constants.c

   1 /**
   2  * Author: Humberto Naves (hsnaves@gmail.com)
   3  */
   4
   5
   6 #include "code.h"
   7 #include "utils.h"
   8
   9 static
  10 uint32 get_constant_value (struct value *val)
  11 {
  12   if (val->type == VAL_SSAVAR)
  13     return val->val.variable->info;
  14   else
  15     return val->val.intval;
  16 }
  17
  18 static
  19 void combine_constants (struct ssavar *out, struct value *val)
  20 {
  21   uint32 constant;
  22   if (out->type == SSAVAR_UNK) return;
  23
  24   if (val->type == VAL_REGISTER) {
  25     out->type = SSAVAR_UNK;
  26     return;
  27   }
  28
  29   if (val->type == VAL_SSAVAR) {
  30     if (val->val.variable->type == SSAVAR_CONSTANTUNK)
  31       return;
  32     if (val->val.variable->type == SSAVAR_UNK) {
  33       out->type = SSAVAR_UNK;
  34       return;
  35     }
  36   }
  37
  38   constant = get_constant_value (val);
  39   if (out->type == SSAVAR_CONSTANTUNK) {
  40     out->type = SSAVAR_CONSTANT;
  41     out->info = constant;
  42   } else {
  43     if (out->info != constant)
  44       out->type = SSAVAR_UNK;
  45   }
  46 }
  47
  48 void propagate_constants (struct subroutine *sub)
  49 {
  50   list worklist = list_alloc (sub->code->lstpool);
  51   element varel;
  52
  53   varel = list_head (sub->ssavars);
  54   while (varel) {
  55     struct ssavar *var = element_getvalue (varel);
  56     var->type = SSAVAR_CONSTANTUNK;
  57     if (var->def->type == OP_ASM ||
  58         var->def->type == OP_CALL ||
  59         var->def->type == OP_START ||
  60         !(IS_BIT_SET (regmask_localvars, var->name.val.intval)))
  61       var->type = SSAVAR_UNK;
  62     else
  63       list_inserttail (worklist, var);
  64     varel = element_next (varel);
  65   }
  66
  67   while (list_size (worklist) != 0) {
  68     struct ssavar *var = list_removehead (worklist);
  69     struct ssavar temp;
  70     struct value *val;
  71     element opel;
  72
  73     if (var->type == SSAVAR_UNK) continue;
  74
  75     if (var->def->type == OP_PHI) {
  76       temp.type = SSAVAR_CONSTANTUNK;
  77
  78       opel = list_head (var->def->operands);
  79       while (opel) {
  80         val = element_getvalue (opel);
  81         combine_constants (&temp, val);
  82         opel = element_next (opel);
  83       }
  84     } else {
  85       temp.type = SSAVAR_CONSTANT;
  86
  87       opel = list_head (var->def->operands);
  88       while (opel) {
  89         val = element_getvalue (opel);
  90         if (val->type == VAL_CONSTANT) {
  91         } else if (val->type == VAL_SSAVAR) {
  92           if (val->val.variable->type == SSAVAR_UNK)
  93             temp.type = SSAVAR_UNK;
  94           else if (val->val.variable->type == SSAVAR_CONSTANTUNK &&
  95                    temp.type != SSAVAR_UNK)
  96             temp.type = SSAVAR_CONSTANTUNK;
  97         }
  98         opel = element_next (opel);
  99       }
 100
 101       if (temp.type == SSAVAR_CONSTANT) {
 102         if (var->def->type == OP_MOVE) {
 103           val = list_headvalue (var->def->operands);
 104           temp.info = get_constant_value (val);
 105           var->def->status |= OP_STAT_DEFERRED;
 106         } else if (var->def->type == OP_INSTRUCTION) {
 107           uint32 val1, val2;
 108           switch (var->def->info.iop.insn) {
 109           case I_ADD:
 110           case I_ADDU:
 111             val1 = get_constant_value (list_headvalue (var->def->operands));
 112             val2 = get_constant_value (list_tailvalue (var->def->operands));
 113             temp.info = val1 + val2;
 114             var->def->status |= OP_STAT_DEFERRED;
 115             break;
 116           case I_OR:
 117             val1 = get_constant_value (list_headvalue (var->def->operands));
 118             val2 = get_constant_value (list_tailvalue (var->def->operands));
 119             temp.info = val1 | val2;
 120             var->def->status |= OP_STAT_DEFERRED;
 121             break;
 122           default:
 123             temp.type = SSAVAR_UNK;
 124             break;
 125           }
 126         }
 127       }
 128
 129     }
 130
 131     if (temp.type != var->type) {
 132       element useel;
 133       useel = list_head (var->uses);
 134       while (useel) {
 135         struct operation *use = element_getvalue (useel);
 136         varel = list_head (use->results);
 137         while (varel) {
 138           val = element_getvalue (varel);
 139           if (val->type == VAL_SSAVAR)
 140             list_inserttail (worklist, val->val.variable);
 141           varel = element_next (varel);
 142         }
 143         useel = element_next (useel);
 144       }
 145     }
 146     var->type = temp.type;
 147     var->info = temp.info;
 148
 149   }
 150
 151   list_free (worklist);
 152 }
 153
 154