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[DAGCombine] Pull out repeated demanded bitmask generation. NFCI. 

llvm-svn: 355932
This commit is contained in:
Simon Pilgrim 2019-03-12 15:58:28 +00:00
parent 02e88490c1
commit 9f0a5ca843
1 changed files with 9 additions and 10 deletions
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19
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -15420,23 +15420,22 @@ SDValue DAGCombiner::visitSTORE(SDNode *N) {
Value.getValueType().isInteger() &&
(!isa<ConstantSDNode>(Value) ||
!cast<ConstantSDNode>(Value)->isOpaque())) {
APInt TruncDemandedBits =
APInt::getLowBitsSet(Value.getScalarValueSizeInBits(),
ST->getMemoryVT().getScalarSizeInBits());
// See if we can simplify the input to this truncstore with knowledge that
// only the low bits are being used. For example:
// "truncstore (or (shl x, 8), y), i8" -> "truncstore y, i8"
SDValue Shorter = DAG.GetDemandedBits(
Value, APInt::getLowBitsSet(Value.getScalarValueSizeInBits(),
ST->getMemoryVT().getScalarSizeInBits()));
SDValue Shorter = DAG.GetDemandedBits(Value, TruncDemandedBits);
AddToWorklist(Value.getNode());
if (Shorter.getNode())
return DAG.getTruncStore(Chain, SDLoc(N), Shorter,
Ptr, ST->getMemoryVT(), ST->getMemOperand());
if (Shorter)
return DAG.getTruncStore(Chain, SDLoc(N), Shorter, Ptr, ST->getMemoryVT(),
ST->getMemOperand());
// Otherwise, see if we can simplify the operation with
// SimplifyDemandedBits, which only works if the value has a single use.
if (SimplifyDemandedBits(
Value,
APInt::getLowBitsSet(Value.getScalarValueSizeInBits(),
ST->getMemoryVT().getScalarSizeInBits()))) {
if (SimplifyDemandedBits(Value, TruncDemandedBits)) {
// Re-visit the store if anything changed and the store hasn't been merged
// with another node (N is deleted) SimplifyDemandedBits will add Value's
// node back to the worklist if necessary, but we also need to re-visit