diff options
Diffstat (limited to 'lib/Analysis/ScalarEvolution.cpp')
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index 409bad9166..495290d8d7 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -1754,6 +1754,8 @@ SCEVHandle ScalarEvolution::createSCEV(Value *V) { // For an expression like x&255 that merely masks off the high bits, // use zext(trunc(x)) as the SCEV expression. if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) { + if (CI->isNullValue()) + return getSCEV(U->getOperand(1)); const APInt &A = CI->getValue(); unsigned Ones = A.countTrailingOnes(); if (APIntOps::isMask(Ones, A)) @@ -1818,10 +1820,15 @@ SCEVHandle ScalarEvolution::createSCEV(Value *V) { if (Instruction *L = dyn_cast<Instruction>(U->getOperand(0))) if (L->getOpcode() == Instruction::Shl && L->getOperand(1) == U->getOperand(1)) { - uint64_t Amt = getTypeSizeInBits(U->getType()) - CI->getZExtValue(); + unsigned BitWidth = getTypeSizeInBits(U->getType()); + uint64_t Amt = BitWidth - CI->getZExtValue(); + if (Amt == BitWidth) + return getSCEV(L->getOperand(0)); // shift by zero --> noop + if (Amt > BitWidth) + return getIntegerSCEV(0, U->getType()); // value is undefined return getSignExtendExpr(getTruncateExpr(getSCEV(L->getOperand(0)), - IntegerType::get(Amt)), + IntegerType::get(Amt)), U->getType()); } break; |