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nir/opt_remove_phis: use nir_shader_phi_pass

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Reviewed-by: Konstantin Seurer <konstantin.seurer@gmail.com>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33672>
This commit is contained in:
Georg Lehmann
2025-02-22 13:14:20 +01:00
committed by Marge Bot
parent e4f0de89a5
commit 940e87f225
1 changed files with 53 additions and 88 deletions
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src/compiler/nir/nir_opt_remove_phis.c
+53 -88
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@@ -89,69 +89,66 @@ can_rematerialize_phi_src(nir_block *imm_dom, nir_def *def)
*/
static bool
remove_phis_block(nir_block *block, nir_builder *b)
remove_phis_instr(nir_builder *b, nir_phi_instr *phi, void *unused)
{
bool progress = false;
nir_block *block = phi->instr.block;
nir_def *def = NULL;
bool needs_remat = false;
nir_foreach_phi_safe(phi, block) {
nir_def *def = NULL;
bool srcs_same = true;
bool needs_remat = false;
nir_foreach_phi_src(src, phi) {
/* For phi nodes at the beginning of loops, we may encounter some
* sources from backedges that point back to the destination of the
* same phi, i.e. something like:
*
* a = phi(a, b, ...)
*
* We can safely ignore these sources, since if all of the normal
* sources point to the same definition, then that definition must
* still dominate the phi node, and the phi will still always take
* the value of that definition.
*/
if (src->src.ssa == &phi->def)
continue;
/* Ignore undef sources. */
if (nir_src_is_undef(src->src))
continue;
if (def == NULL) {
def = src->src.ssa;
if (!nir_block_dominates(def->parent_instr->block, block->imm_dom)) {
if (!can_rematerialize_phi_src(block->imm_dom, def)) {
srcs_same = false;
break;
}
needs_remat = true;
}
} else if (!phi_srcs_equal(src->src.ssa, def)) {
srcs_same = false;
break;
}
}
if (!srcs_same)
nir_foreach_phi_src(src, phi) {
/* For phi nodes at the beginning of loops, we may encounter some
* sources from backedges that point back to the destination of the
* same phi, i.e. something like:
*
* a = phi(a, b, ...)
*
* We can safely ignore these sources, since if all of the normal
* sources point to the same definition, then that definition must
* still dominate the phi node, and the phi will still always take
* the value of that definition.
*/
if (src->src.ssa == &phi->def)
continue;
if (!def) {
/* In this case, the phi had no non undef sources. So turn it into an undef. */
b->cursor = nir_after_phis(block);
def = nir_undef(b, phi->def.num_components, phi->def.bit_size);
} else if (needs_remat) {
b->cursor = nir_after_block_before_jump(block->imm_dom);
nir_instr *remat = nir_instr_clone(b->shader, def->parent_instr);
nir_builder_instr_insert(b, remat);
def = nir_instr_def(remat);
/* Ignore undef sources. */
if (nir_src_is_undef(src->src))
continue;
if (def == NULL) {
def = src->src.ssa;
if (!nir_block_dominates(def->parent_instr->block, block->imm_dom)) {
if (!can_rematerialize_phi_src(block->imm_dom, def))
return false;
needs_remat = true;
}
} else if (!phi_srcs_equal(src->src.ssa, def)) {
return false;
}
nir_def_replace(&phi->def, def);
progress = true;
}
return progress;
if (!def) {
/* In this case, the phi had no non undef sources. So turn it into an undef. */
b->cursor = nir_after_phis(block);
def = nir_undef(b, phi->def.num_components, phi->def.bit_size);
} else if (needs_remat) {
b->cursor = nir_after_block_before_jump(block->imm_dom);
nir_instr *remat = nir_instr_clone(b->shader, def->parent_instr);
nir_builder_instr_insert(b, remat);
def = nir_instr_def(remat);
}
nir_def_replace(&phi->def, def);
return true;
}
bool
nir_opt_remove_phis(nir_shader *shader)
{
nir_foreach_function_impl(impl, shader)
nir_metadata_require(impl, nir_metadata_dominance);
return nir_shader_phi_pass(shader, remove_phis_instr,
nir_metadata_control_flow, NULL);
}
bool
@@ -177,35 +174,3 @@ nir_remove_single_src_phis_block(nir_block *block)
}
return progress;
}
static bool
nir_opt_remove_phis_impl(nir_function_impl *impl)
{
bool progress = false;
nir_builder bld = nir_builder_create(impl);
nir_metadata_require(impl, nir_metadata_dominance);
nir_foreach_block(block, impl) {
progress |= remove_phis_block(block, &bld);
}
if (progress) {
nir_metadata_preserve(impl, nir_metadata_control_flow);
} else {
nir_metadata_preserve(impl, nir_metadata_all);
}
return progress;
}
bool
nir_opt_remove_phis(nir_shader *shader)
{
bool progress = false;
nir_foreach_function_impl(impl, shader)
progress = nir_opt_remove_phis_impl(impl) || progress;
return progress;
}