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// SPDX-License-Identifier: GPL-3.0-or-later
#include "rcc/CodeGen/MacroFusion.h"
#include "rcc/CodeGen/InstructionDescriptor.h"
#include "rcc/CodeGen/MachineFunction.h"
#include "rcc/CodeGen/MachineInstr.h"
#include "rcc/CodeGen/MachineOperand.h"
#include "rcc/CodeGen/MachineRegisterInfo.h"
#include "rcc/CodeGen/ScheduleDAG.h"
#include "rcc/CodeGen/TargetDescription.h"
#include <algorithm>
#include <cstddef>
#include <iostream>
#include <optional>
#include <ranges>
#include <span>
#include <vector>
namespace rcc {
namespace {
[[nodiscard]] const MachineInstr *instructionFor(MacroFusionInstruction Side,
const MachineInstr *First,
const MachineInstr &Second) noexcept {
return Side == MacroFusionInstruction::First ? First : &Second;
}
[[nodiscard]] std::optional<Register> registerAt(const MachineInstr &Instruction,
std::uint32_t OperandIndex) noexcept {
const MachineOperand *Operand = Instruction.operandAt(OperandIndex);
return Operand == nullptr ? std::nullopt : Operand->registerValue();
}
[[nodiscard]] const std::int64_t *immediateAt(const MachineInstr &Instruction,
std::uint32_t OperandIndex) noexcept {
const MachineOperand *Operand = Instruction.operandAt(OperandIndex);
return Operand == nullptr ? nullptr : Operand->getIf<std::int64_t>();
}
[[nodiscard]] bool containsOpcode(std::span<const Opcode> Opcodes, Opcode Value) noexcept {
return std::ranges::contains(Opcodes, Value);
}
[[nodiscard]] bool matchesLink(const MacroFusionRule &Rule, const MachineInstr &First,
const MachineInstr &Second) noexcept {
const std::optional<Register> FirstDefinition = registerAt(First, Rule.FirstDefinitionOperand);
const std::optional<Register> SecondUse = registerAt(Second, Rule.SecondUseOperand);
const std::optional<Register> AlternateSecondUse =
Rule.CommutableSecondUseOperand == MacroFusionRule::NoOperand
? std::nullopt
: registerAt(Second, Rule.CommutableSecondUseOperand);
if (!FirstDefinition ||
(*FirstDefinition != SecondUse && *FirstDefinition != AlternateSecondUse)) {
return false;
}
if (Rule.RequireSingleNonDebugUse && FirstDefinition->isVirtual() &&
!Second.function().registerInfo().hasOneUse(*FirstDefinition, false)) {
return false;
}
if (!Rule.RequireSecondDestinationTie)
return true;
const std::optional<Register> SecondDefinition = registerAt(Second, Rule.SecondDefinitionOperand);
if (!SecondDefinition || SecondDefinition->isVirtual())
return SecondDefinition.has_value();
return *SecondDefinition == SecondUse || *SecondDefinition == AlternateSecondUse;
}
[[nodiscard]] bool isFusionCandidateDependency(ScheduleDependencyKind Kind) noexcept {
return Kind != ScheduleDependencyKind::Anti && Kind != ScheduleDependencyKind::Output &&
Kind != ScheduleDependencyKind::Cluster;
}
[[nodiscard]] std::string_view opcodeName(const TargetDescription &Target, Opcode Value) noexcept {
const InstructionDescriptor *Descriptor = Target.instructionDescriptor(Value);
return Descriptor == nullptr ? std::string_view{"<unknown>"} : Descriptor->Name;
}
} // namespace
bool matchesMacroFusion(const MacroFusionRule &Rule, const MachineInstr *First,
const MachineInstr &Second) noexcept {
if (!containsOpcode(Rule.SecondOpcodes, Second.opcode()))
return false;
if (First == nullptr)
return true;
if (!containsOpcode(Rule.FirstOpcodes, First->opcode()))
return false;
if (!Rule.OpcodePairs.empty() &&
std::ranges::none_of(Rule.OpcodePairs, [First, &Second](MacroFusionOpcodePair Pair) {
return Pair.First == First->opcode() && Pair.Second == Second.opcode();
})) {
return false;
}
for (const MacroFusionImmediatePredicate &Predicate : Rule.ImmediatePredicates) {
const MachineInstr *Instruction = instructionFor(Predicate.Instruction, First, Second);
const std::int64_t *Value =
Instruction == nullptr ? nullptr : immediateAt(*Instruction, Predicate.OperandIndex);
if (Value == nullptr || *Value < Predicate.Minimum || *Value > Predicate.Maximum)
return false;
}
for (const MacroFusionRegisterInequality &Predicate : Rule.RegisterInequalities) {
const MachineInstr *Instruction = instructionFor(Predicate.Instruction, First, Second);
if (Instruction == nullptr)
return false;
const std::optional<Register> Left = registerAt(*Instruction, Predicate.LeftOperand);
const std::optional<Register> Right = registerAt(*Instruction, Predicate.RightOperand);
if (!Left || !Right || *Left == *Right)
return false;
}
for (const MacroFusionImmediateRelation &Predicate : Rule.ImmediateRelations) {
const std::int64_t *FirstValue = immediateAt(*First, Predicate.FirstOperand);
const std::int64_t *SecondValue = immediateAt(Second, Predicate.SecondOperand);
if (FirstValue == nullptr || SecondValue == nullptr || *FirstValue > *SecondValue)
return false;
}
return matchesLink(Rule, *First, Second);
}
Expected<void> applyMacroFusion(ScheduleDAG &DAG, std::span<const MacroFusionRule> Rules,
const TargetDescription &Target, bool EmitDebugOutput) {
if (Rules.empty())
return {};
for (ScheduleUnit &Anchor : DAG.units()) {
if (Anchor.Instructions.size() != 1 || Anchor.ClusterPredecessor || Anchor.ClusterSuccessor)
continue;
const MachineInstr &Second = *Anchor.Instructions.front();
if (std::ranges::none_of(Rules, [&Second](const MacroFusionRule &Rule) {
return matchesMacroFusion(Rule, nullptr, Second);
})) {
continue;
}
const std::vector<ScheduleDependency> Predecessors = Anchor.Predecessors;
for (const ScheduleDependency &Dependency : Predecessors) {
if (!isFusionCandidateDependency(Dependency.Kind))
continue;
const ScheduleUnit *FirstUnit = DAG.unit(Dependency.Source);
if (FirstUnit == nullptr || FirstUnit->Instructions.size() != 1 ||
FirstUnit->ClusterPredecessor || FirstUnit->ClusterSuccessor) {
continue;
}
const MachineInstr &First = *FirstUnit->Instructions.front();
if (std::ranges::none_of(Rules, [&First, &Second](const MacroFusionRule &Rule) {
return matchesMacroFusion(Rule, &First, Second);
})) {
continue;
}
auto Fused = DAG.fuseInstructionPair(FirstUnit->ID, Anchor.ID);
if (!Fused)
return std::unexpected(Fused.error());
if (!*Fused)
continue;
if (EmitDebugOutput) {
std::cerr << "Macro fuse: SU(" << FirstUnit->ID << ") - SU(" << Anchor.ID << ") / "
<< opcodeName(Target, First.opcode()) << " - "
<< opcodeName(Target, Second.opcode()) << '\n';
}
break;
}
}
return {};
}
} // namespace rcc
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