runtime: fix gogetcallerpc.

Make assembly govet-clean.
Clean up fixes for CL 93380044.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/107160047

src/pkg/runtime/asm_386.s

@@ -782,9 +782,9 @@ TEXT runtime·getcallerpc(SB),NOSPLIT,$0-4
 	RET
 
 TEXT runtime·gogetcallerpc(SB),NOSPLIT,$0-8
-	MOVL	x+0(FP),AX		// addr of first arg
+	MOVL	p+0(FP),AX		// addr of first arg
 	MOVL	-4(AX),AX		// get calling pc
-	MOVL	AX, r+4(FP)
+	MOVL	AX, ret+4(FP)
 	RET
 
 TEXT runtime·setcallerpc(SB),NOSPLIT,$0-8

src/pkg/runtime/asm_amd64.s

@@ -858,10 +858,10 @@ TEXT runtime·getcallerpc(SB),NOSPLIT,$0-8
 	MOVQ	-8(AX),AX		// get calling pc
 	RET
 
-TEXT runtime·gogetcallerpc(SB),NOSPLIT,$0-8
-	MOVQ	x+0(FP),AX		// addr of first arg
+TEXT runtime·gogetcallerpc(SB),NOSPLIT,$0-16
+	MOVQ	p+0(FP),AX		// addr of first arg
 	MOVQ	-8(AX),AX		// get calling pc
-	MOVQ	AX,r+4(FP)
+	MOVQ	AX,ret+8(FP)
 	RET
 
 TEXT runtime·setcallerpc(SB),NOSPLIT,$0-16

src/pkg/runtime/asm_amd64p32.s

@@ -664,9 +664,9 @@ TEXT runtime·getcallerpc(SB),NOSPLIT,$0-8
 	RET
 
 TEXT runtime·gogetcallerpc(SB),NOSPLIT,$0-8
-	MOVL	x+0(FP),AX		// addr of first arg
+	MOVL	p+0(FP),AX		// addr of first arg
 	MOVL	-8(AX),AX		// get calling pc
-	MOVL	AX, r+4(FP)
+	MOVL	AX, ret+4(FP)
 	RET
 
 TEXT runtime·setcallerpc(SB),NOSPLIT,$0-16
@@ -686,7 +686,7 @@ TEXT runtime·cputicks(SB),NOSPLIT,$0-0
 	ADDQ	DX, AX
 	RET
 
-TEXT runtime·stackguard(SB),NOSPLIT,$0-16
+TEXT runtime·stackguard(SB),NOSPLIT,$0-8
 	MOVL	SP, DX
 	MOVL	DX, sp+0(FP)
 	get_tls(CX)

src/pkg/runtime/asm_arm.s

@@ -561,7 +561,7 @@ TEXT runtime·getcallerpc(SB),NOSPLIT,$-4-4
 	RET
 
 TEXT runtime·gogetcallerpc(SB),NOSPLIT,$-4-8
-	MOVW	R14, 4(FP)
+	MOVW	R14, ret+4(FP)
 	RET
 
 TEXT runtime·setcallerpc(SB),NOSPLIT,$-4-8

src/pkg/runtime/string.go

@@ -143,15 +143,19 @@ func slicerunetostring(a []rune) string {
 	return s[:size2]
 }
 
+type stringStruct struct {
+	str *byte
+	len int
+}
+
 func cstringToGo(str uintptr) (s string) {
-	// Note: we need i to be the same type as _string.len and to start at 0.
-	i := _string{}.len
+	i := 0
 	for ; ; i++ {
 		if *(*byte)(unsafe.Pointer(str + uintptr(i))) == 0 {
 			break
 		}
 	}
-	t := (*_string)(unsafe.Pointer(&s))
+	t := (*stringStruct)(unsafe.Pointer(&s))
 	t.str = (*byte)(unsafe.Pointer(str))
 	t.len = i
 	return

src/pkg/runtime/stubs.goc

@@ -19,9 +19,8 @@ package runtime
 //    out to only NOSPLIT functions (recursively).
 // 2) Functions should not block.
 
-// During conversion, we can still call out to splittable
-// functions.  But once conversion is done the invariants
-// above should hold.
+// These invariants do not hold yet but will be established once we have
+// finished converting runtime support code from C to Go.
 
 #pragma textflag NOSPLIT
 func rawstring(size intgo) (s String, b Slice) {