[llvm] [LLVM][DAGCombiner] Look through freeze when combining extensions of extending-masked-loads. (PR #172484)

[David Sherwood via llvm-commits]

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@@ -7518,27 +7518,23 @@ SDValue DAGCombiner::visitAND(SDNode *N) {
       return N0;
 
     // fold (and (masked_load) (splat_vec (x, ...))) to zext_masked_load
-    auto *MLoad = dyn_cast<MaskedLoadSDNode>(N0);
+    bool Frozen = N0.getOpcode() == ISD::FREEZE;
+    auto *MLoad = dyn_cast<MaskedLoadSDNode>(Frozen ? N0.getOperand(0) : N0);
     ConstantSDNode *Splat = isConstOrConstSplat(N1, true, true);
     if (MLoad && MLoad->getExtensionType() == ISD::EXTLOAD && Splat) {
-      EVT LoadVT = MLoad->getMemoryVT();
-      EVT ExtVT = VT;
-      if (TLI.isLoadExtLegal(ISD::ZEXTLOAD, ExtVT, LoadVT)) {
+      EVT MemVT = MLoad->getMemoryVT();
+      if (TLI.isLoadExtLegal(ISD::ZEXTLOAD, VT, MemVT)) {
         // For this AND to be a zero extension of the masked load the elements
         // of the BuildVec must mask the bottom bits of the extended element
         // type
-        uint64_t ElementSize =
-            LoadVT.getVectorElementType().getScalarSizeInBits();
-        if (Splat->getAPIntValue().isMask(ElementSize)) {
+        if (Splat->getAPIntValue().isMask(MemVT.getScalarSizeInBits())) {
           SDValue NewLoad = DAG.getMaskedLoad(
-              ExtVT, DL, MLoad->getChain(), MLoad->getBasePtr(),
-              MLoad->getOffset(), MLoad->getMask(), MLoad->getPassThru(),
-              LoadVT, MLoad->getMemOperand(), MLoad->getAddressingMode(),
-              ISD::ZEXTLOAD, MLoad->isExpandingLoad());
-          bool LoadHasOtherUsers = !N0.hasOneUse();
-          CombineTo(N, NewLoad);
-          if (LoadHasOtherUsers)
-            CombineTo(MLoad, NewLoad.getValue(0), NewLoad.getValue(1));
+              VT, DL, MLoad->getChain(), MLoad->getBasePtr(),
+              MLoad->getOffset(), MLoad->getMask(), MLoad->getPassThru(), MemVT,
+              MLoad->getMemOperand(), MLoad->getAddressingMode(), ISD::ZEXTLOAD,
+              MLoad->isExpandingLoad());
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david-arm wrote:

Do we need a freeze test for expanding loads too?

https://github.com/llvm/llvm-project/pull/172484