fdo-mirrors/mesa
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/mesa/mesa.git synced 2026-04-23 11:40:39 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions 4

i965/vec4: Optimize sqrt+inv into rsq.

Browse source 
Transform

   sqrt a, b
   rcp  c, a

into

   sqrt a, b
   rsq  c, b

In most cases the sqrt's result is still used, so the improvement here
is that we've broken a dependency between these instructions. Leads to
80 fewer INV instructions and 80 more RSQ.

Occasionally the sqrt's result is no longer used, leading to:

instructions in affected programs:     5005 -> 4949 (-1.12%)

Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
This commit is contained in:
Matt Turner 2014-09-27 10:34:27 -07:00
parent 189ac07764
commit b52126b44f
1 changed files with 11 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

11
src/mesa/drivers/dri/i965/brw_vec4.cpp
View file

@ -731,6 +731,17 @@ vec4_visitor::opt_algebraic()
progress = true;
}
break;
case SHADER_OPCODE_RCP: {
vec4_instruction *prev = (vec4_instruction *)inst->prev;
if (prev->opcode == SHADER_OPCODE_SQRT) {
if (inst->src[0].equals(src_reg(prev->dst))) {
inst->opcode = SHADER_OPCODE_RSQ;
inst->src[0] = prev->src[0];
progress = true;
}
}
break;
}
default:
break;
}