RFR: 8325880: Require minimum Open XL C/C++ version 17.1.1

[Joachim Kern]

On Thu, 15 Feb 2024 10:40:53 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

> What does this mean? That you are not using xlc at all? Or is it clang but still with an xlc frontend, so all xlc flags etc need to stay?


The `xlc` toolchain is for the compiler versions up to 16 (xlclang++); the `clang` toolchain is for the compiler versions 17 (ibm-clang++_r) and higher. For the 17 Compiler the frontend is `clang`-ish and we are using the `clang` flags instead of the `xlc` flags.
`toolchain.m4` decides on the basis of the found compiler which toolchain to use as default.

# On AIX the default toolchain depends on the installed (found) compiler
  #   xlclang++     -> xlc toolchain
  #   ibm-clang++_r -> clang toolchain
  # The compiler is searched on the PATH and TOOLCHAIN_PATH
  # xlclang++ has precedence over ibm-clang++_r if both are installed

So, if we set the minimum compiler level for AIX to 17, we can remove the xlc toolchain at all. 
We cannot remove every reference to xlc, because at least some headers we still use the xlc version (globalDefinitions_xlc.hpp)

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PR Comment: https://git.openjdk.org/jdk/pull/17857#issuecomment-1945873440