constants.c

   1
   2
   3 #include "code.h"
   4 #include "utils.h"
   5
   6 static
   7 uint32 get_constant_value (struct value *val)
   8 {
   9   if (val->type == VAL_SSAVAR)
  10     return val->val.variable->info;
  11   else
  12     return val->val.intval;
  13 }
  14
  15 static
  16 void combine_constants (struct ssavar *out, struct value *val)
  17 {
  18   uint32 constant;
  19   if (out->type == SSAVAR_UNK) return;
  20
  21   if (val->type == VAL_REGISTER) {
  22     out->type = SSAVAR_UNK;
  23     return;
  24   }
  25
  26   if (val->type == VAL_SSAVAR) {
  27     if (val->val.variable->type == SSAVAR_CONSTANTUNK)
  28       return;
  29     if (val->val.variable->type == SSAVAR_UNK) {
  30       out->type = SSAVAR_UNK;
  31       return;
  32     }
  33   }
  34
  35   constant = get_constant_value (val);
  36   if (out->type == SSAVAR_CONSTANTUNK) {
  37     out->type = SSAVAR_CONSTANT;
  38     out->info = constant;
  39   } else {
  40     if (out->info != constant)
  41       out->type = SSAVAR_UNK;
  42   }
  43 }
  44
  45 void propagate_constants (struct subroutine *sub)
  46 {
  47   list worklist = list_alloc (sub->code->lstpool);
  48   element varel;
  49
  50   varel = list_head (sub->ssavars);
  51   while (varel) {
  52     struct ssavar *var = element_getvalue (varel);
  53     var->type = SSAVAR_CONSTANTUNK;
  54     if (var->def->type == OP_ASM ||
  55         var->def->type == OP_CALL ||
  56         var->def->type == OP_START ||
  57         !(IS_BIT_SET (regmask_localvars, var->name.val.intval)))
  58       var->type = SSAVAR_UNK;
  59     else
  60       list_inserttail (worklist, var);
  61     varel = element_next (varel);
  62   }
  63
  64   while (list_size (worklist) != 0) {
  65     struct ssavar *var = list_removehead (worklist);
  66     struct ssavar temp;
  67     struct value *val;
  68     element opel;
  69
  70     if (var->type == SSAVAR_UNK) continue;
  71
  72     if (var->def->type == OP_PHI) {
  73       temp.type = SSAVAR_CONSTANTUNK;
  74
  75       opel = list_head (var->def->operands);
  76       while (opel) {
  77         val = element_getvalue (opel);
  78         combine_constants (&temp, val);
  79         opel = element_next (opel);
  80       }
  81     } else {
  82       temp.type = SSAVAR_CONSTANT;
  83
  84       opel = list_head (var->def->operands);
  85       while (opel) {
  86         val = element_getvalue (opel);
  87         if (val->type == VAL_CONSTANT) {
  88         } else if (val->type == VAL_SSAVAR) {
  89           if (val->val.variable->type == SSAVAR_UNK)
  90             temp.type = SSAVAR_UNK;
  91           else if (val->val.variable->type == SSAVAR_CONSTANTUNK &&
  92                    temp.type != SSAVAR_UNK)
  93             temp.type = SSAVAR_CONSTANTUNK;
  94         }
  95         opel = element_next (opel);
  96       }
  97
  98       if (temp.type == SSAVAR_CONSTANT) {
  99         if (var->def->type == OP_MOVE) {
 100           val = list_headvalue (var->def->operands);
 101           temp.info = get_constant_value (val);
 102           var->def->status |= OPERATION_DEFERRED;
 103         } else if (var->def->type == OP_INSTRUCTION) {
 104           uint32 val1, val2;
 105           switch (var->def->info.iop.insn) {
 106           case I_ADD:
 107           case I_ADDU:
 108             val1 = get_constant_value (list_headvalue (var->def->operands));
 109             val2 = get_constant_value (list_tailvalue (var->def->operands));
 110             temp.info = val1 + val2;
 111             var->def->status |= OPERATION_DEFERRED;
 112             break;
 113           case I_OR:
 114             val1 = get_constant_value (list_headvalue (var->def->operands));
 115             val2 = get_constant_value (list_tailvalue (var->def->operands));
 116             temp.info = val1 | val2;
 117             var->def->status |= OPERATION_DEFERRED;
 118             break;
 119           default:
 120             temp.type = SSAVAR_UNK;
 121             break;
 122           }
 123         }
 124       }
 125
 126     }
 127
 128     if (temp.type != var->type) {
 129       element useel;
 130       useel = list_head (var->uses);
 131       while (useel) {
 132         struct operation *use = element_getvalue (useel);
 133         varel = list_head (use->results);
 134         while (varel) {
 135           val = element_getvalue (varel);
 136           if (val->type == VAL_SSAVAR)
 137             list_inserttail (worklist, val->val.variable);
 138           varel = element_next (varel);
 139         }
 140         useel = element_next (useel);
 141       }
 142     }
 143     var->type = temp.type;
 144     var->info = temp.info;
 145
 146   }
 147
 148   list_free (worklist);
 149 }
 150
 151