[llvm] [VPlan] Verify VPIRFlags when creating VPWidenRecipe. (PR #213039)

[Florian Hahn via llvm-commits]

https://github.com/fhahn created https://github.com/llvm/llvm-project/pull/213039

VPWidenRecipe's constructor didn't check its flags at all, unlike VPInstruction and VPWidenCastRecipe. Add checks and fix remaining violations.

>From 00f14d625324403a321625f04ea1e9f6cfc73b94 Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Thu, 30 Jul 2026 14:02:09 +0100
Subject: [PATCH] [VPlan] Verify VPIRFlags when creating VPWidenRecipe.

VPWidenRecipe's constructor didn't check its flags at all, unlike
VPInstruction and VPWidenCastRecipe. Add checks and fix remaining
violations.
---
 llvm/lib/Transforms/Vectorize/VPlan.h             |  7 ++++++-
 llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp | 11 +++++++----
 llvm/unittests/Transforms/Vectorize/VPlanTest.cpp |  8 +++++---
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/VPlan.h b/llvm/lib/Transforms/Vectorize/VPlan.h
index 1aeed394d7482..983cdc9adbac1 100644
--- a/llvm/lib/Transforms/Vectorize/VPlan.h
+++ b/llvm/lib/Transforms/Vectorize/VPlan.h
@@ -1833,7 +1833,12 @@ class LLVM_ABI_FOR_TEST VPWidenRecipe : public VPRecipeWithIRFlags,
       : VPRecipeWithIRFlags(VPRecipeBase::VPWidenSC, Operands,
                             computeScalarTypeForInstruction(Opcode, Operands),
                             Flags, DL),
-        VPIRMetadata(Metadata), Opcode(Opcode) {}
+        VPIRMetadata(Metadata), Opcode(Opcode) {
+    assert(flagsValidForOpcode(Opcode) &&
+           "Set flags not supported for the provided opcode");
+    assert(hasRequiredFlagsForOpcode(Opcode) &&
+           "Opcode requires specific flags to be set");
+  }
 
   ~VPWidenRecipe() override = default;
 
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 3311a9711cb3f..a254c06f5765d 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -4751,8 +4751,9 @@ optimizeExtendsForPartialReduction(VPSingleDefRecipe *Op) {
     auto *Min = Builder.insert(
         new VPWidenIntrinsicRecipe(IsSigned ? Intrinsic::smin : Intrinsic::umin,
                                    {FreezeX, FreezeY}, SrcTy));
-    auto *AbsDiff =
-        Builder.insert(new VPWidenRecipe(Instruction::Sub, {Max, Min}));
+    auto *AbsDiff = Builder.insert(
+        new VPWidenRecipe(Instruction::Sub, {Max, Min},
+                          VPIRFlags::getDefaultFlags(Instruction::Sub)));
     return Builder.createWidenCast(Instruction::CastOps::ZExt, AbsDiff,
                                    Op->getScalarType());
   }
@@ -4881,12 +4882,14 @@ static void transformToPartialReduction(const VPPartialReductionChain &Chain,
     VPWidenRecipe *NegRecipe;
     if (WidenRecipe->getOpcode() == Instruction::FSub) {
       NegRecipe =
-          new VPWidenRecipe(Instruction::FNeg, {ExtendedOp}, VPIRFlags(),
+          new VPWidenRecipe(Instruction::FNeg, {ExtendedOp},
+                            VPIRFlags::getDefaultFlags(Instruction::FNeg),
                             VPIRMetadata(), DebugLoc::getUnknown());
     } else {
       auto *Zero = Plan.getZero(ElemTy);
       NegRecipe =
-          new VPWidenRecipe(Instruction::Sub, {Zero, ExtendedOp}, VPIRFlags(),
+          new VPWidenRecipe(Instruction::Sub, {Zero, ExtendedOp},
+                            VPIRFlags::getDefaultFlags(Instruction::Sub),
                             VPIRMetadata(), DebugLoc::getUnknown());
     }
     Builder.insert(NegRecipe);
diff --git a/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp b/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
index f10435dfb2da6..084a97db157a5 100644
--- a/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
+++ b/llvm/unittests/Transforms/Vectorize/VPlanTest.cpp
@@ -1128,7 +1128,7 @@ TEST_F(VPRecipeTest, CastVPWidenRecipeToVPUser) {
   SmallVector<VPValue *, 2> Args;
   Args.push_back(Op1);
   Args.push_back(Op2);
-  VPWidenRecipe WidenR(*AI, Args);
+  VPWidenRecipe WidenR(*AI, Args, VPIRFlags::getDefaultFlags(AI->getOpcode()));
 
   checkVPRecipeCastImpl<VPWidenRecipe, VPUser, VPIRMetadata>(&WidenR);
   delete AI;
@@ -1358,7 +1358,8 @@ TEST_F(VPRecipeTest, MayHaveSideEffectsAndMayReadWriteMemory) {
     SmallVector<VPValue *, 2> Args;
     Args.push_back(Op1);
     Args.push_back(Op2);
-    VPWidenRecipe Recipe(*AI, Args);
+    VPWidenRecipe Recipe(*AI, Args,
+                         VPIRFlags::getDefaultFlags(AI->getOpcode()));
     EXPECT_FALSE(Recipe.mayHaveSideEffects());
     EXPECT_FALSE(Recipe.mayReadFromMemory());
     EXPECT_FALSE(Recipe.mayWriteToMemory());
@@ -1546,7 +1547,8 @@ TEST_F(VPRecipeTest, dumpRecipeInPlan) {
   VPValue *ExtVPV2 = Plan.getOrAddLiveIn(ConstantInt::get(Int32, 2));
   Args.push_back(ExtVPV1);
   Args.push_back(ExtVPV2);
-  VPWidenRecipe *WidenR = new VPWidenRecipe(*AI, Args);
+  VPWidenRecipe *WidenR =
+      new VPWidenRecipe(*AI, Args, VPIRFlags::getDefaultFlags(AI->getOpcode()));
   VPBB1->appendRecipe(WidenR);
 
   {