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[TableGen] HasOneUse builtin predicate on PatFrags #91578

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Merged
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May 20, 2024
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[TableGen] HasOneUse builtin predicate on PatFrags #91578

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4 changes: 4 additions & 0 deletions llvm/include/llvm/CodeGen/GlobalISel/GIMatchTableExecutor.h
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Original file line number Diff line number Diff line change
Expand Up @@ -212,6 +212,10 @@ enum {
/// - InsnID(ULEB128) - Instruction ID
GIM_CheckHasNoUse,

/// Check if there's one use of the first result.
/// - InsnID(ULEB128) - Instruction ID
GIM_CheckHasOneUse,

/// Check the type for the specified operand
/// - InsnID(ULEB128) - Instruction ID
/// - OpIdx(ULEB128) - Operand index
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17 changes: 17 additions & 0 deletions llvm/include/llvm/CodeGen/GlobalISel/GIMatchTableExecutorImpl.h
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Expand Up @@ -468,7 +468,24 @@ bool GIMatchTableExecutor::executeMatchTable(
if (handleReject() == RejectAndGiveUp)
return false;
}
break;
}
case GIM_CheckHasOneUse: {
uint64_t InsnID = readULEB();

DEBUG_WITH_TYPE(TgtExecutor::getName(),
dbgs() << CurrentIdx << ": GIM_CheckHasOneUse(MIs["
<< InsnID << "]\n");

const MachineInstr *MI = State.MIs[InsnID];
assert(MI && "Used insn before defined");
assert(MI->getNumDefs() > 0 && "No defs");
const Register Res = MI->getOperand(0).getReg();
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We might want an extended variant that can handle multiple defs at some point

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Yes, it depends on how many of these are emitted at once for a given pattern, we need to see more use first
Though this is just 2 bytes on average (1 byte opcode + 1 byte id) so it's not a big deal unless this is emitted in bulk in a ton of rules


if (!MRI.hasOneNonDBGUse(Res)) {
if (handleReject() == RejectAndGiveUp)
return false;
}
break;
}
case GIM_CheckAtomicOrdering: {
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3 changes: 3 additions & 0 deletions llvm/include/llvm/Target/TargetSelectionDAG.td
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Expand Up @@ -884,6 +884,9 @@ class PatFrags<dag ops, list<dag> frags, code pred = [{}],
// If set to true, a predicate is added that checks for the absence of use of
// the first result.
bit HasNoUse = ?;
// If set to true, a predicate is added that checks for the sole use of
// the first result.
bit HasOneUse = ?;

// Is the desired pre-packaged predicate for a load?
bit IsLoad = ?;
Expand Down
30 changes: 22 additions & 8 deletions llvm/test/TableGen/predicate-patfags.td
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@@ -1,5 +1,7 @@
// RUN: llvm-tblgen -gen-dag-isel -I %p/../../include -I %p/Common %s 2>&1 | FileCheck -check-prefix=SDAG %s
// RUN: llvm-tblgen -gen-global-isel -I %p/../../include -I %p/Common %s 2>&1 | FileCheck -check-prefix=GISEL %s
// RUN: llvm-tblgen -gen-dag-isel -I %p/../../include -I %p/Common %s 2>&1 | FileCheck -check-prefixes=SDAG,SCUSTOM %s
// RUN: llvm-tblgen -gen-dag-isel -I %p/../../include -I %p/Common %s -DHASONEUSE 2>&1 | FileCheck -check-prefixes=SDAG,SBUILTIN %s
// RUN: llvm-tblgen -gen-global-isel -I %p/../../include -I %p/Common %s 2>&1 | FileCheck -check-prefixes=GISEL,GCUSTOM %s
// RUN: llvm-tblgen -gen-global-isel -I %p/../../include -I %p/Common %s -DHASONEUSE 2>&1 | FileCheck -check-prefixes=GISEL,GBUILTIN %s

include "llvm/Target/Target.td"
include "GlobalISelEmitterCommon.td"
Expand Down Expand Up @@ -31,11 +33,16 @@ def : GINodeEquiv<G_TGT_MUL24, TGTmul24_impl>;

def TGTmul24_oneuse : PatFrag<
(ops node:$src0, node:$src1),
(TGTmul24 $src0, $src1),
[{ return N->hasOneUse(); }]> {
(TGTmul24 $src0, $src1)
#ifndef HASONEUSE
, [{ return N->hasOneUse(); }]> {
let GISelPredicateCode = [{
return MRI->hasOneNonDBGUse(MI.getOperand(0).getReg());
}];
#else
> {
let HasOneUse = 1;
#endif
}

// SDAG: OPC_CheckOpcode, TARGET_VAL(ISD::INTRINSIC_W_CHAIN),
Expand All @@ -44,19 +51,26 @@ def TGTmul24_oneuse : PatFrag<
// SDAG: OPC_CheckOpcode, TARGET_VAL(TargetISD::MUL24),
// SDAG: OPC_CheckPredicate0, // Predicate_TGTmul24_oneuse

// SCUSTOM: return N->hasOneUse();
// SBUILTIN: if (!SDValue(N, 0).hasOneUse()) return false;

// GISEL: GIM_CheckOpcode, /*MI*/1, GIMT_Encode2(TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS),
// GISEL: GIM_CheckIntrinsicID, /*MI*/1, /*Op*/1, GIMT_Encode2(Intrinsic::tgt_mul24),
// GISEL: GIM_CheckCxxInsnPredicate, /*MI*/1, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_TGTmul24_oneuse),
// GBUILTIN: GIM_CheckHasOneUse, /*MI*/1,
// GCUSTOM: GIM_CheckCxxInsnPredicate, /*MI*/1, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_TGTmul24_oneuse),

// GISEL: GIM_CheckOpcode, /*MI*/1, GIMT_Encode2(TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS),
// GISEL: GIM_CheckIntrinsicID, /*MI*/1, /*Op*/1, GIMT_Encode2(Intrinsic::tgt_mul24),
// GISEL: GIM_CheckCxxInsnPredicate, /*MI*/1, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_TGTmul24_oneuse),
// GBUILTIN: GIM_CheckHasOneUse, /*MI*/1,
// GCUSTOM: GIM_CheckCxxInsnPredicate, /*MI*/1, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_TGTmul24_oneuse),

// GISEL: GIM_CheckOpcode, /*MI*/1, GIMT_Encode2(MyTarget::G_TGT_MUL24),
// GISEL: GIM_CheckCxxInsnPredicate, /*MI*/1, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_TGTmul24_oneuse),
// GBUILTIN: GIM_CheckHasOneUse, /*MI*/1,
// GCUSTOM: GIM_CheckCxxInsnPredicate, /*MI*/1, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_TGTmul24_oneuse),

// GISEL: GIM_CheckOpcode, /*MI*/1, GIMT_Encode2(MyTarget::G_TGT_MUL24),
// GISEL: GIM_CheckCxxInsnPredicate, /*MI*/1, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_TGTmul24_oneuse),
// GBUILTIN: GIM_CheckHasOneUse, /*MI*/1,
// GCUSTOM: GIM_CheckCxxInsnPredicate, /*MI*/1, /*FnId*/GIMT_Encode2(GICXXPred_MI_Predicate_TGTmul24_oneuse),
def inst_mad24 : I<
(outs GPR32:$dst),
(ins GPR32:$src0, GPR32:$src1, GPR32:$src2),
Expand Down
7 changes: 6 additions & 1 deletion llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp
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Expand Up @@ -903,7 +903,7 @@ TreePredicateFn::TreePredicateFn(TreePattern *N) : PatFragRec(N) {
}

bool TreePredicateFn::hasPredCode() const {
return isLoad() || isStore() || isAtomic() || hasNoUse() ||
return isLoad() || isStore() || isAtomic() || hasNoUse() || hasOneUse() ||
!PatFragRec->getRecord()->getValueAsString("PredicateCode").empty();
}

Expand Down Expand Up @@ -1140,6 +1140,8 @@ std::string TreePredicateFn::getPredCode() const {

if (hasNoUse())
Code += "if (!SDValue(N, 0).use_empty()) return false;\n";
if (hasOneUse())
Code += "if (!SDValue(N, 0).hasOneUse()) return false;\n";

std::string PredicateCode =
std::string(PatFragRec->getRecord()->getValueAsString("PredicateCode"));
Expand Down Expand Up @@ -1187,6 +1189,9 @@ bool TreePredicateFn::usesOperands() const {
bool TreePredicateFn::hasNoUse() const {
return isPredefinedPredicateEqualTo("HasNoUse", true);
}
bool TreePredicateFn::hasOneUse() const {
return isPredefinedPredicateEqualTo("HasOneUse", true);
}
bool TreePredicateFn::isLoad() const {
return isPredefinedPredicateEqualTo("IsLoad", true);
}
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2 changes: 2 additions & 0 deletions llvm/utils/TableGen/Common/CodeGenDAGPatterns.h
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Expand Up @@ -533,6 +533,8 @@ class TreePredicateFn {

// Check if the HasNoUse predicate is set.
bool hasNoUse() const;
// Check if the HasOneUse predicate is set.
bool hasOneUse() const;

// Is the desired predefined predicate for a load?
bool isLoad() const;
Expand Down
23 changes: 23 additions & 0 deletions llvm/utils/TableGen/Common/GlobalISel/GlobalISelMatchTable.h
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Expand Up @@ -806,6 +806,7 @@ class PredicateMatcher {
IPM_MemoryAlignment,
IPM_VectorSplatImm,
IPM_NoUse,
IPM_OneUse,
IPM_GenericPredicate,
IPM_MIFlags,
OPM_SameOperand,
Expand Down Expand Up @@ -1691,6 +1692,28 @@ class NoUsePredicateMatcher : public InstructionPredicateMatcher {
}
};

/// Generates code to check that the first result has only one use.
class OneUsePredicateMatcher : public InstructionPredicateMatcher {
public:
OneUsePredicateMatcher(unsigned InsnVarID)
: InstructionPredicateMatcher(IPM_OneUse, InsnVarID) {}

static bool classof(const PredicateMatcher *P) {
return P->getKind() == IPM_OneUse;
}

bool isIdentical(const PredicateMatcher &B) const override {
return InstructionPredicateMatcher::isIdentical(B);
}

void emitPredicateOpcodes(MatchTable &Table,
RuleMatcher &Rule) const override {
Table << MatchTable::Opcode("GIM_CheckHasOneUse")
<< MatchTable::Comment("MI") << MatchTable::ULEB128Value(InsnVarID)
<< MatchTable::LineBreak;
}
};

/// Generates code to check that a set of predicates and operands match for a
/// particular instruction.
///
Expand Down
6 changes: 5 additions & 1 deletion llvm/utils/TableGen/GlobalISelEmitter.cpp
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Expand Up @@ -207,7 +207,7 @@ static Error isTrivialOperatorNode(const TreePatternNode &N) {
if (Predicate.isImmediatePattern())
continue;

if (Predicate.hasNoUse())
if (Predicate.hasNoUse() || Predicate.hasOneUse())
continue;

if (Predicate.isNonExtLoad() || Predicate.isAnyExtLoad() ||
Expand Down Expand Up @@ -782,6 +782,10 @@ Expected<InstructionMatcher &> GlobalISelEmitter::createAndImportSelDAGMatcher(
InsnMatcher.addPredicate<NoUsePredicateMatcher>();
HasAddedBuiltinMatcher = true;
}
if (Predicate.hasOneUse()) {
InsnMatcher.addPredicate<OneUsePredicateMatcher>();
HasAddedBuiltinMatcher = true;
}

if (Predicate.hasGISelPredicateCode()) {
if (Predicate.usesOperands()) {
Expand Down
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