File:  [gforth] / gforth / engine / threaded.h
Revision 1.3: download - view: text, annotated - select for diffs
Sat Feb 6 22:28:25 1999 UTC (21 years, 8 months ago) by anton
Branches: MAIN
CVS tags: HEAD
cleaned up threading stuff:
  now the schemes are selected with -DTHREADED_SCHEME=n
  there is now a macro SET_IP for setting ip.
New threading schemes: for Power (20% speedup on 604e) and a plain scheme

    1: /* This file defines a number of threading schemes.
    2: 
    3:   Copyright (C) 1995, 1996,1997 Free Software Foundation, Inc.
    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: 
   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: #ifndef GETCFA
   95: #  define CFA_NEXT
   96: /* a more appropriate name would be CFA_LIVE, i.e., cfa is live after NEXT */
   97: #endif
   98: 
   99: #ifdef DOUBLY_INDIRECT
  100: #  define NEXT_P0	({cfa=*ip;})
  101: #  define IP		(ip)
  102: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  103: #  define NEXT_INST	(cfa)
  104: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  105: #  define DEF_CA	Label ca;
  106: #  define NEXT_P1	({ip++; ca=**cfa;})
  107: #  define NEXT_P2	({goto *ca;})
  108: #  define EXEC(XT)	({DEF_CA cfa=(XT); ca=**cfa; goto *ca;})
  109: #  define NEXT1_P1 ({ca = **cfa;})
  110: #  define NEXT1_P2 ({goto *ca;})
  111: 
  112: #else /* !defined(DOUBLY_INDIRECT) */
  113: 
  114: #if defined(DIRECT_THREADED)
  115: 
  116: /* note that the "cfa dead" versions only work if GETCFA exists and works */
  117: 
  118: #if THREADING_SCHEME==1
  119: #warning direct threading scheme 1: autoinc, long latency, cfa live
  120: #  define NEXT_P0	({cfa=*ip++;})
  121: #  define IP		(ip-1)
  122: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  123: #  define NEXT_INST	(cfa)
  124: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  125: #  define DEF_CA
  126: #  define NEXT_P1
  127: #  define NEXT_P2	({goto *cfa;})
  128: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  129: #endif
  130: 
  131: #if THREADING_SCHEME==2
  132: #warning direct threading scheme 2: autoinc, long latency, cfa dead
  133: #  define NEXT_P0	(ip++)
  134: #  define IP		(ip-1)
  135: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  136: #  define NEXT_INST	(*(ip-1))
  137: #  define INC_IP(const_inc)	({ ip+=(const_inc);})
  138: #  define DEF_CA
  139: #  define NEXT_P1
  140: #  define NEXT_P2	({goto **(ip-1);})
  141: #  define EXEC(XT)	({goto *(XT);})
  142: #endif
  143: 
  144: 
  145: #if THREADING_SCHEME==3
  146: #warning direct threading scheme 3: autoinc, low latency, cfa live
  147: #  define NEXT_P0
  148: #  define IP		(ip)
  149: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  150: #  define NEXT_INST	(*ip)
  151: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  152: #  define DEF_CA
  153: #  define NEXT_P1	({cfa=*ip++;})
  154: #  define NEXT_P2	({goto *cfa;})
  155: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  156: #endif
  157: 
  158: #if THREADING_SCHEME==4
  159: #warning direct threading scheme 4: autoinc, low latency, cfa dead
  160: #  define NEXT_P0
  161: #  define IP		(ip)
  162: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  163: #  define NEXT_INST	(*ip)
  164: #  define INC_IP(const_inc)	({ ip+=(const_inc);})
  165: #  define DEF_CA
  166: #  define NEXT_P1
  167: #  define NEXT_P2	({goto **(ip++);})
  168: #  define EXEC(XT)	({goto *(XT);})
  169: #endif
  170: 
  171: #if THREADING_SCHEME==5
  172: #warning direct threading scheme 5: long latency, cfa live
  173: #  define NEXT_P0	({cfa=*ip;})
  174: #  define IP		(ip)
  175: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  176: #  define NEXT_INST	(cfa)
  177: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  178: #  define DEF_CA
  179: #  define NEXT_P1	(ip++)
  180: #  define NEXT_P2	({goto *cfa;})
  181: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  182: #endif
  183: 
  184: #if THREADING_SCHEME==6
  185: #warning direct threading scheme 6: long latency, cfa dead
  186: #  define NEXT_P0
  187: #  define IP		(ip)
  188: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  189: #  define NEXT_INST	(*ip)
  190: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  191: #  define DEF_CA
  192: #  define NEXT_P1	(ip++)
  193: #  define NEXT_P2	({goto **(ip-1);})
  194: #  define EXEC(XT)	({goto *(XT);})
  195: #endif
  196: 
  197: 
  198: #if THREADING_SCHEME==7
  199: #warning direct threading scheme 7: low latency, cfa live
  200: #  define NEXT_P0
  201: #  define IP		(ip)
  202: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  203: #  define NEXT_INST	(*ip)
  204: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  205: #  define DEF_CA
  206: #  define NEXT_P1	({cfa=*ip++;})
  207: #  define NEXT_P2	({goto *cfa;})
  208: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  209: #endif
  210: 
  211: #if THREADING_SCHEME==8
  212: #warning direct threading scheme 8: cfa dead, i386 hack
  213: #  define NEXT_P0
  214: #  define IP		(ip)
  215: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  216: #  define NEXT_INST	(*IP)
  217: #  define INC_IP(const_inc)	({ ip+=(const_inc);})
  218: #  define DEF_CA
  219: #  define NEXT_P1	(ip++)
  220: #  define NEXT_P2	({goto **(ip-1);})
  221: #  define EXEC(XT)	({goto *(XT);})
  222: #endif
  223: 
  224: #if THREADING_SCHEME==9
  225: #warning direct threading scheme 9: Power/PPC hack, long latency
  226: /* Power uses a prepare-to-branch instruction, and the latency between
  227:    this inst and the branch is 5 cycles on a PPC604; so we utilize this
  228:    to do some prefetching in between */
  229: #  define NEXT_P0
  230: #  define IP		ip
  231: #  define SET_IP(p)	({ip=(p); next_cfa=*ip; NEXT_P0;})
  232: #  define NEXT_INST	(next_cfa)
  233: #  define INC_IP(const_inc)	({next_cfa=IP[const_inc]; ip+=(const_inc);})
  234: #  define DEF_CA	Label ca;
  235: #  define NEXT_P1	({ca=next_cfa; cfa=next_cfa; ip++; next_cfa=*ip;})
  236: #  define NEXT_P2	({goto *ca;})
  237: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  238: #  define MORE_VARS	Xt next_cfa;
  239: #endif
  240: 
  241: #if THREADING_SCHEME==10
  242: #warning direct threading scheme 10: plain (no attempt at scheduling)
  243: #  define NEXT_P0
  244: #  define IP		(ip)
  245: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  246: #  define NEXT_INST	(*ip)
  247: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  248: #  define DEF_CA
  249: #  define NEXT_P1
  250: #  define NEXT_P2	({cfa=*ip++; goto *cfa;})
  251: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  252: #endif
  253: 
  254: /* direct threaded */
  255: #else
  256: /* indirect THREADED  */
  257: 
  258: #if THREADING_SCHEME==1
  259: #warning indirect threading scheme 1: autoinc, long latency, cisc
  260: #  define NEXT_P0	({cfa=*ip++;})
  261: #  define IP		(ip-1)
  262: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  263: #  define NEXT_INST	(cfa)
  264: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  265: #  define DEF_CA
  266: #  define NEXT_P1
  267: #  define NEXT_P2	({goto **cfa;})
  268: #  define EXEC(XT)	({cfa=(XT); goto **cfa;})
  269: #endif
  270: 
  271: #if THREADING_SCHEME==2
  272: #warning indirect threading scheme 2: autoinc, long latency
  273: #  define NEXT_P0	({cfa=*ip++;})
  274: #  define IP		(ip-1)
  275: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  276: #  define NEXT_INST	(cfa)
  277: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  278: #  define DEF_CA	Label ca;
  279: #  define NEXT_P1	({ca=*cfa;})
  280: #  define NEXT_P2	({goto *ca;})
  281: #  define EXEC(XT)	({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
  282: #endif
  283: 
  284: 
  285: #if THREADING_SCHEME==3
  286: #warning indirect threading scheme 3: autoinc, low latency, cisc
  287: #  define NEXT_P0
  288: #  define IP		(ip)
  289: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  290: #  define NEXT_INST	(*ip)
  291: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  292: #  define DEF_CA
  293: #  define NEXT_P1
  294: #  define NEXT_P2	({cfa=*ip++; goto **cfa;})
  295: #  define EXEC(XT)	({cfa=(XT); goto **cfa;})
  296: #endif
  297: 
  298: #if THREADING_SCHEME==4
  299: #warning indirect threading scheme 4: autoinc, low latency
  300: #  define NEXT_P0	({cfa=*ip++;})
  301: #  define IP		(ip-1)
  302: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  303: #  define NEXT_INST	(cfa)
  304: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  305: #  define DEF_CA	Label ca;
  306: #  define NEXT_P1	({ca=*cfa;})
  307: #  define NEXT_P2	({goto *ca;})
  308: #  define EXEC(XT)	({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
  309: #endif
  310: 
  311: 
  312: #if THREADING_SCHEME==5
  313: #warning indirect threading scheme 5: long latency, cisc
  314: #  define NEXT_P0	({cfa=*ip;})
  315: #  define IP		(ip)
  316: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  317: #  define NEXT_INST	(cfa)
  318: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  319: #  define DEF_CA
  320: #  define NEXT_P1	(ip++)
  321: #  define NEXT_P2	({goto **cfa;})
  322: #  define EXEC(XT)	({cfa=(XT); goto **cfa;})
  323: #endif
  324: 
  325: #if THREADING_SCHEME==6
  326: #warning indirect threading scheme 6: long latency
  327: #  define NEXT_P0	({cfa=*ip;})
  328: #  define IP		(ip)
  329: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  330: #  define NEXT_INST	(cfa)
  331: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  332: #  define DEF_CA	Label ca;
  333: #  define NEXT_P1	({ip++; ca=*cfa;})
  334: #  define NEXT_P2	({goto *ca;})
  335: #  define EXEC(XT)	({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
  336: #endif
  337: 
  338: #if THREADING_SCHEME==7
  339: #warning indirect threading scheme 7: low latency
  340: #  define NEXT_P0	({cfa=*ip;})
  341: #  define IP		(ip)
  342: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  343: #  define NEXT_INST	(cfa)
  344: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  345: #  define DEF_CA	Label ca;
  346: #  define NEXT_P1	({ip++; ca=*cfa;})
  347: #  define NEXT_P2	({goto *ca;})
  348: #  define EXEC(XT)	({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
  349: #endif
  350: 
  351: #if THREADING_SCHEME==8
  352: #warning indirect threading scheme 8: low latency,cisc
  353: #  define NEXT_P0
  354: #  define IP		(ip)
  355: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  356: #  define NEXT_INST	(*ip)
  357: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  358: #  define DEF_CA
  359: #  define NEXT_P1
  360: #  define NEXT_P2	({cfa=*ip++; goto **cfa;})
  361: #  define EXEC(XT)	({cfa=(XT); goto **cfa;})
  362: #endif
  363: 
  364: /* indirect threaded */
  365: #endif
  366: 
  367: #endif /* !defined(DOUBLY_INDIRECT) */
  368: 
  369: #define NEXT ({DEF_CA NEXT_P1; NEXT_P2;})
  370: 

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