[clang-ifs] Clang Interface Stubs, first version (second landing attempt).

This change reverts r363649; effectively re-landing r363626. At this point
clang::Index::CodegenNameGeneratorImpl has been refactored into
clang::AST::ASTNameGenerator. This makes it so that the previous circular link
dependency no longer exists, fixing the previous share lib
(-DBUILD_SHARED_LIBS=ON) build issue which was the reason for r363649.

Clang interface stubs (previously referred to as clang-ifsos) is a new frontend
action in clang that allows the generation of stub files that contain mangled
name info that can be used to produce a stub library. These stub libraries can
be useful for breaking up build dependencies and controlling access to a
library's internal symbols. Generation of these stubs can be invoked by:

clang -fvisibility=<visibility> -emit-interface-stubs \
                                -interface-stub-version=<interface format>

Notice that -fvisibility (along with use of visibility attributes) can be used
to control what symbols get generated. Currently the interface format is
experimental but there are a wide range of possibilities here.

Currently clang-ifs produces .ifs files that can be thought of as analogous to
object (.o) files, but just for the mangled symbol info. In a subsequent patch
I intend to add support for merging the .ifs files into one .ifs/.ifso file
that can be the input to something like llvm-elfabi to produce something like a
.so file or .dll (but without any of the code, just symbols).

Differential Revision: https://reviews.llvm.org/D60974


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@363948 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 378 insertions, 0 deletions

diff --git a/lib/Frontend/InterfaceStubFunctionsConsumer.cpp b/lib/Frontend/InterfaceStubFunctionsConsumer.cpp
new file mode 100644
index 0000000000..fbba9ae4d6
--- /dev/null
+++ b/lib/Frontend/InterfaceStubFunctionsConsumer.cpp
@@ -0,0 +1,378 @@
+//===--- InterfaceStubFunctionsConsumer.cpp -------------------------------===//
+//
+// 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 "clang/AST/Mangle.h"
+#include "clang/AST/RecursiveASTVisitor.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Frontend/FrontendActions.h"
+#include "clang/Sema/TemplateInstCallback.h"
+#include "llvm/BinaryFormat/ELF.h"
+
+using namespace clang;
+
+class InterfaceStubFunctionsConsumer : public ASTConsumer {
+  CompilerInstance &Instance;
+  StringRef InFile;
+  StringRef Format;
+  std::set<std::string> ParsedTemplates;
+
+  enum RootDeclOrigin { TopLevel = 0, FromTU = 1, IsLate = 2 };
+  struct MangledSymbol {
+    std::string ParentName;
+    uint8_t Type;
+    uint8_t Binding;
+    std::vector<std::string> Names;
+    MangledSymbol() = delete;
+
+    MangledSymbol(const std::string &ParentName, uint8_t Type, uint8_t Binding,
+                  std::vector<std::string> Names)
+        : ParentName(ParentName), Type(Type), Binding(Binding), Names(Names) {}
+  };
+  using MangledSymbols = std::map<const NamedDecl *, MangledSymbol>;
+
+  bool WriteNamedDecl(const NamedDecl *ND, MangledSymbols &Symbols, int RDO) {
+    // Here we filter out anything that's not set to DefaultVisibility.
+    // DefaultVisibility is set on a decl when -fvisibility is not specified on
+    // the command line (or specified as default) and the decl does not have
+    // __attribute__((visibility("hidden"))) set or when the command line
+    // argument is set to hidden but the decl explicitly has
+    // __attribute__((visibility ("default"))) set. We do this so that the user
+    // can have fine grain control of what they want to expose in the stub.
+    auto isVisible = [](const NamedDecl *ND) -> bool {
+      return ND->getVisibility() == DefaultVisibility;
+    };
+
+    auto ignoreDecl = [this, isVisible](const NamedDecl *ND) -> bool {
+      if (!isVisible(ND))
+        return true;
+
+      if (const VarDecl *VD = dyn_cast<VarDecl>(ND))
+        if ((VD->getStorageClass() == StorageClass::SC_Extern) ||
+            (VD->getStorageClass() == StorageClass::SC_Static &&
+             VD->getParentFunctionOrMethod() == nullptr))
+          return true;
+
+      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
+        if (FD->isInlined() && !isa<CXXMethodDecl>(FD) &&
+            !Instance.getLangOpts().GNUInline)
+          return true;
+        if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
+          if (const auto *RC = dyn_cast<CXXRecordDecl>(MD->getParent()))
+            if (isa<ClassTemplateDecl>(RC->getParent()) || !isVisible(RC))
+              return true;
+          if (MD->isDependentContext() || !MD->hasBody())
+            return true;
+        }
+        if (FD->getStorageClass() == StorageClass::SC_Static)
+          return true;
+      }
+      return false;
+    };
+
+    auto getParentFunctionDecl = [](const NamedDecl *ND) -> const NamedDecl * {
+      if (const VarDecl *VD = dyn_cast<VarDecl>(ND))
+        if (const auto *FD =
+                dyn_cast_or_null<FunctionDecl>(VD->getParentFunctionOrMethod()))
+          return FD;
+      return nullptr;
+    };
+
+    auto getMangledNames = [](const NamedDecl *ND) -> std::vector<std::string> {
+      if (!ND)
+        return {""};
+      ASTNameGenerator NameGen(ND->getASTContext());
+      std::vector<std::string> MangledNames = NameGen.getAllManglings(ND);
+      if (isa<CXXConstructorDecl>(ND) || isa<CXXDestructorDecl>(ND))
+        return MangledNames;
+#ifdef EXPENSIVE_CHECKS
+      assert(MangledNames.size() <= 1 && "Expected only one name mangling.");
+#endif
+      return {NameGen.getName(ND)};
+    };
+
+    if (!(RDO & FromTU))
+      return true;
+    if (Symbols.find(ND) != Symbols.end())
+      return true;
+    // - Currently have not figured out how to produce the names for FieldDecls.
+    // - Do not want to produce symbols for function paremeters.
+    if (isa<FieldDecl>(ND) || isa<ParmVarDecl>(ND))
+      return true;
+
+    const NamedDecl *ParentDecl = getParentFunctionDecl(ND);
+    if ((ParentDecl && ignoreDecl(ParentDecl)) || ignoreDecl(ND))
+      return true;
+
+    if (RDO & IsLate) {
+      Instance.getDiagnostics().Report(diag::err_asm_invalid_type_in_input)
+          << "Generating Interface Stubs is not supported with "
+             "delayed template parsing.";
+    } else {
+      if (const auto *FD = dyn_cast<FunctionDecl>(ND))
+        if (FD->isDependentContext())
+          return true;
+
+      const bool IsWeak = (ND->hasAttr<WeakAttr>() ||
+                           ND->hasAttr<WeakRefAttr>() || ND->isWeakImported());
+
+      Symbols.insert(std::make_pair(
+          ND,
+          MangledSymbol(getMangledNames(ParentDecl).front(),
+                        // Type:
+                        isa<VarDecl>(ND) ? llvm::ELF::STT_OBJECT
+                                         : llvm::ELF::STT_FUNC,
+                        // Binding:
+                        IsWeak ? llvm::ELF::STB_WEAK : llvm::ELF::STB_GLOBAL,
+                        getMangledNames(ND))));
+    }
+    return true;
+  }
+
+  void
+  HandleDecls(const llvm::iterator_range<DeclContext::decl_iterator> &Decls,
+              MangledSymbols &Symbols, int RDO) {
+    for (const auto *D : Decls)
+      HandleNamedDecl(dyn_cast<NamedDecl>(D), Symbols, RDO);
+  }
+
+  void HandleTemplateSpecializations(const FunctionTemplateDecl &FTD,
+                                     MangledSymbols &Symbols, int RDO) {
+    for (const auto *D : FTD.specializations())
+      HandleNamedDecl(dyn_cast<NamedDecl>(D), Symbols, RDO);
+  }
+
+  void HandleTemplateSpecializations(const ClassTemplateDecl &CTD,
+                                     MangledSymbols &Symbols, int RDO) {
+    for (const auto *D : CTD.specializations())
+      HandleNamedDecl(dyn_cast<NamedDecl>(D), Symbols, RDO);
+  }
+
+  bool HandleNamedDecl(const NamedDecl *ND, MangledSymbols &Symbols, int RDO) {
+    if (!ND)
+      return false;
+
+    switch (ND->getKind()) {
+    default:
+      break;
+    case Decl::Kind::Namespace:
+      HandleDecls(cast<NamespaceDecl>(ND)->decls(), Symbols, RDO);
+      return true;
+    case Decl::Kind::CXXRecord:
+      HandleDecls(cast<CXXRecordDecl>(ND)->decls(), Symbols, RDO);
+      return true;
+    case Decl::Kind::ClassTemplateSpecialization:
+      HandleDecls(cast<ClassTemplateSpecializationDecl>(ND)->decls(), Symbols,
+                  RDO);
+      return true;
+    case Decl::Kind::ClassTemplate:
+      HandleTemplateSpecializations(*cast<ClassTemplateDecl>(ND), Symbols, RDO);
+      return true;
+    case Decl::Kind::FunctionTemplate:
+      HandleTemplateSpecializations(*cast<FunctionTemplateDecl>(ND), Symbols,
+                                    RDO);
+      return true;
+    case Decl::Kind::TemplateTypeParm:
+      return true;
+    case Decl::Kind::Var:
+    case Decl::Kind::ParmVar:
+    case Decl::Kind::CXXMethod:
+    case Decl::Kind::CXXConstructor:
+    case Decl::Kind::CXXDestructor:
+    case Decl::Kind::Function:
+    case Decl::Kind::Field:
+      if (WriteNamedDecl(ND, Symbols, RDO))
+        return true;
+    }
+
+    // While interface stubs are in the development stage, it's probably best to
+    // catch anything that's not a VarDecl or Template/FunctionDecl.
+    Instance.getDiagnostics().Report(diag::err_asm_invalid_type_in_input)
+        << "Expected a function or function template decl.";
+    return false;
+  }
+
+public:
+  InterfaceStubFunctionsConsumer(CompilerInstance &Instance, StringRef InFile,
+                                 StringRef Format)
+      : Instance(Instance), InFile(InFile), Format(Format) {}
+
+  void HandleTranslationUnit(ASTContext &context) override {
+    struct Visitor : public RecursiveASTVisitor<Visitor> {
+      bool VisitNamedDecl(NamedDecl *ND) {
+        if (const auto *FD = dyn_cast<FunctionDecl>(ND))
+          if (FD->isLateTemplateParsed()) {
+            LateParsedDecls.insert(FD);
+            return true;
+          }
+
+        if (const auto *VD = dyn_cast<ValueDecl>(ND)) {
+          ValueDecls.insert(VD);
+          return true;
+        }
+
+        NamedDecls.insert(ND);
+        return true;
+      }
+
+      std::set<const NamedDecl *> LateParsedDecls;
+      std::set<NamedDecl *> NamedDecls;
+      std::set<const ValueDecl *> ValueDecls;
+    } v;
+
+    v.TraverseDecl(context.getTranslationUnitDecl());
+
+    MangledSymbols Symbols;
+    auto OS = Instance.createDefaultOutputFile(/*Binary=*/false, InFile, "ifs");
+    if (!OS)
+      return;
+
+    if (Instance.getLangOpts().DelayedTemplateParsing) {
+      clang::Sema &S = Instance.getSema();
+      for (const auto *FD : v.LateParsedDecls) {
+        clang::LateParsedTemplate &LPT =
+            *S.LateParsedTemplateMap.find(cast<FunctionDecl>(FD))->second;
+        S.LateTemplateParser(S.OpaqueParser, LPT);
+        HandleNamedDecl(FD, Symbols, (FromTU | IsLate));
+      }
+    }
+
+    for (const NamedDecl *ND : v.ValueDecls)
+      HandleNamedDecl(ND, Symbols, FromTU);
+    for (const NamedDecl *ND : v.NamedDecls)
+      HandleNamedDecl(ND, Symbols, FromTU);
+
+    auto writeIfoYaml = [this](const llvm::Triple &T,
+                               const MangledSymbols &Symbols,
+                               const ASTContext &context, StringRef Format,
+                               raw_ostream &OS) -> void {
+      OS << "--- !" << Format << "\n";
+      OS << "FileHeader:\n";
+      OS << "  Class:           ELFCLASS";
+      OS << (T.isArch64Bit() ? "64" : "32");
+      OS << "\n";
+      OS << "  Data:            ELFDATA2";
+      OS << (T.isLittleEndian() ? "LSB" : "MSB");
+      OS << "\n";
+      OS << "  Type:            ET_REL\n";
+      OS << "  Machine:         "
+         << llvm::StringSwitch<llvm::StringRef>(T.getArchName())
+                .Case("x86_64", "EM_X86_64")
+                .Case("i386", "EM_386")
+                .Case("i686", "EM_386")
+                .Case("aarch64", "EM_AARCH64")
+                .Case("amdgcn", "EM_AMDGPU")
+                .Case("r600", "EM_AMDGPU")
+                .Case("arm", "EM_ARM")
+                .Case("thumb", "EM_ARM")
+                .Case("avr", "EM_AVR")
+                .Case("mips", "EM_MIPS")
+                .Case("mipsel", "EM_MIPS")
+                .Case("mips64", "EM_MIPS")
+                .Case("mips64el", "EM_MIPS")
+                .Case("msp430", "EM_MSP430")
+                .Case("ppc", "EM_PPC")
+                .Case("ppc64", "EM_PPC64")
+                .Case("ppc64le", "EM_PPC64")
+                .Case("x86", T.isOSIAMCU() ? "EM_IAMCU" : "EM_386")
+                .Case("x86_64", "EM_X86_64")
+                .Default("EM_NONE")
+         << "\nSymbols:\n";
+      for (const auto &E : Symbols) {
+        const MangledSymbol &Symbol = E.second;
+        for (auto Name : Symbol.Names) {
+          OS << "  - Name:            "
+             << (Symbol.ParentName.empty() || Instance.getLangOpts().CPlusPlus
+                     ? ""
+                     : (Symbol.ParentName + "."))
+             << Name << "\n"
+             << "    Type:            STT_";
+          switch (Symbol.Type) {
+          default:
+          case llvm::ELF::STT_NOTYPE:
+            OS << "NOTYPE";
+            break;
+          case llvm::ELF::STT_OBJECT:
+            OS << "OBJECT";
+            break;
+          case llvm::ELF::STT_FUNC:
+            OS << "FUNC";
+            break;
+          }
+          OS << "\n    Binding:         STB_"
+             << ((Symbol.Binding == llvm::ELF::STB_WEAK) ? "WEAK" : "GLOBAL")
+             << "\n";
+        }
+      }
+      OS << "...\n";
+      OS.flush();
+    };
+
+    auto writeIfoElfAbiYaml =
+        [this](const llvm::Triple &T, const MangledSymbols &Symbols,
+               const ASTContext &context, StringRef Format,
+               raw_ostream &OS) -> void {
+      OS << "--- !" << Format << "\n";
+      OS << "TbeVersion: 1.0\n";
+      OS << "Arch: " << T.getArchName() << "\n";
+      OS << "Symbols:\n";
+      for (const auto &E : Symbols) {
+        const MangledSymbol &Symbol = E.second;
+        for (auto Name : Symbol.Names) {
+          OS << "  "
+             << (Symbol.ParentName.empty() || Instance.getLangOpts().CPlusPlus
+                     ? ""
+                     : (Symbol.ParentName + "."))
+             << Name << ": { Type: ";
+          switch (Symbol.Type) {
+          default:
+            llvm_unreachable(
+                "clang -emit-iterface-stubs: Unexpected symbol type.");
+          case llvm::ELF::STT_NOTYPE:
+            OS << "NoType";
+            break;
+          case llvm::ELF::STT_OBJECT: {
+            auto VD = cast<ValueDecl>(E.first)->getType();
+            OS << "Object, Size: "
+               << context.getTypeSizeInChars(VD).getQuantity();
+            break;
+          }
+          case llvm::ELF::STT_FUNC:
+            OS << "Func";
+            break;
+          }
+          if (Symbol.Binding == llvm::ELF::STB_WEAK)
+            OS << ", Weak: true";
+          OS << " }\n";
+        }
+      }
+      OS << "...\n";
+      OS.flush();
+    };
+
+    if (Format == "experimental-yaml-elf-v1")
+      writeIfoYaml(Instance.getTarget().getTriple(), Symbols, context, Format,
+                   *OS);
+    else
+      writeIfoElfAbiYaml(Instance.getTarget().getTriple(), Symbols, context,
+                         Format, *OS);
+  }
+};
+
+std::unique_ptr<ASTConsumer>
+GenerateInterfaceYAMLExpV1Action::CreateASTConsumer(CompilerInstance &CI,
+                                                    StringRef InFile) {
+  return llvm::make_unique<InterfaceStubFunctionsConsumer>(
+      CI, InFile, "experimental-yaml-elf-v1");
+}
+
+std::unique_ptr<ASTConsumer>
+GenerateInterfaceTBEExpV1Action::CreateASTConsumer(CompilerInstance &CI,
+                                                   StringRef InFile) {
+  return llvm::make_unique<InterfaceStubFunctionsConsumer>(
+      CI, InFile, "experimental-tapi-elf-v1");
+}