Mesa (master): i965/fs: Patch the instruction generating discards; don' t use CMP.Z.
Kenneth Graunke
kwg at kemper.freedesktop.org
Fri Feb 27 19:38:39 UTC 2015
Module: Mesa
Branch: master
Commit: ea696be5ac097af621f10858d925a343a838be7a
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=ea696be5ac097af621f10858d925a343a838be7a
Author: Kenneth Graunke <kenneth at whitecape.org>
Date: Wed Feb 25 16:08:14 2015 -0800
i965/fs: Patch the instruction generating discards; don't use CMP.Z.
CMP.Z doesn't work on Gen4-5 because the boolean isn't guaranteed to be
0 or 0xFFFFFFFF - only the low bit is defined.
We can call emit_bool_to_cond_code to generate the condition in f0.0;
the last instruction will generate the flag value. We can patch it to
use f0.1, and negate the condition.
Fixes discard tests on Gen4-5.
Haswell shader-db stats:
total instructions in shared programs: 5770279 -> 5769112 (-0.02%)
instructions in affected programs: 64342 -> 63175 (-1.81%)
helped: 1069
Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
Reviewed-by: Matt Turner <mattst88 at gmail.com>
---
src/mesa/drivers/dri/i965/brw_fs_visitor.cpp | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
index 13a3bf2..7a697e8 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
@@ -2422,8 +2422,9 @@ fs_visitor::visit(ir_discard *ir)
*/
fs_inst *cmp;
if (ir->condition) {
- ir->condition->accept(this);
- cmp = emit(CMP(reg_null_f, this->result, fs_reg(0), BRW_CONDITIONAL_Z));
+ emit_bool_to_cond_code(ir->condition);
+ cmp = (fs_inst *) this->instructions.get_tail();
+ cmp->conditional_mod = brw_negate_cmod(cmp->conditional_mod);
} else {
fs_reg some_reg = fs_reg(retype(brw_vec8_grf(0, 0),
BRW_REGISTER_TYPE_UW));
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