[PATCH] D122703: [AArch64][InstCombine] Fold MLOAD and zero extensions into MLOAD

[Allen zhong via Phabricator via llvm-commits]

Allen created this revision.
Allen added reviewers: paulwalker-arm, david-arm, fhahn, craig.topper.
Herald added subscribers: StephenFan, hiraditya, kristof.beyls.
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Accord the discussion in D122281 <https://reviews.llvm.org/D122281>, we missing an ISD::AND combine for MLOAD.
This patch is intend to handle that, so we can circle back the type MVT::nxv2i32


https://reviews.llvm.org/D122703

Files:
  llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
  llvm/test/CodeGen/AArch64/sve-masked-ldst-zext.ll


Index: llvm/test/CodeGen/AArch64/sve-masked-ldst-zext.ll
===================================================================
--- llvm/test/CodeGen/AArch64/sve-masked-ldst-zext.ll
+++ llvm/test/CodeGen/AArch64/sve-masked-ldst-zext.ll
@@ -97,7 +97,7 @@
 ; CHECK-LABEL: masked_zload_2i16_2f64:
 ; CHECK:       ld1h { z0.d }, p0/z, [x0]
 ; CHECK-NEXT:  ptrue p0.d
-; CHECK-NEXT:  ucvtf z0.d, p0/m, z0.s
+; CHECK-NEXT:  ucvtf z0.d, p0/m, z0.d
 ; CHECK-NEXT:  ret
   %wide.load = call <vscale x 2 x i16> @llvm.masked.load.nxv2i16(<vscale x 2 x i16>* %in, i32 2, <vscale x 2 x i1> %mask, <vscale x 2 x i16> undef)
   %zext = zext <vscale x 2 x i16> %wide.load to <vscale x 2 x i32>
Index: llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -1247,7 +1247,6 @@
       setLoadExtAction(Op, MVT::nxv2i64, MVT::nxv2i16, Legal);
       setLoadExtAction(Op, MVT::nxv2i64, MVT::nxv2i32, Legal);
       setLoadExtAction(Op, MVT::nxv4i32, MVT::nxv4i8, Legal);
-      setLoadExtAction(Op, MVT::nxv2i32, MVT::nxv2i16, Legal);
       setLoadExtAction(Op, MVT::nxv4i32, MVT::nxv4i16, Legal);
       setLoadExtAction(Op, MVT::nxv8i16, MVT::nxv8i8, Legal);
     }
@@ -14405,6 +14404,30 @@
 
   EVT MemVT;
 
+  // Zero/any extend of an MLOAD
+  if (const MaskedLoadSDNode *MLd = dyn_cast<MaskedLoadSDNode>(Src)) {
+    MemVT = MLd->getMemoryVT();
+    MVT::SimpleValueType Ty = MemVT.getSimpleVT().SimpleTy;
+    SDValue Dup = N->getOperand(1);
+    if (Dup.getOpcode() != AArch64ISD::DUP)
+      return SDValue();
+
+    SDLoc DL(N);
+    ConstantSDNode *C = dyn_cast<ConstantSDNode>(Dup->getOperand(0));
+    if (!C)
+      return SDValue();
+
+    uint64_t ExtVal = C->getZExtValue();
+
+    // If the mask is fully covered by the MLOAD, we don't need to push
+    // a new AND onto the operand
+    EVT EltTy = MemVT.getVectorElementType();
+    if ((ExtVal == 0xFF && EltTy == MVT::i8) ||
+        (ExtVal == 0xFFFF && EltTy == MVT::i16) ||
+        (ExtVal == 0xFFFFFFFF && EltTy == MVT::i32))
+      return Src;
+  }
+
   // SVE load instructions perform an implicit zero-extend, which makes them
   // perfect candidates for combining.
   switch (Opc) {


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