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i965/fs: Perform CSE on CMP(N) instructions.

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Optimizes

      cmp.ge.f0(8)  null     g45<8,8,1>F  0F
(+f0) sel(8)        g50<1>F  g40<8,8,1>F  g10<8,8,1>F
      cmp.ge.f0(8)  null     g45<8,8,1>F  0F
(+f0) sel(8)        g51<1>F  g41<8,8,1>F  g11<8,8,1>F
      cmp.ge.f0(8)  null     g45<8,8,1>F  0F
(+f0) sel(8)        g52<1>F  g42<8,8,1>F  g12<8,8,1>F
      cmp.ge.f0(8)  null     g45<8,8,1>F  0F
(+f0) sel(8)        g53<1>F  g43<8,8,1>F  g13<8,8,1>F

into

      cmp.ge.f0(8)  null     g45<8,8,1>F  0F
(+f0) sel(8)        g50<1>F  g40<8,8,1>F  g10<8,8,1>F
(+f0) sel(8)        g51<1>F  g41<8,8,1>F  g11<8,8,1>F
(+f0) sel(8)        g52<1>F  g42<8,8,1>F  g12<8,8,1>F
(+f0) sel(8)        g53<1>F  g43<8,8,1>F  g13<8,8,1>F

total instructions in shared programs: 1644938 -> 1638181 (-0.41%)
instructions in affected programs:     574955 -> 568198 (-1.18%)

Two more 16-wide programs (in L4D2). Some large (-9%) decreases in
instruction count in some of Valve's Source Engine games. No
regressions.

Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Paul Berry <stereotype441@gmail.com>
This commit is contained in:
Matt Turner 2013-10-20 11:38:17 -07:00
parent 219b43c612
commit b16b3c8703
1 changed files with 29 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

39
src/mesa/drivers/dri/i965/brw_fs_cse.cpp
View file

@ -54,6 +54,8 @@ is_expression(const fs_inst *const inst)
case BRW_OPCODE_SHR:
case BRW_OPCODE_SHL:
case BRW_OPCODE_ASR:
case BRW_OPCODE_CMP:
case BRW_OPCODE_CMPN:
case BRW_OPCODE_ADD:
case BRW_OPCODE_MUL:
case BRW_OPCODE_FRC:
@ -102,6 +104,18 @@ operands_match(enum opcode op, fs_reg *xs, fs_reg *ys)
}
}
static bool
instructions_match(fs_inst *a, fs_inst *b)
{
return a->opcode == b->opcode &&
a->saturate == b->saturate &&
a->predicate == b->predicate &&
a->predicate_inverse == b->predicate_inverse &&
a->conditional_mod == b->conditional_mod &&
a->dst.type == b->dst.type &&
operands_match(a->opcode, a->src, b->src);
}
bool
fs_visitor::opt_cse_local(bblock_t *block, exec_list *aeb)
{
@ -115,11 +129,7 @@ fs_visitor::opt_cse_local(bblock_t *block, exec_list *aeb)
inst = (fs_inst *) inst->next) {
/* Skip some cases. */
if (is_expression(inst) &&
!inst->predicate &&
!inst->is_partial_write() &&
!inst->conditional_mod &&
inst->dst.file != HW_REG)
if (is_expression(inst) && !inst->is_partial_write())
{
bool found = false;
@ -128,11 +138,7 @@ fs_visitor::opt_cse_local(bblock_t *block, exec_list *aeb)
entry = (aeb_entry *) entry_node;
/* Match current instruction's expression against those in AEB. */
if (inst->opcode == entry->generator->opcode &&
inst->saturate == entry->generator->saturate &&
inst->dst.type == entry->generator->dst.type &&
operands_match(inst->opcode, entry->generator->src, inst->src)) {
if (instructions_match(inst, entry->generator)) {
found = true;
progress = true;
break;
@ -208,6 +214,19 @@ fs_visitor::opt_cse_local(bblock_t *block, exec_list *aeb)
foreach_list_safe(entry_node, aeb) {
aeb_entry *entry = (aeb_entry *)entry_node;
/* Kill all AEB entries that write a different value to or read from
* the flag register if we just wrote it.
*/
if (inst->writes_flag()) {
if (entry->generator->reads_flag() ||
(entry->generator->writes_flag() &&
!instructions_match(inst, entry->generator))) {
entry->remove();
ralloc_free(entry);
continue;
}
}
for (int i = 0; i < 3; i++) {
fs_reg *src_reg = &entry->generator->src[i];