[Mesa-dev] [PATCH 09/10] nir: evaluate loop terminator ior use

[Timothy Arceri]

Here we replace one side of the ior with NIR_TRUE if the src is a
loop terminators condition that we know can only be true.

No shader-db change.
---
 src/compiler/nir/nir_opt_if.c | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/compiler/nir/nir_opt_if.c b/src/compiler/nir/nir_opt_if.c
index 83f2141dff6..7b8085452ce 100644
--- a/src/compiler/nir/nir_opt_if.c
+++ b/src/compiler/nir/nir_opt_if.c
@@ -505,9 +505,31 @@ opt_if_evaluate_condition_use_loop_terminator(nir_if *nif, nir_loop *loop,
    /* Evaluate any uses of the loop terminator condition */
    assert(nif->condition.is_ssa);
    nir_foreach_use_safe(use_src, nif->condition.ssa) {
-      progress =
-         evaluate_term_condition_use(prev_block->index, after_loop->index,
-                                     nir_boolean, use_src, mem_ctx, false);
+      nir_instr *parent_instr = use_src->parent_instr;
+      if (nir_boolean == NIR_TRUE &&
+          parent_instr->type == nir_instr_type_alu &&
+          nir_instr_as_alu(parent_instr)->op == nir_op_ior) {
+
+         nir_alu_instr *alu = nir_instr_as_alu(parent_instr);
+
+         nir_foreach_use_safe(or_use, &alu->dest.dest.ssa) {
+            progress =
+               evaluate_term_condition_use(prev_block->index,
+                                           after_loop->index, NIR_TRUE,
+                                           or_use, mem_ctx, false);
+         }
+
+         nir_foreach_if_use_safe(or_use, &alu->dest.dest.ssa) {
+            progress =
+               evaluate_term_condition_use(prev_block->index,
+                                           after_loop->index, NIR_TRUE,
+                                           or_use, mem_ctx, true);
+         }
+      } else {
+         progress =
+            evaluate_term_condition_use(prev_block->index, after_loop->index,
+                                        nir_boolean, use_src, mem_ctx, false);
+      }
    }
 
    nir_foreach_if_use_safe(use_src, nif->condition.ssa) {
-- 
2.17.1