[llvm] 012523d - [VPlan] Support VPInstruction for intrinsic calls in live-in folding. (#207836)

[via llvm-commits]

Author: Florian Hahn
Date: 2026-07-07T14:43:42Z
New Revision: 012523d96b30a9a6d7148825fe307919a9c4753c

URL: https://github.com/llvm/llvm-project/commit/012523d96b30a9a6d7148825fe307919a9c4753c
DIFF: https://github.com/llvm/llvm-project/commit/012523d96b30a9a6d7148825fe307919a9c4753c.diff

LOG: [VPlan] Support VPInstruction for intrinsic calls in live-in folding. (#207836)

Use getIntrinsicID in getOpcodeOrIntrinsicID. This enables constant
folding for VPInstructions calling intrinsics.

PR: https://github.com/llvm/llvm-project/pull/207836

Added: 
    

Modified: 
    llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
    llvm/test/Transforms/LoopVectorize/VPlan/constant-fold.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 39e8ae5dd3b8c..0a879d7d92941 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -1249,14 +1249,13 @@ static void recursivelyDeleteDeadRecipes(VPValue *V) {
 /// an intrinsic ID.
 static std::optional<std::pair<bool, unsigned>>
 getOpcodeOrIntrinsicID(const VPSingleDefRecipe *R) {
+  if (Intrinsic::ID IID = vputils::getIntrinsicID(R))
+    return std::make_pair(true, IID);
   return TypeSwitch<const VPSingleDefRecipe *,
                     std::optional<std::pair<bool, unsigned>>>(R)
       .Case<VPInstruction, VPWidenRecipe, VPWidenCastRecipe, VPWidenGEPRecipe,
             VPReplicateRecipe>(
           [](auto *I) { return std::make_pair(false, I->getOpcode()); })
-      .Case([](const VPWidenIntrinsicRecipe *I) {
-        return std::make_pair(true, I->getVectorIntrinsicID());
-      })
       .Case<VPVectorPointerRecipe, VPPredInstPHIRecipe, VPScalarIVStepsRecipe>(
           [](auto *I) {
             // For recipes that do not directly map to LLVM IR instructions,
@@ -1294,6 +1293,10 @@ static VPIRValue *tryToFoldLiveIns(VPSingleDefRecipe &R,
   auto FoldToIRValue = [&]() -> Value * {
     InstSimplifyFolder Folder(DL);
     if (OpcodeOrIID->first) {
+      // VPInstructions store the called intrinsic as last operand.
+      if (isa<VPInstruction>(R))
+        Ops.pop_back();
+
       auto *RFlags = dyn_cast<VPRecipeWithIRFlags>(&R);
       return Folder.FoldIntrinsic(OpcodeOrIID->second, Ops, R.getScalarType(),
                                   RFlags ? RFlags->getFastMathFlagsOrNone()

diff  --git a/llvm/test/Transforms/LoopVectorize/VPlan/constant-fold.ll b/llvm/test/Transforms/LoopVectorize/VPlan/constant-fold.ll
index 450dd75332f92..92bb9704c4fd2 100644
--- a/llvm/test/Transforms/LoopVectorize/VPlan/constant-fold.ll
+++ b/llvm/test/Transforms/LoopVectorize/VPlan/constant-fold.ll
@@ -282,7 +282,7 @@ define void @fold_replicating_umax_equal_live_ins(ptr noalias %dst, ptr %cond, i
 ; CHECK-NEXT:  then:
 ; CHECK-NEXT:    EMIT ir<%m> = call ir<%x>, ir<%x>, ir<@llvm.umax.i32>
 ; CHECK-NEXT:    EMIT ir<%gep> = getelementptr ir<%dst>, ir<%iv>
-; CHECK-NEXT:    EMIT store ir<%m>, ir<%gep>
+; CHECK-NEXT:    EMIT store ir<%x>, ir<%gep>
 ; CHECK-NEXT:  Successor(s): latch
 ; CHECK-EMPTY:
 ; CHECK-NEXT:  latch: