We generate steaming piles of these for the centroid workaround, and this
quickly cleans them up.
total instructions in shared programs: 1591228 -> 1590047 (-0.07%)
instructions in affected programs: 26111 -> 24930 (-4.52%)
GAINED: 0
LOST: 0
(Improved apps are l4d2, csgo, and dolphin)
---
src/mesa/drivers/dri/i965/brw_fs.cpp | 33 +++++++++++++++++++++++++++++++++
src/mesa/drivers/dri/i965/brw_fs.h | 1 +
2 files changed, 34 insertions(+)
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp
b/src/mesa/drivers/dri/i965/brw_fs.cpp
index d35928e..85d36f3 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -3310,6 +3310,37 @@ fs_visitor::calculate_register_pressure()
}
}
+/**
+ * Look for repeated FS_OPCODE_MOV_DISPATCH_TO_FLAGS and drop the later ones.
+ *
+ * The needs_unlit_centroid_workaround ends up producing one of these per
+ * channel of centroid input, so it's good to clean them up.
+ *
+ * An assumption here is that nothing ever modifies the dispatched pixels
+ * value that FS_OPCODE_MOV_DISPATCH_TO_FLAGS reads from, but the hardware
+ * dictates that anyway.
+ */
+void
+fs_visitor::opt_drop_redundant_mov_to_flags()
+{
+ bool flag_mov_found[2] = {false};
+
+ foreach_list_safe(node, &this->instructions) {
+ fs_inst *inst = (fs_inst *)node;
+
+ if (inst->is_control_flow()) {
+ memset(flag_mov_found, 0, sizeof(flag_mov_found));
+ } else if (inst->opcode == FS_OPCODE_MOV_DISPATCH_TO_FLAGS) {
+ if (!flag_mov_found[inst->flag_subreg])
+ flag_mov_found[inst->flag_subreg] = true;
+ else
+ inst->remove();
+ } else if (inst->writes_flag()) {
+ flag_mov_found[inst->flag_subreg] = false;
+ }
+ }
+}
+
bool
fs_visitor::run()
{
@@ -3376,6 +3407,8 @@ fs_visitor::run()
remove_dead_constants();
setup_pull_constants();
+ opt_drop_redundant_mov_to_flags();
+
bool progress;
do {
progress = false;
diff --git a/src/mesa/drivers/dri/i965/brw_fs.h
b/src/mesa/drivers/dri/i965/brw_fs.h
index c6f4ffb..2538983 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.h
+++ b/src/mesa/drivers/dri/i965/brw_fs.h
@@ -352,6 +352,7 @@ public:
bool try_constant_propagate(fs_inst *inst, acp_entry *entry);
bool opt_copy_propagate_local(void *mem_ctx, bblock_t *block,
exec_list *acp);
+ void opt_drop_redundant_mov_to_flags();
bool register_coalesce();
bool compute_to_mrf();
bool dead_code_eliminate();
--
1.9.rc1
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