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[InstCombine][X86] MULDQ/MULUDQ undef -> zero 

Added early out for single undef input - we were already supporting (and testing) this in the constant folding code, we just do it quicker now

Drop undef handling from demanded elts code now that we handle it fully in InstCombiner::visitCallInst

llvm-svn: 292913
This commit is contained in:
Simon Pilgrim 2017-01-24 11:07:41 +00:00
parent f726dfa65e
commit 78f8630ac0
2 changed files with 1 additions and 7 deletions
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2
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
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@ -520,7 +520,7 @@ static Value *simplifyX86muldq(const IntrinsicInst &II,
ResTy->getScalarSizeInBits() == 64 && "Unexpected muldq/muludq types"); ResTy->getScalarSizeInBits() == 64 && "Unexpected muldq/muludq types");
// muldq/muludq(undef, undef) -> zero (matches generic mul behavior) // muldq/muludq(undef, undef) -> zero (matches generic mul behavior)
if (isa<UndefValue>(Arg0) && isa<UndefValue>(Arg1)) if (isa<UndefValue>(Arg0) || isa<UndefValue>(Arg1))
return ConstantAggregateZero::get(ResTy); return ConstantAggregateZero::get(ResTy);
// Constant folding. // Constant folding.

6
llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
View File

@ -1469,12 +1469,6 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
Depth + 1); Depth + 1);
if (TmpV) { II->setArgOperand(1, TmpV); MadeChange = true; } if (TmpV) { II->setArgOperand(1, TmpV); MadeChange = true; }
// Output elements are undefined if both are undefined. Consider things
// like undef*0. The result is known zero, not undef.
for (unsigned i = 0; i != VWidth; ++i)
if (UndefElts2[i * 2] && UndefElts3[i * 2])
UndefElts.setBit(i);
break; break;
} }