[llvm] [VPlan] Support live-ins without underlying IR in type analysis. (PR #80723)

[via llvm-commits]

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@@ -203,6 +198,16 @@ Type *VPTypeAnalysis::inferScalarTypeForRecipe(const VPReplicateRecipe *R) {
   llvm_unreachable("Unhandled opcode");
 }
 
+VPTypeAnalysis::VPTypeAnalysis(VPlan &Plan, LLVMContext &Ctx) : Ctx(Ctx) {
+  auto *CanIV = Plan.getCanonicalIV();
+  Type *CanIVTy = inferScalarType(CanIV);
+  CachedTypes[&Plan.getVectorTripCount()] = CanIVTy;
+  CachedTypes[&Plan.getVFxUF()] = CanIVTy;
+  CachedTypes[Plan.getTripCount()] = CanIVTy;
+  if (auto *BTC = Plan.getBackedgeTakenCount())
+    CachedTypes[BTC] = CanIVTy;
+}
+
 Type *VPTypeAnalysis::inferScalarType(const VPValue *V) {
   if (Type *CachedTy = CachedTypes.lookup(V))
     return CachedTy;
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ayalz wrote:

An alternative to caching the pre-computed type for all live-ins-w/o-underlying-value, as raised above, may be to change below into:

```
  if (V->isLiveIn()) {
    if (auto *IRValue = V->getLiveInIRValue())
      return IRValue->getType();
    return CanonicalType;
  }
```

https://github.com/llvm/llvm-project/pull/80723