[PATCH] Enable use of #pragma omp simd reduction(inscan,...) even for GCC10+ in PSTL

[Thomas Rodgers]

Ok for trunk.

> Can you push it into upstream PSTL?

Yes.

Thanks,
Tom.

Jakub Jelinek writes:

> Hi!
>
> Now that GCC supports inclusive/exclusive scans (like ICC 19.0 so far in
> simd constructs only), we can enable it in PSTL as well.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, additionally tested
> with
> #include <execution>
> #include <numeric>
>
> auto
> foo (std::vector<int> &ca, std::vector<int> &co)
> {
>   return std::inclusive_scan(std::execution::unseq, ca.begin(), ca.end(), co.begin());
> }
>
> auto
> bar (std::vector<int> &ca, std::vector<int> &co)
> {
>   return std::exclusive_scan(std::execution::unseq, ca.begin(), ca.end(), co.begin(), 0);
> }
> and verifying with -O2 -fopenmp-simd it is vectorized.  Ok for trunk?
> Can you push it into upstream PSTL?
>
> 2019-06-21  Jakub Jelinek  <jakub@redhat.com>
>
> 	* include/pstl/pstl_config.h (_PSTL_PRAGMA_SIMD_SCAN,
> 	_PSTL_PRAGMA_SIMD_INCLUSIVE_SCAN, _PSTL_PRAGMA_SIMD_EXCLUSIVE_SCAN):
> 	Define to OpenMP 5.0 pragmas even for GCC 10.0+.
> 	(_PSTL_UDS_PRESENT): Define to 1 for GCC 10.0+.
>
> --- libstdc++-v3/include/pstl/pstl_config.h.jj	2019-06-10 18:18:01.551191212 +0200
> +++ libstdc++-v3/include/pstl/pstl_config.h	2019-06-20 17:03:31.466367344 +0200
> @@ -70,7 +70,7 @@
>  #    define _PSTL_PRAGMA_FORCEINLINE
>  #endif
>  
> -#if (__INTEL_COMPILER >= 1900)
> +#if (__INTEL_COMPILER >= 1900) || (_PSTL_GCC_VERSION >= 100000)
>  #    define _PSTL_PRAGMA_SIMD_SCAN(PRM) _PSTL_PRAGMA(omp simd reduction(inscan, PRM))
>  #    define _PSTL_PRAGMA_SIMD_INCLUSIVE_SCAN(PRM) _PSTL_PRAGMA(omp scan inclusive(PRM))
>  #    define _PSTL_PRAGMA_SIMD_EXCLUSIVE_SCAN(PRM) _PSTL_PRAGMA(omp scan exclusive(PRM))
> @@ -100,7 +100,11 @@
>  #    define _PSTL_UDR_PRESENT 0
>  #endif
>  
> -#define _PSTL_UDS_PRESENT (__INTEL_COMPILER >= 1900 && __INTEL_COMPILER_BUILD_DATE >= 20180626)
> +#if ((__INTEL_COMPILER >= 1900 && __INTEL_COMPILER_BUILD_DATE >= 20180626) || _PSTL_GCC_VERSION >= 100000)
> +#    define _PSTL_UDS_PRESENT 1
> +#else
> +#    define _PSTL_UDS_PRESENT 0
> +#endif
>  
>  #if _PSTL_EARLYEXIT_PRESENT
>  #    define _PSTL_PRAGMA_SIMD_EARLYEXIT _PSTL_PRAGMA(omp simd early_exit)
>
> 	Jakub