live.c

   1 #include "all.h"
   2
   3 void
   4 liveon(BSet *v, Blk *b, Blk *s)
   5 {
   6         Phi *p;
   7         uint a;
   8
   9         bscopy(v, s->in);
  10         for (p=s->phi; p; p=p->link)
  11                 if (rtype(p->to) == RTmp)
  12                         bsclr(v, p->to.val);
  13         for (p=s->phi; p; p=p->link)
  14                 for (a=0; a<p->narg; a++)
  15                         if (p->blk[a] == b)
  16                         if (rtype(p->arg[a]) == RTmp) {
  17                                 bsset(v, p->arg[a].val);
  18                                 bsset(b->gen, p->arg[a].val);
  19                         }
  20 }
  21
  22 static void
  23 bset(Ref r, Blk *b, int *nlv, Tmp *tmp)
  24 {
  25
  26         if (rtype(r) != RTmp)
  27                 return;
  28         bsset(b->gen, r.val);
  29         if (!bshas(b->in, r.val)) {
  30                 nlv[KBASE(tmp[r.val].cls)]++;
  31                 bsset(b->in, r.val);
  32         }
  33 }
  34
  35 /* liveness analysis
  36  * requires rpo computation
  37  */
  38 void
  39 filllive(Fn *f)
  40 {
  41         Blk *b;
  42         Ins *i;
  43         int k, t, m[2], n, chg, nlv[2];
  44         BSet u[1], v[1];
  45         Mem *ma;
  46
  47         bsinit(u, f->ntmp);
  48         bsinit(v, f->ntmp);
  49         for (b=f->start; b; b=b->link) {
  50                 bsinit(b->in, f->ntmp);
  51                 bsinit(b->out, f->ntmp);
  52                 bsinit(b->gen, f->ntmp);
  53         }
  54         chg = 1;
  55 Again:
  56         for (n=f->nblk-1; n>=0; n--) {
  57                 b = f->rpo[n];
  58
  59                 bscopy(u, b->out);
  60                 if (b->s1) {
  61                         liveon(v, b, b->s1);
  62                         bsunion(b->out, v);
  63                 }
  64                 if (b->s2) {
  65                         liveon(v, b, b->s2);
  66                         bsunion(b->out, v);
  67                 }
  68                 chg |= !bsequal(b->out, u);
  69
  70                 memset(nlv, 0, sizeof nlv);
  71                 b->out->t[0] |= T.rglob;
  72                 bscopy(b->in, b->out);
  73                 for (t=0; bsiter(b->in, &t); t++)
  74                         nlv[KBASE(f->tmp[t].cls)]++;
  75                 if (rtype(b->jmp.arg) == RCall) {
  76                         assert((int)bscount(b->in) == T.nrglob &&
  77                                 b->in->t[0] == T.rglob);
  78                         b->in->t[0] |= T.retregs(b->jmp.arg, nlv);
  79                 } else
  80                         bset(b->jmp.arg, b, nlv, f->tmp);
  81                 for (k=0; k<2; k++)
  82                         b->nlive[k] = nlv[k];
  83                 for (i=&b->ins[b->nins]; i!=b->ins;) {
  84                         if ((--i)->op == Ocall && rtype(i->arg[1]) == RCall) {
  85                                 b->in->t[0] &= ~T.retregs(i->arg[1], m);
  86                                 for (k=0; k<2; k++) {
  87                                         nlv[k] -= m[k];
  88                                         /* caller-save registers are used
  89                                          * by the callee, in that sense,
  90                                          * right in the middle of the call,
  91                                          * they are live: */
  92                                         nlv[k] += T.nrsave[k];
  93                                         if (nlv[k] > b->nlive[k])
  94                                                 b->nlive[k] = nlv[k];
  95                                 }
  96                                 b->in->t[0] |= T.argregs(i->arg[1], m);
  97                                 for (k=0; k<2; k++) {
  98                                         nlv[k] -= T.nrsave[k];
  99                                         nlv[k] += m[k];
 100                                 }
 101                         }
 102                         if (!req(i->to, R)) {
 103                                 assert(rtype(i->to) == RTmp);
 104                                 t = i->to.val;
 105                                 if (bshas(b->in, t))
 106                                         nlv[KBASE(f->tmp[t].cls)]--;
 107                                 bsset(b->gen, t);
 108                                 bsclr(b->in, t);
 109                         }
 110                         for (k=0; k<2; k++)
 111                                 switch (rtype(i->arg[k])) {
 112                                 case RMem:
 113                                         ma = &f->mem[i->arg[k].val];
 114                                         bset(ma->base, b, nlv, f->tmp);
 115                                         bset(ma->index, b, nlv, f->tmp);
 116                                         break;
 117                                 default:
 118                                         bset(i->arg[k], b, nlv, f->tmp);
 119                                         break;
 120                                 }
 121                         for (k=0; k<2; k++)
 122                                 if (nlv[k] > b->nlive[k])
 123                                         b->nlive[k] = nlv[k];
 124                 }
 125         }
 126         if (chg) {
 127                 chg = 0;
 128                 goto Again;
 129         }
 130
 131         if (debug['L']) {
 132                 fprintf(stderr, "\n> Liveness analysis:\n");
 133                 for (b=f->start; b; b=b->link) {
 134                         fprintf(stderr, "\t%-10sin:   ", b->name);
 135                         dumpts(b->in, f->tmp, stderr);
 136                         fprintf(stderr, "\t          out:  ");
 137                         dumpts(b->out, f->tmp, stderr);
 138                         fprintf(stderr, "\t          gen:  ");
 139                         dumpts(b->gen, f->tmp, stderr);
 140                         fprintf(stderr, "\t          live: ");
 141                         fprintf(stderr, "%d %d\n", b->nlive[0], b->nlive[1]);
 142                 }
 143         }
 144 }