LLD: Introduce a GNU LD style driver for COFF

When building COFF programs many targets such as mingw prefer
to have a gnu ld frontend. Rather then having a fully fledged
standalone driver we wrap a shim around the LINK driver.

Extra tests were provided by mstorsjo

Reviewers: mstorsjo, ruiu

Differential Revision: https://reviews.llvm.org/D33880

llvm-svn: 312926

lld/CMakeLists.txt

@@ -221,4 +221,5 @@ endif()
 add_subdirectory(docs)
 add_subdirectory(COFF)
 add_subdirectory(ELF)
+add_subdirectory(MinGW)
 

lld/ELF/Driver.cpp

@@ -113,12 +113,8 @@ static std::tuple<ELFKind, uint16_t, uint8_t> parseEmulation(StringRef Emul) {
           .Case("elf_iamcu", {ELF32LEKind, EM_IAMCU})
           .Default({ELFNoneKind, EM_NONE});
 
-  if (Ret.first == ELFNoneKind) {
-    if (S == "i386pe" || S == "i386pep" || S == "thumb2pe")
-      error("Windows targets are not supported on the ELF frontend: " + Emul);
-    else
-      error("unknown emulation: " + Emul);
-  }
+  if (Ret.first == ELFNoneKind)
+    error("unknown emulation: " + Emul);
   return std::make_tuple(Ret.first, Ret.second, OSABI);
 }
 

lld/MinGW/CMakeLists.txt

@@ -0,0 +1,20 @@
+set(LLVM_TARGET_DEFINITIONS Options.td)
+tablegen(LLVM Options.inc -gen-opt-parser-defs)
+add_public_tablegen_target(ShimOptionsTableGen)
+
+if(NOT LLD_BUILT_STANDALONE)
+  set(tablegen_deps intrinsics_gen)
+endif()
+
+add_lld_library(lldMinGW
+  Driver.cpp
+
+  LINK_LIBS
+  lldConfig
+  lldCore
+  ${LLVM_PTHREAD_LIB}
+
+  DEPENDS
+  ShimOptionsTableGen
+  ${tablegen_deps}
+)

lld/MinGW/Driver.cpp

@@ -0,0 +1,204 @@
+//===- MinGW/Driver.cpp ---------------------------------------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// GNU ld style linker driver for COFF currently supporting mingw-w64.
+///
+//===----------------------------------------------------------------------===//
+
+#include "lld/Driver/Driver.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/Option/Arg.h"
+#include "llvm/Option/ArgList.h"
+#include "llvm/Option/Option.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
+
+#if !defined(_MSC_VER) && !defined(__MINGW32__)
+#include <unistd.h>
+#endif
+
+using namespace lld;
+using namespace llvm;
+
+namespace lld {
+namespace mingw {
+namespace {
+
+// Create OptTable
+enum {
+  OPT_INVALID = 0,
+#define OPTION(_1, _2, ID, _4, _5, _6, _7, _8, _9, _10, _11, _12) OPT_##ID,
+#include "Options.inc"
+#undef OPTION
+};
+
+// Create prefix string literals used in Options.td
+#define PREFIX(NAME, VALUE) const char *const NAME[] = VALUE;
+#include "Options.inc"
+#undef PREFIX
+
+// Create table mapping all options defined in Options.td
+static const opt::OptTable::Info InfoTable[] = {
+#define OPTION(X1, X2, ID, KIND, GROUP, ALIAS, X7, X8, X9, X10, X11, X12)      \
+  {X1, X2, X10,         X11,         OPT_##ID, opt::Option::KIND##Class,       \
+   X9, X8, OPT_##GROUP, OPT_##ALIAS, X7,       X12},
+#include "Options.inc"
+#undef OPTION
+};
+
+class COFFLdOptTable : public opt::OptTable {
+public:
+  COFFLdOptTable() : OptTable(InfoTable, false) {}
+  opt::InputArgList parse(ArrayRef<const char *> Argv);
+};
+
+} // namespace
+
+static std::vector<std::string> LinkArgs;
+static std::vector<StringRef> SearchPaths;
+
+static void error(const Twine &Msg) {
+  errs() << Msg << "\n";
+  llvm_shutdown();
+  exit(1);
+}
+
+// Find a file by concatenating given paths.
+static Optional<std::string> findFile(StringRef Path1, const Twine &Path2) {
+  SmallString<128> S;
+  sys::path::append(S, Path1, Path2);
+  if (sys::fs::exists(S))
+    return S.str().str();
+  return None;
+}
+
+static Optional<std::string> findFromSearchPaths(StringRef Path) {
+  for (StringRef Dir : SearchPaths)
+    if (Optional<std::string> S = findFile(Dir, Path))
+      return S;
+  return None;
+}
+
+// This is for -lfoo. We'll look for libfoo.dll.a or libfoo.a from search paths.
+static Optional<std::string> searchLibrary(StringRef Name, bool StaticOnly) {
+  if (Name.startswith(":"))
+    return findFromSearchPaths(Name.substr(1));
+  for (StringRef Dir : SearchPaths) {
+    if (!StaticOnly)
+      if (Optional<std::string> S = findFile(Dir, "lib" + Name + ".dll.a"))
+        return S;
+    if (Optional<std::string> S = findFile(Dir, "lib" + Name + ".a"))
+      return S;
+  }
+  return None;
+}
+
+// Add a given library by searching it from input search paths.
+static void addLibrary(StringRef Name, bool StaticOnly) {
+  if (Optional<std::string> Path = searchLibrary(Name, StaticOnly))
+    LinkArgs.push_back(*Path);
+  else
+    error("unable to find library -l" + Name);
+}
+
+static void createFiles(opt::InputArgList &Args) {
+  for (auto *Arg : Args) {
+    switch (Arg->getOption().getUnaliasedOption().getID()) {
+    case OPT_l:
+      addLibrary(Arg->getValue(), Args.hasArg(OPT_Bstatic));
+      break;
+    case OPT_INPUT:
+      LinkArgs.push_back(Arg->getValue());
+      break;
+    }
+  }
+}
+
+static void forward(opt::InputArgList &Args, unsigned Key,
+                    const std::string &OutArg, std::string Default = "") {
+  StringRef S = Args.getLastArgValue(Key);
+  if (!S.empty())
+    LinkArgs.push_back(std::string("-").append(OutArg).append(":").append(S));
+  else if (!Default.empty())
+    LinkArgs.push_back(
+        std::string("-").append(OutArg).append(":").append(Default));
+}
+
+static void forwardValue(opt::InputArgList &Args, unsigned Key,
+                         const std::string &CmpArg, const std::string &OutArg) {
+  StringRef S = Args.getLastArgValue(Key);
+  if (S == CmpArg)
+    LinkArgs.push_back(std::string("-").append(OutArg));
+}
+
+static bool convertValue(opt::InputArgList &Args, unsigned Key,
+                         StringRef OutArg) {
+  if (Args.hasArg(Key)) {
+    LinkArgs.push_back(std::string("-").append(OutArg));
+    return true;
+  }
+  return false;
+}
+
+opt::InputArgList COFFLdOptTable::parse(ArrayRef<const char *> Argv) {
+  unsigned MissingIndex;
+  unsigned MissingCount;
+  SmallVector<const char *, 256> Vec(Argv.data(), Argv.data() + Argv.size());
+  opt::InputArgList Args = this->ParseArgs(Vec, MissingIndex, MissingCount);
+  if (MissingCount)
+    error(Twine(Args.getArgString(MissingIndex)) + ": missing argument");
+  if (!Args.hasArgNoClaim(OPT_INPUT) && !Args.hasArgNoClaim(OPT_l))
+    error("no input files");
+  for (auto *Arg : Args.filtered(OPT_UNKNOWN))
+    error("unknown argument: " + Arg->getSpelling());
+  return Args;
+}
+
+bool link(ArrayRef<const char *> ArgsArr, raw_ostream &Diag) {
+  COFFLdOptTable Parser;
+  opt::InputArgList Args = Parser.parse(ArgsArr.slice(1));
+  LinkArgs.push_back(ArgsArr[0]);
+
+  forwardValue(Args, OPT_m, "i386pe", "machine:x86");
+  forwardValue(Args, OPT_m, "i386pep", "machine:x64");
+  forwardValue(Args, OPT_m, "thumb2pe", "machine:arm");
+  forwardValue(Args, OPT_m, "arm64pe", "machine:arm64");
+
+  forward(Args, OPT_o, "out",
+          convertValue(Args, OPT_shared, "dll") ? "a.dll" : "a.exe");
+  forward(Args, OPT_entry, "entry");
+  forward(Args, OPT_subs, "subsystem");
+  forward(Args, OPT_outlib, "implib");
+  forward(Args, OPT_stack, "stack");
+
+  for (auto *Arg : Args.filtered(OPT_L))
+    SearchPaths.push_back(Arg->getValue());
+
+  createFiles(Args);
+
+  // handle __image_base__
+  if (Args.getLastArgValue(OPT_m) == "i386pe")
+    LinkArgs.push_back("/alternatename:__image_base__=___ImageBase");
+  else
+    LinkArgs.push_back("/alternatename:__image_base__=__ImageBase");
+
+  // repack vector of strings to vector of const char pointers for coff::link
+  std::vector<const char *> Vec;
+  for (const std::string &S : LinkArgs)
+    Vec.push_back(S.c_str());
+  return coff::link(Vec);
+}
+
+} // namespace mingw
+} // namespace lld

lld/MinGW/Options.td

@@ -0,0 +1,34 @@
+include "llvm/Option/OptParser.td"
+
+class F<string name>: Flag<["--", "-"], name>;
+class J<string name>: Joined<["--", "-"], name>;
+class S<string name>: Separate<["--", "-"], name>;
+
+def L: JoinedOrSeparate<["-"], "L">, MetaVarName<"<dir>">,
+  HelpText<"Add a directory to the library search path">;
+def entry: S<"entry">, MetaVarName<"<entry>">,
+  HelpText<"Name of entry point symbol">;
+def m: JoinedOrSeparate<["-"], "m">, HelpText<"Set target emulation">;
+def o: JoinedOrSeparate<["-"], "o">, MetaVarName<"<path>">,
+  HelpText<"Path to file to write output">;
+def l: JoinedOrSeparate<["-"], "l">, MetaVarName<"<libName>">,
+  HelpText<"Root name of library to use">;
+def shared: F<"shared">, HelpText<"Build a shared object">;
+def subs: Separate<["--"], "subsystem">, HelpText<"Specify subsystem">;
+def stack: Separate<["--"], "stack">;
+def outlib: Separate<["--"], "out-implib">, HelpText<"Import library name">;
+
+// Currently stubs to avoid errors
+def Bdynamic: F<"Bdynamic">, HelpText<"Link against shared libraries">;
+def Bstatic: F<"Bstatic">, HelpText<"Do not link against shared libraries">;
+def major_image_version: Separate<["--"], "major-image-version">;
+def minor_image_version: Separate<["--"], "minor-image-version">;
+def enable_auto_image_base: Flag<["--"], "enable-auto-image-base">;
+def full_shutdown: Flag<["--"], "full-shutdown">;
+def O: Joined<["-"], "O">, HelpText<"Optimize output file size">;
+def v: Flag<["-"], "v">, HelpText<"Display the version number">;
+def verbose: F<"verbose">, HelpText<"Verbose mode">;
+def version: F<"version">, HelpText<"Display the version number and exit">;
+
+// Alias
+def alias_entry_e: JoinedOrSeparate<["-"], "e">, Alias<entry>;

lld/include/lld/Driver/Driver.h

@@ -19,6 +19,11 @@ bool link(llvm::ArrayRef<const char *> Args,
           llvm::raw_ostream &Diag = llvm::errs());
 }
 
+namespace mingw {
+bool link(llvm::ArrayRef<const char *> Args,
+          llvm::raw_ostream &Diag = llvm::errs());
+}
+
 namespace elf {
 bool link(llvm::ArrayRef<const char *> Args, bool CanExitEarly,
           llvm::raw_ostream &Diag = llvm::errs());

lld/test/MinGW/Inputs/imagebase-aarch64.yaml

@@ -0,0 +1,47 @@
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_ARM64
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     31C0C3666666662E0F1F84000000000031C0C3666666662E0F1F840000000000488D0500000000C3
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          40
+      NumberOfRelocations: 1
+      NumberOfLinenumbers: 0
+      CheckSum:        3930888477
+      Number:          1
+  - Name:            mainCRTStartup
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            main
+    Value:           16
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            func
+    Value:           32
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            __ImageBase
+    Value:           0
+    SectionNumber:   0
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...

lld/test/MinGW/Inputs/imagebase-arm.yaml

@@ -0,0 +1,47 @@
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_ARMNT
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     31C0C3666666662E0F1F84000000000031C0C3666666662E0F1F840000000000B800000000C3
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          38
+      NumberOfRelocations: 1
+      NumberOfLinenumbers: 0
+      CheckSum:        3189961473
+      Number:          1
+  - Name:            mainCRTStartup
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            main
+    Value:           16
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            func
+    Value:           32
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            __ImageBase
+    Value:           0
+    SectionNumber:   0
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...