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// SPDX-License-Identifier: GPL-3.0-or-later
#include "rcc/CodeGen/MachineCombiner.h"
#include "rcc/CodeGen/MachineBasicBlock.h"
#include "rcc/CodeGen/MachineFunction.h"
#include "rcc/CodeGen/MachineIRBuilder.h"
#include "rcc/CodeGen/MachineInstr.h"
#include "rcc/CodeGen/MachineOperand.h"
#include "rcc/CodeGen/MachineRegisterInfo.h"
#include "rcc/CodeGen/TargetDescription.h"
#include <cstddef>
#include <cstdint>
#include <string>
namespace rcc {
namespace {
[[nodiscard]] const MachinePassContract &combinerContract() {
static const MachinePassContract Contract = [] {
MachinePassContract Value{
.Name = "machine-combiner",
.Requires = {MachineFunctionProperty::IsSSA},
.Sets = {},
.Clears = {},
.RequiredAnalyses = {},
.VerificationStage = PipelineStage::Selected,
};
Value.ThreadSafety = PassThreadSafety::ThreadSafe;
Value.DeclaredChanges = {MachinePassChange::Instructions, MachinePassChange::Operands,
MachinePassChange::Registers};
return Value;
}();
return Contract;
}
[[nodiscard]] bool hasProtectedAttachment(const MachineInstr &Instruction) noexcept {
return Instruction.flags().has(MachineInstrFlag::FrameSetup) ||
Instruction.flags().has(MachineInstrFlag::FrameDestroy) ||
Instruction.debugInstrNumber() != 0 || Instruction.preInstrSymbol().has_value() ||
Instruction.postInstrSymbol().has_value() || Instruction.heapAllocMarker().has_value() ||
Instruction.pcSections().has_value() || Instruction.mmra().has_value() ||
Instruction.cfiType().has_value() || Instruction.deactivationSymbol().has_value();
}
[[nodiscard]] MachineInstrFlags intersectFlags(MachineInstrFlags Left,
MachineInstrFlags Right) noexcept {
MachineInstrFlags Result;
for (std::uint32_t Index = 0; Index < static_cast<std::uint32_t>(MachineInstrFlag::Count);
++Index) {
const auto Flag = static_cast<MachineInstrFlag>(Index);
if (Left.has(Flag) && Right.has(Flag))
Result.set(Flag);
}
return Result;
}
[[nodiscard]] bool hasEqualRoundingMode(const MachineInstr &Root,
const MachineInstr &Producer) noexcept {
const MachineOperand *RootMode = Root.operandAt(3);
const MachineOperand *ProducerMode = Producer.operandAt(3);
const auto *RootImmediate = RootMode == nullptr ? nullptr : RootMode->getIf<std::int64_t>();
const auto *ProducerImmediate =
ProducerMode == nullptr ? nullptr : ProducerMode->getIf<std::int64_t>();
return RootImmediate != nullptr && ProducerImmediate != nullptr &&
*RootImmediate == *ProducerImmediate;
}
[[nodiscard]] MachineInstr *findProducer(MachineInstr &Root,
const MachineCombinerPattern &Pattern) noexcept {
const MachineOperand *ProducerUse = Root.operandAt(Pattern.ProducerOperand);
const Register *ProducerRegister =
ProducerUse == nullptr ? nullptr : ProducerUse->getIf<Register>();
if (ProducerRegister == nullptr || !ProducerUse->isUse() || !ProducerRegister->isVirtual()) {
return nullptr;
}
MachineInstr *Producer = Root.function().registerInfo().getVRegDef(*ProducerRegister);
if (Producer == nullptr || Producer->opcode() != Pattern.ProducerOpcode ||
Producer->parent() != Root.parent() || Producer->operandCount() < 4 ||
hasProtectedAttachment(*Producer)) {
return nullptr;
}
const MachineOperand *Definition = Producer->operandAt(0);
const Register *DefinedRegister = Definition == nullptr ? nullptr : Definition->getIf<Register>();
if (DefinedRegister == nullptr || !Definition->isDef() || Definition->isUse() ||
*DefinedRegister != *ProducerRegister) {
return nullptr;
}
if (!Root.flags().has(MachineInstrFlag::FastMathAllowContract) ||
!Producer->flags().has(MachineInstrFlag::FastMathAllowContract) ||
!hasEqualRoundingMode(Root, *Producer)) {
return nullptr;
}
return Producer;
}
[[nodiscard]] Expected<void> clearKillFlags(MachineRegisterInfo &Registers, Register Reg) {
for (MachineOperand &Operand : Registers.regOperands(Reg)) {
RegisterOperandFlags Flags = Operand.registerFlags();
if (!Flags.has(RegisterOperandFlag::Kill))
continue;
Flags.clear(RegisterOperandFlag::Kill);
auto Changed = Operand.setRegisterFlags(Flags);
if (!Changed)
return std::unexpected(Changed.error());
}
return {};
}
[[nodiscard]] Expected<bool> combineFusedMultiplyAdd(MachineInstr &Root, MachineInstr &Producer,
const MachineCombinerPattern &Pattern,
MachineFunction &Function,
const TargetDescription &Target) {
const MachineOperand *RootDefinition = Root.operandAt(0);
const MachineOperand *MultiplyLeft = Producer.operandAt(1);
const MachineOperand *MultiplyRight = Producer.operandAt(2);
const MachineOperand *Addend = Root.operandAt(Pattern.AddendOperand);
const Register *ProducerResult = Producer.operandAt(0)->getIf<Register>();
const Register *MultiplyLeftRegister =
MultiplyLeft == nullptr ? nullptr : MultiplyLeft->getIf<Register>();
const Register *MultiplyRightRegister =
MultiplyRight == nullptr ? nullptr : MultiplyRight->getIf<Register>();
if (RootDefinition == nullptr || MultiplyLeftRegister == nullptr ||
MultiplyRightRegister == nullptr || Addend == nullptr || ProducerResult == nullptr) {
return false;
}
MachineRegisterInfo &Registers = Function.registerInfo();
const bool EraseProducer = Registers.hasOneUse(*ProducerResult, false);
auto Cleared = clearKillFlags(Registers, *MultiplyLeftRegister);
if (!Cleared)
return std::unexpected(Cleared.error());
Cleared = clearKillFlags(Registers, *MultiplyRightRegister);
if (!Cleared)
return std::unexpected(Cleared.error());
MachineIRBuilder Builder(Function, Target);
auto Point = Builder.setInsertPointBefore(Root);
if (!Point)
return std::unexpected(Point.error());
auto Pending = Builder.buildInstr(Pattern.ReplacementOpcode);
if (!Pending)
return std::unexpected(Pending.error());
auto Added = Pending->addOperand(RootDefinition->cloneDetached());
if (!Added)
return std::unexpected(Added.error());
Added = Pending->addOperand(MultiplyLeft->cloneDetached());
if (!Added)
return std::unexpected(Added.error());
Added = Pending->addOperand(MultiplyRight->cloneDetached());
if (!Added)
return std::unexpected(Added.error());
Added = Pending->addOperand(Addend->cloneDetached());
if (!Added)
return std::unexpected(Added.error());
Added = Pending->addOperand(Root.operandAt(3)->cloneDetached());
if (!Added)
return std::unexpected(Added.error());
for (std::size_t Index = 4; Index < Root.operandCount(); ++Index) {
Added = Pending->addImplicitOperand(Root.operandAt(Index)->cloneDetached());
if (!Added)
return std::unexpected(Added.error());
}
Added = Pending->setFlags(intersectFlags(Root.flags(), Producer.flags()));
if (!Added)
return std::unexpected(Added.error());
if (Root.debugLocation()) {
Added = Pending->setDebugLocation(*Root.debugLocation());
if (!Added)
return std::unexpected(Added.error());
}
auto Fused = Pending->build();
if (!Fused)
return std::unexpected(Fused.error());
auto Removed = Root.eraseFromParent();
if (!Removed)
return std::unexpected(Removed.error());
if (EraseProducer) {
Removed = Producer.eraseFromParent();
if (!Removed)
return std::unexpected(Removed.error());
}
return true;
}
} // namespace
const MachinePassContract &MachineCombinerPass::contract() const noexcept {
return combinerContract();
}
Expected<MachinePassResult> MachineCombinerPass::run(MachineFunction &Function,
const TargetDescription &Target,
MachineFunctionAnalysisManager &Analyses) {
return runImplementation(Function, Target, Analyses);
}
Expected<MachinePassResult>
MachineCombinerPass::runImplementation(MachineFunction &Function, const TargetDescription &Target,
MachineFunctionAnalysisManager &Analyses) const {
if (Options.MaximumIterations == 0)
return makeUnexpected(ErrorCode::InvalidArgument,
"machine combiner iteration budget must be nonzero");
MachinePassResult Result;
std::size_t Rewrites = 0;
for (std::size_t Iteration = 0; Iteration < Options.MaximumIterations; ++Iteration) {
bool IterationChanged = false;
for (MachineBasicBlock *Block = Function.firstBlock(); Block != nullptr;
Block = Block->next()) {
for (MachineInstr *Instruction = Block->firstInstruction(); Instruction != nullptr;) {
MachineInstr *Next = Instruction->next();
for (const MachineCombinerPattern &Pattern : Info->patterns(Instruction->opcode())) {
if (Rewrites == Options.MaximumRewrites)
break;
if (hasProtectedAttachment(*Instruction) || Instruction->operandCount() < 4)
continue;
MachineInstr *Producer = findProducer(*Instruction, Pattern);
if (Producer == nullptr)
continue;
std::string Rule = "combine.";
Rule.append(Pattern.Name);
auto Accepted = Analyses.requestAction(Rule, Function, Instruction->stableID());
if (!Accepted)
return std::unexpected(Accepted.error());
if (!*Accepted)
continue;
auto Executed =
combineFusedMultiplyAdd(*Instruction, *Producer, Pattern, Function, Target);
if (!Executed)
return std::unexpected(Executed.error());
if (!*Executed)
continue;
++Rewrites;
IterationChanged = true;
Result.Changed = true;
break;
}
Instruction = Next;
}
}
if (!IterationChanged || Rewrites == Options.MaximumRewrites)
break;
}
if (!Result.Changed) {
Result.Preserved = PreservedAnalyses::all();
return Result;
}
Result.Changes = {MachinePassChange::Instructions, MachinePassChange::Operands,
MachinePassChange::Registers};
Result.Preserved = PreservedAnalyses::none();
return Result;
}
} // namespace rcc
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