[Bug target/79581] New: VFP4 slower than VFP3 in C-ray
tulipawn at gmail dot com
gcc-bugzilla@gcc.gnu.org
Fri Feb 17 18:40:00 GMT 2017
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)
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