The LLVM Fortran Performance Is Beating Out GCC But Losing To PGI

[phoronix]

Phoronix: The LLVM Fortran Performance Is Beating Out GCC But Losing To PGI

At last month's EuroLLVM conference, NVIDIA provided an update on the "Flang" project for offering first-rate Fortran support within LLVM, including some initial benchmark figures...

http://www.phoronix.com/scan.php?page=news_item&px=LLVM-f18-Fortran-Performance-19

[celrod]

Those benchmarks are using Flang, which is using PGI's open source front end + LLVM.
f18 is going to replace the pgi frontend with much more modern code. Will be interesting to see how it does in performance once it can start compiling programs!

Anyone have a time frame (or ballpark) on that?

[hubicka]

What optimization flags was used? In other variants of the slides, like http://llvm.org/devmtg/2018-04/slide...langUpdate.pdf it seems that flang used -march=native while GCC did not. This compares AVX vectorized code to SSE that is, of course, important factor.

Another aspect is that PGI comes with math library that outperforms older glibc implementations. New glibc is needed and GCC configured to use the vector math.