Add AIX/PPC Clang/LLVM release notes for LLVM 19.

Author: amy-kwan

clang/docs/ReleaseNotes.rst

@@ -1276,6 +1276,14 @@ RISC-V Support
   accesses may be created. ``-m[no-]strict-align`` applies to both scalar and
   vector.
 
+PowerPC Support
+^^^^^^^^^^^^^^^
+
+- Clang now emits errors for impossible ``__attribute__((musttail))``.
+- Added support for ``-mcpu=[pwr11 | power11]`` and ``-mtune=[pwr11 | power11]``.
+- Added support for ``builtin_cpu_supports`` on AIX, along with a subset of
+  features that can be queried.
+
 CUDA/HIP Language Changes
 ^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -1294,6 +1302,14 @@ AIX Support
   base is encoded as an immediate operand.
   This access sequence is not used for TLS variables larger than 32KB, and is
   currently only supported on 64-bit mode.
+- Introduced the options ``-mtocdata/-mno-tocdata`` to enable/disable TOC data
+  transformations for the listed suitable variables.
+- Introduced the ``-maix-shared-lib-tls-model-opt`` option to enable the tuning
+  of changing local-dynamic mode access(es) to initial-exec access(es) at the
+  function level on 64-bit mode.
+- Clang now emits errors for ``-gdwarf-5``.
+- Added the support of the OpenMP runtime libomp on AIX. OpenMP applications can be
+  compiled with ``-fopenmp`` and execute on AIX.
 
 NetBSD Support
 ^^^^^^^^^^^^^^
@@ -1451,6 +1467,7 @@ OpenMP Support
 --------------
 
 - Added support for the `[[omp::assume]]` attribute.
+- AIX added an include directory for ``omp.h`` at ``/opt/IBM/openxlCSDK/include/openmp``.
 
 Additional Information
 ======================

llvm/docs/ReleaseNotes.rst

@@ -113,6 +113,8 @@ Changes to TableGen
 Changes to Interprocedural Optimizations
 ----------------------------------------
 
+* Hot cold region splitting analysis improvements for overlapping cold regions.
+
 Changes to the AArch64 Backend
 ------------------------------
 
@@ -194,6 +196,16 @@ Changes to the MIPS Backend
 Changes to the PowerPC Backend
 ------------------------------
 
+* PPC big-endian Linux now supports ``-fpatchable-function-entry``.
+* PPC AIX now supports local-dynamic TLS mode.
+* PPC AIX saves the Git revision in binaries when built with LLVM_APPEND_VC_REV=ON.
+* PPC AIX now supports toc-data attribute for large code model.
+* PPC AIX now supports passing arguments by value having greater alignment than
+  the pointer size. Currently only compatible with the IBM XL C compiler.
+* Add support for the per global code model attribute on AIX.
+* Support spilling non-volatile registers for traceback table accuracy on AIX.
+* Codegen improvements and bug fixes.
+
 Changes to the RISC-V Backend
 -----------------------------
 
@@ -436,6 +448,8 @@ Changes to the LLVM tools
   be disabled by ``--no-verify-note-sections``. (`#90458
   <https://github.com/llvm/llvm-project/pull/90458>`).
 
+* llvm-objdump now supports the ``--file-headers`` option for XCOFF object files.
+
 Changes to LLDB
 ---------------------------------