[llvm-lipo] Implement -thin

[anushabasana]

Summary

Creates thin output file of specified arch_type from the fat input file.

Test Plan: check-llvm

[compnerd]

llvm/test/tools/llvm-lipo/thin-executable-universal-binary.test

2

Might be nice to have a comment about this explaining that the executable testing is not possible on Windows since all files are considered executable.

[mtrent]

I'll have a look Monday / early next week. Meanwhile, here are some quick thoughts.

llvm/tools/llvm-lipo/llvm-lipo.cpp

165

nit. s/to be specified//

178

not really sure what the right protocol for this is in LLVM-land. Should you file a bug in some LLVM-specific bug tracker? Or maybe should you print a warning/error saying a format is not (yet) supported?

I thought Archive files were SymbolicFiles and so they "should" be supported, but maybe you're using the wrong level of API? (I could be wrong ... just asking.)

276

Nit / optional. Since llmv-lipo is meant to be a drop-in replacement for lipo, this should ideally produce "input file (hello) must be a fat file when the -thin option is specified"

278

Since llmv-lipo is meant to be a drop-in replacement for lipo, this must be EXIT_FAILURE

286

Nit / optional. Since llmv-lipo is meant to be a drop-in replacement for lipo, this should ideally produce: "fat input file (<FILE NAME>) does not contain the specified architecture (<ARCH NAME>) to thin it to"

[alexander-shaposhnikov]

llvm/tools/llvm-lipo/llvm-lipo.cpp

278

+1

[anushabasana]

Added comments, fixed error messages, and print error for archive files.

[anushabasana]

Regarding the error messages, should should they replicate cctools lipo exactly?
Currently have small differences like "no output file specified" vs "thin expects a single output file".
If so, I can create a separate diff to change all the error messages.

llvm/tools/llvm-lipo/llvm-lipo.cpp

178

Added an error clarifying that archive files are not yet supported, but we will file a bug to implement this.
We are focusing on object files in this primary implementation.

[alexander-shaposhnikov]

i think that we should not "replicate cctools lipo error messages exactly", ours could be better / more convenient or informative where it makes sense.
But in this particular case (see the comments above) I agree, including the names into the error message would be good!
Regarding exit codes - yes, it's important (for many reasons) to make sure that our exit codes are correct.

[anushabasana]

llvm/tools/llvm-lipo/llvm-lipo.cpp

178

Bug 42310 - - llvm-lipo does not support archive files
https://bugs.llvm.org/show_bug.cgi?id=42310

[mtrent]

Would be nice if "llvm-lipo -thin" printed a reasonable error message before dumping usage. Apple lipo will print "missing argument to -thin option"

Another difference is llvm-lipo will not validate the arch until all arguments are received, whereas Apple lipo will validate archs immediately. ("lipo -arch asdf")

Would be nice if "llvm-lipo" printed a list of valid archs when the arch is invalid. Currently it prints "llvm-lipo: error: Invalid architecture: asdf" and it exits. Apple lipo prints "unknown architecture specification flag: asdf in specifying thin operation: -thin asdf. known architecture flags are: ..."

PLEASE FIX: llvm-lipo does not support using "-o" in place of "-output"

Note: "llvm-lipo" does not work properly with certain Mach-O executables, such as those built with the -hideARM64 flag.

[mtrent]

In D63341#1547398, @alexshap wrote:

i think that we should not "replicate cctools lipo error messages exactly", ours could be better / more convenient or informative where it makes sense.
But in this particular case (see the comments above) I agree, including the names into the error message would be good!
Regarding exit codes - yes, it's important (for many reasons) to make sure that our exit codes are correct.

I agree with all these points.

[alexander-shaposhnikov]

llvm/tools/llvm-lipo/llvm-lipo.cpp

300

khm, this works only because the method "commit" has not failed in your tests,
"commit" should not be called twice here. Basically, the correct "pattern" is the following:

if (Error E = OutFileOrError.get()->commit())
    reportError(OutputFileName, std::move(E));

[anushabasana]

Supports -o for output flag. Fixed order of error checking.

[anushabasana]

In D63341#1549652, @mtrent wrote:

Would be nice if "llvm-lipo -thin" printed a reasonable error message before dumping usage. Apple lipo will print "missing argument to -thin option"

Another difference is llvm-lipo will not validate the arch until all arguments are received, whereas Apple lipo will validate archs immediately. ("lipo -arch asdf")

Would be nice if "llvm-lipo" printed a list of valid archs when the arch is invalid. Currently it prints "llvm-lipo: error: Invalid architecture: asdf" and it exits. Apple lipo prints "unknown architecture specification flag: asdf in specifying thin operation: -thin asdf. known architecture flags are: ..."

PLEASE FIX: llvm-lipo does not support using "-o" in place of "-output"

Note: "llvm-lipo" does not work properly with certain Mach-O executables, such as those built with the -hideARM64 flag.

Fixed most of these issues, but for printing a list of knows architectures I am planning to make a change in a separate diff that returns a list of valid architectures, since I will no longer be modifying llvm-lipo code.

For the MachO executables built with -hideARM64 flag, I filed a bug for MachOUniversalBinary: https://bugs.llvm.org/show_bug.cgi?id=42343.

[mtrent]

In D63341#1552257, @anushabasana wrote:

In D63341#1549652, @mtrent wrote:

Note: "llvm-lipo" does not work properly with certain Mach-O executables, such as those built with the -hideARM64 flag.

Fixed most of these issues, but for printing a list of knows architectures I am planning to make a change in a separate diff that returns a list of valid architectures, since I will no longer be modifying llvm-lipo code.

For the MachO executables built with -hideARM64 flag, I filed a bug for MachOUniversalBinary: https://bugs.llvm.org/show_bug.cgi?id=42343.

Sounds good. Note that it's relevant for all lipo flags, not just '-thin'

[smeenai]

LGTM

llvm/tools/llvm-lipo/llvm-lipo.cpp

95

Nit: you can just move the function instead of adding a prototype.

104

Nit: StringRef should be enough to trigger the Twine construction and is more efficient here.

[anushabasana]

Fixed small review comments

[smeenai]

In D63341#1552257, @anushabasana wrote:

In D63341#1549652, @mtrent wrote:

Would be nice if "llvm-lipo -thin" printed a reasonable error message before dumping usage. Apple lipo will print "missing argument to -thin option"

Another difference is llvm-lipo will not validate the arch until all arguments are received, whereas Apple lipo will validate archs immediately. ("lipo -arch asdf")

Would be nice if "llvm-lipo" printed a list of valid archs when the arch is invalid. Currently it prints "llvm-lipo: error: Invalid architecture: asdf" and it exits. Apple lipo prints "unknown architecture specification flag: asdf in specifying thin operation: -thin asdf. known architecture flags are: ..."

PLEASE FIX: llvm-lipo does not support using "-o" in place of "-output"

Note: "llvm-lipo" does not work properly with certain Mach-O executables, such as those built with the -hideARM64 flag.

Fixed most of these issues, but for printing a list of knows architectures I am planning to make a change in a separate diff that returns a list of valid architectures, since I will no longer be modifying llvm-lipo code.

D63735 implements the nicer error message for an invalid architecture.

llvm/test/tools/llvm-lipo/Inputs/i386-slice.yaml

+--- !mach-o
+FileHeader:      
+  magic:           0xFEEDFACE
+  cputype:         0x00000007
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+    - ''
+...

llvm/test/tools/llvm-lipo/Inputs/i386-x86_64-universal.yaml

+--- !fat-mach-o
+FatHeader:       
+  magic:           0xCAFEBABE
+  nfat_arch:       2
+FatArchs:        
+  - cputype:         0x00000007
+    cpusubtype:      0x00000003
+    offset:          0x0000000000001000
+    size:            432
+    align:           12
+  - cputype:         0x01000007
+    cpusubtype:      0x00000003
+    offset:          0x0000000000002000
+    size:            488
+    align:           12
+Slices:          
+  - !mach-o
+    FileHeader:      
+      magic:           0xFEEDFACE
+      cputype:         0x00000007
+      cpusubtype:      0x00000003
+      filetype:        0x00000001
+      ncmds:           4
+      sizeofcmds:      312
+      flags:           0x00002000
+    LoadCommands:    
+      - cmd:             LC_SEGMENT
+        cmdsize:         192
+        segname:         ''
+        vmaddr:          0
+        vmsize:          72
+        fileoff:         340
+        filesize:        72
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+        version:         656384
+        sdk:             0
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+        - ''
+  - !mach-o
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+        - ''
+...

llvm/test/tools/llvm-lipo/help-error-messages.test

 # RUN: llvm-lipo -h | FileCheck --check-prefix=LIPO-USAGE %s
 # RUN: llvm-lipo --help | FileCheck --check-prefix=LIPO-USAGE %s
 
 # RUN: llvm-lipo -version | FileCheck --check-prefix=LIPO-VERSION %s
 # RUN: llvm-lipo --version | FileCheck --check-prefix=LIPO-VERSION %s
 
 # RUN: not llvm-lipo 2>&1 | FileCheck --check-prefix=LIPO-USAGE %s
 # RUN: not llvm-lipo -abcabc 2>&1 | FileCheck --check-prefix=LIPO-UNKNOWN-ARG %s
 # RUN: not llvm-lipo --abcabc 2>&1 | FileCheck --check-prefix=LIPO-UNKNOWN-ARG %s
 
 # RUN: not llvm-lipo %t -archs -verify_arch i386 2>&1 | FileCheck --check-prefix=MULTIPLE_FLAGS %s
-# MULTIPLE_FLAGS: only one of the following actions can be specified: -archs -verify_arch
+# RUN: not llvm-lipo %t -archs -thin i386 2>&1 | FileCheck --check-prefix=MULTIPLE_FLAGS %s
+# RUN: not llvm-lipo %t -thin i386 -verify_arch i386 2>&1 | FileCheck --check-prefix=MULTIPLE_FLAGS %s
+# RUN: not llvm-lipo %t -archs -thin i386 -verify_arch i386 2>&1 | FileCheck --check-prefix=MULTIPLE_FLAGS %s
+# MULTIPLE_FLAGS: only one of the following actions can be specified:
 
 # LIPO-USAGE:    USAGE: llvm-lipo
 # LIPO-UNKNOWN-ARG:    unknown argument '{{-+}}abcabc'
 # LIPO-VERSION: {{ version }}

llvm/test/tools/llvm-lipo/thin-executable-universal-binary.test

+# Executable testing is not supported on Windows, since all files are considered executable
+# UNSUPPORTED: windows
+# RUN: yaml2obj %s > %t-universal.o
+
+# RUN: chmod -x %t-universal.o
+# RUN: llvm-lipo %t-universal.o -thin i386 -output %t32.o
+# RUN: test ! -x %t32.o
+
+# RUN: chmod +x %t-universal.o
+# RUN: llvm-lipo %t-universal.o -thin i386 -output %t32-ex.o
+# RUN: test -x %t32-ex.o
+
+
+
+--- !fat-mach-o
+FatHeader:
+  magic:           0xCAFEBABE
+  nfat_arch:       2
+FatArchs:
+  - cputype:         0x00000007
+    cpusubtype:      0x00000003
+    offset:          0x0000000000001000
+    size:            28
+    align:           12
+  - cputype:         0x01000007
+    cpusubtype:      0x00000003
+    offset:          0x0000000000002000
+    size:            32
+    align:           12
+Slices:
+  - !mach-o
+    FileHeader:
+      magic:           0xFEEDFACE
+      cputype:         0x00000007
+      cpusubtype:      0x00000003
+      filetype:        0x00000001
+      ncmds:           0
+      sizeofcmds:      0
+      flags:           0x00002000
+  - !mach-o
+    FileHeader:
+      magic:           0xFEEDFACF
+      cputype:         0x01000007
+      cpusubtype:      0x00000003
+      filetype:        0x00000001
+      ncmds:           0
+      sizeofcmds:      0
+      flags:           0x00002000
+      reserved:        0x00000000
+...

llvm/test/tools/llvm-lipo/thin-macho-binary.test

+# RUN: yaml2obj %s > %t
+
+# RUN: not llvm-lipo %t -thin i386 2>&1 | FileCheck --check-prefix=NO_OUTPUT %s
+# NO_OUTPUT: error: thin expects a single output file
+
+# RUN: not llvm-lipo %t %t -thin i386 2>&1 | FileCheck --check-prefix=MULTIPLE_INPUT_OBJ %s
+# MULTIPLE_INPUT_OBJ: thin expects a single input file
+
+# RUN: not llvm-lipo %t -thin i386 -output %t.out 2>&1 | FileCheck --check-prefix=INPUT_FILE_THIN %s
+# INPUT_FILE_THIN: must be a fat file when the -thin option is specified
+
+--- !mach-o
+FileHeader:
+  magic:           0xFEEDFACE
+  cputype:         0x00000097
+  cpusubtype:      0x00000003
+  filetype:        0x00000001
+  ncmds:           0
+  sizeofcmds:      0
+  flags:           0x00002000
+...

llvm/test/tools/llvm-lipo/thin-universal-binary.test

+# RUN: yaml2obj %s > %t
+
+# RUN: not llvm-lipo %t -thin arc -output %t.out 2>&1 | FileCheck --check-prefix=ARCH_NOT_IN_FILE %s
+# ARCH_NOT_IN_FILE: does not contain the specified architecture arc to thin it to
+
+# RUN: not llvm-lipo %t -thin aarch101 -output %t.out 2>&1 | FileCheck --check-prefix=INVALID_ARCH %s
+# INVALID_ARCH: Invalid architecture: aarch101
+
+# RUN: yaml2obj %p/Inputs/i386-x86_64-universal.yaml > %t-universal.o
+# RUN: llvm-lipo %t-universal.o -thin i386 -output %t32.o
+# RUN: yaml2obj %p/Inputs/i386-slice.yaml > %t-basic32.o
+# RUN: cmp %t32.o %t-basic32.o
+
+--- !fat-mach-o
+FatHeader:
+  magic:           0xCAFEBABE
+  nfat_arch:       2
+FatArchs:
+  - cputype:         0x00000007
+    cpusubtype:      0x00000003
+    offset:          0x0000000000001000
+    size:            28
+    align:           12
+  - cputype:         0x01000007
+    cpusubtype:      0x00000003
+    offset:          0x0000000000002000
+    size:            32
+    align:           12
+Slices:
+  - !mach-o
+    FileHeader:
+      magic:           0xFEEDFACE
+      cputype:         0x00000007
+      cpusubtype:      0x00000003
+      filetype:        0x00000001
+      ncmds:           0
+      sizeofcmds:      0
+      flags:           0x00002000
+  - !mach-o
+    FileHeader:
+      magic:           0xFEEDFACF
+      cputype:         0x01000007
+      cpusubtype:      0x00000003
+      filetype:        0x00000001
+      ncmds:           0
+      sizeofcmds:      0
+      flags:           0x00002000
+      reserved:        0x00000000
+...

llvm/tools/llvm-lipo/LipoOpts.td

def verify_arch
     : Option<["-", "--"], "verify_arch", KIND_REMAINING_ARGS>,
       Group<action_group>,
       HelpText<
           "Verify that the specified arch_types are present in the input file">;
 
 def archs : Option<["-", "--"], "archs", KIND_FLAG>,
             Group<action_group>,
             HelpText<"Display the arch_types present in the input file">;
+
+def thin : Option<["-", "--"], "thin", KIND_SEPARATE>,
+           Group<action_group>,
+           HelpText<"Create a thin output file of specified arch_type from the "
+                    "fat input file. Requires -output option">;
+
+def output : Option<["-", "--"], "output", KIND_SEPARATE>,
+             HelpText<"Create output file with specified name">;

llvm/tools/llvm-lipo/llvm-lipo.cpp

 #include "llvm/Object/Binary.h"
 #include "llvm/Object/MachO.h"
 #include "llvm/Object/MachOUniversal.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Error.h"
+#include "llvm/Support/FileOutputBuffer.h"
 #include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/WithColor.h"
 
 using namespace llvm;
 using namespace llvm::object;
 
 static const StringRef ToolName = "llvm-lipo";
 

 class LipoOptTable : public opt::OptTable {
 public:
   LipoOptTable() : OptTable(LipoInfoTable) {}
 };
 
 enum class LipoAction {
   PrintArchs,
   VerifyArch,
+  ThinArch,
 };
 
 struct Config {
   SmallVector<std::string, 1> InputFiles;
   SmallVector<std::string, 1> VerifyArchList;
+  std::string ThinArchType;
+  std::string OutputFile;
   LipoAction ActionToPerform;
 };
 
 } // end namespace
 
 static Config parseLipoOptions(ArrayRef<const char *> ArgsArr) {
   Config C;
   LipoOptTable T;
   unsigned MissingArgumentIndex, MissingArgumentCount;
   llvm::opt::InputArgList InputArgs =
       T.ParseArgs(ArgsArr, MissingArgumentIndex, MissingArgumentCount);
 
   if (InputArgs.size() == 0) {
     // PrintHelp does not accept Twine.
     T.PrintHelp(errs(), "llvm-lipo input[s] option[s]", "llvm-lipo");
     exit(EXIT_FAILURE);
   }
 
   if (InputArgs.hasArg(LIPO_help)) {
     // PrintHelp does not accept Twine.
     T.PrintHelp(outs(), "llvm-lipo input[s] option[s]", "llvm-lipo");
     exit(EXIT_SUCCESS);
   }
 
   if (InputArgs.hasArg(LIPO_version)) {
     outs() << ToolName + "\n";
     cl::PrintVersionMessage();
     exit(EXIT_SUCCESS);
   }
 
   for (auto Arg : InputArgs.filtered(LIPO_UNKNOWN))
     reportError("unknown argument '" + Arg->getAsString(InputArgs) + "'");
 
   for (auto Arg : InputArgs.filtered(LIPO_INPUT))
     C.InputFiles.push_back(Arg->getValue());
   if (C.InputFiles.empty())
     reportError("at least one input file should be specified");
 
+  if (InputArgs.hasArg(LIPO_output))
+    C.OutputFile = InputArgs.getLastArgValue(LIPO_output);
+
   SmallVector<opt::Arg *, 1> ActionArgs(InputArgs.filtered(LIPO_action_group));
   if (ActionArgs.empty())
     reportError("at least one action should be specified");
   if (ActionArgs.size() > 1) {
     std::string Buf;
     raw_string_ostream OS(Buf);
     OS << "only one of the following actions can be specified:";
     for (auto Arg : ActionArgs)
case LIPO_verify_arch:
     return C;
 
   case LIPO_archs:
     if (C.InputFiles.size() > 1)
       reportError("archs expects a single input file");
     C.ActionToPerform = LipoAction::PrintArchs;
     return C;
 
+  case LIPO_thin:
+    if (C.InputFiles.size() > 1)
+      reportError("thin expects a single input file");
+    if (C.OutputFile.empty())
+      reportError("thin expects a single output file");
+    C.ThinArchType = ActionArgs[0]->getValue();
+    C.ActionToPerform = LipoAction::ThinArch;
+    return C;
+
   default:
     reportError("llvm-lipo action unspecified");
   }
 }
 
 static SmallVector<OwningBinary<Binary>, 1>
 readInputBinaries(ArrayRef<std::string> InputFiles) {
   SmallVector<OwningBinary<Binary>, 1> InputBinaries;
   for (StringRef InputFile : InputFiles) {
     Expected<OwningBinary<llvm::object::Binary>> BinaryOrErr =
         createBinary(InputFile);
     if (!BinaryOrErr)
       reportError(InputFile, BinaryOrErr.takeError());
-    if (!isa<MachOObjectFile>(BinaryOrErr->getBinary()) &&
-        !isa<MachOUniversalBinary>(BinaryOrErr->getBinary()))
+    // TODO: Add compatibility for archive files
+    if (BinaryOrErr->getBinary()->isArchive())
+      reportError("File " + InputFile +
+                  " is an archive file and is not yet supported.");
+    if (!BinaryOrErr->getBinary()->isMachO() &&
+        !BinaryOrErr->getBinary()->isMachOUniversalBinary())
       reportError("File " + InputFile + " has unsupported binary format");
     InputBinaries.push_back(std::move(*BinaryOrErr));
   }
   return InputBinaries;
 }
 
+static void validateArchitectureName(StringRef ArchitectureName) {
+  if (Triple(ArchitectureName).getArch() == Triple::ArchType::UnknownArch)
+    reportError("Invalid architecture: " + ArchitectureName);
+}
+
 LLVM_ATTRIBUTE_NORETURN
 static void verifyArch(ArrayRef<OwningBinary<Binary>> InputBinaries,
                        ArrayRef<std::string> VerifyArchList) {
   assert(!VerifyArchList.empty() &&
          "The list of architectures should be non-empty");
   assert(InputBinaries.size() == 1 && "Incorrect number of input binaries");
 
   for (StringRef Arch : VerifyArchList)
-    if (Triple(Arch).getArch() == Triple::ArchType::UnknownArch)
-      reportError("Invalid architecture: " + Arch);
+    validateArchitectureName(Arch);
 
   if (auto UO =
           dyn_cast<MachOUniversalBinary>(InputBinaries.front().getBinary())) {
     for (StringRef Arch : VerifyArchList) {
       Expected<std::unique_ptr<MachOObjectFile>> Obj =
           UO->getObjectForArch(Arch);
       if (!Obj)
         exit(EXIT_FAILURE);
static void printArchs(ArrayRef<OwningBinary<Binary>> InputBinaries) {
   } else {
     llvm_unreachable("Unexpected binary format");
   }
 
   outs() << "\n";
   exit(EXIT_SUCCESS);
 }
 
+LLVM_ATTRIBUTE_NORETURN
+static void extractSlice(ArrayRef<OwningBinary<Binary>> InputBinaries,
+                         StringRef ThinArchType, StringRef OutputFileName) {
+  assert(!ThinArchType.empty() && "The architecture type should be non-empty");
+  assert(InputBinaries.size() == 1 && "Incorrect number of input binaries");
+  assert(!OutputFileName.empty() && "Thin expects a single output file");
+
+  validateArchitectureName(ThinArchType);
+
+  if (InputBinaries.front().getBinary()->isMachO()) {
+    reportError("input file " +
+                InputBinaries.front().getBinary()->getFileName() +
+                " must be a fat file when the -thin option is specified");
+    exit(EXIT_FAILURE);
+  }
+
+  auto *UO = cast<MachOUniversalBinary>(InputBinaries.front().getBinary());
+  Expected<std::unique_ptr<MachOObjectFile>> Obj =
+      UO->getObjectForArch(ThinArchType);
+  if (!Obj)
+    reportError("fat input file " + UO->getFileName() +
+                " does not contain the specified architecture " + ThinArchType +
+                " to thin it to");
+
+  Expected<std::unique_ptr<FileOutputBuffer>> OutFileOrError =
+      FileOutputBuffer::create(OutputFileName,
+                               Obj.get()->getMemoryBufferRef().getBufferSize(),
+                               sys::fs::can_execute(UO->getFileName())
+                                   ? FileOutputBuffer::F_executable
+                                   : 0);
+  if (!OutFileOrError)
+    reportError(OutputFileName, OutFileOrError.takeError());
+  std::copy(Obj.get()->getMemoryBufferRef().getBufferStart(),
+            Obj.get()->getMemoryBufferRef().getBufferEnd(),
+            OutFileOrError.get()->getBufferStart());
+  if (OutFileOrError.get()->commit())
+    reportError(OutputFileName, OutFileOrError.get()->commit());
+  exit(EXIT_SUCCESS);
+}
+
 int main(int argc, char **argv) {
   InitLLVM X(argc, argv);
   Config C = parseLipoOptions(makeArrayRef(argv + 1, argc));
   SmallVector<OwningBinary<Binary>, 1> InputBinaries =
       readInputBinaries(C.InputFiles);
 
   switch (C.ActionToPerform) {
   case LipoAction::VerifyArch:
     verifyArch(InputBinaries, C.VerifyArchList);
     break;
   case LipoAction::PrintArchs:
     printArchs(InputBinaries);
     break;
+  case LipoAction::ThinArch:
+    extractSlice(InputBinaries, C.ThinArchType, C.OutputFile);
+    break;
   }
   return EXIT_SUCCESS;
 }