diff options
| -rw-r--r-- | src/mesa/drivers/dri/i965/brw_fs.cpp | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp index 472e6d06f6..5eaa998447 100644 --- a/src/mesa/drivers/dri/i965/brw_fs.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp @@ -455,6 +455,7 @@ public: void assign_regs(); void assign_regs_trivial(); void calculate_live_intervals(); + bool propagate_constants(); bool dead_code_eliminate(); bool virtual_grf_interferes(int a, int b); void generate_code(); @@ -2523,6 +2524,94 @@ fs_visitor::calculate_live_intervals() } /** + * Attempts to move immediate constants into the immediate + * constant slot of following instructions. + * + * Immediate constants are a bit tricky -- they have to be in the last + * operand slot, you can't do abs/negate on them, + */ + +bool +fs_visitor::propagate_constants() +{ + bool progress = false; + + return false; + + foreach_iter(exec_list_iterator, iter, this->instructions) { + fs_inst *inst = (fs_inst *)iter.get(); + + if (inst->opcode != BRW_OPCODE_MOV || + inst->predicated || + inst->dst.file != GRF || inst->src[0].file != IMM || + inst->dst.type != inst->src[0].type) + continue; + + /* Don't bother with cases where we should have had the + * operation on the constant folded in GLSL already. + */ + if (inst->saturate) + continue; + + /* Found a move of a constant to a GRF. Find anything else using the GRF + * before it's written, and replace it with the constant if we can. + */ + exec_list_iterator scan_iter = iter; + scan_iter.next(); + for (; scan_iter.has_next(); scan_iter.next()) { + fs_inst *scan_inst = (fs_inst *)scan_iter.get(); + + if (scan_inst->opcode == BRW_OPCODE_DO || + scan_inst->opcode == BRW_OPCODE_WHILE || + scan_inst->opcode == BRW_OPCODE_ELSE || + scan_inst->opcode == BRW_OPCODE_ENDIF) { + break; + } + + for (int i = 2; i >= 0; i--) { + if (scan_inst->src[i].file != GRF || + scan_inst->src[i].reg != inst->dst.reg || + scan_inst->src[i].reg_offset != inst->dst.reg_offset) + continue; + + /* Don't bother with cases where we should have had the + * operation on the constant folded in GLSL already. + */ + if (scan_inst->src[i].negate || scan_inst->src[i].abs) + continue; + + switch (scan_inst->opcode) { + case BRW_OPCODE_MOV: + scan_inst->src[i] = inst->src[0]; + progress = true; + break; + + case BRW_OPCODE_MUL: + case BRW_OPCODE_ADD: + if (i == 1) { + scan_inst->src[i] = inst->src[0]; + progress = true; + } else if (i == 0 && scan_inst->src[1].file != IMM) { + /* Fit this constant in by commuting the operands */ + scan_inst->src[0] = scan_inst->src[1]; + scan_inst->src[1] = inst->src[0]; + } + break; + } + } + + if (scan_inst->dst.file == GRF && + scan_inst->dst.reg == inst->dst.reg && + (scan_inst->dst.reg_offset == inst->dst.reg_offset || + scan_inst->opcode == FS_OPCODE_TEX)) { + break; + } + } + } + + return progress; +} +/** * Must be called after calculate_live_intervales() to remove unused * writes to registers -- register allocation will fail otherwise * because something deffed but not used won't be considered to @@ -2876,6 +2965,7 @@ brw_wm_fs_emit(struct brw_context *brw, struct brw_wm_compile *c) progress = false; v.calculate_live_intervals(); + progress = v.propagate_constants() || progress; progress = v.dead_code_eliminate() || progress; } while (progress); |