runtime: reimplement GODEBUG=cgocheck=2 as a GOEXPERIMENT

Move this knob from a binary-startup thing to a build-time thing.
This will enable followon optmizations to the write barrier.

Change-Id: Ic3323348621c76a7dc390c09ff55016b19c43018
Reviewed-on: https://go-review.googlesource.com/c/go/+/447778
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>

1 files changed, 17 insertions, 1 deletions

diff --git a/src/runtime/atomic_pointer.go b/src/runtime/atomic_pointer.go
index 25e0e651b4..26dfbfc2cc 100644
--- a/src/runtime/atomic_pointer.go
+++ b/src/runtime/atomic_pointer.go
@@ -5,6 +5,7 @@
 package runtime
 
 import (
+	"internal/goexperiment"
 	"runtime/internal/atomic"
 	"unsafe"
 )
@@ -21,7 +22,7 @@ import (
 func atomicwb(ptr *unsafe.Pointer, new unsafe.Pointer) {
 	slot := (*uintptr)(unsafe.Pointer(ptr))
 	if !getg().m.p.ptr().wbBuf.putFast(*slot, uintptr(new)) {
-		wbBufFlush(slot, uintptr(new))
+		wbBufFlush()
 	}
 }
 
@@ -32,6 +33,9 @@ func atomicstorep(ptr unsafe.Pointer, new unsafe.Pointer) {
 	if writeBarrier.enabled {
 		atomicwb((*unsafe.Pointer)(ptr), new)
 	}
+	if goexperiment.CgoCheck2 {
+		cgoCheckPtrWrite((*unsafe.Pointer)(ptr), new)
+	}
 	atomic.StorepNoWB(noescape(ptr), new)
 }
 
@@ -53,6 +57,9 @@ func atomic_casPointer(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool {
 	if writeBarrier.enabled {
 		atomicwb(ptr, new)
 	}
+	if goexperiment.CgoCheck2 {
+		cgoCheckPtrWrite(ptr, new)
+	}
 	return atomic.Casp1(ptr, old, new)
 }
 
@@ -69,6 +76,9 @@ func sync_atomic_StorePointer(ptr *unsafe.Pointer, new unsafe.Pointer) {
 	if writeBarrier.enabled {
 		atomicwb(ptr, new)
 	}
+	if goexperiment.CgoCheck2 {
+		cgoCheckPtrWrite(ptr, new)
+	}
 	sync_atomic_StoreUintptr((*uintptr)(unsafe.Pointer(ptr)), uintptr(new))
 }
 
@@ -81,6 +91,9 @@ func sync_atomic_SwapPointer(ptr *unsafe.Pointer, new unsafe.Pointer) unsafe.Poi
 	if writeBarrier.enabled {
 		atomicwb(ptr, new)
 	}
+	if goexperiment.CgoCheck2 {
+		cgoCheckPtrWrite(ptr, new)
+	}
 	old := unsafe.Pointer(sync_atomic_SwapUintptr((*uintptr)(noescape(unsafe.Pointer(ptr))), uintptr(new)))
 	return old
 }
@@ -94,5 +107,8 @@ func sync_atomic_CompareAndSwapPointer(ptr *unsafe.Pointer, old, new unsafe.Poin
 	if writeBarrier.enabled {
 		atomicwb(ptr, new)
 	}
+	if goexperiment.CgoCheck2 {
+		cgoCheckPtrWrite(ptr, new)
+	}
 	return sync_atomic_CompareAndSwapUintptr((*uintptr)(noescape(unsafe.Pointer(ptr))), uintptr(old), uintptr(new))
 }