fdo-mirrors/mesa
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/mesa/mesa.git synced 2026-05-05 05:18:08 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions 2

nir/repair_ssa: Replace the unreachable check with the phi builder

Browse source 
In a3268599f3, I attempted to fix nir_repair_ssa for unreachable
blocks.  However, that commit missed the possibility that the use is in
a block which, itself, is unreachable.  In this case, we can end up in
an infinite loop trying to replace a def with itself.  Even though a
no-op replacement is a fine operation, it keeps extending the end of the
uses list as we're walking it.  Instead of explicitly checking for the
group of conditions, just check if the phi builder gives us a different
def.  That's guaranteed to be 100% reliable and, while it lacks symmetry
with the is_valid checks, should be more reliable.

Fixes: a3268599 "nir/repair_ssa: Repair dominance for unreachable..."
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
(cherry picked from commit d63162cff0)
This commit is contained in:
Jason Ekstrand 2019-09-09 13:38:37 -05:00 • committed by Dylan Baker
parent 6485fd8362
commit dc7129777f
1 changed files with 44 additions and 35 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

79
src/compiler/nir/nir_repair_ssa.c
View file

@ -103,48 +103,57 @@ repair_ssa_def(nir_ssa_def *def, void *void_state)
nir_foreach_use_safe(src, def) {
nir_block *src_block = get_src_block(src);
if (nir_block_is_unreachable(src_block) ||
!nir_block_dominates(def->parent_instr->block, src_block)) {
nir_ssa_def *block_def =
nir_phi_builder_value_get_block_def(val, src_block);
/* If def was a deref and the use we're looking at is a deref that
* isn't a cast, we need to wrap it in a cast so we don't loose any
* deref information.
*/
if (def->parent_instr->type == nir_instr_type_deref &&
src->parent_instr->type == nir_instr_type_deref &&
nir_instr_as_deref(src->parent_instr)->deref_type != nir_deref_type_cast) {
nir_deref_instr *cast =
nir_deref_instr_create(state->impl->function->shader,
nir_deref_type_cast);
nir_deref_instr *deref = nir_instr_as_deref(def->parent_instr);
cast->mode = deref->mode;
cast->type = deref->type;
cast->parent = nir_src_for_ssa(block_def);
cast->cast.ptr_stride = nir_deref_instr_ptr_as_array_stride(deref);
nir_ssa_dest_init(&cast->instr, &cast->dest,
def->num_components, def->bit_size, NULL);
nir_instr_insert(nir_before_instr(src->parent_instr),
&cast->instr);
block_def = &cast->dest.ssa;
}
nir_instr_rewrite_src(src->parent_instr, src,
nir_src_for_ssa(block_def));
if (src_block == def->parent_instr->block) {
assert(nir_phi_builder_value_get_block_def(val, src_block) == def);
continue;
}
nir_ssa_def *block_def =
nir_phi_builder_value_get_block_def(val, src_block);
if (block_def == def)
continue;
/* If def was a deref and the use we're looking at is a deref that
* isn't a cast, we need to wrap it in a cast so we don't loose any
* deref information.
*/
if (def->parent_instr->type == nir_instr_type_deref &&
src->parent_instr->type == nir_instr_type_deref &&
nir_instr_as_deref(src->parent_instr)->deref_type != nir_deref_type_cast) {
nir_deref_instr *cast =
nir_deref_instr_create(state->impl->function->shader,
nir_deref_type_cast);
nir_deref_instr *deref = nir_instr_as_deref(def->parent_instr);
cast->mode = deref->mode;
cast->type = deref->type;
cast->parent = nir_src_for_ssa(block_def);
cast->cast.ptr_stride = nir_deref_instr_ptr_as_array_stride(deref);
nir_ssa_dest_init(&cast->instr, &cast->dest,
def->num_components, def->bit_size, NULL);
nir_instr_insert(nir_before_instr(src->parent_instr),
&cast->instr);
block_def = &cast->dest.ssa;
}
nir_instr_rewrite_src(src->parent_instr, src, nir_src_for_ssa(block_def));
}
nir_foreach_if_use_safe(src, def) {
nir_block *block_before_if =
nir_cf_node_as_block(nir_cf_node_prev(&src->parent_if->cf_node));
if (nir_block_is_unreachable(block_before_if) ||
!nir_block_dominates(def->parent_instr->block, block_before_if)) {
nir_if_rewrite_condition(src->parent_if, nir_src_for_ssa(
nir_phi_builder_value_get_block_def(val, block_before_if)));
if (block_before_if == def->parent_instr->block) {
assert(nir_phi_builder_value_get_block_def(val, block_before_if) == def);
continue;
}
nir_ssa_def *block_def =
nir_phi_builder_value_get_block_def(val, block_before_if);
if (block_def == def)
continue;
nir_if_rewrite_condition(src->parent_if, nir_src_for_ssa(block_def));
}
return true;