[llvm] [DAG] Combine `store + vselect` to `masked_store` (PR #145176)
Simon Pilgrim via llvm-commits
llvm-commits at lists.llvm.org
Sat Aug 2 11:07:20 PDT 2025
================
@@ -22515,6 +22515,53 @@ SDValue DAGCombiner::visitATOMIC_STORE(SDNode *N) {
return SDValue();
}
+static SDValue foldToMaskedStore(StoreSDNode *Store, SelectionDAG &DAG,
+ const SDLoc &Dl) {
+ if (!Store->isSimple() || !ISD::isNormalStore(Store))
+ return SDValue();
+
+ SDValue StoredVal = Store->getValue();
+ SDValue StorePtr = Store->getBasePtr();
+ SDValue StoreOffset = Store->getOffset();
+ EVT VT = Store->getMemoryVT();
+ unsigned AddrSpace = Store->getAddressSpace();
+ Align Alignment = Store->getAlign();
+ const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+
+ if (!TLI.isOperationLegalOrCustom(ISD::MSTORE, VT) ||
+ !TLI.allowsMisalignedMemoryAccesses(VT, AddrSpace, Alignment))
+ return SDValue();
+
+ SDValue Mask, OtherVec, LoadCh;
+ unsigned LoadPos;
+ if (sd_match(StoredVal,
+ m_VSelect(m_Value(Mask), m_Value(OtherVec),
+ m_Load(m_Value(LoadCh), m_Specific(StorePtr),
+ m_Specific(StoreOffset))))) {
+ LoadPos = 2;
+ } else if (sd_match(StoredVal,
+ m_VSelect(m_Value(Mask),
+ m_Load(m_Value(LoadCh), m_Specific(StorePtr),
+ m_Specific(StoreOffset)),
+ m_Value(OtherVec)))) {
+ LoadPos = 1;
+ Mask = DAG.getNOT(Dl, Mask, Mask.getValueType());
----------------
RKSimon wrote:
Best not to create nodes if we might still bail out - why not do this just before the getMaskedStore:
```c
if (LoadPos == 1)
Mask = DAG.getNOT(Dl, Mask, Mask.getValueType());
```
https://github.com/llvm/llvm-project/pull/145176
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