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nir: Replace nir_ssa_def->live_index with nir_instr->index.

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live_index had two things going on: 0 meant the instr was an undef and
always dead, and otherwise ssa defs had increasing numbers by instruction
order.  We already have a field in the instruction for storing instruction
order, and ssa defs don't need that number to be contiguous (if you want a
compact per-ssa-def number, use ssa->index after reindexing).

We don't use ssa->index for this, because reindexing those would change
nir_print, and that would be rude to people trying to track what's
happening in optimization passes.

This openend up a hole in nir_ssa_def, so we move nir_ssa_def->index
toward the end to shrink the struct from 64 bytes to 56.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3395>
This commit is contained in:
Eric Anholt
2020-09-29 15:44:57 -07:00
parent b6cb184e86
commit 2f5d18403a
4 changed files with 33 additions and 39 deletions
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29
src/compiler/nir/nir_from_ssa.c
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@@ -44,17 +44,33 @@ struct from_ssa_state {
bool progress;
};
/* Returns if def @a comes after def @b.
*
* We treat SSA undefs as always coming before other instruction types.
*/
static bool
def_after(nir_ssa_def *a, nir_ssa_def *b)
{
if (a->parent_instr->type == nir_instr_type_ssa_undef)
return false;
if (b->parent_instr->type == nir_instr_type_ssa_undef)
return true;
return a->parent_instr->index > b->parent_instr->index;
}
/* Returns true if a dominates b */
static bool
ssa_def_dominates(nir_ssa_def *a, nir_ssa_def *b)
{
if (a->live_index == 0) {
if (a->parent_instr->type == nir_instr_type_ssa_undef) {
/* SSA undefs always dominate */
return true;
} else if (b->live_index < a->live_index) {
} if (def_after(a, b)) {
return false;
} else if (a->parent_instr->block == b->parent_instr->block) {
return a->live_index <= b->live_index;
return def_after(b, a);
} else {
return nir_block_dominates(a->parent_instr->block,
b->parent_instr->block);
@@ -157,7 +173,7 @@ merge_merge_sets(merge_set *a, merge_set *b)
merge_node *b_node = exec_node_data(merge_node, bn, node);
if (exec_node_is_tail_sentinel(an) ||
a_node->def->live_index > b_node->def->live_index) {
def_after(a_node->def, b_node->def)) {
struct exec_node *next = bn->next;
exec_node_remove(bn);
exec_node_insert_node_before(an, bn);
@@ -202,7 +218,7 @@ merge_sets_interfere(merge_set *a, merge_set *b)
merge_node *a_node = exec_node_data(merge_node, an, node);
merge_node *b_node = exec_node_data(merge_node, bn, node);
if (a_node->def->live_index <= b_node->def->live_index) {
if (def_after(b_node->def, a_node->def)) {
current = a_node;
an = an->next;
} else {
@@ -785,7 +801,8 @@ nir_convert_from_ssa_impl(nir_function_impl *impl, bool phi_webs_only)
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
nir_metadata_require(impl, nir_metadata_live_ssa_defs |
nir_metadata_require(impl, nir_metadata_instr_index |
nir_metadata_live_ssa_defs |
nir_metadata_dominance);
nir_foreach_block(block, impl) {