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

[Kim Barrett]

On Tue, 2 Apr 2024 16:14:12 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_gcc.hpp the compiler is much more nagging about ill formatted printf
>
> Joachim Kern has updated the pull request incrementally with one additional commit since the last revision:
> 
>   version check not needed anymore

Changes requested by kbarrett (Reviewer).

src/hotspot/share/utilities/byteswap.hpp line 2:

> 1: /*
> 2:  * Copyright (c) 2023, Google and/or its affiliates. All rights reserved.

Don't drop the creation year.

src/hotspot/share/utilities/globalDefinitions_gcc.hpp line 36:

> 34: #if defined(_AIX)
> 35: #include <alloca.h>
> 36: #endif

I would much rather see this include added in the few places it was actually needed, rather than being
added here.

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PR Review: https://git.openjdk.org/jdk/pull/18536#pullrequestreview-1989864573
PR Review Comment: https://git.openjdk.org/jdk/pull/18536#discussion_r1558124034
PR Review Comment: https://git.openjdk.org/jdk/pull/18536#discussion_r1558172309