[llvm-libc] Import setjmp from llvm-libc (emscripten-core#24765)

Defined a wasm-specific wasm/sigsetjmp.cpp that just fowards the call to
setjmp.

Defines in the musl header don't quite work with llvm-libc's setjmp.

Author: google-yfyang

system/lib/libc/musl/include/setjmp.h

@@ -26,7 +26,7 @@ typedef struct __jmp_buf_tag {
  || defined(_BSD_SOURCE)
 typedef jmp_buf sigjmp_buf;
 /* XXX EMSCRIPTEN: No signals support, alias sigsetjmp and siglongjmp to their non-signals counterparts. */
-#if __EMSCRIPTEN__
+#if __EMSCRIPTEN__ && !defined(LLVM_LIBC)
 #define sigsetjmp(buf, x) setjmp((buf))
 #define siglongjmp(buf, val) longjmp(buf, val)
 #else

system/lib/libc/musl/src/setjmp/longjmp.c

@@ -0,0 +1,3 @@
+#ifdef __EMSCRIPTEN__
+#define sigsetjmp(buf, x) setjmp((buf))
+#endif

system/lib/libc/musl/src/setjmp/setjmp.c

@@ -0,0 +1,3 @@
+#ifdef __EMSCRIPTEN__
+#define siglongjmp(buf, val) longjmp(buf, val)
+#endif

system/lib/llvm-libc/src/setjmp/longjmp.h

@@ -0,0 +1,34 @@
+//===-- Implementation header for longjmp -----------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_SETJMP_LONGJMP_H
+#define LLVM_LIBC_SRC_SETJMP_LONGJMP_H
+
+#include "hdr/types/jmp_buf.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/compiler.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+// TODO(https://github.com/llvm/llvm-project/issues/112427)
+// Some of the architecture-specific definitions are marked `naked`, which in
+// GCC implies `nothrow`.
+//
+// Right now, our aliases aren't marked `nothrow`, so we wind up in a situation
+// where clang will emit -Wmissing-exception-spec if we add `nothrow` here, but
+// GCC will emit -Wmissing-attributes here without `nothrow`. We need to update
+// LLVM_LIBC_FUNCTION to denote when a function throws or not.
+
+#ifdef LIBC_COMPILER_IS_GCC
+[[gnu::nothrow]]
+#endif
+void longjmp(jmp_buf buf, int val);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_SETJMP_LONGJMP_H

system/lib/llvm-libc/src/setjmp/setjmp_impl.h

@@ -0,0 +1,37 @@
+//===-- Implementation header for setjmp ------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_SETJMP_SETJMP_IMPL_H
+#define LLVM_LIBC_SRC_SETJMP_SETJMP_IMPL_H
+
+// This header has the _impl prefix in its name to avoid conflict with the
+// public header setjmp.h which is also included. here.
+#include "hdr/types/jmp_buf.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/compiler.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+// TODO(https://github.com/llvm/llvm-project/issues/112427)
+// Some of the architecture-specific definitions are marked `naked`, which in
+// GCC implies `nothrow`.
+//
+// Right now, our aliases aren't marked `nothrow`, so we wind up in a situation
+// where clang will emit -Wmissing-exception-spec if we add `nothrow` here, but
+// GCC will emit -Wmissing-attributes here without `nothrow`. We need to update
+// LLVM_LIBC_FUNCTION to denote when a function throws or not.
+
+#ifdef LIBC_COMPILER_IS_GCC
+[[gnu::nothrow]]
+#endif
+[[gnu::returns_twice]] int
+setjmp(jmp_buf buf);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_SETJMP_SETJMP_IMPL_H

system/lib/llvm-libc/src/setjmp/siglongjmp.cpp

@@ -0,0 +1,23 @@
+//===-- Implementation of siglongjmp --------------------------------------===//
+//
+// 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/siglongjmp.h"
+#include "src/__support/common.h"
+#include "src/setjmp/longjmp.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+// siglongjmp is the same as longjmp. The additional recovery work is done in
+// the epilogue of the sigsetjmp function.
+// TODO: move this inside the TU of longjmp and making it an alias after
+//       sigsetjmp is implemented for all architectures.
+LLVM_LIBC_FUNCTION(void, siglongjmp, (jmp_buf buf, int val)) {
+  return LIBC_NAMESPACE::longjmp(buf, val);
+}
+
+} // namespace LIBC_NAMESPACE_DECL

system/lib/llvm-libc/src/setjmp/siglongjmp.h

@@ -0,0 +1,25 @@
+//===-- Implementation header for siglongjmp --------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_SETJMP_SIGLONGJMP_H
+#define LLVM_LIBC_SRC_SETJMP_SIGLONGJMP_H
+
+#include "hdr/types/jmp_buf.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/compiler.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+#ifdef LIBC_COMPILER_IS_GCC
+[[gnu::nothrow]]
+#endif
+void siglongjmp(jmp_buf buf, int val);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_SETJMP_SIGLONGJMP_H

system/lib/llvm-libc/src/setjmp/sigsetjmp.h

@@ -0,0 +1,26 @@
+//===-- Implementation header for sigsetjmp ---------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_SETJMP_SIGSETJMP_H
+#define LLVM_LIBC_SRC_SETJMP_SIGSETJMP_H
+
+#include "hdr/types/jmp_buf.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/compiler.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+#ifdef LIBC_COMPILER_IS_GCC
+[[gnu::nothrow]]
+#endif
+[[gnu::returns_twice]] int
+sigsetjmp(sigjmp_buf buf, int savesigs);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_SETJMP_SIGSETJMP_H

system/lib/llvm-libc/src/setjmp/sigsetjmp_epilogue.h

@@ -0,0 +1,19 @@
+//===-- Implementation header for sigsetjmp epilogue ------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_SETJMP_SIGSETJMP_EPILOGUE_H
+#define LLVM_LIBC_SRC_SETJMP_SIGSETJMP_EPILOGUE_H
+
+#include "hdr/types/jmp_buf.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE_DECL {
+[[gnu::returns_twice]] int sigsetjmp_epilogue(jmp_buf buffer, int retval);
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_SETJMP_SIGSETJMP_EPILOGUE_H

system/lib/llvm-libc/src/setjmp/wasm/sigsetjmp.cpp

@@ -0,0 +1,14 @@
+#include "src/setjmp/sigsetjmp.h"
+#include "hdr/offsetof_macros.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+#if !defined(LIBC_TARGET_ARCH_IS_WASM)
+#error "Invalid file include"
+#endif
+
+namespace LIBC_NAMESPACE_DECL {
+[[gnu::returns_twice]] int sigsetjmp(jmp_buf sigjmp_buf, int savesigs) {
+    return setjmp(sigjmp_buf);
+}
+}