[llvm] [VPlan] Introduce VPlan-level constant folder (PR #125365)

[Florian Hahn via llvm-commits]

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@@ -563,29 +563,24 @@ define void @pr70590_recipe_without_underlying_instr(i64 %n, ptr noalias %dst) {
 ; CHECK-NEXT:    [[TMP3:%.*]] = extractelement <4 x i1> [[TMP2]], i32 0
 ; CHECK-NEXT:    br i1 [[TMP3]], label [[PRED_SREM_IF:%.*]], label [[PRED_SREM_CONTINUE:%.*]]
 ; CHECK:       pred.srem.if:
-; CHECK-NEXT:    [[TMP4:%.*]] = srem i64 3, 0
 ; CHECK-NEXT:    br label [[PRED_SREM_CONTINUE]]
 ; CHECK:       pred.srem.continue:
-; CHECK-NEXT:    [[TMP5:%.*]] = phi i64 [ poison, %vector.body ], [ [[TMP4]], [[PRED_SREM_IF]] ]
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fhahn wrote:

Yep, that would need to extra code to handle `PredPhi poison -> poison`. If that would be enough to remove the need to change `VPPredInstPHIRecipe::execute(` and. `VPTransformState::` that would be desireable.

https://github.com/llvm/llvm-project/pull/125365