[lld] f741815 - [lld][ELF] Fix lazy ThinLTO index writing in thin archives

[Aiden Grossman via llvm-commits]

Author: Aiden Grossman
Date: 2022-10-05T17:12:15Z
New Revision: f741815ddb49e3ed26de327a51ccf60f66f21d46

URL: https://github.com/llvm/llvm-project/commit/f741815ddb49e3ed26de327a51ccf60f66f21d46
DIFF: https://github.com/llvm/llvm-project/commit/f741815ddb49e3ed26de327a51ccf60f66f21d46.diff

LOG: [lld][ELF] Fix lazy ThinLTO index writing in thin archives

Currently when the --thinlto-emit-index-files is used with LLD and a
thin archive is passed containing references to object files to link
against where the object files are in a different folder than the thin
archive and some of the archives aren't linked against (ie stay lazy),
the empty index file writer ends up trying to write to a path that
doesn't exist. This patch changes the behavior of that function to use
the path of the obj member of the BitcodeFile object rather than just
the path of the BitcodeFile object itself, which matches the behavior of
the default (non-lazy) case.

Fixes #57963

Regression test added.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D135014

Added: 
    lld/test/ELF/lto/thinlto-emit-index-thin-archive.ll

Modified: 
    lld/ELF/LTO.cpp

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


################################################################################
diff  --git a/lld/ELF/LTO.cpp b/lld/ELF/LTO.cpp
index de0f8316a2991..ab04748b76afa 100644
--- a/lld/ELF/LTO.cpp
+++ b/lld/ELF/LTO.cpp
@@ -301,7 +301,8 @@ static void thinLTOCreateEmptyIndexFiles() {
       continue;
     if (linkedBitCodeFiles.contains(f->getName()))
       continue;
-    std::string path = replaceThinLTOSuffix(getThinLTOOutputFile(f->getName()));
+    std::string path =
+        replaceThinLTOSuffix(getThinLTOOutputFile(f->obj->getName()));
     std::unique_ptr<raw_fd_ostream> os = openFile(path + ".thinlto.bc");
     if (!os)
       continue;

diff  --git a/lld/test/ELF/lto/thinlto-emit-index-thin-archive.ll b/lld/test/ELF/lto/thinlto-emit-index-thin-archive.ll
new file mode 100644
index 0000000000000..bcb90e21a8721
--- /dev/null
+++ b/lld/test/ELF/lto/thinlto-emit-index-thin-archive.ll
@@ -0,0 +1,49 @@
+; REQUIRES: x86
+
+; RUN: rm -rf %t.dir && mkdir %t.dir && cd %t.dir
+; RUN: mkdir dir1 dir2
+; RUN: llvm-as %s -o ./dir1/main.o
+; RUN: llvm-as %p/Inputs/thinlto.ll -o ./dir1/unused.o
+; RUN: llvm-as %p/Inputs/thin1.ll -o ./dir1/thin.o
+; RUN: llvm-as %p/Inputs/thin2.ll -o ./dir2/thin.o
+; RUN: llvm-ar crT ./dir2/lib.a dir1/unused.o dir1/thin.o dir2/thin.o
+
+;; For a thin archive referencing object files in a 
diff erent directory,
+;; emit index files (lib.a($member at $offset).thinlto.bc) in the directory
+;; containing the archive, even in the lazy case. The information about the
+;; referenced member's directory is lost.
+; RUN: ld.lld --thinlto-emit-index-files ./dir2/lib.a ./dir1/main.o -o c --save-temps
+; RUN: ls ./dir2 | FileCheck %s --check-prefix CHECK-UNUSED
+
+; CHECK-UNUSED: lib.a(unused.o at {{[1-9][0-9]+}})
+
+;; Index files emitted from object files in a thin archive should have the
+;; offset in the archive specified to avoid collisions
+; RUN: FileCheck %s < c.resolution.txt --check-prefix CHECK-COLLISION
+
+; CHECK-COLLISION: dir1/main.o
+; CHECK-COLLISION: dir2/lib.a(thin.o at {{[1-9][0-9]+}})
+; CHECK-COLLISION-NEXT: -r=./dir2/lib.a(thin.o at {{[1-9][0-9]+}}),blah,pl
+; CHECK-COLLISION: dir2/lib.a(thin.o at {{[1-9][0-9]+}})
+; CHECK-COLLISION-NEXT: -r=./dir2/lib.a(thin.o at {{[1-9][0-9]+}}),foo,pl
+
+;; Clean up
+; RUN: rm -rf ./dir1/*.thinlto.bc
+; RUN: rm -rf ./dir2/*.thinlto.bc
+;; Empty index files for unused files in thin archives should still be emitted
+;; in the same format when using --whole-archive
+; RUN: ld.lld --thinlto-emit-index-files --whole-archive ./dir2/lib.a ./dir1/main.o -o d
+; RUN: ls ./dir2 | FileCheck %s --check-prefix CHECK-UNUSED
+
+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 i32 @blah(i32 %meh)
+declare i32 @foo(i32 %goo)
+
+define void @_start() {
+entry:
+  call i32 @foo(i32 0)
+  call i32 @blah(i32 0)
+  ret void
+}

diff  --git a/lld/test/ELF/lto/thinlto-thin-archive-collision.ll b/lld/test/ELF/lto/thinlto-thin-archive-collision.ll
deleted file mode 100644
index 1a175f29d369a..0000000000000
--- a/lld/test/ELF/lto/thinlto-thin-archive-collision.ll
+++ /dev/null
@@ -1,27 +0,0 @@
-; 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
-}