From 7902405c42ffe37f7e862dc9e442278394dec0c2 Mon Sep 17 00:00:00 2001 From: Florian Hahn Date: Fri, 4 Jan 2019 14:53:22 +0000 Subject: [ValueTracking] Fix a misuse of APInt in GetPointerBaseWithConstantOffset GetPointerBaseWithConstantOffset include this code, where ByteOffset and GEPOffset are both of type llvm::APInt : ByteOffset += GEPOffset.getSExtValue(); The problem with this line is that getSExtValue() returns an int64_t, but the += matches an overload for uint64_t. The problem is that the resulting APInt is no longer considered to be signed. That in turn causes assertion failures later on if the relevant pointer type is > 64 bits in width and the GEPOffset was negative. Changing it to ByteOffset += GEPOffset.sextOrTrunc(ByteOffset.getBitWidth()); resolves the issue and explicitly performs the sign-extending or truncation. Additionally, instead of asserting later if the result is > 64 bits, it breaks out of the loop in that case. See also https://reviews.llvm.org/D24729 https://reviews.llvm.org/D24772 This commit must be merged after D38662 in order for the test to pass. Patch by Michael Ferguson . Reviewers: reames, sanjoy, hfinkel Reviewed By: hfinkel Differential Revision: https://reviews.llvm.org/D38501 llvm-svn: 350395 --- llvm/lib/Analysis/ValueTracking.cpp | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'llvm/lib/Analysis/ValueTracking.cpp') diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index efbab47406c..3c4cf1d88f9 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -3389,7 +3389,14 @@ Value *llvm::GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset, if (!GEP->accumulateConstantOffset(DL, GEPOffset)) break; - ByteOffset += GEPOffset.getSExtValue(); + APInt OrigByteOffset(ByteOffset); + ByteOffset += GEPOffset.sextOrTrunc(ByteOffset.getBitWidth()); + if (ByteOffset.getMinSignedBits() > 64) { + // Stop traversal if the pointer offset wouldn't fit into int64_t + // (this should be removed if Offset is updated to an APInt) + ByteOffset = OrigByteOffset; + break; + } Ptr = GEP->getPointerOperand(); } else if (Operator::getOpcode(Ptr) == Instruction::BitCast || -- cgit v1.2.3