gcc/bi-run.h

   1 /* Definitions for Bytecode Interpreter.
   2    Copyright (C) 1993, 1994 Free Software Foundation, Inc.
   3
   4 This file is part of GNU CC.
   5
   6 GNU CC is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU CC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU CC; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20 #define MAXLITERALS 5
  21
  22 struct arityvec
  23 {
  24   char ninputs;
  25   char noutputs;
  26   char nliterals;
  27   char literals[MAXLITERALS];
  28 };
  29
  30 struct argtype
  31 {
  32   int modealign;                /* Argument mode:alignment */
  33   int size;                     /* Argument size, in bytes */
  34 };
  35
  36 struct callinfo
  37 {
  38   int nargs;                    /* Number of arguments in call */
  39   struct argtype retvaltype;    /* Type of return value */
  40   struct argtype argtypes[1];   /* Argument types */
  41 };
  42
  43 /* Structure describing a bytecode function.  If this changes, we also
  44    need to change expand_function_end () in bc-trans.c  */
  45 struct bytecode
  46 {
  47   int stacksize;                /* Depth required of evaluation stack.  */
  48   int localsize;                /* Size in bytes of local variables.  */
  49   unsigned char *pc0;           /* Initial program counter. */
  50   void **ptrlit;                /* Vector of (relocatable) pointer literals. */
  51   struct callinfo *callinfo;    /* Vector of procedure call type info. */
  52 };
  53
  54
  55 #define INTERP_BPC 8            /* Bits per char */
  56 #define INTERP_BPI \
  57   (sizeof (int) * INTERP_BPC)   /* Bits per int */
  58
  59
  60 #ifndef min
  61 #define min(L, R)  ((L) < (R) ? (L) : (R))
  62 #endif
  63
  64
  65 /* bit field operations. */
  66
  67 /* Low (high) mask: int with low (high) N bits set */
  68
  69 #define LM(N)   ((1 << (N)) - 1)
  70 #define HM(N)   ((~LM (INTERP_BPI - (N))))
  71
  72
  73 /* Sign-extend SIZE low bits of VALUE to integer (typeof VALUE)
  74    Signed bitfields are loaded from memory by the sxloadBI instruction,
  75    which first retrieves the bitfield with XFIELD and then sign extends
  76    it to an SItype. */
  77
  78 #define EXTEND(SIZE, VALUE)                                                   \
  79   ({ SUtype value = (SUtype) (VALUE);                                         \
  80     (value & (1 << ((SIZE) - 1)) ? value | ~LM (SIZE) : value); })
  81
  82
  83 /* Given OFFSET:SIZE for  a bitfield, calculate:
  84
  85    [1] BYTE_OFFSET  = the byte offset of the bit field.
  86    [2] BIT_OFFSET   = the bit offset of the bit field (less than INTERP_BPC).
  87    [3] NBYTES       = the number of integral bytes in the bit field.
  88    [4] TRAILING_BITS= the number of trailing bits (less than INTERP_BPC).
  89
  90
  91    ,        ,        ,        ,        ,    (memory bytes)
  92                     ----------------        (bitfield)
  93    |        |       ||        |    |        (divisions)
  94         ^         ^       ^      ^
  95         |         |       |      |__ [4]  (bits)
  96         |         |       |_________ [3]  (bytes)
  97         |         |_________________ [2]  (bits)
  98         |___________________________ [1]  (bytes)
  99
 100
 101    The above applies to BYTE_LOW_ENDIAN machines. In BYTE_BIG_ENDIAN machines, the
 102    bit numbering is reversed (i.e. bit 0 is the sign bit).
 103
 104    (Alright, so I drew this to keep my tongue in cheek while writing the code below,
 105     not because I'm into ASCII art.) */
 106
 107
 108 #define BI_PARAMS(OFFSET, SIZE, BYTE_OFFSET, BIT_OFFSET, NBYTES, TRAILING_BITS)         \
 109   { BYTE_OFFSET = (OFFSET) / (INTERP_BPC);                              \
 110     BIT_OFFSET = (OFFSET) % (INTERP_BPC);                               \
 111     NBYTES = ((SIZE) - (INTERP_BPC - (BIT_OFFSET))) / INTERP_BPC;       \
 112     if ((NBYTES) < 0 || ((NBYTES) > 64))                                \
 113       NBYTES = 0;                                                       \
 114     if ((SIZE) + (BIT_OFFSET) <= INTERP_BPC)                            \
 115       TRAILING_BITS = 0;                                                \
 116     else                                                                \
 117       TRAILING_BITS = ((SIZE) - (INTERP_BPC - (BIT_OFFSET))) % INTERP_BPC; }
 118
 119
 120 /* SHIFT_IN_BITS retrieves NBITS bits from SOURCE and shifts into
 121    DEST. The bit field starts OFFSET bits into SOURCE.
 122
 123    OR_IN_BITS copies the NBITS low bits from VALUE into a the bitfield in
 124    DEST offset by OFFSET bits. */
 125
 126
 127 #if BYTES_BIG_ENDIAN
 128
 129 #define SHIFT_IN_BITS(DEST, SOURCE, OFFSET, NBITS)              \
 130   (DEST = ((DEST) << (NBITS))                                   \
 131    | (LM ((NBITS))                                              \
 132       & ((SOURCE) >> (INTERP_BPC - (OFFSET) - (NBITS)))))
 133
 134 #define OR_IN_BITS(DEST, VALUE, OFFSET, NBITS)                  \
 135   (DEST = ((DEST) & ~(LM ((NBITS)) << (INTERP_BPC - (OFFSET) - (NBITS))))       \
 136    | (((VALUE) & LM ((NBITS))) << (INTERP_BPC - (OFFSET) - (NBITS))))
 137
 138 #else
 139
 140 #define SHIFT_IN_BITS(DEST, SOURCE, OFFSET, NBITS)              \
 141   (DEST = ((DEST) << (NBITS))                                   \
 142    | (LM ((NBITS))                                              \
 143       & ((SOURCE) >> (OFFSET))))
 144
 145 #define OR_IN_BITS(DEST, VALUE, OFFSET, NBITS)                  \
 146   (DEST = ((DEST) & ~(LM ((NBITS)) << (OFFSET)))                \
 147    | (((VALUE) & LM ((NBITS))) << (OFFSET)))
 148
 149 #endif
 150
 151
 152 /* Procedure call; arguments are a pointer to the function to be called,
 153    a pointer to a place to store the return value, a pointer to a vector
 154    describing the type of procedure call, and the interpreter's stack pointer,
 155    which will point to the first of the arguments at this point.  */
 156
 157 #define CALL(FUNC, CALLDESC, RETVAL, SP) __call(FUNC, CALLDESC, RETVAL, SP)
 158
 159
 160 /* Procedure return; arguments are a pointer to the calldesc for this
 161    function, and a pointer to the place where the value to be returned
 162    may be found.  Generally the MACHARGS above contain a machine dependent
 163    cookie that is used to determine where to jump to.  */
 164
 165 #define PROCRET(CALLDESC, RETVAL) return