[libc-commits] [lld] [compiler-rt] [libcxx] [libclc] [lldb] [llvm] [clang-tools-extra] [libc] [libcxxabi] [flang] [clang] [VPlan] Add new VPScalarCastRecipe, use for IV & step trunc. (PR #78113)

[via libc-commits]

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@@ -491,17 +491,39 @@ void VPlanTransforms::removeDeadRecipes(VPlan &Plan) {
 
 static VPValue *createScalarIVSteps(VPlan &Plan, const InductionDescriptor &ID,
                                     ScalarEvolution &SE, Instruction *TruncI,
-                                    Type *IVTy, VPValue *StartV,
-                                    VPValue *Step) {
+                                    VPValue *StartV, VPValue *Step) {
   VPBasicBlock *HeaderVPBB = Plan.getVectorLoopRegion()->getEntryBasicBlock();
   auto IP = HeaderVPBB->getFirstNonPhi();
   VPCanonicalIVPHIRecipe *CanonicalIV = Plan.getCanonicalIV();
-  Type *TruncTy = TruncI ? TruncI->getType() : IVTy;
-  VPValue *BaseIV = CanonicalIV;
-  if (!CanonicalIV->isCanonical(ID.getKind(), StartV, Step, TruncTy)) {
-    BaseIV = new VPDerivedIVRecipe(ID, StartV, CanonicalIV, Step,
-                                   TruncI ? TruncI->getType() : nullptr);
-    HeaderVPBB->insert(BaseIV->getDefiningRecipe(), IP);
+  VPSingleDefRecipe *BaseIV = CanonicalIV;
+  if (!CanonicalIV->isCanonical(ID.getKind(), StartV, Step)) {
+    BaseIV = new VPDerivedIVRecipe(ID, StartV, CanonicalIV, Step);
+    HeaderVPBB->insert(BaseIV, IP);
+  }
+
+  // Truncate base induction if needed.
+  VPTypeAnalysis TypeInfo(SE.getContext());
+  Type *StepTy = TypeInfo.inferScalarType(Step);
----------------
ayalz wrote:

```suggestion
```
Suffice to define StepTy later, when dealing with the truncation of Step. Here we're dealing with truncating BaseIV, and may be good to define its current/original type instead (using "BaseIVTy" may be confusing or deserves updating due to changing BaseIV and its type).

https://github.com/llvm/llvm-project/pull/78113