[llvm] [VPlan] Extend tryToFoldLiveIns to fold binary intrinsics (PR #161703)
Ramkumar Ramachandra via llvm-commits
llvm-commits at lists.llvm.org
Thu Oct 2 10:22:40 PDT 2025
https://github.com/artagnon created https://github.com/llvm/llvm-project/pull/161703
InstSimplifyFolder can fold binary intrinsics, so take the opportunity to unify code with getOpcodeOrIntrinsicID, and handle the case. The additional handling of WidenGEP is non-functional, as the GEP is simplified before it is widened, as the included test shows.
>From 77d9eb9ba7ee118241dd9103406c02e3602e35a6 Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <ramkumar.ramachandra at codasip.com>
Date: Thu, 2 Oct 2025 18:05:11 +0100
Subject: [PATCH 1/2] [LV] Pre-commit test for constantfolder-binaryintrinsic
---
.../LoopVectorize/constantfolder.ll | 83 +++++++++++++++++++
1 file changed, 83 insertions(+)
diff --git a/llvm/test/Transforms/LoopVectorize/constantfolder.ll b/llvm/test/Transforms/LoopVectorize/constantfolder.ll
index 66592b0ccf677..0890347f1b6d3 100644
--- a/llvm/test/Transforms/LoopVectorize/constantfolder.ll
+++ b/llvm/test/Transforms/LoopVectorize/constantfolder.ll
@@ -288,3 +288,86 @@ loop.latch:
exit:
ret void
}
+
+define void @const_fold_binaryintrinsic(ptr %dst, i64 %d) {
+; CHECK-LABEL: define void @const_fold_binaryintrinsic(
+; CHECK-SAME: ptr [[DST:%.*]], i64 [[D:%.*]]) {
+; CHECK-NEXT: [[ENTRY:.*:]]
+; CHECK-NEXT: br label %[[VECTOR_PH:.*]]
+; CHECK: [[VECTOR_PH]]:
+; CHECK-NEXT: [[TMP0:%.*]] = call <4 x i64> @llvm.umax.v4i64(<4 x i64> zeroinitializer, <4 x i64> splat (i64 3))
+; CHECK-NEXT: [[TMP1:%.*]] = extractelement <4 x i64> [[TMP0]], i32 3
+; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
+; CHECK: [[VECTOR_BODY]]:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT: store i64 [[TMP1]], ptr [[DST]], align 2
+; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
+; CHECK-NEXT: [[TMP2:%.*]] = icmp eq i64 [[INDEX_NEXT]], 100
+; CHECK-NEXT: br i1 [[TMP2]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP9:![0-9]+]]
+; CHECK: [[MIDDLE_BLOCK]]:
+; CHECK-NEXT: br label %[[EXIT:.*]]
+; CHECK: [[EXIT]]:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop.header
+
+loop.header:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop.latch ]
+ br i1 true, label %loop.latch, label %else
+
+else:
+ br label %loop.latch
+
+loop.latch:
+ %const.0 = phi i64 [ %d, %else ], [ 0, %loop.header ]
+ %trunc = call i64 @llvm.umax.i64(i64 %const.0, i64 3)
+ store i64 %trunc, ptr %dst, align 2
+ %iv.next = add i64 %iv, 1
+ %cmp = icmp ult i64 %iv.next, 100
+ br i1 %cmp, label %loop.header, label %exit
+
+exit:
+ ret void
+}
+
+define void @const_fold_widegep(ptr noalias %A, ptr noalias %B) {
+; CHECK-LABEL: define void @const_fold_widegep(
+; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]]) {
+; CHECK-NEXT: [[ENTRY:.*:]]
+; CHECK-NEXT: br label %[[VECTOR_PH:.*]]
+; CHECK: [[VECTOR_PH]]:
+; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
+; CHECK: [[VECTOR_BODY]]:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT: store ptr [[A]], ptr [[B]], align 8
+; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
+; CHECK-NEXT: [[TMP0:%.*]] = icmp eq i64 [[INDEX_NEXT]], 100
+; CHECK-NEXT: br i1 [[TMP0]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP10:![0-9]+]]
+; CHECK: [[MIDDLE_BLOCK]]:
+; CHECK-NEXT: br label %[[EXIT:.*]]
+; CHECK: [[EXIT]]:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop.header
+
+loop.header:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop.latch ]
+ br i1 true, label %loop.latch, label %else
+
+else:
+ br label %loop.latch
+
+loop.latch:
+ %const.0 = phi i64 [ 0, %loop.header ], [ %iv, %else ]
+ %gep.A = getelementptr i64, ptr %A, i64 %const.0
+ %gep.B = getelementptr i64, ptr %B, i64 %const.0
+ store ptr %gep.A, ptr %gep.B
+ %iv.next = add nuw nsw i64 %iv, 1
+ %exit.cond = icmp ult i64 %iv.next, 100
+ br i1 %exit.cond, label %loop.header, label %exit
+
+exit:
+ ret void
+}
>From a57f4e41a443905648148bf46b0c528b2fed4e24 Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <ramkumar.ramachandra at codasip.com>
Date: Thu, 2 Oct 2025 18:07:40 +0100
Subject: [PATCH 2/2] [VPlan] Extend tryToFoldLiveIns to fold binary intrinsics
InstSimplifyFolder can fold binary intrinsics, so take the opportunity
to unify code with getOpcodeOrIntrinsicID, and handle the case. The
additional handling of WidenGEP is non-functional, as the GEP is
simplified before it is widened, as the included test shows.
---
.../Transforms/Vectorize/VPlanTransforms.cpp | 66 ++++++++++---------
.../LoopVectorize/constantfolder.ll | 4 +-
2 files changed, 37 insertions(+), 33 deletions(-)
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index acdb37996a443..44938a9ed67f9 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -942,10 +942,29 @@ static void recursivelyDeleteDeadRecipes(VPValue *V) {
}
}
+namespace {
+/// 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());
+ })
+ .Default([](auto *) { return std::nullopt; });
+}
+} // namespace
+
/// 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,
+static Value *tryToFoldLiveIns(VPSingleDefRecipe &R,
+ std::pair<bool, unsigned> OpcodeOrIID,
ArrayRef<VPValue *> Operands,
const DataLayout &DL, VPTypeAnalysis &TypeInfo) {
SmallVector<Value *, 4> Ops;
@@ -956,6 +975,15 @@ static Value *tryToFoldLiveIns(const VPRecipeBase &R, unsigned Opcode,
}
InstSimplifyFolder Folder(DL);
+ if (OpcodeOrIID.first) {
+ if (R.getNumOperands() != 2)
+ return nullptr;
+ unsigned ID = OpcodeOrIID.second;
+ return Folder.FoldBinaryIntrinsic(
+ ID, Ops[0], Ops[1], TypeInfo.inferScalarType(R.getVPSingleValue()),
+ R.getUnderlyingInstr());
+ }
+ unsigned Opcode = OpcodeOrIID.second;
if (Instruction::isBinaryOp(Opcode))
return Folder.FoldBinOp(static_cast<Instruction::BinaryOps>(Opcode), Ops[0],
Ops[1]);
@@ -1005,19 +1033,13 @@ static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
// Simplification of live-in IR values for SingleDef recipes using
// InstSimplifyFolder.
- if (TypeSwitch<VPRecipeBase *, bool>(&R)
- .Case<VPInstruction, VPWidenRecipe, VPWidenCastRecipe,
- VPReplicateRecipe, VPWidenSelectRecipe>([&](auto *I) {
- const DataLayout &DL =
- Plan->getScalarHeader()->getIRBasicBlock()->getDataLayout();
- Value *V = tryToFoldLiveIns(*I, I->getOpcode(), I->operands(), DL,
- TypeInfo);
- if (V)
- I->replaceAllUsesWith(Plan->getOrAddLiveIn(V));
- return V;
- })
- .Default([](auto *) { return false; }))
- return;
+ if (auto OpcodeOrIID = getOpcodeOrIntrinsicID(Def)) {
+ const DataLayout &DL =
+ Plan->getScalarHeader()->getIRBasicBlock()->getDataLayout();
+ if (Value *V =
+ tryToFoldLiveIns(*Def, *OpcodeOrIID, Def->operands(), DL, TypeInfo))
+ return Def->replaceAllUsesWith(Plan->getOrAddLiveIn(V));
+ }
// Fold PredPHI LiveIn -> LiveIn.
if (auto *PredPHI = dyn_cast<VPPredInstPHIRecipe>(&R)) {
@@ -1970,22 +1992,6 @@ struct VPCSEDenseMapInfo : public DenseMapInfo<VPSingleDefRecipe *> {
return Def == getEmptyKey() || Def == getTombstoneKey();
}
- /// 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());
- })
- .Default([](auto *) { return std::nullopt; });
- }
-
/// If recipe \p R will lower to a GEP with a non-i8 source element type,
/// return that source element type.
static Type *getGEPSourceElementType(const VPSingleDefRecipe *R) {
diff --git a/llvm/test/Transforms/LoopVectorize/constantfolder.ll b/llvm/test/Transforms/LoopVectorize/constantfolder.ll
index 0890347f1b6d3..bbd208e8a0586 100644
--- a/llvm/test/Transforms/LoopVectorize/constantfolder.ll
+++ b/llvm/test/Transforms/LoopVectorize/constantfolder.ll
@@ -295,12 +295,10 @@ define void @const_fold_binaryintrinsic(ptr %dst, i64 %d) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: br label %[[VECTOR_PH:.*]]
; CHECK: [[VECTOR_PH]]:
-; CHECK-NEXT: [[TMP0:%.*]] = call <4 x i64> @llvm.umax.v4i64(<4 x i64> zeroinitializer, <4 x i64> splat (i64 3))
-; CHECK-NEXT: [[TMP1:%.*]] = extractelement <4 x i64> [[TMP0]], i32 3
; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
-; CHECK-NEXT: store i64 [[TMP1]], ptr [[DST]], align 2
+; CHECK-NEXT: store i64 3, ptr [[DST]], align 2
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
; CHECK-NEXT: [[TMP2:%.*]] = icmp eq i64 [[INDEX_NEXT]], 100
; CHECK-NEXT: br i1 [[TMP2]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP9:![0-9]+]]
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