ncomp/nblock.c

   1 /***************************** ncomp/nblock.c **********************************
   2
   3         Copyright (c) 1997 A. Krall, R. Grafl, M. Gschwind, M. Probst
   4
   5         See file COPYRIGHT for information on usage and disclaimer of warranties
   6
   7         Basic block handling functions.
   8
   9         Authors: Andreas  Krall      EMAIL: cacao@complang.tuwien.ac.at
  10                  Reinhard Grafl      EMAIL: cacao@complang.tuwien.ac.at
  11
  12         Last Change: 1997/11/05
  13
  14 *******************************************************************************/
  15
  16
  17 /******************** function determine_basic_blocks **************************
  18
  19         Scans the JavaVM code of a method and marks each instruction which is the
  20         start of a basic block.
  21
  22 *******************************************************************************/
  23
  24 static void allocate_literals()
  25 {
  26         int  p, nextp;
  27         int  opcode, i;
  28
  29         p = 0;
  30         while (p < jcodelength) {
  31
  32                 opcode = jcode[p];
  33                 nextp = p + jcommandsize[opcode];
  34
  35                 switch (opcode) {
  36                         case JAVA_WIDE:
  37                                 switch (code_get_u1(p + 1)) {
  38                                         case JAVA_RET:  nextp = p + 4;
  39                                                         break;
  40                                         case JAVA_IINC: nextp = p + 6;
  41                                                         break;
  42                                         default:        nextp = p + 4;
  43                                                         break;
  44                                         }
  45                                 break;
  46
  47                         case JAVA_LOOKUPSWITCH:
  48                                 {
  49                                 s4 num;
  50
  51                                 nextp = ALIGN((p + 1), 4);
  52                                 num = code_get_u4(nextp + 4);
  53                                 nextp = nextp + 8 + 8 * num;
  54                                 break;
  55                                 }
  56
  57                         case JAVA_TABLESWITCH:
  58                                 {
  59                                 s4 num;
  60
  61                                 nextp = ALIGN ((p + 1),4);
  62                                 num = code_get_s4(nextp + 4);
  63                                 num = code_get_s4(nextp + 8) - num;
  64                                 nextp = nextp + 16 + 4 * num;
  65                                 break;
  66                                 }
  67
  68                         case JAVA_LDC1:
  69                                 i = code_get_u1(p+1);
  70                                 goto pushconstantitem;
  71                         case JAVA_LDC2:
  72                         case JAVA_LDC2W:
  73                                 i = code_get_u2(p + 1);
  74                         pushconstantitem:
  75                                 if (class_constanttype(class, i) == CONSTANT_String) {
  76                                         unicode *s;
  77                                         s = class_getconstant(class, i, CONSTANT_String);
  78                                         (void) literalstring_new(s);
  79                                         }
  80                                 break;
  81                         } /* end switch */
  82
  83                 p = nextp;
  84
  85                 } /* end while */
  86
  87 }