Archipelago » qemu

/*

 * Tiny Code Generator for QEMU

 *

 * Copyright (c) 2008 Fabrice Bellard

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 */

/* define it to suppress various consistency checks (faster) */

#define NDEBUG

/* define it to use liveness analysis (better code) */

#define USE_LIVENESS_ANALYSIS

#include <assert.h>

#include <stdarg.h>

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <inttypes.h>

#ifdef _WIN32

#include <malloc.h>

#endif

#include "config.h"

#include "qemu-common.h"

/* Note: the long term plan is to reduce the dependancies on the QEMU

   CPU definitions. Currently they are used for qemu_ld/st

   instructions */

#define NO_CPU_IO_DEFS

#include "cpu.h"

#include "exec-all.h"

#include "tcg-op.h"

#include "elf.h"

static void patch_reloc(uint8_t *code_ptr, int type, 

                        tcg_target_long value, tcg_target_long addend);

TCGOpDef tcg_op_defs[] = {

#define DEF(s, n, copy_size) { #s, 0, 0, n, n, 0, copy_size },

#define DEF2(s, iargs, oargs, cargs, flags) { #s, iargs, oargs, cargs, iargs + oargs + cargs, flags, 0 },

#include "tcg-opc.h"

#undef DEF

#undef DEF2

};

TCGRegSet tcg_target_available_regs[2];

TCGRegSet tcg_target_call_clobber_regs;

/* XXX: move that inside the context */

uint16_t *gen_opc_ptr;

TCGArg *gen_opparam_ptr;

static inline void tcg_out8(TCGContext *s, uint8_t v)

{

    *s->code_ptr++ = v;

}

static inline void tcg_out16(TCGContext *s, uint16_t v)

{

    *(uint16_t *)s->code_ptr = v;

    s->code_ptr += 2;

}

static inline void tcg_out32(TCGContext *s, uint32_t v)

{

    *(uint32_t *)s->code_ptr = v;

    s->code_ptr += 4;

}

/* label relocation processing */

void tcg_out_reloc(TCGContext *s, uint8_t *code_ptr, int type, 

                   int label_index, long addend)

{

    TCGLabel *l;

    TCGRelocation *r;

    l = &s->labels[label_index];

    if (l->has_value) {

        /* FIXME: This may break relocations on RISC targets that

           modify instruction fields in place.  The caller may not have 

           written the initial value.  */

        patch_reloc(code_ptr, type, l->u.value, addend);

    } else {

        /* add a new relocation entry */

        r = tcg_malloc(sizeof(TCGRelocation));

        r->type = type;

        r->ptr = code_ptr;

        r->addend = addend;

        r->next = l->u.first_reloc;

        l->u.first_reloc = r;

    }

}

static void tcg_out_label(TCGContext *s, int label_index, 

                          tcg_target_long value)

{

    TCGLabel *l;

    TCGRelocation *r;

    l = &s->labels[label_index];

    if (l->has_value)

        tcg_abort();

    r = l->u.first_reloc;

    while (r != NULL) {

        patch_reloc(r->ptr, r->type, value, r->addend);

        r = r->next;

    }

    l->has_value = 1;

    l->u.value = value;

}

int gen_new_label(void)

{

    TCGContext *s = &tcg_ctx;

    int idx;

    TCGLabel *l;

    if (s->nb_labels >= TCG_MAX_LABELS)

        tcg_abort();

    idx = s->nb_labels++;

    l = &s->labels[idx];

    l->has_value = 0;

    l->u.first_reloc = NULL;

    return idx;

}

#include "tcg-target.c"

/* pool based memory allocation */

void *tcg_malloc_internal(TCGContext *s, int size)

{

    TCGPool *p;

    int pool_size;

    if (size > TCG_POOL_CHUNK_SIZE) {

        /* big malloc: insert a new pool (XXX: could optimize) */

        p = qemu_malloc(sizeof(TCGPool) + size);

        p->size = size;

        if (s->pool_current)

            s->pool_current->next = p;

        else

            s->pool_first = p;

        p->next = s->pool_current;

    } else {

        p = s->pool_current;

        if (!p) {

            p = s->pool_first;

            if (!p)

                goto new_pool;

        } else {

            if (!p->next) {

            new_pool:

                pool_size = TCG_POOL_CHUNK_SIZE;

                p = qemu_malloc(sizeof(TCGPool) + pool_size);

                p->size = pool_size;

                p->next = NULL;

                if (s->pool_current) 

                    s->pool_current->next = p;

                else

                    s->pool_first = p;

            } else {

                p = p->next;

            }

        }

    }

    s->pool_current = p;

    s->pool_cur = p->data + size;

    s->pool_end = p->data + p->size;

    return p->data;

}

void tcg_pool_reset(TCGContext *s)

{

    s->pool_cur = s->pool_end = NULL;

    s->pool_current = NULL;

}

/* free all the pool */

void tcg_pool_free(TCGContext *s)

{

    TCGPool *p, *p1;

    for(p = s->pool_first; p != NULL; p = p1) {

        p1 = p->next;

        qemu_free(p);

    }

    s->pool_first = NULL;

    s->pool_cur = s->pool_end = NULL;

}

void tcg_context_init(TCGContext *s)

{

    int op, total_args, n;

    TCGOpDef *def;

    TCGArgConstraint *args_ct;

    int *sorted_args;

    memset(s, 0, sizeof(*s));

    s->temps = s->static_temps;

    s->nb_globals = 0;

    /* Count total number of arguments and allocate the corresponding

       space */

    total_args = 0;

    for(op = 0; op < NB_OPS; op++) {

        def = &tcg_op_defs[op];

        n = def->nb_iargs + def->nb_oargs;

        total_args += n;

    }

    args_ct = qemu_malloc(sizeof(TCGArgConstraint) * total_args);

    sorted_args = qemu_malloc(sizeof(int) * total_args);

    for(op = 0; op < NB_OPS; op++) {

        def = &tcg_op_defs[op];

        def->args_ct = args_ct;

        def->sorted_args = sorted_args;

        n = def->nb_iargs + def->nb_oargs;

        sorted_args += n;

        args_ct += n;

    }

    tcg_target_init(s);

    /* init global prologue and epilogue */

    s->code_buf = code_gen_prologue;

    s->code_ptr = s->code_buf;

    tcg_target_qemu_prologue(s);

    flush_icache_range((unsigned long)s->code_buf, 

                       (unsigned long)s->code_ptr);

}

void tcg_set_frame(TCGContext *s, int reg,

                   tcg_target_long start, tcg_target_long size)

{

    s->frame_start = start;

    s->frame_end = start + size;

    s->frame_reg = reg;

}

void tcg_set_macro_func(TCGContext *s, TCGMacroFunc *func)

{

    s->macro_func = func;

}

void tcg_func_start(TCGContext *s)

{

    tcg_pool_reset(s);

    s->nb_temps = s->nb_globals;

    s->labels = tcg_malloc(sizeof(TCGLabel) * TCG_MAX_LABELS);

    s->nb_labels = 0;

    s->current_frame_offset = s->frame_start;

    gen_opc_ptr = gen_opc_buf;

    gen_opparam_ptr = gen_opparam_buf;

}

static inline void tcg_temp_alloc(TCGContext *s, int n)

{

    if (n > TCG_MAX_TEMPS)

        tcg_abort();

}

TCGv tcg_global_reg_new(TCGType type, int reg, const char *name)

{

    TCGContext *s = &tcg_ctx;

    TCGTemp *ts;

    int idx;

#if TCG_TARGET_REG_BITS == 32

    if (type != TCG_TYPE_I32)

        tcg_abort();

#endif

    if (tcg_regset_test_reg(s->reserved_regs, reg))

        tcg_abort();

    idx = s->nb_globals;

    tcg_temp_alloc(s, s->nb_globals + 1);

    ts = &s->temps[s->nb_globals];

    ts->base_type = type;

    ts->type = type;

    ts->fixed_reg = 1;

    ts->reg = reg;

    ts->val_type = TEMP_VAL_REG;

    ts->name = name;

    s->nb_globals++;

    tcg_regset_set_reg(s->reserved_regs, reg);

    return MAKE_TCGV(idx);

}

TCGv tcg_global_mem_new(TCGType type, int reg, tcg_target_long offset,

                        const char *name)

{

    TCGContext *s = &tcg_ctx;

    TCGTemp *ts;

    int idx;

    idx = s->nb_globals;

#if TCG_TARGET_REG_BITS == 32

    if (type == TCG_TYPE_I64) {

        char buf[64];

        tcg_temp_alloc(s, s->nb_globals + 1);

        ts = &s->temps[s->nb_globals];

        ts->base_type = type;

        ts->type = TCG_TYPE_I32;

        ts->fixed_reg = 0;

        ts->mem_allocated = 1;

        ts->mem_reg = reg;

#ifdef TCG_TARGET_WORDS_BIGENDIAN

        ts->mem_offset = offset + 4;

#else

        ts->mem_offset = offset;

#endif

        ts->val_type = TEMP_VAL_MEM;

        pstrcpy(buf, sizeof(buf), name);

        pstrcat(buf, sizeof(buf), "_0");

        ts->name = strdup(buf);

        ts++;

        ts->base_type = type;

        ts->type = TCG_TYPE_I32;

        ts->fixed_reg = 0;

        ts->mem_allocated = 1;

        ts->mem_reg = reg;

#ifdef TCG_TARGET_WORDS_BIGENDIAN

        ts->mem_offset = offset;

#else

        ts->mem_offset = offset + 4;

#endif

        ts->val_type = TEMP_VAL_MEM;

        pstrcpy(buf, sizeof(buf), name);

        pstrcat(buf, sizeof(buf), "_1");

        ts->name = strdup(buf);

        s->nb_globals += 2;

    } else

#endif

    {

        tcg_temp_alloc(s, s->nb_globals + 1);

        ts = &s->temps[s->nb_globals];

        ts->base_type = type;

        ts->type = type;

        ts->fixed_reg = 0;

        ts->mem_allocated = 1;

        ts->mem_reg = reg;

        ts->mem_offset = offset;

        ts->val_type = TEMP_VAL_MEM;

        ts->name = name;

        s->nb_globals++;

    }

    return MAKE_TCGV(idx);

}

TCGv tcg_temp_new(TCGType type)

{

    TCGContext *s = &tcg_ctx;

    TCGTemp *ts;

    int idx;

    idx = s->nb_temps;

#if TCG_TARGET_REG_BITS == 32

    if (type == TCG_TYPE_I64) {

        tcg_temp_alloc(s, s->nb_temps + 1);

        ts = &s->temps[s->nb_temps];

        ts->base_type = type;

        ts->type = TCG_TYPE_I32;

        ts->fixed_reg = 0;

        ts->val_type = TEMP_VAL_DEAD;

        ts->mem_allocated = 0;

        ts->name = NULL;

        ts++;

        ts->base_type = TCG_TYPE_I32;

        ts->type = TCG_TYPE_I32;

        ts->val_type = TEMP_VAL_DEAD;

        ts->fixed_reg = 0;

        ts->mem_allocated = 0;

        ts->name = NULL;

        s->nb_temps += 2;

    } else

#endif

    {

        tcg_temp_alloc(s, s->nb_temps + 1);

        ts = &s->temps[s->nb_temps];

        ts->base_type = type;

        ts->type = type;

        ts->fixed_reg = 0;

        ts->val_type = TEMP_VAL_DEAD;

        ts->mem_allocated = 0;

        ts->name = NULL;

        s->nb_temps++;

    }

    return MAKE_TCGV(idx);

}

TCGv tcg_const_i32(int32_t val)

{

    TCGContext *s = &tcg_ctx;

    TCGTemp *ts;

    int idx;

    idx = s->nb_temps;

    tcg_temp_alloc(s, idx + 1);

    ts = &s->temps[idx];

    ts->base_type = ts->type = TCG_TYPE_I32;

    ts->val_type = TEMP_VAL_CONST;

    ts->name = NULL;

    ts->val = val;

    s->nb_temps++;

    return MAKE_TCGV(idx);

}

TCGv tcg_const_i64(int64_t val)

{

    TCGContext *s = &tcg_ctx;

    TCGTemp *ts;

    int idx;

    idx = s->nb_temps;

#if TCG_TARGET_REG_BITS == 32

    tcg_temp_alloc(s, idx + 2);

    ts = &s->temps[idx];

    ts->base_type = TCG_TYPE_I64;

    ts->type = TCG_TYPE_I32;

    ts->val_type = TEMP_VAL_CONST;

    ts->name = NULL;

    ts->val = val;

    ts++;

    ts->base_type = TCG_TYPE_I32;

    ts->type = TCG_TYPE_I32;

    ts->val_type = TEMP_VAL_CONST;

    ts->name = NULL;

    ts->val = val >> 32;

    s->nb_temps += 2;

#else

    tcg_temp_alloc(s, idx + 1);

    ts = &s->temps[idx];

    ts->base_type = ts->type = TCG_TYPE_I64;

    ts->val_type = TEMP_VAL_CONST;

    ts->name = NULL;

    ts->val = val;

    s->nb_temps++;

#endif    

    return MAKE_TCGV(idx);

}

void tcg_register_helper(void *func, const char *name)

{

    TCGContext *s = &tcg_ctx;

    int n;

    if ((s->nb_helpers + 1) > s->allocated_helpers) {

        n = s->allocated_helpers;

        if (n == 0) {

            n = 4;

        } else {

            n *= 2;

        }

        s->helpers = realloc(s->helpers, n * sizeof(TCGHelperInfo));

        s->allocated_helpers = n;

    }

    s->helpers[s->nb_helpers].func = func;

    s->helpers[s->nb_helpers].name = name;

    s->nb_helpers++;

}

const char *tcg_helper_get_name(TCGContext *s, void *func)

{

    int i;

    for(i = 0; i < s->nb_helpers; i++) {

        if (s->helpers[i].func == func)

            return s->helpers[i].name;

    }

    return NULL;

}

static inline TCGType tcg_get_base_type(TCGContext *s, TCGv arg)

{

    return s->temps[GET_TCGV(arg)].base_type;

}

static void tcg_gen_call_internal(TCGContext *s, TCGv func, 

                                  unsigned int flags,

                                  unsigned int nb_rets, const TCGv *rets,

                                  unsigned int nb_params, const TCGv *params)

{

    int i;

    *gen_opc_ptr++ = INDEX_op_call;

    *gen_opparam_ptr++ = (nb_rets << 16) | (nb_params + 1);

    for(i = 0; i < nb_rets; i++) {

        *gen_opparam_ptr++ = GET_TCGV(rets[i]);

    }

    for(i = 0; i < nb_params; i++) {

        *gen_opparam_ptr++ = GET_TCGV(params[i]);

    }

    *gen_opparam_ptr++ = GET_TCGV(func);

    *gen_opparam_ptr++ = flags;

    /* total parameters, needed to go backward in the instruction stream */

    *gen_opparam_ptr++ = 1 + nb_rets + nb_params + 3;

}

#if TCG_TARGET_REG_BITS < 64

/* Note: we convert the 64 bit args to 32 bit */

void tcg_gen_call(TCGContext *s, TCGv func, unsigned int flags,

                  unsigned int nb_rets, const TCGv *rets,

                  unsigned int nb_params, const TCGv *args1)

{

    TCGv ret, *args2, rets_2[2], arg;

    int j, i, call_type;

    if (nb_rets == 1) {

        ret = rets[0];

        if (tcg_get_base_type(s, ret) == TCG_TYPE_I64) {

            nb_rets = 2;

            rets_2[0] = ret;

            rets_2[1] = TCGV_HIGH(ret);

            rets = rets_2;

        }

    }

    args2 = alloca((nb_params * 2) * sizeof(TCGv));

    j = 0;

    call_type = (flags & TCG_CALL_TYPE_MASK);

    for(i = 0; i < nb_params; i++) {

        arg = args1[i];

        if (tcg_get_base_type(s, arg) == TCG_TYPE_I64) {

#ifdef TCG_TARGET_I386

            /* REGPARM case: if the third parameter is 64 bit, it is

               allocated on the stack */

            if (j == 2 && call_type == TCG_CALL_TYPE_REGPARM) {

                call_type = TCG_CALL_TYPE_REGPARM_2;

                flags = (flags & ~TCG_CALL_TYPE_MASK) | call_type;

            }

            args2[j++] = arg;

            args2[j++] = TCGV_HIGH(arg);

#else

#ifdef TCG_TARGET_WORDS_BIGENDIAN

            args2[j++] = TCGV_HIGH(arg);

            args2[j++] = arg;

#else

            args2[j++] = arg;

            args2[j++] = TCGV_HIGH(arg);

#endif

#endif

        } else {

            args2[j++] = arg;

        }

    }

    tcg_gen_call_internal(s, func, flags, 

                          nb_rets, rets, j, args2);

}

#else

void tcg_gen_call(TCGContext *s, TCGv func, unsigned int flags,

                  unsigned int nb_rets, const TCGv *rets,

                  unsigned int nb_params, const TCGv *args1)

{

    tcg_gen_call_internal(s, func, flags, 

                          nb_rets, rets, nb_params, args1);

}

#endif

#if TCG_TARGET_REG_BITS == 32

void tcg_gen_shifti_i64(TCGv ret, TCGv arg1, 

                        int c, int right, int arith)

{

    if (c == 0)

        return;

    if (c >= 32) {

        c -= 32;

        if (right) {

            if (arith) {

                tcg_gen_sari_i32(ret, TCGV_HIGH(arg1), c);

                tcg_gen_sari_i32(TCGV_HIGH(ret), TCGV_HIGH(arg1), 31);

            } else {

                tcg_gen_shri_i32(ret, TCGV_HIGH(arg1), c);

                tcg_gen_movi_i32(TCGV_HIGH(ret), 0);

            }

        } else {

            tcg_gen_shli_i32(TCGV_HIGH(ret), arg1, c);

            tcg_gen_movi_i32(ret, 0);

        }

    } else {

        TCGv t0, t1;

        t0 = tcg_temp_new(TCG_TYPE_I32);

        t1 = tcg_temp_new(TCG_TYPE_I32);

        if (right) {

            tcg_gen_shli_i32(t0, TCGV_HIGH(arg1), 32 - c);

            if (arith)

                tcg_gen_sari_i32(t1, TCGV_HIGH(arg1), c);

            else 

                tcg_gen_shri_i32(t1, TCGV_HIGH(arg1), c);

            tcg_gen_shri_i32(ret, arg1, c); 

            tcg_gen_or_i32(ret, ret, t0);

            tcg_gen_mov_i32(TCGV_HIGH(ret), t1);

        } else {

            tcg_gen_shri_i32(t0, arg1, 32 - c);

            /* Note: ret can be the same as arg1, so we use t1 */

            tcg_gen_shli_i32(t1, arg1, c); 

            tcg_gen_shli_i32(TCGV_HIGH(ret), TCGV_HIGH(arg1), c);

            tcg_gen_or_i32(TCGV_HIGH(ret), TCGV_HIGH(ret), t0);

            tcg_gen_mov_i32(ret, t1);

        }

    }

}

#endif

void tcg_reg_alloc_start(TCGContext *s)

{

    int i;

    TCGTemp *ts;

    for(i = 0; i < s->nb_globals; i++) {

        ts = &s->temps[i];

        if (ts->fixed_reg) {

            ts->val_type = TEMP_VAL_REG;

        } else {

            ts->val_type = TEMP_VAL_MEM;

        }

    }

    for(i = 0; i < TCG_TARGET_NB_REGS; i++) {

        s->reg_to_temp[i] = -1;

    }

}

static char *tcg_get_arg_str_idx(TCGContext *s, char *buf, int buf_size,

                                 int idx)

{

    TCGTemp *ts;

    ts = &s->temps[idx];

    if (idx < s->nb_globals) {

        pstrcpy(buf, buf_size, ts->name);

    } else {

        if (ts->val_type == TEMP_VAL_CONST) {

            snprintf(buf, buf_size, "$0x%" TCG_PRIlx , ts->val);

        } else {

            snprintf(buf, buf_size, "tmp%d", idx - s->nb_globals);

        }

    }

    return buf;

}

char *tcg_get_arg_str(TCGContext *s, char *buf, int buf_size, TCGv arg)

{

    return tcg_get_arg_str_idx(s, buf, buf_size, GET_TCGV(arg));

}

void tcg_dump_ops(TCGContext *s, FILE *outfile)

{

    const uint16_t *opc_ptr;

    const TCGArg *args;

    TCGArg arg;

    int c, i, k, nb_oargs, nb_iargs, nb_cargs;

    const TCGOpDef *def;

    char buf[128];

    opc_ptr = gen_opc_buf;

    args = gen_opparam_buf;

    while (opc_ptr < gen_opc_ptr) {

        c = *opc_ptr++;

        def = &tcg_op_defs[c];

        fprintf(outfile, " %s ", def->name);

        if (c == INDEX_op_call) {

            TCGArg arg;

            /* variable number of arguments */

            arg = *args++;

            nb_oargs = arg >> 16;

            nb_iargs = arg & 0xffff;

            nb_cargs = def->nb_cargs;

            /* function name */

            /* XXX: dump helper name for call */

            fprintf(outfile, "%s",

                    tcg_get_arg_str_idx(s, buf, sizeof(buf), args[nb_oargs + nb_iargs - 1]));

            /* flags */

            fprintf(outfile, ",$0x%" TCG_PRIlx,

                    args[nb_oargs + nb_iargs]);

            /* nb out args */

            fprintf(outfile, ",$%d", nb_oargs);

            for(i = 0; i < nb_oargs; i++) {

                fprintf(outfile, ",");

                fprintf(outfile, "%s",

                        tcg_get_arg_str_idx(s, buf, sizeof(buf), args[i]));

            }

            for(i = 0; i < (nb_iargs - 1); i++) {

                fprintf(outfile, ",");

                fprintf(outfile, "%s",

                        tcg_get_arg_str_idx(s, buf, sizeof(buf), args[nb_oargs + i]));

            }

        } else {

            if (c == INDEX_op_nopn) {

                /* variable number of arguments */

                nb_cargs = *args;

                nb_oargs = 0;

                nb_iargs = 0;

            } else {

                nb_oargs = def->nb_oargs;

                nb_iargs = def->nb_iargs;

                nb_cargs = def->nb_cargs;

            }

            k = 0;

            for(i = 0; i < nb_oargs; i++) {

                if (k != 0)

                    fprintf(outfile, ",");

                fprintf(outfile, "%s",

                        tcg_get_arg_str_idx(s, buf, sizeof(buf), args[k++]));

            }

            for(i = 0; i < nb_iargs; i++) {

                if (k != 0)

                    fprintf(outfile, ",");

                fprintf(outfile, "%s",

                        tcg_get_arg_str_idx(s, buf, sizeof(buf), args[k++]));

            }

            for(i = 0; i < nb_cargs; i++) {

                if (k != 0)

                    fprintf(outfile, ",");

                arg = args[k++];

                fprintf(outfile, "$0x%" TCG_PRIlx, arg);

            }

        }

        fprintf(outfile, "\n");

        args += nb_iargs + nb_oargs + nb_cargs;

    }

}

/* we give more priority to constraints with less registers */

static int get_constraint_priority(const TCGOpDef *def, int k)

{

    const TCGArgConstraint *arg_ct;

    int i, n;

    arg_ct = &def->args_ct[k];

    if (arg_ct->ct & TCG_CT_ALIAS) {

        /* an alias is equivalent to a single register */

        n = 1;

    } else {

        if (!(arg_ct->ct & TCG_CT_REG))

            return 0;

        n = 0;

        for(i = 0; i < TCG_TARGET_NB_REGS; i++) {

            if (tcg_regset_test_reg(arg_ct->u.regs, i))

                n++;

        }

    }

    return TCG_TARGET_NB_REGS - n + 1;

}

/* sort from highest priority to lowest */

static void sort_constraints(TCGOpDef *def, int start, int n)

{

    int i, j, p1, p2, tmp;

    for(i = 0; i < n; i++)

        def->sorted_args[start + i] = start + i;

    if (n <= 1)

        return;

    for(i = 0; i < n - 1; i++) {

        for(j = i + 1; j < n; j++) {

            p1 = get_constraint_priority(def, def->sorted_args[start + i]);

            p2 = get_constraint_priority(def, def->sorted_args[start + j]);

            if (p1 < p2) {

                tmp = def->sorted_args[start + i];

                def->sorted_args[start + i] = def->sorted_args[start + j];

                def->sorted_args[start + j] = tmp;

            }

        }

    }

}

void tcg_add_target_add_op_defs(const TCGTargetOpDef *tdefs)

{

    int op;

    TCGOpDef *def;

    const char *ct_str;

    int i, nb_args;

    for(;;) {

        if (tdefs->op < 0)

            break;

        op = tdefs->op;

        assert(op >= 0 && op < NB_OPS);

        def = &tcg_op_defs[op];

        nb_args = def->nb_iargs + def->nb_oargs;

        for(i = 0; i < nb_args; i++) {

            ct_str = tdefs->args_ct_str[i];

            tcg_regset_clear(def->args_ct[i].u.regs);

            def->args_ct[i].ct = 0;

            if (ct_str[0] >= '0' && ct_str[0] <= '9') {

                int oarg;

                oarg = ct_str[0] - '0';

                assert(oarg < def->nb_oargs);

                assert(def->args_ct[oarg].ct & TCG_CT_REG);

                /* TCG_CT_ALIAS is for the output arguments. The input

                   argument is tagged with TCG_CT_IALIAS. */

                def->args_ct[i] = def->args_ct[oarg];

                def->args_ct[oarg].ct = TCG_CT_ALIAS;

                def->args_ct[oarg].alias_index = i;

                def->args_ct[i].ct |= TCG_CT_IALIAS;

                def->args_ct[i].alias_index = oarg;

            } else {

                for(;;) {

                    if (*ct_str == '\0')

                        break;

                    switch(*ct_str) {

                    case 'i':

                        def->args_ct[i].ct |= TCG_CT_CONST;

                        ct_str++;

                        break;

                    default:

                        if (target_parse_constraint(&def->args_ct[i], &ct_str) < 0) {

                            fprintf(stderr, "Invalid constraint '%s' for arg %d of operation '%s'\n",

                                    ct_str, i, def->name);

                            exit(1);

                        }

                    }

                }

            }

        }

        /* sort the constraints (XXX: this is just an heuristic) */

        sort_constraints(def, 0, def->nb_oargs);

        sort_constraints(def, def->nb_oargs, def->nb_iargs);

#if 0

        {

            int i;

            printf("%s: sorted=", def->name);

            for(i = 0; i < def->nb_oargs + def->nb_iargs; i++)

                printf(" %d", def->sorted_args[i]);

            printf("\n");

        }

#endif

        tdefs++;

    }

}

#ifdef USE_LIVENESS_ANALYSIS

/* set a nop for an operation using 'nb_args' */

static inline void tcg_set_nop(TCGContext *s, uint16_t *opc_ptr, 

                               TCGArg *args, int nb_args)

{

    if (nb_args == 0) {

        *opc_ptr = INDEX_op_nop;

    } else {

        *opc_ptr = INDEX_op_nopn;

        args[0] = nb_args;

        args[nb_args - 1] = nb_args;

    }

}

/* liveness analysis: end of basic block: globals are live, temps are dead */

static inline void tcg_la_bb_end(TCGContext *s, uint8_t *dead_temps)

{

    memset(dead_temps, 0, s->nb_globals);

    memset(dead_temps + s->nb_globals, 1, s->nb_temps - s->nb_globals);

}

/* Liveness analysis : update the opc_dead_iargs array to tell if a

   given input arguments is dead. Instructions updating dead

   temporaries are removed. */

void tcg_liveness_analysis(TCGContext *s)

{

    int i, op_index, op, nb_args, nb_iargs, nb_oargs, arg, nb_ops;

    TCGArg *args;

    const TCGOpDef *def;

    uint8_t *dead_temps;

    unsigned int dead_iargs;

    gen_opc_ptr++; /* skip end */

    nb_ops = gen_opc_ptr - gen_opc_buf;

    /* XXX: make it really dynamic */

    s->op_dead_iargs = tcg_malloc(OPC_BUF_SIZE * sizeof(uint16_t));

    dead_temps = tcg_malloc(s->nb_temps);

    memset(dead_temps, 1, s->nb_temps);

    args = gen_opparam_ptr;

    op_index = nb_ops - 1;

    while (op_index >= 0) {

        op = gen_opc_buf[op_index];

        def = &tcg_op_defs[op];

        switch(op) {

        case INDEX_op_call: