[libc-commits] [libc] 203aff2 - [LIBC] Implement `sched_yield()`
Noah Goldstein via libc-commits
libc-commits at lists.llvm.org
Wed Apr 12 17:04:57 PDT 2023
Author: Noah Goldstein
Date: 2023-04-12T19:04:37-05:00
New Revision: 203aff2df368f63532c0db4c5ab2879438654814
URL: https://github.com/llvm/llvm-project/commit/203aff2df368f63532c0db4c5ab2879438654814
DIFF: https://github.com/llvm/llvm-project/commit/203aff2df368f63532c0db4c5ab2879438654814.diff
LOG: [LIBC] Implement `sched_yield()`
Implements: https://linux.die.net/man/2/sched_yield
Possibly we don't need the return value check / errno as according to
both the manpage (and current linux source) `sched_yield` cannot fail.
Reviewed By: sivachandra, michaelrj
Differential Revision: https://reviews.llvm.org/D147985
Added:
libc/src/sched/linux/sched_yield.cpp
libc/src/sched/sched_yield.h
libc/test/src/sched/yield_test.cpp
Modified:
libc/config/linux/aarch64/entrypoints.txt
libc/config/linux/riscv64/entrypoints.txt
libc/config/linux/x86_64/entrypoints.txt
libc/spec/gnu_ext.td
libc/spec/posix.td
libc/src/sched/CMakeLists.txt
libc/src/sched/linux/CMakeLists.txt
libc/test/src/sched/CMakeLists.txt
Removed:
################################################################################
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 4ebe5fd48657b..166114f08b76d 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -28,6 +28,7 @@ set(TARGET_LIBC_ENTRYPOINTS
# sched.h entrypoints
libc.src.sched.sched_getaffinity
libc.src.sched.sched_setaffinity
+ libc.src.sched.sched_yield
# string.h entrypoints
libc.src.string.bcmp
diff --git a/libc/config/linux/riscv64/entrypoints.txt b/libc/config/linux/riscv64/entrypoints.txt
index 5902b50defe37..47827bd4efba2 100644
--- a/libc/config/linux/riscv64/entrypoints.txt
+++ b/libc/config/linux/riscv64/entrypoints.txt
@@ -28,6 +28,7 @@ set(TARGET_LIBC_ENTRYPOINTS
# sched.h entrypoints
libc.src.sched.sched_getaffinity
libc.src.sched.sched_setaffinity
+ libc.src.sched.sched_yield
# string.h entrypoints
libc.src.string.bcmp
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index deff7dba9ec57..b4e6d51322e57 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -28,6 +28,7 @@ set(TARGET_LIBC_ENTRYPOINTS
# sched.h entrypoints
libc.src.sched.sched_getaffinity
libc.src.sched.sched_setaffinity
+ libc.src.sched.sched_yield
# string.h entrypoints
libc.src.string.bcmp
diff --git a/libc/spec/gnu_ext.td b/libc/spec/gnu_ext.td
index 0c45d5cafbbf7..d02733511464e 100644
--- a/libc/spec/gnu_ext.td
+++ b/libc/spec/gnu_ext.td
@@ -32,7 +32,7 @@ def GnuExtensions : StandardSpec<"GNUExtensions"> {
FunctionSpec<"exp10f", RetValSpec<FloatType>, [ArgSpec<FloatType>]>,
]
>;
-
+
HeaderSpec Sched = HeaderSpec<
"sched.h",
[], // Macros
@@ -51,7 +51,7 @@ def GnuExtensions : StandardSpec<"GNUExtensions"> {
>,
]
>;
-
+
HeaderSpec String = HeaderSpec<
"string.h",
[], // Macros
diff --git a/libc/spec/posix.td b/libc/spec/posix.td
index ccbba46cc2149..de160960ab6ac 100644
--- a/libc/spec/posix.td
+++ b/libc/spec/posix.td
@@ -630,6 +630,20 @@ def POSIX : StandardSpec<"POSIX"> {
]
>;
+ HeaderSpec Sched = HeaderSpec<
+ "sched.h",
+ [], // Macros
+ [PidT, SizeTType, CpuSetT], // Types
+ [], // Enumerations
+ [
+ FunctionSpec<
+ "sched_yield",
+ RetValSpec<IntType>,
+ []
+ >,
+ ]
+ >;
+
HeaderSpec String = HeaderSpec<
"string.h",
[
@@ -1300,6 +1314,7 @@ def POSIX : StandardSpec<"POSIX"> {
Errno,
FCntl,
PThread,
+ Sched,
Signal,
Spawn,
StdIO,
diff --git a/libc/src/sched/CMakeLists.txt b/libc/src/sched/CMakeLists.txt
index 47d6c8fa245ed..7b55be8a7156e 100644
--- a/libc/src/sched/CMakeLists.txt
+++ b/libc/src/sched/CMakeLists.txt
@@ -16,6 +16,13 @@ add_entrypoint_object(
.${LIBC_TARGET_OS}.sched_setaffinity
)
+add_entrypoint_object(
+ sched_yield
+ ALIAS
+ DEPENDS
+ .${LIBC_TARGET_OS}.sched_yield
+)
+
add_entrypoint_object(
__sched_getcpucount
ALIAS
diff --git a/libc/src/sched/linux/CMakeLists.txt b/libc/src/sched/linux/CMakeLists.txt
index 82d3ab5c3a5ca..895ce1c202347 100644
--- a/libc/src/sched/linux/CMakeLists.txt
+++ b/libc/src/sched/linux/CMakeLists.txt
@@ -30,4 +30,16 @@ add_entrypoint_object(
../sched_getcpucount.h
DEPENDS
libc.include.sched
+ )
+
+add_entrypoint_object(
+ sched_yield
+ SRCS
+ sched_yield.cpp
+ HDRS
+ ../sched_yield.h
+ DEPENDS
+ libc.include.sys_syscall
+ libc.src.__support.OSUtil.osutil
+ libc.src.errno.errno
)
diff --git a/libc/src/sched/linux/sched_yield.cpp b/libc/src/sched/linux/sched_yield.cpp
new file mode 100644
index 0000000000000..64495c018898c
--- /dev/null
+++ b/libc/src/sched/linux/sched_yield.cpp
@@ -0,0 +1,29 @@
+//===-- Implementation of sched_yield -------------------------------------===//
+//
+// 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/sched/sched_yield.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+#include "src/errno/libc_errno.h"
+
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, sched_yield, ()) {
+ long ret = __llvm_libc::syscall_impl(SYS_sched_yield);
+ // As of writing this, yield() cannot fail
+ if (ret < 0) {
+ libc_errno = -ret;
+ return -1;
+ }
+ return 0;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/sched/sched_yield.h b/libc/src/sched/sched_yield.h
new file mode 100644
index 0000000000000..a64950039cdc8
--- /dev/null
+++ b/libc/src/sched/sched_yield.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for sched_yield -------------------*- 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_SCHED_SCHED_YIELD_H
+#define LLVM_LIBC_SRC_SCHED_SCHED_YIELD_H
+
+namespace __llvm_libc {
+
+int sched_yield(void);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SCHED_SCHED_YIELD_H
diff --git a/libc/test/src/sched/CMakeLists.txt b/libc/test/src/sched/CMakeLists.txt
index ad4dfdb553e1b..16ed8920e28f1 100644
--- a/libc/test/src/sched/CMakeLists.txt
+++ b/libc/test/src/sched/CMakeLists.txt
@@ -16,6 +16,17 @@ add_libc_unittest(
libc.test.errno_setter_matcher
)
+add_libc_unittest(
+ yield_test
+ SUITE
+ libc_sched_unittests
+ SRCS
+ yield_test.cpp
+ DEPENDS
+ libc.src.errno.errno
+ libc.src.sched.sched_yield
+)
+
add_libc_unittest(
cpu_count_test
SUITE
diff --git a/libc/test/src/sched/yield_test.cpp b/libc/test/src/sched/yield_test.cpp
new file mode 100644
index 0000000000000..ffa7f667cadff
--- /dev/null
+++ b/libc/test/src/sched/yield_test.cpp
@@ -0,0 +1,19 @@
+//===-- Unittests for sched_yield -----------------------------------------===//
+//
+// 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/errno/libc_errno.h"
+#include "src/sched/sched_yield.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcSchedYieldTest, SmokeTest) {
+ libc_errno = 0;
+ // sched_yield() always succeeds, just do a basic test that errno/ret are
+ // properly 0.
+ ASSERT_EQ(__llvm_libc::sched_yield(), 0);
+ ASSERT_EQ(libc_errno, 0);
+}
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