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, 6 insertions, 3 deletions

diff --git a/src/runtime/runtime.go b/src/runtime/runtime.go
index 81d3e5b3c3..0bbe42739d 100644
--- a/src/runtime/runtime.go
+++ b/src/runtime/runtime.go
@@ -4,7 +4,10 @@
 
 package runtime
 
-import _ "unsafe" // for go:linkname
+import (
+	"runtime/internal/atomic"
+	_ "unsafe" // for go:linkname
+)
 
 //go:generate go run wincallback.go
 //go:generate go run mkduff.go
@@ -20,7 +23,7 @@ var tls0 [8]uintptr // available storage for m0's TLS; not necessarily used; opa
 
 // Note: Called by runtime/pprof in addition to runtime code.
 func tickspersecond() int64 {
-	r := int64(atomicload64(&ticks.val))
+	r := int64(atomic.Load64(&ticks.val))
 	if r != 0 {
 		return r
 	}
@@ -39,7 +42,7 @@ func tickspersecond() int64 {
 		if r == 0 {
 			r++
 		}
-		atomicstore64(&ticks.val, uint64(r))
+		atomic.Store64(&ticks.val, uint64(r))
 	}
 	unlock(&ticks.lock)
 	return r