From c0602603b20186228b4f89f265cb3f7665e06768 Mon Sep 17 00:00:00 2001 From: Keith Randall Date: Sun, 23 Aug 2020 11:52:53 -0700 Subject: [PATCH] runtime: implement StorepNoWB for wasm in assembly The second argument of StorepNoWB must be forced to escape. The current Go code does not explicitly enforce that property. By implementing in assembly, and not using go:noescape, we force the issue. Test is in CL 249761. Issue #40975. This CL is needed for CL 249917, which changes how go:notinheap works and breaks the previous StorepNoWB wasm code. I checked for other possible errors like this. This is the only go:notinheap that isn't in the runtime itself. Change-Id: I43400a806662655727c4a3baa8902b63bdc9fa57 Reviewed-on: https://go-review.googlesource.com/c/go/+/249962 Run-TryBot: Keith Randall TryBot-Result: Gobot Gobot Reviewed-by: Matthew Dempsky --- src/runtime/internal/atomic/asm_wasm.s | 10 ++++++++++ src/runtime/internal/atomic/atomic_wasm.go | 13 +++++-------- 2 files changed, 15 insertions(+), 8 deletions(-) create mode 100644 src/runtime/internal/atomic/asm_wasm.s diff --git a/src/runtime/internal/atomic/asm_wasm.s b/src/runtime/internal/atomic/asm_wasm.s new file mode 100644 index 00000000000..7c33cb1ee9b --- /dev/null +++ b/src/runtime/internal/atomic/asm_wasm.s @@ -0,0 +1,10 @@ +// Copyright 2020 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. + +#include "textflag.h" + +TEXT runtime∕internal∕atomic·StorepNoWB(SB), NOSPLIT, $0-16 + MOVD ptr+0(FP), R0 + MOVD val+8(FP), 0(R0) + RET diff --git a/src/runtime/internal/atomic/atomic_wasm.go b/src/runtime/internal/atomic/atomic_wasm.go index 9037c2f7c87..2c0c3a81740 100644 --- a/src/runtime/internal/atomic/atomic_wasm.go +++ b/src/runtime/internal/atomic/atomic_wasm.go @@ -153,14 +153,11 @@ func Store64(ptr *uint64, val uint64) { *ptr = val } -//go:notinheap -type noWB struct{} - -//go:noinline -//go:nosplit -func StorepNoWB(ptr unsafe.Pointer, val unsafe.Pointer) { - *(**noWB)(ptr) = (*noWB)(val) -} +// StorepNoWB performs *ptr = val atomically and without a write +// barrier. +// +// NO go:noescape annotation; see atomic_pointer.go. +func StorepNoWB(ptr unsafe.Pointer, val unsafe.Pointer) //go:nosplit //go:noinline