File:  [gforth] / gforth / engine / threaded.h
Revision 1.9: download - view: text, annotated - select for diffs
Sun Dec 24 15:54:18 2000 UTC (19 years, 10 months ago) by anton
Branches: MAIN
CVS tags: HEAD
finishing touches to dealing with inst-stream in prims2x.fs
converted prims to using this new feature for inline arguments (prefix '#')
commented out prim* targets in engine/Makefile.in (out-of-date)

    1: /* This file defines a number of threading schemes.
    2: 
    3:   Copyright (C) 1995, 1996,1997,1999 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., 59 Temple Place, Suite 330, Boston, MA 02111, 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: if NEXT uses cfa, you have to #define CFA_NEXT, to get
   95:  * cfa declared in engine.
   96:  */
   97: 
   98: #ifdef DOUBLY_INDIRECT
   99: #  define CFA_NEXT
  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 CFA_NEXT
  121: #  define NEXT_P0	({cfa=*ip++;})
  122: #  define IP		(ip-1)
  123: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  124: #  define NEXT_INST	(cfa)
  125: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  126: #  define DEF_CA
  127: #  define NEXT_P1
  128: #  define NEXT_P2	({goto *cfa;})
  129: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  130: #endif
  131: 
  132: #if THREADING_SCHEME==2
  133: #warning direct threading scheme 2: autoinc, long latency, cfa dead
  134: #ifndef GETCFA
  135: #error GETCFA must be defined for cfa dead threading
  136: #endif
  137: #  define NEXT_P0	(ip++)
  138: #  define IP		(ip-1)
  139: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  140: #  define NEXT_INST	(*(ip-1))
  141: #  define INC_IP(const_inc)	({ ip+=(const_inc);})
  142: #  define DEF_CA
  143: #  define NEXT_P1
  144: #  define NEXT_P2	({goto **(ip-1);})
  145: #  define EXEC(XT)	({goto *(XT);})
  146: #endif
  147: 
  148: 
  149: #if THREADING_SCHEME==3
  150: #warning direct threading scheme 3: autoinc, low latency, cfa live
  151: #  define CFA_NEXT
  152: #  define NEXT_P0
  153: #  define IP		(ip)
  154: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  155: #  define NEXT_INST	(*ip)
  156: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  157: #  define DEF_CA
  158: #  define NEXT_P1	({cfa=*ip++;})
  159: #  define NEXT_P2	({goto *cfa;})
  160: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  161: #endif
  162: 
  163: #if THREADING_SCHEME==4
  164: #warning direct threading scheme 4: autoinc, low latency, cfa dead
  165: #ifndef GETCFA
  166: #error GETCFA must be defined for cfa dead threading
  167: #endif
  168: #  define NEXT_P0
  169: #  define IP		(ip)
  170: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  171: #  define NEXT_INST	(*ip)
  172: #  define INC_IP(const_inc)	({ ip+=(const_inc);})
  173: #  define DEF_CA
  174: #  define NEXT_P1
  175: #  define NEXT_P2	({goto **(ip++);})
  176: #  define EXEC(XT)	({goto *(XT);})
  177: #endif
  178: 
  179: #if THREADING_SCHEME==5
  180: #warning direct threading scheme 5: long latency, cfa live
  181: #  define CFA_NEXT
  182: #  define NEXT_P0	({cfa=*ip;})
  183: #  define IP		(ip)
  184: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  185: #  define NEXT_INST	(cfa)
  186: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  187: #  define DEF_CA
  188: #  define NEXT_P1	(ip++)
  189: #  define NEXT_P2	({goto *cfa;})
  190: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  191: #endif
  192: 
  193: #if THREADING_SCHEME==6
  194: #warning direct threading scheme 6: long latency, cfa dead
  195: #ifndef GETCFA
  196: #error GETCFA must be defined for cfa dead threading
  197: #endif
  198: #  define NEXT_P0
  199: #  define IP		(ip)
  200: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  201: #  define NEXT_INST	(*ip)
  202: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  203: #  define DEF_CA
  204: #  define NEXT_P1	(ip++)
  205: #  define NEXT_P2	({goto **(ip-1);})
  206: #  define EXEC(XT)	({goto *(XT);})
  207: #endif
  208: 
  209: 
  210: #if THREADING_SCHEME==7
  211: #warning direct threading scheme 7: low latency, cfa live
  212: #  define CFA_NEXT
  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	({cfa=*ip++;})
  220: #  define NEXT_P2	({goto *cfa;})
  221: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  222: #endif
  223: 
  224: #if THREADING_SCHEME==8
  225: #warning direct threading scheme 8: cfa dead, i386 hack
  226: #ifndef GETCFA
  227: #error GETCFA must be defined for cfa dead threading
  228: #endif
  229: #  define NEXT_P0
  230: #  define IP		(ip)
  231: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  232: #  define NEXT_INST	(*IP)
  233: #  define INC_IP(const_inc)	({ ip+=(const_inc);})
  234: #  define DEF_CA
  235: #  define NEXT_P1	(ip++)
  236: #  define NEXT_P2	({goto **(ip-1);})
  237: #  define EXEC(XT)	({goto *(XT);})
  238: #endif
  239: 
  240: #if THREADING_SCHEME==9
  241: #warning direct threading scheme 9: Power/PPC hack, long latency
  242: /* Power uses a prepare-to-branch instruction, and the latency between
  243:    this inst and the branch is 5 cycles on a PPC604; so we utilize this
  244:    to do some prefetching in between */
  245: #  define CFA_NEXT
  246: #  define NEXT_P0
  247: #  define IP		ip
  248: #  define SET_IP(p)	({ip=(p); next_cfa=*ip; NEXT_P0;})
  249: #  define NEXT_INST	(next_cfa)
  250: #  define INC_IP(const_inc)	({next_cfa=IP[const_inc]; ip+=(const_inc);})
  251: #  define DEF_CA	
  252: #  define NEXT_P1	({cfa=next_cfa; ip++; next_cfa=*ip;})
  253: #  define NEXT_P2	({goto *cfa;})
  254: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  255: #  define MORE_VARS	Xt next_cfa;
  256: #endif
  257: 
  258: #if THREADING_SCHEME==10
  259: #warning direct threading scheme 10: plain (no attempt at scheduling)
  260: #  define CFA_NEXT
  261: #  define NEXT_P0
  262: #  define IP		(ip)
  263: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  264: #  define NEXT_INST	(*ip)
  265: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  266: #  define DEF_CA
  267: #  define NEXT_P1
  268: #  define NEXT_P2	({cfa=*ip++; goto *cfa;})
  269: #  define EXEC(XT)	({cfa=(XT); goto *cfa;})
  270: #endif
  271: 
  272: /* direct threaded */
  273: #else
  274: /* indirect THREADED  */
  275: 
  276: #if THREADING_SCHEME==1
  277: #warning indirect threading scheme 1: autoinc, long latency, cisc
  278: #  define CFA_NEXT
  279: #  define NEXT_P0	({cfa=*ip++;})
  280: #  define IP		(ip-1)
  281: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  282: #  define NEXT_INST	(cfa)
  283: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  284: #  define DEF_CA
  285: #  define NEXT_P1
  286: #  define NEXT_P2	({goto **cfa;})
  287: #  define EXEC(XT)	({cfa=(XT); goto **cfa;})
  288: #endif
  289: 
  290: #if THREADING_SCHEME==2
  291: #warning indirect threading scheme 2: autoinc, long latency
  292: #  define CFA_NEXT
  293: #  define NEXT_P0	({cfa=*ip++;})
  294: #  define IP		(ip-1)
  295: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  296: #  define NEXT_INST	(cfa)
  297: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  298: #  define DEF_CA	Label ca;
  299: #  define NEXT_P1	({ca=*cfa;})
  300: #  define NEXT_P2	({goto *ca;})
  301: #  define EXEC(XT)	({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
  302: #endif
  303: 
  304: 
  305: #if THREADING_SCHEME==3
  306: #warning indirect threading scheme 3: autoinc, low latency, cisc
  307: #  define CFA_NEXT
  308: #  define NEXT_P0
  309: #  define IP		(ip)
  310: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  311: #  define NEXT_INST	(*ip)
  312: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  313: #  define DEF_CA
  314: #  define NEXT_P1
  315: #  define NEXT_P2	({cfa=*ip++; goto **cfa;})
  316: #  define EXEC(XT)	({cfa=(XT); goto **cfa;})
  317: #endif
  318: 
  319: #if THREADING_SCHEME==4
  320: #warning indirect threading scheme 4: autoinc, low latency
  321: #  define CFA_NEXT
  322: #  define NEXT_P0	({cfa=*ip++;})
  323: #  define IP		(ip-1)
  324: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  325: #  define NEXT_INST	(cfa)
  326: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  327: #  define DEF_CA	Label ca;
  328: #  define NEXT_P1	({ca=*cfa;})
  329: #  define NEXT_P2	({goto *ca;})
  330: #  define EXEC(XT)	({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
  331: #endif
  332: 
  333: 
  334: #if THREADING_SCHEME==5
  335: #warning indirect threading scheme 5: long latency, cisc
  336: #  define CFA_NEXT
  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
  343: #  define NEXT_P1	(ip++)
  344: #  define NEXT_P2	({goto **cfa;})
  345: #  define EXEC(XT)	({cfa=(XT); goto **cfa;})
  346: #endif
  347: 
  348: #if THREADING_SCHEME==6
  349: #warning indirect threading scheme 6: long latency
  350: #  define CFA_NEXT
  351: #  define NEXT_P0	({cfa=*ip;})
  352: #  define IP		(ip)
  353: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  354: #  define NEXT_INST	(cfa)
  355: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  356: #  define DEF_CA	Label ca;
  357: #  define NEXT_P1	({ip++; ca=*cfa;})
  358: #  define NEXT_P2	({goto *ca;})
  359: #  define EXEC(XT)	({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
  360: #endif
  361: 
  362: #if THREADING_SCHEME==7
  363: #warning indirect threading scheme 7: low latency
  364: #  define CFA_NEXT
  365: #  define NEXT_P0	({cfa=*ip;})
  366: #  define IP		(ip)
  367: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  368: #  define NEXT_INST	(cfa)
  369: #  define INC_IP(const_inc)	({cfa=IP[const_inc]; ip+=(const_inc);})
  370: #  define DEF_CA	Label ca;
  371: #  define NEXT_P1	({ip++; ca=*cfa;})
  372: #  define NEXT_P2	({goto *ca;})
  373: #  define EXEC(XT)	({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
  374: #endif
  375: 
  376: #if THREADING_SCHEME==8
  377: #warning indirect threading scheme 8: low latency,cisc
  378: #  define CFA_NEXT
  379: #  define NEXT_P0
  380: #  define IP		(ip)
  381: #  define SET_IP(p)	({ip=(p); NEXT_P0;})
  382: #  define NEXT_INST	(*ip)
  383: #  define INC_IP(const_inc)	({ip+=(const_inc);})
  384: #  define DEF_CA
  385: #  define NEXT_P1
  386: #  define NEXT_P2	({cfa=*ip++; goto **cfa;})
  387: #  define EXEC(XT)	({cfa=(XT); goto **cfa;})
  388: #endif
  389: 
  390: /* indirect threaded */
  391: #endif
  392: 
  393: #endif /* !defined(DOUBLY_INDIRECT) */
  394: 
  395: #define NEXT ({DEF_CA NEXT_P1; NEXT_P2;})
  396: #define ipTOS NEXT_INST

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