RFR: 8329257: AIX: Switch HOTSPOT_TOOLCHAIN_TYPE from xlc to gcc [v3]

[Magnus Ihse Bursie]

On Tue, 16 Apr 2024 08:49:02 GMT, Joachim Kern <jkern at openjdk.org> wrote:

>> Should also remove the `#pragma alloca` in os_aix.cpp.
>
> We can not use `#include <alloca.h>` in all files which use `alloca`, because windows does not know this header. Maybe we can use `#include <alloca.h>` unconditionally in globalDefinitions_gcc.hpp, if windows will never use this file. @kimbarrett What do you say?

That was kind of where the discussion started, and which Kim did not like. If I read him correctly, his suggestion was instead to place:

#if defined(_AIX)
#include <alloca.h>
#endif

in the files where `alloca` is needed on AIX.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18536#discussion_r1567026294