[Mesa-dev] [PATCH 2/6] i965/sched: write-after-read dependencies are free

[Connor Abbott]

Although write-after-write dependencies have the same latency as
read-after-write dependencies due to how the register scoreboard works,
write-after-read dependencies aren't checked by the EU at all, so
they're purely a constraint on how the scheduler can order the
instructions.

Signed-off-by: Connor Abbott <cwabbott0 at gmail.com>
---
 src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp | 8 ++++----
 1 file changed, 4 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 76d58e2..1652261 100644
--- a/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp
+++ b/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp
@@ -927,10 +927,10 @@ fs_instruction_scheduler::calculate_deps()
          if (inst->src[i].file == GRF) {
             if (post_reg_alloc) {
                for (int r = 0; r < inst->regs_read(i); r++)
-                  add_dep(n, last_grf_write[inst->src[i].reg + r]);
+                  add_dep(n, last_grf_write[inst->src[i].reg + r], 0);
             } else {
                for (int r = 0; r < inst->regs_read(i); r++) {
-                  add_dep(n, last_grf_write[inst->src[i].reg * 16 + inst->src[i].reg_offset + r]);
+                  add_dep(n, last_grf_write[inst->src[i].reg * 16 + inst->src[i].reg_offset + r], 0);
                }
             }
          } else if (inst->src[i].file == HW_REG &&
@@ -941,9 +941,9 @@ fs_instruction_scheduler::calculate_deps()
                if (inst->src[i].fixed_hw_reg.vstride == BRW_VERTICAL_STRIDE_0)
                   size = 1;
                for (int r = 0; r < size; r++)
-                  add_dep(n, last_grf_write[inst->src[i].fixed_hw_reg.nr + r]);
+                  add_dep(n, last_grf_write[inst->src[i].fixed_hw_reg.nr + r], 0);
             } else {
-               add_dep(n, last_fixed_grf_write);
+               add_dep(n, last_fixed_grf_write, 0);
             }
          } else if (inst->src[i].is_accumulator()) {
             add_dep(n, last_accumulator_write);
-- 
2.1.0