From: Ian Romanick <ian.d.roman...@intel.com>
Invert the condition and just emit the non-empty else-branch.
total instructions in shared programs: 8448571 -> 8448373 (-0.00%)
instructions in affected programs: 20880 -> 20682 (-0.95%)
helped: 114
HURT: 0
Jason suggested that there were several places that tried to determine
that a flow control path had no instructions and the code should be
refactored. Using 'grep -r is_empty' in src/mesa/drivers/dri/i965 and
src/compiler/nir, I could not find any such locations. As a result, I
just open coded the check. Did I just miss the other occurrences?
Signed-off-by: Ian Romanick <ian.d.roman...@intel.com>
---
src/mesa/drivers/dri/i965/brw_fs_nir.cpp | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
index db20c71..06e8aff 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
@@ -417,13 +417,21 @@ fs_visitor::nir_emit_if(nir_if *if_stmt)
BRW_REGISTER_TYPE_D));
inst->conditional_mod = BRW_CONDITIONAL_NZ;
- bld.IF(BRW_PREDICATE_NORMAL);
+ fs_inst *if_inst = bld.IF(BRW_PREDICATE_NORMAL);
- nir_emit_cf_list(&if_stmt->then_list);
+ const nir_cf_node *const cf = nir_if_first_then_node(if_stmt);
+ const nir_block *const block = nir_cf_node_as_block(cf);
- /* note: if the else is empty, dead CF elimination will remove it */
- bld.emit(BRW_OPCODE_ELSE);
+ /* If the then-list has no instructions, don't emit it. */
+ if (nir_cf_node_is_last(cf) && block->instr_list.is_empty()) {
+ if_inst->predicate_inverse = true;
+ } else {
+ nir_emit_cf_list(&if_stmt->then_list);
+ bld.emit(BRW_OPCODE_ELSE);
+ }
+
+ /* note: if the else is empty, dead CF elimination will remove it */
nir_emit_cf_list(&if_stmt->else_list);
bld.emit(BRW_OPCODE_ENDIF);
--
2.5.0
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/mesa-dev
