Forward #pragma comment(lib/linker) through as flags metadata

Summary:
Most of this change is wiring the pragma all the way through from the
lexer, parser, and sema to codegen.  I considered adding a Decl AST node
for this, but it seemed too heavyweight.

Mach-O already uses a metadata flag called "Linker Options" to do this
kind of auto-linking.  This change follows that pattern.

LLVM knows how to forward the "Linker Options" metadata into the COFF
.drectve section where these flags belong.  ELF support is not
implemented, but possible.

This is related to auto-linking, which is http://llvm.org/PR13016.

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D723

llvm-svn: 181426

Author: rnk

clang/include/clang/AST/ASTConsumer.h

@@ -14,6 +14,8 @@
 #ifndef LLVM_CLANG_AST_ASTCONSUMER_H
 #define LLVM_CLANG_AST_ASTCONSUMER_H
 
+#include "llvm/ADT/StringRef.h"
+
 namespace clang {
   class ASTContext;
   class CXXRecordDecl;
@@ -86,6 +88,15 @@ class ASTConsumer {
   /// The default implementation passes it to HandleTopLevelDecl.
   virtual void HandleImplicitImportDecl(ImportDecl *D);
 
+  /// \brief Handle a pragma that appends to Linker Options.  Currently this
+  /// only exists to support Microsoft's #pragma comment(linker, "/foo").
+  virtual void HandleLinkerOptionPragma(llvm::StringRef Opts) {}
+
+  /// \brief Handle a dependent library created by a pragma in the source.
+  /// Currently this only exists to support Microsoft's
+  /// #pragma comment(lib, "/foo").
+  virtual void HandleDependentLibrary(llvm::StringRef Lib) {}
+
   /// CompleteTentativeDefinition - Callback invoked at the end of a translation
   /// unit to notify the consumer that the given tentative definition should be
   /// completed.

clang/include/clang/Parse/Parser.h

@@ -418,6 +418,10 @@ class Parser : public CodeCompletionHandler {
   /// #pragma ms_struct...
   void HandlePragmaMSStruct();
 
+  /// \brief Handle the annotation token produced for
+  /// #pragma comment...
+  void HandlePragmaMSComment();
+
   /// \brief Handle the annotation token produced for
   /// #pragma align...
   void HandlePragmaAlign();

clang/include/clang/Sema/Sema.h

@@ -49,6 +49,7 @@
 #include "llvm/MC/MCParser/MCAsmParser.h"
 #include <deque>
 #include <string>
+#include <vector>
 
 namespace llvm {
   class APSInt;
@@ -6584,6 +6585,15 @@ class Sema {
     PMSST_ON    // #pragms ms_struct on
   };
 
+  enum PragmaMSCommentKind {
+    PCK_Unknown,
+    PCK_Linker,   // #pragma comment(linker, ...)
+    PCK_Lib,      // #pragma comment(lib, ...)
+    PCK_Compiler, // #pragma comment(compiler, ...)
+    PCK_ExeStr,   // #pragma comment(exestr, ...)
+    PCK_User      // #pragma comment(user, ...)
+  };
+
   /// ActOnPragmaPack - Called on well formed \#pragma pack(...).
   void ActOnPragmaPack(PragmaPackKind Kind,
                        IdentifierInfo *Name,
@@ -6595,6 +6605,9 @@ class Sema {
   /// ActOnPragmaMSStruct - Called on well formed \#pragma ms_struct [on|off].
   void ActOnPragmaMSStruct(PragmaMSStructKind Kind);
 
+  /// ActOnPragmaMSStruct - Called on well formed \#pragma comment(kind, "arg").
+  void ActOnPragmaMSComment(PragmaMSCommentKind Kind, StringRef Arg);
+
   /// ActOnPragmaUnused - Called on well-formed '\#pragma unused'.
   void ActOnPragmaUnused(const Token &Identifier,
                          Scope *curScope,

clang/lib/CodeGen/CodeGenAction.cpp

@@ -179,6 +179,14 @@ namespace clang {
       Gen->HandleVTable(RD, DefinitionRequired);
     }
 
+    virtual void HandleLinkerOptionPragma(llvm::StringRef Opts) {
+      Gen->HandleLinkerOptionPragma(Opts);
+    }
+
+    virtual void HandleDependentLibrary(llvm::StringRef Opts) {
+      Gen->HandleDependentLibrary(Opts);
+    }
+
     static void InlineAsmDiagHandler(const llvm::SMDiagnostic &SM,void *Context,
                                      unsigned LocCookie) {
       SourceLocation Loc = SourceLocation::getFromRawEncoding(LocCookie);

clang/lib/CodeGen/CodeGenModule.cpp

@@ -186,7 +186,8 @@ void CodeGenModule::Release() {
   EmitStaticExternCAliases();
   EmitLLVMUsed();
 
-  if (CodeGenOpts.Autolink && Context.getLangOpts().Modules) {
+  if (CodeGenOpts.Autolink &&
+      (Context.getLangOpts().Modules || !LinkerOptionsMetadata.empty())) {
     EmitModuleLinkOptions();
   }
 
@@ -762,31 +763,41 @@ void CodeGenModule::EmitLLVMUsed() {
   GV->setSection("llvm.metadata");
 }
 
+void CodeGenModule::AppendLinkerOptions(StringRef Opts) {
+  llvm::Value *MDOpts = llvm::MDString::get(getLLVMContext(), Opts);
+  LinkerOptionsMetadata.push_back(llvm::MDNode::get(getLLVMContext(), MDOpts));
+}
+
+void CodeGenModule::AddDependentLib(StringRef Lib) {
+  llvm::SmallString<24> Opt;
+  getTargetCodeGenInfo().getDependentLibraryOption(Lib, Opt);
+  llvm::Value *MDOpts = llvm::MDString::get(getLLVMContext(), Opt);
+  LinkerOptionsMetadata.push_back(llvm::MDNode::get(getLLVMContext(), MDOpts));
+}
+
 /// \brief Add link options implied by the given module, including modules
 /// it depends on, using a postorder walk.
-static void addLinkOptionsPostorder(llvm::LLVMContext &Context,
+static void addLinkOptionsPostorder(CodeGenModule &CGM,
                                     Module *Mod,
                                     SmallVectorImpl<llvm::Value *> &Metadata,
                                     llvm::SmallPtrSet<Module *, 16> &Visited) {
   // Import this module's parent.
   if (Mod->Parent && Visited.insert(Mod->Parent)) {
-    addLinkOptionsPostorder(Context, Mod->Parent, Metadata, Visited);
+    addLinkOptionsPostorder(CGM, Mod->Parent, Metadata, Visited);
   }
 
   // Import this module's dependencies.
   for (unsigned I = Mod->Imports.size(); I > 0; --I) {
     if (Visited.insert(Mod->Imports[I-1]))
-      addLinkOptionsPostorder(Context, Mod->Imports[I-1], Metadata, Visited);
+      addLinkOptionsPostorder(CGM, Mod->Imports[I-1], Metadata, Visited);
   }
 
   // Add linker options to link against the libraries/frameworks
   // described by this module.
+  llvm::LLVMContext &Context = CGM.getLLVMContext();
   for (unsigned I = Mod->LinkLibraries.size(); I > 0; --I) {
-    // FIXME: -lfoo is Unix-centric and -framework Foo is Darwin-centric.
-    // We need to know more about the linker to know how to encode these
-    // options propertly.
-
-    // Link against a framework.
+    // Link against a framework.  Frameworks are currently Darwin only, so we
+    // don't to ask TargetCodeGenInfo for the spelling of the linker option.
     if (Mod->LinkLibraries[I-1].IsFramework) {
       llvm::Value *Args[2] = {
         llvm::MDString::get(Context, "-framework"),
@@ -798,9 +809,10 @@ static void addLinkOptionsPostorder(llvm::LLVMContext &Context,
     }
 
     // Link against a library.
-    llvm::Value *OptString
-    = llvm::MDString::get(Context,
-                          "-l" + Mod->LinkLibraries[I-1].Library);
+    llvm::SmallString<24> Opt;
+    CGM.getTargetCodeGenInfo().getDependentLibraryOption(
+      Mod->LinkLibraries[I-1].Library, Opt);
+    llvm::Value *OptString = llvm::MDString::get(Context, Opt);
     Metadata.push_back(llvm::MDNode::get(Context, OptString));
   }
 }
@@ -852,20 +864,23 @@ void CodeGenModule::EmitModuleLinkOptions() {
   }
 
   // Add link options for all of the imported modules in reverse topological
-  // order.
+  // order.  We don't do anything to try to order import link flags with respect
+  // to linker options inserted by things like #pragma comment().
   SmallVector<llvm::Value *, 16> MetadataArgs;
   Visited.clear();
   for (llvm::SetVector<clang::Module *>::iterator M = LinkModules.begin(),
                                                MEnd = LinkModules.end();
        M != MEnd; ++M) {
     if (Visited.insert(*M))
-      addLinkOptionsPostorder(getLLVMContext(), *M, MetadataArgs, Visited);
+      addLinkOptionsPostorder(*this, *M, MetadataArgs, Visited);
   }
   std::reverse(MetadataArgs.begin(), MetadataArgs.end());
+  LinkerOptionsMetadata.append(MetadataArgs.begin(), MetadataArgs.end());
 
   // Add the linker options metadata flag.
   getModule().addModuleFlag(llvm::Module::AppendUnique, "Linker Options",
-                            llvm::MDNode::get(getLLVMContext(), MetadataArgs));
+                            llvm::MDNode::get(getLLVMContext(),
+                                              LinkerOptionsMetadata));
 }
 
 void CodeGenModule::EmitDeferred() {

clang/lib/CodeGen/CodeGenModule.h

@@ -355,6 +355,9 @@ class CodeGenModule : public CodeGenTypeCache {
   /// \brief The complete set of modules that has been imported.
   llvm::SetVector<clang::Module *> ImportedModules;
 
+  /// \brief A vector of metadata strings.
+  SmallVector<llvm::Value *, 16> LinkerOptionsMetadata;
+
   /// @name Cache for Objective-C runtime types
   /// @{
 
@@ -906,6 +909,12 @@ class CodeGenModule : public CodeGenTypeCache {
 
   void EmitVTable(CXXRecordDecl *Class, bool DefinitionRequired);
 
+  /// \brief Appends Opts to the "Linker Options" metadata value.
+  void AppendLinkerOptions(StringRef Opts);
+
+  /// \brief Appends a dependent lib to the "Linker Options" metadata value.
+  void AddDependentLib(StringRef Lib);
+
   llvm::GlobalVariable::LinkageTypes
   getFunctionLinkage(const FunctionDecl *FD);
 

clang/lib/CodeGen/ModuleBuilder.cpp

@@ -20,6 +20,7 @@
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Frontend/CodeGenOptions.h"
 #include "llvm/ADT/OwningPtr.h"
+#include "llvm/ADT/StringRef.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
@@ -115,6 +116,14 @@ namespace {
 
       Builder->EmitVTable(RD, DefinitionRequired);
     }
+
+    virtual void HandleLinkerOptionPragma(llvm::StringRef Opts) {
+      Builder->AppendLinkerOptions(Opts);
+    }
+
+    virtual void HandleDependentLibrary(llvm::StringRef Lib) {
+      Builder->AddDependentLib(Lib);
+    }
   };
 }
 

clang/lib/CodeGen/TargetInfo.cpp

@@ -143,6 +143,16 @@ bool TargetCodeGenInfo::isNoProtoCallVariadic(const CallArgList &args,
   return false;
 }
 
+void
+TargetCodeGenInfo::getDependentLibraryOption(llvm::StringRef Lib,
+                                             llvm::SmallString<24> &Opt) const {
+  // This assumes the user is passing a library name like "rt" instead of a
+  // filename like "librt.a/so", and that they don't care whether it's static or
+  // dynamic.
+  Opt = "-l";
+  Opt += Lib;
+}
+
 static bool isEmptyRecord(ASTContext &Context, QualType T, bool AllowArrays);
 
 /// isEmptyField - Return true iff a the field is "empty", that is it
@@ -1256,6 +1266,18 @@ class X86_64TargetCodeGenInfo : public TargetCodeGenInfo {
 
 };
 
+class WinX86_32TargetCodeGenInfo : public X86_32TargetCodeGenInfo {
+public:
+  WinX86_32TargetCodeGenInfo(CodeGen::CodeGenTypes &CGT, unsigned RegParms)
+    : X86_32TargetCodeGenInfo(CGT, false, true, true, RegParms) {}
+
+  void getDependentLibraryOption(llvm::StringRef Lib,
+                                 llvm::SmallString<24> &Opt) const {
+    Opt = "/DEFAULTLIB:";
+    Opt += Lib;
+  }
+};
+
 class WinX86_64TargetCodeGenInfo : public TargetCodeGenInfo {
 public:
   WinX86_64TargetCodeGenInfo(CodeGen::CodeGenTypes &CGT)
@@ -1274,6 +1296,12 @@ class WinX86_64TargetCodeGenInfo : public TargetCodeGenInfo {
     AssignToArrayRange(CGF.Builder, Address, Eight8, 0, 16);
     return false;
   }
+
+  void getDependentLibraryOption(llvm::StringRef Lib,
+                                 llvm::SmallString<24> &Opt) const {
+    Opt = "/DEFAULTLIB:";
+    Opt += Lib;
+  }
 };
 
 }
@@ -5173,8 +5201,8 @@ const TargetCodeGenInfo &CodeGenModule::getTargetCodeGenInfo() {
 
     case llvm::Triple::Win32:
       return *(TheTargetCodeGenInfo =
-               new X86_32TargetCodeGenInfo(Types, false, true, true,
-                                           CodeGenOpts.NumRegisterParameters));
+               new WinX86_32TargetCodeGenInfo(Types,
+                                              CodeGenOpts.NumRegisterParameters));
 
     default:
       return *(TheTargetCodeGenInfo =

clang/lib/CodeGen/TargetInfo.h

@@ -18,6 +18,7 @@
 #include "clang/AST/Type.h"
 #include "clang/Basic/LLVM.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/SmallString.h"
 
 namespace llvm {
   class GlobalValue;
@@ -167,6 +168,11 @@ namespace clang {
     /// that unprototyped calls to varargs functions still succeed.
     virtual bool isNoProtoCallVariadic(const CodeGen::CallArgList &args,
                                        const FunctionNoProtoType *fnType) const;
+
+    /// Gets the linker options necessary to link a dependent library on this
+    /// platform.
+    virtual void getDependentLibraryOption(llvm::StringRef Lib,
+                                           llvm::SmallString<24> &Opt) const;
   };
 }
 

clang/lib/Parse/ParsePragma.cpp

@@ -821,10 +821,16 @@ void PragmaCommentHandler::HandlePragma(Preprocessor &PP,
   }
 
   // Verify that this is one of the 5 whitelisted options.
-  // FIXME: warn that 'exestr' is deprecated.
-  const IdentifierInfo *II = Tok.getIdentifierInfo();
-  if (!II->isStr("compiler") && !II->isStr("exestr") && !II->isStr("lib") &&
-      !II->isStr("linker") && !II->isStr("user")) {
+  IdentifierInfo *II = Tok.getIdentifierInfo();
+  Sema::PragmaMSCommentKind Kind =
+    llvm::StringSwitch<Sema::PragmaMSCommentKind>(II->getName())
+    .Case("linker",   Sema::PCK_Linker)
+    .Case("lib",      Sema::PCK_Lib)
+    .Case("compiler", Sema::PCK_Compiler)
+    .Case("exestr",   Sema::PCK_ExeStr)
+    .Case("user",     Sema::PCK_User)
+    .Default(Sema::PCK_Unknown);
+  if (Kind == Sema::PCK_Unknown) {
     PP.Diag(Tok.getLocation(), diag::err_pragma_comment_unknown_kind);
     return;
   }
@@ -837,11 +843,12 @@ void PragmaCommentHandler::HandlePragma(Preprocessor &PP,
                                                  /*MacroExpansion=*/true))
     return;
 
+  // FIXME: warn that 'exestr' is deprecated.
   // FIXME: If the kind is "compiler" warn if the string is present (it is
   // ignored).
-  // FIXME: 'lib' requires a comment string.
-  // FIXME: 'linker' requires a comment string, and has a specific list of
-  // things that are allowable.
+  // The MSDN docs say that "lib" and "linker" require a string and have a short
+  // whitelist of linker options they support, but in practice MSVC doesn't
+  // issue a diagnostic.  Therefore neither does clang.
 
   if (Tok.isNot(tok::r_paren)) {
     PP.Diag(Tok.getLocation(), diag::err_pragma_comment_malformed);
@@ -857,4 +864,6 @@ void PragmaCommentHandler::HandlePragma(Preprocessor &PP,
   // If the pragma is lexically sound, notify any interested PPCallbacks.
   if (PP.getPPCallbacks())
     PP.getPPCallbacks()->PragmaComment(CommentLoc, II, ArgumentString);
+
+  Actions.ActOnPragmaMSComment(Kind, ArgumentString);
 }

clang/lib/Parse/ParsePragma.h

@@ -116,9 +116,12 @@ class PragmaOpenMPHandler : public PragmaHandler {
 /// PragmaCommentHandler - "\#pragma comment ...".
 class PragmaCommentHandler : public PragmaHandler {
 public:
-  PragmaCommentHandler() : PragmaHandler("comment") {}
+  PragmaCommentHandler(Sema &Actions)
+    : PragmaHandler("comment"), Actions(Actions) {}
   virtual void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
                             Token &FirstToken);
+private:
+  Sema &Actions;
 };
 
 }  // end namespace clang

clang/lib/Parse/Parser.cpp

@@ -103,7 +103,7 @@ Parser::Parser(Preprocessor &pp, Sema &actions, bool skipFunctionBodies)
   PP.AddPragmaHandler(OpenMPHandler.get());
 
   if (getLangOpts().MicrosoftExt) {
-    MSCommentHandler.reset(new PragmaCommentHandler());
+    MSCommentHandler.reset(new PragmaCommentHandler(actions));
     PP.AddPragmaHandler(MSCommentHandler.get());
   }