diff options
Diffstat (limited to 'lib/Analysis/ValueTracking.cpp')
| -rw-r--r-- | lib/Analysis/ValueTracking.cpp | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp index 75062953cb..f8145cd0e3 100644 --- a/lib/Analysis/ValueTracking.cpp +++ b/lib/Analysis/ValueTracking.cpp @@ -678,6 +678,13 @@ unsigned llvm::ComputeNumSignBits(Value *V, const TargetData *TD, Tmp += C->getZExtValue(); if (Tmp > TyBits) Tmp = TyBits; } + // vector ashr X, <C, C, C, C> -> adds C sign bits + if (ConstantVector *C = dyn_cast<ConstantVector>(U->getOperand(1))) { + if (ConstantInt *CI = dyn_cast_or_null<ConstantInt>(C->getSplatValue())) { + Tmp += CI->getZExtValue(); + if (Tmp > TyBits) Tmp = TyBits; + } + } return Tmp; case Instruction::Shl: if (ConstantInt *C = dyn_cast<ConstantInt>(U->getOperand(1))) { |