[clang] [KeyInstr] Add release note & update option (PR #148244)

[Orlando Cazalet-Hyams via cfe-commits]

https://github.com/OCHyams updated https://github.com/llvm/llvm-project/pull/148244

>From e31f415c4a1ba18f771a6119bee2bc11f4f705bb Mon Sep 17 00:00:00 2001
From: Orlando Cazalet-Hyams <orlando.hyams at sony.com>
Date: Fri, 11 Jul 2025 14:35:12 +0100
Subject: [PATCH 1/3] notes and helptext

---
 clang/docs/ReleaseNotes.rst           | 2 ++
 clang/include/clang/Driver/Options.td | 4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index bee71cf296ac3..9fa0d182ead25 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -354,6 +354,8 @@ New Compiler Flags
 
 - New option ``-ignore-pch`` added to disable precompiled headers. It overrides ``-emit-pch`` and ``-include-pch``. (#GH142409, `PCHDocs <https://clang.llvm.org/docs/UsersManual.html#ignoring-a-pch-file>`_).
 
+- New options ``-g[no-]key-instructions`` added, disabled by default. Reduces jumpiness of debug stepping for optimized code in some debuggers (not LLDB at this time). Not recommended for use without optimizations. DWARF only. Note both the positive and negative flags imply ``-g``.
+
 Deprecated Compiler Flags
 -------------------------
 
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 9911d752966e3..cc21e73e43fe6 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4705,8 +4705,8 @@ defm key_instructions : BoolGOption<"key-instructions",
     CodeGenOpts<"DebugKeyInstructions">, DefaultFalse,
     NegFlag<SetFalse>, PosFlag<SetTrue, [], [],
         "Enable Key Instructions, which reduces the jumpiness of optimized code stepping (DWARF only)."
-        " Requires LLVM built with LLVM_EXPERIMENTAL_KEY_INSTRUCTIONS.">,
-    BothFlags<[HelpHidden], [ClangOption, CLOption, CC1Option]>>;
+        " Implies -g.">,
+    BothFlags<[], [ClangOption, CLOption, CC1Option]>>;
 def headerpad__max__install__names : Joined<["-"], "headerpad_max_install_names">;
 def help : Flag<["-", "--"], "help">,
     Visibility<[ClangOption, CC1Option, CC1AsOption,

>From 2474a23890da2f49670bec4e32bd07169aa40720 Mon Sep 17 00:00:00 2001
From: Orlando Cazalet-Hyams <orlando.hyams at sony.com>
Date: Fri, 11 Jul 2025 14:39:19 +0100
Subject: [PATCH 2/3] better help text

---
 clang/include/clang/Driver/Options.td | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index cc21e73e43fe6..a6ff105d1b6a4 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -4704,8 +4704,8 @@ def gno_embed_source : Flag<["-"], "gno-embed-source">, Group<g_flags_Group>,
 defm key_instructions : BoolGOption<"key-instructions",
     CodeGenOpts<"DebugKeyInstructions">, DefaultFalse,
     NegFlag<SetFalse>, PosFlag<SetTrue, [], [],
-        "Enable Key Instructions, which reduces the jumpiness of optimized code stepping (DWARF only)."
-        " Implies -g.">,
+        "Enable Key Instructions, which reduces the jumpiness of debug stepping in optimized C/C++ code"
+        " in some debuggers. DWARF only. Implies -g.">,
     BothFlags<[], [ClangOption, CLOption, CC1Option]>>;
 def headerpad__max__install__names : Joined<["-"], "headerpad_max_install_names">;
 def help : Flag<["-", "--"], "help">,

>From 40097d68a0af4afad16c7c9d28e7da527189aa6c Mon Sep 17 00:00:00 2001
From: Orlando Cazalet-Hyams <orlando.hyams at sony.com>
Date: Mon, 14 Jul 2025 09:57:05 +0100
Subject: [PATCH 3/3] check help is visible

---
 clang/test/DebugInfo/KeyInstructions/flag.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/test/DebugInfo/KeyInstructions/flag.cpp b/clang/test/DebugInfo/KeyInstructions/flag.cpp
index 93503dd4bdb4c..f5f438ac683ea 100644
--- a/clang/test/DebugInfo/KeyInstructions/flag.cpp
+++ b/clang/test/DebugInfo/KeyInstructions/flag.cpp
@@ -3,9 +3,9 @@
 //// Default: Off.
 // RUN: %clang -### -target x86_64 -c -gdwarf %s 2>&1 | FileCheck %s --check-prefixes=NO-KEY-INSTRUCTIONS
 
-//// Help hidden.
+//// Help.
 // RUN %clang --help | FileCheck %s --check-prefix=HELP
-// HELP-NOT: key-instructions
+// HELP: -gkey-instructions  Enable Key Instructions, which reduces the jumpiness of debug stepping in optimized C/C++ code in some debuggers. DWARF only. Implies -g.
 
 // KEY-INSTRUCTIONS: "-gkey-instructions"
 // KEY-INSTRUCTIONS: "-mllvm" "-dwarf-use-key-instructions"