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[GISel] Introduce MachineIRBuilder::(build|materialize)ObjectPtrOffset #150392

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Jul 29, 2025
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[GISel] Introduce MachineIRBuilder::(build|materialize)ObjectPtrOffset #150392

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42 changes: 38 additions & 4 deletions llvm/include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
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Original file line number Diff line number Diff line change
Expand Up @@ -518,6 +518,21 @@ class LLVM_ABI MachineIRBuilder {
const SrcOp &Op1,
std::optional<unsigned> Flags = std::nullopt);

/// Build and insert an instruction with appropriate flags for addressing some
/// offset of an object, i.e.: \p Res = nuw G_PTR_ADD \p Op0, \p Op1
/// The value of \p Op0 must be a pointer into or just after an object, adding
/// the value of \p Op1 to it must yield to a pointer into or just after the
/// same object.
///
/// \pre setBasicBlock or setMI must have been called.
/// \pre \p Res and \p Op0 must be generic virtual registers with pointer
/// type.
/// \pre \p Op1 must be a generic virtual register with scalar type.
///
/// \return a MachineInstrBuilder for the newly created instruction.
MachineInstrBuilder buildObjectPtrOffset(const DstOp &Res, const SrcOp &Op0,
const SrcOp &Op1);

/// Materialize and insert \p Res = G_PTR_ADD \p Op0, (G_CONSTANT \p Value)
///
/// G_PTR_ADD adds \p Value bytes to the pointer specified by \p Op0,
Expand All @@ -534,10 +549,29 @@ class LLVM_ABI MachineIRBuilder {
/// type as \p Op0 or \p Op0 itself.
///
/// \return a MachineInstrBuilder for the newly created instruction.
std::optional<MachineInstrBuilder> materializePtrAdd(Register &Res,
Register Op0,
const LLT ValueTy,
uint64_t Value);
std::optional<MachineInstrBuilder>
materializePtrAdd(Register &Res, Register Op0, const LLT ValueTy,
uint64_t Value,
std::optional<unsigned> Flags = std::nullopt);

/// Materialize and insert an instruction with appropriate flags for
/// addressing some offset of an object, i.e.:
/// \p Res = nuw G_PTR_ADD \p Op0, (G_CONSTANT \p Value)
/// The value of \p Op0 must be a pointer into or just after an object, adding
/// \p Value to it must yield to a pointer into or just after the same object.
///
/// \pre setBasicBlock or setMI must have been called.
/// \pre \p Op0 must be a generic virtual register with pointer type.
/// \pre \p ValueTy must be a scalar type.
/// \pre \p Res must be 0. This is to detect confusion between
/// materializeObjectPtrOffset() and buildObjectPtrOffset().
/// \post \p Res will either be a new generic virtual register of the same
/// type as \p Op0 or \p Op0 itself.
///
/// \return a MachineInstrBuilder for the newly created instruction.
std::optional<MachineInstrBuilder>
materializeObjectPtrOffset(Register &Res, Register Op0, const LLT ValueTy,
uint64_t Value);

/// Build and insert \p Res = G_PTRMASK \p Op0, \p Op1
MachineInstrBuilder buildPtrMask(const DstOp &Res, const SrcOp &Op0,
Expand Down
6 changes: 4 additions & 2 deletions llvm/lib/CodeGen/GlobalISel/CallLowering.cpp
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Expand Up @@ -1009,7 +1009,8 @@ void CallLowering::insertSRetLoads(MachineIRBuilder &MIRBuilder, Type *RetTy,

for (unsigned I = 0; I < NumValues; ++I) {
Register Addr;
MIRBuilder.materializePtrAdd(Addr, DemoteReg, OffsetLLTy, Offsets[I]);
MIRBuilder.materializeObjectPtrOffset(Addr, DemoteReg, OffsetLLTy,
Offsets[I]);
auto *MMO = MF.getMachineMemOperand(PtrInfo, MachineMemOperand::MOLoad,
MRI.getType(VRegs[I]),
commonAlignment(BaseAlign, Offsets[I]));
Expand Down Expand Up @@ -1039,7 +1040,8 @@ void CallLowering::insertSRetStores(MachineIRBuilder &MIRBuilder, Type *RetTy,

for (unsigned I = 0; I < NumValues; ++I) {
Register Addr;
MIRBuilder.materializePtrAdd(Addr, DemoteReg, OffsetLLTy, Offsets[I]);
MIRBuilder.materializeObjectPtrOffset(Addr, DemoteReg, OffsetLLTy,
Offsets[I]);
auto *MMO = MF.getMachineMemOperand(PtrInfo, MachineMemOperand::MOStore,
MRI.getType(VRegs[I]),
commonAlignment(BaseAlign, Offsets[I]));
Expand Down
4 changes: 2 additions & 2 deletions llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
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Expand Up @@ -1409,7 +1409,7 @@ bool IRTranslator::translateLoad(const User &U, MachineIRBuilder &MIRBuilder) {
Regs.size() == 1 ? LI.getMetadata(LLVMContext::MD_range) : nullptr;
for (unsigned i = 0; i < Regs.size(); ++i) {
Register Addr;
MIRBuilder.materializePtrAdd(Addr, Base, OffsetTy, Offsets[i] / 8);
MIRBuilder.materializeObjectPtrOffset(Addr, Base, OffsetTy, Offsets[i] / 8);

MachinePointerInfo Ptr(LI.getPointerOperand(), Offsets[i] / 8);
Align BaseAlign = getMemOpAlign(LI);
Expand Down Expand Up @@ -1448,7 +1448,7 @@ bool IRTranslator::translateStore(const User &U, MachineIRBuilder &MIRBuilder) {

for (unsigned i = 0; i < Vals.size(); ++i) {
Register Addr;
MIRBuilder.materializePtrAdd(Addr, Base, OffsetTy, Offsets[i] / 8);
MIRBuilder.materializeObjectPtrOffset(Addr, Base, OffsetTy, Offsets[i] / 8);

MachinePointerInfo Ptr(SI.getPointerOperand(), Offsets[i] / 8);
Align BaseAlign = getMemOpAlign(SI);
Expand Down
18 changes: 9 additions & 9 deletions llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
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Expand Up @@ -4170,7 +4170,7 @@ LegalizerHelper::LegalizeResult LegalizerHelper::lowerLoad(GAnyLoad &LoadMI) {
auto OffsetCst = MIRBuilder.buildConstant(LLT::scalar(PtrTy.getSizeInBits()),
LargeSplitSize / 8);
Register PtrAddReg = MRI.createGenericVirtualRegister(PtrTy);
auto SmallPtr = MIRBuilder.buildPtrAdd(PtrAddReg, PtrReg, OffsetCst);
auto SmallPtr = MIRBuilder.buildObjectPtrOffset(PtrAddReg, PtrReg, OffsetCst);
auto SmallLoad = MIRBuilder.buildLoadInstr(LoadMI.getOpcode(), AnyExtTy,
SmallPtr, *SmallMMO);

Expand Down Expand Up @@ -4277,8 +4277,7 @@ LegalizerHelper::LegalizeResult LegalizerHelper::lowerStore(GStore &StoreMI) {
LLT PtrTy = MRI.getType(PtrReg);
auto OffsetCst = MIRBuilder.buildConstant(
LLT::scalar(PtrTy.getSizeInBits()), LargeSplitSize / 8);
auto SmallPtr =
MIRBuilder.buildPtrAdd(PtrTy, PtrReg, OffsetCst);
auto SmallPtr = MIRBuilder.buildObjectPtrOffset(PtrTy, PtrReg, OffsetCst);

MachineMemOperand *LargeMMO =
MF.getMachineMemOperand(&MMO, 0, LargeSplitSize / 8);
Expand Down Expand Up @@ -5349,7 +5348,8 @@ LegalizerHelper::reduceLoadStoreWidth(GLoadStore &LdStMI, unsigned TypeIdx,
unsigned ByteOffset = Offset / 8;
Register NewAddrReg;

MIRBuilder.materializePtrAdd(NewAddrReg, AddrReg, OffsetTy, ByteOffset);
MIRBuilder.materializeObjectPtrOffset(NewAddrReg, AddrReg, OffsetTy,
ByteOffset);

MachineMemOperand *NewMMO =
MF.getMachineMemOperand(&MMO, ByteOffset, PartTy);
Expand Down Expand Up @@ -9822,7 +9822,7 @@ LegalizerHelper::lowerMemset(MachineInstr &MI, Register Dst, Register Val,
if (DstOff != 0) {
auto Offset =
MIB.buildConstant(LLT::scalar(PtrTy.getSizeInBits()), DstOff);
Ptr = MIB.buildPtrAdd(PtrTy, Dst, Offset).getReg(0);
Ptr = MIB.buildObjectPtrOffset(PtrTy, Dst, Offset).getReg(0);
}

MIB.buildStore(Value, Ptr, *StoreMMO);
Expand Down Expand Up @@ -9962,15 +9962,15 @@ LegalizerHelper::lowerMemcpy(MachineInstr &MI, Register Dst, Register Src,
LLT SrcTy = MRI.getType(Src);
Offset = MIB.buildConstant(LLT::scalar(SrcTy.getSizeInBits()), CurrOffset)
.getReg(0);
LoadPtr = MIB.buildPtrAdd(SrcTy, Src, Offset).getReg(0);
LoadPtr = MIB.buildObjectPtrOffset(SrcTy, Src, Offset).getReg(0);
}
auto LdVal = MIB.buildLoad(CopyTy, LoadPtr, *LoadMMO);

// Create the store.
Register StorePtr = Dst;
if (CurrOffset != 0) {
LLT DstTy = MRI.getType(Dst);
StorePtr = MIB.buildPtrAdd(DstTy, Dst, Offset).getReg(0);
StorePtr = MIB.buildObjectPtrOffset(DstTy, Dst, Offset).getReg(0);
}
MIB.buildStore(LdVal, StorePtr, *StoreMMO);
CurrOffset += CopyTy.getSizeInBytes();
Expand Down Expand Up @@ -10060,7 +10060,7 @@ LegalizerHelper::lowerMemmove(MachineInstr &MI, Register Dst, Register Src,
LLT SrcTy = MRI.getType(Src);
auto Offset =
MIB.buildConstant(LLT::scalar(SrcTy.getSizeInBits()), CurrOffset);
LoadPtr = MIB.buildPtrAdd(SrcTy, Src, Offset).getReg(0);
LoadPtr = MIB.buildObjectPtrOffset(SrcTy, Src, Offset).getReg(0);
}
LoadVals.push_back(MIB.buildLoad(CopyTy, LoadPtr, *LoadMMO).getReg(0));
CurrOffset += CopyTy.getSizeInBytes();
Expand All @@ -10078,7 +10078,7 @@ LegalizerHelper::lowerMemmove(MachineInstr &MI, Register Dst, Register Src,
LLT DstTy = MRI.getType(Dst);
auto Offset =
MIB.buildConstant(LLT::scalar(DstTy.getSizeInBits()), CurrOffset);
StorePtr = MIB.buildPtrAdd(DstTy, Dst, Offset).getReg(0);
StorePtr = MIB.buildObjectPtrOffset(DstTy, Dst, Offset).getReg(0);
}
MIB.buildStore(LoadVals[I], StorePtr, *StoreMMO);
CurrOffset += CopyTy.getSizeInBytes();
Expand Down
19 changes: 16 additions & 3 deletions llvm/lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
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Expand Up @@ -208,11 +208,18 @@ MachineIRBuilder::buildPtrAdd(const DstOp &Res, const SrcOp &Op0,
return buildInstr(TargetOpcode::G_PTR_ADD, {Res}, {Op0, Op1}, Flags);
}

MachineInstrBuilder MachineIRBuilder::buildObjectPtrOffset(const DstOp &Res,
const SrcOp &Op0,
const SrcOp &Op1) {
return buildPtrAdd(Res, Op0, Op1, MachineInstr::MIFlag::NoUWrap);
}

std::optional<MachineInstrBuilder>
MachineIRBuilder::materializePtrAdd(Register &Res, Register Op0,
const LLT ValueTy, uint64_t Value) {
const LLT ValueTy, uint64_t Value,
std::optional<unsigned> Flags) {
assert(Res == 0 && "Res is a result argument");
assert(ValueTy.isScalar() && "invalid offset type");
assert(ValueTy.isScalar() && "invalid offset type");

if (Value == 0) {
Res = Op0;
Expand All @@ -221,7 +228,13 @@ MachineIRBuilder::materializePtrAdd(Register &Res, Register Op0,

Res = getMRI()->createGenericVirtualRegister(getMRI()->getType(Op0));
auto Cst = buildConstant(ValueTy, Value);
return buildPtrAdd(Res, Op0, Cst.getReg(0));
return buildPtrAdd(Res, Op0, Cst.getReg(0), Flags);
}

std::optional<MachineInstrBuilder> MachineIRBuilder::materializeObjectPtrOffset(
Register &Res, Register Op0, const LLT ValueTy, uint64_t Value) {
return materializePtrAdd(Res, Op0, ValueTy, Value,
MachineInstr::MIFlag::NoUWrap);
}

MachineInstrBuilder MachineIRBuilder::buildMaskLowPtrBits(const DstOp &Res,
Expand Down
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