gas.c

   1 #include "all.h"
   2
   3
   4 char *gasloc, *gassym;
   5 static int gasasm;
   6
   7 void
   8 gasinit(enum Asm asmmode)
   9 {
  10         gasasm = asmmode;
  11         switch (gasasm) {
  12         case Gaself:
  13                 gasloc = ".L";
  14                 gassym = "";
  15                 break;
  16         case Gasmacho:
  17                 gasloc = "L";
  18                 gassym = "_";
  19                 break;
  20         }
  21 }
  22
  23 void
  24 gasemitlnk(char *n, Lnk *l, char *s, FILE *f)
  25 {
  26         char *p;
  27
  28         if (l->sec) {
  29                 fprintf(f, ".section %s", l->sec);
  30                 if (l->secf)
  31                         fprintf(f, ", %s", l->secf);
  32         } else {
  33                 fputs(s, f);
  34         }
  35         fputc('\n', f);
  36         if (l->align)
  37                 fprintf(f, ".balign %d\n", l->align);
  38         p = n[0] == '"' ? "" : gassym;
  39         if (l->export)
  40                 fprintf(f, ".globl %s%s\n", p, n);
  41         fprintf(f, "%s%s:\n", p, n);
  42 }
  43
  44 void
  45 gasemitfntail(char *fn, FILE *f)
  46 {
  47         if (gasasm == Gaself) {
  48                 fprintf(f, ".type %s, @function\n", fn);
  49                 fprintf(f, ".size %s, .-%s\n", fn, fn);
  50         }
  51 }
  52
  53 void
  54 gasemitdat(Dat *d, FILE *f)
  55 {
  56         static char *dtoa[] = {
  57                 [DB] = "\t.byte",
  58                 [DH] = "\t.short",
  59                 [DW] = "\t.int",
  60                 [DL] = "\t.quad"
  61         };
  62         static int64_t zero;
  63         char *p;
  64
  65         switch (d->type) {
  66         case DStart:
  67                 zero = 0;
  68                 break;
  69         case DEnd:
  70                 if (zero != -1) {
  71                         gasemitlnk(d->name, d->lnk, ".bss", f);
  72                         fprintf(f, "\t.fill %"PRId64",1,0\n", zero);
  73                 }
  74                 break;
  75         case DZ:
  76                 if (zero != -1)
  77                         zero += d->u.num;
  78                 else
  79                         fprintf(f, "\t.fill %"PRId64",1,0\n", d->u.num);
  80                 break;
  81         default:
  82                 if (zero != -1) {
  83                         gasemitlnk(d->name, d->lnk, ".data", f);
  84                         if (zero > 0)
  85                                 fprintf(f, "\t.fill %"PRId64",1,0\n", zero);
  86                         zero = -1;
  87                 }
  88                 if (d->isstr) {
  89                         if (d->type != DB)
  90                                 err("strings only supported for 'b' currently");
  91                         fprintf(f, "\t.ascii %s\n", d->u.str);
  92                 }
  93                 else if (d->isref) {
  94                         p = d->u.ref.name[0] == '"' ? "" : gassym;
  95                         fprintf(f, "%s %s%s%+"PRId64"\n",
  96                                 dtoa[d->type], p, d->u.ref.name,
  97                                 d->u.ref.off);
  98                 }
  99                 else {
 100                         fprintf(f, "%s %"PRId64"\n",
 101                                 dtoa[d->type], d->u.num);
 102                 }
 103                 break;
 104         }
 105 }
 106
 107 typedef struct Asmbits Asmbits;
 108
 109 struct Asmbits {
 110         char bits[16];
 111         int size;
 112         Asmbits *link;
 113 };
 114
 115 static Asmbits *stash;
 116
 117 int
 118 gasstash(void *bits, int size)
 119 {
 120         Asmbits **pb, *b;
 121         int i;
 122
 123         assert(size == 4 || size == 8 || size == 16);
 124         for (pb=&stash, i=0; (b=*pb); pb=&b->link, i++)
 125                 if (size <= b->size)
 126                 if (memcmp(bits, b->bits, size) == 0)
 127                         return i;
 128         b = emalloc(sizeof *b);
 129         memcpy(b->bits, bits, size);
 130         b->size = size;
 131         b->link = 0;
 132         *pb = b;
 133         return i;
 134 }
 135
 136 void
 137 gasemitfin(FILE *f)
 138 {
 139         Asmbits *b;
 140         char *p;
 141         int sz, i;
 142         double d;
 143
 144         if (gasasm == Gaself)
 145                 fprintf(f, ".section .note.GNU-stack,\"\",@progbits\n\n");
 146         if (!stash)
 147                 return;
 148         fprintf(f, "/* floating point constants */\n.data\n");
 149         for (sz=16; sz>=4; sz/=2)
 150                 for (b=stash, i=0; b; b=b->link, i++) {
 151                         if (b->size == sz) {
 152                                 fprintf(f,
 153                                         ".balign %d\n"
 154                                         "%sfp%d:",
 155                                         sz, gasloc, i
 156                                 );
 157                                 for (p=b->bits; p<&b->bits[sz]; p+=4)
 158                                         fprintf(f, "\n\t.int %"PRId32,
 159                                                 *(int32_t *)p);
 160                                 if (sz <= 8) {
 161                                         if (sz == 4)
 162                                                 d = *(float *)b->bits;
 163                                         else
 164                                                 d = *(double *)b->bits;
 165                                         fprintf(f, " /* %f */\n", d);
 166                                 } else
 167                                         fprintf(f, "\n");
 168                         }
 169                 }
 170         while ((b=stash)) {
 171                 stash = b->link;
 172                 free(b);
 173         }
 174 }