[Mesa-dev] [PATCH 2/2] nir: allow propagation of if evaluation to all alu instructions

[Timothy Arceri]

With the simplifications to this pass in a3b4cb34589e2f1a68 we
can allow any alu instruction to be processed. For one this can
potentially help with bcsels.

No shader-db change.
---
 src/compiler/nir/nir_opt_if.c | 20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)

diff --git a/src/compiler/nir/nir_opt_if.c b/src/compiler/nir/nir_opt_if.c
index 1fe95e53766..38489676e6b 100644
--- a/src/compiler/nir/nir_opt_if.c
+++ b/src/compiler/nir/nir_opt_if.c
@@ -448,7 +448,7 @@ propagate_condition_eval(nir_builder *b, nir_if *nif, nir_src *use_src,
    if (!evaluate_if_condition(nif, b->cursor, &bool_value))
       return false;
 
-   nir_ssa_def *def[2] = {0};
+   nir_ssa_def *def[4] = {0};
    for (unsigned i = 0; i < nir_op_infos[alu->op].num_inputs; i++) {
       if (alu->src[i].src.ssa == use_src->ssa) {
          def[i] = nir_imm_bool(b, bool_value);
@@ -456,7 +456,7 @@ propagate_condition_eval(nir_builder *b, nir_if *nif, nir_src *use_src,
          def[i] = alu->src[i].src.ssa;
       }
    }
-   nir_ssa_def *nalu = nir_build_alu(b, alu->op, def[0], def[1], NULL, NULL);
+   nir_ssa_def *nalu = nir_build_alu(b, alu->op, def[0], def[1], def[2], def[3]);
 
    /* Rewrite use to use new alu instruction */
    nir_src new_src = nir_src_for_ssa(nalu);
@@ -469,19 +469,6 @@ propagate_condition_eval(nir_builder *b, nir_if *nif, nir_src *use_src,
    return true;
 }
 
-static bool
-can_propagate_through_alu(nir_src *src)
-{
-   if (src->parent_instr->type == nir_instr_type_alu &&
-       (nir_instr_as_alu(src->parent_instr)->op == nir_op_ior ||
-        nir_instr_as_alu(src->parent_instr)->op == nir_op_iand ||
-        nir_instr_as_alu(src->parent_instr)->op == nir_op_inot ||
-        nir_instr_as_alu(src->parent_instr)->op == nir_op_b2i))
-      return true;
-
-   return false;
-}
-
 static bool
 evaluate_condition_use(nir_builder *b, nir_if *nif, nir_src *use_src,
                        bool is_if_condition)
@@ -502,7 +489,8 @@ evaluate_condition_use(nir_builder *b, nir_if *nif, nir_src *use_src,
       progress = true;
    }
 
-   if (!is_if_condition && can_propagate_through_alu(use_src)) {
+   if (!is_if_condition &&
+       use_src->parent_instr->type == nir_instr_type_alu) {
       nir_alu_instr *alu = nir_instr_as_alu(use_src->parent_instr);
 
       nir_foreach_use_safe(alu_use, &alu->dest.dest.ssa) {
-- 
2.17.2