[llvm-branch-commits] [clang] [llvm] [docs][Hexagon] Add 23.x release notes for Hexagon changes (PR #210848)

[Douglas Yung via llvm-branch-commits]

https://github.com/dyung updated https://github.com/llvm/llvm-project/pull/210848

>From a94ef183551cb95b9ca59e6ea016451f17d7f553 Mon Sep 17 00:00:00 2001
From: Brian Cain <brian.cain at oss.qualcomm.com>
Date: Mon, 20 Jul 2026 16:41:40 -0700
Subject: [PATCH] [docs][Hexagon] Add 23.x release notes for Hexagon changes
 (NFC)

---
 clang/docs/ReleaseNotes.md | 13 +++++++++++++
 llvm/docs/ReleaseNotes.md  | 28 ++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/clang/docs/ReleaseNotes.md b/clang/docs/ReleaseNotes.md
index 5216f8a97af66..f4043d6c64a71 100644
--- a/clang/docs/ReleaseNotes.md
+++ b/clang/docs/ReleaseNotes.md
@@ -1140,6 +1140,19 @@ latest release, please see the [Clang Web Site](https://clang.llvm.org) or the
 
 #### AVR Support
 
+#### Hexagon Support
+
+- `H2` and `QURT` are now recognized as operating systems in the Hexagon
+  target triple. The driver can build against Picolibc for H2, and a
+  `--cstdlib` flag selects Picolibc.
+- RTSan, TySan, and the CFI indirect-call sanitizer now support Hexagon.
+  `-fsanitize=type` is enabled for Hexagon Linux.
+- `-ffixed-rXX` can now reserve caller-saved registers r16-r28.
+- ShadowCallStack (`-fsanitize=shadow-call-stack`) is supported.
+- The driver passes LTO options through to the Hexagon linker invocation.
+- `_GNU_SOURCE` is predefined for Hexagon C++ compilations.
+- `__HVX_IEEE_FP__` is defined when `-mhvx-ieee-fp` is enabled.
+
 #### SystemZ Support
 
 - Add support for `#pragma export` for z/OS. This is a pragma used to export functions and variables
diff --git a/llvm/docs/ReleaseNotes.md b/llvm/docs/ReleaseNotes.md
index a878e6e68c24a..36c8ed68cff28 100644
--- a/llvm/docs/ReleaseNotes.md
+++ b/llvm/docs/ReleaseNotes.md
@@ -237,6 +237,34 @@ Makes programs 10x faster by doing Special New Thing.
 
 ### Changes to the Hexagon Backend
 
+* v79 and later targets get code generation support for XQFloat, an
+  extended-precision floating point format, along with an extraneous
+  conversion removal pass and a post-register-allocation compliance checker.
+* IEEE HVX floating point intrinsics are automatically translated to their
+  QFloat equivalents on v79+ targets.
+* `vselect` can now be lowered for HVX.
+* Partial reduction intrinsics are now supported.
+* HVX gained V128i1/V64i1/V32i1 predicate load and store support.
+* The Machine Combiner pass is enabled for Hexagon.
+* A new AggressiveRDF copy propagation pass extends RDF copy propagation
+  with super-register and sub-register handling.
+* The HexagonGlobalScheduler pass was added.
+* ShadowCallStack (`-fsanitize=shadow-call-stack`) is now supported, along
+  with a corresponding multilib.
+* Stack clash protection can use `probe-stack=inline-asm`.
+* KCFI is now supported.
+* The CFI indirect-call sanitizer is now supported.
+* `-ffixed-rXX` can reserve caller-saved registers r16-r28.
+* A new HVX caller-save remark pass diagnoses call sites that force HVX
+  register spills.
+* Several Hexagon IR and MIR passes now emit optimization remarks.
+* XRay custom and typed events are now supported.
+* JITLink gained an ELF backend for Hexagon.
+* The `.reloc` assembler directive is now supported.
+* HVX build-vector lowering now reuses word splats for repeated words.
+* Sign-extend-then-multiply patterns are now recognized and lowered to
+  `vmpyh`.
+
 ### Changes to the LoongArch Backend
 
 * DWARF fission is now compatible with linker relaxations, allowing `-gsplit-dwarf` and `-mrelax`