runtime: break atomics out into package runtime/internal/atomic

This change breaks out most of the atomics functions in the runtime
into package runtime/internal/atomic. It adds some basic support
in the toolchain for runtime packages, and also modifies linux/arm
atomics to remove the dependency on the runtime's mutex. The mutexes
have been replaced with spinlocks.

all trybots are happy!
In addition to the trybots, I've tested on the darwin/arm64 builder,
on the darwin/arm builder, and on a ppc64le machine.

Change-Id: I6698c8e3cf3834f55ce5824059f44d00dc8e3c2f
Reviewed-on: https://go-review.googlesource.com/14204
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/src/runtime/atomic_pointer.go b/src/runtime/atomic_pointer.go
index ec2ea8a338..bd21b49945 100644
--- a/src/runtime/atomic_pointer.go
+++ b/src/runtime/atomic_pointer.go
@@ -4,7 +4,10 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"runtime/internal/atomic"
+	"unsafe"
+)
 
 // These functions cannot have go:noescape annotations,
 // because while ptr does not escape, new does.
@@ -18,13 +21,13 @@ import "unsafe"
 
 //go:nosplit
 func atomicstorep(ptr unsafe.Pointer, new unsafe.Pointer) {
-	atomicstorep1(noescape(ptr), new)
+	atomic.Storep1(noescape(ptr), new)
 	writebarrierptr_nostore((*uintptr)(ptr), uintptr(new))
 }
 
 //go:nosplit
 func casp(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool {
-	if !casp1((*unsafe.Pointer)(noescape(unsafe.Pointer(ptr))), noescape(old), new) {
+	if !atomic.Casp1((*unsafe.Pointer)(noescape(unsafe.Pointer(ptr))), noescape(old), new) {
 		return false
 	}
 	writebarrierptr_nostore((*uintptr)(unsafe.Pointer(ptr)), uintptr(new))
@@ -42,7 +45,7 @@ func sync_atomic_StoreUintptr(ptr *uintptr, new uintptr)
 //go:nosplit
 func sync_atomic_StorePointer(ptr *unsafe.Pointer, new unsafe.Pointer) {
 	sync_atomic_StoreUintptr((*uintptr)(unsafe.Pointer(ptr)), uintptr(new))
-	atomicstorep1(noescape(unsafe.Pointer(ptr)), new)
+	atomic.Storep1(noescape(unsafe.Pointer(ptr)), new)
 	writebarrierptr_nostore((*uintptr)(unsafe.Pointer(ptr)), uintptr(new))
 }