[llvm] [PowerPC] Fix vector_shuffle combines when inputs are scalar_to_vector of differing types. (PR #80784)

[Maryam Moghadas via llvm-commits]

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@@ -15519,33 +15556,33 @@ SDValue PPCTargetLowering::combineVectorShuffle(ShuffleVectorSDNode *SVN,
     // the value into element zero. Since scalar size of LHS and RHS may differ
     // after isScalarToVec, this should be checked using their own sizes.
     if (SToVLHS) {
-      if (!IsLittleEndian && SToVLHS.getValueType().getScalarSizeInBits() >= 64)
+      int LHSScalarSize = SToVLHS.getValueType().getScalarSizeInBits();
+      if (!IsLittleEndian && LHSScalarSize >= 64)
         return Res;
-      // Set up the values for the shuffle vector fixup.
-      LHSMaxIdx = NumEltsOut / NumEltsIn;
-      SToVLHS = getSToVPermuted(SToVLHS, DAG, Subtarget);
-      if (SToVLHS.getValueType() != LHS.getValueType())
-        SToVLHS = DAG.getBitcast(LHS.getValueType(), SToVLHS);
-      LHS = SToVLHS;
+      LHS = generateSToVPermutedForVecShuffle(
+          LHSScalarSize, ShuffleEltWidth, LHSNumValidElts, LHSFirstElt,
+          LHSLastElt, LHS, SToVLHS, DAG, Subtarget);
     }
     if (SToVRHS) {
-      if (!IsLittleEndian && SToVRHS.getValueType().getScalarSizeInBits() >= 64)
+      int RHSScalarSize = SToVRHS.getValueType().getScalarSizeInBits();
+      if (!IsLittleEndian && RHSScalarSize >= 64)
         return Res;
-      RHSMinIdx = NumEltsOut;
-      RHSMaxIdx = NumEltsOut / NumEltsIn + RHSMinIdx;
-      SToVRHS = getSToVPermuted(SToVRHS, DAG, Subtarget);
-      if (SToVRHS.getValueType() != RHS.getValueType())
-        SToVRHS = DAG.getBitcast(RHS.getValueType(), SToVRHS);
-      RHS = SToVRHS;
+      RHS = generateSToVPermutedForVecShuffle(
+          RHSScalarSize, ShuffleEltWidth, RHSNumValidElts, RHSFirstElt,
+          RHSLastElt, RHS, SToVRHS, DAG, Subtarget);
     }
 
+    if (!isShuffleMaskInRange(ShuffV, HalfVec, LHSLastElt, RHSLastElt))
+      return Res;
+
     // Fix up the shuffle mask to reflect where the desired element actually is.
     // The minimum and maximum indices that correspond to element zero for both
     // the LHS and RHS are computed and will control which shuffle mask entries
     // are to be changed. For example, if the RHS is permuted, any shuffle mask
-    // entries in the range [RHSMinIdx,RHSMaxIdx) will be adjusted.
-    fixupShuffleMaskForPermutedSToV(ShuffV, LHSMaxIdx, RHSMinIdx, RHSMaxIdx,
-                                    HalfVec, ValidLaneWidth, Subtarget);
+    // entries in the range [RHSFirstElt,RHSLastElt] will be adjusted.
+    fixupShuffleMaskForPermutedSToV(
+        ShuffV, LHSFirstElt, LHSLastElt, RHSFirstElt, RHSLastElt, HalfVec,
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maryammo wrote:

same question about LHSFirstElt?

https://github.com/llvm/llvm-project/pull/80784