//===- CIRGenModule.cpp - Per-Module state for CIR generation -------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This is the internal per-translation-unit state used for CIR translation.
//
//===----------------------------------------------------------------------===//

#include "CIRGenModule.h"

#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclBase.h"
#include "clang/AST/GlobalDecl.h"
#include "clang/Basic/SourceManager.h"
#include "clang/CIR/Dialect/IR/CIRDialect.h"

#include "mlir/IR/BuiltinOps.h"
#include "mlir/IR/Location.h"
#include "mlir/IR/MLIRContext.h"

using namespace clang;
using namespace clang::CIRGen;

CIRGenModule::CIRGenModule(mlir::MLIRContext &context,
                           clang::ASTContext &astctx,
                           const clang::CodeGenOptions &cgo,
                           DiagnosticsEngine &diags)
    : builder(&context), astCtx(astctx), langOpts(astctx.getLangOpts()),
      theModule{mlir::ModuleOp::create(mlir::UnknownLoc::get(&context))},
      diags(diags), target(astCtx.getTargetInfo()) {}

mlir::Location CIRGenModule::getLoc(SourceLocation cLoc) {
  assert(cLoc.isValid() && "expected valid source location");
  const SourceManager &sm = astCtx.getSourceManager();
  PresumedLoc pLoc = sm.getPresumedLoc(cLoc);
  StringRef filename = pLoc.getFilename();
  return mlir::FileLineColLoc::get(builder.getStringAttr(filename),
                                   pLoc.getLine(), pLoc.getColumn());
}

mlir::Location CIRGenModule::getLoc(SourceRange cRange) {
  assert(cRange.isValid() && "expected a valid source range");
  mlir::Location begin = getLoc(cRange.getBegin());
  mlir::Location end = getLoc(cRange.getEnd());
  mlir::Attribute metadata;
  return mlir::FusedLoc::get({begin, end}, metadata, builder.getContext());
}

void CIRGenModule::buildGlobal(clang::GlobalDecl gd) {
  const auto *global = cast<ValueDecl>(gd.getDecl());

  if (const auto *fd = dyn_cast<FunctionDecl>(global)) {
    // Update deferred annotations with the latest declaration if the function
    // was already used or defined.
    if (fd->hasAttr<AnnotateAttr>())
      errorNYI(fd->getSourceRange(), "deferredAnnotations");
    if (!fd->doesThisDeclarationHaveABody()) {
      if (!fd->doesDeclarationForceExternallyVisibleDefinition())
        return;

      errorNYI(fd->getSourceRange(),
               "function declaration that forces code gen");
      return;
    }
  } else {
    errorNYI(global->getSourceRange(), "global variable declaration");
  }

  // TODO(CIR): Defer emitting some global definitions until later
  buildGlobalDefinition(gd);
}

void CIRGenModule::buildGlobalFunctionDefinition(clang::GlobalDecl gd,
                                                 mlir::Operation *op) {
  auto const *funcDecl = cast<FunctionDecl>(gd.getDecl());
  auto funcOp = builder.create<cir::FuncOp>(
      getLoc(funcDecl->getSourceRange()), funcDecl->getIdentifier()->getName());
  theModule.push_back(funcOp);
}

void CIRGenModule::buildGlobalDefinition(clang::GlobalDecl gd,
                                         mlir::Operation *op) {
  const auto *decl = cast<ValueDecl>(gd.getDecl());
  if (const auto *fd = dyn_cast<FunctionDecl>(decl)) {
    // TODO(CIR): Skip generation of CIR for functions with available_externally
    // linkage at -O0.

    if (const auto *method = dyn_cast<CXXMethodDecl>(decl)) {
      // Make sure to emit the definition(s) before we emit the thunks. This is
      // necessary for the generation of certain thunks.
      (void)method;
      errorNYI(method->getSourceRange(), "member function");
      return;
    }

    if (fd->isMultiVersion())
      errorNYI(fd->getSourceRange(), "multiversion functions");
    buildGlobalFunctionDefinition(gd, op);
    return;
  }

  llvm_unreachable("Invalid argument to CIRGenModule::buildGlobalDefinition");
}

// Emit code for a single top level declaration.
void CIRGenModule::buildTopLevelDecl(Decl *decl) {

  // Ignore dependent declarations.
  if (decl->isTemplated())
    return;

  switch (decl->getKind()) {
  default:
    errorNYI(decl->getBeginLoc(), "declaration of kind",
             decl->getDeclKindName());
    break;

  case Decl::Function: {
    auto *fd = cast<FunctionDecl>(decl);
    // Consteval functions shouldn't be emitted.
    if (!fd->isConsteval())
      buildGlobal(fd);
    break;
  }
  }
}

DiagnosticBuilder CIRGenModule::errorNYI(llvm::StringRef feature) {
  unsigned diagID = diags.getCustomDiagID(
      DiagnosticsEngine::Error, "ClangIR code gen Not Yet Implemented: %0");
  return diags.Report(diagID) << feature;
}

DiagnosticBuilder CIRGenModule::errorNYI(SourceLocation loc,
                                         llvm::StringRef feature) {
  unsigned diagID = diags.getCustomDiagID(
      DiagnosticsEngine::Error, "ClangIR code gen Not Yet Implemented: %0");
  return diags.Report(loc, diagID) << feature;
}

DiagnosticBuilder CIRGenModule::errorNYI(SourceLocation loc,
                                         llvm::StringRef feature,
                                         llvm::StringRef name) {
  unsigned diagID = diags.getCustomDiagID(
      DiagnosticsEngine::Error, "ClangIR code gen Not Yet Implemented: %0: %1");
  return diags.Report(loc, diagID) << feature << name;
}

DiagnosticBuilder CIRGenModule::errorNYI(SourceRange loc,
                                         llvm::StringRef feature) {
  return errorNYI(loc.getBegin(), feature) << loc;
}

DiagnosticBuilder CIRGenModule::errorNYI(SourceRange loc,
                                         llvm::StringRef feature,
                                         llvm::StringRef name) {
  return errorNYI(loc.getBegin(), feature, name) << loc;
}