[llvm] [VPlan] Add initial anlysis to infer scalar type of VPValues. (PR #69013)

[via llvm-commits]

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@@ -1458,7 +1460,7 @@ class VPWidenIntOrFpInductionRecipe : public VPHeaderPHIRecipe {
   bool isCanonical() const;
 
   /// Returns the scalar type of the induction.
-  const Type *getScalarType() const {
+  Type *getScalarType() const {
     return Trunc ? Trunc->getType() : IV->getType();
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ayalz wrote:

Can wait for separate subsequent patch: type of all header phi's should arguably be derived from their start value. If it gets truncated, let the start value be truncated in VPlan. Similar for DerivedIV.

https://github.com/llvm/llvm-project/pull/69013