Mesa (master): vc4: Add separate write-after-read dependency tracking for pairing.
Eric Anholt
anholt at kemper.freedesktop.org
Fri Dec 5 19:19:20 UTC 2014
Module: Mesa
Branch: master
Commit: 6f32deb538b1b62ff6d5d1212105bbe8d6adce72
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=6f32deb538b1b62ff6d5d1212105bbe8d6adce72
Author: Eric Anholt <eric at anholt.net>
Date: Tue Dec 2 15:42:58 2014 -0800
vc4: Add separate write-after-read dependency tracking for pairing.
If an operation is the last one to read a register, the instruction
containing it can also include the op that has the next write to that
register.
total instructions in shared programs: 57486 -> 56995 (-0.85%)
instructions in affected programs: 43004 -> 42513 (-1.14%)
---
src/gallium/drivers/vc4/vc4_qpu_schedule.c | 78 +++++++++++++++++++++-------
1 file changed, 58 insertions(+), 20 deletions(-)
diff --git a/src/gallium/drivers/vc4/vc4_qpu_schedule.c b/src/gallium/drivers/vc4/vc4_qpu_schedule.c
index 2b0a632..6bba66a 100644
--- a/src/gallium/drivers/vc4/vc4_qpu_schedule.c
+++ b/src/gallium/drivers/vc4/vc4_qpu_schedule.c
@@ -40,16 +40,23 @@
static bool debug;
+struct schedule_node_child;
+
struct schedule_node {
struct simple_node link;
struct queued_qpu_inst *inst;
- struct schedule_node **children;
+ struct schedule_node_child *children;
uint32_t child_count;
uint32_t child_array_size;
uint32_t parent_count;
uint32_t delay;
};
+struct schedule_node_child {
+ struct schedule_node *node;
+ bool write_after_read;
+};
+
/* When walking the instructions in reverse, we need to swap before/after in
* add_dep().
*/
@@ -71,8 +78,11 @@ struct schedule_state {
static void
add_dep(struct schedule_state *state,
struct schedule_node *before,
- struct schedule_node *after)
+ struct schedule_node *after,
+ bool write)
{
+ bool write_after_read = !write && state->dir == R;
+
if (!before || !after)
return;
@@ -85,28 +95,40 @@ add_dep(struct schedule_state *state,
}
for (int i = 0; i < before->child_count; i++) {
- if (before->children[i] == after)
+ if (before->children[i].node == after &&
+ (before->children[i].write_after_read == write_after_read)) {
return;
+ }
}
if (before->child_array_size <= before->child_count) {
before->child_array_size = MAX2(before->child_array_size * 2, 16);
before->children = reralloc(before, before->children,
- struct schedule_node *,
+ struct schedule_node_child,
before->child_array_size);
}
- before->children[before->child_count] = after;
+ before->children[before->child_count].node = after;
+ before->children[before->child_count].write_after_read =
+ write_after_read;
before->child_count++;
after->parent_count++;
}
static void
+add_read_dep(struct schedule_state *state,
+ struct schedule_node *before,
+ struct schedule_node *after)
+{
+ add_dep(state, before, after, false);
+}
+
+static void
add_write_dep(struct schedule_state *state,
struct schedule_node **before,
struct schedule_node *after)
{
- add_dep(state, *before, after);
+ add_dep(state, *before, after, true);
*before = after;
}
@@ -152,9 +174,9 @@ process_raddr_deps(struct schedule_state *state, struct schedule_node *n,
default:
if (raddr < 32) {
if (is_a)
- add_dep(state, state->last_ra[raddr], n);
+ add_read_dep(state, state->last_ra[raddr], n);
else
- add_dep(state, state->last_rb[raddr], n);
+ add_read_dep(state, state->last_rb[raddr], n);
} else {
fprintf(stderr, "unknown raddr %d\n", raddr);
abort();
@@ -186,7 +208,7 @@ process_mux_deps(struct schedule_state *state, struct schedule_node *n,
uint32_t mux)
{
if (mux != QPU_MUX_A && mux != QPU_MUX_B)
- add_dep(state, state->last_r[mux], n);
+ add_read_dep(state, state->last_r[mux], n);
}
@@ -278,7 +300,7 @@ process_cond_deps(struct schedule_state *state, struct schedule_node *n,
case QPU_COND_ALWAYS:
break;
default:
- add_dep(state, state->last_sf, n);
+ add_read_dep(state, state->last_sf, n);
break;
}
}
@@ -339,7 +361,7 @@ calculate_deps(struct schedule_state *state, struct schedule_node *n)
break;
case QPU_SIG_COLOR_LOAD:
- add_dep(state, state->last_tlb, n);
+ add_read_dep(state, state->last_tlb, n);
break;
case QPU_SIG_PROG_END:
@@ -557,10 +579,15 @@ dump_state(struct simple_node *schedule_list)
fprintf(stderr, "\n");
for (int i = 0; i < n->child_count; i++) {
- struct schedule_node *child = n->children[i];
+ struct schedule_node *child = n->children[i].node;
+ if (!child)
+ continue;
+
fprintf(stderr, " - ");
vc4_qpu_disasm(&child->inst->inst, 1);
- fprintf(stderr, " (%d parents)\n", child->parent_count);
+ fprintf(stderr, " (%d parents, %c)\n",
+ child->parent_count,
+ n->children[i].write_after_read ? 'w' : 'r');
}
}
}
@@ -573,27 +600,37 @@ compute_delay(struct schedule_node *n)
n->delay = 1;
} else {
for (int i = 0; i < n->child_count; i++) {
- if (!n->children[i]->delay)
- compute_delay(n->children[i]);
- n->delay = MAX2(n->delay, n->children[i]->delay + 1);
+ if (!n->children[i].node->delay)
+ compute_delay(n->children[i].node);
+ n->delay = MAX2(n->delay,
+ n->children[i].node->delay + 1);
}
}
}
static void
mark_instruction_scheduled(struct simple_node *schedule_list,
- struct schedule_node *node)
+ struct schedule_node *node,
+ bool war_only)
{
if (!node)
return;
for (int i = node->child_count - 1; i >= 0; i--) {
struct schedule_node *child =
- node->children[i];
+ node->children[i].node;
+
+ if (!child)
+ continue;
+
+ if (war_only && !node->children[i].write_after_read)
+ continue;
child->parent_count--;
if (child->parent_count == 0)
insert_at_head(schedule_list, &child->link);
+
+ node->children[i].node = NULL;
}
}
@@ -647,6 +684,7 @@ schedule_instructions(struct vc4_compile *c, struct simple_node *schedule_list)
*/
if (chosen) {
remove_from_list(&chosen->link);
+ mark_instruction_scheduled(schedule_list, chosen, true);
merge = choose_instruction_to_schedule(&scoreboard,
schedule_list,
@@ -680,8 +718,8 @@ schedule_instructions(struct vc4_compile *c, struct simple_node *schedule_list)
* be scheduled. Update the children's unblocked time for this
* DAG edge as we do so.
*/
- mark_instruction_scheduled(schedule_list, chosen);
- mark_instruction_scheduled(schedule_list, merge);
+ mark_instruction_scheduled(schedule_list, chosen, false);
+ mark_instruction_scheduled(schedule_list, merge, false);
scoreboard.tick++;
}
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