From 7e9d55eeeb183ee95d26b3ed4ff171902605decf Mon Sep 17 00:00:00 2001 From: David Chase Date: Mon, 25 Jun 2018 15:26:45 -0400 Subject: cmd/compile: avoid remainder in loopbce when increment=0 For non-unit increment, loopbce checks to see if the increment evenly divides the difference between (constant) loop start and end. This test panics when the increment is zero. Fix: check for zero, if found, don't optimize the loop. Also added missing copyright notice to loopbce.go. Fixes #26043. Change-Id: I5f460104879cacc94481949234c9ce8c519d6380 Reviewed-on: https://go-review.googlesource.com/120759 Run-TryBot: David Chase TryBot-Result: Gobot Gobot Reviewed-by: Brad Fitzpatrick --- src/cmd/compile/internal/ssa/loopbce.go | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'src/cmd/compile') diff --git a/src/cmd/compile/internal/ssa/loopbce.go b/src/cmd/compile/internal/ssa/loopbce.go index 0c09de0bfc..2ab05711ad 100644 --- a/src/cmd/compile/internal/ssa/loopbce.go +++ b/src/cmd/compile/internal/ssa/loopbce.go @@ -1,3 +1,7 @@ +// Copyright 2018 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 ssa import "fmt" @@ -154,7 +158,7 @@ nextb: // if the increment is ±1 or when the limits are constants. if inc.AuxInt != 1 && inc.AuxInt != -1 { ok := false - if min.Op == OpConst64 && max.Op == OpConst64 { + if min.Op == OpConst64 && max.Op == OpConst64 && inc.AuxInt != 0 { if max.AuxInt > min.AuxInt && max.AuxInt%inc.AuxInt == min.AuxInt%inc.AuxInt { // handle overflow ok = true } -- cgit v1.3