[lld-macho] Tweak the names we give to archive members

[int3]

Summary

In particular, make it foo.a(foo.o)$ARCHIVE_OFFSET. The goal is to
make it more similar to both ld64 implementation, which uses the
foo.a(foo.o)$MODULE_ID format. We dump some of these names in LTO
code, so matching ld64's format is helpful. This format is also more
similar to LLD-ELF's, which is foo.a(foo.o at $ARCHIVE_OFFSET).

[kyulee]

LGTM

[oontvoo]

LG!

(FWIW, I think ELF's format is more human-readable ... perhaps if consistency were the goal, we should choose to be consistent with other LLD ports? /shrug)

[int3]

I agree it's more readable but following ld64 is more useful for us 😅

also LLD-COFF doesn't match LLD-ELF's format either

lld/MachO/InputFiles.cpp

BitcodeFile::BitcodeFile(MemoryBufferRef mb, StringRef archiveName,
   // name. If two members with the same name are provided, this causes a
   // collision and ThinLTO can't proceed.
   // So, we append the archive name to disambiguate two members with the same
   // name from multiple different archives, and offset within the archive to
   // disambiguate two members of the same name from a single archive.
   MemoryBufferRef mbref(mb.getBuffer(),
                         saver().save(archiveName.empty()
                                          ? path
-                                         : archiveName +
-                                               sys::path::filename(path) +
+                                         : archiveName + "(" +
+                                               sys::path::filename(path) + ")" +
                                                utostr(offsetInArchive)));
-
   obj = check(lto::InputFile::create(mbref));
   if (lazy)
     parseLazy();
   else
     parse();
 }
 
 void BitcodeFile::parse() {

lld/test/MachO/lto-archivecollision.ll

 ; REQUIRES: x86
 ; RUN: rm -rf %t; split-file %s %t
 ; RUN: mkdir %t/a %t/b
 ; RUN: opt -thinlto-bc -o %t/main.o %t/main.ll
 ; RUN: opt -thinlto-bc -o %t/a/bar.o %t/foo.ll
 ; RUN: opt -thinlto-bc -o %t/b/bar.o %t/bar.ll
 ; RUN: llvm-ar crs %t/libbar.a %t/a/bar.o %t/b/bar.o
 ; RUN: %lld -save-temps %t/main.o %t/libbar.a -o %t/test
 ; RUN: FileCheck %s --check-prefix=SAME-ARCHIVE < %t/test.resolution.txt
 
 ; RUN: llvm-ar crs %t/liba.a %t/a/bar.o
 ; RUN: llvm-ar crs %t/libb.a %t/b/bar.o
 ; RUN: %lld -save-temps %t/main.o %t/liba.a %t/libb.a -o %t/test
 ; RUN: FileCheck %s --check-prefix=DIFFERENT-ARCHIVES < %t/test.resolution.txt
 
-; SAME-ARCHIVE: libbar.abar.o[[#OFFSET:]]
-; SAME-ARCHIVE-NEXT: -r={{.*}}/libbar.abar.o[[#OFFSET:]],_foo,p
-; SAME-ARCHIVE-NEXT: libbar.abar.o[[#OTHEROFFSET:]]
-; SAME-ARCHIVE-NEXT: -r={{.*}}/libbar.abar.o[[#OTHEROFFSET:]],_bar,p
-
-; DIFFERENT-ARCHIVES: liba.abar.o[[#OFFSET:]]
-; DIFFERENT-ARCHIVES-NEXT: -r={{.*}}/liba.abar.o[[#OFFSET:]],_foo,p
-; DIFFERENT-ARCHIVES-NEXT: libb.abar.o[[#OTHEROFFSET:]]
-; DIFFERENT-ARCHIVES-NEXT: -r={{.*}}/libb.abar.o[[#OTHEROFFSET:]],_bar,p
+; SAME-ARCHIVE: libbar.a(bar.o)[[#OFFSET:]]
+; SAME-ARCHIVE-NEXT: -r={{.*}}/libbar.a(bar.o)[[#OFFSET:]],_foo,p
+; SAME-ARCHIVE-NEXT: libbar.a(bar.o)[[#OTHEROFFSET:]]
+; SAME-ARCHIVE-NEXT: -r={{.*}}/libbar.a(bar.o)[[#OTHEROFFSET:]],_bar,p
+
+; DIFFERENT-ARCHIVES: liba.a(bar.o)[[#OFFSET:]]
+; DIFFERENT-ARCHIVES-NEXT: -r={{.*}}/liba.a(bar.o)[[#OFFSET:]],_foo,p
+; DIFFERENT-ARCHIVES-NEXT: libb.a(bar.o)[[#OTHEROFFSET:]]
+; DIFFERENT-ARCHIVES-NEXT: -r={{.*}}/libb.a(bar.o)[[#OTHEROFFSET:]],_bar,p
 
 ;--- main.ll
 
 target triple = "x86_64-apple-macosx10.15.0"
 target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 
 declare void @bar()
 declare void @foo()