[libc] build fix for sigsetjmp

[SchrodingerZhu]

This PR fixes the build failure due to the sigsetjmp implementation.

1. Use a most relaxed input constraint to fix clang build.
2. Avoid create alias target if os directory for sigsetjmp_epilogue does not exist.

[llvmbot]

@llvm/pr-subscribers-libc

Author: Schrodinger ZHU Yifan (SchrodingerZhu)

Changes

This PR fixes the build failure due to the sigsetjmp implementation.

1. Use a most relaxed input constraint to fix clang build.
2. Avoid create alias target if os directory for sigsetjmp_epilogue does not exist.

---

Full diff: https://github.com/llvm/llvm-project/pull/137047.diff

2 Files Affected:

• (modified) libc/src/setjmp/CMakeLists.txt (+6-7)
• (modified) libc/src/setjmp/x86_64/sigsetjmp.cpp (+4-4)

diff --git a/libc/src/setjmp/CMakeLists.txt b/libc/src/setjmp/CMakeLists.txt
index 3a3628bafe7ca..2591319f15240 100644
--- a/libc/src/setjmp/CMakeLists.txt
+++ b/libc/src/setjmp/CMakeLists.txt
@@ -1,14 +1,13 @@
 if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
   add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
+  add_object_library(
+    sigsetjmp_epilogue
+    ALIAS
+    DEPENDS
+      .${LIBC_TARGET_OS}.sigsetjmp_epilogue
+  )
 endif()
 
-add_object_library(
-  sigsetjmp_epilogue
-  ALIAS
-  DEPENDS
-    .${LIBC_TARGET_OS}.sigsetjmp_epilogue
-)
-
 if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_ARCHITECTURE})
   add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_ARCHITECTURE})
 endif()
diff --git a/libc/src/setjmp/x86_64/sigsetjmp.cpp b/libc/src/setjmp/x86_64/sigsetjmp.cpp
index dc41a71321322..4c97a01822679 100644
--- a/libc/src/setjmp/x86_64/sigsetjmp.cpp
+++ b/libc/src/setjmp/x86_64/sigsetjmp.cpp
@@ -37,8 +37,8 @@ LLVM_LIBC_FUNCTION(int, sigsetjmp, (sigjmp_buf buf)) {
       
 .Lnosave:
       jmp %P[setjmp])" ::[retaddr] "i"(offsetof(__jmp_buf, sig_retaddr)),
-      [extra] "i"(offsetof(__jmp_buf, sig_extra)), [setjmp] "i"(setjmp),
-      [epilogue] "i"(sigsetjmp_epilogue)
+      [extra] "i"(offsetof(__jmp_buf, sig_extra)), [setjmp] "X"(setjmp),
+      [epilogue] "X"(sigsetjmp_epilogue)
       : "eax", "ebx", "ecx");
 }
 #endif
@@ -60,8 +60,8 @@ LLVM_LIBC_FUNCTION(int, sigsetjmp, (sigjmp_buf, int)) {
       
 .Lnosave:
       jmp %P[setjmp])" ::[retaddr] "i"(offsetof(__jmp_buf, sig_retaddr)),
-      [extra] "i"(offsetof(__jmp_buf, sig_extra)), [setjmp] "i"(setjmp),
-      [epilogue] "i"(sigsetjmp_epilogue)
+      [extra] "i"(offsetof(__jmp_buf, sig_extra)), [setjmp] "X"(setjmp),
+      [epilogue] "X"(sigsetjmp_epilogue)
       : "rax", "rbx");
 }
 

[Copilot]

Pull Request Overview

This PR fixes a build failure in the sigsetjmp implementation by adjusting inline assembly constraints and avoiding alias target creation when the OS directory for sigsetjmp_epilogue is missing.

• Update inline assembly constraints from "i" to "X" for both sigsetjmp functions
• Bypass alias target creation when the required OS directory is absent

Files not reviewed (1)

• libc/src/setjmp/CMakeLists.txt: Language not supported