[libc-commits] [libc] [libc] at_quick_exit function implemented (PR #94317)
via libc-commits
libc-commits at lists.llvm.org
Tue Jun 4 13:08:56 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libc
Author: None (aaryanshukla)
<details>
<summary>Changes</summary>
- added at_quick_exit function
- used helper file exit_handler which reuses code from atexit
- atexit now calls helper functions from exit_handler
- test cases and dependencies are added
---
Full diff: https://github.com/llvm/llvm-project/pull/94317.diff
12 Files Affected:
- (modified) libc/config/linux/x86_64/entrypoints.txt (+3-1)
- (modified) libc/spec/stdc.td (+1)
- (modified) libc/src/stdlib/CMakeLists.txt (+38)
- (added) libc/src/stdlib/at_quick_exit.cpp (+37)
- (added) libc/src/stdlib/at_quick_exit.h (+17)
- (modified) libc/src/stdlib/atexit.cpp (+6-68)
- (modified) libc/src/stdlib/atexit.h (-5)
- (added) libc/src/stdlib/exit_handler.cpp (+46)
- (added) libc/src/stdlib/exit_handler.h (+52)
- (modified) libc/src/stdlib/quick_exit.cpp (+4-2)
- (modified) libc/test/src/stdlib/CMakeLists.txt (+17)
- (added) libc/test/src/stdlib/at_quick_exit_test.cpp (+90)
``````````diff
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 6506ea3108169..8b7bc874aacd9 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -173,7 +173,6 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.stdlib.atoll
libc.src.stdlib.bsearch
libc.src.stdlib.div
- libc.src.stdlib.quick_exit
libc.src.stdlib.labs
libc.src.stdlib.ldiv
libc.src.stdlib.llabs
@@ -751,6 +750,9 @@ if(LLVM_LIBC_FULL_BUILD)
libc.src.stdlib.abort
libc.src.stdlib.atexit
libc.src.stdlib.exit
+ libc.src.stdlib.quick_exit
+ libc.src.stdlib.at_quick_exit
+
libc.src.stdlib.getenv
# signal.h entrypoints
diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
index 2e64336ed4835..1e0f3ba18c106 100644
--- a/libc/spec/stdc.td
+++ b/libc/spec/stdc.td
@@ -1089,6 +1089,7 @@ def StdC : StandardSpec<"stdc"> {
FunctionSpec<"exit", RetValSpec<NoReturn>, [ArgSpec<IntType>]>,
FunctionSpec<"atexit", RetValSpec<IntType>, [ArgSpec<AtexitHandlerT>]>,
FunctionSpec<"quick_exit", RetValSpec<NoReturn>, [ArgSpec<IntType>]>,
+ FunctionSpec<"at_quick_exit", RetValSpec<IntType>, [ArgSpec<IntType>]>,
]
>;
diff --git a/libc/src/stdlib/CMakeLists.txt b/libc/src/stdlib/CMakeLists.txt
index e0bff5198b590..bf54324b111be 100644
--- a/libc/src/stdlib/CMakeLists.txt
+++ b/libc/src/stdlib/CMakeLists.txt
@@ -50,6 +50,7 @@ add_entrypoint_object(
quick_exit.h
DEPENDS
libc.src.__support.OSUtil.osutil
+ .exit_handler
)
add_entrypoint_object(
@@ -415,6 +416,23 @@ add_entrypoint_object(
libc.src.__support.OSUtil.osutil
)
+add_object_library(
+ exit_handler
+ SRCS
+ exit_handler.cpp
+ HDRS
+ exit_handler.h
+ CXX_STANDARD
+ 20 # For constinit
+ DEPENDS
+ libc.src.__support.CPP.mutex
+ libc.src.__support.CPP.new
+ libc.src.__support.OSUtil.osutil
+ libc.src.__support.blockstore
+ libc.src.__support.fixedvector
+ libc.src.__support.threads.mutex
+)
+
add_entrypoint_object(
atexit
SRCS
@@ -430,6 +448,24 @@ add_entrypoint_object(
libc.src.__support.blockstore
libc.src.__support.fixedvector
libc.src.__support.threads.mutex
+ .exit_handler
+ libc.include.stdlib
+)
+add_entrypoint_object(
+ at_quick_exit
+ SRCS
+ at_quick_exit.cpp
+ HDRS
+ at_quick_exit.h
+ DEPENDS
+ libc.src.__support.CPP.mutex
+ libc.src.__support.CPP.new
+ libc.src.__support.OSUtil.osutil
+ libc.src.__support.blockstore
+ libc.src.__support.fixedvector
+ libc.src.__support.threads.mutex
+ .exit_handler
+ libc.include.stdlib
)
add_entrypoint_object(
@@ -442,6 +478,8 @@ add_entrypoint_object(
._Exit
.atexit
libc.src.__support.OSUtil.osutil
+ .exit_handler
+ libc.include.stdlib
)
add_entrypoint_object(
diff --git a/libc/src/stdlib/at_quick_exit.cpp b/libc/src/stdlib/at_quick_exit.cpp
new file mode 100644
index 0000000000000..9d06dbd324a46
--- /dev/null
+++ b/libc/src/stdlib/at_quick_exit.cpp
@@ -0,0 +1,37 @@
+//===-- Implementation of at_quick_exit -----------------------------------===//
+//
+// 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/stdlib/at_quick_exit.h"
+#include "src/__support/CPP/mutex.h" // lock_guard
+#include "src/__support/blockstore.h"
+#include "src/__support/common.h"
+#include "src/__support/fixedvector.h"
+#include "src/__support/threads/mutex.h"
+#include "src/stdlib/exit_handler.h"
+namespace LIBC_NAMESPACE {
+
+extern "C" {
+
+int __cxa_at_quick_exit(AtExitCallback *callback, void *payload, void *) {
+ return add_atexit_unit(at_quick_exit_callbacks, {callback, payload});
+}
+
+void __cxa_finalize_quick_exit(void *dso) {
+ if (!dso)
+ call_exit_callbacks(at_quick_exit_callbacks);
+}
+
+} // extern "C"
+
+LLVM_LIBC_FUNCTION(int, at_quick_exit, (StdCAtExitCallback * callback)) {
+ return add_atexit_unit(
+ at_quick_exit_callbacks,
+ {&stdc_at_exit_func, reinterpret_cast<void *>(callback)});
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdlib/at_quick_exit.h b/libc/src/stdlib/at_quick_exit.h
new file mode 100644
index 0000000000000..d089e5462605b
--- /dev/null
+++ b/libc/src/stdlib/at_quick_exit.h
@@ -0,0 +1,17 @@
+//===-- Implementation header for at_quick_exit -----------------*- 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_STDLIB_AT_QUICK_EXIT_H
+#define LLVM_LIBC_SRC_STDLIB_AT_QUICK_EXIT_H
+
+namespace LIBC_NAMESPACE {
+
+int at_quick_exit(void (*function)());
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDLIB_AT_QUICK_EXIT_H
diff --git a/libc/src/stdlib/atexit.cpp b/libc/src/stdlib/atexit.cpp
index 9e37c4cf256c9..8f40291420cf5 100644
--- a/libc/src/stdlib/atexit.cpp
+++ b/libc/src/stdlib/atexit.cpp
@@ -12,91 +12,29 @@
#include "src/__support/common.h"
#include "src/__support/fixedvector.h"
#include "src/__support/threads/mutex.h"
+#include "src/stdlib/exit_handler.h"
namespace LIBC_NAMESPACE {
-namespace {
-
-Mutex handler_list_mtx(/*timed=*/false, /*recursive=*/false, /*robust=*/false,
- /*pshared=*/false);
-
-using AtExitCallback = void(void *);
-using StdCAtExitCallback = void(void);
-
-struct AtExitUnit {
- AtExitCallback *callback = nullptr;
- void *payload = nullptr;
- constexpr AtExitUnit() = default;
- constexpr AtExitUnit(AtExitCallback *c, void *p) : callback(c), payload(p) {}
-};
-
-#if defined(LIBC_TARGET_ARCH_IS_GPU)
-// The GPU build cannot handle the potentially recursive definitions required by
-// the BlockStore class. Additionally, the liklihood that someone exceeds this
-// while executing on the GPU is extremely small.
-// FIXME: It is not generally safe to use 'atexit' on the GPU because the
-// mutexes simply passthrough. We will need a lock free stack.
-using ExitCallbackList = FixedVector<AtExitUnit, 64>;
-#elif defined(LIBC_COPT_PUBLIC_PACKAGING)
-using ExitCallbackList = ReverseOrderBlockStore<AtExitUnit, 32>;
-#else
-// BlockStore uses dynamic memory allocation. To avoid dynamic memory
-// allocation in tests, we use a fixed size callback list when built for
-// tests.
-// If we use BlockStore, then we will have to pull in malloc etc into
-// the tests. While this is not bad, the problem we have currently is
-// that LLVM libc' allocator is SCUDO. So, we will end up pulling SCUDO's
-// deps also (some of which are not yet available in LLVM libc) into the
-// integration tests.
-using ExitCallbackList = FixedVector<AtExitUnit, CALLBACK_LIST_SIZE_FOR_TESTS>;
-#endif // LIBC_COPT_PUBLIC_PACKAGING
-
-constinit ExitCallbackList exit_callbacks;
-
-void stdc_at_exit_func(void *payload) {
- reinterpret_cast<StdCAtExitCallback *>(payload)();
-}
-
-void call_exit_callbacks() {
- handler_list_mtx.lock();
- while (!exit_callbacks.empty()) {
- AtExitUnit &unit = exit_callbacks.back();
- exit_callbacks.pop_back();
- handler_list_mtx.unlock();
- unit.callback(unit.payload);
- handler_list_mtx.lock();
- }
- ExitCallbackList::destroy(&exit_callbacks);
-}
-
-int add_atexit_unit(const AtExitUnit &unit) {
- cpp::lock_guard lock(handler_list_mtx);
- if (exit_callbacks.push_back(unit))
- return 0;
- return -1;
-}
-
-} // namespace
-
extern "C" {
-// TODO: Handle the last dso handle argument.
int __cxa_atexit(AtExitCallback *callback, void *payload, void *) {
- return add_atexit_unit({callback, payload});
+ return add_atexit_unit(atexit_callbacks, {callback, payload});
}
-// TODO: Handle the dso handle argument. call_exit_callbacks should only invoke
-// the callbacks from this DSO. Requires adding support for __dso_handle.
void __cxa_finalize(void *dso) {
if (!dso)
- call_exit_callbacks();
+ call_exit_callbacks(atexit_callbacks);
}
} // extern "C"
LLVM_LIBC_FUNCTION(int, atexit, (StdCAtExitCallback * callback)) {
return add_atexit_unit(
+ atexit_callbacks,
{&stdc_at_exit_func, reinterpret_cast<void *>(callback)});
}
} // namespace LIBC_NAMESPACE
+
+
diff --git a/libc/src/stdlib/atexit.h b/libc/src/stdlib/atexit.h
index 7cf9d7c92191d..f9323be257084 100644
--- a/libc/src/stdlib/atexit.h
+++ b/libc/src/stdlib/atexit.h
@@ -8,13 +8,8 @@
#ifndef LLVM_LIBC_SRC_STDLIB_ATEXIT_H
#define LLVM_LIBC_SRC_STDLIB_ATEXIT_H
-
-#include <stddef.h> // For size_t
-
namespace LIBC_NAMESPACE {
-constexpr size_t CALLBACK_LIST_SIZE_FOR_TESTS = 1024;
-
int atexit(void (*function)());
} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdlib/exit_handler.cpp b/libc/src/stdlib/exit_handler.cpp
new file mode 100644
index 0000000000000..a066ef729da95
--- /dev/null
+++ b/libc/src/stdlib/exit_handler.cpp
@@ -0,0 +1,46 @@
+//===--- Implementation of exit_handler------------------------------------===//
+//
+// 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/stdlib/exit_handler.h"
+#include "src/__support/CPP/mutex.h" // lock_guard
+#include "src/__support/blockstore.h"
+#include "src/__support/common.h"
+#include "src/__support/fixedvector.h"
+#include "src/__support/threads/mutex.h"
+
+namespace LIBC_NAMESPACE {
+
+constinit ExitCallbackList at_quick_exit_callbacks;
+constinit ExitCallbackList atexit_callbacks;
+
+Mutex handler_list_mtx(false, false, false, false);
+
+void stdc_at_exit_func(void *payload) {
+ reinterpret_cast<StdCAtExitCallback *>(payload)();
+}
+
+void call_exit_callbacks(ExitCallbackList &callbacks) {
+ handler_list_mtx.lock();
+ while (!callbacks.empty()) {
+ AtExitUnit &unit = callbacks.back();
+ callbacks.pop_back();
+ handler_list_mtx.unlock();
+ unit.callback(unit.payload);
+ handler_list_mtx.lock();
+ }
+ ExitCallbackList::destroy(&callbacks);
+}
+
+int add_atexit_unit(ExitCallbackList &callbacks, const AtExitUnit &unit) {
+ cpp::lock_guard lock(handler_list_mtx);
+ if (callbacks.push_back(unit))
+ return 0;
+ return -1;
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdlib/exit_handler.h b/libc/src/stdlib/exit_handler.h
new file mode 100644
index 0000000000000..473a4d32aa3ca
--- /dev/null
+++ b/libc/src/stdlib/exit_handler.h
@@ -0,0 +1,52 @@
+//===-- Implementation header for exit_handler ------------------*- 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_STDLIB_EXIT_HANDLER_H
+#define LLVM_LIBC_SRC_STDLIB_EXIT_HANDLER_H
+
+#include "src/__support/CPP/mutex.h" // lock_guard
+#include "src/__support/blockstore.h"
+#include "src/__support/common.h"
+#include "src/__support/fixedvector.h"
+#include "src/__support/threads/mutex.h"
+
+namespace LIBC_NAMESPACE {
+
+using AtExitCallback = void(void *);
+using StdCAtExitCallback = void(void);
+constexpr size_t CALLBACK_LIST_SIZE_FOR_TESTS = 1024;
+
+struct AtExitUnit {
+ AtExitCallback *callback = nullptr;
+ void *payload = nullptr;
+ constexpr AtExitUnit() = default;
+ constexpr AtExitUnit(AtExitCallback *c, void *p) : callback(c), payload(p) {}
+};
+
+#if defined(LIBC_TARGET_ARCH_IS_GPU)
+using ExitCallbackList = FixedVector<AtExitUnit, 64>;
+#elif defined(LIBC_COPT_PUBLIC_PACKAGING)
+using ExitCallbackList = ReverseOrderBlockStore<AtExitUnit, 32>;
+#else
+using ExitCallbackList = FixedVector<AtExitUnit, CALLBACK_LIST_SIZE_FOR_TESTS>;
+#endif
+
+extern ExitCallbackList atexit_callbacks;
+extern ExitCallbackList at_quick_exit_callbacks;
+
+extern Mutex handler_list_mtx;
+
+void stdc_at_exit_func(void *payload);
+
+void call_exit_callbacks(ExitCallbackList &callbacks);
+
+int add_atexit_unit(ExitCallbackList &callbacks, const AtExitUnit &unit);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDLIB_EXIT_HANDLER_H
diff --git a/libc/src/stdlib/quick_exit.cpp b/libc/src/stdlib/quick_exit.cpp
index cf7f07bf2439a..38f0a3db3e2cf 100644
--- a/libc/src/stdlib/quick_exit.cpp
+++ b/libc/src/stdlib/quick_exit.cpp
@@ -9,13 +9,15 @@
#include "src/stdlib/quick_exit.h"
#include "src/__support/OSUtil/exit.h"
#include "src/__support/common.h"
+#include "src/stdlib/exit_handler.h"
// extern "C" void __cxa_finalize(void *);
-
namespace LIBC_NAMESPACE {
+extern ExitCallbackList at_quick_exit_callbacks;
+
[[noreturn]] LLVM_LIBC_FUNCTION(void, quick_exit, (int status)) {
- // __cxa_finalize(nullptr);
+ call_exit_callbacks(at_quick_exit_callbacks);
internal::exit(status);
}
diff --git a/libc/test/src/stdlib/CMakeLists.txt b/libc/test/src/stdlib/CMakeLists.txt
index 6a7faedece380..76c325db55109 100644
--- a/libc/test/src/stdlib/CMakeLists.txt
+++ b/libc/test/src/stdlib/CMakeLists.txt
@@ -357,6 +357,23 @@ if(LLVM_LIBC_FULL_BUILD)
libc.src.__support.CPP.utility
)
+ add_libc_test(
+ at_quick_exit_test
+ # The EXPECT_EXITS test is only availible for unit tests.
+ UNIT_TEST_ONLY
+ SUITE
+ libc-stdlib-tests
+ SRCS
+ at_quick_exit_test.cpp
+ DEPENDS
+ libc.include.stdlib
+ libc.src.stdlib._Exit
+ libc.src.stdlib.quick_exit
+ libc.src.stdlib.at_quick_exit
+ libc.src.__support.CPP.array
+ libc.src.__support.CPP.utility
+ )
+
add_libc_test(
abort_test
# The EXPECT_DEATH test is only availible for unit tests.
diff --git a/libc/test/src/stdlib/at_quick_exit_test.cpp b/libc/test/src/stdlib/at_quick_exit_test.cpp
new file mode 100644
index 0000000000000..2c94b59d47bef
--- /dev/null
+++ b/libc/test/src/stdlib/at_quick_exit_test.cpp
@@ -0,0 +1,90 @@
+//===-- Unittests for at_quick_exit ---------------------------------------===//
+//
+// 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/__support/CPP/array.h"
+#include "src/__support/CPP/utility.h"
+#include "src/stdlib/at_quick_exit.h"
+#include "src/stdlib/quick_exit.h"
+#include "test/UnitTest/Test.h"
+
+static int a;
+TEST(LlvmLibcAtQuickExit, Basic) {
+ // In case tests ever run multiple times.
+ a = 0;
+
+ auto test = [] {
+ int status = LIBC_NAMESPACE::at_quick_exit(+[] {
+ if (a != 1)
+ __builtin_trap();
+ });
+ status |= LIBC_NAMESPACE::at_quick_exit(+[] { a++; });
+ if (status)
+ __builtin_trap();
+
+ LIBC_NAMESPACE::quick_exit(0);
+ };
+ EXPECT_EXITS(test, 0);
+}
+
+TEST(LlvmLibcAtQuickExit, AtQuickExitCallsSysExit) {
+ auto test = [] {
+ LIBC_NAMESPACE::at_quick_exit(+[] { _Exit(1); });
+ LIBC_NAMESPACE::quick_exit(0);
+ };
+ EXPECT_EXITS(test, 1);
+}
+
+static int size;
+static LIBC_NAMESPACE::cpp::array<int, 256> arr;
+
+template <int... Ts>
+void register_at_quick_exit_handlers(
+ LIBC_NAMESPACE::cpp::integer_sequence<int, Ts...>) {
+ (LIBC_NAMESPACE::at_quick_exit(+[] { arr[size++] = Ts; }), ...);
+}
+
+template <int count> constexpr auto get_test() {
+ return [] {
+ LIBC_NAMESPACE::at_quick_exit(+[] {
+ if (size != count)
+ __builtin_trap();
+ for (int i = 0; i < count; i++)
+ if (arr[i] != count - 1 - i)
+ __builtin_trap();
+ });
+ register_at_quick_exit_handlers(
+ LIBC_NAMESPACE::cpp::make_integer_sequence<int, count>{});
+ LIBC_NAMESPACE::quick_exit(0);
+ };
+}
+
+TEST(LlvmLibcAtQuickExit, ReverseOrder) {
+ // In case tests ever run multiple times.
+ size = 0;
+
+ auto test = get_test<32>();
+ EXPECT_EXITS(test, 0);
+}
+
+TEST(LlvmLibcAtQuickExit, Many) {
+ // In case tests ever run multiple times.
+ size = 0;
+
+ auto test = get_test<256>();
+ EXPECT_EXITS(test, 0);
+}
+
+TEST(LlvmLibcAtQuickExit, HandlerCallsAtQuickExit) {
+ auto test = [] {
+ LIBC_NAMESPACE::at_quick_exit(+[] {
+ LIBC_NAMESPACE::at_quick_exit(+[] { LIBC_NAMESPACE::quick_exit(1); });
+ });
+ LIBC_NAMESPACE::quick_exit(0);
+ };
+ EXPECT_EXITS(test, 1);
+}
\ No newline at end of file
``````````
</details>
https://github.com/llvm/llvm-project/pull/94317
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