File:  [gforth] / gforth / engine / threaded.h
Revision 1.26: download - view: text, annotated - select for diffs
Sat Jun 19 14:19:44 2004 UTC (16 years, 4 months ago) by pazsan
Branches: MAIN
CVS tags: HEAD
Changed empty expressions to do { exp } while(0)

    1: /* This file defines a number of threading schemes.
    2: 
    3:   Copyright (C) 1995, 1996,1997,1999,2003 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: #ifdef DOUBLY_INDIRECT
   95: # ifndef DEBUG_DITC
   96: #  define DEBUG_DITC 0
   97: # endif
   98: /* define to 1 if you want to check consistency */
   99: #  define NEXT_P0	do {cfa1=cfa; cfa=*ip;} while(0)
  100: #  define CFA		cfa1
  101: #  define MORE_VARS     Xt cfa1;
  102: #  define IP		(ip)
  103: #  define SET_IP(p)	do {ip=(p); cfa=*ip;} while(0)
  104: #  define NEXT_INST	(cfa)
  105: #  define INC_IP(const_inc)	do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
  106: #  define DEF_CA	Label ca;
  107: #  define NEXT_P1	do {\
  108:   if (DEBUG_DITC && (cfa<=vm_prims+DOESJUMP || cfa>=vm_prims+npriminfos)) \
  109:     fprintf(stderr,"NEXT encountered prim %p at ip=%p\n", cfa, ip); \
  110:   ip++;} while(0)
  111: #  define NEXT_P2	do {ca=**cfa; goto *ca;} while(0)
  112: #  define EXEC(XT)	do {DEF_CA cfa=(XT);\
  113:   if (DEBUG_DITC && (cfa>vm_prims+DOESJUMP && cfa<vm_prims+npriminfos)) \
  114:     fprintf(stderr,"EXEC encountered xt %p at ip=%p, vm_prims=%p, xts=%p\n", cfa, ip, vm_prims, xts); \
  115:  ca=**cfa; goto *ca;} while(0)
  116: 
  117: #elif defined(NO_IP)
  118: 
  119: #define NEXT_P0
  120: #  define CFA		cfa
  121: #define SET_IP(target)	assert(0)
  122: #define INC_IP(n)	((void)0)
  123: #define DEF_CA
  124: #define NEXT_P1
  125: #define NEXT_P2		do {goto *next_code;} while(0)
  126: /* set next_code to the return address before performing EXEC */
  127: #define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  128: 
  129: #else  /* !defined(DOUBLY_INDIRECT) && !defined(NO_IP) */
  130: 
  131: #if defined(DIRECT_THREADED)
  132: 
  133: /* This lets the compiler know that cfa is dead before; we place it at
  134:    "goto *"s that perform direct threaded dispatch (i.e., not EXECUTE
  135:    etc.), and thus do not reach doers, which would use cfa; the only
  136:    way to a doer is through EXECUTE etc., which set the cfa
  137:    themselves.
  138: 
  139:    Some of these direct threaded schemes use "cfa" to hold the code
  140:    address in normal direct threaded code.  Of course we cannot use
  141:    KILLS there.
  142: 
  143:    KILLS works by having an empty asm instruction, and claiming to the
  144:    compiler that it writes to cfa.
  145: 
  146:    KILLS is optional.  You can write
  147: 
  148: #define KILLS
  149: 
  150:    and lose just a little performance.
  151: */
  152: #define KILLS asm("":"=X"(cfa));
  153: 
  154: #ifndef THREADING_SCHEME
  155: #define THREADING_SCHEME 7
  156: #endif
  157: 
  158: #if THREADING_SCHEME==1
  159: #warning direct threading scheme 1: autoinc, long latency, cfa live
  160: #  define NEXT_P0	do {cfa1=cfa; cfa=*ip++;} while(0)
  161: #  define CFA		cfa1
  162: #  define MORE_VARS     Xt cfa1;
  163: #  define IP		(ip-1)
  164: #  define SET_IP(p)	do {ip=(p); cfa=*ip++;} while(0)
  165: #  define NEXT_INST	(cfa)
  166: #  define INC_IP(const_inc)	do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
  167: #  define DEF_CA
  168: #  define NEXT_P1
  169: #  define NEXT_P2	do {goto *cfa;} while(0)
  170: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  171: #endif
  172: 
  173: #if THREADING_SCHEME==2
  174: #warning direct threading scheme 2: autoinc, long latency, cfa dead
  175: #  define NEXT_P0	(ip++)
  176: #  define CFA		cfa
  177: #  define IP		(ip-1)
  178: #  define SET_IP(p)	do {ip=(p); NEXT_P0;} while(0)
  179: #  define NEXT_INST	(*(ip-1))
  180: #  define INC_IP(const_inc)	do { ip+=(const_inc);} while(0)
  181: #  define DEF_CA
  182: #  define NEXT_P1
  183: #  define NEXT_P2	do {KILLS goto **(ip-1);} while(0)
  184: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  185: #endif
  186: 
  187: 
  188: #if THREADING_SCHEME==3
  189: #warning direct threading scheme 3: autoinc, low latency, cfa live
  190: #  define NEXT_P0
  191: #  define CFA		cfa
  192: #  define IP		(ip)
  193: #  define SET_IP(p)	do {ip=(p); NEXT_P0;} while(0)
  194: #  define NEXT_INST	(*ip)
  195: #  define INC_IP(const_inc)	do {ip+=(const_inc);} while(0)
  196: #  define DEF_CA
  197: #  define NEXT_P1	do {cfa=*ip++;} while(0)
  198: #  define NEXT_P2	do {goto *cfa;} while(0)
  199: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  200: #endif
  201: 
  202: #if THREADING_SCHEME==4
  203: #warning direct threading scheme 4: autoinc, low latency, cfa dead
  204: #  define NEXT_P0
  205: #  define CFA		cfa
  206: #  define IP		(ip)
  207: #  define SET_IP(p)	do {ip=(p); NEXT_P0;} while(0)
  208: #  define NEXT_INST	(*ip)
  209: #  define INC_IP(const_inc)	do { ip+=(const_inc);} while(0)
  210: #  define DEF_CA
  211: #  define NEXT_P1
  212: #  define NEXT_P2	do {KILLS goto **(ip++);} while(0)
  213: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  214: #endif
  215: 
  216: #if THREADING_SCHEME==5
  217: #warning direct threading scheme 5: long latency, cfa live
  218: #  define NEXT_P0	do {cfa1=cfa; cfa=*ip;} while(0)
  219: #  define CFA		cfa1
  220: #  define MORE_VARS     Xt cfa1;
  221: #  define IP		(ip)
  222: #  define SET_IP(p)	do {ip=(p); cfa=*ip;} while(0)
  223: #  define NEXT_INST	(cfa)
  224: #  define INC_IP(const_inc)	do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
  225: #  define DEF_CA
  226: #  define NEXT_P1	(ip++)
  227: #  define NEXT_P2	do {goto *cfa;} while(0)
  228: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  229: #endif
  230: 
  231: #if THREADING_SCHEME==6
  232: #warning direct threading scheme 6: long latency, cfa dead
  233: #  define NEXT_P0
  234: #  define CFA		cfa
  235: #  define IP		(ip)
  236: #  define SET_IP(p)	do {ip=(p); NEXT_P0;} while(0)
  237: #  define NEXT_INST	(*ip)
  238: #  define INC_IP(const_inc)	do {ip+=(const_inc);} while(0)
  239: #  define DEF_CA
  240: #  define NEXT_P1	(ip++)
  241: #  define NEXT_P2	do {KILLS goto **(ip-1);} while(0)
  242: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  243: #endif
  244: 
  245: 
  246: #if THREADING_SCHEME==7
  247: #warning direct threading scheme 7: low latency, cfa live
  248: #  define NEXT_P0
  249: #  define CFA		cfa
  250: #  define IP		(ip)
  251: #  define SET_IP(p)	do {ip=(p); NEXT_P0;} while(0)
  252: #  define NEXT_INST	(*ip)
  253: #  define INC_IP(const_inc)	do {ip+=(const_inc);} while(0)
  254: #  define DEF_CA
  255: #  define NEXT_P1	do {cfa=*ip++;} while(0)
  256: #  define NEXT_P2	do {goto *cfa;} while(0)
  257: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  258: #endif
  259: 
  260: #if THREADING_SCHEME==8
  261: #warning direct threading scheme 8: cfa dead, i386 hack
  262: #  define NEXT_P0
  263: #  define CFA		cfa
  264: #  define IP		(ip)
  265: #  define SET_IP(p)	do {ip=(p); NEXT_P0;} while(0)
  266: #  define NEXT_INST	(*IP)
  267: #  define INC_IP(const_inc)	do { ip+=(const_inc);} while(0)
  268: #  define DEF_CA
  269: #  define NEXT_P1	(ip++)
  270: #  define NEXT_P2	do {KILLS goto **(ip-1);} while(0)
  271: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  272: #endif
  273: 
  274: #if THREADING_SCHEME==9
  275: #warning direct threading scheme 9: Power/PPC hack, long latency
  276: /* Power uses a prepare-to-branch instruction, and the latency between
  277:    this inst and the branch is 5 cycles on a PPC604; so we utilize this
  278:    to do some prefetching in between */
  279: #  define NEXT_P0
  280: #  define CFA		cfa
  281: #  define IP		ip
  282: #  define SET_IP(p)	do {ip=(p); next_cfa=*ip; NEXT_P0;} while(0)
  283: #  define NEXT_INST	(next_cfa)
  284: #  define INC_IP(const_inc)	do {next_cfa=IP[const_inc]; ip+=(const_inc);} while(0)
  285: #  define DEF_CA	
  286: #  define NEXT_P1	do {cfa=next_cfa; ip++; next_cfa=*ip;} while(0)
  287: #  define NEXT_P2	do {goto *cfa;} while(0)
  288: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  289: #  define MORE_VARS	Xt next_cfa;
  290: #endif
  291: 
  292: #if THREADING_SCHEME==10
  293: #warning direct threading scheme 10: plain (no attempt at scheduling)
  294: #  define NEXT_P0
  295: #  define CFA		cfa
  296: #  define IP		(ip)
  297: #  define SET_IP(p)	do {ip=(p); NEXT_P0;} while(0)
  298: #  define NEXT_INST	(*ip)
  299: #  define INC_IP(const_inc)	do {ip+=(const_inc);} while(0)
  300: #  define DEF_CA
  301: #  define NEXT_P1
  302: #  define NEXT_P2	do {cfa=*ip++; goto *cfa;} while(0)
  303: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  304: #endif
  305: 
  306: /* direct threaded */
  307: #else
  308: /* indirect THREADED  */
  309: 
  310: #ifndef THREADING_SCHEME
  311: #define THREADING_SCHEME 6
  312: #endif
  313: 
  314: #if THREADING_SCHEME==1
  315: #warning indirect threading scheme 1: autoinc, long latency, cisc
  316: #  define NEXT_P0	do {cfa1=cfa; cfa=*ip++;} while(0)
  317: #  define CFA		cfa1
  318: #  define MORE_VARS     Xt cfa1;
  319: #  define IP		(ip-1)
  320: #  define SET_IP(p)	do {ip=(p); cfa=*ip++;} while(0)
  321: #  define NEXT_INST	(cfa)
  322: #  define INC_IP(const_inc)	do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
  323: #  define DEF_CA
  324: #  define NEXT_P1
  325: #  define NEXT_P2	do {goto **cfa;} while(0)
  326: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  327: #endif
  328: 
  329: #if THREADING_SCHEME==2
  330: #warning indirect threading scheme 2: autoinc, long latency
  331: #  define NEXT_P0	do {cfa1=cfa; cfa=*ip++;} while(0)
  332: #  define CFA		cfa1
  333: #  define MORE_VARS     Xt cfa1;
  334: #  define IP		(ip-1)
  335: #  define SET_IP(p)	do {ip=(p); cfa=*ip++;} while(0)
  336: #  define NEXT_INST	(cfa)
  337: #  define INC_IP(const_inc)	do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
  338: #  define DEF_CA	Label ca;
  339: #  define NEXT_P1	do {ca=*cfa;} while(0)
  340: #  define NEXT_P2	do {goto *ca;} while(0)
  341: #  define EXEC(XT)	do {DEF_CA cfa=(XT); ca=*cfa; goto *ca;} while(0)
  342: #endif
  343: 
  344: 
  345: #if THREADING_SCHEME==3
  346: #warning indirect threading scheme 3: autoinc, low latency, cisc
  347: #  define NEXT_P0
  348: #  define CFA		cfa
  349: #  define IP		(ip)
  350: #  define SET_IP(p)	do {ip=(p); NEXT_P0;} while(0)
  351: #  define NEXT_INST	(*ip)
  352: #  define INC_IP(const_inc)	do {ip+=(const_inc);} while(0)
  353: #  define DEF_CA
  354: #  define NEXT_P1
  355: #  define NEXT_P2	do {cfa=*ip++; goto **cfa;} while(0)
  356: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  357: #endif
  358: 
  359: #if THREADING_SCHEME==4
  360: #warning indirect threading scheme 4: autoinc, low latency
  361: #  define NEXT_P0	do {cfa1=cfa; cfa=*ip++;} while(0)
  362: #  define CFA		cfa1
  363: #  define MORE_VARS     Xt cfa1;
  364: #  define IP		(ip-1)
  365: #  define SET_IP(p)	do {ip=(p); cfa=*ip++;} while(0)
  366: #  define NEXT_INST	(cfa)
  367: #  define INC_IP(const_inc)	do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
  368: #  define DEF_CA	Label ca;
  369: #  define NEXT_P1	do {ca=*cfa;} while(0)
  370: #  define NEXT_P2	do {goto *ca;} while(0)
  371: #  define EXEC(XT)	do {DEF_CA cfa=(XT); ca=*cfa; goto *ca;} while(0)
  372: #endif
  373: 
  374: 
  375: #if THREADING_SCHEME==5
  376: #warning indirect threading scheme 5: long latency, cisc
  377: #  define NEXT_P0	do {cfa1=cfa; cfa=*ip;} while(0)
  378: #  define CFA		cfa1
  379: #  define MORE_VARS     Xt cfa1;
  380: #  define IP		(ip)
  381: #  define SET_IP(p)	do {ip=(p); cfa=*ip;} while(0)
  382: #  define NEXT_INST	(cfa)
  383: #  define INC_IP(const_inc)	do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
  384: #  define DEF_CA
  385: #  define NEXT_P1	(ip++)
  386: #  define NEXT_P2	do {goto **cfa;} while(0)
  387: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  388: #endif
  389: 
  390: #if THREADING_SCHEME==6
  391: #warning indirect threading scheme 6: long latency
  392: #  define NEXT_P0	do {cfa1=cfa; cfa=*ip;} while(0)
  393: #  define CFA		cfa1
  394: #  define MORE_VARS     Xt cfa1;
  395: #  define IP		(ip)
  396: #  define SET_IP(p)	do {ip=(p); cfa=*ip;} while(0)
  397: #  define NEXT_INST	(cfa)
  398: #  define INC_IP(const_inc)	do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
  399: #  define DEF_CA	Label ca;
  400: #  define NEXT_P1	do {ip++; ca=*cfa;} while(0)
  401: #  define NEXT_P2	do {goto *ca;} while(0)
  402: #  define EXEC(XT)	do {DEF_CA cfa=(XT); ca=*cfa; goto *ca;} while(0)
  403: #endif
  404: 
  405: #if THREADING_SCHEME==7
  406: #warning indirect threading scheme 7: low latency
  407: #  define NEXT_P0	do {cfa1=cfa; cfa=*ip;} while(0)
  408: #  define CFA		cfa1
  409: #  define MORE_VARS     Xt cfa1;
  410: #  define IP		(ip)
  411: #  define SET_IP(p)	do {ip=(p); cfa=*ip;} while(0)
  412: #  define NEXT_INST	(cfa)
  413: #  define INC_IP(const_inc)	do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
  414: #  define DEF_CA	Label ca;
  415: #  define NEXT_P1	do {ip++; ca=*cfa;} while(0)
  416: #  define NEXT_P2	do {goto *ca;} while(0)
  417: #  define EXEC(XT)	do {DEF_CA cfa=(XT); ca=*cfa; goto *ca;} while(0)
  418: #endif
  419: 
  420: #if THREADING_SCHEME==8
  421: #warning indirect threading scheme 8: low latency,cisc
  422: #  define NEXT_P0
  423: #  define CFA		cfa
  424: #  define IP		(ip)
  425: #  define SET_IP(p)	do {ip=(p); NEXT_P0;} while(0)
  426: #  define NEXT_INST	(*ip)
  427: #  define INC_IP(const_inc)	do {ip+=(const_inc);} while(0)
  428: #  define DEF_CA
  429: #  define NEXT_P1
  430: #  define NEXT_P2	do {cfa=*ip++; goto **cfa;} while(0)
  431: #  define EXEC(XT)	do {cfa=(XT); goto **cfa;} while(0)
  432: #endif
  433: 
  434: /* indirect threaded */
  435: #endif
  436: 
  437: #endif /* !defined(DOUBLY_INDIRECT) && !defined(NO_IP) */
  438: 
  439: #define NEXT do {DEF_CA NEXT_P1; NEXT_P2;} while(0)
  440: #define IPTOS NEXT_INST

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