gas.c

   1 #include "all.h"
   2
   3
   4 char *gasloc, *gassym;
   5
   6 void
   7 gasemitdat(Dat *d, FILE *f)
   8 {
   9         static int aligned;
  10         static char *dtoa[] = {
  11                 [DAlign] = ".balign",
  12                 [DB] = "\t.byte",
  13                 [DH] = "\t.short",
  14                 [DW] = "\t.int",
  15                 [DL] = "\t.quad"
  16         };
  17         char *p;
  18
  19         switch (d->type) {
  20         case DStart:
  21                 aligned = 0;
  22                 if (d->u.str) {
  23                         fprintf(f, ".section %s\n", d->u.str);
  24                 } else {
  25                         fprintf(f, ".data\n");
  26                 }
  27                 break;
  28         case DEnd:
  29                 break;
  30         case DName:
  31                 if (!aligned)
  32                         fprintf(f, ".balign 8\n");
  33                 p = d->u.str[0] == '"' ? "" : gassym;
  34                 if (d->export)
  35                         fprintf(f, ".globl %s%s\n", p, d->u.str);
  36                 fprintf(f, "%s%s:\n", p, d->u.str);
  37                 break;
  38         case DZ:
  39                 fprintf(f, "\t.fill %"PRId64",1,0\n", d->u.num);
  40                 break;
  41         default:
  42                 if (d->type == DAlign)
  43                         aligned = 1;
  44
  45                 if (d->isstr) {
  46                         if (d->type != DB)
  47                                 err("strings only supported for 'b' currently");
  48                         fprintf(f, "\t.ascii %s\n", d->u.str);
  49                 }
  50                 else if (d->isref) {
  51                         p = d->u.ref.nam[0] == '"' ? "" : gassym;
  52                         fprintf(f, "%s %s%s%+"PRId64"\n",
  53                                 dtoa[d->type], p, d->u.ref.nam,
  54                                 d->u.ref.off);
  55                 }
  56                 else {
  57                         fprintf(f, "%s %"PRId64"\n",
  58                                 dtoa[d->type], d->u.num);
  59                 }
  60                 break;
  61         }
  62 }
  63
  64 typedef struct Asmbits Asmbits;
  65
  66 struct Asmbits {
  67         char bits[16];
  68         int size;
  69         Asmbits *link;
  70 };
  71
  72 static Asmbits *stash;
  73
  74 int
  75 gasstash(void *bits, int size)
  76 {
  77         Asmbits **pb, *b;
  78         int i;
  79
  80         assert(size == 4 || size == 8 || size == 16);
  81         for (pb=&stash, i=0; (b=*pb); pb=&b->link, i++)
  82                 if (size <= b->size)
  83                 if (memcmp(bits, b->bits, size) == 0)
  84                         return i;
  85         b = emalloc(sizeof *b);
  86         memcpy(b->bits, bits, size);
  87         b->size = size;
  88         b->link = 0;
  89         *pb = b;
  90         return i;
  91 }
  92
  93 void
  94 gasemitfin(FILE *f)
  95 {
  96         Asmbits *b;
  97         char *p;
  98         int sz, i;
  99         double d;
 100
 101         if (!stash)
 102                 return;
 103         fprintf(f, "/* floating point constants */\n.data\n");
 104         for (sz=16; sz>=4; sz/=2)
 105                 for (b=stash, i=0; b; b=b->link, i++) {
 106                         if (b->size == sz) {
 107                                 fprintf(f,
 108                                         ".balign %d\n"
 109                                         "%sfp%d:",
 110                                         sz, gasloc, i
 111                                 );
 112                                 for (p=b->bits; p<&b->bits[sz]; p+=4)
 113                                         fprintf(f, "\n\t.int %"PRId32,
 114                                                 *(int32_t *)p);
 115                                 if (sz <= 8) {
 116                                         if (sz == 4)
 117                                                 d = *(float *)b->bits;
 118                                         else
 119                                                 d = *(double *)b->bits;
 120                                         fprintf(f, " /* %f */\n", d);
 121                                 } else
 122                                         fprintf(f, "\n");
 123                         }
 124                 }
 125         while ((b=stash)) {
 126                 stash = b->link;
 127                 free(b);
 128         }
 129         fprintf(f, ".section .note.GNU-stack,\"\",@progbits\n");
 130 }