From a121e24c541097b51309a06297005ac257b6728f Mon Sep 17 00:00:00 2001 From: Hans Wennborg Date: Tue, 16 Apr 2013 08:35:36 +0000 Subject: simplifycfg: Fix integer overflow converting switch into icmp. If a switch instruction has a case for every possible value of its type, with the same successor, SimplifyCFG would replace it with an icmp ult, but the computation of the bound overflows in that case, which inverts the test. Patch by Jed Davis! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179587 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Utils/SimplifyCFG.cpp | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'lib/Transforms/Utils') diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp index 681bf9c..6de602e 100644 --- a/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/lib/Transforms/Utils/SimplifyCFG.cpp @@ -3073,7 +3073,12 @@ static bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) { Value *Sub = SI->getCondition(); if (!Offset->isNullValue()) Sub = Builder.CreateAdd(Sub, Offset, Sub->getName()+".off"); - Value *Cmp = Builder.CreateICmpULT(Sub, NumCases, "switch"); + Value *Cmp; + // If NumCases overflowed, then all possible values jump to the successor. + if (NumCases->isNullValue() && SI->getNumCases() != 0) + Cmp = ConstantInt::getTrue(SI->getContext()); + else + Cmp = Builder.CreateICmpULT(Sub, NumCases, "switch"); BranchInst *NewBI = Builder.CreateCondBr( Cmp, SI->case_begin().getCaseSuccessor(), SI->getDefaultDest()); -- cgit v1.1