[Bug target/79581] New: VFP4 slower than VFP3 in C-ray

["tulipawn at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79581

            Bug ID: 79581
           Summary: VFP4 slower than VFP3 in C-ray
           Product: gcc
           Version: 7.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tulipawn at gmail dot com
  Target Milestone: ---

Created attachment 40762
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40762&action=edit
preprocessed source

$ gcc -marm -Ofast -mcpu=cortex-a5 -mfpu=vfpv3 c-ray-mt.i -lm -lpthread 

$ ./a.out -t 32 -s 160x120 -r 8 -i sphfract -o output.ppm ; done

Rendering took: 2 seconds (2393 milliseconds)

$ gcc -marm -Ofast -mcpu=cortex-a5 -mfpu=vfpv4 c-ray-mt.i -lm -lpthread

$ ./a.out -t 32 -s 160x120 -r 8 -i sphfract -o output.ppm ; done

Rendering took: 2 seconds (2494 milliseconds)

This defect dates back to gcc 4.9 (or earlier) but at least gcc 7 provides a
big speedup in vfvp4 code. (roughly 2500 now vs 2700 previously)