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-rw-r--r--backend/lib/CodeGen/MachineCopyPropagation.cpp240
1 files changed, 107 insertions, 133 deletions
diff --git a/backend/lib/CodeGen/MachineCopyPropagation.cpp b/backend/lib/CodeGen/MachineCopyPropagation.cpp
index 2c4cc44..aafed4b 100644
--- a/backend/lib/CodeGen/MachineCopyPropagation.cpp
+++ b/backend/lib/CodeGen/MachineCopyPropagation.cpp
@@ -4,13 +4,11 @@
#include "rcc/CodeGen/GenericOpcodes.h"
#include "rcc/CodeGen/InstructionDescriptor.h"
-#include "rcc/CodeGen/LiveVariables.h"
#include "rcc/CodeGen/MachineBasicBlock.h"
#include "rcc/CodeGen/MachineFunction.h"
#include "rcc/CodeGen/MachineFunctionCloner.h"
#include "rcc/CodeGen/MachineInstr.h"
#include "rcc/CodeGen/MachineOperand.h"
-#include "rcc/CodeGen/MachineRegisterInfo.h"
#include "rcc/CodeGen/RegisterMask.h"
#include "rcc/CodeGen/TargetDescription.h"
#include "rcc/CodeGen/TargetInstrInfo.h"
@@ -20,46 +18,26 @@
#include <cstddef>
#include <optional>
#include <ranges>
-#include <string>
#include <utility>
-#include <vector>
namespace rcc {
namespace {
-[[nodiscard]] const MachinePassContract &
-copyPropagationContract(MachineCopyPropagationStage Stage) {
- static const MachinePassContract PreRA = [] {
+[[nodiscard]] const MachinePassContract &copyPropagationContract() {
+ static const MachinePassContract Contract = [] {
MachinePassContract Value{
- .Name = "pre-ra-machine-copy-propagation",
- .Requires = {MachineFunctionProperty::Selected, MachineFunctionProperty::NoPHIs,
- MachineFunctionProperty::TiedOpsRewritten},
+ .Name = "machine-cp",
+ .Requires = {MachineFunctionProperty::NoVRegs},
.Sets = {},
.Clears = {},
.RequiredAnalyses = {},
- .VerificationStage = PipelineStage::TiedOpsRewritten,
- };
- Value.ThreadSafety = PassThreadSafety::ThreadSafe;
- Value.DeclaredChanges = {MachinePassChange::Instructions, MachinePassChange::Operands,
- MachinePassChange::Registers};
- return Value;
- }();
- static const MachinePassContract PostRA = [] {
- MachinePassContract Value{
- .Name = "post-ra-machine-copy-propagation",
- .Requires = {MachineFunctionProperty::Selected, MachineFunctionProperty::NoPHIs,
- MachineFunctionProperty::TiedOpsRewritten, MachineFunctionProperty::NoVRegs,
- MachineFunctionProperty::TracksLiveness},
- .Sets = {},
- .Clears = {},
- .RequiredAnalyses = {},
- .VerificationStage = PipelineStage::RegisterAllocated,
+ .VerificationStage = std::nullopt,
};
Value.ThreadSafety = PassThreadSafety::ThreadSafe;
Value.DeclaredChanges = {MachinePassChange::Instructions, MachinePassChange::Operands};
return Value;
}();
- return Stage == MachineCopyPropagationStage::PreRegisterAllocation ? PreRA : PostRA;
+ return Contract;
}
[[nodiscard]] bool hasProtectedAttachment(const MachineInstr &Instruction) noexcept {
@@ -78,13 +56,25 @@ struct CopyOperands final {
Register Source;
};
-[[nodiscard]] std::optional<CopyOperands> copyOperands(MachineInstr &Instruction) {
- if (Instruction.opcode() != opcode(GenericOpcode::COPY) || Instruction.operandCount() != 2 ||
- hasProtectedAttachment(Instruction)) {
+[[nodiscard]] std::optional<CopyOperands> copyOperands(MachineInstr &Instruction,
+ const TargetInstrInfo &Info,
+ bool UseTargetCopyInstructions) {
+ if (hasProtectedAttachment(Instruction))
return std::nullopt;
+ MachineOperand *DestinationOperand = nullptr;
+ MachineOperand *SourceOperand = nullptr;
+ if (UseTargetCopyInstructions) {
+ const std::optional<MachineCopyOperands> TargetCopy = Info.getCopyOperands(Instruction);
+ if (!TargetCopy)
+ return std::nullopt;
+ DestinationOperand = TargetCopy->Destination;
+ SourceOperand = TargetCopy->Source;
+ } else {
+ if (Instruction.opcode() != opcode(GenericOpcode::COPY) || Instruction.operandCount() < 2)
+ return std::nullopt;
+ DestinationOperand = Instruction.operandAt(0);
+ SourceOperand = Instruction.operandAt(1);
}
- MachineOperand *DestinationOperand = Instruction.operandAt(0);
- MachineOperand *SourceOperand = Instruction.operandAt(1);
const Register *Destination =
DestinationOperand == nullptr ? nullptr : DestinationOperand->getIf<Register>();
const Register *Source = SourceOperand == nullptr ? nullptr : SourceOperand->getIf<Register>();
@@ -95,88 +85,6 @@ struct CopyOperands final {
return CopyOperands{DestinationOperand, SourceOperand, *Destination, *Source};
}
-[[nodiscard]] Expected<bool> compatibleVirtualRegisters(Register Destination, Register Source,
- const MachineFunction &Function,
- const TargetDescription &Target) {
- if (!Destination.isVirtual() || !Source.isVirtual())
- return false;
- auto DestinationInfo = Function.registerInfo().virtualRegisterInfo(Destination);
- auto SourceInfo = Function.registerInfo().virtualRegisterInfo(Source);
- if (!DestinationInfo || !SourceInfo)
- return std::unexpected(!DestinationInfo ? DestinationInfo.error() : SourceInfo.error());
- const VirtualRegisterInfo &DestinationValue = DestinationInfo->get();
- const VirtualRegisterInfo &SourceValue = SourceInfo->get();
- if (DestinationValue.Type != SourceValue.Type)
- return false;
- if (DestinationValue.Bank && SourceValue.Bank &&
- !Target.registers().registerBanksOverlap(*DestinationValue.Bank, *SourceValue.Bank)) {
- return false;
- }
- if (DestinationValue.RegClass && SourceValue.RegClass &&
- !Target.registers().isSubclass(*SourceValue.RegClass, *DestinationValue.RegClass)) {
- return false;
- }
- return true;
-}
-
-[[nodiscard]] Expected<bool> propagateVirtualCopy(MachineInstr &Copy, const CopyOperands &Operands,
- MachineFunction &Function,
- const TargetDescription &Target,
- const TargetInstrInfo &Info) {
- if (!Operands.Destination.isVirtual() || !Operands.Source.isVirtual())
- return false;
- if (Function.registerInfo().getUniqueVRegDef(Operands.Destination) !=
- Operands.DestinationOperand) {
- return false;
- }
- auto Compatible =
- compatibleVirtualRegisters(Operands.Destination, Operands.Source, Function, Target);
- if (!Compatible)
- return std::unexpected(Compatible.error());
- if (!*Compatible)
- return false;
- auto ValidCopy =
- Info.validateCopy(Operands.Destination, Operands.DestinationOperand->subReg(),
- Operands.Source, Operands.SourceOperand->subReg(), Function, Target);
- if (!ValidCopy) {
- if (ValidCopy.error().code() == ErrorCode::Unsupported)
- return false;
- return std::unexpected(ValidCopy.error());
- }
-
- std::vector<MachineOperand *> Uses;
- for (MachineOperand &Use : Function.registerInfo().useOperands(Operands.Destination, true)) {
- if (&Use == Operands.SourceOperand)
- continue;
- if (Use.tiedOperandIndex() || Use.isImplicit() ||
- Use.subReg() != Operands.DestinationOperand->subReg()) {
- return false;
- }
- Uses.push_back(&Use);
- }
- for (MachineOperand *Use : Uses) {
- auto Replaced = Use->setRegister(Operands.Source);
- if (!Replaced)
- return std::unexpected(Replaced.error());
- }
- MachineBasicBlock *Block = Copy.parent();
- if (Block == nullptr)
- return makeUnexpected(ErrorCode::InternalError,
- "virtual COPY propagation candidate is detached");
- auto Removed = Block->removeInstruction(Copy);
- if (!Removed)
- return std::unexpected(Removed.error());
- if (!Function.registerInfo().useEmpty(Operands.Destination, true) ||
- Function.registerInfo().getUniqueVRegDef(Operands.Destination) != nullptr) {
- return makeUnexpected(ErrorCode::InternalError,
- "virtual COPY propagation left destination references");
- }
- auto Erased = Function.registerInfo().eraseVirtualRegister(Operands.Destination);
- if (!Erased)
- return std::unexpected(Erased.error());
- return true;
-}
-
[[nodiscard]] bool shareRegisterClass(PhysicalRegister Left, PhysicalRegister Right,
const TargetRegisterInfo &Registers) noexcept {
return std::ranges::any_of(Registers.registerClasses(), [&](const RegisterClassDesc &Class) {
@@ -203,8 +111,9 @@ struct CopyOperands final {
}
[[nodiscard]] bool canReplacePhysicalUse(const MachineInstr &Instruction, std::size_t OperandIndex,
- PhysicalRegister Source,
- const TargetDescription &Target) noexcept {
+ PhysicalRegister Source, const MachineFunction &Function,
+ const TargetDescription &Target,
+ const TargetInstrInfo &Info) noexcept {
const MachineOperand *Operand = Instruction.operandAt(OperandIndex);
const InstructionDescriptor *Descriptor = Target.instructionDescriptor(Instruction.opcode());
if (Operand == nullptr || Descriptor == nullptr || Operand->isImplicit() ||
@@ -220,9 +129,57 @@ struct CopyOperands final {
if (Constraint.RegBank && !Target.registers().bankContainsRegister(*Constraint.RegBank, Source)) {
return false;
}
+ if (Instruction.opcode() == opcode(GenericOpcode::COPY)) {
+ const MachineOperand *DestinationOperand = Instruction.operandAt(0);
+ const Register *Destination =
+ DestinationOperand == nullptr ? nullptr : DestinationOperand->getIf<Register>();
+ if (Destination == nullptr)
+ return false;
+ auto Valid =
+ Info.validateCopy(*Destination, DestinationOperand->subReg(),
+ Register::fromPhysical(Source), Operand->subReg(), Function, Target);
+ if (!Valid)
+ return false;
+ }
return true;
}
+[[nodiscard]] bool valueUsedAfter(const MachineInstr &Copy, PhysicalRegister Destination,
+ const TargetDescription &Target) noexcept {
+ for (const MachineInstr *Instruction = Copy.next(); Instruction != nullptr;
+ Instruction = Instruction->next()) {
+ for (const MachineOperand &Operand : Instruction->operands()) {
+ if (const auto *Mask = Operand.getIf<RegisterMaskOperand>()) {
+ if (Mask->Mask && Mask->Mask->clobbers(Destination))
+ return false;
+ continue;
+ }
+ const Register *Reg = Operand.getIf<Register>();
+ const std::optional<PhysicalRegister> Physical =
+ Reg == nullptr ? std::nullopt : Reg->physicalRegister();
+ if (!Physical || !Target.registers().regsOverlap(*Physical, Destination))
+ continue;
+ if (Operand.isUse())
+ return true;
+ if (Operand.isDef())
+ return false;
+ }
+ }
+ const MachineBasicBlock *Block = Copy.parent();
+ if (Block == nullptr)
+ return true;
+ if (!Block->successors().empty() &&
+ !Copy.function().properties().has(MachineFunctionProperty::TracksLiveness)) {
+ return true;
+ }
+ return std::ranges::any_of(Block->successors(), [&](const MachineSuccessor &Successor) {
+ return Successor.Block != nullptr &&
+ std::ranges::any_of(Successor.Block->liveIns(), [&](const MachineBasicBlockLiveIn &In) {
+ return Target.registers().regsOverlap(In.PhysReg, Destination);
+ });
+ });
+}
+
[[nodiscard]] Expected<bool> propagatePhysicalCopy(MachineInstr &Copy, const CopyOperands &Operands,
MachineFunction &Function,
const TargetDescription &Target,
@@ -244,7 +201,8 @@ struct CopyOperands final {
if (Block == nullptr)
return makeUnexpected(ErrorCode::InternalError,
"physical COPY propagation candidate is detached");
- if (*Destination == *Source) {
+ const bool IsGenericCopy = Copy.opcode() == opcode(GenericOpcode::COPY);
+ if (*Destination == *Source && IsGenericCopy) {
auto Removed = Block->removeInstruction(Copy);
if (!Removed)
return std::unexpected(Removed.error());
@@ -265,24 +223,43 @@ struct CopyOperands final {
const Register *Reg = Operand == nullptr ? nullptr : Operand->getIf<Register>();
const std::optional<PhysicalRegister> Physical =
Reg == nullptr ? std::nullopt : Reg->physicalRegister();
- if (!Physical || !Operand->isUse() || Operand->isDebugUse() ||
- !Target.registers().regsOverlap(*Physical, *Destination) ||
- !canReplacePhysicalUse(*Instruction, Index, *Source, Target)) {
+ if (!Physical || *Physical != *Destination || !Operand->isUse() || Operand->isDebugUse() ||
+ !Operand->registerFlags().has(RegisterOperandFlag::Renamable) ||
+ !canReplacePhysicalUse(*Instruction, Index, *Source, Function, Target, Info)) {
continue;
}
auto Replaced = Operand->setRegister(Operands.Source);
if (!Replaced)
return std::unexpected(Replaced.error());
+ RegisterOperandFlags Flags = Operand->registerFlags();
+ Flags.clear(RegisterOperandFlag::Kill);
+ if (!Operands.SourceOperand->registerFlags().has(RegisterOperandFlag::Renamable))
+ Flags.clear(RegisterOperandFlag::Renamable);
+ if (Operands.SourceOperand->registerFlags().has(RegisterOperandFlag::Undef))
+ Flags.set(RegisterOperandFlag::Undef);
+ else
+ Flags.clear(RegisterOperandFlag::Undef);
+ auto SetFlags = Operand->setRegisterFlags(Flags);
+ if (!SetFlags)
+ return std::unexpected(SetFlags.error());
Changed = true;
}
}
+ if (IsGenericCopy &&
+ Operands.DestinationOperand->registerFlags().has(RegisterOperandFlag::Renamable) &&
+ !valueUsedAfter(Copy, *Destination, Target)) {
+ auto Removed = Block->removeInstruction(Copy);
+ if (!Removed)
+ return std::unexpected(Removed.error());
+ Changed = true;
+ }
return Changed;
}
} // namespace
const MachinePassContract &MachineCopyPropagationPass::contract() const noexcept {
- return copyPropagationContract(Stage);
+ return copyPropagationContract();
}
Expected<MachinePassResult>
@@ -325,7 +302,13 @@ MachineCopyPropagationPass::runImplementation(MachineFunction &Function,
for (MachineInstr *Instruction = Block->firstInstruction();
Instruction != nullptr && PropagatedCopies < Options.MaximumPropagatedCopies;) {
MachineInstr *Next = Instruction->next();
- const std::optional<CopyOperands> Operands = copyOperands(*Instruction);
+ auto Simplified = Info->simplifyInstruction(*Instruction, Function, Target);
+ if (!Simplified)
+ return std::unexpected(Simplified.error());
+ if (*Simplified)
+ Result.Changed = true;
+ const std::optional<CopyOperands> Operands =
+ copyOperands(*Instruction, *Info, Options.UseTargetCopyInstructions);
if (!Operands) {
Instruction = Next;
continue;
@@ -338,9 +321,7 @@ MachineCopyPropagationPass::runImplementation(MachineFunction &Function,
continue;
}
Expected<bool> Changed =
- Stage == MachineCopyPropagationStage::PreRegisterAllocation
- ? propagateVirtualCopy(*Instruction, *Operands, Function, Target, *Info)
- : propagatePhysicalCopy(*Instruction, *Operands, Function, Target, *Info);
+ propagatePhysicalCopy(*Instruction, *Operands, Function, Target, *Info);
if (!Changed)
return std::unexpected(Changed.error());
if (*Changed) {
@@ -355,14 +336,7 @@ MachineCopyPropagationPass::runImplementation(MachineFunction &Function,
Result.Preserved = PreservedAnalyses::all();
return Result;
}
- if (Function.properties().has(MachineFunctionProperty::TracksLiveness)) {
- auto Rebuilt = rebuildMachineLiveness(Function, Target);
- if (!Rebuilt)
- return std::unexpected(Rebuilt.error());
- }
Result.Changes = {MachinePassChange::Instructions, MachinePassChange::Operands};
- if (Stage == MachineCopyPropagationStage::PreRegisterAllocation)
- Result.Changes.add(MachinePassChange::Registers);
Result.Preserved = PreservedAnalyses::none();
return Result;
}
generated by cgit v1.2.3 (git 2.46.0) at 2026-10-29 05:41:45 +0000