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Add vector versions of some existing scalar transforms to aid codegen in matching psign & pblend operations to the IR produced by clang/gcc for their C idioms.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122105 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nate Begeman
2010-12-17 23:12:19 +00:00
parent 976ef86689
commit 9a3dc55202
3 changed files with 46 additions and 0 deletions
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7
lib/Analysis/ValueTracking.cpp
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@ -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))) {