From c8a47c4877889b42afc5e3804c0fc575770564f2 Mon Sep 17 00:00:00 2001 From: Ian Lance Taylor Date: Thu, 22 Jun 2017 14:33:13 +0000 Subject: [PATCH] runtime: avoid write barriers when calling deferred function Calling a deferred function currently requires changing from a uintptr to the function code to a Go function value. That is done by setting the value of a func local variable using unsafe.Pointer. The local variable will always be on the stack. Adjust the code that sets the local variable to avoid generating a write barrier. A write barrier is never needed here. Also, for deferreturn, we must avoid write barriers entirely when called from a cgo function; that requires more than just this, but this is a start. The test for this is runtime tests that use the go tool; these are not currently run, but they will be in the future. Reviewed-on: https://go-review.googlesource.com/46455 From-SVN: r249559 --- gcc/go/gofrontend/MERGE | 2 +- libgo/go/runtime/panic.go | 8 ++++---- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE index 8ce40175bb3..a8dba3608d0 100644 --- a/gcc/go/gofrontend/MERGE +++ b/gcc/go/gofrontend/MERGE @@ -1,4 +1,4 @@ -a459f1fdfe0bd365bf2def730e1529052c6487fd +73b14da15ec731837ce2a45db658142bfbf5fe22 The first line of this file holds the git revision number of the last merge done from the gofrontend repository. diff --git a/libgo/go/runtime/panic.go b/libgo/go/runtime/panic.go index bbd34b40131..de3c79fe6bf 100644 --- a/libgo/go/runtime/panic.go +++ b/libgo/go/runtime/panic.go @@ -194,7 +194,7 @@ func deferreturn(frame *bool) { // The gc compiler does this using assembler // code in jmpdefer. var fn func(unsafe.Pointer) - *(**uintptr)(unsafe.Pointer(&fn)) = &pfn + *(*uintptr)(unsafe.Pointer(&fn)) = uintptr(unsafe.Pointer(&pfn)) fn(d.arg) } @@ -259,7 +259,7 @@ func checkdefer(frame *bool) { gp._defer = d.link var fn func(unsafe.Pointer) - *(**uintptr)(unsafe.Pointer(&fn)) = &pfn + *(*uintptr)(unsafe.Pointer(&fn)) = uintptr(unsafe.Pointer(&pfn)) fn(d.arg) freedefer(d) @@ -345,7 +345,7 @@ func Goexit() { if pfn != 0 { var fn func(unsafe.Pointer) - *(**uintptr)(unsafe.Pointer(&fn)) = &pfn + *(*uintptr)(unsafe.Pointer(&fn)) = uintptr(unsafe.Pointer(&pfn)) fn(d.arg) } @@ -446,7 +446,7 @@ func gopanic(e interface{}) { if pfn != 0 { var fn func(unsafe.Pointer) - *(**uintptr)(unsafe.Pointer(&fn)) = &pfn + *(*uintptr)(unsafe.Pointer(&fn)) = uintptr(unsafe.Pointer(&pfn)) fn(d.arg) if p.recovered { -- 2.30.2