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i965/fs: Optimize ssbo stores 

Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Write groups of enabled components together.

Signed-off-by: Kristian Høgsberg Kristensen <krh@bitplanet.net>
This commit is contained in:
Kristian Høgsberg Kristensen 2015-10-21 23:43:34 -07:00
parent feff21d1a6
commit 0cb7d7b4b7
1 changed files with 25 additions and 30 deletions
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55
src/mesa/drivers/dri/i965/brw_fs_nir.cpp
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@ -1759,45 +1759,40 @@ fs_visitor::nir_emit_intrinsic(const fs_builder &bld, nir_intrinsic_instr *instr
nir->info.num_ssbos - 1);
}
/* Offset */
fs_reg offset_reg = vgrf(glsl_type::uint_type);
unsigned const_offset_bytes = 0;
if (has_indirect) {
bld.MOV(offset_reg, get_nir_src(instr->src[2]));
} else {
const_offset_bytes = instr->const_index[0];
bld.MOV(offset_reg, fs_reg(const_offset_bytes));
}
/* Value */
fs_reg val_reg = get_nir_src(instr->src[0]);
/* Writemask */
unsigned writemask = instr->const_index[1];
/* Write each component present in the writemask */
unsigned skipped_channels = 0;
for (int i = 0; i < instr->num_components; i++) {
int component_mask = 1 << i;
if (writemask & component_mask) {
if (skipped_channels) {
if (!has_indirect) {
const_offset_bytes += 4 * skipped_channels;
bld.MOV(offset_reg, fs_reg(const_offset_bytes));
} else {
bld.ADD(offset_reg, offset_reg,
brw_imm_ud(4 * skipped_channels));
}
skipped_channels = 0;
}
/* Combine groups of consecutive enabled channels in one write
* message. We use ffs to find the first enabled channel and then ffs on
* the bit-inverse, down-shifted writemask to determine the length of
* the block of enabled bits.
*/
while (writemask) {
unsigned first_component = ffs(writemask) - 1;
unsigned length = ffs(~(writemask >> first_component)) - 1;
fs_reg offset_reg;
emit_untyped_write(bld, surf_index, offset_reg,
offset(val_reg, bld, i),
1 /* dims */, 1 /* size */,
BRW_PREDICATE_NONE);
if (!has_indirect) {
offset_reg = fs_reg(instr->const_index[0] + 4 * first_component);
} else {
offset_reg = vgrf(glsl_type::uint_type);
bld.ADD(offset_reg,
retype(get_nir_src(instr->src[2]), BRW_REGISTER_TYPE_UD),
fs_reg(4 * first_component));
}
skipped_channels++;
emit_untyped_write(bld, surf_index, offset_reg,
offset(val_reg, bld, first_component),
1 /* dims */, length,
BRW_PREDICATE_NONE);
/* Clear the bits in the writemask that we just wrote, then try
* again to see if more channels are left.
*/
writemask &= (15 << (first_component + length));
}
break;
}