Instead of just running a couple of the possible optimisations in one
single iteration, it now runs the whole loop again after lowering the
load payloads. According to shader-db this gives:
total instructions in shared programs: 6493365 -> 6493289 (-0.00%)
instructions in affected programs: 1696 -> 1620 (-4.48%)
total loops in shared programs: 2237 -> 2237 (0.00%)
helped: 20
HURT: 0
Most of the shaders just benefit from running the register coalesce
pass multiple times. However the following two additionally benefit
from an extra pass of opt_saturate_propagation which causes a bunch of
further optimisations:
steam-metro-last-light-1719.shader_test
steam-metro-last-light-836.shader_test
The optimisations that get run after lowering the load payloads are:
04-14-register_coalesce
04-17-compact_virtual_grfs
05-12-opt_saturate_propagation
06-02-opt_algebraic
06-04-opt_copy_propagate
06-07-dead_code_eliminate
06-12-opt_saturate_propagation
06-14-register_coalesce
06-17-compact_virtual_grfs
07-18-opt_combine_constants
In the first shader this drops four instructions.
---
src/mesa/drivers/dri/i965/brw_fs.cpp | 94 +++++++++++++++++++-----------------
src/mesa/drivers/dri/i965/brw_fs.h | 3 ++
2 files changed, 53 insertions(+), 44 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp
b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 01a7c99..8d1db23 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -4754,33 +4754,6 @@ fs_visitor::calculate_register_pressure()
}
}
-void
-fs_visitor::optimize()
-{
- /* Start by validating the shader we currently have. */
- validate();
-
- /* bld is the common builder object pointing at the end of the program we
- * used to translate it into i965 IR. For the optimization and lowering
- * passes coming next, any code added after the end of the program without
- * having explicitly called fs_builder::at() clearly points at a mistake.
- * Ideally optimization passes wouldn't be part of the visitor so they
- * wouldn't have access to bld at all, but they do, so just in case some
- * pass forgets to ask for a location explicitly set it to NULL here to
- * make it trip. The dispatch width is initialized to a bogus value to
- * make sure that optimizations set the execution controls explicitly to
- * match the code they are manipulating instead of relying on the defaults.
- */
- bld = fs_builder(this, 64);
-
- assign_constant_locations();
- demote_pull_constants();
-
- validate();
-
- split_virtual_grfs();
- validate();
-
#define OPT(pass, args...) ({ \
pass_num++; \
bool this_progress = pass(args); \
@@ -4799,20 +4772,10 @@ fs_visitor::optimize()
this_progress; \
})
- if (unlikely(INTEL_DEBUG & DEBUG_OPTIMIZER)) {
- char filename[64];
- snprintf(filename, 64, "%s%d-%s-00-start",
- stage_abbrev, dispatch_width, nir->info.name);
-
- backend_shader::dump_instructions(filename);
- }
-
- bool progress = false;
- int iteration = 0;
- int pass_num = 0;
-
- OPT(lower_simd_width);
- OPT(lower_logical_sends);
+void
+fs_visitor::optimize_loop(int &iteration, int &pass_num)
+{
+ bool progress;
do {
progress = false;
@@ -4839,6 +4802,51 @@ fs_visitor::optimize()
OPT(compact_virtual_grfs);
} while (progress);
+}
+
+void
+fs_visitor::optimize()
+{
+ /* Start by validating the shader we currently have. */
+ validate();
+
+ /* bld is the common builder object pointing at the end of the program we
+ * used to translate it into i965 IR. For the optimization and lowering
+ * passes coming next, any code added after the end of the program without
+ * having explicitly called fs_builder::at() clearly points at a mistake.
+ * Ideally optimization passes wouldn't be part of the visitor so they
+ * wouldn't have access to bld at all, but they do, so just in case some
+ * pass forgets to ask for a location explicitly set it to NULL here to
+ * make it trip. The dispatch width is initialized to a bogus value to
+ * make sure that optimizations set the execution controls explicitly to
+ * match the code they are manipulating instead of relying on the defaults.
+ */
+ bld = fs_builder(this, 64);
+
+ assign_constant_locations();
+ demote_pull_constants();
+
+ validate();
+
+ split_virtual_grfs();
+ validate();
+
+ if (unlikely(INTEL_DEBUG & DEBUG_OPTIMIZER)) {
+ char filename[64];
+ snprintf(filename, 64, "%s%d-%s-00-start",
+ stage_abbrev, dispatch_width, nir->info.name);
+
+ backend_shader::dump_instructions(filename);
+ }
+
+ bool progress = false;
+ int iteration = 0;
+ int pass_num = 0;
+
+ OPT(lower_simd_width);
+ OPT(lower_logical_sends);
+
+ optimize_loop(iteration, pass_num);
pass_num = 0;
@@ -4846,9 +4854,7 @@ fs_visitor::optimize()
if (OPT(lower_load_payload)) {
split_virtual_grfs();
- OPT(register_coalesce);
- OPT(compute_to_mrf);
- OPT(dead_code_eliminate);
+ optimize_loop(iteration, pass_num);
}
OPT(opt_combine_constants);
diff --git a/src/mesa/drivers/dri/i965/brw_fs.h
b/src/mesa/drivers/dri/i965/brw_fs.h
index e8b511f..c12e9e8 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.h
+++ b/src/mesa/drivers/dri/i965/brw_fs.h
@@ -386,6 +386,9 @@ public:
unsigned promoted_constants;
brw::fs_builder bld;
+
+private:
+ void optimize_loop(int &iteration, int &pass_num);
};
/**
--
1.9.3
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