release/21.x: [LLD][COFF] Make /wholearchive thin-archive member identifiers consistent (#145487) #150168

llvmbot · 2025-07-23T05:38:16Z

Backport 9f733f4

Requested by: @bd1976bris

llvmbot · 2025-07-23T05:38:23Z

@aganea What do you think about merging this PR to the release branch?

llvmbot · 2025-07-23T05:38:48Z

@llvm/pr-subscribers-lld-coff

@llvm/pr-subscribers-platform-windows

Author: None (llvmbot)

Changes

Backport 9f733f4

Requested by: @bd1976bris

Full diff: https://github.com/llvm/llvm-project/pull/150168.diff

3 Files Affected:

(modified) lld/COFF/Driver.cpp (+17-7)
(modified) lld/COFF/Driver.h (+1)
(modified) lld/test/COFF/thin-archive.s (+25-14)

diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index 0f649ff1cf4f8..4a7ea6fff217b 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -274,8 +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))
-        addArchiveBuffer(m, "<whole-archive>", filename, memberIndex++);
+      for (MemoryBufferRef m : getArchiveMembers(ctx, archive)) {
+        if (!archive->isThin())
+          addArchiveBuffer(m, "<whole-archive>", filename, memberIndex++);
+        else
+          addThinArchiveBuffer(m, "<whole-archive>");
+      }
+
       return;
     }
     addFile(make<ArchiveFile>(ctx, mbref));
@@ -386,6 +391,14 @@ 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 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) {
@@ -422,11 +435,8 @@ 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();
diff --git a/lld/test/COFF/thin-archive.s b/lld/test/COFF/thin-archive.s
index 55d71ea635673..7fab10c2b57b4 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 2>&1 | \
+# 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 %s --check-prefix=NOOBJ
+# RUN: env LLD_IN_TEST=1 not lld-link @%t.rsp /wholearchive:%t_thin.lib 2>&1 | \
+# 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 %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):
+# 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

llvmbot · 2025-07-23T05:38:48Z

@llvm/pr-subscribers-lld

Author: None (llvmbot)

Changes

Backport 9f733f4

Requested by: @bd1976bris

Full diff: https://github.com/llvm/llvm-project/pull/150168.diff

3 Files Affected:

(modified) lld/COFF/Driver.cpp (+17-7)
(modified) lld/COFF/Driver.h (+1)
(modified) lld/test/COFF/thin-archive.s (+25-14)

diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index 0f649ff1cf4f8..4a7ea6fff217b 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -274,8 +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))
-        addArchiveBuffer(m, "<whole-archive>", filename, memberIndex++);
+      for (MemoryBufferRef m : getArchiveMembers(ctx, archive)) {
+        if (!archive->isThin())
+          addArchiveBuffer(m, "<whole-archive>", filename, memberIndex++);
+        else
+          addThinArchiveBuffer(m, "<whole-archive>");
+      }
+
       return;
     }
     addFile(make<ArchiveFile>(ctx, mbref));
@@ -386,6 +391,14 @@ 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 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) {
@@ -422,11 +435,8 @@ 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();
diff --git a/lld/test/COFF/thin-archive.s b/lld/test/COFF/thin-archive.s
index 55d71ea635673..7fab10c2b57b4 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 2>&1 | \
+# 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 %s --check-prefix=NOOBJ
+# RUN: env LLD_IN_TEST=1 not lld-link @%t.rsp /wholearchive:%t_thin.lib 2>&1 | \
+# 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 %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):
+# 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

…tent (llvm#145487) 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 (llvm#126654), where having the member identifier be the path on disk allows distribution of bitcode members during ThinLTO. (cherry picked from commit 9f733f4)

github-actions · 2025-07-24T09:59:51Z

@bd1976bris (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR.

llvmbot added this to the LLVM 21.x Release milestone Jul 23, 2025

github-project-automation bot added this to LLVM Release Status Jul 23, 2025

github-project-automation bot moved this to Needs Triage in LLVM Release Status Jul 23, 2025

llvmbot requested a review from aganea July 23, 2025 05:38

llvmbot added lld lld:COFF platform:windows labels Jul 23, 2025

llvmbot mentioned this pull request Jul 23, 2025

[LLD][COFF] Make /wholearchive thin-archive member identifiers consistent #145487

Merged

tru moved this from Needs Triage to Needs Merge in LLVM Release Status Jul 24, 2025

tru approved these changes Jul 24, 2025

View reviewed changes

tru force-pushed the issue145487 branch from f4ed0b8 to 64a274f Compare July 24, 2025 09:59

tru merged commit 64a274f into llvm:release/21.x Jul 24, 2025

github-project-automation bot moved this from Needs Merge to Done in LLVM Release Status Jul 24, 2025

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release/21.x: [LLD][COFF] Make /wholearchive thin-archive member identifiers consistent (#145487) #150168

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