From 489c1485780f6326fb5f446bd9d97dff2ff0abcf Mon Sep 17 00:00:00 2001 From: Keith Randall Date: Wed, 29 Jun 2022 13:22:59 -0700 Subject: [release-branch.go1.17] cmd/compile: fix prove pass when upper condition is <= maxint When the terminating condition is <= X, we need to make sure that X+step doesn't overflow. Fixes #53617 Change-Id: I36e5384d05b4d7168e48db6094200fcae409bfe5 Reviewed-on: https://go-review.googlesource.com/c/go/+/415219 Reviewed-by: Than McIntosh Run-TryBot: David Chase Reviewed-by: David Chase TryBot-Result: Gopher Robot Run-TryBot: Keith Randall (cherry picked from commit 31b8c23c5702f129aca9241bbb2132c90b1929cc) Reviewed-on: https://go-review.googlesource.com/c/go/+/415415 Reviewed-by: Keith Randall --- src/cmd/compile/internal/ssa/loopbce.go | 7 ++++++ test/fixedbugs/issue53600.go | 42 +++++++++++++++++++++++++++++++++ test/fixedbugs/issue53600.out | 8 +++++++ 3 files changed, 57 insertions(+) create mode 100644 test/fixedbugs/issue53600.go create mode 100644 test/fixedbugs/issue53600.out diff --git a/src/cmd/compile/internal/ssa/loopbce.go b/src/cmd/compile/internal/ssa/loopbce.go index 5a4bc1d60a..fd03efb417 100644 --- a/src/cmd/compile/internal/ssa/loopbce.go +++ b/src/cmd/compile/internal/ssa/loopbce.go @@ -159,6 +159,13 @@ func findIndVar(f *Func) []indVar { step = -step } + if flags&indVarMaxInc != 0 && max.Op == OpConst64 && max.AuxInt+step < max.AuxInt { + // For a <= comparison, we need to make sure that a value equal to + // max can be incremented without overflowing. + // (For a < comparison, the %step check below ensures no overflow.) + continue + } + // Up to now we extracted the induction variable (ind), // the increment delta (inc), the temporary sum (nxt), // the mininum value (min) and the maximum value (max). diff --git a/test/fixedbugs/issue53600.go b/test/fixedbugs/issue53600.go new file mode 100644 index 0000000000..fd3a9e5e47 --- /dev/null +++ b/test/fixedbugs/issue53600.go @@ -0,0 +1,42 @@ +// run + +// Copyright 2022 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 main + +import "math" + +func main() { + f() + g() + h() +} +func f() { + for i := int64(math.MaxInt64); i <= math.MaxInt64; i++ { + if i < 0 { + println("done") + return + } + println(i, i < 0) + } +} +func g() { + for i := int64(math.MaxInt64) - 1; i <= math.MaxInt64; i++ { + if i < 0 { + println("done") + return + } + println(i, i < 0) + } +} +func h() { + for i := int64(math.MaxInt64) - 2; i <= math.MaxInt64; i += 2 { + if i < 0 { + println("done") + return + } + println(i, i < 0) + } +} diff --git a/test/fixedbugs/issue53600.out b/test/fixedbugs/issue53600.out new file mode 100644 index 0000000000..5590c7dcfb --- /dev/null +++ b/test/fixedbugs/issue53600.out @@ -0,0 +1,8 @@ +9223372036854775807 false +done +9223372036854775806 false +9223372036854775807 false +done +9223372036854775805 false +9223372036854775807 false +done -- cgit v1.2.3-54-g00ecf