* 12.5 (p356).
*/
-#define ACP_HASH_SIZE 16
+#define ACP_HASH_SIZE 64
#include "util/bitset.h"
+#include "util/u_math.h"
#include "brw_fs.h"
#include "brw_fs_live_variables.h"
#include "brw_cfg.h"
struct acp_entry : public exec_node {
fs_reg dst;
fs_reg src;
+ unsigned global_idx;
uint8_t size_written;
uint8_t size_read;
enum opcode opcode;
foreach_in_list(acp_entry, entry, &out_acp[block->num][i]) {
acp[next_acp] = entry;
+ entry->global_idx = next_acp;
+
/* opt_copy_propagation_local populates out_acp with copies created
* in a block which are still live at the end of the block. This
* is exactly what we want in the COPY set.
fs_copy_prop_dataflow::setup_initial_values()
{
/* Initialize the COPY and KILL sets. */
- foreach_block (block, cfg) {
- foreach_inst_in_block(fs_inst, inst, block) {
- if (inst->dst.file != VGRF)
- continue;
+ {
+ /* Create a temporary table of ACP entries which we'll use for efficient
+ * look-up. Unfortunately, we have to do this in two steps because we
+ * have to match both sources and destinations and an ACP entry can only
+ * be in one list at a time.
+ *
+ * We choose to make the table size between num_acp/2 and num_acp/4 to
+ * try and trade off between the time it takes to initialize the table
+ * via exec_list constructors or make_empty() and the cost of
+ * collisions. In practice, it doesn't appear to matter too much what
+ * size we make the table as long as it's roughly the same order of
+ * magnitude as num_acp. We get most of the benefit of the table
+ * approach even if we use a table of size ACP_HASH_SIZE though a
+ * full-sized table is 1-2% faster in practice.
+ */
+ unsigned acp_table_size = util_next_power_of_two(num_acp) / 4;
+ acp_table_size = MAX2(acp_table_size, ACP_HASH_SIZE);
+ exec_list *acp_table = new exec_list[acp_table_size];
- /* Mark ACP entries which are killed by this instruction. */
- for (int i = 0; i < num_acp; i++) {
- if (regions_overlap(inst->dst, inst->size_written,
- acp[i]->dst, acp[i]->size_written) ||
- regions_overlap(inst->dst, inst->size_written,
- acp[i]->src, acp[i]->size_read)) {
- BITSET_SET(bd[block->num].kill, i);
+ /* First, get all the KILLs for instructions which overwrite ACP
+ * destinations.
+ */
+ for (int i = 0; i < num_acp; i++) {
+ unsigned idx = acp[i]->dst.nr & (acp_table_size - 1);
+ acp_table[idx].push_tail(acp[i]);
+ }
+
+ foreach_block (block, cfg) {
+ foreach_inst_in_block(fs_inst, inst, block) {
+ if (inst->dst.file != VGRF)
+ continue;
+
+ unsigned idx = inst->dst.nr & (acp_table_size - 1);
+ foreach_in_list(acp_entry, entry, &acp_table[idx]) {
+ if (regions_overlap(inst->dst, inst->size_written,
+ entry->dst, entry->size_written))
+ BITSET_SET(bd[block->num].kill, entry->global_idx);
}
}
}
+
+ /* Clear the table for the second pass */
+ for (unsigned i = 0; i < acp_table_size; i++)
+ acp_table[i].make_empty();
+
+ /* Next, get all the KILLs for instructions which overwrite ACP
+ * sources.
+ */
+ for (int i = 0; i < num_acp; i++) {
+ unsigned idx = acp[i]->src.nr & (acp_table_size - 1);
+ acp_table[idx].push_tail(acp[i]);
+ }
+
+ foreach_block (block, cfg) {
+ foreach_inst_in_block(fs_inst, inst, block) {
+ if (inst->dst.file != VGRF)
+ continue;
+
+ unsigned idx = inst->dst.nr & (acp_table_size - 1);
+ foreach_in_list(acp_entry, entry, &acp_table[idx]) {
+ if (regions_overlap(inst->dst, inst->size_written,
+ entry->src, entry->size_read))
+ BITSET_SET(bd[block->num].kill, entry->global_idx);
+ }
+ }
+ }
+
+ delete [] acp_table;
}
/* Populate the initial values for the livein and liveout sets. For the
/* Compute the first component of the copy that the instruction is
* reading, and the base byte offset within that component.
*/
- assert(entry->dst.stride == 1);
+ assert(entry->dst.offset % REG_SIZE == 0 && entry->dst.stride == 1);
const unsigned component = rel_offset / type_sz(entry->dst.type);
const unsigned suboffset = rel_offset % type_sz(entry->dst.type);
}
static bool
-can_propagate_from(fs_inst *inst, unsigned dispatch_width)
+can_propagate_from(fs_inst *inst)
{
return (inst->opcode == BRW_OPCODE_MOV &&
inst->dst.file == VGRF &&
inst->src[0].file == UNIFORM ||
inst->src[0].file == IMM) &&
inst->src[0].type == inst->dst.type &&
- !inst->is_partial_var_write(dispatch_width));
+ !inst->is_partial_write());
}
/* Walks a basic block and does copy propagation on it using the acp
/* If this instruction's source could potentially be folded into the
* operand of another instruction, add it to the ACP.
*/
- if (can_propagate_from(inst, dispatch_width)) {
+ if (can_propagate_from(inst)) {
acp_entry *entry = ralloc(copy_prop_ctx, acp_entry);
entry->dst = inst->dst;
entry->src = inst->src[0];
foreach_block (block, cfg) {
progress = opt_copy_propagation_local(copy_prop_ctx, block,
out_acp[block->num]) || progress;
+
+ /* If the destination of an ACP entry exists only within this block,
+ * then there's no need to keep it for dataflow analysis. We can delete
+ * it from the out_acp table and avoid growing the bitsets any bigger
+ * than we absolutely have to.
+ *
+ * Because nothing in opt_copy_propagation_local touches the block
+ * start/end IPs and opt_copy_propagation_local is incapable of
+ * extending the live range of an ACP destination beyond the block,
+ * it's safe to use the liveness information in this way.
+ */
+ for (unsigned a = 0; a < ACP_HASH_SIZE; a++) {
+ foreach_in_list_safe(acp_entry, entry, &out_acp[block->num][a]) {
+ assert(entry->dst.file == VGRF);
+ if (block->start_ip <= virtual_grf_start[entry->dst.nr] &&
+ virtual_grf_end[entry->dst.nr] <= block->end_ip)
+ entry->remove();
+ }
+ }
}
/* Do dataflow analysis for those available copies. */
projects / mesa.git / blobdiff