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. The classes must be
  25    sorted from more general to more precise (see gv2() code which does
  26    assumptions on it). */
  27 #define RC_INT     0x0001 /* generic integer register */
  28 #define RC_FLOAT   0x0002 /* generic float register */
  29 #define RC_EAX     0x0004
  30 #define RC_ST0     0x0008
  31 #define RC_ECX     0x0010
  32 #define RC_EDX     0x0020
  33 #define RC_IRET    RC_EAX /* function return: integer register */
  34 #define RC_LRET    RC_EDX /* function return: second integer register */
  35 #define RC_FRET    RC_ST0 /* function return: float register */
  36
  37 /* pretty names for the registers */
  38 enum {
  39     REG_EAX = 0,
  40     REG_ECX,
  41     REG_EDX,
  42     REG_ST0,
  43 };
  44
  45 int reg_classes[NB_REGS] = {
  46     /* eax */ RC_INT | RC_EAX,
  47     /* ecx */ RC_INT | RC_ECX,
  48     /* edx */ RC_INT | RC_EDX,
  49     /* st0 */ RC_FLOAT | RC_ST0,
  50 };
  51
  52 /* return registers for function */
  53 #define REG_IRET REG_EAX /* single word int return register */
  54 #define REG_LRET REG_EDX /* second word return register (for long long) */
  55 #define REG_FRET REG_ST0 /* float return register */
  56
  57 /* defined if function parameters must be evaluated in reverse order */
  58 #define INVERT_FUNC_PARAMS
  59
  60 /* defined if structures are passed as pointers. Otherwise structures
  61    are directly pushed on stack. */
  62 //#define FUNC_STRUCT_PARAM_AS_PTR
  63
  64 /* pointer size, in bytes */
  65 #define PTR_SIZE 4
  66
  67 /* long double size and alignment, in bytes */
  68 #define LDOUBLE_SIZE  12
  69 #define LDOUBLE_ALIGN 4
  70
  71 /* function call context */
  72 typedef struct GFuncContext {
  73     int args_size;
  74     int func_call; /* func call type (FUNC_STDCALL or FUNC_CDECL) */
  75 } GFuncContext;
  76
  77 /******************************************************/
  78
  79 static int *func_sub_sp_ptr;
  80 static unsigned char *func_bound_ptr;
  81 static int func_ret_sub;
  82
  83 void g(int c)
  84 {
  85     *(char *)ind++ = c;
  86 }
  87
  88 void o(int c)
  89 {
  90     while (c) {
  91         g(c);
  92         c = c / 256;
  93     }
  94 }
  95
  96 void gen_le32(int c)
  97 {
  98     g(c);
  99     g(c >> 8);
 100     g(c >> 16);
 101     g(c >> 24);
 102 }
 103
 104 /* patch relocation entry with value 'val' */
 105 void greloc_patch1(Reloc *p, int val)
 106 {
 107     switch(p->type) {
 108     case RELOC_ADDR32:
 109         *(int *)p->addr = val;
 110         break;
 111     case RELOC_REL32:
 112         *(int *)p->addr = val - p->addr - 4;
 113         break;
 114     }
 115 }
 116
 117 /* output a symbol and patch all calls to it */
 118 void gsym_addr(t, a)
 119 {
 120     int n;
 121     while (t) {
 122         n = *(int *)t; /* next value */
 123         *(int *)t = a - t - 4;
 124         t = n;
 125     }
 126 }
 127
 128 void gsym(t)
 129 {
 130     gsym_addr(t, ind);
 131 }
 132
 133 /* psym is used to put an instruction with a data field which is a
 134    reference to a symbol. It is in fact the same as oad ! */
 135 #define psym oad
 136
 137 /* instruction + 4 bytes data. Return the address of the data */
 138 int oad(int c, int s)
 139 {
 140     o(c);
 141     *(int *)ind = s;
 142     s = ind;
 143     ind = ind + 4;
 144     return s;
 145 }
 146
 147 /* output constant with relocation if 'r & VT_FORWARD' is true */
 148 void gen_addr32(int r, int c)
 149 {
 150     if (!(r & VT_FORWARD)) {
 151         gen_le32(c);
 152     } else {
 153         greloc((Sym *)c, ind, RELOC_ADDR32);
 154         gen_le32(0);
 155     }
 156 }
 157
 158 /* generate a modrm reference. 'op_reg' contains the addtionnal 3
 159    opcode bits */
 160 void gen_modrm(int op_reg, int r, int c)
 161 {
 162     op_reg = op_reg << 3;
 163     if ((r & VT_VALMASK) == VT_CONST) {
 164         /* constant memory reference */
 165         o(0x05 | op_reg);
 166         gen_addr32(r, c);
 167     } else if ((r & VT_VALMASK) == VT_LOCAL) {
 168         /* currently, we use only ebp as base */
 169         if (c == (char)c) {
 170             /* short reference */
 171             o(0x45 | op_reg);
 172             g(c);
 173         } else {
 174             oad(0x85 | op_reg, c);
 175         }
 176     } else {
 177         g(0x00 | op_reg | (r & VT_VALMASK));
 178     }
 179 }
 180
 181
 182 /* load 'r' from value 'sv' */
 183 void load(int r, SValue *sv)
 184 {
 185     int v, t, ft, fc, fr;
 186     SValue v1;
 187
 188     fr = sv->r;
 189     ft = sv->t;
 190     fc = sv->c.ul;
 191
 192     v = fr & VT_VALMASK;
 193     if (fr & VT_LVAL) {
 194         if (v == VT_LLOCAL) {
 195             v1.t = VT_INT;
 196             v1.r = VT_LOCAL | VT_LVAL;
 197             v1.c.ul = fc;
 198             load(r, &v1);
 199             fr = r;
 200         }
 201         if ((ft & VT_BTYPE) == VT_FLOAT) {
 202             o(0xd9); /* flds */
 203             r = 0;
 204         } else if ((ft & VT_BTYPE) == VT_DOUBLE) {
 205             o(0xdd); /* fldl */
 206             r = 0;
 207         } else if ((ft & VT_BTYPE) == VT_LDOUBLE) {
 208             o(0xdb); /* fldt */
 209             r = 5;
 210         } else if ((ft & VT_TYPE) == VT_BYTE)
 211             o(0xbe0f);   /* movsbl */
 212         else if ((ft & VT_TYPE) == (VT_BYTE | VT_UNSIGNED))
 213             o(0xb60f);   /* movzbl */
 214         else if ((ft & VT_TYPE) == VT_SHORT)
 215             o(0xbf0f);   /* movswl */
 216         else if ((ft & VT_TYPE) == (VT_SHORT | VT_UNSIGNED))
 217             o(0xb70f);   /* movzwl */
 218         else
 219             o(0x8b);     /* movl */
 220         gen_modrm(r, fr, fc);
 221     } else {
 222         if (v == VT_CONST) {
 223             o(0xb8 + r); /* mov $xx, r */
 224             gen_addr32(fr, fc);
 225         } else if (v == VT_LOCAL) {
 226             o(0x8d); /* lea xxx(%ebp), r */
 227             gen_modrm(r, VT_LOCAL, fc);
 228         } else if (v == VT_CMP) {
 229             oad(0xb8 + r, 0); /* mov $0, r */
 230             o(0x0f); /* setxx %br */
 231             o(fc);
 232             o(0xc0 + r);
 233         } else if (v == VT_JMP || v == VT_JMPI) {
 234             t = v & 1;
 235             oad(0xb8 + r, t); /* mov $1, r */
 236             oad(0xe9, 5); /* jmp after */
 237             gsym(fc);
 238             oad(0xb8 + r, t ^ 1); /* mov $0, r */
 239         } else if (v != r) {
 240             o(0x89);
 241             o(0xc0 + r + v * 8); /* mov v, r */
 242         }
 243     }
 244 }
 245
 246 /* store register 'r' in lvalue 'v' */
 247 void store(int r, SValue *v)
 248 {
 249     int fr, bt, ft, fc;
 250
 251     ft = v->t;
 252     fc = v->c.ul;
 253     fr = v->r & VT_VALMASK;
 254     bt = ft & VT_BTYPE;
 255     /* XXX: incorrect if float reg to reg */
 256     if (bt == VT_FLOAT) {
 257         o(0xd9); /* fsts */
 258         r = 2;
 259     } else if (bt == VT_DOUBLE) {
 260         o(0xdd); /* fstpl */
 261         r = 2;
 262     } else if (bt == VT_LDOUBLE) {
 263         o(0xc0d9); /* fld %st(0) */
 264         o(0xdb); /* fstpt */
 265         r = 7;
 266     } else {
 267         if (bt == VT_SHORT)
 268             o(0x66);
 269         if (bt == VT_BYTE)
 270             o(0x88);
 271         else
 272             o(0x89);
 273     }
 274     if (fr == VT_CONST ||
 275         fr == VT_LOCAL ||
 276         (v->r & VT_LVAL)) {
 277         gen_modrm(r, v->r, fc);
 278     } else if (fr != r) {
 279         o(0xc0 + fr + r * 8); /* mov r, fr */
 280     }
 281 }
 282
 283 /* start function call and return function call context */
 284 void gfunc_start(GFuncContext *c, int func_call)
 285 {
 286     c->args_size = 0;
 287     c->func_call = func_call;
 288 }
 289
 290 /* push function parameter which is in (vtop->t, vtop->c). Stack entry
 291    is then popped. */
 292 void gfunc_param(GFuncContext *c)
 293 {
 294     int size, align, r;
 295
 296     if ((vtop->t & VT_BTYPE) == VT_STRUCT) {
 297         size = type_size(vtop->t, &align);
 298         /* align to stack align size */
 299         size = (size + 3) & ~3;
 300         /* allocate the necessary size on stack */
 301         oad(0xec81, size); /* sub $xxx, %esp */
 302         /* generate structure store */
 303         r = get_reg(RC_INT);
 304         o(0x89); /* mov %esp, r */
 305         o(0xe0 + r);
 306         vset(VT_INT, r, 0);
 307         vswap();
 308         vstore();
 309         c->args_size += size;
 310     } else if (is_float(vtop->t)) {
 311         gv(RC_FLOAT); /* only one float register */
 312         if ((vtop->t & VT_BTYPE) == VT_FLOAT)
 313             size = 4;
 314         else if ((vtop->t & VT_BTYPE) == VT_DOUBLE)
 315             size = 8;
 316         else
 317             size = 12;
 318         oad(0xec81, size); /* sub $xxx, %esp */
 319         if (size == 12)
 320             o(0x7cdb);
 321         else
 322             o(0x5cd9 + size - 4); /* fstp[s|l] 0(%esp) */
 323         g(0x24);
 324         g(0x00);
 325         c->args_size += size;
 326     } else {
 327         /* simple type (currently always same size) */
 328         /* XXX: implicit cast ? */
 329         r = gv(RC_INT);
 330         if ((vtop->t & VT_BTYPE) == VT_LLONG) {
 331             size = 8;
 332             o(0x50 + vtop->r2); /* push r */
 333         } else {
 334             size = 4;
 335         }
 336         o(0x50 + r); /* push r */
 337         c->args_size += size;
 338     }
 339     vtop--;
 340 }
 341
 342 /* generate function call with address in (vtop->t, vtop->c) and free function
 343    context. Stack entry is popped */
 344 void gfunc_call(GFuncContext *c)
 345 {
 346     int r;
 347     if ((vtop->r & (VT_VALMASK | VT_LVAL)) == VT_CONST) {
 348         /* constant case */
 349         /* forward reference */
 350         if (vtop->r & VT_FORWARD) {
 351             greloc(vtop->c.sym, ind + 1, RELOC_REL32);
 352             oad(0xe8, 0);
 353         } else {
 354             oad(0xe8, vtop->c.ul - ind - 5);
 355         }
 356     } else {
 357         /* otherwise, indirect call */
 358         r = gv(RC_INT);
 359         o(0xff); /* call *r */
 360         o(0xd0 + r);
 361     }
 362     if (c->args_size && c->func_call == FUNC_CDECL)
 363         oad(0xc481, c->args_size); /* add $xxx, %esp */
 364     vtop--;
 365 }
 366
 367 /* generate function prolog of type 't' */
 368 void gfunc_prolog(int t)
 369 {
 370     int addr, align, size, u, func_call;
 371     Sym *sym;
 372
 373     sym = sym_find((unsigned)t >> VT_STRUCT_SHIFT);
 374     func_call = sym->r;
 375     addr = 8;
 376     /* if the function returns a structure, then add an
 377        implicit pointer parameter */
 378     func_vt = sym->t;
 379     if ((func_vt & VT_BTYPE) == VT_STRUCT) {
 380         func_vc = addr;
 381         addr += 4;
 382     }
 383     /* define parameters */
 384     while ((sym = sym->next) != NULL) {
 385         u = sym->t;
 386         sym_push(sym->v & ~SYM_FIELD, u,
 387                  VT_LOCAL | VT_LVAL, addr);
 388         size = type_size(u, &align);
 389         size = (size + 3) & ~3;
 390 #ifdef FUNC_STRUCT_PARAM_AS_PTR
 391         /* structs are passed as pointer */
 392         if ((u & VT_BTYPE) == VT_STRUCT) {
 393             size = 4;
 394         }
 395 #endif
 396         addr += size;
 397     }
 398     func_ret_sub = 0;
 399     /* pascal type call ? */
 400     if (func_call == FUNC_STDCALL)
 401         func_ret_sub = addr - 8;
 402     o(0xe58955); /* push   %ebp, mov    %esp, %ebp */
 403     func_sub_sp_ptr = (int *)oad(0xec81, 0); /* sub $xxx, %esp */
 404     /* leave some room for bound checking code */
 405     if (do_bounds_check) {
 406         oad(0xb8, 0); /* lbound section pointer */
 407         oad(0xb8, 0); /* call to function */
 408         func_bound_ptr = lbounds_section->data_ptr;
 409     }
 410 }
 411
 412 /* generate function epilog */
 413 void gfunc_epilog(void)
 414 {
 415 #ifdef CONFIG_TCC_BCHECK
 416     if (do_bounds_check && func_bound_ptr != lbounds_section->data_ptr) {
 417         int saved_ind;
 418         int *bounds_ptr;
 419         /* add end of table info */
 420         bounds_ptr = (int *)lbounds_section->data_ptr;
 421         *bounds_ptr++ = 0;
 422         lbounds_section->data_ptr = (unsigned char *)bounds_ptr;
 423         /* generate bound local allocation */
 424         saved_ind = ind;
 425         ind = (int)func_sub_sp_ptr + 4;
 426         oad(0xb8, (int)func_bound_ptr); /* mov %eax, xxx */
 427         oad(0xe8, (int)__bound_local_new - ind - 5);
 428         ind = saved_ind;
 429         /* generate bound check local freeing */
 430         o(0x5250); /* save returned value, if any */
 431         oad(0xb8, (int)func_bound_ptr); /* mov %eax, xxx */
 432         oad(0xe8, (int)__bound_local_delete - ind - 5);
 433         o(0x585a); /* restore returned value, if any */
 434     }
 435 #endif
 436     o(0xc9); /* leave */
 437     if (func_ret_sub == 0) {
 438         o(0xc3); /* ret */
 439     } else {
 440         o(0xc2); /* ret n */
 441         g(func_ret_sub);
 442         g(func_ret_sub >> 8);
 443     }
 444     /* align local size to word & save local variables */
 445     *func_sub_sp_ptr = (-loc + 3) & -4;
 446 }
 447
 448 /* generate a jump to a label */
 449 int gjmp(int t)
 450 {
 451     return psym(0xe9, t);
 452 }
 453
 454 /* generate a jump to a fixed address */
 455 void gjmp_addr(int a)
 456 {
 457     oad(0xe9, a - ind - 5);
 458 }
 459
 460 /* generate a test. set 'inv' to invert test. Stack entry is popped */
 461 int gtst(int inv, int t)
 462 {
 463     int v, *p;
 464     v = vtop->r & VT_VALMASK;
 465     if (v == VT_CMP) {
 466         /* fast case : can jump directly since flags are set */
 467         g(0x0f);
 468         t = psym((vtop->c.i - 16) ^ inv, t);
 469     } else if (v == VT_JMP || v == VT_JMPI) {
 470         /* && or || optimization */
 471         if ((v & 1) == inv) {
 472             /* insert vtop->c jump list in t */
 473             p = &vtop->c.i;
 474             while (*p != 0)
 475                 p = (int *)*p;
 476             *p = t;
 477             t = vtop->c.i;
 478         } else {
 479             t = gjmp(t);
 480             gsym(vtop->c.i);
 481         }
 482     } else {
 483         if (is_float(vtop->t)) {
 484             vpushi(0);
 485             gen_op(TOK_NE);
 486         }
 487         if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_FORWARD)) == VT_CONST) {
 488             /* constant jmp optimization */
 489             if ((vtop->c.i != 0) != inv)
 490                 t = gjmp(t);
 491         } else {
 492             v = gv(RC_INT);
 493             o(0x85);
 494             o(0xc0 + v * 9);
 495             g(0x0f);
 496             t = psym(0x85 ^ inv, t);
 497         }
 498     }
 499     vtop--;
 500     return t;
 501 }
 502
 503 /* generate an integer binary operation */
 504 void gen_opi(int op)
 505 {
 506     int r, fr, opc, c;
 507
 508     switch(op) {
 509     case '+':
 510     case TOK_ADDC1: /* add with carry generation */
 511         opc = 0;
 512     gen_op8:
 513         if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_FORWARD)) == VT_CONST) {
 514             /* constant case */
 515             vswap();
 516             r = gv(RC_INT);
 517             vswap();
 518             c = vtop->c.i;
 519             if (c == (char)c) {
 520                 /* XXX: generate inc and dec for smaller code ? */
 521                 o(0x83);
 522                 o(0xc0 | (opc << 3) | r);
 523                 g(c);
 524             } else {
 525                 o(0x81);
 526                 oad(0xc0 | (opc << 3) | r, c);
 527             }
 528         } else {
 529             gv2(RC_INT, RC_INT);
 530             r = vtop[-1].r;
 531             fr = vtop[0].r;
 532             o((opc << 3) | 0x01);
 533             o(0xc0 + r + fr * 8);
 534         }
 535         vtop--;
 536         if (op >= TOK_ULT && op <= TOK_GT) {
 537             vtop--;
 538             vset(VT_INT, VT_CMP, op);
 539         }
 540         break;
 541     case '-':
 542     case TOK_SUBC1: /* sub with carry generation */
 543         opc = 5;
 544         goto gen_op8;
 545     case TOK_ADDC2: /* add with carry use */
 546         opc = 2;
 547         goto gen_op8;
 548     case TOK_SUBC2: /* sub with carry use */
 549         opc = 3;
 550         goto gen_op8;
 551     case '&':
 552         opc = 4;
 553         goto gen_op8;
 554     case '^':
 555         opc = 6;
 556         goto gen_op8;
 557     case '|':
 558         opc = 1;
 559         goto gen_op8;
 560     case '*':
 561         gv2(RC_INT, RC_INT);
 562         r = vtop[-1].r;
 563         fr = vtop[0].r;
 564         vtop--;
 565         o(0xaf0f); /* imul fr, r */
 566         o(0xc0 + fr + r * 8);
 567         break;
 568     case TOK_SHL:
 569         opc = 4;
 570         goto gen_shift;
 571     case TOK_SHR:
 572         opc = 5;
 573         goto gen_shift;
 574     case TOK_SAR:
 575         opc = 7;
 576     gen_shift:
 577         opc = 0xc0 | (opc << 3);
 578         if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_FORWARD)) == VT_CONST) {
 579             /* constant case */
 580             vswap();
 581             r = gv(RC_INT);
 582             vswap();
 583             c = vtop->c.i & 0x1f;
 584             o(0xc1); /* shl/shr/sar $xxx, r */
 585             o(opc | r);
 586             g(c);
 587         } else {
 588             /* we generate the shift in ecx */
 589             gv2(RC_INT, RC_ECX);
 590             r = vtop[-1].r;
 591             o(0xd3); /* shl/shr/sar %cl, r */
 592             o(opc | r);
 593         }
 594         vtop--;
 595         break;
 596     case '/':
 597     case TOK_UDIV:
 598     case TOK_PDIV:
 599     case '%':
 600     case TOK_UMOD:
 601     case TOK_UMULL:
 602         /* first operand must be in eax */
 603         /* XXX: need better constraint for second operand */
 604         gv2(RC_EAX, RC_ECX);
 605         r = vtop[-1].r;
 606         fr = vtop[0].r;
 607         vtop--;
 608         save_reg(REG_EDX);
 609         if (op == TOK_UMULL) {
 610             o(0xf7); /* mul fr */
 611             o(0xe0 + fr);
 612             vtop->r2 = REG_EDX;
 613             r = REG_EAX;
 614         } else {
 615             if (op == TOK_UDIV || op == TOK_UMOD) {
 616                 o(0xf7d231); /* xor %edx, %edx, div fr, %eax */
 617                 o(0xf0 + fr);
 618             } else {
 619                 o(0xf799); /* cltd, idiv fr, %eax */
 620                 o(0xf8 + fr);
 621             }
 622             if (op == '%' || op == TOK_UMOD)
 623                 r = REG_EDX;
 624             else
 625                 r = REG_EAX;
 626         }
 627         vtop->r = r;
 628         break;
 629     default:
 630         opc = 7;
 631         goto gen_op8;
 632     }
 633 }
 634
 635 /* generate a floating point operation 'v = t1 op t2' instruction. The
 636    two operands are guaranted to have the same floating point type */
 637 /* XXX: need to use ST1 too */
 638 void gen_opf(int op)
 639 {
 640     int a, ft, fc, swapped, r;
 641
 642     /* convert constants to memory references */
 643     if ((vtop[-1].r & (VT_VALMASK | VT_LVAL)) == VT_CONST) {
 644         vswap();
 645         gv(RC_FLOAT);
 646         vswap();
 647     }
 648     if ((vtop[0].r & (VT_VALMASK | VT_LVAL)) == VT_CONST)
 649         gv(RC_FLOAT);
 650
 651     /* must put at least one value in the floating point register */
 652     if ((vtop[-1].r & VT_LVAL) &&
 653         (vtop[0].r & VT_LVAL)) {
 654         vswap();
 655         gv(RC_FLOAT);
 656         vswap();
 657     }
 658     if (op >= TOK_ULT && op <= TOK_GT) {
 659         /* load on stack second operand */
 660         load(REG_ST0, vtop);
 661         save_reg(REG_EAX); /* eax is used by FP comparison code */
 662         if (op == TOK_GE || op == TOK_GT)
 663             o(0xc9d9); /* fxch %st(1) */
 664         o(0xe9da); /* fucompp */
 665         o(0xe0df); /* fnstsw %ax */
 666         if (op == TOK_EQ) {
 667             o(0x45e480); /* and $0x45, %ah */
 668             o(0x40fC80); /* cmp $0x40, %ah */
 669         } else if (op == TOK_NE) {
 670             o(0x45e480); /* and $0x45, %ah */
 671             o(0x40f480); /* xor $0x40, %ah */
 672             op = TOK_NE;
 673         } else if (op == TOK_GE || op == TOK_LE) {
 674             o(0x05c4f6); /* test $0x05, %ah */
 675             op = TOK_EQ;
 676         } else {
 677             o(0x45c4f6); /* test $0x45, %ah */
 678             op = TOK_EQ;
 679         }
 680         vtop--;
 681         vtop->r = VT_CMP;
 682         vtop->c.i = op;
 683     } else {
 684         swapped = 0;
 685         /* swap the stack if needed so that t1 is the register and t2 is
 686            the memory reference */
 687         if (vtop[-1].r & VT_LVAL) {
 688             vswap();
 689             swapped = 1;
 690         }
 691         /* no memory reference possible for long double operations */
 692         if ((vtop->t & VT_BTYPE) == VT_LDOUBLE) {
 693             load(REG_ST0, vtop);
 694             swapped = !swapped;
 695         }
 696
 697         switch(op) {
 698         default:
 699         case '+':
 700             a = 0;
 701             break;
 702         case '-':
 703             a = 4;
 704             if (swapped)
 705                 a++;
 706             break;
 707         case '*':
 708             a = 1;
 709             break;
 710         case '/':
 711             a = 6;
 712             if (swapped)
 713                 a++;
 714             break;
 715         }
 716         ft = vtop->t;
 717         fc = vtop->c.ul;
 718         if ((ft & VT_BTYPE) == VT_LDOUBLE) {
 719             o(0xde); /* fxxxp %st, %st(1) */
 720             o(0xc1 + (a << 3));
 721         } else {
 722             /* if saved lvalue, then we must reload it */
 723             r = vtop->r;
 724             if ((r & VT_VALMASK) == VT_LLOCAL) {
 725                 SValue v1;
 726                 r = get_reg(RC_INT);
 727                 v1.t = VT_INT;
 728                 v1.r = VT_LOCAL | VT_LVAL;
 729                 v1.c.ul = fc;
 730                 load(r, &v1);
 731                 fc = 0;
 732             }
 733
 734             if ((ft & VT_BTYPE) == VT_DOUBLE)
 735                 o(0xdc);
 736             else
 737                 o(0xd8);
 738             gen_modrm(a, r, fc);
 739         }
 740         vtop--;
 741     }
 742 }
 743
 744 /* FPU control word for rounding to nearest mode */
 745 /* XXX: should move that into tcc lib support code ! */
 746 static unsigned short __tcc_fpu_control = 0x137f;
 747 /* FPU control word for round to zero mode for int convertion */
 748 static unsigned short __tcc_int_fpu_control = 0x137f | 0x0c00;
 749
 750 /* convert integers to fp 't' type. Must handle 'int', 'unsigned int'
 751    and 'long long' cases. */
 752 void gen_cvt_itof(int t)
 753 {
 754     save_reg(REG_ST0);
 755     gv(RC_INT);
 756     if ((vtop->t & VT_BTYPE) == VT_LLONG) {
 757         /* signed long long to float/double/long double (unsigned case
 758            is handled generically) */
 759         o(0x50 + vtop->r2); /* push r2 */
 760         o(0x50 + (vtop->r & VT_VALMASK)); /* push r */
 761         o(0x242cdf); /* fildll (%esp) */
 762         o(0x08c483); /* add $8, %esp */
 763     } else if ((vtop->t & (VT_BTYPE | VT_UNSIGNED)) ==
 764                (VT_INT | VT_UNSIGNED)) {
 765         /* unsigned int to float/double/long double */
 766         o(0x6a); /* push $0 */
 767         g(0x00);
 768         o(0x50 + (vtop->r & VT_VALMASK)); /* push r */
 769         o(0x242cdf); /* fildll (%esp) */
 770         o(0x08c483); /* add $8, %esp */
 771     } else {
 772         /* int to float/double/long double */
 773         o(0x50 + (vtop->r & VT_VALMASK)); /* push r */
 774         o(0x2404db); /* fildl (%esp) */
 775         o(0x04c483); /* add $4, %esp */
 776     }
 777     vtop->r = REG_ST0;
 778 }
 779
 780 /* convert fp to int 't' type */
 781 /* XXX: handle long long case */
 782 void gen_cvt_ftoi(int t)
 783 {
 784     int r, r2, size;
 785
 786     gv(RC_FLOAT);
 787     if (t != VT_INT)
 788         size = 8;
 789     else
 790         size = 4;
 791
 792     oad(0x2dd9, (int)&__tcc_int_fpu_control); /* ldcw xxx */
 793     oad(0xec81, size); /* sub $xxx, %esp */
 794     if (size == 4)
 795         o(0x1cdb); /* fistpl */
 796     else
 797         o(0x3cdf); /* fistpll */
 798     o(0x24);
 799     oad(0x2dd9, (int)&__tcc_fpu_control); /* ldcw xxx */
 800     r = get_reg(RC_INT);
 801     o(0x58 + r); /* pop r */
 802     if (size == 8) {
 803         if (t == VT_LLONG) {
 804             vtop->r = r; /* mark reg as used */
 805             r2 = get_reg(RC_INT);
 806             o(0x58 + r2); /* pop r2 */
 807             vtop->r2 = r2;
 808         } else {
 809             o(0x04c483); /* add $4, %esp */
 810         }
 811     }
 812     vtop->r = r;
 813 }
 814
 815 /* convert from one floating point type to another */
 816 void gen_cvt_ftof(int t)
 817 {
 818     /* all we have to do on i386 is to put the float in a register */
 819     gv(RC_FLOAT);
 820 }
 821
 822 /* bound check support functions */
 823 #ifdef CONFIG_TCC_BCHECK
 824 /* generate first part of bounded pointer addition */
 825 void gen_bounded_ptr_add1(void)
 826 {
 827     /* prepare fast i386 function call (args in eax and edx) */
 828     gv2(RC_EAX, RC_EDX);
 829     /* save all temporary registers */
 830     vtop--;
 831     vtop->r = VT_CONST;
 832     save_regs(0);
 833 }
 834
 835 /* if deref is true, then also test dereferencing */
 836 void gen_bounded_ptr_add2(int deref)
 837 {
 838     void *func;
 839     int size, align;
 840
 841     if (deref) {
 842         size = type_size(vtop->t, &align);
 843         switch(size) {
 844         case  1: func = __bound_ptr_indir1; break;
 845         case  2: func = __bound_ptr_indir2; break;
 846         case  4: func = __bound_ptr_indir4; break;
 847         case  8: func = __bound_ptr_indir8; break;
 848         case 12: func = __bound_ptr_indir12; break;
 849         case 16: func = __bound_ptr_indir16; break;
 850         default:
 851             error("unhandled size when derefencing bounded pointer");
 852             func = NULL;
 853             break;
 854         }
 855     } else {
 856         func = __bound_ptr_add;
 857     }
 858
 859     /* do a fast function call */
 860     oad(0xe8, (int)func - ind - 5);
 861     /* return pointer is there */
 862     vtop->r = REG_EAX;
 863 }
 864 #endif
 865
 866 /* end of X86 code generator */
 867 /*************************************************************/
 868