From 1b58d4536a561f28bf935dcb29b483c52a6bf4c6 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Mon, 23 May 2011 21:07:39 +0000 Subject: [PATCH] When checking for signed multiplication overflow, watch out for INT_MIN and -1. This fixes PR9845. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131919 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/LoopStrengthReduce.cpp | 2 ++ test/CodeGen/X86/lsr-overflow.ll | 18 ++++++++++++++++++ 2 files changed, 20 insertions(+) diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 204ce36b8a4..73ebd618a0c 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -2522,6 +2522,8 @@ void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx, // Check that multiplying with the unfolded offset doesn't overflow. if (F.UnfoldedOffset != 0) { + if (F.UnfoldedOffset == INT64_MIN && Factor == -1) + continue; F.UnfoldedOffset = (uint64_t)F.UnfoldedOffset * Factor; if (F.UnfoldedOffset / Factor != Base.UnfoldedOffset) continue; diff --git a/test/CodeGen/X86/lsr-overflow.ll b/test/CodeGen/X86/lsr-overflow.ll index 5bc4f7e96a0..09c1c07ef3d 100644 --- a/test/CodeGen/X86/lsr-overflow.ll +++ b/test/CodeGen/X86/lsr-overflow.ll @@ -25,3 +25,21 @@ __ABContainsLabel.exit: %cmp = icmp eq i64 %indvar, 9223372036854775807 ret i1 %cmp } + +define void @func_37() noreturn nounwind readonly { +entry: + br label %for.body + +for.body: ; preds = %for.inc8, %entry + %indvar = phi i64 [ 0, %entry ], [ %indvar.next, %for.inc8 ] + %sub.i = add i64 undef, %indvar + %cmp.i = icmp eq i64 %sub.i, -9223372036854775808 + br i1 undef, label %for.inc8, label %for.cond4 + +for.cond4: ; preds = %for.cond4, %for.body + br label %for.cond4 + +for.inc8: ; preds = %for.body + %indvar.next = add i64 %indvar, 1 + br label %for.body +}