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[slp][profcheck] Mark selects as having unknown profile #162960

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Oct 13, 2025
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[slp][profcheck] Mark selects as having unknown profile #162960

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5 changes: 5 additions & 0 deletions llvm/include/llvm/IR/IRBuilder.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2548,6 +2548,11 @@ class IRBuilderBase {
std::optional<RoundingMode> Rounding = std::nullopt,
std::optional<fp::ExceptionBehavior> Except = std::nullopt);

LLVM_ABI Value *CreateSelectWithUnknownProfile(Value *C, Value *True,
Value *False,
StringRef PassName,
const Twine &Name = "");

LLVM_ABI Value *CreateSelect(Value *C, Value *True, Value *False,
const Twine &Name = "",
Instruction *MDFrom = nullptr);
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13 changes: 13 additions & 0 deletions llvm/lib/IR/IRBuilder.cpp
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Expand Up @@ -25,6 +25,7 @@
#include "llvm/IR/Module.h"
#include "llvm/IR/NoFolder.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/ProfDataUtils.h"
#include "llvm/IR/Statepoint.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
Expand Down Expand Up @@ -1002,6 +1003,18 @@ CallInst *IRBuilderBase::CreateConstrainedFPCall(
return C;
}

Value *IRBuilderBase::CreateSelectWithUnknownProfile(Value *C, Value *True,
Value *False,
StringRef PassName,
const Twine &Name) {
Value *Ret = CreateSelectFMF(C, True, False, {}, Name);
if (auto *SI = dyn_cast<SelectInst>(Ret)) {
setExplicitlyUnknownBranchWeightsIfProfiled(
*SI, *SI->getParent()->getParent(), PassName);
}
return Ret;
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Could use this in 01e19e8 as well -- the tradeoff being having to pass the pass name, but getting to keep IRBuilder usage. The pass name requirement is annoying.

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Ack.

FWIW, I'm actively thinking how to avoid the explicit name and still get the property we want - namely, identification of origin of "unknowns", which we can use to farm out opportunities for better profiling. If there aren't too many cases, maybe it's not too bad, but I want to have an alternative ready.

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follow - up in PR #163116.

}

Value *IRBuilderBase::CreateSelect(Value *C, Value *True, Value *False,
const Twine &Name, Instruction *MDFrom) {
return CreateSelectFMF(C, True, False, {}, Name, MDFrom);
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15 changes: 9 additions & 6 deletions llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
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Expand Up @@ -19456,7 +19456,8 @@ Value *BoUpSLP::vectorizeTree(TreeEntry *E) {
}
assert(getNumElements(Cond->getType()) == TrueNumElements &&
"Cannot vectorize Instruction::Select");
Value *V = Builder.CreateSelect(Cond, True, False);
Value *V =
Builder.CreateSelectWithUnknownProfile(Cond, True, False, DEBUG_TYPE);
V = FinalShuffle(V, E);

E->VectorizedValue = V;
Expand Down Expand Up @@ -23576,18 +23577,19 @@ class HorizontalReduction {
switch (Kind) {
case RecurKind::Or: {
if (UseSelect && OpTy == CmpInst::makeCmpResultType(OpTy))
return Builder.CreateSelect(
return Builder.CreateSelectWithUnknownProfile(
LHS, ConstantInt::getAllOnesValue(CmpInst::makeCmpResultType(OpTy)),
RHS, Name);
RHS, DEBUG_TYPE, Name);
unsigned RdxOpcode = RecurrenceDescriptor::getOpcode(Kind);
return Builder.CreateBinOp((Instruction::BinaryOps)RdxOpcode, LHS, RHS,
Name);
}
case RecurKind::And: {
if (UseSelect && OpTy == CmpInst::makeCmpResultType(OpTy))
return Builder.CreateSelect(
return Builder.CreateSelectWithUnknownProfile(
LHS, RHS,
ConstantInt::getNullValue(CmpInst::makeCmpResultType(OpTy)), Name);
ConstantInt::getNullValue(CmpInst::makeCmpResultType(OpTy)),
DEBUG_TYPE, Name);
unsigned RdxOpcode = RecurrenceDescriptor::getOpcode(Kind);
return Builder.CreateBinOp((Instruction::BinaryOps)RdxOpcode, LHS, RHS,
Name);
Expand All @@ -23608,7 +23610,8 @@ class HorizontalReduction {
if (UseSelect) {
CmpInst::Predicate Pred = llvm::getMinMaxReductionPredicate(Kind);
Value *Cmp = Builder.CreateICmp(Pred, LHS, RHS, Name);
return Builder.CreateSelect(Cmp, LHS, RHS, Name);
return Builder.CreateSelectWithUnknownProfile(Cmp, LHS, RHS, DEBUG_TYPE,
Name);
}
[[fallthrough]];
case RecurKind::FMax:
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76 changes: 0 additions & 76 deletions llvm/utils/profcheck-xfail.txt
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Expand Up @@ -1311,82 +1311,6 @@ Transforms/SimpleLoopUnswitch/pr60736.ll
Transforms/SimpleLoopUnswitch/trivial-unswitch-freeze-individual-conditions.ll
Transforms/SimpleLoopUnswitch/trivial-unswitch.ll
Transforms/SimpleLoopUnswitch/trivial-unswitch-logical-and-or.ll
Transforms/SLPVectorizer/AArch64/gather-root.ll
Transforms/SLPVectorizer/AArch64/horizontal.ll
Transforms/SLPVectorizer/AArch64/loadi8.ll
Transforms/SLPVectorizer/AArch64/phi-node-bitwidt-op-not.ll
Transforms/SLPVectorizer/AArch64/uselistorder.ll
Transforms/SLPVectorizer/AArch64/vec3-reorder-reshuffle.ll
Transforms/SLPVectorizer/AArch64/vectorizable-selects-min-max.ll
Transforms/SLPVectorizer/AArch64/vectorizable-selects-uniform-cmps.ll
Transforms/SLPVectorizer/AMDGPU/horizontal-store.ll
Transforms/SLPVectorizer/bool-logical-op-reduction-with-poison.ll
Transforms/SLPVectorizer/call-arg-reduced-by-minbitwidth.ll
Transforms/SLPVectorizer/const-bool-logical-or-reduction.ll
Transforms/SLPVectorizer/extracts-with-undefs.ll
Transforms/SLPVectorizer/freeze-signedness-missed.ll
Transforms/SLPVectorizer/gathered-consecutive-loads-different-types.ll
Transforms/SLPVectorizer/gather_extract_from_vectorbuild.ll
Transforms/SLPVectorizer/insert-element-build-vector-const.ll
Transforms/SLPVectorizer/insert-element-build-vector-inseltpoison.ll
Transforms/SLPVectorizer/insert-element-build-vector.ll
Transforms/SLPVectorizer/logical-ops-poisonous-repeated.ll
Transforms/SLPVectorizer/minbitwidth-node-with-multi-users.ll
Transforms/SLPVectorizer/minbitwidth-user-not-min.ll
Transforms/SLPVectorizer/partial-register-extract.ll
Transforms/SLPVectorizer/reduction-gather-non-scheduled-extracts.ll
Transforms/SLPVectorizer/reorder-node.ll
Transforms/SLPVectorizer/reused-buildvector-matching-vectorized-node.ll
Transforms/SLPVectorizer/revec.ll
Transforms/SLPVectorizer/RISCV/remarks_cmp_sel_min_max.ll
Transforms/SLPVectorizer/RISCV/remarks-insert-into-small-vector.ll
Transforms/SLPVectorizer/RISCV/reordered-interleaved-loads.ll
Transforms/SLPVectorizer/RISCV/revec.ll
Transforms/SLPVectorizer/RISCV/select-profitability.ll
Transforms/SLPVectorizer/RISCV/shuffled-gather-casted.ll
Transforms/SLPVectorizer/RISCV/unsigned-node-trunc-with-signed-users.ll
Transforms/SLPVectorizer/slp-deleted-inst.ll
Transforms/SLPVectorizer/SystemZ/cmp-ptr-minmax.ll
Transforms/SLPVectorizer/SystemZ/ext-not-resized-op-resized.ll
Transforms/SLPVectorizer/SystemZ/minbitwidth-trunc.ll
Transforms/SLPVectorizer/X86/bool-mask.ll
Transforms/SLPVectorizer/X86/bv-root-part-of-graph.ll
Transforms/SLPVectorizer/X86/cmp-after-intrinsic-call-minbitwidth.ll
Transforms/SLPVectorizer/X86/cmp-as-alternate-ops.ll
Transforms/SLPVectorizer/X86/cmp_sel.ll
Transforms/SLPVectorizer/X86/crash_7zip.ll
Transforms/SLPVectorizer/X86/crash_clear_undefs.ll
Transforms/SLPVectorizer/X86/crash_cmpop.ll
Transforms/SLPVectorizer/X86/debug-counter.ll
Transforms/SLPVectorizer/X86/debug-info-salvage.ll
Transforms/SLPVectorizer/X86/extractelement-single-use-many-nodes.ll
Transforms/SLPVectorizer/X86/extracts-non-extendable.ll
Transforms/SLPVectorizer/X86/ext-used-scalar-different-bitwidth.ll
Transforms/SLPVectorizer/X86/gather-node-same-as-vect-but-order.ll
Transforms/SLPVectorizer/X86/horizontal-minmax.ll
Transforms/SLPVectorizer/X86/insert-after-bundle.ll
Transforms/SLPVectorizer/X86/jumbled-load-multiuse.ll
Transforms/SLPVectorizer/X86/minbitwidth-icmp-to-trunc.ll
Transforms/SLPVectorizer/X86/minbw-user-non-sizable.ll
Transforms/SLPVectorizer/X86/non-load-reduced-as-part-of-bv.ll
Transforms/SLPVectorizer/X86/ordering-bug.ll
Transforms/SLPVectorizer/X86/phi-node-bitwidt-op-not.ll
Transforms/SLPVectorizer/X86/phi-node-reshuffled-part.ll
Transforms/SLPVectorizer/X86/pr46983.ll
Transforms/SLPVectorizer/X86/pr49933.ll
Transforms/SLPVectorizer/X86/propagate_ir_flags.ll
Transforms/SLPVectorizer/X86/reduction-bool-logic-op-inside.ll
Transforms/SLPVectorizer/X86/reduction-logical.ll
Transforms/SLPVectorizer/X86/resized-bv-values-non-power-of2-node.ll
Transforms/SLPVectorizer/X86/reused-reductions-with-minbitwidth.ll
Transforms/SLPVectorizer/X86/select-reduction-op.ll
Transforms/SLPVectorizer/X86/shrink_after_reorder.ll
Transforms/SLPVectorizer/X86/subvector-minbitwidth-unsigned-value.ll
Transforms/SLPVectorizer/X86/undef_vect.ll
Transforms/SLPVectorizer/X86/used-reduced-op.ll
Transforms/SLPVectorizer/X86/vec3-reorder-reshuffle.ll
Transforms/SLPVectorizer/X86/vectorize-widest-phis.ll
Transforms/SLPVectorizer/X86/whole-registers-compare.ll
Transforms/SROA/addrspacecast.ll
Transforms/SROA/phi-and-select.ll
Transforms/SROA/phi-gep.ll
Expand Down