#include "brw_cfg.h"
/** @file brw_fs_saturate_propagation.cpp
+ *
+ * Implements a pass that propagates the SAT modifier from a MOV.SAT into the
+ * instruction that produced the source of the MOV.SAT, thereby allowing the
+ * MOV's src and dst to be coalesced and the MOV removed.
+ *
+ * For instance,
+ *
+ * ADD tmp, src0, src1
+ * MOV.SAT dst, tmp
+ *
+ * would be transformed into
+ *
+ * ADD.SAT tmp, src0, src1
+ * MOV dst, tmp
*/
static bool
opt_saturate_propagation_local(fs_visitor *v, bblock_t *block)
{
bool progress = false;
- int ip = block->start_ip - 1;
+ int ip = block->end_ip + 1;
- foreach_inst_in_block(fs_inst, inst, block) {
- ip++;
+ foreach_inst_in_block_reverse(fs_inst, inst, block) {
+ ip--;
if (inst->opcode != BRW_OPCODE_MOV ||
inst->dst.file != GRF ||
!inst->saturate)
continue;
- int src_var = v->live_intervals->var_from_reg(&inst->src[0]);
+ int src_var = v->live_intervals->var_from_reg(inst->src[0]);
int src_end_ip = v->live_intervals->end[src_var];
- int scan_ip = ip;
bool interfered = false;
- for (fs_inst *scan_inst = (fs_inst *) inst->prev;
- scan_inst != block->start->prev;
- scan_inst = (fs_inst *) scan_inst->prev) {
- scan_ip--;
+ foreach_inst_in_block_reverse_starting_from(fs_inst, scan_inst, inst, block) {
+ if (scan_inst->overwrites_reg(inst->src[0])) {
+ if (scan_inst->is_partial_write())
+ break;
- if (scan_inst->dst.file == GRF &&
- scan_inst->dst.reg == inst->src[0].reg &&
- scan_inst->dst.reg_offset == inst->src[0].reg_offset &&
- !scan_inst->is_partial_write()) {
if (scan_inst->saturate) {
inst->saturate = false;
progress = true;
if (scan_inst->src[i].file == GRF &&
scan_inst->src[i].reg == inst->src[0].reg &&
scan_inst->src[i].reg_offset == inst->src[0].reg_offset) {
- interfered = true;
- break;
+ if (scan_inst->opcode != BRW_OPCODE_MOV ||
+ !scan_inst->saturate ||
+ scan_inst->src[0].abs ||
+ scan_inst->src[0].negate) {
+ interfered = true;
+ break;
+ }
}
}
{
bool progress = false;
- cfg_t cfg(&instructions);
-
- calculate_live_intervals(&cfg);
+ calculate_live_intervals();
- for (int b = 0; b < cfg.num_blocks; b++) {
- progress = opt_saturate_propagation_local(this, cfg.blocks[b])
- || progress;
+ foreach_block (block, cfg) {
+ progress = opt_saturate_propagation_local(this, block) || progress;
}
- if (progress)
- invalidate_live_intervals();
+ /* Live intervals are still valid. */
return progress;
}