RFR: JDK-8308288: Fix xlc17 clang warnings and build errors in hotspot

[Goetz Lindenmaier]

On Fri, 2 Jun 2023 11:28:45 GMT, JoKern65 <duke at openjdk.org> wrote:

> This pr is a split off from JDK-8308288 : Fix xlc17 clang warnings in shared code https://github.com/openjdk/jdk/pull/14146
> It handles the part in hotspot.
> 
> It handles the error introduced by a redefine of malloc in stdlib.h resulting in the following build error:
> 
> /data/d042520/pr/jdk/src/hotspot/share/runtime/os.cpp:616:5: error: no member named '_vec_malloc' in 'LogTag'; did you mean 'vec_malloc'?
>     log_warning(malloc, free)("ptr caught: " PTR_FORMAT, p2i(ptr));
>     ^~~~~~~~~~~~~~~~~~~~~~~~~
> /data/d042520/pr/jdk/src/hotspot/share/logging/log.hpp:46:28: note: expanded from macro 'log_warning'
> #define log_warning(...) (!log_is_enabled(Warning, __VA_ARGS__)) ? (void)0 : LogImpl<LOG_TAGS(__VA_ARGS__)>::write<LogLevel::Warning>
>                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> /data/d042520/pr/jdk/src/hotspot/share/logging/log.hpp:68:45: note: expanded from macro 'log_is_enabled'
> #define log_is_enabled(level, ...) (LogImpl<LOG_TAGS(__VA_ARGS__)>::is_level(LogLevel::level))
>                                             ^~~~~~~~~~~~~~~~~~~~~
> /data/d042520/pr/jdk/src/hotspot/share/logging/logTag.hpp:221:38: note: expanded from macro 'LOG_TAGS'
> #define LOG_TAGS(...) EXPAND_VARARGS(LOG_TAGS_EXPANDED(__VA_ARGS__, _NO_TAG, _NO_TAG, _NO_TAG, _NO_TAG, _NO_TAG, _NO_TAG))
>                                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> /data/d042520/pr/jdk/src/hotspot/share/logging/logTag.hpp:217:57: note: expanded from macro 'LOG_TAGS_EXPANDED'
> #define LOG_TAGS_EXPANDED(T0, T1, T2, T3, T4, T5, ...)  PREFIX_LOG_TAG(T0), PREFIX_LOG_TAG(T1), PREFIX_LOG_TAG(T2), \
>                                                         ^~~~~~~~~~~~~~~~~~
>    ... (rest of output omitted)
> 
> 
> Additionally it solves the need for an #include <alloca.h> on AIX for any usage of the alloca function, by adding the include to globalDefinitions_xlc.hpp

os.cpp / timezone
I leave it to you that it's the correct behaviour
for AIX, for the other platforms it looks good.

os.cpp / print_function_and_library_name()
I don't like assignements in if(), but the fix here
should not change this. Good.

globalDefinitions_xlc.hpp / alloca.h
Good.

globalDefinitions_xlc.hpp / malloc
Having looked at the discussion about this in #14146,
I think this is the solution we want to have here.
I don't think we should harden the code wrt. the fact
that malloc and others can be macros. At least as long
as none of the compilers of the main platforms detects
this (e.g. running in GHA).
Also, I know that Joachim asked IBM to remove the
macro from the header. After all, it worked with xlc16.
So let's fix this here in the _xlc file.

-------------

Marked as reviewed by goetz (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/14283#pullrequestreview-1462844698