// SPDX-License-Identifier: GPL-3.0-or-later

#include "rcc/CodeGen/MachinePeepholeOptimizer.h"

#include "rcc/CodeGen/MachineBasicBlock.h"
#include "rcc/CodeGen/MachineFunction.h"
#include "rcc/CodeGen/MachineInstr.h"
#include "rcc/CodeGen/TargetDescription.h"
#include "rcc/CodeGen/TargetInstrInfo.h"

namespace rcc {
namespace {

[[nodiscard]] const MachinePassContract &peepholeOptimizerContract() {
  static const MachinePassContract Contract = [] {
    MachinePassContract Value{
        .Name = "peephole-opt",
        .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;
}

} // namespace

const MachinePassContract &MachinePeepholeOptimizerPass::contract() const noexcept {
  return peepholeOptimizerContract();
}

Expected<MachinePassResult> MachinePeepholeOptimizerPass::run(MachineFunction &Function,
                                                              const TargetDescription &Target,
                                                              MachineFunctionAnalysisManager &) {
  return runImplementation(Function, Target);
}

Expected<MachinePassResult>
MachinePeepholeOptimizerPass::runImplementation(MachineFunction &Function,
                                                const TargetDescription &Target) const {
  MachinePassResult Result;
  for (MachineBasicBlock *Block = Function.firstBlock(); Block != nullptr; Block = Block->next()) {
    for (MachineInstr *Instruction = Block->firstInstruction(); Instruction != nullptr;) {
      MachineInstr *Next = Instruction->next();
      if (!Instruction->isDebugInstr()) {
        auto Changed = Info->optimizeCondBranch(*Instruction, Function, Target);
        if (!Changed)
          return std::unexpected(Changed.error());
        Result.Changed |= *Changed;
      }
      Instruction = Next;
    }
  }
  if (Result.Changed) {
    Result.Changes = {MachinePassChange::Instructions, MachinePassChange::Operands,
                      MachinePassChange::Registers};
    Result.Preserved = PreservedAnalyses::none();
  } else {
    Result.Preserved = PreservedAnalyses::all();
  }
  return Result;
}

} // namespace rcc