tcg.c

来自「xen虚拟机源代码安装包」· C语言 代码 · 共 1,895 行 · 第 1/4 页

            nb_args = args[-1];
            args -= nb_args;
            nb_iargs = args[0] & 0xffff;
            nb_oargs = args[0] >> 16;
            args++;

            /* output args are dead */
            for(i = 0; i < nb_oargs; i++) {
                arg = args[i];
                dead_temps[arg] = 1;
            }
            
            /* globals are live (they may be used by the call) */
            memset(dead_temps, 0, s->nb_globals);

            /* input args are live */
            dead_iargs = 0;
            for(i = 0; i < nb_iargs; i++) {
                arg = args[i + nb_oargs];
                if (dead_temps[arg]) {
                    dead_iargs |= (1 << i);
                }
                dead_temps[arg] = 0;
            }
            s->op_dead_iargs[op_index] = dead_iargs;
            args--;
            break;
        case INDEX_op_set_label:
            args--;
            /* mark end of basic block */
            tcg_la_bb_end(s, dead_temps);
            break;
        case INDEX_op_nopn:
            nb_args = args[-1];
            args -= nb_args;
            break;
        case INDEX_op_discard:
            args--;
            /* mark the temporary as dead */
            dead_temps[args[0]] = 1;
            break;
        case INDEX_op_macro_2:
            {
                int dead_args[2], macro_id;
                int saved_op_index, saved_arg_index;
                int macro_op_index, macro_arg_index;
                int macro_end_op_index, macro_end_arg_index;
                int last_nb_temps;
                
                nb_args = 3;
                args -= nb_args;
                dead_args[0] = dead_temps[args[0]];
                dead_args[1] = dead_temps[args[1]];
                macro_id = args[2];

                /* call the macro function which generate code
                   depending on the live outputs */
                saved_op_index = op_index;
                saved_arg_index = args - gen_opparam_buf;

                /* add a macro start instruction */
                *gen_opc_ptr++ = INDEX_op_macro_start;
                *gen_opparam_ptr++ = saved_op_index;
                *gen_opparam_ptr++ = saved_arg_index;

                macro_op_index = gen_opc_ptr - gen_opc_buf;
                macro_arg_index = gen_opparam_ptr -  gen_opparam_buf;

                last_nb_temps = s->nb_temps;

                s->macro_func(s, macro_id, dead_args);

                /* realloc temp info (XXX: make it faster) */
                if (s->nb_temps > last_nb_temps) {
                    uint8_t *new_dead_temps;

                    new_dead_temps = tcg_malloc(s->nb_temps);
                    memcpy(new_dead_temps, dead_temps, last_nb_temps);
                    memset(new_dead_temps + last_nb_temps, 1, 
                           s->nb_temps - last_nb_temps);
                    dead_temps = new_dead_temps;
                }

                macro_end_op_index = gen_opc_ptr - gen_opc_buf;
                macro_end_arg_index = gen_opparam_ptr - gen_opparam_buf;

                /* end of macro: add a goto to the next instruction */
                *gen_opc_ptr++ = INDEX_op_macro_end;
                *gen_opparam_ptr++ = op_index + 1;
                *gen_opparam_ptr++ = saved_arg_index + nb_args;

                /* modify the macro operation to be a macro_goto */
                gen_opc_buf[op_index] = INDEX_op_macro_goto;
                args[0] = macro_op_index;
                args[1] = macro_arg_index;
                args[2] = 0; /* dummy third arg to match the 
                                macro parameters */

                /* set the next instruction to the end of the macro */
                op_index = macro_end_op_index;
                args = macro_end_arg_index + gen_opparam_buf;
            }
            break;
        case INDEX_op_macro_start:
            args -= 2;
            op_index = args[0];
            args = gen_opparam_buf + args[1];
            break;
        case INDEX_op_macro_goto:
        case INDEX_op_macro_end:
            tcg_abort(); /* should never happen in liveness analysis */
        case INDEX_op_end:
            break;
            /* XXX: optimize by hardcoding common cases (e.g. triadic ops) */
        default:
            if (op > INDEX_op_end) {
                args -= def->nb_args;
                nb_iargs = def->nb_iargs;
                nb_oargs = def->nb_oargs;

                /* Test if the operation can be removed because all
                   its outputs are dead. We assume that nb_oargs == 0
                   implies side effects */
                if (!(def->flags & TCG_OPF_SIDE_EFFECTS) && nb_oargs != 0) {
                    for(i = 0; i < nb_oargs; i++) {
                        arg = args[i];
                        if (!dead_temps[arg])
                            goto do_not_remove;
                    }
                    tcg_set_nop(s, gen_opc_buf + op_index, args, def->nb_args);
#ifdef CONFIG_PROFILER
                    {
                        extern int64_t dyngen_tcg_del_op_count;
                        dyngen_tcg_del_op_count++;
                    }
#endif
                } else {
                do_not_remove:

                    /* output args are dead */
                    for(i = 0; i < nb_oargs; i++) {
                        arg = args[i];
                        dead_temps[arg] = 1;
                    }
                    
                    /* if end of basic block, update */
                    if (def->flags & TCG_OPF_BB_END) {
                        tcg_la_bb_end(s, dead_temps);
                    } else if (def->flags & TCG_OPF_CALL_CLOBBER) {
                        /* globals are live */
                        memset(dead_temps, 0, s->nb_globals);
                    }
                    
                    /* input args are live */
                    dead_iargs = 0;
                    for(i = 0; i < nb_iargs; i++) {
                        arg = args[i + nb_oargs];
                        if (dead_temps[arg]) {
                            dead_iargs |= (1 << i);
                        }
                        dead_temps[arg] = 0;
                    }
                    s->op_dead_iargs[op_index] = dead_iargs;
                }
            } else {
                /* legacy dyngen operations */
                args -= def->nb_args;
                /* mark end of basic block */
                tcg_la_bb_end(s, dead_temps);
            }
            break;
        }
        op_index--;
    }

    if (args != gen_opparam_buf)
        tcg_abort();
}
#else
/* dummy liveness analysis */
void tcg_liveness_analysis(TCGContext *s)
{
    int nb_ops;
    nb_ops = gen_opc_ptr - gen_opc_buf;

    s->op_dead_iargs = tcg_malloc(nb_ops * sizeof(uint16_t));
    memset(s->op_dead_iargs, 0, nb_ops * sizeof(uint16_t));
}
#endif

#ifndef NDEBUG
static void dump_regs(TCGContext *s)
{
    TCGTemp *ts;
    int i;
    char buf[64];

    for(i = 0; i < s->nb_temps; i++) {
        ts = &s->temps[i];
        printf("  %10s: ", tcg_get_arg_str_idx(s, buf, sizeof(buf), i));
        switch(ts->val_type) {
        case TEMP_VAL_REG:
            printf("%s", tcg_target_reg_names[ts->reg]);
            break;
        case TEMP_VAL_MEM:
            printf("%d(%s)", (int)ts->mem_offset, tcg_target_reg_names[ts->mem_reg]);
            break;
        case TEMP_VAL_CONST:
            printf("$0x%" TCG_PRIlx, ts->val);
            break;
        case TEMP_VAL_DEAD:
            printf("D");
            break;
        default:
            printf("???");
            break;
        }
        printf("\n");
    }

    for(i = 0; i < TCG_TARGET_NB_REGS; i++) {
        if (s->reg_to_temp[i] >= 0) {
            printf("%s: %s\n", 
                   tcg_target_reg_names[i], 
                   tcg_get_arg_str_idx(s, buf, sizeof(buf), s->reg_to_temp[i]));
        }
    }
}

static void check_regs(TCGContext *s)
{
    int reg, k;
    TCGTemp *ts;
    char buf[64];

    for(reg = 0; reg < TCG_TARGET_NB_REGS; reg++) {
        k = s->reg_to_temp[reg];
        if (k >= 0) {
            ts = &s->temps[k];
            if (ts->val_type != TEMP_VAL_REG ||
                ts->reg != reg) {
                printf("Inconsistency for register %s:\n", 
                       tcg_target_reg_names[reg]);
                goto fail;
            }
        }
    }
    for(k = 0; k < s->nb_temps; k++) {
        ts = &s->temps[k];
        if (ts->val_type == TEMP_VAL_REG &&
            !ts->fixed_reg &&
            s->reg_to_temp[ts->reg] != k) {
                printf("Inconsistency for temp %s:\n", 
                       tcg_get_arg_str_idx(s, buf, sizeof(buf), k));
        fail:
                printf("reg state:\n");
                dump_regs(s);
                tcg_abort();
        }
        if (ts->val_type == TEMP_VAL_CONST && k < s->nb_globals) {
            printf("constant forbidden in global %s\n",
                   tcg_get_arg_str_idx(s, buf, sizeof(buf), k));
            goto fail;
        }
    }
}
#endif

static void temp_allocate_frame(TCGContext *s, int temp)
{
    TCGTemp *ts;
    ts = &s->temps[temp];
    s->current_frame_offset = (s->current_frame_offset + sizeof(tcg_target_long) - 1) & ~(sizeof(tcg_target_long) - 1);
    if (s->current_frame_offset + sizeof(tcg_target_long) > s->frame_end)
        tcg_abort();
    ts->mem_offset = s->current_frame_offset;
    ts->mem_reg = s->frame_reg;
    ts->mem_allocated = 1;
    s->current_frame_offset += sizeof(tcg_target_long);
}

/* free register 'reg' by spilling the corresponding temporary if necessary */
static void tcg_reg_free(TCGContext *s, int reg)
{
    TCGTemp *ts;
    int temp;

    temp = s->reg_to_temp[reg];
    if (temp != -1) {
        ts = &s->temps[temp];
        assert(ts->val_type == TEMP_VAL_REG);
        if (!ts->mem_coherent) {
            if (!ts->mem_allocated) 
                temp_allocate_frame(s, temp);
            tcg_out_st(s, ts->type, reg, ts->mem_reg, ts->mem_offset);
        }
        ts->val_type = TEMP_VAL_MEM;
        s->reg_to_temp[reg] = -1;
    }
}

/* Allocate a register belonging to reg1 & ~reg2 */
static int tcg_reg_alloc(TCGContext *s, TCGRegSet reg1, TCGRegSet reg2)
{
    int i, reg;
    TCGRegSet reg_ct;

    tcg_regset_andnot(reg_ct, reg1, reg2);

    /* first try free registers */
    for(i = 0; i < ARRAY_SIZE(tcg_target_reg_alloc_order); i++) {
        reg = tcg_target_reg_alloc_order[i];
        if (tcg_regset_test_reg(reg_ct, reg) && s->reg_to_temp[reg] == -1)
            return reg;
    }

    /* XXX: do better spill choice */
    for(i = 0; i < ARRAY_SIZE(tcg_target_reg_alloc_order); i++) {
        reg = tcg_target_reg_alloc_order[i];
        if (tcg_regset_test_reg(reg_ct, reg)) {
            tcg_reg_free(s, reg);
            return reg;
        }
    }

    tcg_abort();
}

/* at the end of a basic block, we assume all temporaries are dead and
   all globals are stored at their canonical location */
/* XXX: optimize by handling constants in another array ? */
void tcg_reg_alloc_bb_end(TCGContext *s)
{
    TCGTemp *ts;
    int i;

    for(i = 0; i < s->nb_globals; i++) {
        ts = &s->temps[i];
        if (!ts->fixed_reg) {
            if (ts->val_type == TEMP_VAL_REG) {
                tcg_reg_free(s, ts->reg);
            }
        }
    }

    for(i = s->nb_globals; i < s->nb_temps; i++) {
        ts = &s->temps[i];
        if (ts->val_type != TEMP_VAL_CONST) {
            if (ts->val_type == TEMP_VAL_REG) {
                s->reg_to_temp[ts->reg] = -1;
            }
            ts->val_type = TEMP_VAL_DEAD;
        }
    }
}

#define IS_DEAD_IARG(n) ((dead_iargs >> (n)) & 1)

static void tcg_reg_alloc_mov(TCGContext *s, const TCGOpDef *def,
                              const TCGArg *args,
                              unsigned int dead_iargs)
{
    TCGTemp *ts, *ots;
    int reg;
    const TCGArgConstraint *arg_ct;

    ots = &s->temps[args[0]];
    ts = &s->temps[args[1]];
    arg_ct = &def->args_ct[0];

    if (ts->val_type == TEMP_VAL_REG) {
        if (IS_DEAD_IARG(0) && !ts->fixed_reg && !ots->fixed_reg) {
            /* the mov can be suppressed */
            if (ots->val_type == TEMP_VAL_REG)
                s->reg_to_temp[ots->reg] = -1;
            reg = ts->reg;
            s->reg_to_temp[reg] = -1;
            ts->val_type = TEMP_VAL_DEAD;
        } else {
            if (ots->val_type == TEMP_VAL_REG) {
                reg = ots->reg;
            } else {
                reg = tcg_reg_alloc(s, arg_ct->u.regs, s->reserved_regs);
            }
            if (ts->reg != reg) {
                tcg_out_mov(s, reg, ts->reg);
            }
        }
    } else if (ts->val_type == TEMP_VAL_MEM) {
        if (ots->val_type == TEMP_VAL_REG) {
            reg = ots->reg;
        } else {
            reg = tcg_reg_alloc(s, arg_ct->u.regs, s->reserved_regs);
        }
        tcg_out_ld(s, ts->type, reg, ts->mem_reg, ts->mem_offset);
    } else if (ts->val_type == TEMP_VAL_CONST) {
        if (ots->val_type == TEMP_VAL_REG) {
            reg = ots->reg;
        } else {
            reg = tcg_reg_alloc(s, arg_ct->u.regs, s->reserved_regs);
        }
        tcg_out_movi(s, ots->type, reg, ts->val);
    } else {
        tcg_abort();
    }
    s->reg_to_temp[reg] = args[0];
    ots->reg = reg;
    ots->val_type = TEMP_VAL_REG;
    ots->mem_coherent = 0;
}

static void tcg_reg_alloc_op(TCGContext *s, 
                             const TCGOpDef *def, int opc,
                             const TCGArg *args,
                             unsigned int dead_iargs)
{
    TCGRegSet allocated_regs;
    int i, k, nb_iargs, nb_oargs, reg;
    TCGArg arg;
    const TCGArgConstraint *arg_ct;
    TCGTemp *ts;
    TCGArg new_args[TCG_MAX_OP_ARGS];
    int const_args[TCG_MAX_OP_ARGS];

    nb_oargs = def->nb_oargs;
    nb_iargs = def->nb_iargs;

    /* copy constants */
    memcpy(new_args + nb_oargs + nb_iargs, 
           args + nb_oargs + nb_iargs, 
           sizeof(TCGArg) * def->nb_cargs);

    /* satisfy input constraints */ 
    tcg_regset_set(allocated_regs, s->reserved_regs);
    for(k = 0; k < nb_iargs; k++) {
        i = def->sorted_args[nb_oargs + k];
        arg = args[i];
        arg_ct = &def->args_ct[i];
        ts = &s->temps[arg];
        if (ts->val_type == TEMP_VAL_MEM) {
            reg = tcg_reg_alloc(s, arg_ct->u.regs, allocated_regs);
            tcg_out_ld(s, ts->type, reg, ts->mem_reg, ts->mem_offset);
            ts->val_type = TEMP_VAL_REG;
            ts->reg = reg;
            ts->mem_coherent = 1;
            s->reg_to_temp[reg] = arg;
        } else if (ts->val_type == TEMP_VAL_CONST) {
            if (tcg_target_const_match(ts->val, arg_ct)) {
                /* constant is OK for instruction */
                const_args[i] = 1;
                new_args[i] = ts->val;
                goto iarg_end;
            } else {
                /* need to move to a register*/
                reg = tcg_reg_alloc(s, arg_ct->u.regs, allocated_regs);
                tcg_out_movi(s, ts->type, reg, ts->val);
                goto iarg_end1;
            }
        }
        assert(ts->val_type == TEMP_VAL_REG);
        if (arg_ct->ct & TCG_CT_IALIAS) {
            if (ts->fixed_reg) {
                /* if fixed register, we must allocate a new register
                   if the alias is not the same register */
                if (arg != args[arg_ct->alias_index])
                    goto allocate_in_reg;
            } else {
                /* if the input is aliased to an output and if it is
                   not dead after the instruction, we must allocate
                   a new register and move it */
                if (!IS_DEAD_IARG(i - nb_oargs)) 
                    goto allocate_in_reg;
            }
        }