[LLD][ELF] Use offset in thin archives to disambiguate thinLTO members

[hoyFB]

Summary

This is fixing a thinLTO module collision issue for thin archives. The problem is that we always use a zero offset to name members in a thin archive and that causes the following build error:

ld.lld: error: Expected at most one ThinLTO module per bitcode file

which happens to a thin archive that has two members with the same object file name (whose paths will be ignored by thinLTO driver)

The fix here is to use real member offset instead as is done for non-thin archives.

[MaskRay]

lld/test/ELF/lto/thinlto-thinarchivecollision.ll

2 ↗

(On Diff #263755)

%T is currently deprecated.

You can use RUN: rm -fr %t && mkdir %t && cd %t and update the following lines to be relative to %t

23 ↗

(On Diff #263755)

Rename to _start to avoid --entry=main

28 ↗

(On Diff #263755)

No newline at end of file

[hoyFB]

Updating D79880: [LLD][ELF] Use offset in thin archives to disambiguate thinLTO members

lld/test/ELF/lto/thinlto-thinarchivecollision.ll

2 ↗

(On Diff #263755)

Good idea, it also simplifies the CHECK lines.

[MaskRay]

Looks good to me. Will be worth waiting a day or so to see if there are any further comments.

lld/test/ELF/lto/thinlto-thinarchivecollision.ll

1 ↗

(On Diff #263794)

thinlto-thin-archive-collision.ll

8 ↗

(On Diff #263794)

--save-temps

[hoyFB]

Updating D79880: [LLD][ELF] Use offset in thin archives to disambiguate thinLTO members

[hoyFB]

Updating D79880: [LLD][ELF] Use offset in thin archives to disambiguate thinLTO members

[hoyFB]

lld/test/ELF/lto/thinlto.ll

65

Attempting to make it work on Windows platform which looks like the diff time testing is performed on and with the failure:

$ ":" "RUN: at line 65"
$ "ls" "C:\ws\prod\llvm-project\build\tools\lld\test\ELF\lto\Output\thinlto.ll.tmp.dir/t.a\(t.o\" "at\" "*\).0.preopt.bc"
# command stderr:
s: C:\ws\prod\llvm-project\build\tools\lld\test\ELF\lto\Output\thinlto.ll.tmp.dir/t.a\(t.o\: No such file or directory
ls: at\: No such file or directory
l.s: *\).0.preopt.bc: Invalid argument

[ruiu]

LGTM

lld/test/ELF/lto/thinlto.ll

65

I think that on Windows only double-quotes are recognized as a quotation mark and single-quotes are just regular characters. So you can probably change ' to ". Using * is fine though.

lld/ELF/InputFiles.cpp

MemoryBufferRef mb =
       CHECK(c.getMemoryBufferRef(),
             toString(this) +
                 ": could not get the buffer for the member defining symbol " +
                 toELFString(sym));
 
   if (tar && c.getParent()->isThin())
     tar->append(relativeToRoot(CHECK(c.getFullName(), this)), mb.getBuffer());
 
-  InputFile *file = createObjectFile(
-      mb, getName(), c.getParent()->isThin() ? 0 : c.getChildOffset());
+  InputFile *file = createObjectFile(mb, getName(), c.getChildOffset());
   file->groupId = groupId;
   parseFile(file);
 }
 
 size_t ArchiveFile::getMemberCount() const {
   size_t count = 0;
   Error err = Error::success();
   for (const Archive::Child &c : file->children(err)) {

lld/test/ELF/lto/thinlto-thin-archive-collision.ll

+; REQUIRES: x86
+; RUN: rm -fr %t && mkdir %t && cd %t
+; RUN: mkdir thinlto-archives thinlto-archives/a thinlto-archives/b
+; RUN: opt -thinlto-bc -o thinlto-archives/main.o %s
+; RUN: opt -thinlto-bc -o thinlto-archives/a/thin.o %S/Inputs/thin1.ll
+; RUN: opt -thinlto-bc -o thinlto-archives/b/thin.o %S/Inputs/thin2.ll
+; RUN: llvm-ar qcT thinlto-archives/thin.a thinlto-archives/a/thin.o thinlto-archives/b/thin.o
+; RUN: ld.lld thinlto-archives/main.o thinlto-archives/thin.a -o thinlto-archives/main.exe --save-temps
+; RUN: FileCheck %s < thinlto-archives/main.exe.resolution.txt
+
+; CHECK: thinlto-archives/main.o
+; CHECK: thinlto-archives/thin.a(thin.o at {{[1-9][0-9]+}})
+; CHECK-NEXT: -r=thinlto-archives/thin.a(thin.o at {{[1-9][0-9]+}}),foo,pl
+; CHECK: thinlto-archives/thin.a(thin.o at {{[1-9][0-9]+}})
+; CHECK-NEXT: -r=thinlto-archives/thin.a(thin.o at {{[1-9][0-9]+}}),blah,pl
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-scei-ps4"
+
+declare i32 @blah(i32 %meh)
+declare i32 @foo(i32 %goo)
+
+define i32 @_start() {
+  call i32 @foo(i32 0)
+  call i32 @blah(i32 0)
+  ret i32 0
+}

lld/test/ELF/lto/thinlto.ll

 ; RUN: llvm-nm %t32.lto.o | FileCheck %s --check-prefix=NM2
 
 ; Check that -save-temps is usable with thin archives
 ; RUN: rm -fr %t.dir
 ; RUN: mkdir -p %t.dir
 ; RUN: cp %t2.o %t.dir/t.o
 ; RUN: llvm-ar rcsT %t.dir/t.a %t.dir/t.o
 ; RUN: ld.lld -save-temps %t1.o %t.dir/t.a -o %t.null
-; RUN: ls '%t.dir/t.a(t.o at 0).0.preopt.bc'
+; RUN: ls %t.dir/t.a*.0.preopt.bc
 
 ; NM1: T f
 ; NM2: T g
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 declare void @g(...)
 
 define void @f() {
 entry:
   call void (...) @g()
   ret void
 }