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i965/fs: Split out can_coalesce_vars() function.

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Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
This commit is contained in:
Matt Turner 2014-03-27 10:25:57 -07:00
parent 29841fbe20
commit 6499ecafa5
1 changed files with 47 additions and 44 deletions
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91
src/mesa/drivers/dri/i965/brw_fs_register_coalesce.cpp
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@ -65,6 +65,51 @@ is_coalesce_candidate(const fs_inst *inst, const int *virtual_grf_sizes)
return true;
}
static bool
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])) {
/* 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
* things:
* - the start of B's live range must be in A's live range (since we
* already know the two ranges interfere, this is the only remaining
* possibility)
* - the interference isn't of the form we're looking for (where B is
* entirely inside A)
*/
if (live_intervals->end[var_to] > live_intervals->end[var_from])
return false;
int scan_ip = -1;
foreach_list(n, instructions) {
fs_inst *scan_inst = (fs_inst *)n;
scan_ip++;
if (scan_inst->is_control_flow())
return false;
if (scan_ip <= live_intervals->start[var_to])
continue;
if (scan_ip > live_intervals->end[var_to])
break;
if (scan_inst->dst.equals(inst->dst) ||
scan_inst->dst.equals(inst->src[0]))
return false;
}
}
return true;
}
bool
fs_visitor::register_coalesce()
{
@ -87,50 +132,8 @@ fs_visitor::register_coalesce()
int var_from = live_intervals->var_from_reg(&inst->src[0]);
int var_to = live_intervals->var_from_reg(&inst->dst);
if (live_intervals->vars_interfere(var_from, var_to) &&
!inst->dst.equals(inst->src[0])) {
/* 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
* things:
* - the start of B's live range must be in A's live range (since we
* already know the two ranges interfere, this is the only remaining
* possibility)
* - the interference isn't of the form we're looking for (where B is
* entirely inside A)
*/
if (live_intervals->end[var_to] > live_intervals->end[var_from])
continue;
bool overwritten = false;
int scan_ip = -1;
foreach_list(n, &this->instructions) {
fs_inst *scan_inst = (fs_inst *)n;
scan_ip++;
if (scan_inst->is_control_flow()) {
overwritten = true;
break;
}
if (scan_ip <= live_intervals->start[var_to])
continue;
if (scan_ip > live_intervals->end[var_to])
break;
if (scan_inst->dst.equals(inst->dst) ||
scan_inst->dst.equals(inst->src[0])) {
overwritten = true;
break;
}
}
if (overwritten)
continue;
}
if (!can_coalesce_vars(live_intervals, &instructions, inst, var_to, var_from))
continue;
if (reg_from != inst->src[0].reg) {
reg_from = inst->src[0].reg;