[PowerPC] Update V18.1.0 release notes (#81631)

Adding PowerPC updates for clang and llvm into the V18.1.0 release
notes.

---------

Co-authored-by: Maryam Moghadas <[email protected]>

Author: maryammo

clang/docs/ReleaseNotes.rst

@@ -304,6 +304,10 @@ Non-comprehensive list of changes in this release
 
 * The version of Unicode used by Clang (primarily to parse identifiers) has been updated to 15.1.
 
+* Clang now defines macro ``__LLVM_INSTR_PROFILE_GENERATE`` when compiling with
+  PGO instrumentation profile generation, and ``__LLVM_INSTR_PROFILE_USE`` when
+  compiling with PGO profile use.
+
 New Compiler Flags
 ------------------
 
@@ -344,6 +348,8 @@ New Compiler Flags
   attribute the replaceable global new and delete operators behave normally
   (like other functions) with respect to visibility attributes, pragmas and
   options (e.g ``--fvisibility=``).
+* Full register names can be used when printing assembly via ``-mregnames``.
+  This option now matches the one used by GCC.
 
 Deprecated Compiler Flags
 -------------------------
@@ -363,6 +369,7 @@ Modified Compiler Flags
 * ``-fvisibility-global-new-delete-hidden`` is now a deprecated spelling of
   ``-fvisibility-global-new-delete=force-hidden`` (``-fvisibility-global-new-delete=``
   is new in this release).
+* ``-fprofile-update`` is enabled for ``-fprofile-generate``.
 
 Removed Compiler Flags
 -------------------------
@@ -860,6 +867,9 @@ Bug Fixes in This Version
   Fixes (`#78290 <https://github.com/llvm/llvm-project/issues/78290>`_)
 - Fixed assertion failure with deleted overloaded unary operators.
   Fixes (`#78314 <https://github.com/llvm/llvm-project/issues/78314>`_)
+- The XCOFF object file format does not support aliases to symbols having common
+  linkage. Clang now diagnoses the use of an alias for a common symbol when
+  compiling for AIX.
 
 - Clang now doesn't produce false-positive warning `-Wconstant-logical-operand`
   for logical operators in C23.
@@ -1261,6 +1271,16 @@ CUDA Support
 - Clang now supports CUDA SDK up to 12.3
 - Added support for sm_90a
 
+PowerPC Support
+^^^^^^^^^^^^^^^
+
+- Added ``nmmintrin.h`` to intrinsics headers.
+- Added ``__builtin_ppc_fence`` as barrier of code motion, and
+  ``__builtin_ppc_mffsl`` for corresponding instruction.
+- Supported ``__attribute__((target("tune=cpu")))``.
+- Emit ``float-abi`` module flag on 64-bit ELFv2 PowerPC targets if
+  ``long double`` type is used in current module.
+
 AIX Support
 ^^^^^^^^^^^
 
@@ -1269,6 +1289,10 @@ 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.
+- Inline assembler supports VSR register in pure digits.
+- Enabled ThinLTO support. Requires AIX 7.2 TL5 SP7 or newer, or AIX 7.3 TL2
+  or newer. Similar to the LTO support on AIX, ThinLTO is implemented with
+  the libLTO.so plugin.
 
 WebAssembly Support
 ^^^^^^^^^^^^^^^^^^^
@@ -1332,6 +1356,8 @@ libclang
 - Exposed arguments of ``clang::annotate``.
 - ``clang::getCursorKindForDecl`` now recognizes linkage specifications such as
   ``extern "C"`` and reports them as ``CXCursor_LinkageSpec``.
+- Changed the libclang library on AIX to export only the necessary symbols to
+  prevent issues of resolving to the wrong duplicate symbol.
 
 Static Analyzer
 ---------------

llvm/docs/ReleaseNotes.rst

@@ -164,6 +164,30 @@ Changes to the MIPS Backend
 Changes to the PowerPC Backend
 ------------------------------
 
+* LLJIT's JIT linker now defaults to JITLink on 64-bit ELFv2 targets.
+* Initial-exec TLS model is supported on AIX.
+* Implemented new resource based scheduling model of POWER7 and POWER8.
+* ``frexp`` libcall now references correct symbol name for ``fp128``.
+* Optimized materialization of 64-bit immediates, code generation of
+  ``vec_promote`` and atomics.
+* Global constant strings are pooled in the TOC under one entry to reduce the
+  number of entries in the TOC.
+* Added a number of missing Power10 extended mnemonics.
+* Added the SCV instruction.
+* Fixed register class for the paddi instruction.
+* Optimize VPERM and fix code order for swapping vector operands on LE.
+* Added various bug fixes and code gen improvements.
+
+AIX Support/improvements:
+
+* Support for a non-TOC-based access sequence for the local-exec TLS model (called small local-exec).
+* XCOFF toc-data peephole optimization and bug fixes.
+* Move less often used __ehinfo TOC entries to the end of the TOC section.
+* Fixed problems when the AIX libunwind unwinds starting from a signal handler
+  and the function that raised the signal happens to be a leaf function that
+  shares the stack frame with its caller or a leaf function that does not store
+  the stack frame backchain.
+
 Changes to the RISC-V Backend
 -----------------------------
 
@@ -317,6 +341,7 @@ Changes to the LLVM tools
 
 * llvm-symbolizer now treats invalid input as an address for which source
   information is not found.
+* Fixed big-endian support in llvm-symbolizer's DWARF location parser.
 * llvm-readelf now supports ``--extra-sym-info`` (``-X``) to display extra
   information (section name) when showing symbols.
 
@@ -328,6 +353,13 @@ Changes to the LLVM tools
 * llvm-objcopy now supports ``--gap-fill`` and ``--pad-to`` options, for
   ELF input and binary output files only.
 
+* Supported parsing XCOFF auxiliary symbols in obj2yaml.
+
+* ``llvm-ranlib`` now supports ``-X`` on AIX to specify the type of object file
+  ranlib should examine.
+
+* ``llvm-nm`` now supports ``--export-symbol`` to ignore the import symbol file.
+
 * llvm-rc and llvm-windres now accept file path references in ``.rc`` files
   concatenated from multiple string literals.
 
@@ -387,6 +419,12 @@ Changes to Sanitizers
 ---------------------
 * HWASan now defaults to detecting use-after-scope bugs.
 
+Changes to the Profile Runtime
+------------------------------
+
+* Public header ``profile/instr_prof_interface.h`` is added to declare four
+  API functions to fine tune profile collection.
+
 Other Changes
 -------------