RFR: JDK-8329257: AIX: Switch HOTSPOT_TOOLCHAIN_TYPE from xlc to gcc

[Joachim Kern]

On Thu, 28 Mar 2024 16:50:20 GMT, Joachim Kern <jkern at openjdk.org> wrote:

> As of [JDK-8325880](https://bugs.openjdk.org/browse/JDK-8325880), building the JDK requires version 17 of IBM Open XL C/C++ (xlc). This is in effect clang by another name, and it uses the clang toolchain in the JDK build. Thus the old xlc toolchain was removed by [JDK-8327701](https://bugs.openjdk.org/browse/JDK-8327701).
> Now we also switch the HOTSPOT_TOOLCHAIN_TYPE from xlc to gcc, removing the last xlc rudiment.
> This means merging the AIX specific content of utilities/globalDefinitions_xlc.hpp and utilities/compilerWarnings_xlc.hpp into the corresponding gcc files on the on side and removing the defined(TARGET_COMPILER_xlc) blocks in the code, because the defined(TARGET_COMPILER_gcc) blocks work out of the box for the new AIX compiler.
> The rest of the changes are needed because of using utilities/compilerWarnings_xlc.hpp the compiler is much more nagging about ill formatted printf

src/hotspot/share/utilities/globalDefinitions_gcc.hpp line 83:

> 81:   #error "xlc version not supported, macro __open_xl_version__ not found"
> 82: #endif
> 83: #endif // AIX

This `#ifdef _AIX` might be obsolete, because configure will throw a warning if the compiler has a lower version, but it's only a warning.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18536#discussion_r1543307859