[libc] Add a skeleton for C standard condition variable functions.

This patch adds a skeleton as a preparatory step for the next patch which
adds the actual implementations of the condition variable functions.

Reviewed By: michaelrj

Differential Revision: https://reviews.llvm.org/D108947

12 files changed, 272 insertions, 0 deletions

diff --git a/libc/src/threads/CMakeLists.txt b/libc/src/threads/CMakeLists.txt
index a5d9589e44f3..de72701bef75 100644
--- a/libc/src/threads/CMakeLists.txt
+++ b/libc/src/threads/CMakeLists.txt
@@ -50,3 +50,38 @@ add_entrypoint_object(
   DEPENDS
     .${LIBC_TARGET_OS}.mtx_unlock
 )
+
+add_entrypoint_object(
+  cnd_init
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.cnd_init
+)
+
+add_entrypoint_object(
+  cnd_destroy
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.cnd_destroy
+)
+
+add_entrypoint_object(
+  cnd_wait
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.cnd_wait
+)
+
+add_entrypoint_object(
+  cnd_signal
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.cnd_signal
+)
+
+add_entrypoint_object(
+  cnd_broadcast
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.cnd_broadcast
+)
diff --git a/libc/src/threads/cnd_broadcast.h b/libc/src/threads/cnd_broadcast.h
new file mode 100644
index 000000000000..219341bc4498
--- /dev/null
+++ b/libc/src/threads/cnd_broadcast.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for cnd_broadcast function --------*- 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_THREADS_CND_BROADCAST_H
+#define LLVM_LIBC_SRC_THREADS_CND_BROADCAST_H
+
+#include "include/threads.h"
+
+namespace __llvm_libc {
+
+int cnd_broadcast(cnd_t *cond);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_THREADS_CND_BROADCAST_H
diff --git a/libc/src/threads/cnd_destroy.h b/libc/src/threads/cnd_destroy.h
new file mode 100644
index 000000000000..4fa1ea18b5e2
--- /dev/null
+++ b/libc/src/threads/cnd_destroy.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for cnd_destroy function ----------*- 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_THREADS_CND_DESTROY_H
+#define LLVM_LIBC_SRC_THREADS_CND_DESTROY_H
+
+#include "include/threads.h"
+
+namespace __llvm_libc {
+
+void cnd_destroy(cnd_t *cond);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_THREADS_CND_DESTROY_H
diff --git a/libc/src/threads/cnd_init.h b/libc/src/threads/cnd_init.h
new file mode 100644
index 000000000000..8c14c88342e3
--- /dev/null
+++ b/libc/src/threads/cnd_init.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for cnd_init function -------------*- 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_THREADS_CND_INIT_H
+#define LLVM_LIBC_SRC_THREADS_CND_INIT_H
+
+#include "include/threads.h"
+
+namespace __llvm_libc {
+
+int cnd_init(cnd_t *cond);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_THREADS_CND_INIT_H
diff --git a/libc/src/threads/cnd_signal.h b/libc/src/threads/cnd_signal.h
new file mode 100644
index 000000000000..d85802dda484
--- /dev/null
+++ b/libc/src/threads/cnd_signal.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for cnd_signal function -----------*- 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_THREADS_CND_SIGNAL_H
+#define LLVM_LIBC_SRC_THREADS_CND_SIGNAL_H
+
+#include "include/threads.h"
+
+namespace __llvm_libc {
+
+int cnd_signal(cnd_t *cond);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_THREADS_CND_SIGNAL_H
diff --git a/libc/src/threads/cnd_wait.h b/libc/src/threads/cnd_wait.h
new file mode 100644
index 000000000000..5f9ac0884676
--- /dev/null
+++ b/libc/src/threads/cnd_wait.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for cnd_wait function -------------*- 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_THREADS_CND_WAIT_H
+#define LLVM_LIBC_SRC_THREADS_CND_WAIT_H
+
+#include "include/threads.h"
+
+namespace __llvm_libc {
+
+int cnd_wait(cnd_t *cond, mtx_t *mutex);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_THREADS_CND_WAIT_H
diff --git a/libc/src/threads/linux/CMakeLists.txt b/libc/src/threads/linux/CMakeLists.txt
index b28850b94d8f..abf38fabb8ae 100644
--- a/libc/src/threads/linux/CMakeLists.txt
+++ b/libc/src/threads/linux/CMakeLists.txt
@@ -113,3 +113,58 @@ add_entrypoint_object(
     .threads_utils
     libc.include.threads
 )
+
+add_entrypoint_object(
+  cnd_init
+  SRCS
+    cnd_init.cpp
+  HDRS
+    ../cnd_init.h
+  DEPENDS
+    .threads_utils
+    libc.include.threads
+)
+
+add_entrypoint_object(
+  cnd_destroy
+  SRCS
+    cnd_destroy.cpp
+  HDRS
+    ../cnd_destroy.h
+  DEPENDS
+    .threads_utils
+    libc.include.threads
+)
+
+add_entrypoint_object(
+  cnd_wait
+  SRCS
+    cnd_wait.cpp
+  HDRS
+    ../cnd_wait.h
+  DEPENDS
+    .threads_utils
+    libc.include.threads
+)
+
+add_entrypoint_object(
+  cnd_signal
+  SRCS
+    cnd_signal.cpp
+  HDRS
+    ../cnd_signal.h
+  DEPENDS
+    .threads_utils
+    libc.include.threads
+)
+
+add_entrypoint_object(
+  cnd_broadcast
+  SRCS
+    cnd_broadcast.cpp
+  HDRS
+    ../cnd_broadcast.h
+  DEPENDS
+    .threads_utils
+    libc.include.threads
+)
diff --git a/libc/src/threads/linux/cnd_broadcast.cpp b/libc/src/threads/linux/cnd_broadcast.cpp
new file mode 100644
index 000000000000..e10f9fa6c228
--- /dev/null
+++ b/libc/src/threads/linux/cnd_broadcast.cpp
@@ -0,0 +1,16 @@
+//===-- Linux implementation of the cnd_broadcast function ----------------===//
+//
+// 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/threads/cnd_broadcast.h"
+#include "src/__support/common.h"
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, cnd_broadcast, (cnd_t * cond)) { return thrd_success; }
+
+} // namespace __llvm_libc
diff --git a/libc/src/threads/linux/cnd_destroy.cpp b/libc/src/threads/linux/cnd_destroy.cpp
new file mode 100644
index 000000000000..ac8a852a9739
--- /dev/null
+++ b/libc/src/threads/linux/cnd_destroy.cpp
@@ -0,0 +1,16 @@
+//===-- Linux implementation of the cnd_destroy function ------------------===//
+//
+// 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/threads/cnd_destroy.h"
+#include "src/__support/common.h"
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(void, cnd_destroy, (cnd_t * cond)) { }
+
+} // namespace __llvm_libc
diff --git a/libc/src/threads/linux/cnd_init.cpp b/libc/src/threads/linux/cnd_init.cpp
new file mode 100644
index 000000000000..f034695227b7
--- /dev/null
+++ b/libc/src/threads/linux/cnd_init.cpp
@@ -0,0 +1,16 @@
+//===-- Linux implementation of the cnd_init function ---------------------===//
+//
+// 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/threads/cnd_init.h"
+#include "src/__support/common.h"
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, cnd_init, (cnd_t * cond)) { return thrd_success; }
+
+} // namespace __llvm_libc
diff --git a/libc/src/threads/linux/cnd_signal.cpp b/libc/src/threads/linux/cnd_signal.cpp
new file mode 100644
index 000000000000..8ef16a355e7b
--- /dev/null
+++ b/libc/src/threads/linux/cnd_signal.cpp
@@ -0,0 +1,16 @@
+//===-- Linux implementation of the cnd_signal function -------------------===//
+//
+// 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/threads/cnd_signal.h"
+#include "src/__support/common.h"
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, cnd_signal, (cnd_t * cond)) { return thrd_success; }
+
+} // namespace __llvm_libc
diff --git a/libc/src/threads/linux/cnd_wait.cpp b/libc/src/threads/linux/cnd_wait.cpp
new file mode 100644
index 000000000000..e2dda46d2dc9
--- /dev/null
+++ b/libc/src/threads/linux/cnd_wait.cpp
@@ -0,0 +1,18 @@
+//===-- Linux implementation of the cnd_wait function ---------------------===//
+//
+// 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/threads/cnd_wait.h"
+#include "src/__support/common.h"
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, cnd_wait, (cnd_t * cond, mtx_t *mutex)) {
+  return thrd_success;
+}
+
+} // namespace __llvm_libc