From a1c688517dee32c57af17d8e11029eb7470f52d4 Mon Sep 17 00:00:00 2001 From: Jason Ekstrand Date: Thu, 13 Dec 2018 12:37:59 -0600 Subject: [PATCH] nir/opt_deref: Properly optimize ptr_as_array derefs MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When handling casts, we can't blindly propagate the parent of a cast into a ptr_as_array deref because doing so might loose the stride information from the cast. Instead, before we can propagate into ptr_as_array derefs, we need to check that the cast is a cast of an array deref and that the stride matches. For other types of derefs, we can continue to propagate casts as normal because they don't need the stride. We also add an optimization which can combine a ptr_as_array deref with it parent if it is also an array deref of some form. Reviewed-by: Alejandro Piñeiro Reviewed-by: Caio Marcelo de Oliveira Filho --- src/compiler/nir/nir_deref.c | 97 +++++++++++++++++++++++++++++++++--- 1 file changed, 91 insertions(+), 6 deletions(-) diff --git a/src/compiler/nir/nir_deref.c b/src/compiler/nir/nir_deref.c index 76bad2dd9db..93f6f90234b 100644 --- a/src/compiler/nir/nir_deref.c +++ b/src/compiler/nir/nir_deref.c @@ -542,26 +542,111 @@ is_trivial_deref_cast(nir_deref_instr *cast) cast->dest.ssa.bit_size == parent->dest.ssa.bit_size; } +static bool +is_trivial_array_deref_cast(nir_deref_instr *cast) +{ + assert(is_trivial_deref_cast(cast)); + + nir_deref_instr *parent = nir_src_as_deref(cast->parent); + + if (parent->deref_type == nir_deref_type_array) { + return cast->cast.ptr_stride == + glsl_get_explicit_stride(nir_deref_instr_parent(parent)->type); + } else if (parent->deref_type == nir_deref_type_ptr_as_array) { + return cast->cast.ptr_stride == + nir_deref_instr_ptr_as_array_stride(parent); + } else { + return false; + } +} + +static bool +is_deref_ptr_as_array(nir_instr *instr) +{ + return instr->type == nir_instr_type_deref && + nir_instr_as_deref(instr)->deref_type == nir_deref_type_ptr_as_array; +} + +static bool +opt_deref_cast(nir_deref_instr *cast) +{ + if (!is_trivial_deref_cast(cast)) + return false; + + bool trivial_array_cast = is_trivial_array_deref_cast(cast); + + assert(cast->dest.is_ssa); + assert(cast->parent.is_ssa); + + bool progress = false; + nir_foreach_use_safe(use_src, &cast->dest.ssa) { + /* If this isn't a trivial array cast, we can't propagate into + * ptr_as_array derefs. + */ + if (is_deref_ptr_as_array(use_src->parent_instr) && + !trivial_array_cast) + continue; + + nir_instr_rewrite_src(use_src->parent_instr, use_src, cast->parent); + progress = true; + } + + /* If uses would be a bit crazy */ + assert(list_empty(&cast->dest.ssa.if_uses)); + + nir_deref_instr_remove_if_unused(cast); + return progress; +} + +static bool +opt_deref_ptr_as_array(nir_builder *b, nir_deref_instr *deref) +{ + assert(deref->deref_type == nir_deref_type_ptr_as_array); + + nir_deref_instr *parent = nir_deref_instr_parent(deref); + if (parent->deref_type != nir_deref_type_array && + parent->deref_type != nir_deref_type_ptr_as_array) + return false; + + assert(parent->parent.is_ssa); + assert(parent->arr.index.is_ssa); + assert(deref->arr.index.is_ssa); + + nir_ssa_def *new_idx = nir_iadd(b, parent->arr.index.ssa, + deref->arr.index.ssa); + + deref->deref_type = parent->deref_type; + nir_instr_rewrite_src(&deref->instr, &deref->parent, parent->parent); + nir_instr_rewrite_src(&deref->instr, &deref->arr.index, + nir_src_for_ssa(new_idx)); + return true; +} + static bool nir_opt_deref_impl(nir_function_impl *impl) { bool progress = false; + nir_builder b; + nir_builder_init(&b, impl); + nir_foreach_block(block, impl) { nir_foreach_instr_safe(instr, block) { if (instr->type != nir_instr_type_deref) continue; + b.cursor = nir_before_instr(instr); + nir_deref_instr *deref = nir_instr_as_deref(instr); switch (deref->deref_type) { + case nir_deref_type_ptr_as_array: + if (opt_deref_ptr_as_array(&b, deref)) + progress = true; + break; + case nir_deref_type_cast: - if (is_trivial_deref_cast(deref)) { - assert(deref->parent.is_ssa); - nir_ssa_def_rewrite_uses(&deref->dest.ssa, - nir_src_for_ssa(deref->parent.ssa)); - nir_instr_remove(&deref->instr); + if (opt_deref_cast(deref)) progress = true; - } break; default: -- 2.30.2