[llvm] [VPlan] Explicitly handle scalar pointer inductions. (PR #83068)

[via llvm-commits]

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@@ -511,17 +550,33 @@ void VPInstruction::execute(VPTransformState &State) {
          "Recipe not a FPMathOp but has fast-math flags?");
   if (hasFastMathFlags())
     State.Builder.setFastMathFlags(getFastMathFlags());
+  State.Builder.SetCurrentDebugLocation(getDebugLoc());
+  bool OnlyGenerateFirstLane =
+      canGenerateScalarForFirstLane() &&
+      (vputils::onlyFirstLaneUsed(this) ||
+       getOpcode() == VPInstruction::ComputeReductionResult);
+  bool GeneratesPerAllLanes = doesGeneratePerAllLanes();
   for (unsigned Part = 0; Part < State.UF; ++Part) {
-    Value *GeneratedValue = generateInstruction(State, Part);
+    if (GeneratesPerAllLanes) {
+      for (unsigned Lane = 0, NumLanes = State.VF.getKnownMinValue();
+           Lane != NumLanes; ++Lane) {
+        Value *P = generatePerLane(State, VPIteration(Part, Lane));
+        State.set(this, P, VPIteration(Part, Lane));
+      }
+      continue;
+    }
+
+    Value *GeneratedValue = OnlyGenerateFirstLane
+                                ? generatePerLane(State, VPIteration(Part, 0))
+                                : generatePerPart(State, Part);
     if (!hasResult())
       continue;
     assert(GeneratedValue && "generateInstruction must produce a value");
 
-    bool IsVector = GeneratedValue->getType()->isVectorTy();
-    State.set(this, GeneratedValue, Part, !IsVector);
-    assert((IsVector || getOpcode() == VPInstruction::ComputeReductionResult ||
-            State.VF.isScalar() || vputils::onlyFirstLaneUsed(this)) &&
-           "scalar value but not only first lane used");
+    State.set(this, GeneratedValue, Part, /*IsScalar*/ OnlyGenerateFirstLane);
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ayalz wrote:

nit: better to set State after the following assert.

https://github.com/llvm/llvm-project/pull/83068