[docs] Add clang release notes for LoongArch

Author: Ami-zhang

clang/docs/ReleaseNotes.rst

@@ -985,6 +985,36 @@ Windows Support
 LoongArch Support
 ^^^^^^^^^^^^^^^^^
 
+- Add support for OHOS on loongarch64.
+
+- Add inline asm support for the `q` constraint.
+
+- Add `same-address` constraint to the description of `-m[no]ld-seq-sa`.
+
+- Add target attribute support for function. Supported formats include:
+  * `arch=<arch>` strings, that specify the architecture features for a
+    function as per the `-march=<arch>` option.
+  * `tune=<cpu>` strings, that specify the tune-cpu cpu for a function as
+    per `-mtune`.
+  * `<feature>`/`no-<feature>` enables/disables the specific feature.
+
+- Only report the first range error if there is actually more than one for
+  `__builtin_loongarch_cacop_[wd]`.
+
+- Add support for the `_Float16` type. And fix incorrect ABI lowering of `_Float16`
+  in the case of structs containing fp16 that are eligible for passing via `GPR+FPR`
+  or `FPR+FPR`. Also fix `int16` -> `__fp16` conversion code gen, which uses generic LLVM
+  IR rather than `llvm.convert.to.fp16` intrinsics.
+
+- Add support for the `__bf16` type.
+
+- Fix `-mno-lsx` option not disabling LASX feature. When `-march` with LASX feature and
+  `-mno-lsx` options are used together, `-mno-lsx` fails to disable LASX, leaving
+  `HasFeatureLASX=true` and causing incorrect `__loongarch_sx/asx=1` macro definition.
+
+- Fix incorrect _BitInt(N>64) alignment. Now consistently uses 16-byte alignment for all
+  `_BitInt(N)` where N > 64.
+
 RISC-V Support
 ^^^^^^^^^^^^^^