RFR: 8338303: Linux ppc64le with toolchain clang - detection failure in early JVM startup

[Matthias Baesken]

On Fri, 24 Jan 2025 09:09:15 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

> When building on Linux ppc64le with the clang toolchain, the new JVM fails already in the build process with an error/crash :
> 
> 
> # SIGILL (0x4) at pc=0x000079198fae03ac, pid=2922849, tid=2923410
> #
> # Problematic frame:
> # v ~BufferBlob::detect_cpu_features 0x000079198fae03ac
> 
> 
> It was noticed the clang build on Linux ppc64le missed some important compile flags, especially  -DABI_ELFv2 (compared to gcc build).

Hi Erik and Martin , thanks for the reviews !

I also noticed we set   `-fstack-protector`    only for Linux/gcc  but not for clang.  Probably we should change this (but in a separate PR).  
See
https://github.com/openjdk/jdk/blob/909cef5198e91f56e4c76c2cf86048583791f3ab/make/autoconf/flags-cflags.m4#L526
(seems we set it already for AIX/clang)

The compile flag  ` -D_REENTRANT`  is also only set for gcc not clang in the JVM compilation units.  Not sure if we need it.
See https://github.com/openjdk/jdk/blob/909cef5198e91f56e4c76c2cf86048583791f3ab/make/autoconf/flags-cflags.m4#L497 .

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PR Comment: https://git.openjdk.org/jdk/pull/23292#issuecomment-2612785631