[llvm] [VPlan] Impl VPlan-based pattern match for ExtendedRed and MulAccRed (NFCI) (PR #113903)

[Alexey Bataev via llvm-commits]

================
@@ -1851,6 +1859,88 @@ void VPlanTransforms::createInterleaveGroups(
   }
 }
 
+// Expand VPExtendedReductionRecipe to VPWidenCastRecipe + VPReductionRecipe.
+static void expandVPExtendedReduction(VPExtendedReductionRecipe *ExtRed) {
+  // Genearte VPWidenCastRecipe.
+  VPWidenCastRecipe *Ext;
+  // Only ZExt contiains non-neg flags.
+  if (ExtRed->isZExt())
+    Ext = new VPWidenCastRecipe(ExtRed->getExtOpcode(), ExtRed->getVecOp(),
+                                ExtRed->getResultType(), ExtRed->isNonNeg(),
+                                ExtRed->getExtDebugLoc());
+  else
+    Ext = new VPWidenCastRecipe(ExtRed->getExtOpcode(), ExtRed->getVecOp(),
+                                ExtRed->getResultType(),
+                                ExtRed->getExtDebugLoc());
+
+  // Generate VPreductionRecipe.
+  auto *Red = new VPReductionRecipe(
+      ExtRed->getRecurrenceDescriptor(), ExtRed->getChainOp(), Ext,
+      ExtRed->getCondOp(), ExtRed->isOrdered(), ExtRed->getRedDebugLoc());
+  Ext->insertBefore(ExtRed);
+  Red->insertBefore(ExtRed);
+  ExtRed->replaceAllUsesWith(Red);
+  ExtRed->eraseFromParent();
+}
+
+// Expand VPMulAccumulateReductionRecipe to VPWidenRecipe (mul) +
+// VPReductionRecipe (reduce.add)
+// + VPWidenCastRecipe (optional).
+static void
+expandVPMulAccumulateReduction(VPMulAccumulateReductionRecipe *MulAcc) {
+  Type *RedTy = MulAcc->getRecurrenceDescriptor().getRecurrenceType();
+
+  // Generate inner VPWidenCastRecipes if necessary.
+  // Note that we will drop the extend after mul which transform
+  // reduce.add(ext(mul(ext, ext))) to reduce.add(mul(ext, ext)).
+  VPValue *Op0, *Op1;
+  if (MulAcc->isExtended()) {
+    if (MulAcc->isZExt())
+      Op0 = new VPWidenCastRecipe(MulAcc->getExtOpcode(), MulAcc->getVecOp0(),
+                                  RedTy, MulAcc->isNonNeg(),
+                                  MulAcc->getExt0DebugLoc());
+    else
+      Op0 = new VPWidenCastRecipe(MulAcc->getExtOpcode(), MulAcc->getVecOp0(),
+                                  RedTy, MulAcc->getExt0DebugLoc());
+    Op0->getDefiningRecipe()->insertBefore(MulAcc);
+    // Prevent reduce.add(mul(ext(A), ext(A))) generate duplicate
+    // VPWidenCastRecipe.
+    if (MulAcc->getVecOp0() == MulAcc->getVecOp1()) {
+      Op1 = Op0;
+    } else {
+      if (MulAcc->isZExt())
----------------
alexey-bataev wrote:

```suggestion
    } else if (MulAcc->isZExt())
```


https://github.com/llvm/llvm-project/pull/113903