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// SPDX-License-Identifier: GPL-3.0-or-later
#include "rcc/CodeGen/GlobalISel/CSEMIRBuilder.h"
#include "rcc/CodeGen/GenericOpcodes.h"
#include "rcc/CodeGen/GlobalISel/CSEInfo.h"
#include "rcc/CodeGen/MachineBasicBlock.h"
#include "rcc/CodeGen/MachineFunction.h"
#include "rcc/CodeGen/MachineInstr.h"
#include "rcc/CodeGen/MachineOperand.h"
#include "rcc/CodeGen/MachineRegisterInfo.h"
#include <algorithm>
#include <array>
#include <cstdint>
#include <limits>
#include <span>
#include <utility>
namespace rcc {
bool CSEMIRBuilder::canPerformCSE(Opcode InstructionOpcode) const noexcept {
const GISelCSEInfo *Info = getCSEInfo();
return Info != nullptr && Info->shouldCSE(InstructionOpcode);
}
bool CSEMIRBuilder::dominatesInsertionPoint(const MachineInstr &Instruction) const noexcept {
const MachineBasicBlock *Block = insertionBlock();
const MachineInstr *InsertBefore = insertionInstruction();
if (Block == nullptr || Instruction.parent() != Block)
return false;
if (InsertBefore == nullptr)
return true;
for (const MachineInstr *Current = Block->firstInstruction(); Current != nullptr;
Current = Current->next()) {
if (Current == &Instruction)
return true;
if (Current == InsertBefore)
return false;
}
return false;
}
Expected<void> CSEMIRBuilder::makeInstructionDominate(MachineInstr &Instruction) const {
MachineBasicBlock *Block = insertionBlock();
MachineInstr *InsertBefore = insertionInstruction();
if (Block == nullptr || Instruction.parent() != Block) {
return makeUnexpected(ErrorCode::InternalError,
"GlobalISel CSE candidate is not in the insertion block");
}
if (&Instruction == InsertBefore) {
return const_cast<CSEMIRBuilder *>(this)->setInsertPointAfter(Instruction);
}
if (InsertBefore == nullptr || dominatesInsertionPoint(Instruction))
return {};
auto Removed = Block->removeInstruction(Instruction);
if (!Removed)
return std::unexpected(Removed.error());
auto Inserted = Block->insertInstructionBefore(*InsertBefore, Instruction);
if (!Inserted)
return std::unexpected(Inserted.error());
return {};
}
Expected<MachineInstr *>
CSEMIRBuilder::generateCopyIfRequired(const MachineIRBuilderResult &Destination,
MachineInstr &Instruction) const {
if (Destination.kind() == MachineIRBuilderResult::Kind::Type)
return &Instruction;
const MachineOperand *Definition = Instruction.operandAt(0);
const Register *Source = Definition == nullptr ? nullptr : Definition->getIf<Register>();
if (Source == nullptr || !Definition->isDef()) {
return makeUnexpected(ErrorCode::InternalError,
"GlobalISel CSE candidate has no register definition");
}
if (Destination.reg() == *Source)
return &Instruction;
return MachineIRBuilder::buildCopy(Destination, *Source);
}
Expected<MachineInstr *> CSEMIRBuilder::memoize(MachineInstr &Instruction) const {
GISelCSEInfo *Info = getCSEInfo();
if (Info == nullptr)
return &Instruction;
auto Inserted = Info->handleRecordedInstruction(Instruction);
if (!Inserted)
return std::unexpected(Inserted.error());
return &Instruction;
}
Expected<MachineInstr *>
CSEMIRBuilder::buildInstr(Opcode InstructionOpcode,
std::span<const MachineIRBuilderResult> Destinations,
std::span<const Register> Sources) const {
if (!canPerformCSE(InstructionOpcode))
return MachineIRBuilder::buildInstr(InstructionOpcode, Destinations, Sources);
MachineBasicBlock *Block = insertionBlock();
if (Block == nullptr)
return makeUnexpected(ErrorCode::InvalidArgument, "machine IR builder has no insertion point");
GISelCSEInfo *Info = getCSEInfo();
const bool CanGenerateCopies =
Destinations.size() == 1 || std::ranges::all_of(Destinations, [](const auto &Destination) {
return Destination.kind() == MachineIRBuilderResult::Kind::Type;
});
if (!CanGenerateCopies) {
auto Built = MachineIRBuilder::buildInstr(InstructionOpcode, Destinations, Sources);
if (!Built)
return std::unexpected(Built.error());
Info->handleRemoveInstruction(**Built);
return *Built;
}
auto Existing =
Info->getMachineInstrIfExists(InstructionOpcode, Destinations, Sources,
std::span<const std::int64_t>(), MachineInstrFlags(), *Block);
if (!Existing)
return std::unexpected(Existing.error());
if (*Existing != nullptr) {
auto Dominating = makeInstructionDominate(**Existing);
if (!Dominating)
return std::unexpected(Dominating.error());
if (Destinations.size() == 1)
return generateCopyIfRequired(Destinations.front(), **Existing);
return *Existing;
}
auto Built = MachineIRBuilder::buildInstr(InstructionOpcode, Destinations, Sources);
if (!Built)
return std::unexpected(Built.error());
return memoize(**Built);
}
Expected<MachineInstr *> CSEMIRBuilder::buildConstant(MachineIRBuilderResult Destination,
APInt Value) const {
const Opcode ConstantOpcode = opcode(GenericOpcode::G_CONSTANT);
if (!canPerformCSE(ConstantOpcode))
return MachineIRBuilder::buildConstant(Destination, std::move(Value));
MachineBasicBlock *Block = insertionBlock();
if (Block == nullptr)
return makeUnexpected(ErrorCode::InvalidArgument, "machine IR builder has no insertion point");
GISelCSEInfo *Info = getCSEInfo();
auto Existing = Info->getConstantIfExists(Destination, Value, *Block);
if (!Existing)
return std::unexpected(Existing.error());
if (*Existing != nullptr) {
auto Dominating = makeInstructionDominate(**Existing);
if (!Dominating)
return std::unexpected(Dominating.error());
return generateCopyIfRequired(Destination, **Existing);
}
auto Built = MachineIRBuilder::buildConstant(Destination, std::move(Value));
if (!Built)
return std::unexpected(Built.error());
return memoize(**Built);
}
Expected<MachineInstr *> CSEMIRBuilder::buildSExtInReg(MachineIRBuilderResult Destination,
Register Source, std::uint32_t Width) const {
const Opcode InstructionOpcode = opcode(GenericOpcode::G_SEXT_INREG);
if (!canPerformCSE(InstructionOpcode))
return MachineIRBuilder::buildSExtInReg(Destination, Source, Width);
MachineBasicBlock *Block = insertionBlock();
if (Block == nullptr)
return makeUnexpected(ErrorCode::InvalidArgument, "machine IR builder has no insertion point");
GISelCSEInfo *Info = getCSEInfo();
const std::array Destinations{Destination};
const std::array Sources{Source};
const std::array Immediates{static_cast<std::int64_t>(Width)};
auto Existing = Info->getMachineInstrIfExists(
InstructionOpcode, std::span<const MachineIRBuilderResult>(Destinations),
std::span<const Register>(Sources), std::span<const std::int64_t>(Immediates),
MachineInstrFlags(), *Block);
if (!Existing)
return std::unexpected(Existing.error());
if (*Existing != nullptr) {
auto Dominating = makeInstructionDominate(**Existing);
if (!Dominating)
return std::unexpected(Dominating.error());
return generateCopyIfRequired(Destination, **Existing);
}
auto Built = MachineIRBuilder::buildSExtInReg(Destination, Source, Width);
if (!Built)
return std::unexpected(Built.error());
return memoize(**Built);
}
Expected<MachineInstr *> CSEMIRBuilder::buildExtract(MachineIRBuilderResult Destination,
Register Source, std::uint64_t Offset) const {
if (Offset > static_cast<std::uint64_t>(std::numeric_limits<std::int64_t>::max()))
return MachineIRBuilder::buildExtract(Destination, Source, Offset);
const Opcode InstructionOpcode = opcode(GenericOpcode::G_EXTRACT);
if (!canPerformCSE(InstructionOpcode))
return MachineIRBuilder::buildExtract(Destination, Source, Offset);
MachineBasicBlock *Block = insertionBlock();
if (Block == nullptr)
return makeUnexpected(ErrorCode::InvalidArgument, "machine IR builder has no insertion point");
GISelCSEInfo *Info = getCSEInfo();
const std::array Destinations{Destination};
const std::array Sources{Source};
const std::array Immediates{static_cast<std::int64_t>(Offset)};
auto Existing = Info->getMachineInstrIfExists(
InstructionOpcode, std::span<const MachineIRBuilderResult>(Destinations),
std::span<const Register>(Sources), std::span<const std::int64_t>(Immediates),
MachineInstrFlags(), *Block);
if (!Existing)
return std::unexpected(Existing.error());
if (*Existing != nullptr) {
auto Dominating = makeInstructionDominate(**Existing);
if (!Dominating)
return std::unexpected(Dominating.error());
return generateCopyIfRequired(Destination, **Existing);
}
auto Built = MachineIRBuilder::buildExtract(Destination, Source, Offset);
if (!Built)
return std::unexpected(Built.error());
return memoize(**Built);
}
} // namespace rcc
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