File:  [gforth] / gforth / engine / threaded.h
Revision 1.4: download - view: text, annotated - select for diffs
Tue May 4 12:51:35 1999 UTC (21 years, 5 months ago) by jwilke
Branches: MAIN
CVS tags: HEAD
CFA_NEXT is now defined by the threading scheme and not when GETCFA is
missing. With Gforth-debug we might have GETCFA defined and a threading
with cfa alive.
With this fix I managed to compile gforth on a system that claims it is
a 386 (i386-solaris, BTW: it is a PII...). But gforth crashes
(direct threaded scheme 10) at the moment.
Perhaps Anton should take a look on it?!

    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: /* CFA_NEXT: a more appropriate name would be CFA_LIVE, i.e., cfa is live after NEXT */
   95: 
   96: #ifdef DOUBLY_INDIRECT
   97: #  define CFA_NEXT
   98: #  define NEXT_P0	({cfa=*ip;})
   99: #  define IP		(ip)
  100: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  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: 
  112: #if defined(DIRECT_THREADED)
  113: 
  114: /* note that the "cfa dead" versions only work if GETCFA exists and works */
  115: 
  116: #if THREADING_SCHEME==1
  117: #warning direct threading scheme 1: autoinc, long latency, cfa live
  118: #  define CFA_NEXT
  119: #  define NEXT_P0	({cfa=*ip++;})
  120: #  define IP		(ip-1)
  121: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  122: #  define NEXT_INST	(cfa)
  123: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  124: #  define DEF_CA
  125: #  define NEXT_P1
  126: #  define NEXT_P2	({goto *cfa;})
  127: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  128: #endif
  129: 
  130: #if THREADING_SCHEME==2
  131: #warning direct threading scheme 2: autoinc, long latency, cfa dead
  132: #ifndef GETCFA
  133: #error GETCFA must be defined for cfa dead threading
  134: #endif
  135: #  define NEXT_P0	(ip++)
  136: #  define IP		(ip-1)
  137: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  138: #  define NEXT_INST	(*(ip-1))
  139: #  define INC_IP(const_inc)	({ ip+=(const_inc);})
  140: #  define DEF_CA
  141: #  define NEXT_P1
  142: #  define NEXT_P2	({goto **(ip-1);})
  143: #  define EXEC(XT)	({goto *(XT);})
  144: #endif
  145: 
  146: 
  147: #if THREADING_SCHEME==3
  148: #warning direct threading scheme 3: autoinc, low latency, cfa live
  149: #  define CFA_NEXT
  150: #  define NEXT_P0
  151: #  define IP		(ip)
  152: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  153: #  define NEXT_INST	(*ip)
  154: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  155: #  define DEF_CA
  156: #  define NEXT_P1	({cfa=*ip++;})
  157: #  define NEXT_P2	({goto *cfa;})
  158: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  159: #endif
  160: 
  161: #if THREADING_SCHEME==4
  162: #warning direct threading scheme 4: autoinc, low latency, cfa dead
  163: #ifndef GETCFA
  164: #error GETCFA must be defined for cfa dead threading
  165: #endif
  166: #  define NEXT_P0
  167: #  define IP		(ip)
  168: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  169: #  define NEXT_INST	(*ip)
  170: #  define INC_IP(const_inc)	({ ip+=(const_inc);})
  171: #  define DEF_CA
  172: #  define NEXT_P1
  173: #  define NEXT_P2	({goto **(ip++);})
  174: #  define EXEC(XT)	({goto *(XT);})
  175: #endif
  176: 
  177: #if THREADING_SCHEME==5
  178: #warning direct threading scheme 5: long latency, cfa live
  179: #  define CFA_NEXT
  180: #  define NEXT_P0	({cfa=*ip;})
  181: #  define IP		(ip)
  182: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  183: #  define NEXT_INST	(cfa)
  184: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  185: #  define DEF_CA
  186: #  define NEXT_P1	(ip++)
  187: #  define NEXT_P2	({goto *cfa;})
  188: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  189: #endif
  190: 
  191: #if THREADING_SCHEME==6
  192: #warning direct threading scheme 6: long latency, cfa dead
  193: #ifndef GETCFA
  194: #error GETCFA must be defined for cfa dead threading
  195: #endif
  196: #  define NEXT_P0
  197: #  define IP		(ip)
  198: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  199: #  define NEXT_INST	(*ip)
  200: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  201: #  define DEF_CA
  202: #  define NEXT_P1	(ip++)
  203: #  define NEXT_P2	({goto **(ip-1);})
  204: #  define EXEC(XT)	({goto *(XT);})
  205: #endif
  206: 
  207: 
  208: #if THREADING_SCHEME==7
  209: #warning direct threading scheme 7: low latency, cfa live
  210: #  define CFA_NEXT
  211: #  define NEXT_P0
  212: #  define IP		(ip)
  213: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  214: #  define NEXT_INST	(*ip)
  215: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  216: #  define DEF_CA
  217: #  define NEXT_P1	({cfa=*ip++;})
  218: #  define NEXT_P2	({goto *cfa;})
  219: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  220: #endif
  221: 
  222: #if THREADING_SCHEME==8
  223: #warning direct threading scheme 8: cfa dead, i386 hack
  224: #ifndef GETCFA
  225: #error GETCFA must be defined for cfa dead threading
  226: #endif
  227: #  define NEXT_P0
  228: #  define IP		(ip)
  229: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  230: #  define NEXT_INST	(*IP)
  231: #  define INC_IP(const_inc)	({ ip+=(const_inc);})
  232: #  define DEF_CA
  233: #  define NEXT_P1	(ip++)
  234: #  define NEXT_P2	({goto **(ip-1);})
  235: #  define EXEC(XT)	({goto *(XT);})
  236: #endif
  237: 
  238: #if THREADING_SCHEME==9
  239: #warning direct threading scheme 9: Power/PPC hack, long latency
  240: /* Power uses a prepare-to-branch instruction, and the latency between
  241:    this inst and the branch is 5 cycles on a PPC604; so we utilize this
  242:    to do some prefetching in between */
  243: #  define CFA_NEXT
  244: #  define NEXT_P0
  245: #  define IP		ip
  246: #  define SET_IP(p)	({ip=(p); next_cfa=*ip; NEXT_P0;})
  247: #  define NEXT_INST	(next_cfa)
  248: #  define INC_IP(const_inc)	({next_cfa=IP[const_inc]; ip+=(const_inc);})
  249: #  define DEF_CA	Label ca;
  250: #  define NEXT_P1	({ca=next_cfa; cfa=next_cfa; ip++; next_cfa=*ip;})
  251: #  define NEXT_P2	({goto *ca;})
  252: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  253: #  define MORE_VARS	Xt next_cfa;
  254: #endif
  255: 
  256: #if THREADING_SCHEME==10
  257: #warning direct threading scheme 10: plain (no attempt at scheduling)
  258: #  define CFA_NEXT
  259: #  define NEXT_P0
  260: #  define IP		(ip)
  261: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  262: #  define NEXT_INST	(*ip)
  263: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  264: #  define DEF_CA
  265: #  define NEXT_P1
  266: #  define NEXT_P2	({cfa=*ip++; goto *cfa;})
  267: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  268: #endif
  269: 
  270: /* direct threaded */
  271: #else
  272: /* indirect THREADED  */
  273: 
  274: #if THREADING_SCHEME==1
  275: #warning indirect threading scheme 1: autoinc, long latency, cisc
  276: #  define CFA_NEXT
  277: #  define NEXT_P0	({cfa=*ip++;})
  278: #  define IP		(ip-1)
  279: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  280: #  define NEXT_INST	(cfa)
  281: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  282: #  define DEF_CA
  283: #  define NEXT_P1
  284: #  define NEXT_P2	({goto **cfa;})
  285: #  define EXEC(XT)	({cfa=(XT); goto **cfa;})
  286: #endif
  287: 
  288: #if THREADING_SCHEME==2
  289: #warning indirect threading scheme 2: autoinc, long latency
  290: #  define CFA_NEXT
  291: #  define NEXT_P0	({cfa=*ip++;})
  292: #  define IP		(ip-1)
  293: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  294: #  define NEXT_INST	(cfa)
  295: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  296: #  define DEF_CA	Label ca;
  297: #  define NEXT_P1	({ca=*cfa;})
  298: #  define NEXT_P2	({goto *ca;})
  299: #  define EXEC(XT)	({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
  300: #endif
  301: 
  302: 
  303: #if THREADING_SCHEME==3
  304: #warning indirect threading scheme 3: autoinc, low latency, cisc
  305: #  define CFA_NEXT
  306: #  define NEXT_P0
  307: #  define IP		(ip)
  308: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  309: #  define NEXT_INST	(*ip)
  310: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  311: #  define DEF_CA
  312: #  define NEXT_P1
  313: #  define NEXT_P2	({cfa=*ip++; goto **cfa;})
  314: #  define EXEC(XT)	({cfa=(XT); goto **cfa;})
  315: #endif
  316: 
  317: #if THREADING_SCHEME==4
  318: #warning indirect threading scheme 4: autoinc, low latency
  319: #  define CFA_NEXT
  320: #  define NEXT_P0	({cfa=*ip++;})
  321: #  define IP		(ip-1)
  322: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  323: #  define NEXT_INST	(cfa)
  324: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  325: #  define DEF_CA	Label ca;
  326: #  define NEXT_P1	({ca=*cfa;})
  327: #  define NEXT_P2	({goto *ca;})
  328: #  define EXEC(XT)	({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
  329: #endif
  330: 
  331: 
  332: #if THREADING_SCHEME==5
  333: #warning indirect threading scheme 5: long latency, cisc
  334: #  define CFA_NEXT
  335: #  define NEXT_P0	({cfa=*ip;})
  336: #  define IP		(ip)
  337: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  338: #  define NEXT_INST	(cfa)
  339: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  340: #  define DEF_CA
  341: #  define NEXT_P1	(ip++)
  342: #  define NEXT_P2	({goto **cfa;})
  343: #  define EXEC(XT)	({cfa=(XT); goto **cfa;})
  344: #endif
  345: 
  346: #if THREADING_SCHEME==6
  347: #warning indirect threading scheme 6: long latency
  348: #  define CFA_NEXT
  349: #  define NEXT_P0	({cfa=*ip;})
  350: #  define IP		(ip)
  351: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  352: #  define NEXT_INST	(cfa)
  353: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  354: #  define DEF_CA	Label ca;
  355: #  define NEXT_P1	({ip++; ca=*cfa;})
  356: #  define NEXT_P2	({goto *ca;})
  357: #  define EXEC(XT)	({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
  358: #endif
  359: 
  360: #if THREADING_SCHEME==7
  361: #warning indirect threading scheme 7: low latency
  362: #  define CFA_NEXT
  363: #  define NEXT_P0	({cfa=*ip;})
  364: #  define IP		(ip)
  365: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  366: #  define NEXT_INST	(cfa)
  367: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  368: #  define DEF_CA	Label ca;
  369: #  define NEXT_P1	({ip++; ca=*cfa;})
  370: #  define NEXT_P2	({goto *ca;})
  371: #  define EXEC(XT)	({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
  372: #endif
  373: 
  374: #if THREADING_SCHEME==8
  375: #warning indirect threading scheme 8: low latency,cisc
  376: #  define CFA_NEXT
  377: #  define NEXT_P0
  378: #  define IP		(ip)
  379: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  380: #  define NEXT_INST	(*ip)
  381: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  382: #  define DEF_CA
  383: #  define NEXT_P1
  384: #  define NEXT_P2	({cfa=*ip++; goto **cfa;})
  385: #  define EXEC(XT)	({cfa=(XT); goto **cfa;})
  386: #endif
  387: 
  388: /* indirect threaded */
  389: #endif
  390: 
  391: #endif /* !defined(DOUBLY_INDIRECT) */
  392: 
  393: #define NEXT ({DEF_CA NEXT_P1; NEXT_P2;})
  394: 

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