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i965/fs: Consider type mismatches in saturate propagation.

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NIR considers bcsel to produce and consume unsigned types, leading to
SEL instructions operating on unsigned types when the data is really
floating-point. Previous to this patch, saturate propagation would
happily transform

   (+f0) sel      g20:UD, g30:UD, g40:UD
         mov.sat  g50:F,  g20:F

into

   (+f0) sel.sat  g20:UD, g30:UD, g40:UD
         mov      g50:F,  g20:F

But since the meaning of .sat is dependent on the type of the
destination register, this is not valid.

Instead, allow saturate propagation to change the types of dest/source
on instructions that are simply copying data in order to propagate the
saturate modifier.

Fixes bad code gen in 158 programs.

Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>
This commit is contained in:
Matt Turner
2015-10-14 02:23:25 -07:00
parent 9e17c36b8b
commit 35a2d259f2
1 changed files with 12 additions and 3 deletions
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src/mesa/drivers/dri/i965/brw_fs_saturate_propagation.cpp
+12 -3
View File
@@ -52,11 +52,12 @@ opt_saturate_propagation_local(fs_visitor *v, bblock_t *block)
ip--;
if (inst->opcode != BRW_OPCODE_MOV ||
!inst->saturate ||
inst->dst.file != GRF ||
inst->dst.type != inst->src[0].type ||
inst->src[0].file != GRF ||
inst->src[0].abs ||
inst->src[0].negate ||
!inst->saturate)
inst->src[0].negate)
continue;
int src_var = v->live_intervals->var_from_reg(inst->src[0]);
@@ -65,7 +66,9 @@ opt_saturate_propagation_local(fs_visitor *v, bblock_t *block)
bool interfered = false;
foreach_inst_in_block_reverse_starting_from(fs_inst, scan_inst, inst, block) {
if (scan_inst->overwrites_reg(inst->src[0])) {
if (scan_inst->is_partial_write())
if (scan_inst->is_partial_write() ||
(scan_inst->dst.type != inst->dst.type &&
!scan_inst->can_change_types()))
break;
if (scan_inst->saturate) {
@@ -73,6 +76,12 @@ opt_saturate_propagation_local(fs_visitor *v, bblock_t *block)
progress = true;
} else if (src_end_ip <= ip || inst->dst.equals(inst->src[0])) {
if (scan_inst->can_do_saturate()) {
if (scan_inst->dst.type != inst->dst.type) {
scan_inst->dst.type = inst->dst.type;
for (int i = 0; i < scan_inst->sources; i++) {
scan_inst->src[i].type = inst->dst.type;
}
}
scan_inst->saturate = true;
inst->saturate = false;
progress = true;