[libc] Implement `timespec_get` #116102

petrhosek · 2024-11-13T20:18:12Z

timespec_get is C standard counterpart to POSIX clock_gettime. On Linux we simply use clock_gettime. On baremetal we introduce a new external API __llvm_libc_timespec_get_utc that should be implemented by the vendor.

`timespec_get` is C standard counterpart to POSIX `clock_gettime`. On Linux we simply use `clock_gettime`. On baremetal we introduce a new external API `__llvm_libc_time_utc_get` that should be implemented by the vendor.

llvmbot · 2024-11-13T20:18:36Z

@llvm/pr-subscribers-libc

Author: Petr Hosek (petrhosek)

Changes

timespec_get is C standard counterpart to POSIX clock_gettime. On Linux we simply use clock_gettime. On baremetal we introduce a new external API __llvm_libc_time_utc_get that should be implemented by the vendor.

Full diff: https://github.com/llvm/llvm-project/pull/116102.diff

18 Files Affected:

(modified) libc/config/baremetal/arm/entrypoints.txt (+1)
(modified) libc/config/baremetal/riscv/entrypoints.txt (+1)
(modified) libc/config/linux/aarch64/entrypoints.txt (+1)
(modified) libc/config/linux/riscv/entrypoints.txt (+1)
(modified) libc/config/linux/x86_64/entrypoints.txt (+1)
(modified) libc/include/llvm-libc-macros/time-macros.h (+2)
(modified) libc/newhdrgen/yaml/time.yaml (+7)
(modified) libc/src/__support/OSUtil/baremetal/CMakeLists.txt (+2)
(added) libc/src/__support/OSUtil/baremetal/time.cpp (+21)
(added) libc/src/__support/OSUtil/baremetal/time.h (+21)
(modified) libc/src/time/CMakeLists.txt (+7)
(added) libc/src/time/baremetal/CMakeLists.txt (+11)
(added) libc/src/time/baremetal/timespec_get.cpp (+25)
(modified) libc/src/time/linux/CMakeLists.txt (+13)
(added) libc/src/time/linux/timespec_get.cpp (+31)
(added) libc/src/time/timespec_get.h (+21)
(modified) libc/test/src/time/CMakeLists.txt (+10)
(added) libc/test/src/time/timespec_get_test.cpp (+32)

diff --git a/libc/config/baremetal/arm/entrypoints.txt b/libc/config/baremetal/arm/entrypoints.txt
index b85ae1119345dd..9027717acb4dae 100644
--- a/libc/config/baremetal/arm/entrypoints.txt
+++ b/libc/config/baremetal/arm/entrypoints.txt
@@ -209,6 +209,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.time.gmtime
     libc.src.time.gmtime_r
     libc.src.time.mktime
+    libc.src.time.timespec_get
 
     # internal entrypoints
     libc.startup.baremetal.init
diff --git a/libc/config/baremetal/riscv/entrypoints.txt b/libc/config/baremetal/riscv/entrypoints.txt
index 199a030ee6371e..afae2b3e082be3 100644
--- a/libc/config/baremetal/riscv/entrypoints.txt
+++ b/libc/config/baremetal/riscv/entrypoints.txt
@@ -205,6 +205,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.time.gmtime
     libc.src.time.gmtime_r
     libc.src.time.mktime
+    libc.src.time.timespec_get
 
     # internal entrypoints
     libc.startup.baremetal.init
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 74ca3742977a5f..effa5b12d87ac4 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -999,6 +999,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.time.mktime
     libc.src.time.nanosleep
     libc.src.time.time
+    libc.src.time.timespec_get
 
     # unistd.h entrypoints
     libc.src.unistd.__llvm_libc_syscall
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 5419462d4f5b3b..5a48baf104159f 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -937,6 +937,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.time.mktime
     libc.src.time.nanosleep
     libc.src.time.time
+    libc.src.time.timespec_get
 
     # unistd.h entrypoints
     libc.src.unistd.__llvm_libc_syscall
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 957e28bd66cc4c..7365b53e8add82 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -1082,6 +1082,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.time.mktime
     libc.src.time.nanosleep
     libc.src.time.time
+    libc.src.time.timespec_get
 
     # locale.h entrypoints
     libc.src.locale.localeconv
diff --git a/libc/include/llvm-libc-macros/time-macros.h b/libc/include/llvm-libc-macros/time-macros.h
index 6d49ed484d5d48..02f2f7bfa7051d 100644
--- a/libc/include/llvm-libc-macros/time-macros.h
+++ b/libc/include/llvm-libc-macros/time-macros.h
@@ -7,4 +7,6 @@
 #include "linux/time-macros.h"
 #endif
 
+#define TIME_UTC 1
+
 #endif // LLVM_LIBC_MACROS_TIME_MACROS_H
diff --git a/libc/newhdrgen/yaml/time.yaml b/libc/newhdrgen/yaml/time.yaml
index 69b40bef3160dd..3f745e5ee33868 100644
--- a/libc/newhdrgen/yaml/time.yaml
+++ b/libc/newhdrgen/yaml/time.yaml
@@ -96,3 +96,10 @@ functions:
     return_type: time_t
     arguments:
       - type: time_t *
+  - name: timespec_get
+    standard:
+      - stdc
+    return_type: int
+    arguments:
+      - type: struct timespec *
+      - type: int
diff --git a/libc/src/__support/OSUtil/baremetal/CMakeLists.txt b/libc/src/__support/OSUtil/baremetal/CMakeLists.txt
index 8f9200ad0bd96e..5b02709315f9b1 100644
--- a/libc/src/__support/OSUtil/baremetal/CMakeLists.txt
+++ b/libc/src/__support/OSUtil/baremetal/CMakeLists.txt
@@ -3,8 +3,10 @@ add_object_library(
   SRCS
     io.cpp
     exit.cpp
+    time.cpp
   HDRS
     io.h
+    time.h
   DEPENDS
     libc.src.__support.common
     libc.src.__support.CPP.string_view
diff --git a/libc/src/__support/OSUtil/baremetal/time.cpp b/libc/src/__support/OSUtil/baremetal/time.cpp
new file mode 100644
index 00000000000000..63f0624b4cda4e
--- /dev/null
+++ b/libc/src/__support/OSUtil/baremetal/time.cpp
@@ -0,0 +1,21 @@
+//===---------- Baremetal implementation of time utils ----------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "time.h"
+
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+extern "C" int __llvm_libc_time_utc_get(struct timespec *ts);
+
+int time_utc_get(struct timespec *ts) {
+  return __llvm_libc_time_utc_get(ts);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/OSUtil/baremetal/time.h b/libc/src/__support/OSUtil/baremetal/time.h
new file mode 100644
index 00000000000000..8c3ded377c7376
--- /dev/null
+++ b/libc/src/__support/OSUtil/baremetal/time.h
@@ -0,0 +1,21 @@
+//===---------- Baremetal implementation of time utils ----------*- 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___SUPPORT_OSUTIL_BAREMETAL_TIME_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_BAREMETAL_TIME_H
+
+#include "include/llvm-libc-types/struct_timespec.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int time_utc_get(struct timespec *ts);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_BAREMETAL_IO_H
diff --git a/libc/src/time/CMakeLists.txt b/libc/src/time/CMakeLists.txt
index b3318e7ca87fa5..f18e74a15e6fc2 100644
--- a/libc/src/time/CMakeLists.txt
+++ b/libc/src/time/CMakeLists.txt
@@ -111,6 +111,13 @@ add_entrypoint_object(
     .${LIBC_TARGET_OS}.time
 )
 
+add_entrypoint_object(
+  timespec_get
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.timespec_get
+)
+
 add_entrypoint_object(
   clock
   ALIAS
diff --git a/libc/src/time/baremetal/CMakeLists.txt b/libc/src/time/baremetal/CMakeLists.txt
new file mode 100644
index 00000000000000..4bddfa691d7c2a
--- /dev/null
+++ b/libc/src/time/baremetal/CMakeLists.txt
@@ -0,0 +1,11 @@
+add_entrypoint_object(
+  timespec_get
+  SRCS
+    timespec_get.cpp
+  HDRS
+    ../timespec_get.h
+  DEPENDS
+    libc.hdr.time_macros
+    libc.hdr.types.struct_timespec
+    libc.src.__support.OSUtil.osutil
+)
diff --git a/libc/src/time/baremetal/timespec_get.cpp b/libc/src/time/baremetal/timespec_get.cpp
new file mode 100644
index 00000000000000..93ae4e9c9d1731
--- /dev/null
+++ b/libc/src/time/baremetal/timespec_get.cpp
@@ -0,0 +1,25 @@
+//===-- Implementation of timespec_get for baremetal ----------------------===//
+//
+// 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/time/timespec_get.h"
+#include "hdr/time_macros.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/OSUtil/baremetal/time.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, timespec_get, (struct timespec *ts, int base)) {
+  if (base != TIME_UTC) {
+    return 0;
+  }
+
+  return time_utc_get(ts);
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/time/linux/CMakeLists.txt b/libc/src/time/linux/CMakeLists.txt
index c15fb44ad5d123..31fd7d1e64c85c 100644
--- a/libc/src/time/linux/CMakeLists.txt
+++ b/libc/src/time/linux/CMakeLists.txt
@@ -11,6 +11,19 @@ add_entrypoint_object(
     libc.src.errno.errno
 )
 
+add_entrypoint_object(
+  timespec_get
+  SRCS
+    timespec_get.cpp
+  HDRS
+    ../timespec_get.h
+  DEPENDS
+    libc.hdr.time_macros
+    libc.hdr.types.struct_timespec
+    libc.src.__support.time.linux.clock_gettime
+    libc.src.errno.errno
+)
+
 add_entrypoint_object(
   clock
   SRCS
diff --git a/libc/src/time/linux/timespec_get.cpp b/libc/src/time/linux/timespec_get.cpp
new file mode 100644
index 00000000000000..fa236cd3eaebee
--- /dev/null
+++ b/libc/src/time/linux/timespec_get.cpp
@@ -0,0 +1,31 @@
+//===-- Implementation of timespec_get for Linux --------------------------===//
+//
+// 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/time/timespec_get.h"
+#include "hdr/time_macros.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/time/linux/clock_gettime.h"
+#include "src/errno/libc_errno.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, timespec_get, (struct timespec *ts, int base)) {
+  if (base != TIME_UTC) {
+    return 0;
+  }
+
+  auto result = internal::clock_gettime(CLOCK_REALTIME, ts);
+  if (!result.has_value()) {
+    libc_errno = result.error();
+    return 0;
+  }
+  return base;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/time/timespec_get.h b/libc/src/time/timespec_get.h
new file mode 100644
index 00000000000000..32ba159a941606
--- /dev/null
+++ b/libc/src/time/timespec_get.h
@@ -0,0 +1,21 @@
+//===-- Implementation header of timespec_get --------------------*- 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_TIME_TIMESPEC_GET_H
+#define LLVM_LIBC_SRC_TIME_TIMESPEC_GET_H
+
+#include "src/__support/macros/config.h"
+#include <time.h>
+
+namespace LIBC_NAMESPACE_DECL {
+
+int timespec_get(struct timespec *ts, int base);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_TIME_TIMESPEC_GET_H
diff --git a/libc/test/src/time/CMakeLists.txt b/libc/test/src/time/CMakeLists.txt
index bba01f063fed27..7151526b72b26d 100644
--- a/libc/test/src/time/CMakeLists.txt
+++ b/libc/test/src/time/CMakeLists.txt
@@ -162,6 +162,16 @@ add_libc_unittest(
     libc.src.errno.errno
 )
 
+add_libc_test(
+  timespec_get_test
+  SUITE
+    libc_time_unittests
+  SRCS
+    timespec_get_test.cpp
+  DEPENDS
+    libc.src.time.timespec_get
+)
+
 add_libc_test(
   clock_test
   SUITE
diff --git a/libc/test/src/time/timespec_get_test.cpp b/libc/test/src/time/timespec_get_test.cpp
new file mode 100644
index 00000000000000..5bbd3db651d8a7
--- /dev/null
+++ b/libc/test/src/time/timespec_get_test.cpp
@@ -0,0 +1,32 @@
+//===-- Unittests for timespec_get ----------------------------------------===//
+//
+// 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/macros/properties/architectures.h"
+#include "src/time/timespec_get.h"
+#include "test/UnitTest/Test.h"
+
+#include <time.h>
+
+TEST(LlvmLibcTimespecGet, Utc) {
+#ifndef LIBC_TARGET_ARCH_IS_GPU
+  timespec ts;
+  int result;
+  result = LIBC_NAMESPACE::timespec_get(&ts, TIME_UTC);
+  ASSERT_EQ(result, TIME_UTC);
+  ASSERT_GT(ts.tv_sec, time_t(0));
+#endif
+}
+
+TEST(LlvmLibcTimespecGet, Unknown) {
+#ifndef LIBC_TARGET_ARCH_IS_GPU
+  timespec ts;
+  int result;
+  result = LIBC_NAMESPACE::timespec_get(&ts, 0);
+  ASSERT_EQ(result, 0);
+#endif
+}

github-actions · 2024-11-13T20:21:49Z

✅ With the latest revision this PR passed the C/C++ code formatter.

nickdesaulniers

Thanks for the patch!

libc/src/time/timespec_get.h

libc/test/src/time/timespec_get_test.cpp

nickdesaulniers · 2024-11-14T16:38:01Z

libc/test/src/time/timespec_get_test.cpp

+  int result;
+  result = LIBC_NAMESPACE::timespec_get(&ts, 0);
+  ASSERT_EQ(result, 0);
+#endif


How come these tests are disabled on the GPU?

GPU doesn't support UTC clock, it only implements monotonic clock. I could do the same for TIME_MONOTONIC and for TIME_UTC just return 0. @jhuber6 what do you think?

libc/src/time/linux/timespec_get.cpp

nickdesaulniers · 2024-11-14T16:44:43Z

libc/src/time/linux/timespec_get.cpp

+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, timespec_get, (struct timespec * ts, int base)) {
+  if (base != TIME_UTC) {


Please file a TODO (then link to it from a comment in the sources) about supporting the other specified bases (TIME_MONOTONIC, TIME_ACTIVE, and TIME_THREAD_ACTIVE). Especially since 7.29.2.6.5 recommends:

Because of its wider value range and improved indications on error, timespec_get with time base TIME_ACTIVE should be used instead of clock by new code whenever possible.

I wasn't aware of these, looks they were added in the latest standard (and aren't even mentioned on https://en.cppreference.com/w/c/chrono/timespec_get). I implemented all of them for Linux since it was straightforward.

libc/src/__support/OSUtil/baremetal/time.cpp

clock_gettime is a POSIX API that may not be available on platforms like baremetal; timespec_get is the C11 equivalent. This change adds support for using timespec_get instead of clock_gettime to improve compatibility with non-POSIX platforms. For now, this is only enabled with LLVM libc which implemented timespec_get in llvm#116102, but in the future this can be expanded to other platforms.

michaelrj-google

LGTM

michaelrj-google · 2024-11-22T21:26:07Z

libc/spec/stdc.td

+          FunctionSpec<
+              "timespec_get",
+              RetValSpec<IntType>,
+              [
+                ArgSpec<StructTimeSpecPtr>,
+                ArgSpec<IntType>,
+              ]
+          >,


since #117220 is close to landing, it might be best to skip adding anything to the old headergen files.

…timespec_get is defined After llvm/llvm-project#116102 we shouldn't need that workaround anymore. Original-Bug: 382538608 Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/infra/recipes/+/1169452 Original-Revision: d3ff723f1c9a4cfc412452714d61b8169a4bff36 GitOrigin-RevId: 3f506a9f38779518d8bf23fa7f6d45d87af6ace6 Change-Id: I69d8386c90aaa0ef5c529fc0160a699762f878a2

clock_gettime is a POSIX API that may not be available on platforms like baremetal; timespec_get is the C11 equivalent. This change adds support for using timespec_get instead of clock_gettime to improve compatibility with non-POSIX platforms. For now, this is only enabled with LLVM libc which implemented timespec_get in #116102, but in the future this can be expanded to other platforms. Related to #84879.

[libc] Implement timespec_get

f0f442d

`timespec_get` is C standard counterpart to POSIX `clock_gettime`. On Linux we simply use `clock_gettime`. On baremetal we introduce a new external API `__llvm_libc_time_utc_get` that should be implemented by the vendor.

petrhosek added the libc label Nov 13, 2024

petrhosek requested review from nickdesaulniers and michaelrj-google November 13, 2024 20:18

petrhosek added 2 commits November 13, 2024 13:56

Rename __llvm_libc_time_utc_get to __llvm_libc_timespec_get_utc

9fc2d09

Formatting

5560670

nickdesaulniers reviewed Nov 14, 2024

View reviewed changes

libc/src/__support/OSUtil/baremetal/time.cpp Outdated Show resolved Hide resolved

Address review feedback

d7c77be

nickdesaulniers approved these changes Nov 19, 2024

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petrhosek added 3 commits November 20, 2024 01:09

Avoid introducing new __support file for simplicity

4c65922

Support old hdrgen

0d52071

Support gpu

f4edc9b

petrhosek mentioned this pull request Nov 22, 2024

[libcxx] Support for using timespec_get #117362

Merged

michaelrj-google approved these changes Nov 22, 2024

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petrhosek merged commit b8daa45 into llvm:main Dec 2, 2024
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