[lld] [LLD][COFF] Make /wholearchive thin-archive member identifiers consistent (PR #145487)

via llvm-commits llvm-commits at lists.llvm.org
Mon Jul 21 07:29:40 PDT 2025


https://github.com/bd1976bris updated https://github.com/llvm/llvm-project/pull/145487

>From 7c8c158fadfad58a89754e709516469d5d1c8ac9 Mon Sep 17 00:00:00 2001
From: Dunbobbin <Ben.Dunbobbin at sony.com>
Date: Tue, 24 Jun 2025 10:20:35 +0100
Subject: [PATCH 1/5] [LLD][COFF] Make /wholearchive thin-archive member
 identifiers consistent

A thin archive is an archive/library format where the archive itself
contains only references to member object files on disk, rather than
embedding the file contents.

For the non-/wholearchive case, we use the path to the archive member
as the identifier for thin-archive members (see comments in
`enqueueArchiveMember`). This patch modifies the /wholearchive path to
behave the same way.

Apart from consistency, my motivation for fixing this is DTLTO
(https://github.com/llvm/llvm-project/pull/126654), where having the
member identifier be the path on disk allows distribution of bitcode
members during ThinLTO.
---
 lld/COFF/Driver.cpp          |  7 ++++++-
 lld/test/COFF/thin-archive.s | 39 +++++++++++++++++++++++-------------
 2 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index 8a016d44d4636..8d466486b3784 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -275,7 +275,12 @@ void LinkerDriver::addBuffer(std::unique_ptr<MemoryBuffer> mb,
 
       int memberIndex = 0;
       for (MemoryBufferRef m : getArchiveMembers(ctx, archive))
-        addArchiveBuffer(m, "<whole-archive>", filename, memberIndex++);
+        if (!archive->isThin())
+          addArchiveBuffer(m, "<whole-archive>", filename, memberIndex++);
+        else
+          // Pass empty string as archive name so that the original filename is
+          // used as the buffer identifier.
+          addArchiveBuffer(m, "<whole-archive>", "", /*OffsetInArchive=*/0);
       return;
     }
     addFile(make<ArchiveFile>(ctx, mbref));
diff --git a/lld/test/COFF/thin-archive.s b/lld/test/COFF/thin-archive.s
index 55d71ea635673..a7c6737443650 100644
--- a/lld/test/COFF/thin-archive.s
+++ b/lld/test/COFF/thin-archive.s
@@ -22,23 +22,34 @@
 # SYMTAB:        ?f@@YAHXZ in
 # NO-SYMTAB-NOT: ?f@@YAHXZ in
 
-# RUN: lld-link /entry:main %t.main.obj %t.lib /out:%t.exe 2>&1 | \
-# RUN:     FileCheck --allow-empty %s
-# RUN: lld-link /entry:main %t.main.obj %t_thin.lib /out:%t.exe 2>&1 | \
-# RUN:     FileCheck --allow-empty %s
-# RUN: lld-link /entry:main %t.main.obj /wholearchive:%t_thin.lib /out:%t.exe 2>&1 | \
-# RUN:     FileCheck --allow-empty %s
+# RUN: echo /entry:main %t.main.obj /out:%t.exe > %t.rsp
+
+# RUN: lld-link @%t.rsp %t.lib /verbose 2>&1 | \
+# RUN:     FileCheck %s --check-prefix=LOAD_NON_THIN
+# RUN: lld-link @%t.rsp %t_thin.lib /verbose 2>&1 | \
+# RUN:     FileCheck %s --check-prefix=LOAD_THIN_SYM
+# RUN: lld-link @%t.rsp /wholearchive:%t_thin.lib /verbose 2>&1 | \
+# RUN:     FileCheck %s --check-prefix=LOAD_THIN_WHOLE
+# RUN: lld-link @%t.rsp /wholearchive %t_thin.lib /verbose 2>&1 | \
+# RUN:     FileCheck %s --check-prefix=LOAD_THIN_WHOLE
+
+# LOAD_NON_THIN:   Loaded {{.*}}.lib({{.*}}.obj) for int __cdecl f(void)
+# LOAD_THIN_SYM:   Loaded {{.*}}.obj for int __cdecl f(void)
+# LOAD_THIN_WHOLE: Loaded {{.*}}.obj for <whole-archive>
 
 # RUN: rm %t.lib.obj
-# RUN: lld-link /entry:main %t.main.obj %t.lib /out:%t.exe 2>&1 | \
-# RUN:     FileCheck --allow-empty %s
-# RUN: env LLD_IN_TEST=1 not lld-link /entry:main %t.main.obj %t_thin.lib \
-# RUN:     /out:%t.exe 2>&1 | FileCheck --check-prefix=NOOBJ %s
-# RUN: env LLD_IN_TEST=1 not lld-link /entry:main %t.main.obj %t_thin.lib /out:%t.exe \
-# RUN:     /demangle:no 2>&1 | FileCheck --check-prefix=NOOBJNODEMANGLE %s
-
-# CHECK-NOT: error: could not get the buffer for the member defining
+# RUN: lld-link @%t.rsp %t.lib /out:%t.exe 2>&1 | \
+# RUN:     FileCheck --check-prefix=ERR --allow-empty  %s
+# RUN: env LLD_IN_TEST=1 not lld-link @%t.rsp %t_thin.lib 2>&1 | \
+# RUN:     FileCheck --check-prefix=NOOBJ %s
+# RUN: env LLD_IN_TEST=1 not lld-link @%t.rsp /wholearchive:%t_thin.lib 2>&1 | \
+# RUN:     FileCheck --check-prefix=NOOBJWHOLE %s
+# RUN: env LLD_IN_TEST=1 not lld-link @%t.rsp %t_thin.lib /demangle:no 2>&1 | \
+# RUN:     FileCheck --check-prefix=NOOBJNODEMANGLE %s
+
+# ERR-NOT: error: could not get the buffer for the member defining
 # NOOBJ: error: could not get the buffer for the member defining symbol int __cdecl f(void): {{.*}}.lib({{.*}}.lib.obj):
+# NOOBJWHOLE: error: {{.*}}.lib: could not get the buffer for a child of the archive: '{{.*}}.obj'
 # NOOBJNODEMANGLE: error: could not get the buffer for the member defining symbol ?f@@YAHXZ: {{.*}}.lib({{.*}}.lib.obj):
 
 	.text

>From 7df43648da2a1402bd60e281ef1959faaa8987a2 Mon Sep 17 00:00:00 2001
From: Dunbobbin <Ben.Dunbobbin at sony.com>
Date: Mon, 21 Jul 2025 14:30:55 +0100
Subject: [PATCH 2/5] Account for spaces in paths from lit substitutions

---
 lld/test/COFF/thin-archive.s | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lld/test/COFF/thin-archive.s b/lld/test/COFF/thin-archive.s
index a7c6737443650..1d5492c58bb04 100644
--- a/lld/test/COFF/thin-archive.s
+++ b/lld/test/COFF/thin-archive.s
@@ -22,7 +22,7 @@
 # SYMTAB:        ?f@@YAHXZ in
 # NO-SYMTAB-NOT: ?f@@YAHXZ in
 
-# RUN: echo /entry:main %t.main.obj /out:%t.exe > %t.rsp
+# RUN: echo "/entry:main \"%t.main.obj\" /out:\"%t.exe\"" > %t.rsp
 
 # RUN: lld-link @%t.rsp %t.lib /verbose 2>&1 | \
 # RUN:     FileCheck %s --check-prefix=LOAD_NON_THIN

>From 741543e8c3fc65f80f0deb37f073ef21c402dee9 Mon Sep 17 00:00:00 2001
From: Dunbobbin <Ben.Dunbobbin at sony.com>
Date: Mon, 21 Jul 2025 14:32:42 +0100
Subject: [PATCH 3/5] Remove duplicated command line argument in one of the
 test-cases.

---
 lld/test/COFF/thin-archive.s | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lld/test/COFF/thin-archive.s b/lld/test/COFF/thin-archive.s
index 1d5492c58bb04..f885460ecc6bc 100644
--- a/lld/test/COFF/thin-archive.s
+++ b/lld/test/COFF/thin-archive.s
@@ -38,7 +38,7 @@
 # LOAD_THIN_WHOLE: Loaded {{.*}}.obj for <whole-archive>
 
 # RUN: rm %t.lib.obj
-# RUN: lld-link @%t.rsp %t.lib /out:%t.exe 2>&1 | \
+# RUN: lld-link @%t.rsp %t.lib 2>&1 | \
 # RUN:     FileCheck --check-prefix=ERR --allow-empty  %s
 # RUN: env LLD_IN_TEST=1 not lld-link @%t.rsp %t_thin.lib 2>&1 | \
 # RUN:     FileCheck --check-prefix=NOOBJ %s

>From c2443311bc75848f8bfc80bfa47a2d53cc7a999c Mon Sep 17 00:00:00 2001
From: Dunbobbin <Ben.Dunbobbin at sony.com>
Date: Mon, 21 Jul 2025 14:34:18 +0100
Subject: [PATCH 4/5] Make FileCheck argument order consistent

---
 lld/test/COFF/thin-archive.s | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lld/test/COFF/thin-archive.s b/lld/test/COFF/thin-archive.s
index f885460ecc6bc..7fab10c2b57b4 100644
--- a/lld/test/COFF/thin-archive.s
+++ b/lld/test/COFF/thin-archive.s
@@ -39,13 +39,13 @@
 
 # RUN: rm %t.lib.obj
 # RUN: lld-link @%t.rsp %t.lib 2>&1 | \
-# RUN:     FileCheck --check-prefix=ERR --allow-empty  %s
+# RUN:     FileCheck %s --check-prefix=ERR --allow-empty
 # RUN: env LLD_IN_TEST=1 not lld-link @%t.rsp %t_thin.lib 2>&1 | \
-# RUN:     FileCheck --check-prefix=NOOBJ %s
+# RUN:     FileCheck %s --check-prefix=NOOBJ
 # RUN: env LLD_IN_TEST=1 not lld-link @%t.rsp /wholearchive:%t_thin.lib 2>&1 | \
-# RUN:     FileCheck --check-prefix=NOOBJWHOLE %s
+# RUN:     FileCheck %s --check-prefix=NOOBJWHOLE
 # RUN: env LLD_IN_TEST=1 not lld-link @%t.rsp %t_thin.lib /demangle:no 2>&1 | \
-# RUN:     FileCheck --check-prefix=NOOBJNODEMANGLE %s
+# RUN:     FileCheck %s --check-prefix=NOOBJNODEMANGLE
 
 # ERR-NOT: error: could not get the buffer for the member defining
 # NOOBJ: error: could not get the buffer for the member defining symbol int __cdecl f(void): {{.*}}.lib({{.*}}.lib.obj):

>From 8df4e6c3bf9722a56a89420ff038a48563f6c3a3 Mon Sep 17 00:00:00 2001
From: Dunbobbin <Ben.Dunbobbin at sony.com>
Date: Mon, 21 Jul 2025 15:29:04 +0100
Subject: [PATCH 5/5] Use common function to add thin archive members. Improve
 comment explaining parameter choice.

---
 lld/COFF/Driver.cpp | 25 ++++++++++++++++---------
 lld/COFF/Driver.h   |  1 +
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index 8d466486b3784..5c5e1ad630178 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -274,13 +274,13 @@ void LinkerDriver::addBuffer(std::unique_ptr<MemoryBuffer> mb,
       make<std::unique_ptr<Archive>>(std::move(file)); // take ownership
 
       int memberIndex = 0;
-      for (MemoryBufferRef m : getArchiveMembers(ctx, archive))
+      for (MemoryBufferRef m : getArchiveMembers(ctx, archive)) {
         if (!archive->isThin())
           addArchiveBuffer(m, "<whole-archive>", filename, memberIndex++);
         else
-          // Pass empty string as archive name so that the original filename is
-          // used as the buffer identifier.
-          addArchiveBuffer(m, "<whole-archive>", "", /*OffsetInArchive=*/0);
+          addThinArchiveBuffer(m, "<whole-archive>");
+      }
+
       return;
     }
     addFile(make<ArchiveFile>(ctx, mbref));
@@ -391,6 +391,16 @@ void LinkerDriver::addArchiveBuffer(MemoryBufferRef mb, StringRef symName,
   Log(ctx) << "Loaded " << obj << " for " << symName;
 }
 
+void LinkerDriver::addThinArchiveBuffer(MemoryBufferRef mb, StringRef symName) {
+  // Pass an empty string as the archive name and an offset of 0 so that
+  // the original filename is used as the buffer identifier. This
+  // ensures the naming of thin archive members is consistent with the
+  // non-`whole-archive` path, and is useful for DTLTO, where having the
+  // member identifier be the actual path on disk enables distribution
+  // of bitcode files during ThinLTO.
+  addArchiveBuffer(mb, symName, /*parentName=*/"", /*OffsetInArchive=*/0);
+}
+
 void LinkerDriver::enqueueArchiveMember(const Archive::Child &c,
                                         const Archive::Symbol &sym,
                                         StringRef parentName) {
@@ -427,11 +437,8 @@ void LinkerDriver::enqueueArchiveMember(const Archive::Child &c,
       reportBufferError(errorCodeToError(mbOrErr.second), childName);
     llvm::TimeTraceScope timeScope("Archive: ",
                                    mbOrErr.first->getBufferIdentifier());
-    // Pass empty string as archive name so that the original filename is
-    // used as the buffer identifier.
-    ctx.driver.addArchiveBuffer(takeBuffer(std::move(mbOrErr.first)),
-                                toCOFFString(ctx, sym), "",
-                                /*OffsetInArchive=*/0);
+    ctx.driver.addThinArchiveBuffer(takeBuffer(std::move(mbOrErr.first)),
+                                    toCOFFString(ctx, sym));
   });
 }
 
diff --git a/lld/COFF/Driver.h b/lld/COFF/Driver.h
index 14c97a98875bf..5a9bd5c6d9682 100644
--- a/lld/COFF/Driver.h
+++ b/lld/COFF/Driver.h
@@ -173,6 +173,7 @@ class LinkerDriver {
                  bool lazy);
   void addArchiveBuffer(MemoryBufferRef mbref, StringRef symName,
                         StringRef parentName, uint64_t offsetInArchive);
+  void addThinArchiveBuffer(MemoryBufferRef mbref, StringRef symName);
 
   void enqueueTask(std::function<void()> task);
   bool run();



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