Imported Upstream version 1.4upstream/1.4

1 files changed, 155 insertions, 0 deletions

diff --git a/src/runtime/atomic_arm.go b/src/runtime/atomic_arm.go
new file mode 100644
index 000000000..b1632cdd1
--- /dev/null
+++ b/src/runtime/atomic_arm.go
@@ -0,0 +1,155 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+import "unsafe"
+
+var locktab [57]struct {
+	l   mutex
+	pad [_CacheLineSize - unsafe.Sizeof(mutex{})]byte
+}
+
+func addrLock(addr *uint64) *mutex {
+	return &locktab[(uintptr(unsafe.Pointer(addr))>>3)%uintptr(len(locktab))].l
+}
+
+// Atomic add and return new value.
+//go:nosplit
+func xadd(val *uint32, delta int32) uint32 {
+	for {
+		oval := *val
+		nval := oval + uint32(delta)
+		if cas(val, oval, nval) {
+			return nval
+		}
+	}
+}
+
+//go:nosplit
+func xchg(addr *uint32, v uint32) uint32 {
+	for {
+		old := *addr
+		if cas(addr, old, v) {
+			return old
+		}
+	}
+}
+
+//go:nosplit
+func xchgp(addr *unsafe.Pointer, v unsafe.Pointer) unsafe.Pointer {
+	for {
+		old := *addr
+		if casp(addr, old, v) {
+			return old
+		}
+	}
+}
+
+//go:nosplit
+func xchguintptr(addr *uintptr, v uintptr) uintptr {
+	return uintptr(xchg((*uint32)(unsafe.Pointer(addr)), uint32(v)))
+}
+
+//go:nosplit
+func atomicload(addr *uint32) uint32 {
+	return xadd(addr, 0)
+}
+
+//go:nosplit
+func atomicloadp(addr unsafe.Pointer) unsafe.Pointer {
+	return unsafe.Pointer(uintptr(xadd((*uint32)(addr), 0)))
+}
+
+//go:nosplit
+func atomicstorep(addr unsafe.Pointer, v unsafe.Pointer) {
+	for {
+		old := *(*unsafe.Pointer)(addr)
+		if casp((*unsafe.Pointer)(addr), old, v) {
+			return
+		}
+	}
+}
+
+//go:nosplit
+func atomicstore(addr *uint32, v uint32) {
+	for {
+		old := *addr
+		if cas(addr, old, v) {
+			return
+		}
+	}
+}
+
+//go:nosplit
+func cas64(addr *uint64, old, new uint64) bool {
+	var ok bool
+	onM(func() {
+		lock(addrLock(addr))
+		if *addr == old {
+			*addr = new
+			ok = true
+		}
+		unlock(addrLock(addr))
+	})
+	return ok
+}
+
+//go:nosplit
+func xadd64(addr *uint64, delta int64) uint64 {
+	var r uint64
+	onM(func() {
+		lock(addrLock(addr))
+		r = *addr + uint64(delta)
+		*addr = r
+		unlock(addrLock(addr))
+	})
+	return r
+}
+
+//go:nosplit
+func xchg64(addr *uint64, v uint64) uint64 {
+	var r uint64
+	onM(func() {
+		lock(addrLock(addr))
+		r = *addr
+		*addr = v
+		unlock(addrLock(addr))
+	})
+	return r
+}
+
+//go:nosplit
+func atomicload64(addr *uint64) uint64 {
+	var r uint64
+	onM(func() {
+		lock(addrLock(addr))
+		r = *addr
+		unlock(addrLock(addr))
+	})
+	return r
+}
+
+//go:nosplit
+func atomicstore64(addr *uint64, v uint64) {
+	onM(func() {
+		lock(addrLock(addr))
+		*addr = v
+		unlock(addrLock(addr))
+	})
+}
+
+//go:nosplit
+func atomicor8(addr *uint8, v uint8) {
+	// Align down to 4 bytes and use 32-bit CAS.
+	uaddr := uintptr(unsafe.Pointer(addr))
+	addr32 := (*uint32)(unsafe.Pointer(uaddr &^ 3))
+	word := uint32(v) << ((uaddr & 3) * 8) // little endian
+	for {
+		old := *addr32
+		if cas(addr32, old, old|word) {
+			return
+		}
+	}
+}