diff options
| -rw-r--r-- | tcg/optimize.c | 182 |
1 files changed, 180 insertions, 2 deletions
diff --git a/tcg/optimize.c b/tcg/optimize.c index c7c7da9..f8afe71 100644 --- a/tcg/optimize.c +++ b/tcg/optimize.c @@ -40,24 +40,196 @@ glue(glue(case INDEX_op_, x), _i32) #endif +typedef enum { + TCG_TEMP_UNDEF = 0, + TCG_TEMP_CONST, + TCG_TEMP_COPY, + TCG_TEMP_HAS_COPY, + TCG_TEMP_ANY +} tcg_temp_state; + +struct tcg_temp_info { + tcg_temp_state state; + uint16_t prev_copy; + uint16_t next_copy; + tcg_target_ulong val; +}; + +static struct tcg_temp_info temps[TCG_MAX_TEMPS]; + +/* Reset TEMP's state to TCG_TEMP_ANY. If TEMP was a representative of some + class of equivalent temp's, a new representative should be chosen in this + class. */ +static void reset_temp(TCGArg temp, int nb_temps, int nb_globals) +{ + int i; + TCGArg new_base = (TCGArg)-1; + if (temps[temp].state == TCG_TEMP_HAS_COPY) { + for (i = temps[temp].next_copy; i != temp; i = temps[i].next_copy) { + if (i >= nb_globals) { + temps[i].state = TCG_TEMP_HAS_COPY; + new_base = i; + break; + } + } + for (i = temps[temp].next_copy; i != temp; i = temps[i].next_copy) { + if (new_base == (TCGArg)-1) { + temps[i].state = TCG_TEMP_ANY; + } else { + temps[i].val = new_base; + } + } + temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy; + temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy; + } else if (temps[temp].state == TCG_TEMP_COPY) { + temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy; + temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy; + new_base = temps[temp].val; + } + temps[temp].state = TCG_TEMP_ANY; + if (new_base != (TCGArg)-1 && temps[new_base].next_copy == new_base) { + temps[new_base].state = TCG_TEMP_ANY; + } +} + +static int op_bits(int op) +{ + switch (op) { + case INDEX_op_mov_i32: + return 32; +#if TCG_TARGET_REG_BITS == 64 + case INDEX_op_mov_i64: + return 64; +#endif + default: + fprintf(stderr, "Unrecognized operation %d in op_bits.\n", op); + tcg_abort(); + } +} + +static int op_to_movi(int op) +{ + switch (op_bits(op)) { + case 32: + return INDEX_op_movi_i32; +#if TCG_TARGET_REG_BITS == 64 + case 64: + return INDEX_op_movi_i64; +#endif + default: + fprintf(stderr, "op_to_movi: unexpected return value of " + "function op_bits.\n"); + tcg_abort(); + } +} + +static void tcg_opt_gen_mov(TCGArg *gen_args, TCGArg dst, TCGArg src, + int nb_temps, int nb_globals) +{ + reset_temp(dst, nb_temps, nb_globals); + assert(temps[src].state != TCG_TEMP_COPY); + if (src >= nb_globals) { + assert(temps[src].state != TCG_TEMP_CONST); + if (temps[src].state != TCG_TEMP_HAS_COPY) { + temps[src].state = TCG_TEMP_HAS_COPY; + temps[src].next_copy = src; + temps[src].prev_copy = src; + } + temps[dst].state = TCG_TEMP_COPY; + temps[dst].val = src; + temps[dst].next_copy = temps[src].next_copy; + temps[dst].prev_copy = src; + temps[temps[dst].next_copy].prev_copy = dst; + temps[src].next_copy = dst; + } + gen_args[0] = dst; + gen_args[1] = src; +} + +static void tcg_opt_gen_movi(TCGArg *gen_args, TCGArg dst, TCGArg val, + int nb_temps, int nb_globals) +{ + reset_temp(dst, nb_temps, nb_globals); + temps[dst].state = TCG_TEMP_CONST; + temps[dst].val = val; + gen_args[0] = dst; + gen_args[1] = val; +} + +/* Propagate constants and copies, fold constant expressions. */ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr, TCGArg *args, TCGOpDef *tcg_op_defs) { - int i, nb_ops, op_index, op, nb_temps, nb_globals; + int i, nb_ops, op_index, op, nb_temps, nb_globals, nb_call_args; const TCGOpDef *def; TCGArg *gen_args; + /* Array VALS has an element for each temp. + If this temp holds a constant then its value is kept in VALS' element. + If this temp is a copy of other ones then this equivalence class' + representative is kept in VALS' element. + If this temp is neither copy nor constant then corresponding VALS' + element is unused. */ nb_temps = s->nb_temps; nb_globals = s->nb_globals; + memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info)); nb_ops = tcg_opc_ptr - gen_opc_buf; gen_args = args; for (op_index = 0; op_index < nb_ops; op_index++) { op = gen_opc_buf[op_index]; def = &tcg_op_defs[op]; + /* Do copy propagation */ + if (!(def->flags & (TCG_OPF_CALL_CLOBBER | TCG_OPF_SIDE_EFFECTS))) { + assert(op != INDEX_op_call); + for (i = def->nb_oargs; i < def->nb_oargs + def->nb_iargs; i++) { + if (temps[args[i]].state == TCG_TEMP_COPY) { + args[i] = temps[args[i]].val; + } + } + } + + /* Propagate constants through copy operations and do constant + folding. Constants will be substituted to arguments by register + allocator where needed and possible. Also detect copies. */ switch (op) { + CASE_OP_32_64(mov): + if ((temps[args[1]].state == TCG_TEMP_COPY + && temps[args[1]].val == args[0]) + || args[0] == args[1]) { + args += 2; + gen_opc_buf[op_index] = INDEX_op_nop; + break; + } + if (temps[args[1]].state != TCG_TEMP_CONST) { + tcg_opt_gen_mov(gen_args, args[0], args[1], + nb_temps, nb_globals); + gen_args += 2; + args += 2; + break; + } + /* Source argument is constant. Rewrite the operation and + let movi case handle it. */ + op = op_to_movi(op); + gen_opc_buf[op_index] = op; + args[1] = temps[args[1]].val; + /* fallthrough */ + CASE_OP_32_64(movi): + tcg_opt_gen_movi(gen_args, args[0], args[1], nb_temps, nb_globals); + gen_args += 2; + args += 2; + break; case INDEX_op_call: - i = (args[0] >> 16) + (args[0] & 0xffff) + 3; + nb_call_args = (args[0] >> 16) + (args[0] & 0xffff); + if (!(args[nb_call_args + 1] & (TCG_CALL_CONST | TCG_CALL_PURE))) { + for (i = 0; i < nb_globals; i++) { + reset_temp(i, nb_temps, nb_globals); + } + } + for (i = 0; i < (args[0] >> 16); i++) { + reset_temp(args[i + 1], nb_temps, nb_globals); + } + i = nb_call_args + 3; while (i) { *gen_args = *args; args++; @@ -69,6 +241,7 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr, case INDEX_op_jmp: case INDEX_op_br: CASE_OP_32_64(brcond): + memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info)); for (i = 0; i < def->nb_args; i++) { *gen_args = *args; args++; @@ -76,6 +249,11 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr, } break; default: + /* Default case: we do know nothing about operation so no + propagation is done. We only trash output args. */ + for (i = 0; i < def->nb_oargs; i++) { + reset_temp(args[i], nb_temps, nb_globals); + } for (i = 0; i < def->nb_args; i++) { gen_args[i] = args[i]; } |