Annotation of gforth/engine/threaded.h, revision 1.15

1.1       anton       1: /* This file defines a number of threading schemes.
                      2: 
1.6       anton       3:   Copyright (C) 1995, 1996,1997,1999 Free Software Foundation, Inc.
1.1       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
1.7       anton      19:   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
1.1       anton      20: 
                     21: 
                     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: 
                     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.
                     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: 
                     92: */
                     93: 
                     94: #ifdef DOUBLY_INDIRECT
                     95: #  define NEXT_P0      ({cfa=*ip;})
                     96: #  define IP           (ip)
1.3       anton      97: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton      98: #  define NEXT_INST    (cfa)
                     99: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    100: #  define DEF_CA       Label ca;
1.13      anton     101: #  define NEXT_P1      ({\
1.14      anton     102:   if (cfa<=vm_prims+DOESJUMP || cfa>=vm_prims+npriminfos) \
1.13      anton     103:     fprintf(stderr,"NEXT encountered prim %p at ip=%p\n", cfa, ip); \
                    104:   ip++; ca=**cfa;})
1.1       anton     105: #  define NEXT_P2      ({goto *ca;})
1.13      anton     106: #  define EXEC(XT)     ({DEF_CA cfa=(XT);\
1.14      anton     107:   if (cfa>vm_prims+DOESJUMP && cfa<vm_prims+npriminfos) \
                    108:     fprintf(stderr,"EXEC encountered xt %p at ip=%p, vm_prims=%p, xts=%p\n", cfa, ip, vm_prims, xts); \
1.13      anton     109:  ca=**cfa; goto *ca;})
1.1       anton     110: 
                    111: #else /* !defined(DOUBLY_INDIRECT) */
                    112: 
1.3       anton     113: #if defined(DIRECT_THREADED)
                    114: 
                    115: #if THREADING_SCHEME==1
                    116: #warning direct threading scheme 1: autoinc, long latency, cfa live
1.1       anton     117: #  define NEXT_P0      ({cfa=*ip++;})
                    118: #  define IP           (ip-1)
1.3       anton     119: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     120: #  define NEXT_INST    (cfa)
                    121: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    122: #  define DEF_CA
                    123: #  define NEXT_P1
                    124: #  define NEXT_P2      ({goto *cfa;})
1.15    ! anton     125: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
1.1       anton     126: #endif
                    127: 
1.3       anton     128: #if THREADING_SCHEME==2
                    129: #warning direct threading scheme 2: autoinc, long latency, cfa dead
1.1       anton     130: #  define NEXT_P0      (ip++)
                    131: #  define IP           (ip-1)
1.3       anton     132: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     133: #  define NEXT_INST    (*(ip-1))
                    134: #  define INC_IP(const_inc)    ({ ip+=(const_inc);})
                    135: #  define DEF_CA
                    136: #  define NEXT_P1
                    137: #  define NEXT_P2      ({goto **(ip-1);})
1.15    ! anton     138: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
1.1       anton     139: #endif
                    140: 
                    141: 
1.3       anton     142: #if THREADING_SCHEME==3
                    143: #warning direct threading scheme 3: autoinc, low latency, cfa live
1.1       anton     144: #  define NEXT_P0
                    145: #  define IP           (ip)
1.3       anton     146: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     147: #  define NEXT_INST    (*ip)
                    148: #  define INC_IP(const_inc)    ({ip+=(const_inc);})
                    149: #  define DEF_CA
                    150: #  define NEXT_P1      ({cfa=*ip++;})
                    151: #  define NEXT_P2      ({goto *cfa;})
1.15    ! anton     152: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
1.1       anton     153: #endif
                    154: 
1.3       anton     155: #if THREADING_SCHEME==4
                    156: #warning direct threading scheme 4: autoinc, low latency, cfa dead
1.1       anton     157: #  define NEXT_P0
                    158: #  define IP           (ip)
1.3       anton     159: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     160: #  define NEXT_INST    (*ip)
                    161: #  define INC_IP(const_inc)    ({ ip+=(const_inc);})
                    162: #  define DEF_CA
                    163: #  define NEXT_P1
                    164: #  define NEXT_P2      ({goto **(ip++);})
1.15    ! anton     165: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
1.1       anton     166: #endif
                    167: 
1.3       anton     168: #if THREADING_SCHEME==5
                    169: #warning direct threading scheme 5: long latency, cfa live
1.1       anton     170: #  define NEXT_P0      ({cfa=*ip;})
                    171: #  define IP           (ip)
1.3       anton     172: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     173: #  define NEXT_INST    (cfa)
                    174: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    175: #  define DEF_CA
                    176: #  define NEXT_P1      (ip++)
                    177: #  define NEXT_P2      ({goto *cfa;})
1.15    ! anton     178: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
1.1       anton     179: #endif
                    180: 
1.3       anton     181: #if THREADING_SCHEME==6
                    182: #warning direct threading scheme 6: long latency, cfa dead
1.1       anton     183: #  define NEXT_P0
                    184: #  define IP           (ip)
1.3       anton     185: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     186: #  define NEXT_INST    (*ip)
                    187: #  define INC_IP(const_inc)    ({ip+=(const_inc);})
                    188: #  define DEF_CA
                    189: #  define NEXT_P1      (ip++)
                    190: #  define NEXT_P2      ({goto **(ip-1);})
1.15    ! anton     191: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
1.1       anton     192: #endif
                    193: 
                    194: 
1.3       anton     195: #if THREADING_SCHEME==7
                    196: #warning direct threading scheme 7: low latency, cfa live
1.1       anton     197: #  define NEXT_P0
                    198: #  define IP           (ip)
1.3       anton     199: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     200: #  define NEXT_INST    (*ip)
                    201: #  define INC_IP(const_inc)    ({ip+=(const_inc);})
                    202: #  define DEF_CA
                    203: #  define NEXT_P1      ({cfa=*ip++;})
                    204: #  define NEXT_P2      ({goto *cfa;})
1.15    ! anton     205: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
1.1       anton     206: #endif
                    207: 
1.3       anton     208: #if THREADING_SCHEME==8
                    209: #warning direct threading scheme 8: cfa dead, i386 hack
1.1       anton     210: #  define NEXT_P0
                    211: #  define IP           (ip)
1.3       anton     212: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     213: #  define NEXT_INST    (*IP)
                    214: #  define INC_IP(const_inc)    ({ ip+=(const_inc);})
                    215: #  define DEF_CA
                    216: #  define NEXT_P1      (ip++)
                    217: #  define NEXT_P2      ({goto **(ip-1);})
1.15    ! anton     218: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
1.1       anton     219: #endif
                    220: 
1.3       anton     221: #if THREADING_SCHEME==9
                    222: #warning direct threading scheme 9: Power/PPC hack, long latency
                    223: /* Power uses a prepare-to-branch instruction, and the latency between
                    224:    this inst and the branch is 5 cycles on a PPC604; so we utilize this
                    225:    to do some prefetching in between */
                    226: #  define NEXT_P0
                    227: #  define IP           ip
                    228: #  define SET_IP(p)    ({ip=(p); next_cfa=*ip; NEXT_P0;})
                    229: #  define NEXT_INST    (next_cfa)
                    230: #  define INC_IP(const_inc)    ({next_cfa=IP[const_inc]; ip+=(const_inc);})
1.8       anton     231: #  define DEF_CA       
                    232: #  define NEXT_P1      ({cfa=next_cfa; ip++; next_cfa=*ip;})
                    233: #  define NEXT_P2      ({goto *cfa;})
1.15    ! anton     234: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
1.3       anton     235: #  define MORE_VARS    Xt next_cfa;
                    236: #endif
1.1       anton     237: 
1.3       anton     238: #if THREADING_SCHEME==10
                    239: #warning direct threading scheme 10: plain (no attempt at scheduling)
                    240: #  define NEXT_P0
                    241: #  define IP           (ip)
                    242: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
                    243: #  define NEXT_INST    (*ip)
                    244: #  define INC_IP(const_inc)    ({ip+=(const_inc);})
                    245: #  define DEF_CA
                    246: #  define NEXT_P1
                    247: #  define NEXT_P2      ({cfa=*ip++; goto *cfa;})
1.15    ! anton     248: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
1.3       anton     249: #endif
1.1       anton     250: 
1.3       anton     251: /* direct threaded */
                    252: #else
1.1       anton     253: /* indirect THREADED  */
                    254: 
1.3       anton     255: #if THREADING_SCHEME==1
                    256: #warning indirect threading scheme 1: autoinc, long latency, cisc
1.1       anton     257: #  define NEXT_P0      ({cfa=*ip++;})
                    258: #  define IP           (ip-1)
1.3       anton     259: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     260: #  define NEXT_INST    (cfa)
                    261: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    262: #  define DEF_CA
                    263: #  define NEXT_P1
                    264: #  define NEXT_P2      ({goto **cfa;})
                    265: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
                    266: #endif
                    267: 
1.3       anton     268: #if THREADING_SCHEME==2
                    269: #warning indirect threading scheme 2: autoinc, long latency
1.1       anton     270: #  define NEXT_P0      ({cfa=*ip++;})
                    271: #  define IP           (ip-1)
1.3       anton     272: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     273: #  define NEXT_INST    (cfa)
                    274: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    275: #  define DEF_CA       Label ca;
                    276: #  define NEXT_P1      ({ca=*cfa;})
                    277: #  define NEXT_P2      ({goto *ca;})
                    278: #  define EXEC(XT)     ({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
                    279: #endif
                    280: 
                    281: 
1.3       anton     282: #if THREADING_SCHEME==3
                    283: #warning indirect threading scheme 3: autoinc, low latency, cisc
1.1       anton     284: #  define NEXT_P0
                    285: #  define IP           (ip)
1.3       anton     286: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     287: #  define NEXT_INST    (*ip)
                    288: #  define INC_IP(const_inc)    ({ip+=(const_inc);})
                    289: #  define DEF_CA
                    290: #  define NEXT_P1
                    291: #  define NEXT_P2      ({cfa=*ip++; goto **cfa;})
                    292: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
                    293: #endif
                    294: 
1.3       anton     295: #if THREADING_SCHEME==4
                    296: #warning indirect threading scheme 4: autoinc, low latency
1.1       anton     297: #  define NEXT_P0      ({cfa=*ip++;})
                    298: #  define IP           (ip-1)
1.3       anton     299: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     300: #  define NEXT_INST    (cfa)
                    301: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    302: #  define DEF_CA       Label ca;
                    303: #  define NEXT_P1      ({ca=*cfa;})
                    304: #  define NEXT_P2      ({goto *ca;})
                    305: #  define EXEC(XT)     ({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
                    306: #endif
                    307: 
                    308: 
1.3       anton     309: #if THREADING_SCHEME==5
                    310: #warning indirect threading scheme 5: long latency, cisc
1.1       anton     311: #  define NEXT_P0      ({cfa=*ip;})
                    312: #  define IP           (ip)
1.3       anton     313: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     314: #  define NEXT_INST    (cfa)
                    315: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    316: #  define DEF_CA
                    317: #  define NEXT_P1      (ip++)
                    318: #  define NEXT_P2      ({goto **cfa;})
                    319: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
                    320: #endif
                    321: 
1.3       anton     322: #if THREADING_SCHEME==6
                    323: #warning indirect threading scheme 6: long latency
1.1       anton     324: #  define NEXT_P0      ({cfa=*ip;})
                    325: #  define IP           (ip)
1.3       anton     326: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     327: #  define NEXT_INST    (cfa)
                    328: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    329: #  define DEF_CA       Label ca;
                    330: #  define NEXT_P1      ({ip++; ca=*cfa;})
                    331: #  define NEXT_P2      ({goto *ca;})
                    332: #  define EXEC(XT)     ({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
                    333: #endif
                    334: 
1.3       anton     335: #if THREADING_SCHEME==7
                    336: #warning indirect threading scheme 7: low latency
                    337: #  define NEXT_P0      ({cfa=*ip;})
                    338: #  define IP           (ip)
                    339: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
                    340: #  define NEXT_INST    (cfa)
                    341: #  define INC_IP(const_inc)    ({cfa=IP[const_inc]; ip+=(const_inc);})
                    342: #  define DEF_CA       Label ca;
                    343: #  define NEXT_P1      ({ip++; ca=*cfa;})
                    344: #  define NEXT_P2      ({goto *ca;})
                    345: #  define EXEC(XT)     ({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
                    346: #endif
1.1       anton     347: 
1.3       anton     348: #if THREADING_SCHEME==8
                    349: #warning indirect threading scheme 8: low latency,cisc
1.1       anton     350: #  define NEXT_P0
                    351: #  define IP           (ip)
1.3       anton     352: #  define SET_IP(p)    ({ip=(p); NEXT_P0;})
1.1       anton     353: #  define NEXT_INST    (*ip)
                    354: #  define INC_IP(const_inc)    ({ip+=(const_inc);})
                    355: #  define DEF_CA
                    356: #  define NEXT_P1
                    357: #  define NEXT_P2      ({cfa=*ip++; goto **cfa;})
                    358: #  define EXEC(XT)     ({cfa=(XT); goto **cfa;})
                    359: #endif
                    360: 
1.3       anton     361: /* indirect threaded */
1.1       anton     362: #endif
                    363: 
                    364: #endif /* !defined(DOUBLY_INDIRECT) */
                    365: 
                    366: #define NEXT ({DEF_CA NEXT_P1; NEXT_P2;})
1.10      anton     367: #define IPTOS NEXT_INST

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