//===--- Context.cpp - Context for the constexpr VM -------------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

#include "Context.h"

#include "ByteCodeEmitter.h"

#include "ByteCodeExprGen.h"

#include "ByteCodeStmtGen.h"

#include "EvalEmitter.h"

#include "Interp.h"

#include "InterpFrame.h"

#include "InterpStack.h"

#include "PrimType.h"

#include "Program.h"

#include "clang/AST/Expr.h"

#include "clang/Basic/TargetInfo.h"

using namespace clang;

using namespace clang::interp;

Context::Context(ASTContext &Ctx) : Ctx(Ctx), P(new Program(*this)) {}

Context::~Context() {}

bool Context::isPotentialConstantExpr(State &Parent, const FunctionDecl *FD) {

  Function *Func = P->getFunction(FD);

  if (!Func) {

    if (auto R = ByteCodeStmtGen<ByteCodeEmitter>(*this, *P).compileFunc(FD)) {

      Func = *R;

    } else {

      handleAllErrors(R.takeError(), [&Parent](ByteCodeGenError &Err) {

        Parent.FFDiag(Err.getLoc(), diag::err_experimental_clang_interp_failed);

      });

      return false;

    }

  }

  if (!Func->isConstexpr())

    return false;

  APValue Dummy;

  return Run(Parent, Func, Dummy);

}

bool Context::evaluateAsRValue(State &Parent, const Expr *E, APValue &Result) {

  ByteCodeExprGen<EvalEmitter> C(*this, *P, Parent, Stk, Result);

  return Check(Parent, C.interpretExpr(E));

}

bool Context::evaluateAsInitializer(State &Parent, const VarDecl *VD,

                                    APValue &Result) {

  ByteCodeExprGen<EvalEmitter> C(*this, *P, Parent, Stk, Result);

  return Check(Parent, C.interpretDecl(VD));

}

const LangOptions &Context::getLangOpts() const { return Ctx.getLangOpts(); }

llvm::Optional<PrimType> Context::classify(QualType T) {

  if (T->isReferenceType() || T->isPointerType()) {

    return PT_Ptr;

  }

  if (T->isBooleanType())

    return PT_Bool;

  if (T->isSignedIntegerOrEnumerationType()) {

    switch (Ctx.getIntWidth(T)) {

    case 64:

      return PT_Sint64;

    case 32:

      return PT_Sint32;

    case 16:

      return PT_Sint16;

    case 8:

      return PT_Sint8;

    default:

      return {};

    }

  }

  if (T->isUnsignedIntegerOrEnumerationType()) {

    switch (Ctx.getIntWidth(T)) {

    case 64:

      return PT_Uint64;

    case 32:

      return PT_Uint32;

    case 16:

      return PT_Uint16;

    case 8:

      return PT_Uint8;

    default:

      return {};

    }

  }

  if (T->isNullPtrType())

    return PT_Ptr;

  if (auto *AT = dyn_cast<AtomicType>(T))

    return classify(AT->getValueType());

  return {};

}

unsigned Context::getCharBit() const {

  return Ctx.getTargetInfo().getCharWidth();

}

bool Context::Run(State &Parent, Function *Func, APValue &Result) {

  InterpState State(Parent, *P, Stk, *this);

  State.Current = new InterpFrame(State, Func, nullptr, {}, {});

  if (Interpret(State, Result))

    return true;

  Stk.clear();

  return false;

}

bool Context::Check(State &Parent, llvm::Expected<bool> &&Flag) {

  if (Flag)

    return *Flag;

  handleAllErrors(Flag.takeError(), [&Parent](ByteCodeGenError &Err) {

    Parent.FFDiag(Err.getLoc(), diag::err_experimental_clang_interp_failed);

  });

  return false;

}