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i965/fs: Allow flipping cond mod for negated arguments.

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This allows us to apply the optimization in cases where the CMP's
argument is negated, by flipping the conditional mod. For example, it
allows us to optimize this:

   add(8)       temp   a      b
   cmp.l.f0(8)  null   -temp  0.0

into

   add.g.f0(8)  temp   a      b

total instructions in shared programs: 5958360 -> 5955701 (-0.04%)
instructions in affected programs:     466880 -> 464221 (-0.57%)
GAINED:                                0
LOST:                                  1

Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Matt Turner
2014-12-30 12:18:57 -08:00
parent d6317beb46
commit 9a3a294224
2 changed files with 39 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/mesa/drivers/dri/i965/brw_fs_cmod_propagation.cpp
+6 -3
View File
@@ -62,7 +62,6 @@ opt_cmod_propagation_local(fs_visitor *v, bblock_t *block)
!inst->dst.is_null() ||
inst->src[0].file != GRF ||
inst->src[0].abs ||
inst->src[0].negate ||
!inst->src[1].is_zero())
continue;
@@ -74,10 +73,14 @@ opt_cmod_propagation_local(fs_visitor *v, bblock_t *block)
scan_inst->dst.reg_offset != inst->src[0].reg_offset)
break;
enum brw_conditional_mod cond =
inst->src[0].negate ? brw_swap_cmod(inst->conditional_mod)
: inst->conditional_mod;
if (scan_inst->can_do_cmod() &&
((!read_flag && scan_inst->conditional_mod == BRW_CONDITIONAL_NONE) ||
scan_inst->conditional_mod == inst->conditional_mod)) {
scan_inst->conditional_mod = inst->conditional_mod;
scan_inst->conditional_mod == cond)) {
scan_inst->conditional_mod = cond;
inst->remove(block);
progress = true;
}
src/mesa/drivers/dri/i965/test_fs_cmod_propagation.cpp
+33
View File
@@ -350,3 +350,36 @@ TEST_F(cmod_propagation_test, intervening_flag_read_same_value)
EXPECT_EQ(BRW_OPCODE_SEL, instruction(block0, 1)->opcode);
EXPECT_EQ(BRW_PREDICATE_NORMAL, instruction(block0, 1)->predicate);
}
TEST_F(cmod_propagation_test, negate)
{
fs_reg dest = v->vgrf(glsl_type::float_type);
fs_reg src0 = v->vgrf(glsl_type::float_type);
fs_reg src1 = v->vgrf(glsl_type::float_type);
fs_reg zero(0.0f);
v->emit(BRW_OPCODE_ADD, dest, src0, src1);
dest.negate = true;
v->emit(BRW_OPCODE_CMP, v->reg_null_f, dest, zero)
->conditional_mod = BRW_CONDITIONAL_GE;
/* = Before =
*
* 0: add(8) dest src0 src1
* 1: cmp.ge.f0(8) null -dest 0.0f
*
* = After =
* 0: add.le.f0(8) dest src0 src1
*/
v->calculate_cfg();
bblock_t *block0 = v->cfg->blocks[0];
EXPECT_EQ(0, block0->start_ip);
EXPECT_EQ(1, block0->end_ip);
EXPECT_TRUE(cmod_propagation(v));
EXPECT_EQ(0, block0->start_ip);
EXPECT_EQ(0, block0->end_ip);
EXPECT_EQ(BRW_OPCODE_ADD, instruction(block0, 0)->opcode);
EXPECT_EQ(BRW_CONDITIONAL_LE, instruction(block0, 0)->conditional_mod);
}