[docs] Add llvm & clang release notes for LoongArch

Differential Revision: https://reviews.llvm.org/D156195

Author: SixWeining

clang/docs/ReleaseNotes.rst

@@ -897,6 +897,8 @@ LoongArch Support
   on LoongArch.
 - Unaligned memory accesses can be toggled by ``-m[no-]unaligned-access`` or the
   aliases ``-m[no-]strict-align``.
+- Non ``$``-prefixed GPR names (e.g. ``r4`` and ``a0``) are allowed in inlineasm
+  like GCC does.
 
 RISC-V Support
 ^^^^^^^^^^^^^^
@@ -1095,6 +1097,7 @@ Static Analyzer
 
 Sanitizers
 ----------
+- Several more sanitizers are now ported to LoongArch: MSan, DFsan, Profile, XRay and libFuzzer.
 
 Python Binding Changes
 ----------------------

llvm/docs/ReleaseNotes.rst

@@ -199,9 +199,13 @@ Changes to the Hexagon Backend
 Changes to the LoongArch Backend
 --------------------------------
 
+* Adds assembler/disassembler support for the LSX, LASX, LVZ and LBT ISA extensions.
 * The ``lp64s`` ABI is supported now and has been tested on Rust bare-matal target.
 * A target feature ``ual`` is introduced to allow unaligned memory accesses and
   this feature is enabled by default for generic 64-bit processors.
+* Adds support for the ``large`` code model, which is equivalent to GCC's ``extreme`` one.
+* Assorted codegen improvements.
+* llvm-objcopy now supports processing LoongArch objects.
 
 Changes to the MIPS Backend
 ---------------------------