }
 
-func makeslice(et *_type, len, cap int) slice {
+func makeslice(et *_type, len, cap int) unsafe.Pointer {
 	// NOTE: The len > maxElements check here is not strictly necessary,
 	// but it produces a 'len out of range' error instead of a 'cap out of range' error
 	// when someone does make([]T, bignumber). 'cap out of range' is true too,
@@ -76,11 +76,10 @@ func makeslice(et *_type, len, cap int) slice {
 		panicmakeslicecap()
 	}
 
-	p := mallocgc(et.size*uintptr(cap), et, true)
-	return slice{p, len, cap}
+	return mallocgc(et.size*uintptr(cap), et, true)
 }
 
-func makeslice64(et *_type, len64, cap64 int64) slice {
+func makeslice64(et *_type, len64, cap64 int64) unsafe.Pointer {
 	len := int(len64)
 	if int64(len) != len64 {
 		panicmakeslicelen()