diff options
| -rw-r--r-- | lib/Analysis/CaptureTracking.cpp | 25 |
1 files changed, 19 insertions, 6 deletions
diff --git a/lib/Analysis/CaptureTracking.cpp b/lib/Analysis/CaptureTracking.cpp index 9f27e3dd18..e86ad96e4a 100644 --- a/lib/Analysis/CaptureTracking.cpp +++ b/lib/Analysis/CaptureTracking.cpp @@ -19,6 +19,7 @@ #include "llvm/Analysis/CaptureTracking.h" #include "llvm/Instructions.h" #include "llvm/Value.h" +#include "llvm/Analysis/AliasAnalysis.h" #include "llvm/ADT/SmallSet.h" #include "llvm/ADT/SmallVector.h" #include "llvm/Support/CallSite.h" @@ -104,13 +105,25 @@ bool llvm::PointerMayBeCaptured(const Value *V, Worklist.push_back(U); } break; - case Instruction::ICmp: - // Comparing the pointer against null does not count as a capture. - if (ConstantPointerNull *CPN = - dyn_cast<ConstantPointerNull>(I->getOperand(1))) - if (CPN->getType()->getAddressSpace() == 0) - break; + case Instruction::ICmp: { + // Don't count comparisons of the original value against null as captures. + // This allows us to ignore comparisons of malloc results with null, + // for example. + if (isIdentifiedObject(V)) + if (ConstantPointerNull *CPN = + dyn_cast<ConstantPointerNull>(I->getOperand(1))) + if (CPN->getType()->getAddressSpace() == 0) + break; + // Don't count comparisons of two pointers within the same identified + // object as captures. + Value *O0 = I->getOperand(0)->getUnderlyingObject(); + if (isIdentifiedObject(O0) && + O0 == I->getOperand(1)->getUnderlyingObject()) + break; + // Otherwise, be conservative. There are crazy ways to capture pointers + // using comparisons. return true; + } default: // Something else - be conservative and say it is captured. return true; |