runtime: adjust program counters in race detector

In most cases we pass return PC to race detector,
and race runtime subtracts one from them.
However, in manual instrumentation in runtime
we pass function start PC to race runtime.
Race runtime can't distinguish these cases
and so it does not subtract one from top PC.
This leads to bogus line numbers in some cases.
Make it consistent and always pass what looks
like a return PC, so that race runtime can
subtract one and still get PC in the same function.

Also delete two unused functions.

Update #8053

Change-Id: I4242dec5e055e460c9a8990eaca1d085ae240ed2
Reviewed-on: https://go-review.googlesource.com/4902Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/runtime/race.go

@@ -23,6 +23,9 @@ func RaceSemrelease(s *uint32)
 // private interface for the runtime
 const raceenabled = true
 
+// For all functions accepting callerpc and pc,
+// callerpc is a return PC of the function that calls this function,
+// pc is start PC of the function that calls this function.
 func raceReadObjectPC(t *_type, addr unsafe.Pointer, callerpc, pc uintptr) {
 	kind := t.kind & kindMask
 	if kind == kindArray || kind == kindStruct {

src/runtime/race1.go

@@ -226,26 +226,6 @@ func racereadrangepc(addr unsafe.Pointer, sz, callpc, pc uintptr) {
 	}
 }
 
-//go:nosplit
-func racewriteobjectpc(addr unsafe.Pointer, t *_type, callpc, pc uintptr) {
-	kind := t.kind & _KindMask
-	if kind == _KindArray || kind == _KindStruct {
-		racewriterangepc(addr, t.size, callpc, pc)
-	} else {
-		racewritepc(addr, callpc, pc)
-	}
-}
-
-//go:nosplit
-func racereadobjectpc(addr unsafe.Pointer, t *_type, callpc, pc uintptr) {
-	kind := t.kind & _KindMask
-	if kind == _KindArray || kind == _KindStruct {
-		racereadrangepc(addr, t.size, callpc, pc)
-	} else {
-		racereadpc(addr, callpc, pc)
-	}
-}
-
 //go:nosplit
 func raceacquire(addr unsafe.Pointer) {
 	raceacquireg(getg(), addr)

src/runtime/race_amd64.s

@@ -58,6 +58,7 @@ TEXT	runtime·racereadpc(SB), NOSPLIT, $0-24
 	MOVQ	addr+0(FP), RARG1
 	MOVQ	callpc+8(FP), RARG2
 	MOVQ	pc+16(FP), RARG3
+	ADDQ	$1, RARG3 // pc is function start, tsan wants return address
 	// void __tsan_read_pc(ThreadState *thr, void *addr, void *callpc, void *pc);
 	MOVQ	$__tsan_read_pc(SB), AX
 	JMP	racecalladdr<>(SB)
@@ -81,6 +82,7 @@ TEXT	runtime·racewritepc(SB), NOSPLIT, $0-24
 	MOVQ	addr+0(FP), RARG1
 	MOVQ	callpc+8(FP), RARG2
 	MOVQ	pc+16(FP), RARG3
+	ADDQ	$1, RARG3 // pc is function start, tsan wants return address
 	// void __tsan_write_pc(ThreadState *thr, void *addr, void *callpc, void *pc);
 	MOVQ	$__tsan_write_pc(SB), AX
 	JMP	racecalladdr<>(SB)
@@ -105,6 +107,7 @@ TEXT	runtime·racereadrangepc1(SB), NOSPLIT, $0-24
 	MOVQ	addr+0(FP), RARG1
 	MOVQ	size+8(FP), RARG2
 	MOVQ	pc+16(FP), RARG3
+	ADDQ	$1, RARG3 // pc is function start, tsan wants return address
 	// void __tsan_read_range(ThreadState *thr, void *addr, uintptr size, void *pc);
 	MOVQ	$__tsan_read_range(SB), AX
 	JMP	racecalladdr<>(SB)
@@ -129,6 +132,7 @@ TEXT	runtime·racewriterangepc1(SB), NOSPLIT, $0-24
 	MOVQ	addr+0(FP), RARG1
 	MOVQ	size+8(FP), RARG2
 	MOVQ	pc+16(FP), RARG3
+	ADDQ	$1, RARG3 // pc is function start, tsan wants return address
 	// void __tsan_write_range(ThreadState *thr, void *addr, uintptr size, void *pc);
 	MOVQ	$__tsan_write_range(SB), AX
 	JMP	racecalladdr<>(SB)