RFR: JDK-8308288: Fix xlc17 clang warnings in shared code [v2]

[Thomas Stuefe]

On Thu, 25 May 2023 18:18:43 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> src/hotspot/share/utilities/globalDefinitions_xlc.hpp line 47:
>> 
>>> 45:   #undef malloc
>>> 46:   extern void *malloc(size_t) asm("vec_malloc");
>>> 47: #endif
>> 
>> Wow!  And I don't mean that in a good way.  I'm not questioning whether this is correct, just commenting
>> on how crazy it seems that such a thing might be needed.
>
> The crazy thing is that `malloc` is defined! That means all places where we use the term malloc are getting replaced without such a workaround. (E.g. for log tags.)

So, we do this only for malloc? Not for calloc, posix_memalign, realloc etc? What about free? 

As ugly as defining malloc is (and I remember QADRT), I hesitate about removing that define.

Removing that define and hard-coding it here assumes 1) our replacement is equivalent (ok, easy to check) 2) it will always be equivalent in future AIX versions 3) pointers it returns work with the unchanged free() and realloc() the system provides, and will always do so.

I don't know... I would not do this just to get rid of a warning.

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PR Review Comment: https://git.openjdk.org/jdk/pull/14146#discussion_r1207078176