mirror of https://gitlab.com/qemu-project/qemu
Add copy and constant propagation.
Make tcg_constant_folding do copy and constant propagation. It is a preparational work before actual constant folding. Signed-off-by: Kirill Batuzov <batuzovk@ispras.ru> Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
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8f2e8c07a6
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22613af4a6
182
tcg/optimize.c
182
tcg/optimize.c
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@ -40,24 +40,196 @@
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glue(glue(case INDEX_op_, x), _i32)
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glue(glue(case INDEX_op_, x), _i32)
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#endif
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#endif
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typedef enum {
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TCG_TEMP_UNDEF = 0,
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TCG_TEMP_CONST,
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TCG_TEMP_COPY,
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TCG_TEMP_HAS_COPY,
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TCG_TEMP_ANY
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} tcg_temp_state;
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struct tcg_temp_info {
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tcg_temp_state state;
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uint16_t prev_copy;
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uint16_t next_copy;
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tcg_target_ulong val;
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};
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static struct tcg_temp_info temps[TCG_MAX_TEMPS];
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/* Reset TEMP's state to TCG_TEMP_ANY. If TEMP was a representative of some
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class of equivalent temp's, a new representative should be chosen in this
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class. */
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static void reset_temp(TCGArg temp, int nb_temps, int nb_globals)
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{
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int i;
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TCGArg new_base = (TCGArg)-1;
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if (temps[temp].state == TCG_TEMP_HAS_COPY) {
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for (i = temps[temp].next_copy; i != temp; i = temps[i].next_copy) {
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if (i >= nb_globals) {
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temps[i].state = TCG_TEMP_HAS_COPY;
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new_base = i;
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break;
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}
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}
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for (i = temps[temp].next_copy; i != temp; i = temps[i].next_copy) {
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if (new_base == (TCGArg)-1) {
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temps[i].state = TCG_TEMP_ANY;
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} else {
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temps[i].val = new_base;
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}
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}
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temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy;
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temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy;
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} else if (temps[temp].state == TCG_TEMP_COPY) {
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temps[temps[temp].next_copy].prev_copy = temps[temp].prev_copy;
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temps[temps[temp].prev_copy].next_copy = temps[temp].next_copy;
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new_base = temps[temp].val;
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}
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temps[temp].state = TCG_TEMP_ANY;
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if (new_base != (TCGArg)-1 && temps[new_base].next_copy == new_base) {
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temps[new_base].state = TCG_TEMP_ANY;
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}
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}
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static int op_bits(int op)
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{
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switch (op) {
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case INDEX_op_mov_i32:
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return 32;
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#if TCG_TARGET_REG_BITS == 64
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case INDEX_op_mov_i64:
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return 64;
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#endif
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default:
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fprintf(stderr, "Unrecognized operation %d in op_bits.\n", op);
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tcg_abort();
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}
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}
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static int op_to_movi(int op)
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{
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switch (op_bits(op)) {
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case 32:
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return INDEX_op_movi_i32;
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#if TCG_TARGET_REG_BITS == 64
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case 64:
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return INDEX_op_movi_i64;
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#endif
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default:
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fprintf(stderr, "op_to_movi: unexpected return value of "
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"function op_bits.\n");
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tcg_abort();
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}
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}
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static void tcg_opt_gen_mov(TCGArg *gen_args, TCGArg dst, TCGArg src,
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int nb_temps, int nb_globals)
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{
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reset_temp(dst, nb_temps, nb_globals);
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assert(temps[src].state != TCG_TEMP_COPY);
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if (src >= nb_globals) {
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assert(temps[src].state != TCG_TEMP_CONST);
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if (temps[src].state != TCG_TEMP_HAS_COPY) {
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temps[src].state = TCG_TEMP_HAS_COPY;
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temps[src].next_copy = src;
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temps[src].prev_copy = src;
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}
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temps[dst].state = TCG_TEMP_COPY;
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temps[dst].val = src;
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temps[dst].next_copy = temps[src].next_copy;
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temps[dst].prev_copy = src;
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temps[temps[dst].next_copy].prev_copy = dst;
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temps[src].next_copy = dst;
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}
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gen_args[0] = dst;
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gen_args[1] = src;
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}
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static void tcg_opt_gen_movi(TCGArg *gen_args, TCGArg dst, TCGArg val,
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int nb_temps, int nb_globals)
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{
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reset_temp(dst, nb_temps, nb_globals);
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temps[dst].state = TCG_TEMP_CONST;
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temps[dst].val = val;
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gen_args[0] = dst;
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gen_args[1] = val;
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}
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/* Propagate constants and copies, fold constant expressions. */
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static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
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static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
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TCGArg *args, TCGOpDef *tcg_op_defs)
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TCGArg *args, TCGOpDef *tcg_op_defs)
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{
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{
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int i, nb_ops, op_index, op, nb_temps, nb_globals;
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int i, nb_ops, op_index, op, nb_temps, nb_globals, nb_call_args;
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const TCGOpDef *def;
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const TCGOpDef *def;
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TCGArg *gen_args;
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TCGArg *gen_args;
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/* Array VALS has an element for each temp.
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If this temp holds a constant then its value is kept in VALS' element.
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If this temp is a copy of other ones then this equivalence class'
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representative is kept in VALS' element.
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If this temp is neither copy nor constant then corresponding VALS'
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element is unused. */
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nb_temps = s->nb_temps;
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nb_temps = s->nb_temps;
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nb_globals = s->nb_globals;
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nb_globals = s->nb_globals;
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memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
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nb_ops = tcg_opc_ptr - gen_opc_buf;
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nb_ops = tcg_opc_ptr - gen_opc_buf;
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gen_args = args;
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gen_args = args;
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for (op_index = 0; op_index < nb_ops; op_index++) {
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for (op_index = 0; op_index < nb_ops; op_index++) {
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op = gen_opc_buf[op_index];
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op = gen_opc_buf[op_index];
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def = &tcg_op_defs[op];
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def = &tcg_op_defs[op];
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/* Do copy propagation */
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if (!(def->flags & (TCG_OPF_CALL_CLOBBER | TCG_OPF_SIDE_EFFECTS))) {
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assert(op != INDEX_op_call);
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for (i = def->nb_oargs; i < def->nb_oargs + def->nb_iargs; i++) {
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if (temps[args[i]].state == TCG_TEMP_COPY) {
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args[i] = temps[args[i]].val;
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}
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}
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}
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/* Propagate constants through copy operations and do constant
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folding. Constants will be substituted to arguments by register
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allocator where needed and possible. Also detect copies. */
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switch (op) {
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switch (op) {
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CASE_OP_32_64(mov):
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if ((temps[args[1]].state == TCG_TEMP_COPY
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&& temps[args[1]].val == args[0])
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|| args[0] == args[1]) {
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args += 2;
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gen_opc_buf[op_index] = INDEX_op_nop;
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break;
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}
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if (temps[args[1]].state != TCG_TEMP_CONST) {
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tcg_opt_gen_mov(gen_args, args[0], args[1],
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nb_temps, nb_globals);
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gen_args += 2;
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args += 2;
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break;
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}
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/* Source argument is constant. Rewrite the operation and
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let movi case handle it. */
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op = op_to_movi(op);
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gen_opc_buf[op_index] = op;
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args[1] = temps[args[1]].val;
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/* fallthrough */
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CASE_OP_32_64(movi):
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tcg_opt_gen_movi(gen_args, args[0], args[1], nb_temps, nb_globals);
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gen_args += 2;
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args += 2;
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break;
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case INDEX_op_call:
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case INDEX_op_call:
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i = (args[0] >> 16) + (args[0] & 0xffff) + 3;
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nb_call_args = (args[0] >> 16) + (args[0] & 0xffff);
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if (!(args[nb_call_args + 1] & (TCG_CALL_CONST | TCG_CALL_PURE))) {
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for (i = 0; i < nb_globals; i++) {
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reset_temp(i, nb_temps, nb_globals);
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}
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}
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for (i = 0; i < (args[0] >> 16); i++) {
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reset_temp(args[i + 1], nb_temps, nb_globals);
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}
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i = nb_call_args + 3;
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while (i) {
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while (i) {
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*gen_args = *args;
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*gen_args = *args;
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args++;
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args++;
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@ -69,6 +241,7 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
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case INDEX_op_jmp:
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case INDEX_op_jmp:
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case INDEX_op_br:
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case INDEX_op_br:
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CASE_OP_32_64(brcond):
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CASE_OP_32_64(brcond):
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memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
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for (i = 0; i < def->nb_args; i++) {
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for (i = 0; i < def->nb_args; i++) {
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*gen_args = *args;
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*gen_args = *args;
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args++;
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args++;
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@ -76,6 +249,11 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
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}
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}
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break;
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break;
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default:
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default:
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/* Default case: we do know nothing about operation so no
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propagation is done. We only trash output args. */
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for (i = 0; i < def->nb_oargs; i++) {
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reset_temp(args[i], nb_temps, nb_globals);
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}
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for (i = 0; i < def->nb_args; i++) {
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for (i = 0; i < def->nb_args; i++) {
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gen_args[i] = args[i];
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gen_args[i] = args[i];
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}
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}
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