[llvm] r276510 - [LoopUnrollAnalyzer] Handle out of bounds accesses in visitLoad
David Majnemer via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 22 19:56:49 PDT 2016
Author: majnemer
Date: Fri Jul 22 21:56:49 2016
New Revision: 276510
URL: http://llvm.org/viewvc/llvm-project?rev=276510&view=rev
Log:
[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.
Modified:
llvm/trunk/lib/Analysis/LoopUnrollAnalyzer.cpp
Modified: llvm/trunk/lib/Analysis/LoopUnrollAnalyzer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/LoopUnrollAnalyzer.cpp?rev=276510&r1=276509&r2=276510&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/LoopUnrollAnalyzer.cpp (original)
+++ llvm/trunk/lib/Analysis/LoopUnrollAnalyzer.cpp Fri Jul 22 21:56:49 2016
@@ -115,13 +115,19 @@ bool UnrolledInstAnalyzer::visitLoad(Loa
// We might have a vector load from an array. FIXME: for now we just bail
// out in this case, but we should be able to resolve and simplify such
// loads.
- if(CDS->getElementType() != I.getType())
+ 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.
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