runtime: add atomic xchg64
It will be handy for network poller.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7429048
diff --git a/src/pkg/runtime/asm_amd64.s b/src/pkg/runtime/asm_amd64.s
index 9879584..696befd 100644
--- a/src/pkg/runtime/asm_amd64.s
+++ b/src/pkg/runtime/asm_amd64.s
@@ -442,6 +442,12 @@
XCHGL AX, 0(BX)
RET
+TEXT runtime·xchg64(SB), 7, $0
+ MOVQ 8(SP), BX
+ MOVQ 16(SP), AX
+ XCHGQ AX, 0(BX)
+ RET
+
TEXT runtime·procyield(SB),7,$0
MOVL 8(SP), AX
again:
diff --git a/src/pkg/runtime/atomic_386.c b/src/pkg/runtime/atomic_386.c
index 79b7cbf..1046eb8 100644
--- a/src/pkg/runtime/atomic_386.c
+++ b/src/pkg/runtime/atomic_386.c
@@ -30,3 +30,16 @@
}
return old+v;
}
+
+#pragma textflag 7
+uint64
+runtime·xchg64(uint64 volatile* addr, uint64 v)
+{
+ uint64 old;
+
+ old = *addr;
+ while(!runtime·cas64(addr, &old, v)) {
+ // nothing
+ }
+ return old;
+}
diff --git a/src/pkg/runtime/atomic_arm.c b/src/pkg/runtime/atomic_arm.c
index 0b54840..9193d59 100644
--- a/src/pkg/runtime/atomic_arm.c
+++ b/src/pkg/runtime/atomic_arm.c
@@ -123,6 +123,19 @@
#pragma textflag 7
uint64
+runtime·xchg64(uint64 volatile *addr, uint64 v)
+{
+ uint64 res;
+
+ runtime·lock(LOCK(addr));
+ res = *addr;
+ *addr = v;
+ runtime·unlock(LOCK(addr));
+ return res;
+}
+
+#pragma textflag 7
+uint64
runtime·atomicload64(uint64 volatile *addr)
{
uint64 res;
diff --git a/src/pkg/runtime/runtime.c b/src/pkg/runtime/runtime.c
index 4d57cba..d3ee2a0 100644
--- a/src/pkg/runtime/runtime.c
+++ b/src/pkg/runtime/runtime.c
@@ -156,6 +156,10 @@
runtime·throw("xadd64 failed");
if(runtime·atomicload64(&z64) != (2ull<<40)+2)
runtime·throw("xadd64 failed");
+ if(runtime·xchg64(&z64, (3ull<<40)+3) != (2ull<<40)+2)
+ runtime·throw("xchg64 failed");
+ if(runtime·atomicload64(&z64) != (3ull<<40)+3)
+ runtime·throw("xchg64 failed");
}
void
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index 585d6a5..8ed1843 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -691,6 +691,7 @@
uint32 runtime·xadd(uint32 volatile*, int32);
uint64 runtime·xadd64(uint64 volatile*, int64);
uint32 runtime·xchg(uint32 volatile*, uint32);
+uint64 runtime·xchg64(uint64 volatile*, uint64);
uint32 runtime·atomicload(uint32 volatile*);
void runtime·atomicstore(uint32 volatile*, uint32);
void runtime·atomicstore64(uint64 volatile*, uint64);
