From 88d7e1b1bed2940062e5ac5807e93159c33944e2 Mon Sep 17 00:00:00 2001 From: Iago Toral Quiroga Date: Mon, 28 Apr 2014 11:20:31 +0200 Subject: [PATCH] i965: Relax accumulator dependency scheduling on Gen < 6 Many instructions implicitly update the accumulator on Gen < 6. The instruction scheduling code just calls add_barrier_deps() for each accumulator access on these platforms, but a large class of operations don't actually update the accumulator -- mostly move and logical instructions. Teaching the scheduling code about this would allow more flexibility to schedule instructions. --- .../drivers/dri/i965/brw_schedule_instructions.cpp | 82 ++++++---------------- src/mesa/drivers/dri/i965/brw_shader.cpp | 7 ++ src/mesa/drivers/dri/i965/brw_shader.h | 1 + 3 files changed, 31 insertions(+), 59 deletions(-) diff --git a/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp b/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp index 8cc6908..96715d0 100644 --- a/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp +++ b/src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp @@ -742,8 +742,6 @@ fs_instruction_scheduler::is_compressed(fs_inst *inst) void fs_instruction_scheduler::calculate_deps() { - const bool gen6plus = v->brw->gen >= 6; - /* Pre-register-allocation, this tracks the last write per VGRF (so * different reg_offsets within it can interfere when they shouldn't). * After register allocation, reg_offsets are gone and we track individual @@ -803,7 +801,7 @@ fs_instruction_scheduler::calculate_deps() } else { add_dep(last_fixed_grf_write, n); } - } else if (inst->src[i].is_accumulator() && gen6plus) { + } else if (inst->src[i].is_accumulator()) { add_dep(last_accumulator_write, n); } else if (inst->src[i].file != BAD_FILE && inst->src[i].file != IMM && @@ -828,11 +826,7 @@ fs_instruction_scheduler::calculate_deps() } if (inst->reads_accumulator_implicitly()) { - if (gen6plus) { - add_dep(last_accumulator_write, n); - } else { - add_barrier_deps(n); - } + add_dep(last_accumulator_write, n); } /* write-after-write deps. */ @@ -867,7 +861,7 @@ fs_instruction_scheduler::calculate_deps() } else { last_fixed_grf_write = n; } - } else if (inst->dst.is_accumulator() && gen6plus) { + } else if (inst->dst.is_accumulator()) { add_dep(last_accumulator_write, n); last_accumulator_write = n; } else if (inst->dst.file != BAD_FILE && @@ -887,13 +881,9 @@ fs_instruction_scheduler::calculate_deps() last_conditional_mod[inst->flag_subreg] = n; } - if (inst->writes_accumulator) { - if (gen6plus) { - add_dep(last_accumulator_write, n); - last_accumulator_write = n; - } else { - add_barrier_deps(n); - } + if (inst->writes_accumulator_implicitly(v->brw->gen)) { + add_dep(last_accumulator_write, n); + last_accumulator_write = n; } } @@ -933,7 +923,7 @@ fs_instruction_scheduler::calculate_deps() } else { add_dep(n, last_fixed_grf_write); } - } else if (inst->src[i].is_accumulator() && gen6plus) { + } else if (inst->src[i].is_accumulator()) { add_dep(n, last_accumulator_write); } else if (inst->src[i].file != BAD_FILE && inst->src[i].file != IMM && @@ -958,11 +948,7 @@ fs_instruction_scheduler::calculate_deps() } if (inst->reads_accumulator_implicitly()) { - if (gen6plus) { - add_dep(n, last_accumulator_write); - } else { - add_barrier_deps(n); - } + add_dep(n, last_accumulator_write); } /* Update the things this instruction wrote, so earlier reads @@ -996,7 +982,7 @@ fs_instruction_scheduler::calculate_deps() } else { last_fixed_grf_write = n; } - } else if (inst->dst.is_accumulator() && gen6plus) { + } else if (inst->dst.is_accumulator()) { last_accumulator_write = n; } else if (inst->dst.file != BAD_FILE && !inst->dst.is_null()) { @@ -1013,12 +999,8 @@ fs_instruction_scheduler::calculate_deps() last_conditional_mod[inst->flag_subreg] = n; } - if (inst->writes_accumulator) { - if (gen6plus) { - last_accumulator_write = n; - } else { - add_barrier_deps(n); - } + if (inst->writes_accumulator_implicitly(v->brw->gen)) { + last_accumulator_write = n; } } } @@ -1026,8 +1008,6 @@ fs_instruction_scheduler::calculate_deps() void vec4_instruction_scheduler::calculate_deps() { - const bool gen6plus = v->brw->gen >= 6; - schedule_node *last_grf_write[grf_count]; schedule_node *last_mrf_write[BRW_MAX_MRF]; schedule_node *last_conditional_mod = NULL; @@ -1067,7 +1047,7 @@ vec4_instruction_scheduler::calculate_deps() (inst->src[i].fixed_hw_reg.file == BRW_GENERAL_REGISTER_FILE)) { add_dep(last_fixed_grf_write, n); - } else if (inst->src[i].is_accumulator() && gen6plus) { + } else if (inst->src[i].is_accumulator()) { assert(last_accumulator_write); add_dep(last_accumulator_write, n); } else if (inst->src[i].file != BAD_FILE && @@ -1094,12 +1074,8 @@ vec4_instruction_scheduler::calculate_deps() } if (inst->reads_accumulator_implicitly()) { - if (gen6plus) { - assert(last_accumulator_write); - add_dep(last_accumulator_write, n); - } else { - add_barrier_deps(n); - } + assert(last_accumulator_write); + add_dep(last_accumulator_write, n); } /* write-after-write deps. */ @@ -1112,7 +1088,7 @@ vec4_instruction_scheduler::calculate_deps() } else if (inst->dst.file == HW_REG && inst->dst.fixed_hw_reg.file == BRW_GENERAL_REGISTER_FILE) { last_fixed_grf_write = n; - } else if (inst->dst.is_accumulator() && gen6plus) { + } else if (inst->dst.is_accumulator()) { add_dep(last_accumulator_write, n); last_accumulator_write = n; } else if (inst->dst.file != BAD_FILE && @@ -1132,13 +1108,9 @@ vec4_instruction_scheduler::calculate_deps() last_conditional_mod = n; } - if (inst->writes_accumulator) { - if (gen6plus) { - add_dep(last_accumulator_write, n); - last_accumulator_write = n; - } else { - add_barrier_deps(n); - } + if (inst->writes_accumulator_implicitly(v->brw->gen)) { + add_dep(last_accumulator_write, n); + last_accumulator_write = n; } } @@ -1165,7 +1137,7 @@ vec4_instruction_scheduler::calculate_deps() (inst->src[i].fixed_hw_reg.file == BRW_GENERAL_REGISTER_FILE)) { add_dep(n, last_fixed_grf_write); - } else if (inst->src[i].is_accumulator() && gen6plus) { + } else if (inst->src[i].is_accumulator()) { add_dep(n, last_accumulator_write); } else if (inst->src[i].file != BAD_FILE && inst->src[i].file != IMM && @@ -1189,11 +1161,7 @@ vec4_instruction_scheduler::calculate_deps() } if (inst->reads_accumulator_implicitly()) { - if (gen6plus) { - add_dep(n, last_accumulator_write); - } else { - add_barrier_deps(n); - } + add_dep(n, last_accumulator_write); } /* Update the things this instruction wrote, so earlier reads @@ -1206,7 +1174,7 @@ vec4_instruction_scheduler::calculate_deps() } else if (inst->dst.file == HW_REG && inst->dst.fixed_hw_reg.file == BRW_GENERAL_REGISTER_FILE) { last_fixed_grf_write = n; - } else if (inst->dst.is_accumulator() && gen6plus) { + } else if (inst->dst.is_accumulator()) { last_accumulator_write = n; } else if (inst->dst.file != BAD_FILE && !inst->dst.is_null()) { @@ -1223,12 +1191,8 @@ vec4_instruction_scheduler::calculate_deps() last_conditional_mod = n; } - if (inst->writes_accumulator) { - if (gen6plus) { - last_accumulator_write = n; - } else { - add_barrier_deps(n); - } + if (inst->writes_accumulator_implicitly(v->brw->gen)) { + last_accumulator_write = n; } } } diff --git a/src/mesa/drivers/dri/i965/brw_shader.cpp b/src/mesa/drivers/dri/i965/brw_shader.cpp index 6e74803..ee3b9ea 100644 --- a/src/mesa/drivers/dri/i965/brw_shader.cpp +++ b/src/mesa/drivers/dri/i965/brw_shader.cpp @@ -676,6 +676,13 @@ backend_instruction::reads_accumulator_implicitly() const } bool +backend_instruction::writes_accumulator_implicitly(int gen) const +{ + return writes_accumulator || + (gen <=5 && opcode >= BRW_OPCODE_ADD && opcode != BRW_OPCODE_NOP); +} + +bool backend_instruction::has_side_effects() const { switch (opcode) { diff --git a/src/mesa/drivers/dri/i965/brw_shader.h b/src/mesa/drivers/dri/i965/brw_shader.h index e730ed0..5ae4092 100644 --- a/src/mesa/drivers/dri/i965/brw_shader.h +++ b/src/mesa/drivers/dri/i965/brw_shader.h @@ -48,6 +48,7 @@ public: bool can_do_source_mods() const; bool can_do_saturate() const; bool reads_accumulator_implicitly() const; + bool writes_accumulator_implicitly(int gen) const; /** * True if the instruction has side effects other than writing to -- 1.8.3.2