[lld] COFF: Implement /lldmap flag.

[pcc]

Summary

This flag can be used to produce a map file, which is essentially a list
of objects linked into the final output file together with the RVAs of
their symbols. Because our format differs from MSVC's we expose it as a
separate flag.

[ruiu]

LGTM with a few nits.

COFF/Driver.cpp

604 ↗

(On Diff #28581)

Add using at beginning of this file and use F_Text for consistency.

COFF/Options.td

93 ↗

(On Diff #28581)

Please remove this flag since it's dead.

COFF/SymbolTable.cpp

244 ↗

(On Diff #28581)

auto *R = ...

lld/trunk/COFF/Driver.cpp

 #include <algorithm>
 #include <memory>
 
 using namespace llvm;
 using llvm::COFF::IMAGE_SUBSYSTEM_UNKNOWN;
 using llvm::COFF::IMAGE_SUBSYSTEM_WINDOWS_CUI;
 using llvm::COFF::IMAGE_SUBSYSTEM_WINDOWS_GUI;
 using llvm::sys::Process;
+using llvm::sys::fs::OpenFlags::F_Text;
 using llvm::sys::fs::file_magic;
 using llvm::sys::fs::identify_magic;
 
 namespace lld {
 namespace coff {
 
 Configuration *Config;
 LinkerDriver *Driver;
if (createSideBySideManifest())
       return false;
 
   // Write the result.
   Writer Out(&Symtab);
   if (auto EC = Out.write(Config->OutputFile)) {
     llvm::errs() << EC.message() << "\n";
     return false;
   }
+
+  if (auto *Arg = Args.getLastArg(OPT_lldmap)) {
+    std::error_code EC;
+    llvm::raw_fd_ostream Out(Arg->getValue(), EC, F_Text);
+    if (EC) {
+      llvm::errs() << EC.message() << "\n";
+      return false;
+    }
+    Symtab.printMap(Out);
+  }
+
   return true;
 }
 
 } // namespace coff
 } // namespace lld

lld/trunk/COFF/Options.td

 defm safeseh : B<"safeseh", "Produce an image with Safe Exception Handler">;
 defm tsaware  : B<"tsaware", "Create non-Terminal Server aware executable">;
 
 def help : F<"help">;
 def help_q : Flag<["/?", "-?"], "">, Alias<help>;
 
 def DASH_DASH : Option<["--"], "", KIND_REMAINING_ARGS>;
 
-// Flag for debug
-def lldmoduledeffile : Joined<["/", "-"], "lldmoduledeffile:">;
+// Flags for debugging
+def lldmap : Joined<["/", "-"], "lldmap:">;
 
 //==============================================================================
 // The flags below do nothing. They are defined only for link.exe compatibility.
 //==============================================================================
 
 class QF<string name> : Joined<["/", "-", "-?"], name#":">;
 
 multiclass QB<string name> {

lld/trunk/COFF/SymbolTable.h

 //===- SymbolTable.h ------------------------------------------------------===//
 //
 //                             The LLVM Linker
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLD_COFF_SYMBOL_TABLE_H
 #define LLD_COFF_SYMBOL_TABLE_H
 
 #include "InputFiles.h"
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/raw_ostream.h"
 #include <unordered_map>
 
 namespace llvm {
 struct LTOCodeGenerator;
 }
 
 namespace lld {
 namespace coff {
public:
   // choose the right one depending on which `main` function is defined.
   // This function looks up the symbol table and resolve corresponding
   // entry point name.
   ErrorOr<StringRef> findDefaultEntry();
 
   // Dump contents of the symbol table to stderr.
   void dump();
 
+  // Print a layout map to OS.
+  void printMap(llvm::raw_ostream &OS);
+
   // Build a COFF object representing the combined contents of BitcodeFiles
   // and add it to the symbol table. Called after all files are added and
   // before the writer writes results to a file.
   std::error_code addCombinedLTOObject();
 
   // The writer needs to handle DLL import libraries specially in
   // order to create the import descriptor table.
   std::vector<ImportFile *> ImportFiles;

lld/trunk/COFF/SymbolTable.cpp

void SymbolTable::dump() {
   for (auto &P : Symtab) {
     Symbol *Ref = P.second;
     if (auto *Body = dyn_cast<Defined>(Ref->Body))
       llvm::dbgs() << Twine::utohexstr(Config->ImageBase + Body->getRVA())
                    << " " << Body->getName() << "\n";
   }
 }
 
+void SymbolTable::printMap(llvm::raw_ostream &OS) {
+  for (ObjectFile *File : ObjectFiles) {
+    OS << File->getShortName() << ":\n";
+    for (SymbolBody *Body : File->getSymbols())
+      if (auto *R = dyn_cast<DefinedRegular>(Body))
+        if (R->isLive())
+          OS << Twine::utohexstr(Config->ImageBase + R->getRVA())
+             << " " << R->getName() << "\n";
+  }
+}
+
 std::error_code SymbolTable::addCombinedLTOObject() {
   if (BitcodeFiles.empty())
     return std::error_code();
 
   // Create an object file and add it to the symbol table by replacing any
   // DefinedBitcode symbols with the definitions in the object file.
   LTOCodeGenerator CG;
   auto FileOrErr = createLTOObject(&CG);

lld/trunk/COFF/Symbols.h

public:
   }
 
   StringRef getName() override;
   uint64_t getRVA() override { return (*Data)->getRVA() + Sym.getValue(); }
   bool isExternal() override { return Sym.isExternal(); }
   int compare(SymbolBody *Other) override;
   std::string getDebugName() override;
   bool isCOMDAT() { return IsCOMDAT; }
+  bool isLive() const { return (*Data)->isLive(); }
   void markLive() { (*Data)->markLive(); }
   Chunk *getChunk() { return *Data; }
 
 private:
   StringRef Name;
   ObjectFile *File;
   COFFSymbolRef Sym;
   SectionChunk **Data;

lld/trunk/test/COFF/lldmap.test

+# RUN: yaml2obj < %p/Inputs/ret42.yaml > %t.obj
+# RUN: lld -flavor link2 /out:%t.exe /lldmap:%t.map %t.obj
+# RUN: FileCheck %s < %t.map
+
+# CHECK: .obj:
+# CHECK-NEXT: 140001000 .text$mn
+# CHECK-NEXT: 140001000 .data
+# CHECK-NEXT: 140001000 mainCRTStartup