[LLD][COFF] Add index to disambiguate archive members when using -wholearchive

[zero9178]

Summary

PR42951:
When linking an archive with members that have the same name linking fails when using the -wholearchive option. This patch passes the index of the member in the archive to the offset parameter to disambiguate the member.

[zero9178]

Fixed test to show regression and verify output

[ruiu]

COFF/Driver.cpp

191 ↗

(On Diff #215217)

Just int would probably be better.

test/COFF/thinlto-whole-archives.ll

13–18 ↗

(On Diff #215217)

This may break Windows buildbot on which path components are separated not by / but by \.

[zero9178]

Changed index from std::uint64_t to int. Made test accept both kinds of slashes

[ruiu]

LGTM with this change.

COFF/Driver.cpp

191 ↗

(On Diff #218064)

Another nit: memberIndex is better than memberOffset because offset implies that that variable contains a distance from the beginning of the file and a current member (which does not always increment by one).

[zero9178]

Changed memberOffset to memberIndex as suggested by reviwer. Would need someone to commit this for me

[zero9178]

Friendly after a week ping.

lld/trunk/COFF/Driver.cpp

case file_magic::windows_resource:
     break;
   case file_magic::archive:
     if (wholeArchive) {
       std::unique_ptr<Archive> file =
           CHECK(Archive::create(mbref), filename + ": failed to parse archive");
       Archive *archive = file.get();
       make<std::unique_ptr<Archive>>(std::move(file)); // take ownership
 
+      int memberIndex = 0;
       for (MemoryBufferRef m : getArchiveMembers(archive))
-        addArchiveBuffer(m, "<whole-archive>", filename, 0);
+        addArchiveBuffer(m, "<whole-archive>", filename, memberIndex++);
       return;
     }
     symtab->addFile(make<ArchiveFile>(mbref));
     break;
   case file_magic::bitcode:
     if (lazy)
       symtab->addFile(make<LazyObjFile>(mbref));
     else

lld/trunk/test/COFF/thinlto-whole-archives.ll

+; REQUIRES: x86
+; RUN: rm -fr %T/thinlto-whole-archives
+; RUN: mkdir %T/thinlto-whole-archives %T/thinlto-whole-archives/a %T/thinlto-whole-archives/b
+; RUN: opt -thinlto-bc -o %T/thinlto-whole-archives/main.obj %s
+; RUN: opt -thinlto-bc -o %T/thinlto-whole-archives/a/bar.obj %S/Inputs/lto-dep.ll
+; RUN: opt -thinlto-bc -o %T/thinlto-whole-archives/b/bar.obj %S/Inputs/bar.ll
+; RUN: llvm-ar crs %T/thinlto-whole-archives/a.lib %T/thinlto-whole-archives/a/bar.obj %T/thinlto-whole-archives/b/bar.obj
+; RUN: lld-link -out:%T/thinlto-whole-archives/main.exe -entry:main \
+; RUN:     -wholearchive -lldsavetemps -subsystem:console %T/thinlto-whole-archives/main.obj \
+; RUN:     %T/thinlto-whole-archives/a.lib
+; RUN: FileCheck %s < %T/thinlto-whole-archives/main.exe.resolution.txt
+
+; CHECK: {{[/\\]thinlto-whole-archives[/\\]main.obj$}}
+; CHECK: {{^-r=.*[/\\]thinlto-whole-archives[/\\]main.obj,main,px$}}
+; CHECK: {{[/\\]thinlto-whole-archives[/\\]a.libbar.obj[0-9]+$}}
+; CHECK-NEXT: {{^-r=.*[/\\]thinlto-whole-archives[/\\]a.libbar.obj[0-9]+,foo,p$}}
+; CHECK-NEXT: {{[/\\]thinlto-whole-archives[/\\]a.libbar.obj[0-9]+$}}
+; CHECK-NEXT: {{^-r=.*[/\\]thinlto-whole-archives[/\\]a.libbar.obj[0-9]+,bar,p$}}
+
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc"
+
+declare void @bar()
+declare void @foo()
+
+define i32 @main() {
+  call void @foo()
+  call void @bar()
+  ret i32 0
+}