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

[Florian Hahn via llvm-commits]

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@@ -937,10 +938,84 @@ static void recursivelyDeleteDeadRecipes(VPValue *V) {
   }
 }
 
+class VPConstantFolder {
+  TargetFolder Folder;
+  VPTypeAnalysis TypeInfo;
+
+public:
+  VPConstantFolder(const DataLayout &DL, const VPTypeAnalysis &TypeInfo)
+      : Folder(DL), TypeInfo(TypeInfo) {}
+
+  Value *tryToConstantFold(VPRecipeBase &R, unsigned Opcode,
+                           ArrayRef<VPValue *> Operands) {
+    SmallVector<Value *, 4> Ops;
+    for (VPValue *Op : Operands) {
+      if (!Op->isLiveIn() || !Op->getLiveInIRValue())
+        return nullptr;
+      Ops.emplace_back(Op->getLiveInIRValue());
+    }
+    switch (Opcode) {
+    case Instruction::BinaryOps::Add:
+    case Instruction::BinaryOps::Sub:
+    case Instruction::BinaryOps::Mul:
+    case Instruction::BinaryOps::AShr:
+    case Instruction::BinaryOps::LShr:
+    case Instruction::BinaryOps::And:
+    case Instruction::BinaryOps::Or:
+    case Instruction::BinaryOps::Xor:
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fhahn wrote:

Could catch all of those (and possibly more) via `Instruction::isBinaryOp`, same for unary ops.

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