From fc9a18f16bd4c133ddb60aded9901fd53ccb042d Mon Sep 17 00:00:00 2001 From: Andrew Gerrand Date: Tue, 23 Jul 2013 09:40:49 +1000 Subject: [release-branch.go1.1] cmd/8g: Make clearfat non-interleaved with pointer calculations. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit ««« CL 11383043 / dc24634de6c5 cmd/8g: Make clearfat non-interleaved with pointer calculations. clearfat (used to zero initialize structures) will use AX for x86 block ops. If we write to AX while calculating the dest pointer, we will fill the structure with incorrect values. Since 64-bit arithmetic uses AX to synthesize a 64-bit register, getting an adress by indexing with 64-bit ops can clobber the register. Fixes #5820. R=golang-dev, rsc CC=golang-dev https://golang.org/cl/11383043 »»» Update #5928 R=golang-dev, bradfitz CC=golang-dev https://golang.org/cl/11698043 --- src/cmd/8g/ggen.c | 2 +- test/fixedbugs/issue5820.go | 18 ++++++++++++++++++ 2 files changed, 19 insertions(+), 1 deletion(-) create mode 100644 test/fixedbugs/issue5820.go diff --git a/src/cmd/8g/ggen.c b/src/cmd/8g/ggen.c index 70148106c4..b0154bb80c 100644 --- a/src/cmd/8g/ggen.c +++ b/src/cmd/8g/ggen.c @@ -78,9 +78,9 @@ clearfat(Node *nl) c = w % 4; // bytes q = w / 4; // quads - gconreg(AMOVL, 0, D_AX); nodreg(&n1, types[tptr], D_DI); agen(nl, &n1); + gconreg(AMOVL, 0, D_AX); if(q >= 4) { gconreg(AMOVL, q, D_CX); diff --git a/test/fixedbugs/issue5820.go b/test/fixedbugs/issue5820.go new file mode 100644 index 0000000000..94de06d57d --- /dev/null +++ b/test/fixedbugs/issue5820.go @@ -0,0 +1,18 @@ +// run + +// Copyright 2013 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. + +// issue 5820: register clobber when clearfat and 64 bit arithmetic is interleaved. + +package main + +func main() { + array := make([][]int, 2) + index := uint64(1) + array[index] = nil + if array[1] != nil { + panic("array[1] != nil") + } +} -- cgit v1.2.3-54-g00ecf