diff options
| -rw-r--r-- | src/mesa/drivers/dri/i965/brw_fs.cpp | 160 | ||||
| -rw-r--r-- | src/mesa/drivers/dri/i965/brw_fs.h | 1 |
2 files changed, 161 insertions, 0 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp index 09817b7058b..76ecd6958f0 100644 --- a/src/mesa/drivers/dri/i965/brw_fs.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp @@ -32,6 +32,7 @@ extern "C" { #include <sys/types.h> +#include "main/hash_table.h" #include "main/macros.h" #include "main/shaderobj.h" #include "main/uniforms.h" @@ -1823,6 +1824,164 @@ fs_visitor::dead_code_eliminate() return progress; } +struct dead_code_hash_key +{ + int vgrf; + int reg_offset; +}; + +static bool +dead_code_hash_compare(const void *a, const void *b) +{ + return memcmp(a, b, sizeof(struct dead_code_hash_key)) == 0; +} + +static void +clear_dead_code_hash(struct hash_table *ht) +{ + struct hash_entry *entry; + + hash_table_foreach(ht, entry) { + _mesa_hash_table_remove(ht, entry); + } +} + +static void +insert_dead_code_hash(struct hash_table *ht, + int vgrf, int reg_offset, fs_inst *inst) +{ + /* We don't bother freeing keys, because they'll be GCed with the ht. */ + struct dead_code_hash_key *key = ralloc(ht, struct dead_code_hash_key); + + key->vgrf = vgrf; + key->reg_offset = reg_offset; + + _mesa_hash_table_insert(ht, _mesa_hash_data(key, sizeof(*key)), key, inst); +} + +static struct hash_entry * +get_dead_code_hash_entry(struct hash_table *ht, int vgrf, int reg_offset) +{ + struct dead_code_hash_key key; + + key.vgrf = vgrf; + key.reg_offset = reg_offset; + + return _mesa_hash_table_search(ht, _mesa_hash_data(&key, sizeof(key)), &key); +} + +static void +remove_dead_code_hash(struct hash_table *ht, + int vgrf, int reg_offset) +{ + struct hash_entry *entry = get_dead_code_hash_entry(ht, vgrf, reg_offset); + if (!entry) + return; + + _mesa_hash_table_remove(ht, entry); +} + +/** + * Walks basic blocks, removing any regs that are written but not read before + * being redefined. + * + * The dead_code_eliminate() function implements a global dead code + * elimination, but it only handles the removing the last write to a register + * if it's never read. This one can handle intermediate writes, but only + * within a basic block. + */ +bool +fs_visitor::dead_code_eliminate_local() +{ + struct hash_table *ht; + bool progress = false; + + ht = _mesa_hash_table_create(mem_ctx, dead_code_hash_compare); + + foreach_list_safe(node, &this->instructions) { + fs_inst *inst = (fs_inst *)node; + + /* At a basic block, empty the HT since we don't understand dataflow + * here. + */ + if (inst->is_control_flow()) { + clear_dead_code_hash(ht); + continue; + } + + /* Clear the HT of any instructions that got read. */ + for (int i = 0; i < 3; i++) { + fs_reg src = inst->src[i]; + if (src.file != GRF) + continue; + + int read = 1; + if (inst->is_send_from_grf()) + read = virtual_grf_sizes[src.reg] - src.reg_offset; + + for (int reg_offset = src.reg_offset; + reg_offset < src.reg_offset + read; + reg_offset++) { + remove_dead_code_hash(ht, src.reg, reg_offset); + } + } + + /* Add any update of a GRF to the HT, removing a previous write if it + * wasn't read. + */ + if (inst->dst.file == GRF) { + if (inst->regs_written > 1) { + /* We don't know how to trim channels from an instruction's + * writes, so we can't incrementally remove unread channels from + * it. Just remove whatever it overwrites from the table + */ + for (int i = 0; i < inst->regs_written; i++) { + remove_dead_code_hash(ht, + inst->dst.reg, + inst->dst.reg_offset + i); + } + } else { + struct hash_entry *entry = + get_dead_code_hash_entry(ht, inst->dst.reg, + inst->dst.reg_offset); + + if (inst->is_partial_write()) { + /* For a partial write, we can't remove any previous dead code + * candidate, since we're just modifying their result, but we can + * be dead code eliminiated ourselves. + */ + if (entry) { + entry->data = inst; + } else { + insert_dead_code_hash(ht, inst->dst.reg, inst->dst.reg_offset, + inst); + } + } else { + if (entry) { + /* We're completely updating a channel, and there was a + * previous write to the channel that wasn't read. Kill it! + */ + fs_inst *inst = (fs_inst *)entry->data; + inst->remove(); + progress = true; + _mesa_hash_table_remove(ht, entry); + } + + insert_dead_code_hash(ht, inst->dst.reg, inst->dst.reg_offset, + inst); + } + } + } + } + + _mesa_hash_table_destroy(ht, NULL); + + if (progress) + live_intervals_valid = false; + + return progress; +} + /** * Implements a second type of register coalescing: This one checks if * the two regs involved in a raw move don't interfere, in which case @@ -2806,6 +2965,7 @@ fs_visitor::run() progress = opt_cse() || progress; progress = opt_copy_propagate() || progress; progress = dead_code_eliminate() || progress; + progress = dead_code_eliminate_local() || progress; progress = register_coalesce() || progress; progress = register_coalesce_2() || progress; progress = compute_to_mrf() || progress; diff --git a/src/mesa/drivers/dri/i965/brw_fs.h b/src/mesa/drivers/dri/i965/brw_fs.h index bcaa485781e..86a9ec590a4 100644 --- a/src/mesa/drivers/dri/i965/brw_fs.h +++ b/src/mesa/drivers/dri/i965/brw_fs.h @@ -329,6 +329,7 @@ public: bool register_coalesce_2(); bool compute_to_mrf(); bool dead_code_eliminate(); + bool dead_code_eliminate_local(); bool remove_dead_constants(); bool remove_duplicate_mrf_writes(); bool virtual_grf_interferes(int a, int b); |