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// SPDX-License-Identifier: GPL-3.0-or-later
#include "rcc/CodeGen/PrologueEpilogueInsertion.h"
#include "rcc/CodeGen/FrameIndexElimination.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/MachineMemOperand.h"
#include "rcc/CodeGen/MachineOperand.h"
#include "rcc/CodeGen/MachineVerifier.h"
#include "rcc/CodeGen/RegisterScavenger.h"
#include "rcc/CodeGen/TargetFrameLowering.h"
#include <string>
#include <utility>
#include <vector>
namespace rcc {
namespace {} // namespace
const MachinePassContract &PrologueEpilogueInsertionPass::contract() const noexcept {
static const MachinePassContract Contract = [] {
MachinePassContract Value{
.Name = "prologepilog",
.Requires = {MachineFunctionProperty::NoPHIs, MachineFunctionProperty::NoVRegs},
.Sets = {MachineFunctionProperty::FrameFinalized, MachineFunctionProperty::NoFrameIndices},
.Clears = {},
.RequiredAnalyses = {},
.VerificationStage = PipelineStage::FrameFinalized,
};
Value.ThreadSafety = PassThreadSafety::ThreadSafe;
Value.DeclaredChanges = {MachinePassChange::Instructions, MachinePassChange::Operands,
MachinePassChange::Registers, MachinePassChange::Frame};
return Value;
}();
return Contract;
}
Expected<MachinePassResult> PrologueEpilogueInsertionPass::run(MachineFunction &Function,
const TargetDescription &Target,
MachineFunctionAnalysisManager &) {
if (Info == nullptr)
return makeUnexpected(ErrorCode::InvalidArgument,
"PrologueEpilogueInsertion requires target frame lowering");
const MachineFunctionProperties Missing = contract().Requires.missingFrom(Function.properties());
if (!Missing.empty()) {
return makeUnexpected(ErrorCode::VerificationError,
"PrologueEpilogueInsertion requires properties: " + Missing.toString());
}
auto Trial = cloneMachineFunction(
Function, Target,
MachineFunctionCloneOptions{.NewStableID = Function.stableID(), .NewName = std::nullopt});
if (!Trial)
return std::unexpected(withErrorContext(Trial.error(), "frame transaction setup failed: "));
auto TrialRun = runImplementation(*Trial->ClonedFunction, Target);
if (!TrialRun)
return std::unexpected(
withErrorContext(TrialRun.error(), "frame transaction rejected input: "));
auto Transition = Trial->ClonedFunction->properties().applyTransition(
contract().Requires, contract().Sets, contract().Clears);
if (!Transition) {
return std::unexpected(
withErrorContext(Transition.error(), "frame transaction property update failed: "));
}
auto Verified =
MachineVerifier::verify(*Trial->ClonedFunction, Target,
MachineVerifierOptions{.Mode = MachineVerifierMode::Generic,
.Stage = contract().VerificationStage,
.VerifyProperties = true});
if (!Verified) {
return std::unexpected(
withErrorContext(Verified.error(), "frame transaction postcondition failed: "));
}
auto Result = runImplementation(Function, Target);
if (!Result) {
return std::unexpected(withErrorContext(
Result.error(), "frame lowering diverged after successful transaction preflight: "));
}
return Result;
}
Expected<MachinePassResult>
PrologueEpilogueInsertionPass::runImplementation(MachineFunction &Function,
const TargetDescription &Target) const {
auto Prepared = Info->prepareFrame(Function, Target);
if (!Prepared)
return std::unexpected(Prepared.error());
RegisterScavenger Scavenger(Function, Target);
std::vector<MachineInstr *> CallFramePseudos;
std::vector<std::pair<MachineBasicBlock *, MachineInstr *>> Epilogues;
for (MachineBasicBlock *Block = Function.firstBlock(); Block != nullptr; Block = Block->next()) {
for (MachineInstr *Instruction = Block->firstInstruction(); Instruction != nullptr;
Instruction = Instruction->next()) {
if (Info->isCallFramePseudo(*Instruction))
CallFramePseudos.push_back(Instruction);
if (Info->isEpilogueTerminator(*Instruction, Target))
Epilogues.emplace_back(Block, Instruction);
}
}
for (MachineInstr *Pseudo : CallFramePseudos) {
auto Eliminated = Info->eliminateCallFramePseudo(*Pseudo, Function, Target, Scavenger);
if (!Eliminated)
return std::unexpected(Eliminated.error());
}
auto CalleeSaved = Info->insertCalleeSavedSpillsAndRestores(Function, Target);
if (!CalleeSaved)
return std::unexpected(CalleeSaved.error());
auto PreFinalized = Info->processFunctionBeforeFrameFinalized(Function, Target);
if (!PreFinalized)
return std::unexpected(PreFinalized.error());
auto Finalized = Info->finalizeFrame(Function, Target);
if (!Finalized)
return std::unexpected(Finalized.error());
if (!Function.frameInfo().isFrozen()) {
return makeUnexpected(ErrorCode::InternalError,
"target frame lowering did not freeze the frame layout");
}
auto Prologue = Info->emitPrologue(Function, Target, Scavenger);
if (!Prologue)
return std::unexpected(Prologue.error());
for (const auto &[Block, Terminator] : Epilogues) {
auto Epilogue = Info->emitEpilogue(*Block, *Terminator, Function, Target, Scavenger);
if (!Epilogue)
return std::unexpected(Epilogue.error());
}
auto PreFrameIndices = Info->processFunctionBeforeFrameIndexElimination(Function, Target);
if (!PreFrameIndices)
return std::unexpected(PreFrameIndices.error());
auto FrameIndices = eliminateFrameIndices(Function, Target, *Info, Scavenger);
if (!FrameIndices)
return std::unexpected(FrameIndices.error());
if (Function.properties().has(MachineFunctionProperty::TracksLiveness)) {
auto Rebuilt = rebuildMachineLiveness(Function, Target);
if (!Rebuilt)
return std::unexpected(Rebuilt.error());
}
MachinePassResult Result;
Result.Changed = true;
Result.Changes = {MachinePassChange::Instructions, MachinePassChange::Operands,
MachinePassChange::Registers, MachinePassChange::Frame};
Result.Preserved = PreservedAnalyses::none();
return Result;
}
} // namespace rcc
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