[llvm] b3e7900 - [llvm-readobj] Exclude Mach-O dylib IDs from needed libraries (#221618)

[via llvm-commits]

Author: Tianyi Chen
Date: 2026-09-10T11:29:56+01:00
New Revision: b3e7900e74098de130402d0a3ea857e77d817540

URL: https://github.com/llvm/llvm-project/commit/b3e7900e74098de130402d0a3ea857e77d817540
DIFF: https://github.com/llvm/llvm-project/commit/b3e7900e74098de130402d0a3ea857e77d817540.diff

LOG: [llvm-readobj] Exclude Mach-O dylib IDs from needed libraries (#221618)

For Mach-O files, `--needed-libs` includes `LC_ID_DYLIB`, causing a
dynamic
library to list its own install name as a dependency.

Exclude this command while retaining the actual dependency load
commands.

Fixes #39505.

Assisted-by: OpenAI Codex (implementation, tests, and initial
description).

Added: 
    

Modified: 
    llvm/test/tools/llvm-readobj/MachO/needed-libs.test
    llvm/tools/llvm-readobj/MachODumper.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/test/tools/llvm-readobj/MachO/needed-libs.test b/llvm/test/tools/llvm-readobj/MachO/needed-libs.test
index e97e490dbb075..75de64b338da1 100644
--- a/llvm/test/tools/llvm-readobj/MachO/needed-libs.test
+++ b/llvm/test/tools/llvm-readobj/MachO/needed-libs.test
@@ -1,8 +1,13 @@
+## LC_ID_DYLIB names the library itself, not a dependency.
 # RUN: yaml2obj %s -o %t.o
 # RUN: llvm-readobj --needed-libs %t.o | FileCheck %s
 
 # CHECK:      NeededLibraries [
+# CHECK-NEXT:   /usr/lib/libLazy.dylib
+# CHECK-NEXT:   /usr/lib/libReexport.dylib
 # CHECK-NEXT:   /usr/lib/libSystem.B.dylib
+# CHECK-NEXT:   /usr/lib/libUpward.dylib
+# CHECK-NEXT:   /usr/lib/libWeak.dylib
 # CHECK-NEXT: ]
 
 !mach-o
@@ -10,12 +15,20 @@ FileHeader:
   magic:           0xFEEDFACF
   cputype:         0x01000007
   cpusubtype:      0x00000003
-  filetype:        0x00000001
-  ncmds:           1
-  sizeofcmds:      56
+  filetype:        0x00000006
+  ncmds:           6
+  sizeofcmds:      336
   flags:           0x00002000
   reserved:        0x00000000
 LoadCommands:
+  - cmd:             LC_ID_DYLIB
+    cmdsize:         56
+    dylib:
+      name:            24
+      timestamp:       2
+      current_version: 81985536
+      compatibility_version: 65536
+    Content:         /usr/lib/libSelf.dylib
   - cmd:             LC_LOAD_DYLIB
     cmdsize:         56
     dylib:
@@ -24,3 +37,35 @@ LoadCommands:
       current_version: 81985536
       compatibility_version: 65536
     Content:         /usr/lib/libSystem.B.dylib
+  - cmd:             LC_LOAD_WEAK_DYLIB
+    cmdsize:         56
+    dylib:
+      name:            24
+      timestamp:       2
+      current_version: 81985536
+      compatibility_version: 65536
+    Content:         /usr/lib/libWeak.dylib
+  - cmd:             LC_REEXPORT_DYLIB
+    cmdsize:         56
+    dylib:
+      name:            24
+      timestamp:       2
+      current_version: 81985536
+      compatibility_version: 65536
+    Content:         /usr/lib/libReexport.dylib
+  - cmd:             LC_LAZY_LOAD_DYLIB
+    cmdsize:         56
+    dylib:
+      name:            24
+      timestamp:       2
+      current_version: 81985536
+      compatibility_version: 65536
+    Content:         /usr/lib/libLazy.dylib
+  - cmd:             LC_LOAD_UPWARD_DYLIB
+    cmdsize:         56
+    dylib:
+      name:            24
+      timestamp:       2
+      current_version: 81985536
+      compatibility_version: 65536
+    Content:         /usr/lib/libUpward.dylib

diff  --git a/llvm/tools/llvm-readobj/MachODumper.cpp b/llvm/tools/llvm-readobj/MachODumper.cpp
index 8fc92850606af..5a0bcf040b304 100644
--- a/llvm/tools/llvm-readobj/MachODumper.cpp
+++ b/llvm/tools/llvm-readobj/MachODumper.cpp
@@ -826,7 +826,6 @@ void MachODumper::printNeededLibraries() {
 
   for (const auto &Command : Obj->load_commands()) {
     if (Command.C.cmd == MachO::LC_LOAD_DYLIB ||
-        Command.C.cmd == MachO::LC_ID_DYLIB ||
         Command.C.cmd == MachO::LC_LOAD_WEAK_DYLIB ||
         Command.C.cmd == MachO::LC_REEXPORT_DYLIB ||
         Command.C.cmd == MachO::LC_LAZY_LOAD_DYLIB ||