[llvm] [VectorCombine] Add foldShuffleOfIntrinsics. (PR #106502)

[Simon Pilgrim via llvm-commits]

================
@@ -1673,6 +1674,89 @@ bool VectorCombine::foldShuffleOfShuffles(Instruction &I) {
   return true;
 }
 
+/// Try to convert
+/// "shuffle (intrinsic), (intrinsic)" into "intrinsic (shuffle), (shuffle)".
+bool VectorCombine::foldShuffleOfIntrinsics(Instruction &I) {
+  Value *V0, *V1;
+  ArrayRef<int> OldMask;
+  if (!match(&I, m_Shuffle(m_OneUse(m_Value(V0)), m_OneUse(m_Value(V1)),
+                           m_Mask(OldMask))))
+    return false;
+
+  auto *II0 = dyn_cast<IntrinsicInst>(V0);
+  auto *II1 = dyn_cast<IntrinsicInst>(V1);
+  if (!II0 || !II1)
+    return false;
+
+  Intrinsic::ID IID = II0->getIntrinsicID();
+  if (IID != II1->getIntrinsicID())
+    return false;
+
+  auto *ShuffleDstTy = dyn_cast<FixedVectorType>(I.getType());
+  auto *II0Ty = dyn_cast<FixedVectorType>(II0->getType());
+  if (!ShuffleDstTy || !II0Ty)
+    return false;
+
+  if (!isTriviallyVectorizable(IID))
+    return false;
+
+  for (unsigned I = 0; I != II0->arg_size(); ++I)
----------------
RKSimon wrote:

(style) `for (unsigned I = 0, E = II0->arg_size(); I != E; ++I)`

https://github.com/llvm/llvm-project/pull/106502