From c606c3ff911eddcbf8bab95e67c7d8c1f69a493e Mon Sep 17 00:00:00 2001 From: Nuno Lopes Date: Fri, 20 Jul 2012 23:07:40 +0000 Subject: [PATCH] baby steps toward fixing some problems with inbound GEPs that overflow, as discussed 2 months ago or so. Make sure we do not emit index computations with NSW flags so that we dont get an undef value if the GEP overflows git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160589 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Transforms/Utils/Local.h | 7 +++++-- lib/Analysis/MemoryBuiltins.cpp | 2 +- test/Instrumentation/BoundsChecking/simple.ll | 10 ++++++++++ 3 files changed, 16 insertions(+), 3 deletions(-) diff --git a/include/llvm/Transforms/Utils/Local.h b/include/llvm/Transforms/Utils/Local.h index 84c0c5862ed..495eab73289 100644 --- a/include/llvm/Transforms/Utils/Local.h +++ b/include/llvm/Transforms/Utils/Local.h @@ -168,15 +168,18 @@ static inline unsigned getKnownAlignment(Value *V, const TargetData *TD = 0) { /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the /// code necessary to compute the offset from the base pointer (without adding /// in the base pointer). Return the result as a signed integer of intptr size. +/// When NoAssumptions is true, no assumptions about index computation not +/// overflowing is made. template -Value *EmitGEPOffset(IRBuilderTy *Builder, const TargetData &TD, User *GEP) { +Value *EmitGEPOffset(IRBuilderTy *Builder, const TargetData &TD, User *GEP, + bool NoAssumptions = false) { gep_type_iterator GTI = gep_type_begin(GEP); Type *IntPtrTy = TD.getIntPtrType(GEP->getContext()); Value *Result = Constant::getNullValue(IntPtrTy); // If the GEP is inbounds, we know that none of the addressing operations will // overflow in an unsigned sense. - bool isInBounds = cast(GEP)->isInBounds(); + bool isInBounds = cast(GEP)->isInBounds() && !NoAssumptions; // Build a mask for high order bits. unsigned IntPtrWidth = TD.getPointerSizeInBits(); diff --git a/lib/Analysis/MemoryBuiltins.cpp b/lib/Analysis/MemoryBuiltins.cpp index 39edaaf1c49..8d99ec3e564 100644 --- a/lib/Analysis/MemoryBuiltins.cpp +++ b/lib/Analysis/MemoryBuiltins.cpp @@ -645,7 +645,7 @@ ObjectSizeOffsetEvaluator::visitGEPOperator(GEPOperator &GEP) { if (!bothKnown(PtrData)) return unknown(); - Value *Offset = EmitGEPOffset(&Builder, *TD, &GEP); + Value *Offset = EmitGEPOffset(&Builder, *TD, &GEP, /*NoAssumptions=*/true); Offset = Builder.CreateAdd(PtrData.second, Offset); return std::make_pair(PtrData.first, Offset); } diff --git a/test/Instrumentation/BoundsChecking/simple.ll b/test/Instrumentation/BoundsChecking/simple.ll index 3d532c3cf3b..16870c78a87 100644 --- a/test/Instrumentation/BoundsChecking/simple.ll +++ b/test/Instrumentation/BoundsChecking/simple.ll @@ -116,3 +116,13 @@ define void @f11(i128* byval %x) nounwind { %3 = load i8* %2, align 4 ret void } + +; CHECK: @f12 +define i64 @f12(i64 %x, i64 %y) nounwind { + %1 = tail call i8* @calloc(i64 1, i64 %x) +; CHECK: mul i64 %y, 8 + %2 = bitcast i8* %1 to i64* + %3 = getelementptr inbounds i64* %2, i64 %y + %4 = load i64* %3, align 8 + ret i64 %4 +}