[lld/mac] Don't write mtimes to N_OSO entries if ZERO_AR_DATE is set.

[thakis]

Summary

This is important for build determinism. This matches ld64.

[thakis]

fix archive files

[int3]

lld/MachO/DriverUtils.cpp

266–267

nit: how about zeroModTime? It's true that modTime is only being used by the debug info, but we're changing how it's (not) being read as well, so it's a bit of a misnomer. Plus the name is pretty long :p

lld/test/MachO/stabs.s

52

if you changed this to a numeric substitution (like the line immediately below) you could specify a shorter -D#TEST_TIME=0 on the command line

[thakis]

Thanks!

lld/MachO/Config.h

struct Configuration {
 
   llvm::DenseMap<llvm::StringRef, SymbolPriorityEntry> priorities;
   SectionRenameMap sectionRenameMap;
   SegmentRenameMap segmentRenameMap;
 
   SymbolPatterns exportedSymbols;
   SymbolPatterns unexportedSymbols;
 
+  bool writeModTimeToDebugInfo = true;
+
   llvm::MachO::Architecture arch() const { return platformInfo.target.Arch; }
 
   llvm::MachO::PlatformKind platform() const {
     return platformInfo.target.Platform;
   }
 };
 
 // The symbol with the highest priority should be ordered first in the output

lld/MachO/Driver.cpp

bool macho::link(ArrayRef<const char *> argsArr, bool canExitEarly,
   config->runtimePaths = args::getStrings(args, OPT_rpath);
   config->allLoad = args.hasArg(OPT_all_load);
   config->forceLoadObjC = args.hasArg(OPT_ObjC);
   config->demangle = args.hasArg(OPT_demangle);
   config->implicitDylibs = !args.hasArg(OPT_no_implicit_dylibs);
   config->emitFunctionStarts = !args.hasArg(OPT_no_function_starts);
   config->emitBitcodeBundle = args.hasArg(OPT_bitcode_bundle);
 
+  // FIXME: Add a commandline flag for this too.
+  config->writeModTimeToDebugInfo = !getenv("ZERO_AR_DATE");
+
   std::array<PlatformKind, 3> encryptablePlatforms{
       PlatformKind::iOS, PlatformKind::watchOS, PlatformKind::tvOS};
   config->emitEncryptionInfo =
       args.hasFlag(OPT_encryptable, OPT_no_encryption,
                    is_contained(encryptablePlatforms, config->platform()));
 
 #ifndef LLVM_HAVE_LIBXAR
   if (config->emitBitcodeBundle)

lld/MachO/DriverUtils.cpp

StringRef macho::rerootPath(StringRef path) {
 
   return path;
 }
 
 Optional<InputFile *> macho::loadArchiveMember(MemoryBufferRef mb,
                                                uint32_t modTime,
                                                StringRef archiveName,
                                                bool objCOnly) {
   switch (identify_magic(mb.getBuffer())) {
   case file_magic::macho_object:
     if (!objCOnly || hasObjCSection(mb))
       return make<ObjFile>(mb, modTime, archiveName);
     return None;
   case file_magic::bitcode:
     if (!objCOnly || check(isBitcodeContainingObjCCategory(mb)))
       return make<BitcodeFile>(mb);
     return None;
   default:
     error(archiveName + ": archive member " + mb.getBufferIdentifier() +
           " has unhandled file type");
     return None;
   }
 }
 
 uint32_t macho::getModTime(StringRef path) {
+  if (!config->writeModTimeToDebugInfo)
+    return 0;
+
   fs::file_status stat;
   if (!fs::status(path, stat))
     if (fs::exists(stat))
       return toTimeT(stat.getLastModificationTime());
 
   warn("failed to get modification time of " + path);
   return 0;
 }

lld/test/MachO/stabs.s

 # REQUIRES: x86, shell
 # UNSUPPORTED: system-windows
 # RUN: rm -rf %t; split-file %s %t
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/test.s -o %t/test.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/foo.s -o %t/foo.o
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/no-debug.s -o %t/no-debug.o
 ## Set modtimes of the files for deterministic test output.
 # RUN: env TZ=UTC touch -t "197001010000.16" %t/test.o
 # RUN: env TZ=UTC touch -t "197001010000.32" %t/foo.o
 # RUN: llvm-ar rcsU %t/foo.a %t/foo.o
 
 # RUN: %lld -lSystem %t/test.o %t/foo.o %t/no-debug.o -o %t/test
 # RUN: (llvm-objdump --section-headers %t/test; dsymutil -s %t/test) | \
-# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.o
+# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.o \
+# RUN:       -DTEST_TIME=0000000000000010 -DFOO_TIME=0000000000000020
 
 ## Check that we emit the right modtime even when the object file is in an
 ## archive.
 # RUN: %lld -lSystem %t/test.o %t/foo.a %t/no-debug.o -o %t/test
 # RUN: (llvm-objdump --section-headers %t/test; dsymutil -s %t/test) | \
-# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.a\(foo.o\)
+# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.a\(foo.o\) \
+# RUN:       -DTEST_TIME=0000000000000010 -DFOO_TIME=0000000000000020
+
+## Check that we don't emit modtimes if ZERO_AR_DATE is set.
+# RUN: env ZERO_AR_DATE=1 %lld -lSystem %t/test.o %t/foo.o %t/no-debug.o \
+# RUN:     -o %t/test
+# RUN: (llvm-objdump --section-headers %t/test; dsymutil -s %t/test) | \
+# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.o \
+# RUN:       -DTEST_TIME=0000000000000000 -DFOO_TIME=0000000000000000
 
 ## Check that we emit absolute paths to the object files in our OSO entries
 ## even if our inputs are relative paths.
 # RUN: cd %t && %lld -lSystem test.o foo.o no-debug.o -o test
 # RUN: (llvm-objdump --section-headers %t/test; dsymutil -s %t/test) | \
-# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.o
+# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.o \
+# RUN:       -DTEST_TIME=0000000000000010 -DFOO_TIME=0000000000000020
 
 # RUN: cd %t && %lld -lSystem test.o foo.a no-debug.o -o %t/test
 # RUN: (llvm-objdump --section-headers %t/test; dsymutil -s %t/test) | \
-# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.a\(foo.o\)
+# RUN:   FileCheck %s -DDIR=%t -DFOO_PATH=%t/foo.a\(foo.o\) \
+# RUN:       -DTEST_TIME=0000000000000010 -DFOO_TIME=0000000000000020
 
 # CHECK:       Sections:
 # CHECK-NEXT:  Idx                Name
 # CHECK-NEXT:  [[#TEXT_ID:]]      __text
 # CHECK-NEXT:  [[#DATA_ID:]]      __data
 # CHECK-NEXT:  [[#MORE_DATA_ID:]] more_data
 # CHECK-NEXT:  [[#COMM_ID:]]      __common
 # CHECK-NEXT:  [[#MORE_TEXT_ID:]] more_text
 
 # CHECK:      (N_SO         ) 00                         0000   0000000000000000   '/tmp/test.cpp'
-# CHECK-NEXT: (N_OSO        ) 03                         0001   0000000000000010   '[[DIR]]/test.o'
+# CHECK-NEXT: (N_OSO        ) 03                         0001   [[TEST_TIME]]      '[[DIR]]/test.o'
 # CHECK-NEXT: (N_STSYM      ) [[#%.2d,MORE_DATA_ID + 1]] 0000   [[#%.16x,STATIC:]] '_static_var'
 # CHECK-NEXT: (N_FUN        ) [[#%.2d,TEXT_ID + 1]]      0000   [[#%.16x,MAIN:]]   '_main'
 # CHECK-NEXT: (N_FUN        ) 00                         0000   0000000000000006{{$}}
 # CHECK-NEXT: (N_FUN        ) [[#%.2d,TEXT_ID + 1]]      0000   [[#%.16x,BAR:]]    '_bar'
 # CHECK-NEXT: (N_FUN        ) 00                         0000   0000000000000000{{$}}
 # CHECK-NEXT: (N_FUN        ) [[#%.2d,TEXT_ID + 1]]      0000   [[#%.16x,BAR2:]]   '_bar2'
 # CHECK-NEXT: (N_FUN        ) 00                         0000   0000000000000001{{$}}
 # CHECK-NEXT: (N_FUN        ) [[#%.2d,TEXT_ID + 1]]      0000   [[#%.16x,BAZ:]]    '_baz'
 # CHECK-NEXT: (N_FUN        ) 00                         0000   0000000000000000{{$}}
 # CHECK-NEXT: (N_FUN        ) [[#%.2d,TEXT_ID + 1]]      0000   [[#%.16x,BAZ2:]]   '_baz2'
 # CHECK-NEXT: (N_FUN        ) 00                         0000   0000000000000002{{$}}
 # CHECK-NEXT: (N_FUN        ) [[#%.2d,TEXT_ID + 1]]      0000   [[#%.16x,QUX:]]    '_qux'
 # CHECK-NEXT: (N_FUN        ) 00                         0000   0000000000000003{{$}}
 # CHECK-NEXT: (N_FUN        ) [[#%.2d,TEXT_ID + 1]]      0000   [[#%.16x,QUUX:]]   '_quux'
 # CHECK-NEXT: (N_FUN        ) 00                         0000   0000000000000004{{$}}
 # CHECK-NEXT: (N_GSYM       ) [[#%.2d,DATA_ID + 1]]      0000   [[#%.16x,GLOB:]]   '_global_var'
 # CHECK-NEXT: (N_GSYM       ) [[#%.2d,COMM_ID + 1]]      0000   [[#%.16x,ZERO:]]   '_zero'
 # CHECK-NEXT: (N_FUN        ) [[#%.2d,MORE_TEXT_ID + 1]] 0000   [[#%.16x,FUN:]]    '_fun'
 # CHECK-NEXT: (N_FUN        ) 00                         0000   0000000000000001{{$}}
 # CHECK-NEXT: (N_SO         ) 01                         0000   0000000000000000{{$}}
 # CHECK-NEXT: (N_SO         ) 00                         0000   0000000000000000   '/foo.cpp'
-# CHECK-NEXT: (N_OSO        ) 03                         0001   0000000000000020   '[[FOO_PATH]]'
+# CHECK-NEXT: (N_OSO        ) 03                         0001   [[FOO_TIME]]       '[[FOO_PATH]]'
 # CHECK-NEXT: (N_FUN        ) [[#%.2d,TEXT_ID + 1]]      0000   [[#%.16x,FOO:]]    '_foo'
 # CHECK-NEXT: (N_FUN        ) 00                         0000   0000000000000001{{$}}
 # CHECK-NEXT: (N_SO         ) 01                         0000   0000000000000000{{$}}
 # CHECK-DAG:  (     SECT    ) [[#%.2d,MORE_DATA_ID + 1]] 0000   [[#STATIC]]        '_static_var'
 # CHECK-DAG:  (     SECT EXT) [[#%.2d,TEXT_ID + 1]]      0000   [[#MAIN]]          '_main'
 # CHECK-DAG:  (     ABS  EXT) 00                         0000   {{[0-9af]+}}       '_abs'
 # CHECK-DAG:  (     SECT EXT) [[#%.2d,TEXT_ID + 1]]      0000   [[#FOO]]           '_foo'
 # CHECK-DAG:  (     SECT EXT) [[#%.2d,TEXT_ID + 1]]      0000   [[#BAR]]           '_bar'