Commit d6dff71d authored by Hans Wennborg's avatar Hans Wennborg
Browse files

Merging r276510: 

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r276510 | majnemer | 2016-07-22 19:56:49 -0700 (Fri, 22 Jul 2016) | 9 lines

[LoopUnrollAnalyzer] Handle out of bounds accesses in visitLoad

While we handed loads past the end of an array, we didn't handle loads
_before_ the array.

This fixes PR28062.

N.B. While the bug in the code is obvious, I am struggling to craft a
test case which is reasonable in size.
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llvm-svn: 276688
parent 5244f2f9

llvm/lib/Analysis/LoopUnrollAnalyzer.cpp

+10 −4
Original line number Diff line number Diff line
@@ -118,10 +118,16 @@ bool UnrolledInstAnalyzer::visitLoad(LoadInst &I) { 
  if (CDS->getElementType() != I.getType())

    return false;



  int ElemSize = CDS->getElementType()->getPrimitiveSizeInBits() / 8U;

  if (SimplifiedAddrOp->getValue().getActiveBits() >= 64)

  unsigned ElemSize = CDS->getElementType()->getPrimitiveSizeInBits() / 8U;

  if (SimplifiedAddrOp->getValue().getActiveBits() > 64)

    return false;

  int64_t Index = SimplifiedAddrOp->getSExtValue() / ElemSize;

  int64_t SimplifiedAddrOpV = SimplifiedAddrOp->getSExtValue();

  if (SimplifiedAddrOpV < 0) {

    // FIXME: For now we conservatively ignore out of bound accesses, but

    // we're allowed to perform the optimization in this case.

    return false;

  }

  uint64_t Index = static_cast<uint64_t>(SimplifiedAddrOpV) / ElemSize;

  if (Index >= CDS->getNumElements()) {

    // FIXME: For now we conservatively ignore out of bound accesses, but

    // we're allowed to perform the optimization in this case.