[llvm] [VPlan] Introduce VPlanConstantFolder (PR #125365)

[Ramkumar Ramachandra via llvm-commits]

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@@ -180,31 +186,45 @@ class VPBuilder {
 
   VPValue *createNot(VPValue *Operand, DebugLoc DL = {},
                      const Twine &Name = "") {
+    if (auto *V = Folder.foldNot(Operand))
+      if (BB)
+        return getOrAddLiveIn(V);
     return createInstruction(VPInstruction::Not, {Operand}, DL, Name);
   }
 
   VPValue *createAnd(VPValue *LHS, VPValue *RHS, DebugLoc DL = {},
                      const Twine &Name = "") {
+    if (auto *V = Folder.foldAnd(LHS, RHS))
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artagnon wrote:

I thought about this, but I fear we'll have to match the VPInstruction using a switch, and dispatch appropriately: not sure if this is preferable, so let's keep this thread open.

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