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i965/fs: Recognize nop-MOV instructions early.

Browse source 
And avoid rewriting other instructions unnecessarily. Removes a few
self-moves we weren't able to handle because they were components of a
large VGRF.

instructions in affected programs:     830 -> 826 (-0.48%)

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Matt Turner 2014-04-15 18:15:59 -07:00
parent ef6127ff69
commit a975b2f55c
1 changed files with 17 additions and 3 deletions
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20
src/mesa/drivers/dri/i965/brw_fs_register_coalesce.cpp
View file

@ -43,6 +43,16 @@
#include "brw_fs.h"
#include "brw_fs_live_variables.h"
static bool
is_nop_mov(const fs_inst *inst)
{
if (inst->opcode == BRW_OPCODE_MOV) {
return inst->dst.equals(inst->src[0]);
}
return false;
}
static bool
is_coalesce_candidate(const fs_inst *inst, const int *virtual_grf_sizes)
{
@ -70,9 +80,7 @@ can_coalesce_vars(brw::fs_live_variables *live_intervals,
const exec_list *instructions, const fs_inst *inst,
int var_to, int var_from)
{
if (live_intervals->vars_interfere(var_from, var_to) &&
!inst->dst.equals(inst->src[0])) {
if (live_intervals->vars_interfere(var_from, var_to)) {
/* We know that the live ranges of A (var_from) and B (var_to)
* interfere because of the ->vars_interfere() call above. If the end
* of B's live range is after the end of A's range, then we know two
@ -131,6 +139,12 @@ fs_visitor::register_coalesce()
if (!is_coalesce_candidate(inst, virtual_grf_sizes))
continue;
if (is_nop_mov(inst)) {
inst->opcode = BRW_OPCODE_NOP;
progress = true;
continue;
}
if (reg_from != inst->src[0].reg) {
reg_from = inst->src[0].reg;