RFR: 8319577: x86_64 AVX2 intrinsics for Arrays.sort methods (int, float arrays) [v8]

[Magnus Ihse Bursie]

On Tue, 5 Dec 2023 17:26:06 GMT, Srinivas Vamsi Parasa <duke at openjdk.org> wrote:

>> That sounds weird. You can't check for if compiler options should be enabled or not inside source code files.
>> 
>> Are you saying that when compiling with GCC 6, it will just silently ignore `-std=c++17`? I'd have assumed that it printed a warning or error about an unknown or invalid option, if C++17 is not supported.
>
> Hi Magnus (@magicus),
>  
>> Are you saying that when compiling with GCC 6, it will just silently ignore `-std=c++17`? I'd have assumed that it printed a warning or error about an unknown or invalid option, if C++17 is not supported.
> 
> The GCC complier for versions 6 (and even 5) silently ignores the flag `-std=c++17`. It does not print any warning or error. I tested it with a toy C++ program and also by building OpenJDK using GCC 6. 
> 
>> You can't check for if compiler options should be enabled or not inside source code files.
> 
>  what I meant was, there are #ifdef guards using predefined macros in the C++ source code to check for GCC version and make the simdsort code available for compilation or not based on the GCC version
> 
> 
> // src/java.base/linux/native/libsimdsort/simdsort-support.hpp
> #if defined(_LP64) && (defined(__GNUC__) && ((__GNUC__ > 7) || ((__GNUC__ == 7) && (__GNUC_MINOR__ >= 5))))
>         #define __SIMDSORT_SUPPORTED_LINUX
> #endif
> 
> 
> 
> //src/java.base/linux/native/libsimdsort/avx2-linux-qsort.cpp
> #include "simdsort-support.hpp"
> #ifdef __SIMDSORT_SUPPORTED_LINUX
>             <simdsort functions>
> #endif

Okay, then I guess I am fine with this.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16534#discussion_r1417170882