Mesa (master): i965/fs: Optimize sqrt+inv into rsq.
Matt Turner
mattst88 at kemper.freedesktop.org
Wed Oct 1 00:10:02 UTC 2014
Module: Mesa
Branch: master
Commit: 94b68109fbe1cb60cc23a4c5a319039ada81ea81
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=94b68109fbe1cb60cc23a4c5a319039ada81ea81
Author: Matt Turner <mattst88 at gmail.com>
Date: Sat Sep 27 10:34:56 2014 -0700
i965/fs: Optimize sqrt+inv into rsq.
Transform
sqrt a, b
rcp c, a
into
sqrt a, b
rsq c, b
The improvement here is that we've broken a dependency between these
instructions. Leads to 330 fewer INV instructions and 330 more RSQ.
Reviewed-by: Anuj Phogat <anuj.phogat at gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>
---
src/mesa/drivers/dri/i965/brw_fs.cpp | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index ab4ee34..19e9cb9 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -2334,6 +2334,17 @@ fs_visitor::opt_algebraic()
}
}
break;
+ case SHADER_OPCODE_RCP: {
+ fs_inst *prev = (fs_inst *)inst->prev;
+ if (prev->opcode == SHADER_OPCODE_SQRT) {
+ if (inst->src[0].equals(prev->dst)) {
+ inst->opcode = SHADER_OPCODE_RSQ;
+ inst->src[0] = prev->src[0];
+ progress = true;
+ }
+ }
+ break;
+ }
default:
break;
}
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