Hi,
Been doing some analysis on some GLSL shader programs with the Mali Offline Compiler, great program btw.
It is however reporting that a clamp (vec3,float,float) is somehow slower for the Mali-Gxx than doing a seperate min/max according the offline compiler.
vec3 clamp_minmax (vec3 val, float minimum, float maximum){ return clamp(val, minimum, maximum);}
vs
vec3 clamp_minmax (vec3 val, float minimum, float maximum){ vec3 rval = min(val, maximum); return max (rval, minimum);}Note that the minimum is a constant 0.0f.
Is this expected and correct for a Mali-Gxx ?
Agree that that instruction packing can cause a difference in cycle count in general. However in this particular case for _b adding the multiply reduces the cycle count (from 2 ->1.25) whereas for _a it increases from (2 ->2.75) according to the tool. So that does make doubt the output of the tool for these GPU's as it does not seem logical that adding a multiply reduces the overall cycle count.
As I am currently mostly using the tool for some estimations I would like to understand if the tool output really reflects the actual performance on these GPU's or if am just looking at some glitch in the tooling.
The absolute numbers for the G series are incorrect (at least for the arithmetic cost) - we'll be fixing this in the next offline compiler release later in the year. The trend direction in terms of is it getting faster or slower should be accurate though, to the best of my knowledge.
Ok , that's enough info for me! Be looking forward to that next release. Thank you for the quick support!