[clang] [NFC][Docs] Documenting __builtin_cpu_supports. (PR #84098)

[Pavel Iliin via cfe-commits]

https://github.com/ilinpv updated https://github.com/llvm/llvm-project/pull/84098

>From 528af71d043d306a4aeb5c448a0780fa42644c15 Mon Sep 17 00:00:00 2001
From: Pavel Iliin <pavel.iliin at arm.com>
Date: Wed, 6 Mar 2024 00:23:36 +0000
Subject: [PATCH 1/3] [NFC][Docs] Documenting __builtin_cpu_supports.

---
 clang/docs/LanguageExtensions.rst | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index bcd69198eafdbe..f939d1c765e91a 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -2799,6 +2799,34 @@ counter's true frequency will need to be provided by the user.
 
 Query for this feature with ``__has_builtin(__builtin_readsteadycounter)``.
 
+``__builtin_cpu_supports``
+--------------------------
+
+**Syntax**:
+
+.. code-block:: c++
+
+  int __builtin_cpu_supports(const char *features);
+
+**Example of Use:**:
+
+.. code-block:: c++
+
+  if (__builtin_cpu_supports("sve"))
+    sve_code();
+
+**Description**:
+
+The ``__builtin_cpu_supports`` function detects at runtime if target CPU
+supports features specified in string argument. It returns positive integer
+if all features are supported and 0 otherwise. Names of features and format is
+target specific. For example on AArch64 features are combined using ``+`` like
+this ``__builtin_cpu_supports("flagm+sha3+lse+rcpc2+fcma+memtag+bti+sme2")``.
+If feature name is not supported or format is wrong, compiler will issue a
+warning and replace builtin by constant 0.
+
+Query for this feature with ``__has_builtin(__builtin_cpu_supports)``.
+
 ``__builtin_dump_struct``
 -------------------------
 

>From 165d1f0a360f47c2419eef1c4ab1c54d826b609a Mon Sep 17 00:00:00 2001
From: Pavel Iliin <Pavel.Iliin at arm.com>
Date: Wed, 6 Mar 2024 11:19:20 +0000
Subject: [PATCH 2/3] Update clang/docs/LanguageExtensions.rst

Co-authored-by: Jon Roelofs <jroelofs at gmail.com>
---
 clang/docs/LanguageExtensions.rst | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index f939d1c765e91a..96b76273c71166 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -2817,13 +2817,13 @@ Query for this feature with ``__has_builtin(__builtin_readsteadycounter)``.
 
 **Description**:
 
-The ``__builtin_cpu_supports`` function detects at runtime if target CPU
-supports features specified in string argument. It returns positive integer
-if all features are supported and 0 otherwise. Names of features and format is
+The ``__builtin_cpu_supports`` function detects at runtime if the target CPU
+supports features specified in string argument. It returns a positive integer
+if all features are supported and 0 otherwise. Names of features and format are
 target specific. For example on AArch64 features are combined using ``+`` like
 this ``__builtin_cpu_supports("flagm+sha3+lse+rcpc2+fcma+memtag+bti+sme2")``.
-If feature name is not supported or format is wrong, compiler will issue a
-warning and replace builtin by constant 0.
+If a feature name is not supported or the format is wrong, the compiler will issue a
+warning and replace builtin by the constant 0.
 
 Query for this feature with ``__has_builtin(__builtin_cpu_supports)``.
 

>From 280583a3f8fabb544b549feffbd4e7bb27808bc3 Mon Sep 17 00:00:00 2001
From: Pavel Iliin <pavel.iliin at arm.com>
Date: Wed, 6 Mar 2024 15:48:58 +0000
Subject: [PATCH 3/3] Addressing comments to __builtin_cpu_supports
 description.

---
 clang/docs/LanguageExtensions.rst | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index 96b76273c71166..2b54dffd058a35 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -2817,13 +2817,13 @@ Query for this feature with ``__has_builtin(__builtin_readsteadycounter)``.
 
 **Description**:
 
-The ``__builtin_cpu_supports`` function detects at runtime if the target CPU
-supports features specified in string argument. It returns a positive integer
-if all features are supported and 0 otherwise. Names of features and format are
-target specific. For example on AArch64 features are combined using ``+`` like
-this ``__builtin_cpu_supports("flagm+sha3+lse+rcpc2+fcma+memtag+bti+sme2")``.
-If a feature name is not supported or the format is wrong, the compiler will issue a
-warning and replace builtin by the constant 0.
+The ``__builtin_cpu_supports`` function detects if the run-time CPU supports
+features specified in string argument. It returns a positive integer if all
+features are supported and 0 otherwise. Feature names are target specific. On
+AArch64 features are combined using ``+`` like this
+``__builtin_cpu_supports("flagm+sha3+lse+rcpc2+fcma+memtag+bti+sme2")``.
+If a feature name is not supported, Clang will issue a warning and replace
+builtin by the constant 0.
 
 Query for this feature with ``__has_builtin(__builtin_cpu_supports)``.