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jyli0116 merged 3 commits into from
Aug 4, 2025
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[GlobalISel] Add constant matcher for APInt #151357

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[GlobalISel] Add constant matcher for APInt
jyli0116 Jul 30, 2025
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67 changes: 48 additions & 19 deletions llvm/include/llvm/CodeGen/GlobalISel/MIPatternMatch.h
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Original file line number Diff line number Diff line change
Expand Up @@ -192,63 +192,92 @@ m_GFCstOrSplat(std::optional<FPValueAndVReg> &FPValReg) {

/// Matcher for a specific constant value.
struct SpecificConstantMatch {
int64_t RequestedVal;
SpecificConstantMatch(int64_t RequestedVal) : RequestedVal(RequestedVal) {}
APInt RequestedVal;
SpecificConstantMatch(APInt RequestedVal) : RequestedVal(RequestedVal) {}
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@arsenm arsenm Aug 1, 2025

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const ref

bool match(const MachineRegisterInfo &MRI, Register Reg) {
int64_t MatchedVal;
return mi_match(Reg, MRI, m_ICst(MatchedVal)) && MatchedVal == RequestedVal;
APInt MatchedVal;
if (mi_match(Reg, MRI, m_ICst(MatchedVal))) {
if (MatchedVal.getBitWidth() > RequestedVal.getBitWidth())
RequestedVal = RequestedVal.sext(MatchedVal.getBitWidth());
else
MatchedVal = MatchedVal.sext(RequestedVal.getBitWidth());

return APInt::isSameValue(MatchedVal, RequestedVal);
}
return false;
}
};

/// Matches a constant equal to \p RequestedValue.
inline SpecificConstantMatch m_SpecificICst(APInt RequestedValue) {
return SpecificConstantMatch(std::move(RequestedValue));
}

inline SpecificConstantMatch m_SpecificICst(int64_t RequestedValue) {
return SpecificConstantMatch(RequestedValue);
return SpecificConstantMatch(APInt(64, RequestedValue, /* isSigned */ true));
}

/// Matcher for a specific constant splat.
struct SpecificConstantSplatMatch {
int64_t RequestedVal;
SpecificConstantSplatMatch(int64_t RequestedVal)
: RequestedVal(RequestedVal) {}
APInt RequestedVal;
SpecificConstantSplatMatch(APInt RequestedVal) : RequestedVal(RequestedVal) {}
bool match(const MachineRegisterInfo &MRI, Register Reg) {
return isBuildVectorConstantSplat(Reg, MRI, RequestedVal,
/* AllowUndef */ false);
}
};

/// Matches a constant splat of \p RequestedValue.
inline SpecificConstantSplatMatch m_SpecificICstSplat(APInt RequestedValue) {
return SpecificConstantSplatMatch(std::move(RequestedValue));
}

inline SpecificConstantSplatMatch m_SpecificICstSplat(int64_t RequestedValue) {
return SpecificConstantSplatMatch(RequestedValue);
return SpecificConstantSplatMatch(
APInt(64, RequestedValue, /* isSigned */ true));
}

/// Matcher for a specific constant or constant splat.
struct SpecificConstantOrSplatMatch {
int64_t RequestedVal;
SpecificConstantOrSplatMatch(int64_t RequestedVal)
APInt RequestedVal;
SpecificConstantOrSplatMatch(APInt RequestedVal)
: RequestedVal(RequestedVal) {}
bool match(const MachineRegisterInfo &MRI, Register Reg) {
int64_t MatchedVal;
if (mi_match(Reg, MRI, m_ICst(MatchedVal)) && MatchedVal == RequestedVal)
return true;
APInt MatchedVal;
if (mi_match(Reg, MRI, m_ICst(MatchedVal))) {
if (MatchedVal.getBitWidth() > RequestedVal.getBitWidth())
RequestedVal = RequestedVal.sext(MatchedVal.getBitWidth());
else
MatchedVal = MatchedVal.sext(RequestedVal.getBitWidth());

if (APInt::isSameValue(MatchedVal, RequestedVal))
return true;
}
return isBuildVectorConstantSplat(Reg, MRI, RequestedVal,
/* AllowUndef */ false);
}
};

/// Matches a \p RequestedValue constant or a constant splat of \p
/// RequestedValue.
inline SpecificConstantOrSplatMatch
m_SpecificICstOrSplat(APInt RequestedValue) {
return SpecificConstantOrSplatMatch(std::move(RequestedValue));
}

inline SpecificConstantOrSplatMatch
m_SpecificICstOrSplat(int64_t RequestedValue) {
return SpecificConstantOrSplatMatch(RequestedValue);
return SpecificConstantOrSplatMatch(
APInt(64, RequestedValue, /* isSigned */ true));
}

///{
/// Convenience matchers for specific integer values.
inline SpecificConstantMatch m_ZeroInt() { return SpecificConstantMatch(0); }
inline SpecificConstantMatch m_ZeroInt() {
return SpecificConstantMatch(APInt(64, 0));
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@arsenm arsenm Aug 1, 2025

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Better to use the isNullValue in APInt (really for all of these, should follow along with the IR pattern matcher structure)

}
inline SpecificConstantMatch m_AllOnesInt() {
return SpecificConstantMatch(-1);
return SpecificConstantMatch(APInt(64, -1, /* isSigned */ true));
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@davemgreen davemgreen Aug 1, 2025

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Maybe use getAllOnes(64) too, although I am unsure about treating it like a isSigned. It might not be necessary here because we would not see a larger value?

}
///}

/// Matcher for a specific register.
struct SpecificRegisterMatch {
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12 changes: 12 additions & 0 deletions llvm/include/llvm/CodeGen/GlobalISel/Utils.h
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Expand Up @@ -459,12 +459,24 @@ LLVM_ABI bool isBuildVectorConstantSplat(const Register Reg,
const MachineRegisterInfo &MRI,
int64_t SplatValue, bool AllowUndef);

/// Return true if the specified register is defined by G_BUILD_VECTOR or
/// G_BUILD_VECTOR_TRUNC where all of the elements are \p SplatValue or undef.
LLVM_ABI bool isBuildVectorConstantSplat(const Register Reg,
const MachineRegisterInfo &MRI,
APInt SplatValue, bool AllowUndef);

/// Return true if the specified instruction is a G_BUILD_VECTOR or
/// G_BUILD_VECTOR_TRUNC where all of the elements are \p SplatValue or undef.
LLVM_ABI bool isBuildVectorConstantSplat(const MachineInstr &MI,
const MachineRegisterInfo &MRI,
int64_t SplatValue, bool AllowUndef);

/// Return true if the specified instruction is a G_BUILD_VECTOR or
/// G_BUILD_VECTOR_TRUNC where all of the elements are \p SplatValue or undef.
LLVM_ABI bool isBuildVectorConstantSplat(const MachineInstr &MI,
const MachineRegisterInfo &MRI,
APInt SplatValue, bool AllowUndef);

/// Return true if the specified instruction is a G_BUILD_VECTOR or
/// G_BUILD_VECTOR_TRUNC where all of the elements are 0 or undef.
LLVM_ABI bool isBuildVectorAllZeros(const MachineInstr &MI,
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22 changes: 22 additions & 0 deletions llvm/lib/CodeGen/GlobalISel/Utils.cpp
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Expand Up @@ -1401,13 +1401,35 @@ bool llvm::isBuildVectorConstantSplat(const Register Reg,
return false;
}

bool llvm::isBuildVectorConstantSplat(const Register Reg,
const MachineRegisterInfo &MRI,
APInt SplatValue, bool AllowUndef) {
if (auto SplatValAndReg = getAnyConstantSplat(Reg, MRI, AllowUndef)) {
if (SplatValAndReg->Value.getBitWidth() < SplatValue.getBitWidth())
return APInt::isSameValue(
SplatValAndReg->Value.sext(SplatValue.getBitWidth()), SplatValue);
return APInt::isSameValue(
SplatValAndReg->Value,
SplatValue.sext(SplatValAndReg->Value.getBitWidth()));
}

return false;
}

bool llvm::isBuildVectorConstantSplat(const MachineInstr &MI,
const MachineRegisterInfo &MRI,
int64_t SplatValue, bool AllowUndef) {
return isBuildVectorConstantSplat(MI.getOperand(0).getReg(), MRI, SplatValue,
AllowUndef);
}

bool llvm::isBuildVectorConstantSplat(const MachineInstr &MI,
const MachineRegisterInfo &MRI,
APInt SplatValue, bool AllowUndef) {
return isBuildVectorConstantSplat(MI.getOperand(0).getReg(), MRI, SplatValue,
AllowUndef);
}

std::optional<APInt>
llvm::getIConstantSplatVal(const Register Reg, const MachineRegisterInfo &MRI) {
if (auto SplatValAndReg =
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40 changes: 40 additions & 0 deletions llvm/unittests/CodeGen/GlobalISel/PatternMatchTest.cpp
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Expand Up @@ -634,17 +634,25 @@ TEST_F(AArch64GISelMITest, MatchSpecificConstant) {
auto FortyTwo = B.buildConstant(LLT::scalar(64), 42);
EXPECT_TRUE(mi_match(FortyTwo.getReg(0), *MRI, m_SpecificICst(42)));
EXPECT_FALSE(mi_match(FortyTwo.getReg(0), *MRI, m_SpecificICst(123)));
EXPECT_TRUE(
mi_match(FortyTwo.getReg(0), *MRI, m_SpecificICst(APInt(64, 42))));
EXPECT_FALSE(
mi_match(FortyTwo.getReg(0), *MRI, m_SpecificICst(APInt(64, 123))));

// Test that this works inside of a more complex pattern.
LLT s64 = LLT::scalar(64);
auto MIBAdd = B.buildAdd(s64, Copies[0], FortyTwo);
EXPECT_TRUE(mi_match(MIBAdd.getReg(2), *MRI, m_SpecificICst(42)));
EXPECT_TRUE(mi_match(MIBAdd.getReg(2), *MRI, m_SpecificICst(APInt(64, 42))));

// Wrong constant.
EXPECT_FALSE(mi_match(MIBAdd.getReg(2), *MRI, m_SpecificICst(123)));
EXPECT_FALSE(
mi_match(MIBAdd.getReg(2), *MRI, m_SpecificICst(APInt(64, 123))));

// No constant on the LHS.
EXPECT_FALSE(mi_match(MIBAdd.getReg(1), *MRI, m_SpecificICst(42)));
EXPECT_FALSE(mi_match(MIBAdd.getReg(1), *MRI, m_SpecificICst(APInt(64, 42))));
}

TEST_F(AArch64GISelMITest, MatchSpecificConstantSplat) {
Expand All @@ -664,6 +672,13 @@ TEST_F(AArch64GISelMITest, MatchSpecificConstantSplat) {
mi_match(FortyTwoSplat.getReg(0), *MRI, m_SpecificICstSplat(43)));
EXPECT_FALSE(mi_match(FortyTwo.getReg(0), *MRI, m_SpecificICstSplat(42)));

EXPECT_TRUE(mi_match(FortyTwoSplat.getReg(0), *MRI,
m_SpecificICstSplat(APInt(64, 42))));
EXPECT_FALSE(mi_match(FortyTwoSplat.getReg(0), *MRI,
m_SpecificICstSplat(APInt(64, 43))));
EXPECT_FALSE(
mi_match(FortyTwo.getReg(0), *MRI, m_SpecificICstSplat(APInt(64, 42))));

MachineInstrBuilder NonConstantSplat =
B.buildBuildVector(v4s64, {Copies[0], Copies[0], Copies[0], Copies[0]});

Expand All @@ -673,8 +688,17 @@ TEST_F(AArch64GISelMITest, MatchSpecificConstantSplat) {
EXPECT_FALSE(mi_match(AddSplat.getReg(2), *MRI, m_SpecificICstSplat(43)));
EXPECT_FALSE(mi_match(AddSplat.getReg(1), *MRI, m_SpecificICstSplat(42)));

EXPECT_TRUE(
mi_match(AddSplat.getReg(2), *MRI, m_SpecificICstSplat(APInt(64, 42))));
EXPECT_FALSE(
mi_match(AddSplat.getReg(2), *MRI, m_SpecificICstSplat(APInt(64, 43))));
EXPECT_FALSE(
mi_match(AddSplat.getReg(1), *MRI, m_SpecificICstSplat(APInt(64, 42))));

MachineInstrBuilder Add = B.buildAdd(s64, Copies[0], FortyTwo);
EXPECT_FALSE(mi_match(Add.getReg(2), *MRI, m_SpecificICstSplat(42)));
EXPECT_FALSE(
mi_match(Add.getReg(2), *MRI, m_SpecificICstSplat(APInt(64, 42))));
}

TEST_F(AArch64GISelMITest, MatchSpecificConstantOrSplat) {
Expand All @@ -695,6 +719,13 @@ TEST_F(AArch64GISelMITest, MatchSpecificConstantOrSplat) {
mi_match(FortyTwoSplat.getReg(0), *MRI, m_SpecificICstOrSplat(43)));
EXPECT_TRUE(mi_match(FortyTwo.getReg(0), *MRI, m_SpecificICstOrSplat(42)));

EXPECT_TRUE(mi_match(FortyTwoSplat.getReg(0), *MRI,
m_SpecificICstOrSplat(APInt(64, 42))));
EXPECT_FALSE(mi_match(FortyTwoSplat.getReg(0), *MRI,
m_SpecificICstOrSplat(APInt(64, 43))));
EXPECT_TRUE(
mi_match(FortyTwo.getReg(0), *MRI, m_SpecificICstOrSplat(APInt(64, 42))));

MachineInstrBuilder NonConstantSplat =
B.buildBuildVector(v4s64, {Copies[0], Copies[0], Copies[0], Copies[0]});

Expand All @@ -704,8 +735,17 @@ TEST_F(AArch64GISelMITest, MatchSpecificConstantOrSplat) {
EXPECT_FALSE(mi_match(AddSplat.getReg(2), *MRI, m_SpecificICstOrSplat(43)));
EXPECT_FALSE(mi_match(AddSplat.getReg(1), *MRI, m_SpecificICstOrSplat(42)));

EXPECT_TRUE(
mi_match(AddSplat.getReg(2), *MRI, m_SpecificICstOrSplat(APInt(64, 42))));
EXPECT_FALSE(
mi_match(AddSplat.getReg(2), *MRI, m_SpecificICstOrSplat(APInt(64, 43))));
EXPECT_FALSE(
mi_match(AddSplat.getReg(1), *MRI, m_SpecificICstOrSplat(APInt(64, 42))));

MachineInstrBuilder Add = B.buildAdd(s64, Copies[0], FortyTwo);
EXPECT_TRUE(mi_match(Add.getReg(2), *MRI, m_SpecificICstOrSplat(42)));
EXPECT_TRUE(
mi_match(Add.getReg(2), *MRI, m_SpecificICstOrSplat(APInt(64, 42))));
}

TEST_F(AArch64GISelMITest, MatchZeroInt) {
Expand Down