Mesa (master): Revert "nir: propagate known constant values into the if-then branch"

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Module: Mesa
Branch: master
Commit: d8ce915a6156f9669b395c48411ec89997cf2fe8
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d8ce915a6156f9669b395c48411ec89997cf2fe8

Author: Timothy Arceri <tarceri at itsqueeze.com>
Date:   Wed Apr  3 13:24:18 2019 +1100

Revert "nir: propagate known constant values into the if-then branch"

This reverts commit 4218b6422cf1ff70c7f0feeec699a35e88522ed7.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110311

---

 src/compiler/nir/nir_opt_if.c | 60 -------------------------------------------
 1 file changed, 60 deletions(-)

diff --git a/src/compiler/nir/nir_opt_if.c b/src/compiler/nir/nir_opt_if.c
index af63b90f249..4d3183ed151 100644
--- a/src/compiler/nir/nir_opt_if.c
+++ b/src/compiler/nir/nir_opt_if.c
@@ -1326,65 +1326,6 @@ opt_if_merge(nir_if *nif)
    return progress;
 }
 
-/* Perform optimisations based on the values we can derive from the evaluation
- * of if-statement conditions.
- */
-static bool
-opt_for_known_values(nir_builder *b, nir_if *nif)
-{
-   bool progress = false;
-
-   assert(nif->condition.is_ssa);
-   nir_ssa_def *if_cond = nif->condition.ssa;
-
-   if (if_cond->parent_instr->type != nir_instr_type_alu)
-      return false;
-
-   nir_alu_instr *alu = nir_instr_as_alu(if_cond->parent_instr);
-   switch (alu->op) {
-   case nir_op_feq:
-   case nir_op_ieq: {
-      nir_load_const_instr *load_const = NULL;
-      nir_ssa_def *unknown_val = NULL;
-
-      nir_ssa_def *src0 = alu->src[0].src.ssa;
-      nir_ssa_def *src1 = alu->src[1].src.ssa;
-      if (src0->parent_instr->type == nir_instr_type_load_const) {
-         load_const = nir_instr_as_load_const(src0->parent_instr);
-         unknown_val = src1;
-      } else if (src1->parent_instr->type == nir_instr_type_load_const) {
-         load_const = nir_instr_as_load_const(src1->parent_instr);
-         unknown_val = src0;
-      }
-
-      if (!load_const)
-        return false;
-
-      /* TODO: remove this and support swizzles? */
-      if (unknown_val->num_components != 1)
-        return false;
-
-      /* Replace unknown ssa uses with the known constant */
-      nir_foreach_use_safe(use_src, unknown_val) {
-         nir_cursor cursor = nir_before_src(use_src, false);
-         nir_block *use_block = nir_cursor_current_block(cursor);
-         if (nir_block_dominates(nir_if_first_then_block(nif), use_block)) {
-            nir_instr_rewrite_src(use_src->parent_instr, use_src,
-                                  nir_src_for_ssa(&load_const->def));
-            progress = true;
-         }
-      }
-
-      break;
-   }
-
-   default:
-      return false;
-   }
-
-   return progress;
-}
-
 static bool
 opt_if_cf_list(nir_builder *b, struct exec_list *cf_list)
 {
@@ -1439,7 +1380,6 @@ opt_if_safe_cf_list(nir_builder *b, struct exec_list *cf_list)
          progress |= opt_if_safe_cf_list(b, &nif->then_list);
          progress |= opt_if_safe_cf_list(b, &nif->else_list);
          progress |= opt_if_evaluate_condition_use(b, nif);
-         progress |= opt_for_known_values(b, nif);
          break;
       }