[llvm-branch-commits] [compiler-rt] 8b49023 - [Compiler-rt][test] Fix circular link dependency between builtins and libc (#199482)

[via llvm-branch-commits]

Author: Garvit Gupta
Date: 2026-06-09T14:12:27+05:30
New Revision: 8b4902300521d4a0980d9d35210c02b405f0df86

URL: https://github.com/llvm/llvm-project/commit/8b4902300521d4a0980d9d35210c02b405f0df86
DIFF: https://github.com/llvm/llvm-project/commit/8b4902300521d4a0980d9d35210c02b405f0df86.diff

LOG: [Compiler-rt][test] Fix circular link dependency between builtins and libc (#199482)

Currently, the link order is `libclang_rt.builtins.a -lc -lm`. Builtins
are scanned first after which symbols like `abort` are unresolved
references that are resolved through libc.a. However, resolving the
references to these symbols further lead to undefined references to
`_aeabi_uldivmod` etc. that can only resolved through builtins.
Reversing the order also wont fix the issue because `libc.a` introduces
`__aeabi_uldivmod` which is resolved by builtins but it introduces
`abort` which can only be resolved libc.a.

This patch fixes this by wrapping the archives in a linker group
(--start-group/--end-group), which instructs the linker to rescan all
archives in the group until no new symbols can be resolved.

This error is exposed only when bfd like linkers are used.

Added: 
    

Modified: 
    compiler-rt/test/builtins/Unit/lit.cfg.py

Removed: 
    


################################################################################
diff  --git a/compiler-rt/test/builtins/Unit/lit.cfg.py b/compiler-rt/test/builtins/Unit/lit.cfg.py
index 8d602d1c417fa..2bb72630a41e9 100644
--- a/compiler-rt/test/builtins/Unit/lit.cfg.py
+++ b/compiler-rt/test/builtins/Unit/lit.cfg.py
@@ -107,7 +107,9 @@ def get_libgcc_file_name():
     if config.target_os == "Haiku":
         config.substitutions.append(("%librt ", base_lib + " -lroot "))
     else:
-        config.substitutions.append(("%librt ", base_lib + " -lc -lm "))
+        config.substitutions.append(
+            ("%librt ", "-lm -Wl,--start-group " + base_lib + " -lc -Wl,--end-group ")
+        )
 
 builtins_test_crt = get_required_attr(config, "builtins_test_crt")
 if builtins_test_crt: