runtime/race: update race runtime

This updates the runtime to HEAD to keep it aligned and fixes some bugs.

http://llvm.org/viewvc/llvm-project?view=revision&revision=285454
fixes the crash on darwin related to unaligned data section (#17065).

http://llvm.org/viewvc/llvm-project?view=revision&revision=285451
enables core dumps by default (#16527).

http://llvm.org/viewvc/llvm-project?view=revision&revision=285455
adds a hook to obtain number of races reported so far (#15972).
Can now be obtained with:

//go:nosplit
func RaceReportCount() int {
	var n uint64
	racecall(&__tsan_report_count, uintptr(unsafe.Pointer(&n)), 0, 0, 0)
	return int(n)
}

Fixes #16527.
Fixes #17065.
Update #15972.

Change-Id: I8f869cb6275c9521a47303f3810a9965e9314357
Reviewed-on: https://go-review.googlesource.com/32160
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/dist/test.go

@@ -1061,8 +1061,7 @@ func (t *tester) raceTest(dt *distTest) error {
 	// The race builder should catch any error here, but doesn't.
 	// TODO(iant): Figure out how to catch this.
 	// t.addCmd(dt, "src", "go", "test", "-race", "-run=TestParallelTest", "cmd/go")
-	// TODO: Remove t.goos != "darwin" when issue 17065 is fixed.
-	if t.cgoEnabled && t.goos != "darwin" {
+	if t.cgoEnabled {
 		env := mergeEnvLists([]string{"GOTRACEBACK=2"}, os.Environ())
 		cmd := t.addCmd(dt, "misc/cgo/test", "go", "test", "-race", "-short", t.runFlag(""))
 		cmd.Env = env

src/runtime/race.go

@@ -176,6 +176,9 @@ var __tsan_go_ignore_sync_begin byte
 //go:linkname __tsan_go_ignore_sync_end __tsan_go_ignore_sync_end
 var __tsan_go_ignore_sync_end byte
 
+//go:linkname __tsan_report_count __tsan_report_count
+var __tsan_report_count byte
+
 // Mimic what cmd/cgo would do.
 //go:cgo_import_static __tsan_init
 //go:cgo_import_static __tsan_fini
@@ -192,6 +195,7 @@ var __tsan_go_ignore_sync_end byte
 //go:cgo_import_static __tsan_release_merge
 //go:cgo_import_static __tsan_go_ignore_sync_begin
 //go:cgo_import_static __tsan_go_ignore_sync_end
+//go:cgo_import_static __tsan_report_count
 
 // These are called from race_amd64.s.
 //go:cgo_import_static __tsan_read

src/runtime/race/README

@@ -4,4 +4,4 @@ the LLVM project (http://llvm.org/git/compiler-rt.git).
 
 To update the .syso files use golang.org/x/build/cmd/racebuild.
 
-Current runtime is built on rev e35e7c00b5c7e7ee5e24d537b80cb0d34cebb038.
+Current runtime is built on rev 68e1532492f9b3fce0e9024f3c31411105965b11.