clang/lib/CodeGen/ModuleBuilder.cpp

   1 //===--- ModuleBuilder.cpp - Emit LLVM Code from ASTs ---------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This builds an AST and converts it to LLVM Code.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "clang/CodeGen/ModuleBuilder.h"
  14 #include "CGDebugInfo.h"
  15 #include "CodeGenModule.h"
  16 #include "clang/AST/ASTContext.h"
  17 #include "clang/AST/DeclObjC.h"
  18 #include "clang/AST/Expr.h"
  19 #include "clang/Basic/CodeGenOptions.h"
  20 #include "clang/Basic/Diagnostic.h"
  21 #include "clang/Basic/TargetInfo.h"
  22 #include "llvm/ADT/StringRef.h"
  23 #include "llvm/IR/DataLayout.h"
  24 #include "llvm/IR/LLVMContext.h"
  25 #include "llvm/IR/Module.h"
  26 #include "llvm/Support/VirtualFileSystem.h"
  27 #include <memory>
  28
  29 using namespace clang;
  30 using namespace CodeGen;
  31
  32 namespace {
  33   class CodeGeneratorImpl : public CodeGenerator {
  34     DiagnosticsEngine &Diags;
  35     ASTContext *Ctx;
  36     IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS; // Only used for debug info.
  37     const HeaderSearchOptions &HeaderSearchOpts; // Only used for debug info.
  38     const PreprocessorOptions &PreprocessorOpts; // Only used for debug info.
  39     const CodeGenOptions &CodeGenOpts;
  40
  41     unsigned HandlingTopLevelDecls;
  42
  43     /// Use this when emitting decls to block re-entrant decl emission. It will
  44     /// emit all deferred decls on scope exit. Set EmitDeferred to false if decl
  45     /// emission must be deferred longer, like at the end of a tag definition.
  46     struct HandlingTopLevelDeclRAII {
  47       CodeGeneratorImpl &Self;
  48       bool EmitDeferred;
  49       HandlingTopLevelDeclRAII(CodeGeneratorImpl &Self,
  50                                bool EmitDeferred = true)
  51           : Self(Self), EmitDeferred(EmitDeferred) {
  52         ++Self.HandlingTopLevelDecls;
  53       }
  54       ~HandlingTopLevelDeclRAII() {
  55         unsigned Level = --Self.HandlingTopLevelDecls;
  56         if (Level == 0 && EmitDeferred)
  57           Self.EmitDeferredDecls();
  58       }
  59     };
  60
  61     CoverageSourceInfo *CoverageInfo;
  62
  63   protected:
  64     std::unique_ptr<llvm::Module> M;
  65     std::unique_ptr<CodeGen::CodeGenModule> Builder;
  66
  67   private:
  68     SmallVector<FunctionDecl *, 8> DeferredInlineMemberFuncDefs;
  69
  70     static llvm::StringRef ExpandModuleName(llvm::StringRef ModuleName,
  71                                             const CodeGenOptions &CGO) {
  72       if (ModuleName == "-" && !CGO.MainFileName.empty())
  73         return CGO.MainFileName;
  74       return ModuleName;
  75     }
  76
  77   public:
  78     CodeGeneratorImpl(DiagnosticsEngine &diags, llvm::StringRef ModuleName,
  79                       IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS,
  80                       const HeaderSearchOptions &HSO,
  81                       const PreprocessorOptions &PPO, const CodeGenOptions &CGO,
  82                       llvm::LLVMContext &C,
  83                       CoverageSourceInfo *CoverageInfo = nullptr)
  84         : Diags(diags), Ctx(nullptr), FS(std::move(FS)), HeaderSearchOpts(HSO),
  85           PreprocessorOpts(PPO), CodeGenOpts(CGO), HandlingTopLevelDecls(0),
  86           CoverageInfo(CoverageInfo),
  87           M(new llvm::Module(ExpandModuleName(ModuleName, CGO), C)) {
  88       C.setDiscardValueNames(CGO.DiscardValueNames);
  89     }
  90
  91     ~CodeGeneratorImpl() override {
  92       // There should normally not be any leftover inline method definitions.
  93       assert(DeferredInlineMemberFuncDefs.empty() ||
  94              Diags.hasErrorOccurred());
  95     }
  96
  97     CodeGenModule &CGM() {
  98       return *Builder;
  99     }
 100
 101     llvm::Module *GetModule() {
 102       return M.get();
 103     }
 104
 105     CGDebugInfo *getCGDebugInfo() {
 106       return Builder->getModuleDebugInfo();
 107     }
 108
 109     llvm::Module *ReleaseModule() {
 110       return M.release();
 111     }
 112
 113     const Decl *GetDeclForMangledName(StringRef MangledName) {
 114       GlobalDecl Result;
 115       if (!Builder->lookupRepresentativeDecl(MangledName, Result))
 116         return nullptr;
 117       const Decl *D = Result.getCanonicalDecl().getDecl();
 118       if (auto FD = dyn_cast<FunctionDecl>(D)) {
 119         if (FD->hasBody(FD))
 120           return FD;
 121       } else if (auto TD = dyn_cast<TagDecl>(D)) {
 122         if (auto Def = TD->getDefinition())
 123           return Def;
 124       }
 125       return D;
 126     }
 127
 128     llvm::StringRef GetMangledName(GlobalDecl GD) {
 129       return Builder->getMangledName(GD);
 130     }
 131
 132     llvm::Constant *GetAddrOfGlobal(GlobalDecl global, bool isForDefinition) {
 133       return Builder->GetAddrOfGlobal(global, ForDefinition_t(isForDefinition));
 134     }
 135
 136     llvm::Module *StartModule(llvm::StringRef ModuleName,
 137                               llvm::LLVMContext &C) {
 138       assert(!M && "Replacing existing Module?");
 139       M.reset(new llvm::Module(ExpandModuleName(ModuleName, CodeGenOpts), C));
 140
 141       std::unique_ptr<CodeGenModule> OldBuilder = std::move(Builder);
 142
 143       Initialize(*Ctx);
 144
 145       if (OldBuilder)
 146         OldBuilder->moveLazyEmissionStates(Builder.get());
 147
 148       return M.get();
 149     }
 150
 151     void Initialize(ASTContext &Context) override {
 152       Ctx = &Context;
 153
 154       M->setTargetTriple(Ctx->getTargetInfo().getTriple().getTriple());
 155       M->setDataLayout(Ctx->getTargetInfo().getDataLayoutString());
 156       const auto &SDKVersion = Ctx->getTargetInfo().getSDKVersion();
 157       if (!SDKVersion.empty())
 158         M->setSDKVersion(SDKVersion);
 159       if (const auto *TVT = Ctx->getTargetInfo().getDarwinTargetVariantTriple())
 160         M->setDarwinTargetVariantTriple(TVT->getTriple());
 161       if (auto TVSDKVersion =
 162               Ctx->getTargetInfo().getDarwinTargetVariantSDKVersion())
 163         M->setDarwinTargetVariantSDKVersion(*TVSDKVersion);
 164       Builder.reset(new CodeGen::CodeGenModule(Context, FS, HeaderSearchOpts,
 165                                                PreprocessorOpts, CodeGenOpts,
 166                                                *M, Diags, CoverageInfo));
 167
 168       for (auto &&Lib : CodeGenOpts.DependentLibraries)
 169         Builder->AddDependentLib(Lib);
 170       for (auto &&Opt : CodeGenOpts.LinkerOptions)
 171         Builder->AppendLinkerOptions(Opt);
 172     }
 173
 174     void HandleCXXStaticMemberVarInstantiation(VarDecl *VD) override {
 175       if (Diags.hasErrorOccurred())
 176         return;
 177
 178       Builder->HandleCXXStaticMemberVarInstantiation(VD);
 179     }
 180
 181     bool HandleTopLevelDecl(DeclGroupRef DG) override {
 182       // FIXME: Why not return false and abort parsing?
 183       if (Diags.hasErrorOccurred())
 184         return true;
 185
 186       HandlingTopLevelDeclRAII HandlingDecl(*this);
 187
 188       // Make sure to emit all elements of a Decl.
 189       for (DeclGroupRef::iterator I = DG.begin(), E = DG.end(); I != E; ++I)
 190         Builder->EmitTopLevelDecl(*I);
 191
 192       return true;
 193     }
 194
 195     void EmitDeferredDecls() {
 196       if (DeferredInlineMemberFuncDefs.empty())
 197         return;
 198
 199       // Emit any deferred inline method definitions. Note that more deferred
 200       // methods may be added during this loop, since ASTConsumer callbacks
 201       // can be invoked if AST inspection results in declarations being added.
 202       HandlingTopLevelDeclRAII HandlingDecl(*this);
 203       for (unsigned I = 0; I != DeferredInlineMemberFuncDefs.size(); ++I)
 204         Builder->EmitTopLevelDecl(DeferredInlineMemberFuncDefs[I]);
 205       DeferredInlineMemberFuncDefs.clear();
 206     }
 207
 208     void HandleInlineFunctionDefinition(FunctionDecl *D) override {
 209       if (Diags.hasErrorOccurred())
 210         return;
 211
 212       assert(D->doesThisDeclarationHaveABody());
 213
 214       // We may want to emit this definition. However, that decision might be
 215       // based on computing the linkage, and we have to defer that in case we
 216       // are inside of something that will change the method's final linkage,
 217       // e.g.
 218       //   typedef struct {
 219       //     void bar();
 220       //     void foo() { bar(); }
 221       //   } A;
 222       DeferredInlineMemberFuncDefs.push_back(D);
 223
 224       // Provide some coverage mapping even for methods that aren't emitted.
 225       // Don't do this for templated classes though, as they may not be
 226       // instantiable.
 227       if (!D->getLexicalDeclContext()->isDependentContext())
 228         Builder->AddDeferredUnusedCoverageMapping(D);
 229     }
 230
 231     /// HandleTagDeclDefinition - This callback is invoked each time a TagDecl
 232     /// to (e.g. struct, union, enum, class) is completed. This allows the
 233     /// client hack on the type, which can occur at any point in the file
 234     /// (because these can be defined in declspecs).
 235     void HandleTagDeclDefinition(TagDecl *D) override {
 236       if (Diags.hasErrorOccurred())
 237         return;
 238
 239       // Don't allow re-entrant calls to CodeGen triggered by PCH
 240       // deserialization to emit deferred decls.
 241       HandlingTopLevelDeclRAII HandlingDecl(*this, /*EmitDeferred=*/false);
 242
 243       Builder->UpdateCompletedType(D);
 244
 245       // For MSVC compatibility, treat declarations of static data members with
 246       // inline initializers as definitions.
 247       if (Ctx->getTargetInfo().getCXXABI().isMicrosoft()) {
 248         for (Decl *Member : D->decls()) {
 249           if (VarDecl *VD = dyn_cast<VarDecl>(Member)) {
 250             if (Ctx->isMSStaticDataMemberInlineDefinition(VD) &&
 251                 Ctx->DeclMustBeEmitted(VD)) {
 252               Builder->EmitGlobal(VD);
 253             }
 254           }
 255         }
 256       }
 257       // For OpenMP emit declare reduction functions, if required.
 258       if (Ctx->getLangOpts().OpenMP) {
 259         for (Decl *Member : D->decls()) {
 260           if (auto *DRD = dyn_cast<OMPDeclareReductionDecl>(Member)) {
 261             if (Ctx->DeclMustBeEmitted(DRD))
 262               Builder->EmitGlobal(DRD);
 263           } else if (auto *DMD = dyn_cast<OMPDeclareMapperDecl>(Member)) {
 264             if (Ctx->DeclMustBeEmitted(DMD))
 265               Builder->EmitGlobal(DMD);
 266           }
 267         }
 268       }
 269     }
 270
 271     void HandleTagDeclRequiredDefinition(const TagDecl *D) override {
 272       if (Diags.hasErrorOccurred())
 273         return;
 274
 275       // Don't allow re-entrant calls to CodeGen triggered by PCH
 276       // deserialization to emit deferred decls.
 277       HandlingTopLevelDeclRAII HandlingDecl(*this, /*EmitDeferred=*/false);
 278
 279       if (CodeGen::CGDebugInfo *DI = Builder->getModuleDebugInfo())
 280         if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
 281           DI->completeRequiredType(RD);
 282     }
 283
 284     void HandleTranslationUnit(ASTContext &Ctx) override {
 285       // Release the Builder when there is no error.
 286       if (!Diags.hasErrorOccurred() && Builder)
 287         Builder->Release();
 288
 289       // If there are errors before or when releasing the Builder, reset
 290       // the module to stop here before invoking the backend.
 291       if (Diags.hasErrorOccurred()) {
 292         if (Builder)
 293           Builder->clear();
 294         M.reset();
 295         return;
 296       }
 297     }
 298
 299     void AssignInheritanceModel(CXXRecordDecl *RD) override {
 300       if (Diags.hasErrorOccurred())
 301         return;
 302
 303       Builder->RefreshTypeCacheForClass(RD);
 304     }
 305
 306     void CompleteTentativeDefinition(VarDecl *D) override {
 307       if (Diags.hasErrorOccurred())
 308         return;
 309
 310       Builder->EmitTentativeDefinition(D);
 311     }
 312
 313     void CompleteExternalDeclaration(VarDecl *D) override {
 314       Builder->EmitExternalDeclaration(D);
 315     }
 316
 317     void HandleVTable(CXXRecordDecl *RD) override {
 318       if (Diags.hasErrorOccurred())
 319         return;
 320
 321       Builder->EmitVTable(RD);
 322     }
 323   };
 324 }
 325
 326 void CodeGenerator::anchor() { }
 327
 328 CodeGenModule &CodeGenerator::CGM() {
 329   return static_cast<CodeGeneratorImpl*>(this)->CGM();
 330 }
 331
 332 llvm::Module *CodeGenerator::GetModule() {
 333   return static_cast<CodeGeneratorImpl*>(this)->GetModule();
 334 }
 335
 336 llvm::Module *CodeGenerator::ReleaseModule() {
 337   return static_cast<CodeGeneratorImpl*>(this)->ReleaseModule();
 338 }
 339
 340 CGDebugInfo *CodeGenerator::getCGDebugInfo() {
 341   return static_cast<CodeGeneratorImpl*>(this)->getCGDebugInfo();
 342 }
 343
 344 const Decl *CodeGenerator::GetDeclForMangledName(llvm::StringRef name) {
 345   return static_cast<CodeGeneratorImpl*>(this)->GetDeclForMangledName(name);
 346 }
 347
 348 llvm::StringRef CodeGenerator::GetMangledName(GlobalDecl GD) {
 349   return static_cast<CodeGeneratorImpl *>(this)->GetMangledName(GD);
 350 }
 351
 352 llvm::Constant *CodeGenerator::GetAddrOfGlobal(GlobalDecl global,
 353                                                bool isForDefinition) {
 354   return static_cast<CodeGeneratorImpl*>(this)
 355            ->GetAddrOfGlobal(global, isForDefinition);
 356 }
 357
 358 llvm::Module *CodeGenerator::StartModule(llvm::StringRef ModuleName,
 359                                          llvm::LLVMContext &C) {
 360   return static_cast<CodeGeneratorImpl*>(this)->StartModule(ModuleName, C);
 361 }
 362
 363 CodeGenerator *
 364 clang::CreateLLVMCodeGen(DiagnosticsEngine &Diags, llvm::StringRef ModuleName,
 365                          IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS,
 366                          const HeaderSearchOptions &HeaderSearchOpts,
 367                          const PreprocessorOptions &PreprocessorOpts,
 368                          const CodeGenOptions &CGO, llvm::LLVMContext &C,
 369                          CoverageSourceInfo *CoverageInfo) {
 370   return new CodeGeneratorImpl(Diags, ModuleName, std::move(FS),
 371                                HeaderSearchOpts, PreprocessorOpts, CGO, C,
 372                                CoverageInfo);
 373 }