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i965/vec4: Consider sources of non-GRF-dst instructions for dead channels.

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Previously we'd ignore the sources of instructions with non-GRF
destinations when calculating calculating the dead channels. This would
lead to us incorrectly removing the first instruction in this sequence:

   mov vgrf11, ...
   cmp.ne.f0 null, vgrf11, 1.0
   mov vgrf11, ...

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76616
This commit is contained in:
Matt Turner 2014-04-01 14:05:39 -07:00
parent 63d57f3b08
commit 20dee82a75
1 changed files with 8 additions and 12 deletions
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20
src/mesa/drivers/dri/i965/brw_vec4.cpp
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@ -325,6 +325,9 @@ static bool
try_eliminate_instruction(vec4_instruction *inst, int new_writemask,
const struct brw_context *brw)
{
if (inst->has_side_effects())
return false;
if (new_writemask == 0) {
/* Don't dead code eliminate instructions that write to the
* accumulator as a side-effect. Instead just set the destination
@ -387,9 +390,6 @@ vec4_visitor::dead_code_eliminate()
seen_control_flow = inst->is_control_flow() || seen_control_flow;
if (inst->has_side_effects())
continue;
bool inst_writes_flag = false;
if (inst->dst.file != GRF) {
if (inst->dst.is_null() && inst->writes_flag()) {
@ -443,22 +443,18 @@ vec4_visitor::dead_code_eliminate()
node = prev, prev = prev->prev) {
vec4_instruction *scan_inst = (vec4_instruction *)node;
if (scan_inst->has_side_effects())
continue;
if (inst_writes_flag) {
if (scan_inst->dst.is_null() && scan_inst->writes_flag()) {
scan_inst->remove();
progress = true;
continue;
} else if (scan_inst->reads_flag()) {
dead_channels = 0;
break;
}
continue;
} else if (scan_inst->dst.file != GRF) {
continue;
}
if (inst->dst.reg == scan_inst->dst.reg) {
if (inst->dst.file == scan_inst->dst.file &&
inst->dst.reg == scan_inst->dst.reg) {
int new_writemask = scan_inst->dst.writemask & ~dead_channels;
progress = try_eliminate_instruction(scan_inst, new_writemask, brw) ||
@ -466,7 +462,7 @@ vec4_visitor::dead_code_eliminate()
}
for (int i = 0; i < 3; i++) {
if (scan_inst->src[i].file != GRF ||
if (scan_inst->src[i].file != inst->dst.file ||
scan_inst->src[i].reg != inst->dst.reg)
continue;