Mesa (master): i965: Don' t make instructions with a null dest a barrier to scheduling.

[Matt Turner]

Module: Mesa
Branch: master
Commit: 42a26cb5e441a01d5288b299980f23affaad53fe
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=42a26cb5e441a01d5288b299980f23affaad53fe

Author: Matt Turner <mattst88 at gmail.com>
Date:   Wed Apr  9 13:38:14 2014 -0700

i965: Don't make instructions with a null dest a barrier to scheduling.

Now that we properly track accumulator dependencies, the scheduler is
able to schedule instructions between the mach and mov in the common
the integer multiplication pattern:

   mul  acc0, x, y
   mach null, x, y
   mov  dest, acc0

Since a null destination implies no dependency on the destination, we
can also safely schedule instructions (that don't write the accumulator)
between the mul and mach.

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

---

 src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp b/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp
index 5e4f2fe..8cc6908 100644
--- a/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp
+++ b/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp
@@ -870,7 +870,8 @@ fs_instruction_scheduler::calculate_deps()
       } else if (inst->dst.is_accumulator() && gen6plus) {
          add_dep(last_accumulator_write, n);
          last_accumulator_write = n;
-      } else if (inst->dst.file != BAD_FILE) {
+      } else if (inst->dst.file != BAD_FILE &&
+                 !inst->dst.is_null()) {
 	 add_barrier_deps(n);
       }
 
@@ -997,7 +998,8 @@ fs_instruction_scheduler::calculate_deps()
          }
       } else if (inst->dst.is_accumulator() && gen6plus) {
          last_accumulator_write = n;
-      } else if (inst->dst.file != BAD_FILE) {
+      } else if (inst->dst.file != BAD_FILE &&
+                 !inst->dst.is_null()) {
 	 add_barrier_deps(n);
       }
 
@@ -1113,7 +1115,8 @@ vec4_instruction_scheduler::calculate_deps()
       } else if (inst->dst.is_accumulator() && gen6plus) {
          add_dep(last_accumulator_write, n);
          last_accumulator_write = n;
-      } else if (inst->dst.file != BAD_FILE) {
+      } else if (inst->dst.file != BAD_FILE &&
+                 !inst->dst.is_null()) {
          add_barrier_deps(n);
       }
 
@@ -1205,7 +1208,8 @@ vec4_instruction_scheduler::calculate_deps()
          last_fixed_grf_write = n;
       } else if (inst->dst.is_accumulator() && gen6plus) {
          last_accumulator_write = n;
-      } else if (inst->dst.file != BAD_FILE) {
+      } else if (inst->dst.file != BAD_FILE &&
+                 !inst->dst.is_null()) {
          add_barrier_deps(n);
       }