CIRGenerator.cpp

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//===--- CIRGenerator.cpp - Emit CIR from ASTs ----------------------------===//
//
// 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 builds an AST and converts it to CIR.
//
//===----------------------------------------------------------------------===//
 
#include "CIRGenModule.h"
 
#include "mlir/Dialect/Arith/IR/Arith.h"
#include "mlir/Dialect/DLTI/DLTI.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/Dialect/OpenACC/OpenACC.h"
#include "mlir/Dialect/OpenMP/OpenMPDialect.h"
#include "mlir/IR/MLIRContext.h"
 
#include "clang/AST/DeclGroup.h"
#include "clang/AST/DeclOpenACC.h"
#include "clang/AST/GlobalDecl.h"
#include "clang/CIR/CIRDataLayoutSpec.h"
#include "clang/CIR/CIRGenerator.h"
#include "clang/CIR/InitAllDialects.h"
#include "clang/CIR/MissingFeatures.h"
#include "llvm/IR/DataLayout.h"
 
using namespace cir;
using namespace clang;
 
void CIRGenerator::anchor() {}
 
CIRGenerator::CIRGenerator(clang::DiagnosticsEngine &diags,
                           llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> vfs,
                           const CodeGenOptions &cgo)
    : diags(diags), fs(std::move(vfs)), codeGenOpts{cgo},
      handlingTopLevelDecls{0} {}
CIRGenerator::~CIRGenerator() {
  // There should normally not be any leftover inline method definitions.
  assert(deferredInlineMemberFuncDefs.empty() || diags.hasErrorOccurred());
}
 
void CIRGenerator::Initialize(ASTContext &astContext) {
  using namespace llvm;
 
  this->astContext = &astContext;
 
  mlirContext = std::make_unique<mlir::MLIRContext>();
  // MLIR multithreading stays enabled; the CIRDiagnosticHandler is only ever
  // invoked from a single thread.
  cir::registerAllDialects(*mlirContext);
  mlirContext->loadDialect<mlir::DLTIDialect, mlir::LLVM::LLVMDialect,
                           cir::CIRDialect>();
  const LangOptions &langOpts = astContext.getLangOpts();
  // OpenACC lowering emits Arith constants for bounds and clause operands.
  if (langOpts.OpenACC)
    mlirContext
        ->loadDialect<mlir::acc::OpenACCDialect, mlir::arith::ArithDialect>();
  if (langOpts.OpenMP)
    mlirContext->getOrLoadDialect<mlir::omp::OpenMPDialect>();
 
  cgm = std::make_unique<clang::CIRGen::CIRGenModule>(
      *mlirContext.get(), astContext, codeGenOpts, diags);
  mlir::ModuleOp mod = cgm->getModule();
  llvm::DataLayout layout =
      llvm::DataLayout(astContext.getTargetInfo().getDataLayoutString());
  cir::setMLIRDataLayout(mod, layout);
}
 
bool CIRGenerator::verifyModule() const { return cgm->verifyModule(); }
 
mlir::ModuleOp CIRGenerator::getModule() const { return cgm->getModule(); }
 
const Decl *CIRGenerator::getDeclForMangledName(llvm::StringRef mangledName) {
  GlobalDecl result;
  if (!cgm->lookupRepresentativeDecl(mangledName, result))
    return nullptr;
  const Decl *decl = result.getCanonicalDecl().getDecl();
  if (auto *fd = dyn_cast<FunctionDecl>(decl)) {
    if (fd->hasBody(fd))
      return fd;
  } else if (auto *td = dyn_cast<TagDecl>(decl)) {
    if (auto *def = td->getDefinition())
      return def;
  }
  return decl;
}
 
bool CIRGenerator::HandleTopLevelDecl(DeclGroupRef group) {
  if (diags.hasUnrecoverableErrorOccurred())
    return true;
 
  HandlingTopLevelDeclRAII handlingDecl(*this);
 
  for (Decl *decl : group)
    cgm->emitTopLevelDecl(decl);
 
  return true;
}
 
void CIRGenerator::HandleTranslationUnit(ASTContext &astContext) {
  // Release the Builder when there is no error.
  if (!diags.hasErrorOccurred() && cgm)
    cgm->release();
 
  // If there are errors before or when releasing the cgm, reset the module to
  // stop here before invoking the backend.
  assert(!cir::MissingFeatures::cleanupAfterErrorDiags());
}
 
void CIRGenerator::HandleInlineFunctionDefinition(FunctionDecl *d) {
  if (diags.hasErrorOccurred())
    return;
 
  assert(d->doesThisDeclarationHaveABody());
 
  // We may want to emit this definition. However, that decision might be
  // based on computing the linkage, and we have to defer that in case we are
  // inside of something that will chagne the method's final linkage, e.g.
  //   typedef struct {
  //     void bar();
  //     void foo() { bar(); }
  //   } A;
  deferredInlineMemberFuncDefs.push_back(d);
 
  // Provide some coverage mapping even for methods that aren't emitted.
  // Don't do this for templated classes though, as they may not be
  // instantiable.
  assert(!cir::MissingFeatures::coverageMapping());
}
 
void CIRGenerator::emitDeferredDecls() {
  if (deferredInlineMemberFuncDefs.empty())
    return;
 
  // Emit any deferred inline method definitions. Note that more deferred
  // methods may be added during this loop, since ASTConsumer callbacks can be
  // invoked if AST inspection results in declarations being added. Therefore,
  // we use an index to loop over the deferredInlineMemberFuncDefs rather than
  // a range.
  HandlingTopLevelDeclRAII handlingDecls(*this);
  for (unsigned i = 0; i != deferredInlineMemberFuncDefs.size(); ++i)
    cgm->emitTopLevelDecl(deferredInlineMemberFuncDefs[i]);
  deferredInlineMemberFuncDefs.clear();
}
 
/// HandleTagDeclDefinition - This callback is invoked each time a TagDecl to
/// (e.g. struct, union, enum, class) is completed. This allows the client to
/// hack on the type, which can occur at any point in the file (because these
/// can be defined in declspecs).
void CIRGenerator::HandleTagDeclDefinition(TagDecl *d) {
  if (diags.hasErrorOccurred())
    return;
 
  // Don't allow re-entrant calls to CIRGen triggered by PCH deserialization to
  // emit deferred decls.
  HandlingTopLevelDeclRAII handlingDecl(*this, /*EmitDeferred=*/false);
 
  cgm->updateCompletedType(d);
 
  // For MSVC compatibility, treat declarations of static data members with
  // inline initializers as definitions.
  if (astContext->getTargetInfo().getCXXABI().isMicrosoft())
    cgm->errorNYI(d->getSourceRange(), "HandleTagDeclDefinition: MSABI");
 
  // For OpenMP emit declare reduction functions or declare mapper, if
  // required.
  if (astContext->getLangOpts().OpenMP) {
    for (Decl *member : d->decls()) {
      if (auto *drd = dyn_cast<OMPDeclareReductionDecl>(member)) {
        if (astContext->DeclMustBeEmitted(drd))
          cgm->errorNYI(d->getSourceRange(),
                        "HandleTagDeclDefinition: OMPDeclareReductionDecl");
      } else if (auto *dmd = dyn_cast<OMPDeclareMapperDecl>(member)) {
        if (astContext->DeclMustBeEmitted(dmd))
          cgm->errorNYI(d->getSourceRange(),
                        "HandleTagDeclDefinition: OMPDeclareMapperDecl");
      }
    }
  }
}
 
void CIRGenerator::HandleTagDeclRequiredDefinition(const TagDecl *D) {
  if (diags.hasErrorOccurred())
    return;
 
  assert(!cir::MissingFeatures::generateDebugInfo());
}
 
void CIRGenerator::HandleCXXStaticMemberVarInstantiation(VarDecl *D) {
  if (diags.hasErrorOccurred())
    return;
 
  cgm->handleCXXStaticMemberVarInstantiation(D);
}
 
void CIRGenerator::HandleOpenACCRoutineReference(const FunctionDecl *FD,
                                                 const OpenACCRoutineDecl *RD) {
  llvm::StringRef mangledName = cgm->getMangledName(FD);
  cir::FuncOp entry =
      mlir::dyn_cast_if_present<cir::FuncOp>(cgm->getGlobalValue(mangledName));
 
  // if this wasn't generated, don't force it to be.
  if (!entry)
    return;
  cgm->emitOpenACCRoutineDecl(FD, entry, RD->getBeginLoc(), RD->clauses());
}
 
void CIRGenerator::CompleteTentativeDefinition(VarDecl *d) {
  if (diags.hasErrorOccurred())
    return;
 
  cgm->emitTentativeDefinition(d);
}
 
void CIRGenerator::HandleVTable(CXXRecordDecl *rd) {
  if (diags.hasErrorOccurred())
    return;
 
  cgm->emitVTable(rd);
}