Annotation of gforth/threading.h, revision 1.5

1.1       pazsan      1: /* This file defines a number of threading schemes.
1.2       anton       2: 
1.4       anton       3:   Copyright (C) 1995, 1996 Free Software Foundation, Inc.
1.2       anton       4: 
                      5:   This file is part of Gforth.
                      6: 
                      7:   Gforth is free software; you can redistribute it and/or
                      8:   modify it under the terms of the GNU General Public License
                      9:   as published by the Free Software Foundation; either version 2
                     10:   of the License, or (at your option) any later version.
                     11: 
                     12:   This program is distributed in the hope that it will be useful,
                     13:   but WITHOUT ANY WARRANTY; without even the implied warranty of
                     14:   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
                     15:   GNU General Public License for more details.
                     16: 
                     17:   You should have received a copy of the GNU General Public License
                     18:   along with this program; if not, write to the Free Software
                     19:   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
                     20: 
                     21: 
1.4       anton      22:   This files defines macros for threading. Many sets of macros are
                     23:   defined. Functionally they have only one difference: Some implement
                     24:   direct threading, some indirect threading. The other differences are
                     25:   just variations to help GCC generate faster code for various
                     26:   machines.
                     27: 
                     28:   (Well, to tell the truth, there actually is another functional
                     29:   difference in some pathological cases: e.g., a '!' stores into the
                     30:   cell where the next executed word comes from; or, the next word
                     31:   executed comes from the top-of-stack. These differences are one of
                     32:   the reasons why GCC cannot produce the right variation by itself. We
                     33:   chose disallowing such practices and using the added implementation
                     34:   freedom to achieve a significant speedup, because these practices
                     35:   are not common in Forth (I have never heard of or seen anyone using
                     36:   them), and it is easy to circumvent problems: A control flow change
                     37:   will flush any prefetched words; you may want to do a "0
                     38:   drop" before that to write back the top-of-stack cache.)
                     39: 
                     40:   These macro sets are used in the following ways: After translation
                     41:   to C a typical primitive looks like
                     42: 
                     43:   ...
                     44:   {
                     45:   DEF_CA
                     46:   other declarations
                     47:   NEXT_P0;
                     48:   main part of the primitive
                     49:   NEXT_P1;
                     50:   store results to stack
                     51:   NEXT_P2;
                     52:   }
                     53: 
                     54:   DEF_CA and all the NEXT_P* together must implement NEXT; In the main
                     55:   part the instruction pointer can be read with IP, changed with
                     56:   INC_IP(const_inc), and the cell right behind the presently executing
                     57:   word (i.e. the value of *IP) is accessed with NEXT_INST.
                     58: 
                     59:   If a primitive does not fall through the main part, it has to do the
                     60:   rest by itself. If it changes ip, it has to redo NEXT_P0 (perhaps we
                     61:   should define a macro SET_IP).
                     62: 
                     63:   Some primitives (execute, dodefer) do not end with NEXT, but with
                     64:   EXEC(.). If NEXT_P0 has been called earlier, it has to perform
                     65:   "ip=IP;" to ensure that ip has the right value (NEXT_P0 may change
                     66:   it).
                     67: 
                     68:   Finally, there is NEXT1_P1 and NEXT1_P2, which are parts of EXEC
                     69:   (EXEC(XT) could be defined as "cfa=XT; NEXT1_P1; NEXT1_P2;" (is this
                     70:   true?)) and are used for making docol faster.
                     71: 
                     72:   We can define the ways in which these macros are used with a regular
                     73:   expression:
                     74: 
                     75:   For a primitive
                     76: 
                     77:   DEF_CA NEXT_P0 ( IP | INC_IP | NEXT_INST | ip=...; NEXT_P0 ) * ( NEXT_P1 NEXT_P2 | EXEC(...) )
                     78: 
                     79:   For a run-time routine, e.g., docol:
                     80:   PFA1(cfa) ( NEXT_P0 NEXT | cfa=...; NEXT1_P1; NEXT1_P2 | EXEC(...) )
                     81: 
                     82:   This comment does not yet describe all the dependences that the
                     83:   macros have to satisfy.
                     84: 
1.2       anton      85:   To organize the former ifdef chaos, each path is separated
                     86:   This gives a quite impressive number of paths, but you clearly
                     87:   find things that go together.
1.4       anton      88: 
                     89:   It should be possible to organize the whole thing in a way that
                     90:   contains less redundancy and allows a simpler description.
                     91: 
1.2       anton      92: */
1.1       pazsan     93: 
                     94: #ifndef GETCFA
                     95: #  define CFA_NEXT
                     96: #endif
                     97: 
1.5     ! anton      98: #ifdef DOUBLY_INDIRECT
        !            99: #  define NEXT_P0      ({cfa=*ip;})
        !           100: #  define IP           (ip)
        !           101: #  define NEXT_INST    (cfa)
        !           102: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
        !           103: #  define DEF_CA       Label ca;
        !           104: #  define NEXT_P1      ({ip++; ca=**cfa;})
        !           105: #  define NEXT_P2      ({goto *ca;})
        !           106: #  define EXEC(XT)     ({DEF_CA cfa=(XT); ca=**cfa; goto *ca;})
        !           107: #  define NEXT1_P1 ({ca = **cfa;})
        !           108: #  define NEXT1_P2 ({goto *ca;})
        !           109: 
        !           110: #else /* !defined(DOUBLY_INDIRECT) */
        !           111: 
1.1       pazsan    112: #if defined(DIRECT_THREADED) && defined(AUTO_INCREMENT)\
                    113:     && defined(LONG_LATENCY) && defined(CFA_NEXT)
                    114: #warning scheme 1
                    115: #  define NEXT_P0      ({cfa=*ip++;})
                    116: #  define IP           (ip-1)
                    117: #  define NEXT_INST    (cfa)
                    118: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    119: #  define DEF_CA
                    120: #  define NEXT_P1
                    121: #  define NEXT_P2      ({goto *cfa;})
                    122: #  define EXEC(XT)     ({cfa=(XT); goto *cfa;})
                    123: #endif
                    124: 
                    125: #if defined(DIRECT_THREADED) && defined(AUTO_INCREMENT)\
                    126:     && defined(LONG_LATENCY) && !defined(CFA_NEXT)
                    127: #warning scheme 2
                    128: #  define NEXT_P0      (ip++)
                    129: #  define IP           (ip-1)
                    130: #  define NEXT_INST    (*(ip-1))
                    131: #  define INC_IP(const_inc)    ({ ip+=(const_inc);})
                    132: #  define DEF_CA
                    133: #  define NEXT_P1
                    134: #  define NEXT_P2      ({goto **(ip-1);})
                    135: #  define EXEC(XT)     ({goto *(XT);})
                    136: #endif
                    137: 
                    138: 
                    139: #if defined(DIRECT_THREADED) && defined(AUTO_INCREMENT)\
                    140:     && !defined(LONG_LATENCY) && defined(CFA_NEXT)
                    141: #warning scheme 3
                    142: #  define NEXT_P0
                    143: #  define IP           (ip)
                    144: #  define NEXT_INST    (*ip)
                    145: #  define INC_IP(const_inc)    ({ip+=(const_inc);})
                    146: #  define DEF_CA
                    147: #  define NEXT_P1      ({cfa=*ip++;})
                    148: #  define NEXT_P2      ({goto *cfa;})
                    149: #  define EXEC(XT)     ({cfa=(XT); goto *cfa;})
                    150: #endif
                    151: 
                    152: #if defined(DIRECT_THREADED) && defined(AUTO_INCREMENT)\
                    153:     && !defined(LONG_LATENCY) && !defined(CFA_NEXT)
                    154: #warning scheme 4
                    155: #  define NEXT_P0
                    156: #  define IP           (ip)
                    157: #  define NEXT_INST    (*ip)
                    158: #  define INC_IP(const_inc)    ({ ip+=(const_inc);})
                    159: #  define DEF_CA
                    160: #  define NEXT_P1
                    161: #  define NEXT_P2      ({goto **(ip++);})
                    162: #  define EXEC(XT)     ({goto *(XT);})
                    163: #endif
                    164: 
                    165: /* without autoincrement */
                    166: 
                    167: #if defined(DIRECT_THREADED) && !defined(AUTO_INCREMENT)\
                    168:     && defined(LONG_LATENCY) && defined(CFA_NEXT)
                    169: #warning scheme 5
                    170: #  define NEXT_P0      ({cfa=*ip;})
                    171: #  define IP           (ip)
                    172: #  define NEXT_INST    (cfa)
                    173: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    174: #  define DEF_CA
                    175: #  define NEXT_P1      (ip++)
                    176: #  define NEXT_P2      ({goto *cfa;})
                    177: #  define EXEC(XT)     ({cfa=(XT); goto *cfa;})
                    178: #endif
                    179: 
                    180: #if defined(DIRECT_THREADED) && !defined(AUTO_INCREMENT)\
                    181:     && defined(LONG_LATENCY) && !defined(CFA_NEXT)
                    182: #warning scheme 6
                    183: #  define NEXT_P0
                    184: #  define IP           (ip)
                    185: #  define NEXT_INST    (*ip)
1.2       anton     186: #  define INC_IP(const_inc)    ({ip+=(const_inc);})
1.1       pazsan    187: #  define DEF_CA
                    188: #  define NEXT_P1      (ip++)
                    189: #  define NEXT_P2      ({goto **(ip-1);})
                    190: #  define EXEC(XT)     ({goto *(XT);})
                    191: #endif
                    192: 
                    193: 
                    194: #if defined(DIRECT_THREADED) && !defined(AUTO_INCREMENT)\
                    195:     && !defined(LONG_LATENCY) && defined(CFA_NEXT)
                    196: #warning scheme 7
                    197: #  define NEXT_P0
                    198: #  define IP           (ip)
                    199: #  define NEXT_INST    (*ip)
                    200: #  define INC_IP(const_inc)    ({ip+=(const_inc);})
                    201: #  define DEF_CA
                    202: #  define NEXT_P1      ({cfa=*ip++;})
                    203: #  define NEXT_P2      ({goto *cfa;})
                    204: #  define EXEC(XT)     ({cfa=(XT); goto *cfa;})
                    205: #endif
                    206: 
                    207: #if defined(DIRECT_THREADED) && !defined(AUTO_INCREMENT)\
                    208:     && !defined(LONG_LATENCY) && !defined(CFA_NEXT)
                    209: #warning scheme 8
                    210: #  define NEXT_P0
                    211: #  define IP           (ip)
                    212: #  define NEXT_INST    (*IP)
                    213: #  define INC_IP(const_inc)    ({ ip+=(const_inc);})
                    214: #  define DEF_CA
                    215: #  define NEXT_P1      (ip++)
                    216: #  define NEXT_P2      ({goto **(ip-1);})
                    217: #  define EXEC(XT)     ({goto *(XT);})
                    218: #endif
                    219: 
                    220: /* common settings for direct THREADED */
                    221: 
                    222: 
                    223: /* indirect THREADED  */
                    224: 
                    225: #if !defined(DIRECT_THREADED) && defined(AUTO_INCREMENT)\
                    226:     && defined(LONG_LATENCY) && defined(CISC_NEXT)
                    227: #  define NEXT_P0      ({cfa=*ip++;})
                    228: #  define IP           (ip-1)
                    229: #  define NEXT_INST    (cfa)
                    230: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    231: #  define DEF_CA
                    232: #  define NEXT_P1
                    233: #  define NEXT_P2      ({goto **cfa;})
                    234: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
                    235: #endif
                    236: 
                    237: #if !defined(DIRECT_THREADED) && defined(AUTO_INCREMENT)\
                    238:     && defined(LONG_LATENCY) && !defined(CISC_NEXT)
                    239: #  define NEXT_P0      ({cfa=*ip++;})
                    240: #  define IP           (ip-1)
                    241: #  define NEXT_INST    (cfa)
                    242: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    243: #  define DEF_CA       Label ca;
                    244: #  define NEXT_P1      ({ca=*cfa;})
                    245: #  define NEXT_P2      ({goto *ca;})
                    246: #  define EXEC(XT)     ({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
                    247: #endif
                    248: 
                    249: 
                    250: #if !defined(DIRECT_THREADED) && defined(AUTO_INCREMENT)\
                    251:     && !defined(LONG_LATENCY) && defined(CISC_NEXT)
                    252: #  define NEXT_P0
                    253: #  define IP           (ip)
                    254: #  define NEXT_INST    (*ip)
                    255: #  define INC_IP(const_inc)    ({ip+=(const_inc);})
                    256: #  define DEF_CA
1.3       pazsan    257: #  define NEXT_P1
                    258: #  define NEXT_P2      ({cfa=*ip++; goto **cfa;})
1.1       pazsan    259: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
                    260: #endif
                    261: 
                    262: #if !defined(DIRECT_THREADED) && defined(AUTO_INCREMENT)\
                    263:     && !defined(LONG_LATENCY) && !defined(CISC_NEXT)
                    264: #  define NEXT_P0      ({cfa=*ip++;})
                    265: #  define IP           (ip-1)
                    266: #  define NEXT_INST    (cfa)
                    267: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    268: #  define DEF_CA       Label ca;
                    269: #  define NEXT_P1      ({ca=*cfa;})
                    270: #  define NEXT_P2      ({goto *ca;})
                    271: #  define EXEC(XT)     ({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
                    272: #endif
                    273: 
                    274: 
                    275: /* without autoincrement */
                    276: 
                    277: #if !defined(DIRECT_THREADED) && !defined(AUTO_INCREMENT)\
                    278:     && defined(LONG_LATENCY) && defined(CISC_NEXT)
                    279: #  define NEXT_P0      ({cfa=*ip;})
                    280: #  define IP           (ip)
                    281: #  define NEXT_INST    (cfa)
                    282: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    283: #  define DEF_CA
                    284: #  define NEXT_P1      (ip++)
                    285: #  define NEXT_P2      ({goto **cfa;})
                    286: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
                    287: #endif
                    288: 
                    289: #if !defined(DIRECT_THREADED) && !defined(AUTO_INCREMENT)\
                    290:     && defined(LONG_LATENCY) && !defined(CISC_NEXT)
                    291: #  define NEXT_P0      ({cfa=*ip;})
                    292: #  define IP           (ip)
                    293: #  define NEXT_INST    (cfa)
                    294: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    295: #  define DEF_CA       Label ca;
                    296: #  define NEXT_P1      ({ip++; ca=*cfa;})
                    297: #  define NEXT_P2      ({goto *ca;})
                    298: #  define EXEC(XT)     ({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
                    299: #endif
                    300: 
                    301: 
                    302: #if !defined(DIRECT_THREADED) && !defined(AUTO_INCREMENT)\
                    303:     && !defined(LONG_LATENCY) && defined(CISC_NEXT)
                    304: #  define NEXT_P0
                    305: #  define IP           (ip)
                    306: #  define NEXT_INST    (*ip)
                    307: #  define INC_IP(const_inc)    ({ip+=(const_inc);})
                    308: #  define DEF_CA
1.3       pazsan    309: #  define NEXT_P1
                    310: #  define NEXT_P2      ({cfa=*ip++; goto **cfa;})
1.1       pazsan    311: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
                    312: #endif
                    313: 
                    314: #if !defined(DIRECT_THREADED) && !defined(AUTO_INCREMENT)\
                    315:     && !defined(LONG_LATENCY) && !defined(CISC_NEXT)
                    316: #  define NEXT_P0      ({cfa=*ip;})
                    317: #  define IP           (ip)
                    318: #  define NEXT_INST    (cfa)
                    319: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    320: #  define DEF_CA       Label ca;
                    321: #  define NEXT_P1      ({ip++; ca=*cfa;})
                    322: #  define NEXT_P2      ({goto *ca;})
                    323: #  define EXEC(XT)     ({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
                    324: #endif
                    325: 
                    326: #if defined(CISC_NEXT) && !defined(LONG_LATENCY)
                    327: # define NEXT1_P1
                    328: # ifdef DIRECT_THREADED
                    329: #  define NEXT1_P2 ({goto *cfa;})
                    330: # else
                    331: #  define NEXT1_P2 ({goto **cfa;})
                    332: # endif /* DIRECT_THREADED */
1.5     ! anton     333: #else /* !defined(CISC_NEXT) || defined(LONG_LATENCY) */
1.1       pazsan    334: # ifdef DIRECT_THREADED
                    335: #  define NEXT1_P1
                    336: #  define NEXT1_P2 ({goto *cfa;})
1.5     ! anton     337: # else /* !DIRECT_THREADED */
1.1       pazsan    338: #  define NEXT1_P1 ({ca = *cfa;})
                    339: #  define NEXT1_P2 ({goto *ca;})
1.5     ! anton     340: # endif /* !DIRECT_THREADED */
        !           341: #endif /* !defined(CISC_NEXT) || defined(LONG_LATENCY) */
        !           342: 
        !           343: #endif /* !defined(DOUBLY_INDIRECT) */
        !           344: 
        !           345: #define NEXT ({DEF_CA NEXT_P1; NEXT_P2;})
        !           346: 

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