[libc-commits] [libc] [libc] implement aarch64 sigsetjmp (PR #136706)

[Schrodinger ZHU Yifan via libc-commits]

https://github.com/SchrodingerZhu updated https://github.com/llvm/llvm-project/pull/136706

>From a325f7fece19773695b79e783e76c39d68f58feb Mon Sep 17 00:00:00 2001
From: Schrodinger ZHU Yifan <yifanzhu at rochester.edu>
Date: Tue, 22 Apr 2025 10:46:43 -0400
Subject: [PATCH] [libc][aarch64] implement sigsetjmp

---
 libc/config/linux/aarch64/entrypoints.txt |  2 ++
 libc/include/llvm-libc-types/jmp_buf.h    |  4 +--
 libc/src/setjmp/aarch64/CMakeLists.txt    | 14 +++++++++
 libc/src/setjmp/aarch64/sigsetjmp.cpp     | 36 +++++++++++++++++++++++
 4 files changed, 54 insertions(+), 2 deletions(-)
 create mode 100644 libc/src/setjmp/aarch64/sigsetjmp.cpp

diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index be5f5a66016b5..57058633ae50a 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -932,6 +932,8 @@ if(LLVM_LIBC_FULL_BUILD)
     # setjmp.h entrypoints
     libc.src.setjmp.longjmp
     libc.src.setjmp.setjmp
+    libc.src.setjmp.siglongjmp
+    libc.src.setjmp.sigsetjmp
 
     # stdio.h entrypoints
     libc.src.stdio.clearerr
diff --git a/libc/include/llvm-libc-types/jmp_buf.h b/libc/include/llvm-libc-types/jmp_buf.h
index 1e7791610857d..0376332f2a0dc 100644
--- a/libc/include/llvm-libc-types/jmp_buf.h
+++ b/libc/include/llvm-libc-types/jmp_buf.h
@@ -54,7 +54,7 @@ typedef struct {
 #endif
   // TODO: implement sigjmp_buf related functions for other architectures
   // Issue: https://github.com/llvm/llvm-project/issues/136358
-#if defined(__i386__) || defined(__x86_64__)
+#if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__)
   // return address
   void *sig_retaddr;
   // extra register buffer to avoid indefinite stack growth in sigsetjmp
@@ -66,7 +66,7 @@ typedef struct {
 
 typedef __jmp_buf jmp_buf[1];
 
-#if defined(__i386__) || defined(__x86_64__)
+#if defined(__i386__) || defined(__x86_64__) || defined(__aarch64__)
 typedef __jmp_buf sigjmp_buf[1];
 #endif
 #endif // LLVM_LIBC_TYPES_JMP_BUF_H
diff --git a/libc/src/setjmp/aarch64/CMakeLists.txt b/libc/src/setjmp/aarch64/CMakeLists.txt
index e0e7702c7c4b6..1078af8ce04f3 100644
--- a/libc/src/setjmp/aarch64/CMakeLists.txt
+++ b/libc/src/setjmp/aarch64/CMakeLists.txt
@@ -26,3 +26,17 @@ add_entrypoint_object(
     libc.hdr.types.jmp_buf
   ${setjmp_config_options}
 )
+
+add_entrypoint_object(
+  sigsetjmp
+  SRCS
+    sigsetjmp.cpp
+  HDRS
+    ../sigsetjmp.h
+  DEPENDS
+    libc.hdr.types.jmp_buf
+    libc.hdr.types.sigset_t
+    libc.hdr.offsetof_macros
+    libc.src.setjmp.sigsetjmp_epilogue
+    libc.src.setjmp.setjmp
+)
diff --git a/libc/src/setjmp/aarch64/sigsetjmp.cpp b/libc/src/setjmp/aarch64/sigsetjmp.cpp
new file mode 100644
index 0000000000000..734591b2aca4c
--- /dev/null
+++ b/libc/src/setjmp/aarch64/sigsetjmp.cpp
@@ -0,0 +1,36 @@
+//===-- Implementation of sigsetjmp ---------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/setjmp/sigsetjmp.h"
+#include "hdr/offsetof_macros.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/setjmp/setjmp_impl.h"
+#include "src/setjmp/sigsetjmp_epilogue.h"
+
+namespace LIBC_NAMESPACE_DECL {
+[[gnu::naked]]
+LLVM_LIBC_FUNCTION(int, sigsetjmp, (sigjmp_buf, int)) {
+  asm(R"(
+      cbz w1, %c[setjmp]
+
+      str x30, [x0, %c[retaddr]]
+      str x19, [x0, %c[extra]]
+      mov x19, x0
+      bl %c[setjmp]
+
+      mov w1, w0
+      mov x0, x19
+      ldr x30, [x0, %c[retaddr]]
+      ldr x19, [x0, %c[extra]]
+      b %c[epilogue])" ::[retaddr] "i"(offsetof(__jmp_buf, sig_retaddr)),
+      [extra] "i"(offsetof(__jmp_buf, sig_extra)), [setjmp] "i"(setjmp),
+      [epilogue] "i"(sigsetjmp_epilogue)
+      : "x0", "x1", "x19", "x30");
+}
+} // namespace LIBC_NAMESPACE_DECL