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[VPlan] Extend tryToFoldLiveIns to fold binary intrinsics #161703

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[VPlan] Extend tryToFoldLiveIns to fold binary intrinsics #161703

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77d9eb9
[LV] Pre-commit test for constantfolder-binaryintrinsic
artagnon Oct 2, 2025
a57f4e4
[VPlan] Extend tryToFoldLiveIns to fold binary intrinsics
artagnon Oct 2, 2025
b4e0291
[ISFolder, VPlan] FMFSource = null default
artagnon Oct 2, 2025
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2 changes: 1 addition & 1 deletion llvm/include/llvm/Analysis/InstSimplifyFolder.h
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Original file line number Diff line number Diff line change
Expand Up @@ -120,7 +120,7 @@ class LLVM_ABI InstSimplifyFolder final : public IRBuilderFolder {
}

Value *FoldBinaryIntrinsic(Intrinsic::ID ID, Value *LHS, Value *RHS, Type *Ty,
Instruction *FMFSource) const override {
Instruction *FMFSource = nullptr) const override {
return simplifyBinaryIntrinsic(ID, Ty, LHS, RHS, SQ,
dyn_cast_if_present<CallBase>(FMFSource));
}
Expand Down
65 changes: 35 additions & 30 deletions llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -956,6 +975,14 @@ static Value *tryToFoldLiveIns(const VPRecipeBase &R, unsigned Opcode,
}

InstSimplifyFolder Folder(DL);
if (OpcodeOrIID.first) {
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Should we just call getOpcodeOrIntrinsicID on R here instead of plumbing it through as an argument?

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@artagnon artagnon Oct 16, 2025 •
edited
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Good idea. Will update patch after @fhahn's bugfix to CSE lands.

if (R.getNumOperands() != 2)
return nullptr;
unsigned ID = OpcodeOrIID.second;
return Folder.FoldBinaryIntrinsic(
ID, Ops[0], Ops[1], TypeInfo.inferScalarType(R.getVPSingleValue()));
}
unsigned Opcode = OpcodeOrIID.second;
if (Instruction::isBinaryOp(Opcode))
return Folder.FoldBinOp(static_cast<Instruction::BinaryOps>(Opcode), Ops[0],
Ops[1]);
Expand Down Expand Up @@ -1005,19 +1032,13 @@ 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)) {
Expand Down Expand Up @@ -1970,22 +1991,6 @@ 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) {
Expand Down
81 changes: 81 additions & 0 deletions llvm/test/Transforms/LoopVectorize/constantfolder.ll
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Expand Up @@ -288,3 +288,84 @@ 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: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
; 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]+]]
; 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
}