i386-gen.c

   1 /*
   2  *  X86 code generator for TCC
   3  *
   4  *  Copyright (c) 2001 Fabrice Bellard
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 /* number of available registers */
  22 #define NB_REGS             4
  23
  24 /* a register can belong to several classes */
  25 #define RC_INT     0x0001 /* generic integer register */
  26 #define RC_FLOAT   0x0002 /* generic float register */
  27 #define RC_EAX     0x0004
  28 #define RC_FRET    0x0008 /* function return: float register */
  29 #define RC_ECX     0x0010
  30 #define RC_EDX     0x0020
  31 #define RC_IRET    RC_EAX /* function return: integer register */
  32 #define RC_LRET    RC_EDX /* function return: second integer register */
  33
  34 /* pretty names for the registers */
  35 enum {
  36     REG_EAX = 0,
  37     REG_ECX,
  38     REG_EDX,
  39     REG_ST0,
  40 };
  41
  42 int reg_classes[NB_REGS] = {
  43     /* eax */ RC_INT | RC_IRET,
  44     /* ecx */ RC_INT | RC_ECX,
  45     /* edx */ RC_INT | RC_EDX,
  46     /* st0 */ RC_FLOAT | RC_FRET,
  47 };
  48
  49 /* return registers for function */
  50 #define REG_IRET REG_EAX /* single word int return register */
  51 #define REG_LRET REG_EDX /* second word return register (for long long) */
  52 #define REG_FRET REG_ST0 /* float return register */
  53
  54 /* defined if function parameters must be evaluated in reverse order */
  55 #define INVERT_FUNC_PARAMS
  56
  57 /* defined if structures are passed as pointers. Otherwise structures
  58    are directly pushed on stack. */
  59 //#define FUNC_STRUCT_PARAM_AS_PTR
  60
  61 /* pointer size, in bytes */
  62 #define PTR_SIZE 4
  63
  64 /* long double size and alignment, in bytes */
  65 #define LDOUBLE_SIZE  12
  66 #define LDOUBLE_ALIGN 4
  67
  68 /* function call context */
  69 typedef struct GFuncContext {
  70     int args_size;
  71 } GFuncContext;
  72
  73 /******************************************************/
  74
  75 static int *func_sub_sp_ptr;
  76
  77 void g(int c)
  78 {
  79     *(char *)ind++ = c;
  80 }
  81
  82 void o(int c)
  83 {
  84     while (c) {
  85         g(c);
  86         c = c / 256;
  87     }
  88 }
  89
  90 void gen_le32(int c)
  91 {
  92     g(c);
  93     g(c >> 8);
  94     g(c >> 16);
  95     g(c >> 24);
  96 }
  97
  98 /* patch relocation entry with value 'val' */
  99 void greloc_patch1(Reloc *p, int val)
 100 {
 101     switch(p->type) {
 102     case RELOC_ADDR32:
 103         *(int *)p->addr = val;
 104         break;
 105     case RELOC_REL32:
 106         *(int *)p->addr = val - p->addr - 4;
 107         break;
 108     }
 109 }
 110
 111 /* output a symbol and patch all calls to it */
 112 void gsym_addr(t, a)
 113 {
 114     int n;
 115     while (t) {
 116         n = *(int *)t; /* next value */
 117         *(int *)t = a - t - 4;
 118         t = n;
 119     }
 120 }
 121
 122 void gsym(t)
 123 {
 124     gsym_addr(t, ind);
 125 }
 126
 127 /* psym is used to put an instruction with a data field which is a
 128    reference to a symbol. It is in fact the same as oad ! */
 129 #define psym oad
 130
 131 /* instruction + 4 bytes data. Return the address of the data */
 132 int oad(int c, int s)
 133 {
 134     o(c);
 135     *(int *)ind = s;
 136     s = ind;
 137     ind = ind + 4;
 138     return s;
 139 }
 140
 141 /* output constant with relocation if 'r & VT_FORWARD' is true */
 142 void gen_addr32(int r, int c)
 143 {
 144     if (!(r & VT_FORWARD)) {
 145         gen_le32(c);
 146     } else {
 147         greloc((Sym *)c, ind, RELOC_ADDR32);
 148         gen_le32(0);
 149     }
 150 }
 151
 152 /* generate a modrm reference. 'op_reg' contains the addtionnal 3
 153    opcode bits */
 154 void gen_modrm(int op_reg, int r, int c)
 155 {
 156     op_reg = op_reg << 3;
 157     if ((r & VT_VALMASK) == VT_CONST) {
 158         /* constant memory reference */
 159         o(0x05 | op_reg);
 160         gen_addr32(r, c);
 161     } else if ((r & VT_VALMASK) == VT_LOCAL) {
 162         /* currently, we use only ebp as base */
 163         if (c == (char)c) {
 164             /* short reference */
 165             o(0x45 | op_reg);
 166             g(c);
 167         } else {
 168             oad(0x85 | op_reg, c);
 169         }
 170     } else {
 171         g(0x00 | op_reg | (r & VT_VALMASK));
 172     }
 173 }
 174
 175
 176 /* load 'r' from value 'sv' */
 177 void load(int r, SValue *sv)
 178 {
 179     int v, t, ft, fc, fr;
 180     SValue v1;
 181
 182     fr = sv->r;
 183     ft = sv->t;
 184     fc = sv->c.ul;
 185
 186     v = fr & VT_VALMASK;
 187     if (fr & VT_LVAL) {
 188         if (v == VT_LLOCAL) {
 189             v1.t = VT_INT;
 190             v1.r = VT_LOCAL | VT_LVAL;
 191             v1.c.ul = fc;
 192             load(r, &v1);
 193             fr = r;
 194         }
 195         if ((ft & VT_BTYPE) == VT_FLOAT) {
 196             o(0xd9); /* flds */
 197             r = 0;
 198         } else if ((ft & VT_BTYPE) == VT_DOUBLE) {
 199             o(0xdd); /* fldl */
 200             r = 0;
 201         } else if ((ft & VT_BTYPE) == VT_LDOUBLE) {
 202             o(0xdb); /* fldt */
 203             r = 5;
 204         } else if ((ft & VT_TYPE) == VT_BYTE)
 205             o(0xbe0f);   /* movsbl */
 206         else if ((ft & VT_TYPE) == (VT_BYTE | VT_UNSIGNED))
 207             o(0xb60f);   /* movzbl */
 208         else if ((ft & VT_TYPE) == VT_SHORT)
 209             o(0xbf0f);   /* movswl */
 210         else if ((ft & VT_TYPE) == (VT_SHORT | VT_UNSIGNED))
 211             o(0xb70f);   /* movzwl */
 212         else
 213             o(0x8b);     /* movl */
 214         gen_modrm(r, fr, fc);
 215     } else {
 216         if (v == VT_CONST) {
 217             o(0xb8 + r); /* mov $xx, r */
 218             gen_addr32(fr, fc);
 219         } else if (v == VT_LOCAL) {
 220             o(0x8d); /* lea xxx(%ebp), r */
 221             gen_modrm(r, VT_LOCAL, fc);
 222         } else if (v == VT_CMP) {
 223             oad(0xb8 + r, 0); /* mov $0, r */
 224             o(0x0f); /* setxx %br */
 225             o(fc);
 226             o(0xc0 + r);
 227         } else if (v == VT_JMP || v == VT_JMPI) {
 228             t = v & 1;
 229             oad(0xb8 + r, t); /* mov $1, r */
 230             oad(0xe9, 5); /* jmp after */
 231             gsym(fc);
 232             oad(0xb8 + r, t ^ 1); /* mov $0, r */
 233         } else if (v != r) {
 234             o(0x89);
 235             o(0xc0 + r + v * 8); /* mov v, r */
 236         }
 237     }
 238 }
 239
 240 /* store register 'r' in lvalue 'v' */
 241 void store(int r, SValue *v)
 242 {
 243     int fr, bt, ft, fc;
 244
 245     ft = v->t;
 246     fc = v->c.ul;
 247     fr = v->r & VT_VALMASK;
 248     bt = ft & VT_BTYPE;
 249     /* XXX: incorrect if float reg to reg */
 250     if (bt == VT_FLOAT) {
 251         o(0xd9); /* fsts */
 252         r = 2;
 253     } else if (bt == VT_DOUBLE) {
 254         o(0xdd); /* fstpl */
 255         r = 2;
 256     } else if (bt == VT_LDOUBLE) {
 257         o(0xc0d9); /* fld %st(0) */
 258         o(0xdb); /* fstpt */
 259         r = 7;
 260     } else {
 261         if (bt == VT_SHORT)
 262             o(0x66);
 263         if (bt == VT_BYTE)
 264             o(0x88);
 265         else
 266             o(0x89);
 267     }
 268     if (fr == VT_CONST ||
 269         fr == VT_LOCAL ||
 270         (v->r & VT_LVAL)) {
 271         gen_modrm(r, v->r, fc);
 272     } else if (fr != r) {
 273         o(0xc0 + fr + r * 8); /* mov r, fr */
 274     }
 275 }
 276
 277 /* start function call and return function call context */
 278 void gfunc_start(GFuncContext *c)
 279 {
 280     c->args_size = 0;
 281 }
 282
 283 /* push function parameter which is in (vtop->t, vtop->c). Stack entry
 284    is then popped. */
 285 void gfunc_param(GFuncContext *c)
 286 {
 287     int size, align, r;
 288
 289     if ((vtop->t & VT_BTYPE) == VT_STRUCT) {
 290         size = type_size(vtop->t, &align);
 291         /* align to stack align size */
 292         size = (size + 3) & ~3;
 293         /* allocate the necessary size on stack */
 294         oad(0xec81, size); /* sub $xxx, %esp */
 295         /* generate structure store */
 296         r = get_reg(RC_INT);
 297         o(0x89); /* mov %esp, r */
 298         o(0xe0 + r);
 299         vset(VT_INT, r, 0);
 300         vswap();
 301         vstore();
 302         c->args_size += size;
 303     } else if (is_float(vtop->t)) {
 304         gv(RC_FLOAT); /* only one float register */
 305         if ((vtop->t & VT_BTYPE) == VT_FLOAT)
 306             size = 4;
 307         else if ((vtop->t & VT_BTYPE) == VT_DOUBLE)
 308             size = 8;
 309         else
 310             size = 12;
 311         oad(0xec81, size); /* sub $xxx, %esp */
 312         if (size == 12)
 313             o(0x7cdb);
 314         else
 315             o(0x5cd9 + size - 4); /* fstp[s|l] 0(%esp) */
 316         g(0x24);
 317         g(0x00);
 318         c->args_size += size;
 319     } else {
 320         /* simple type (currently always same size) */
 321         /* XXX: implicit cast ? */
 322         r = gv(RC_INT);
 323         if ((vtop->t & VT_BTYPE) == VT_LLONG) {
 324             size = 8;
 325             o(0x50 + vtop->r2); /* push r */
 326         } else {
 327             size = 4;
 328         }
 329         o(0x50 + r); /* push r */
 330         c->args_size += size;
 331     }
 332     vtop--;
 333 }
 334
 335 /* generate function call with address in (vtop->t, vtop->c) and free function
 336    context. Stack entry is popped */
 337 void gfunc_call(GFuncContext *c)
 338 {
 339     int r;
 340     if ((vtop->r & (VT_VALMASK | VT_LVAL)) == VT_CONST) {
 341         /* constant case */
 342         /* forward reference */
 343         if (vtop->r & VT_FORWARD) {
 344             greloc(vtop->c.sym, ind + 1, RELOC_REL32);
 345             oad(0xe8, 0);
 346         } else {
 347             oad(0xe8, vtop->c.ul - ind - 5);
 348         }
 349     } else {
 350         /* otherwise, indirect call */
 351         r = gv(RC_INT);
 352         o(0xff); /* call *r */
 353         o(0xd0 + r);
 354     }
 355     if (c->args_size)
 356         oad(0xc481, c->args_size); /* add $xxx, %esp */
 357     vtop--;
 358 }
 359
 360 /* generate function prolog of type 't' */
 361 void gfunc_prolog(int t)
 362 {
 363     int addr, align, size, u;
 364     Sym *sym;
 365
 366     sym = sym_find((unsigned)t >> VT_STRUCT_SHIFT);
 367     addr = 8;
 368     /* if the function returns a structure, then add an
 369        implicit pointer parameter */
 370     func_vt = sym->t;
 371     if ((func_vt & VT_BTYPE) == VT_STRUCT) {
 372         func_vc = addr;
 373         addr += 4;
 374     }
 375     /* define parameters */
 376     while ((sym = sym->next) != NULL) {
 377         u = sym->t;
 378         sym_push(sym->v & ~SYM_FIELD, u,
 379                  VT_LOCAL | VT_LVAL, addr);
 380         size = type_size(u, &align);
 381         size = (size + 3) & ~3;
 382 #ifdef FUNC_STRUCT_PARAM_AS_PTR
 383         /* structs are passed as pointer */
 384         if ((u & VT_BTYPE) == VT_STRUCT) {
 385             size = 4;
 386         }
 387 #endif
 388         addr += size;
 389     }
 390     o(0xe58955); /* push   %ebp, mov    %esp, %ebp */
 391     func_sub_sp_ptr = (int *)oad(0xec81, 0); /* sub $xxx, %esp */
 392 }
 393
 394 /* generate function epilog */
 395 void gfunc_epilog(void)
 396 {
 397     o(0xc3c9); /* leave, ret */
 398     *func_sub_sp_ptr = (-loc + 3) & -4; /* align local size to word &
 399                                            save local variables */
 400 }
 401
 402 int gjmp(int t)
 403 {
 404     return psym(0xe9, t);
 405 }
 406
 407 /* generate a test. set 'inv' to invert test. Stack entry is popped */
 408 int gtst(int inv, int t)
 409 {
 410     int v, *p;
 411     v = vtop->r & VT_VALMASK;
 412     if (v == VT_CMP) {
 413         /* fast case : can jump directly since flags are set */
 414         g(0x0f);
 415         t = psym((vtop->c.i - 16) ^ inv, t);
 416     } else if (v == VT_JMP || v == VT_JMPI) {
 417         /* && or || optimization */
 418         if ((v & 1) == inv) {
 419             /* insert vtop->c jump list in t */
 420             p = &vtop->c.i;
 421             while (*p != 0)
 422                 p = (int *)*p;
 423             *p = t;
 424             t = vtop->c.i;
 425         } else {
 426             t = gjmp(t);
 427             gsym(vtop->c.i);
 428         }
 429     } else {
 430         if (is_float(vtop->t)) {
 431             vpushi(0);
 432             gen_op(TOK_NE);
 433         }
 434         if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_FORWARD)) == VT_CONST) {
 435             /* constant jmp optimization */
 436             if ((vtop->c.i != 0) != inv)
 437                 t = gjmp(t);
 438         } else {
 439             v = gv(RC_INT);
 440             o(0x85);
 441             o(0xc0 + v * 9);
 442             g(0x0f);
 443             t = psym(0x85 ^ inv, t);
 444         }
 445     }
 446     vtop--;
 447     return t;
 448 }
 449
 450 /* generate an integer binary operation */
 451 void gen_opi(int op)
 452 {
 453     int r, fr, opc, c;
 454
 455     switch(op) {
 456     case '+':
 457     case TOK_ADDC1: /* add with carry generation */
 458         opc = 0;
 459     gen_op8:
 460         vswap();
 461         r = gv(RC_INT);
 462         vswap();
 463         if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_FORWARD)) == VT_CONST) {
 464             /* constant case */
 465             c = vtop->c.i;
 466             if (c == (char)c) {
 467                 /* XXX: generate inc and dec for smaller code ? */
 468                 o(0x83);
 469                 o(0xc0 | (opc << 3) | r);
 470                 g(c);
 471             } else {
 472                 o(0x81);
 473                 oad(0xc0 | (opc << 3) | r, c);
 474             }
 475         } else {
 476             fr = gv(RC_INT);
 477             o((opc << 3) | 0x01);
 478             o(0xc0 + r + fr * 8);
 479         }
 480         vtop--;
 481         if (op >= TOK_ULT && op <= TOK_GT) {
 482             vtop--;
 483             vset(VT_INT, VT_CMP, op);
 484         }
 485         break;
 486     case '-':
 487     case TOK_SUBC1: /* sub with carry generation */
 488         opc = 5;
 489         goto gen_op8;
 490     case TOK_ADDC2: /* add with carry use */
 491         opc = 2;
 492         goto gen_op8;
 493     case TOK_SUBC2: /* sub with carry use */
 494         opc = 3;
 495         goto gen_op8;
 496     case '&':
 497         opc = 4;
 498         goto gen_op8;
 499     case '^':
 500         opc = 6;
 501         goto gen_op8;
 502     case '|':
 503         opc = 1;
 504         goto gen_op8;
 505     case '*':
 506         vswap();
 507         r = gv(RC_INT);
 508         vswap();
 509         fr = gv(RC_INT);
 510         vtop--;
 511         o(0xaf0f); /* imul fr, r */
 512         o(0xc0 + fr + r * 8);
 513         break;
 514     case TOK_SHL:
 515         opc = 4;
 516         goto gen_shift;
 517     case TOK_SHR:
 518         opc = 5;
 519         goto gen_shift;
 520     case TOK_SAR:
 521         opc = 7;
 522     gen_shift:
 523         vswap();
 524         r = gv(RC_INT);
 525         vswap();
 526         opc = 0xc0 | (opc << 3);
 527         if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_FORWARD)) == VT_CONST) {
 528             /* constant case */
 529             c = vtop->c.i & 0x1f;
 530             o(0xc1); /* shl/shr/sar $xxx, r */
 531             o(opc | r);
 532             g(c);
 533         } else {
 534             /* we generate the shift in ecx */
 535             gv(RC_ECX);
 536             /* the first op may have been spilled, so we reload it if
 537                needed */
 538             vswap();
 539             r = gv(RC_INT);
 540             vswap();
 541             o(0xd3); /* shl/shr/sar %cl, r */
 542             o(opc | r);
 543         }
 544         vtop--;
 545         vtop->r = r;
 546         break;
 547     case '/':
 548     case TOK_UDIV:
 549     case TOK_PDIV:
 550     case '%':
 551     case TOK_UMOD:
 552     case TOK_UMULL:
 553         vswap();
 554         r = gv(RC_EAX); /* first operand must be in eax */
 555         vswap();
 556         /* XXX: need better constraint */
 557         fr = gv(RC_ECX); /* second operand in ecx */
 558         vswap();
 559         r = gv(RC_EAX); /* reload first operand if flushed */
 560         vswap();
 561         vtop--;
 562         save_reg(REG_EDX);
 563         if (op == TOK_UMULL) {
 564             o(0xf7); /* mul fr */
 565             o(0xe0 + fr);
 566             vtop->r2 = REG_EDX;
 567             r = REG_EAX;
 568         } else {
 569             if (op == TOK_UDIV || op == TOK_UMOD) {
 570                 o(0xf7d231); /* xor %edx, %edx, div fr, %eax */
 571                 o(0xf0 + fr);
 572             } else {
 573                 o(0xf799); /* cltd, idiv fr, %eax */
 574                 o(0xf8 + fr);
 575             }
 576             if (op == '%' || op == TOK_UMOD)
 577                 r = REG_EDX;
 578             else
 579                 r = REG_EAX;
 580         }
 581         vtop->r = r;
 582         break;
 583     default:
 584         opc = 7;
 585         goto gen_op8;
 586     }
 587 }
 588
 589 /* generate a floating point operation 'v = t1 op t2' instruction. The
 590    two operands are guaranted to have the same floating point type */
 591 /* NOTE: currently floats can only be lvalues */
 592 void gen_opf(int op)
 593 {
 594     int a, ft, fc, swapped;
 595
 596     /* convert constants to memory references */
 597     if ((vtop[-1].r & (VT_VALMASK | VT_LVAL)) == VT_CONST) {
 598         vswap();
 599         gv(RC_FLOAT);
 600         vswap();
 601     }
 602     if ((vtop[0].r & (VT_VALMASK | VT_LVAL)) == VT_CONST)
 603         gv(RC_FLOAT);
 604
 605     /* must put at least one value in the floating point register */
 606     if ((vtop[-1].r & VT_LVAL) &&
 607         (vtop[0].r & VT_LVAL)) {
 608         vswap();
 609         gv(RC_FLOAT);
 610         vswap();
 611     }
 612     if (op >= TOK_ULT && op <= TOK_GT) {
 613         /* load on stack second operand */
 614         load(REG_ST0, vtop);
 615         if (op == TOK_GE || op == TOK_GT)
 616             o(0xc9d9); /* fxch %st(1) */
 617         o(0xe9da); /* fucompp */
 618         o(0xe0df); /* fnstsw %ax */
 619         if (op == TOK_EQ) {
 620             o(0x45e480); /* and $0x45, %ah */
 621             o(0x40fC80); /* cmp $0x40, %ah */
 622         } else if (op == TOK_NE) {
 623             o(0x45e480); /* and $0x45, %ah */
 624             o(0x40f480); /* xor $0x40, %ah */
 625             op = TOK_NE;
 626         } else if (op == TOK_GE || op == TOK_LE) {
 627             o(0x05c4f6); /* test $0x05, %ah */
 628             op = TOK_EQ;
 629         } else {
 630             o(0x45c4f6); /* test $0x45, %ah */
 631             op = TOK_EQ;
 632         }
 633         vtop--;
 634         vtop->r = VT_CMP;
 635         vtop->c.i = op;
 636     } else {
 637         swapped = 0;
 638         /* swap the stack if needed so that t1 is the register and t2 is
 639            the memory reference */
 640         if (vtop[-1].r & VT_LVAL) {
 641             vswap();
 642             swapped = 1;
 643         }
 644         /* no memory reference possible for long double operations */
 645         if ((vtop->t & VT_BTYPE) == VT_LDOUBLE) {
 646             load(REG_ST0, vtop);
 647             swapped = !swapped;
 648         }
 649
 650         switch(op) {
 651         default:
 652         case '+':
 653             a = 0;
 654             break;
 655         case '-':
 656             a = 4;
 657             if (swapped)
 658                 a++;
 659             break;
 660         case '*':
 661             a = 1;
 662             break;
 663         case '/':
 664             a = 6;
 665             if (swapped)
 666                 a++;
 667             break;
 668         }
 669         ft = vtop->t;
 670         fc = vtop->c.ul;
 671         if ((ft & VT_BTYPE) == VT_LDOUBLE) {
 672             o(0xde); /* fxxxp %st, %st(1) */
 673             o(0xc1 + (a << 3));
 674         } else {
 675             if ((ft & VT_BTYPE) == VT_DOUBLE)
 676                 o(0xdc);
 677             else
 678                 o(0xd8);
 679             gen_modrm(a, vtop->r, fc);
 680         }
 681         vtop--;
 682     }
 683 }
 684
 685 /* FPU control word for rounding to nearest mode */
 686 /* XXX: should move that into tcc lib support code ! */
 687 static unsigned short __tcc_fpu_control = 0x137f;
 688 /* FPU control word for round to zero mode for int convertion */
 689 static unsigned short __tcc_int_fpu_control = 0x137f | 0x0c00;
 690
 691 /* convert integers to fp 't' type. Must handle 'int', 'unsigned int'
 692    and 'long long' cases. */
 693 void gen_cvt_itof(int t)
 694 {
 695     gv(RC_INT);
 696     if ((vtop->t & VT_BTYPE) == VT_LLONG) {
 697         /* signed long long to float/double/long double (unsigned case
 698            is handled generically) */
 699         o(0x50 + vtop->r2); /* push r2 */
 700         o(0x50 + (vtop->r & VT_VALMASK)); /* push r */
 701         o(0x242cdf); /* fildll (%esp) */
 702         o(0x08c483); /* add $8, %esp */
 703     } else if ((vtop->t & (VT_BTYPE | VT_UNSIGNED)) ==
 704                (VT_INT | VT_UNSIGNED)) {
 705         /* unsigned int to float/double/long double */
 706         o(0x6a); /* push $0 */
 707         g(0x00);
 708         o(0x50 + (vtop->r & VT_VALMASK)); /* push r */
 709         o(0x242cdf); /* fildll (%esp) */
 710         o(0x08c483); /* add $8, %esp */
 711     } else {
 712         /* int to float/double/long double */
 713         o(0x50 + (vtop->r & VT_VALMASK)); /* push r */
 714         o(0x2404db); /* fildl (%esp) */
 715         o(0x04c483); /* add $4, %esp */
 716     }
 717     vtop->r = REG_ST0;
 718 }
 719
 720 /* convert fp to int 't' type */
 721 /* XXX: handle long long case */
 722 void gen_cvt_ftoi(int t)
 723 {
 724     int r, r2, size;
 725
 726     gv(RC_FLOAT);
 727     if (t != VT_INT)
 728         size = 8;
 729     else
 730         size = 4;
 731
 732     oad(0x2dd9, (int)&__tcc_int_fpu_control); /* ldcw xxx */
 733     oad(0xec81, size); /* sub $xxx, %esp */
 734     if (size == 4)
 735         o(0x1cdb); /* fistpl */
 736     else
 737         o(0x3cdf); /* fistpll */
 738     o(0x24);
 739     oad(0x2dd9, (int)&__tcc_fpu_control); /* ldcw xxx */
 740     r = get_reg(RC_INT);
 741     o(0x58 + r); /* pop r */
 742     if (size == 8) {
 743         if (t == VT_LLONG) {
 744             vtop->r = r; /* mark reg as used */
 745             r2 = get_reg(RC_INT);
 746             o(0x58 + r2); /* pop r2 */
 747             vtop->r2 = r2;
 748         } else {
 749             o(0x04c483); /* add $4, %esp */
 750         }
 751     }
 752     vtop->r = r;
 753 }
 754
 755 /* convert from one floating point type to another */
 756 void gen_cvt_ftof(int t)
 757 {
 758     /* all we have to do on i386 is to put the float in a register */
 759     gv(RC_FLOAT);
 760 }
 761
 762 /* end of X86 code generator */
 763 /*************************************************************/
 764