diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index d615c752b0..4462986f15 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -1742,12 +1742,14 @@ SCEVHandle ScalarEvolutionsImpl::createSCEV(Value *V) { } break; case Instruction::Xor: - // If the RHS of the xor is a signbit, then this is just an add. - // Instcombine turns add of signbit into xor as a strength reduction step. if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) { + // If the RHS of the xor is a signbit, then this is just an add. + // Instcombine turns add of signbit into xor as a strength reduction step. if (CI->getValue().isSignBit()) return SE.getAddExpr(getSCEV(U->getOperand(0)), getSCEV(U->getOperand(1))); + + // If the RHS of xor is -1, then this is a not operation. else if (CI->isAllOnesValue()) return SE.getNotSCEV(getSCEV(U->getOperand(0))); } @@ -1763,6 +1765,16 @@ SCEVHandle ScalarEvolutionsImpl::createSCEV(Value *V) { } break; + case Instruction::LShr: + // Turn logical shift right of a constant into a unsigned divide. + if (ConstantInt *SA = dyn_cast<ConstantInt>(U->getOperand(1))) { + uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth(); + Constant *X = ConstantInt::get( + APInt(BitWidth, 1).shl(SA->getLimitedValue(BitWidth))); + return SE.getUDivExpr(getSCEV(U->getOperand(0)), getSCEV(X)); + } + break; + case Instruction::Trunc: return SE.getTruncateExpr(getSCEV(U->getOperand(0)), U->getType()); |