[llvm] [VPlan] Extend tryToFoldLiveIns to fold binary intrinsics (PR #161703)

[Florian Hahn via llvm-commits]

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@@ -943,12 +943,39 @@ static void recursivelyDeleteDeadRecipes(VPValue *V) {
   }
 }
 
+/// Get any instruction opcode or intrinsic ID data embedded in recipe \p R.
+/// Returns an optional pair, where the first element indicates whether it is
+/// an intrinsic ID.
+static std::optional<std::pair<bool, unsigned>>
+getOpcodeOrIntrinsicID(const VPSingleDefRecipe *R) {
+  return TypeSwitch<const VPSingleDefRecipe *,
+                    std::optional<std::pair<bool, unsigned>>>(R)
+      .Case<VPInstruction, VPWidenRecipe, VPWidenCastRecipe,
+            VPWidenSelectRecipe, VPWidenGEPRecipe, VPReplicateRecipe>(
+          [](auto *I) { return std::make_pair(false, I->getOpcode()); })
+      .Case<VPWidenIntrinsicRecipe>([](auto *I) {
+        return std::make_pair(true, I->getVectorIntrinsicID());
+      })
+      .Case<VPVectorPointerRecipe, VPPredInstPHIRecipe>([](auto *I) {
+        // For recipes that do not directly map to LLVM IR instructions,
+        // assign opcodes after the last VPInstruction opcode (which is also
+        // after the last IR Instruction opcode), based on the VPDefID.
+        return std::make_pair(false,
+                              VPInstruction::OpsEnd + 1 + I->getVPDefID());
+      })
+      .Default([](auto *) { return std::nullopt; });
+}
+
 /// Try to fold \p R using InstSimplifyFolder. Will succeed and return a
-/// non-nullptr Value for a handled \p Opcode if corresponding \p Operands are
-/// foldable live-ins.
-static Value *tryToFoldLiveIns(const VPRecipeBase &R, unsigned Opcode,
+/// non-nullptr Value for a handled opcode or intrinsic ID if corresponding \p
+/// Operands are foldable live-ins.
+static Value *tryToFoldLiveIns(VPSingleDefRecipe &R,
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fhahn wrote:

while you are updatig this, it might be cleaner to return a VPValue *here? Should be easy to retrieve Plan from `R`?

https://github.com/llvm/llvm-project/pull/161703