* IN THE SOFTWARE.
*/
+/** @file brw_fs_copy_propagation.cpp
+ *
+ * Support for global copy propagation in two passes: A local pass that does
+ * intra-block copy (and constant) propagation, and a global pass that uses
+ * dataflow analysis on the copies available at the end of each block to re-do
+ * local copy propagation with more copies available.
+ *
+ * See Muchnik's Advanced Compiler Design and Implementation, section
+ * 12.5 (p356).
+ */
+
+#define ACP_HASH_SIZE 16
+
#include "brw_fs.h"
#include "brw_cfg.h"
fs_reg dst;
fs_reg src;
};
+
+struct block_data {
+ /**
+ * Which entries in the fs_copy_prop_dataflow acp table are live at the
+ * start of this block. This is the useful output of the analysis, since
+ * it lets us plug those into the local copy propagation on the second
+ * pass.
+ */
+ bool *livein;
+
+ /**
+ * Which entries in the fs_copy_prop_dataflow acp table are live at the end
+ * of this block. This is done in initial setup from the per-block acps
+ * returned by the first local copy prop pass.
+ */
+ bool *liveout;
+
+ /**
+ * Which entries in the fs_copy_prop_dataflow acp table are killed over the
+ * course of this block.
+ */
+ bool *kill;
+};
+
+class fs_copy_prop_dataflow
+{
+public:
+ fs_copy_prop_dataflow(void *mem_ctx, cfg_t *cfg,
+ exec_list out_acp[][ACP_HASH_SIZE]);
+
+ void setup_kills();
+ void run();
+
+ void *mem_ctx;
+ cfg_t *cfg;
+
+ acp_entry **acp;
+ int num_acp;
+
+ struct block_data *bd;
+};
+} /* anonymous namespace */
+
+fs_copy_prop_dataflow::fs_copy_prop_dataflow(void *mem_ctx, cfg_t *cfg,
+ exec_list out_acp[][ACP_HASH_SIZE])
+ : mem_ctx(mem_ctx), cfg(cfg)
+{
+ bd = rzalloc_array(mem_ctx, struct block_data, cfg->num_blocks);
+
+ num_acp = 0;
+ for (int b = 0; b < cfg->num_blocks; b++) {
+ for (int i = 0; i < ACP_HASH_SIZE; i++) {
+ foreach_list(entry_node, &out_acp[b][i]) {
+ num_acp++;
+ }
+ }
+ }
+
+ acp = rzalloc_array(mem_ctx, struct acp_entry *, num_acp);
+
+ int next_acp = 0;
+ for (int b = 0; b < cfg->num_blocks; b++) {
+ bd[b].livein = rzalloc_array(bd, bool, num_acp);
+ bd[b].liveout = rzalloc_array(bd, bool, num_acp);
+ bd[b].kill = rzalloc_array(bd, bool, num_acp);
+
+ for (int i = 0; i < ACP_HASH_SIZE; i++) {
+ foreach_list(entry_node, &out_acp[b][i]) {
+ acp_entry *entry = (acp_entry *)entry_node;
+
+ acp[next_acp] = entry;
+ bd[b].liveout[next_acp] = true;
+ next_acp++;
+ }
+ }
+ }
+
+ assert(next_acp == num_acp);
+
+ setup_kills();
+ run();
+}
+
+/**
+ * Walk the set of instructions in the block, marking which entries in the acp
+ * are killed by the block.
+ */
+void
+fs_copy_prop_dataflow::setup_kills()
+{
+ for (int b = 0; b < cfg->num_blocks; b++) {
+ bblock_t *block = cfg->blocks[b];
+
+ for (fs_inst *inst = (fs_inst *)block->start;
+ inst != block->end->next;
+ inst = (fs_inst *)inst->next) {
+ if (inst->dst.file != GRF)
+ continue;
+
+ for (int i = 0; i < num_acp; i++) {
+ if (inst->overwrites_reg(acp[i]->dst) ||
+ inst->overwrites_reg(acp[i]->src)) {
+ bd[b].kill[i] = true;
+ }
+ }
+ }
+ }
+}
+
+/**
+ * Walk the set of instructions in the block, marking which entries in the acp
+ * are killed by the block.
+ */
+void
+fs_copy_prop_dataflow::run()
+{
+ bool cont = true;
+
+ while (cont) {
+ cont = false;
+
+ for (int b = 0; b < cfg->num_blocks; b++) {
+ for (int i = 0; i < num_acp; i++) {
+ if (!bd[b].liveout[i]) {
+ /* Update liveout */
+ if (bd[b].livein[i] && !bd[b].kill[i]) {
+ bd[b].liveout[i] = true;
+ cont = true;
+ }
+ }
+
+ if (!bd[b].livein[i]) {
+ /* Update livein: if it's live at the end of all parents, it's
+ * live at our start.
+ */
+ bool add = true;
+ foreach_list(block_node, &cfg->blocks[b]->parents) {
+ bblock_link *link = (bblock_link *)block_node;
+ bblock_t *block = link->block;
+ if (!bd[block->block_num].liveout[i]) {
+ add = false;
+ break;
+ }
+ }
+ if (add) {
+ bd[b].livein[i] = true;
+ cont = true;
+ }
+ }
+ }
+ }
+ }
}
bool
return progress;
}
-
-/** @file brw_fs_copy_propagation.cpp
- *
- * Support for local copy propagation by walking the list of instructions
- * and maintaining the ACP table of available copies for propagation.
- *
- * See Muchnik's Advanced Compiler Design and Implementation, section
- * 12.5 (p356).
- */
-
/* Walks a basic block and does copy propagation on it using the acp
* list.
*/
bool
-fs_visitor::opt_copy_propagate_local(void *mem_ctx, bblock_t *block)
+fs_visitor::opt_copy_propagate_local(void *mem_ctx, bblock_t *block,
+ exec_list *acp)
{
bool progress = false;
- int acp_count = 16;
- exec_list acp[acp_count];
for (fs_inst *inst = (fs_inst *)block->start;
inst != block->end->next;
if (inst->src[i].file != GRF)
continue;
- foreach_list(entry_node, &acp[inst->src[i].reg % acp_count]) {
+ foreach_list(entry_node, &acp[inst->src[i].reg % ACP_HASH_SIZE]) {
acp_entry *entry = (acp_entry *)entry_node;
if (try_constant_propagate(inst, entry))
/* kill the destination from the ACP */
if (inst->dst.file == GRF) {
- foreach_list_safe(entry_node, &acp[inst->dst.reg % acp_count]) {
+ foreach_list_safe(entry_node, &acp[inst->dst.reg % ACP_HASH_SIZE]) {
acp_entry *entry = (acp_entry *)entry_node;
if (inst->overwrites_reg(entry->dst)) {
/* Oops, we only have the chaining hash based on the destination, not
* the source, so walk across the entire table.
*/
- for (int i = 0; i < acp_count; i++) {
+ for (int i = 0; i < ACP_HASH_SIZE; i++) {
foreach_list_safe(entry_node, &acp[i]) {
acp_entry *entry = (acp_entry *)entry_node;
if (inst->overwrites_reg(entry->src))
acp_entry *entry = ralloc(mem_ctx, acp_entry);
entry->dst = inst->dst;
entry->src = inst->src[0];
- acp[entry->dst.reg % acp_count].push_tail(entry);
+ acp[entry->dst.reg % ACP_HASH_SIZE].push_tail(entry);
}
}
{
bool progress = false;
void *mem_ctx = ralloc_context(this->mem_ctx);
-
cfg_t cfg(this);
+ exec_list out_acp[cfg.num_blocks][ACP_HASH_SIZE];
+ /* First, walk through each block doing local copy propagation and getting
+ * the set of copies available at the end of the block.
+ */
for (int b = 0; b < cfg.num_blocks; b++) {
bblock_t *block = cfg.blocks[b];
- progress = opt_copy_propagate_local(mem_ctx, block) || progress;
+ progress = opt_copy_propagate_local(mem_ctx, block,
+ out_acp[b]) || progress;
+ }
+
+ /* Do dataflow analysis for those available copies. */
+ fs_copy_prop_dataflow dataflow(mem_ctx, &cfg, out_acp);
+
+ /* Next, re-run local copy propagation, this time with the set of copies
+ * provided by the dataflow analysis available at the start of a block.
+ */
+ for (int b = 0; b < cfg.num_blocks; b++) {
+ bblock_t *block = cfg.blocks[b];
+ exec_list in_acp[ACP_HASH_SIZE];
+
+ for (int i = 0; i < dataflow.num_acp; i++) {
+ if (dataflow.bd[b].livein[i]) {
+ struct acp_entry *entry = dataflow.acp[i];
+ in_acp[entry->dst.reg % ACP_HASH_SIZE].push_tail(entry);
+ }
+ }
+
+ progress = opt_copy_propagate_local(mem_ctx, block, in_acp) || progress;
}
ralloc_free(mem_ctx);
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