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[SDAG] Handle non-integer preferred memset types for non-constant values

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The existing code in getMemsetValue only handled integer-preferred types when
the fill value was not a constant. Make this more robust in two ways:

  1. If the preferred type is a floating-point value, do the mul-splat trick on
     the corresponding integer type and then bitcast.
  2. If the preferred type is a vector, do the mul-splat trick on one vector
     element, and then build a vector out of them.

Fixes PR22754 (although, we should also turn off use of vector types at -O0).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233749 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel
2015-03-31 20:35:26 +00:00
parent 83b5f345b2
commit 20fc6ac99e
3 changed files with 80 additions and 2 deletions
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19
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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@ -3791,12 +3791,27 @@ static SDValue getMemsetValue(SDValue Value, EVT VT, SelectionDAG &DAG,
return DAG.getConstantFP(APFloat(DAG.EVTToAPFloatSemantics(VT), Val), VT);
}
Value = DAG.getNode(ISD::ZERO_EXTEND, dl, VT, Value);
assert(Value.getValueType() == MVT::i8 && "memset with non-byte fill value?");
EVT IntVT = VT.getScalarType();
if (!IntVT.isInteger())
IntVT = EVT::getIntegerVT(*DAG.getContext(), IntVT.getSizeInBits());
Value = DAG.getNode(ISD::ZERO_EXTEND, dl, IntVT, Value);
if (NumBits > 8) {
// Use a multiplication with 0x010101... to extend the input to the
// required length.
APInt Magic = APInt::getSplat(NumBits, APInt(8, 0x01));
Value = DAG.getNode(ISD::MUL, dl, VT, Value, DAG.getConstant(Magic, VT));
Value = DAG.getNode(ISD::MUL, dl, IntVT, Value,
DAG.getConstant(Magic, IntVT));
}
if (VT != Value.getValueType() && !VT.isInteger())
Value = DAG.getNode(ISD::BITCAST, dl, VT.getScalarType(), Value);
if (VT != Value.getValueType()) {
assert(VT.getVectorElementType() == Value.getValueType() &&
"value type should be one vector element here");
SmallVector<SDValue, 8> BVOps(VT.getVectorNumElements(), Value);
Value = DAG.getNode(ISD::BUILD_VECTOR, dl, VT, BVOps);
}
return Value;