Annotation of gforth/engine/threaded.h, revision 1.16
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:
1.16 ! anton 94:
! 95:
1.1 anton 96: #ifdef DOUBLY_INDIRECT
97: # define NEXT_P0 ({cfa=*ip;})
98: # define IP (ip)
1.3 anton 99: # define SET_IP(p) ({ip=(p); NEXT_P0;})
1.1 anton 100: # define NEXT_INST (cfa)
101: # define INC_IP(const_inc) ({cfa=IP[const_inc]; ip+=(const_inc);})
102: # define DEF_CA Label ca;
1.13 anton 103: # define NEXT_P1 ({\
1.14 anton 104: if (cfa<=vm_prims+DOESJUMP || cfa>=vm_prims+npriminfos) \
1.13 anton 105: fprintf(stderr,"NEXT encountered prim %p at ip=%p\n", cfa, ip); \
106: ip++; ca=**cfa;})
1.1 anton 107: # define NEXT_P2 ({goto *ca;})
1.13 anton 108: # define EXEC(XT) ({DEF_CA cfa=(XT);\
1.14 anton 109: if (cfa>vm_prims+DOESJUMP && cfa<vm_prims+npriminfos) \
110: fprintf(stderr,"EXEC encountered xt %p at ip=%p, vm_prims=%p, xts=%p\n", cfa, ip, vm_prims, xts); \
1.13 anton 111: ca=**cfa; goto *ca;})
1.1 anton 112:
1.16 ! anton 113: #elif defined(NO_IP)
! 114:
! 115: #define NEXT_P0
! 116: #define SET_IP(target) assert(0)
! 117: #define INC_IP(n) ((void)0)
! 118: #define DEF_CA
! 119: #define NEXT_P1
! 120: #define NEXT_P2 ({goto *next_code;})
! 121: /* set next_code to the return address before performing EXEC */
! 122: #define EXEC(XT) ({cfa=(XT); goto **cfa;})
! 123:
! 124: #else /* !defined(DOUBLY_INDIRECT) && !defined(NO_IP) */
1.1 anton 125:
1.3 anton 126: #if defined(DIRECT_THREADED)
127:
128: #if THREADING_SCHEME==1
129: #warning direct threading scheme 1: autoinc, long latency, cfa live
1.1 anton 130: # define NEXT_P0 ({cfa=*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 (cfa)
134: # define INC_IP(const_inc) ({cfa=IP[const_inc]; ip+=(const_inc);})
135: # define DEF_CA
136: # define NEXT_P1
137: # define NEXT_P2 ({goto *cfa;})
1.15 anton 138: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
1.1 anton 139: #endif
140:
1.3 anton 141: #if THREADING_SCHEME==2
142: #warning direct threading scheme 2: autoinc, long latency, cfa dead
1.1 anton 143: # define NEXT_P0 (ip++)
144: # define IP (ip-1)
1.3 anton 145: # define SET_IP(p) ({ip=(p); NEXT_P0;})
1.1 anton 146: # define NEXT_INST (*(ip-1))
147: # define INC_IP(const_inc) ({ ip+=(const_inc);})
148: # define DEF_CA
149: # define NEXT_P1
150: # define NEXT_P2 ({goto **(ip-1);})
1.15 anton 151: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
1.1 anton 152: #endif
153:
154:
1.3 anton 155: #if THREADING_SCHEME==3
156: #warning direct threading scheme 3: autoinc, low latency, cfa live
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 ({cfa=*ip++;})
164: # define NEXT_P2 ({goto *cfa;})
1.15 anton 165: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
1.1 anton 166: #endif
167:
1.3 anton 168: #if THREADING_SCHEME==4
169: #warning direct threading scheme 4: autoinc, low latency, cfa dead
1.1 anton 170: # define NEXT_P0
171: # define IP (ip)
1.3 anton 172: # define SET_IP(p) ({ip=(p); NEXT_P0;})
1.1 anton 173: # define NEXT_INST (*ip)
174: # define INC_IP(const_inc) ({ ip+=(const_inc);})
175: # define DEF_CA
176: # define NEXT_P1
177: # define NEXT_P2 ({goto **(ip++);})
1.15 anton 178: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
1.1 anton 179: #endif
180:
1.3 anton 181: #if THREADING_SCHEME==5
182: #warning direct threading scheme 5: long latency, cfa live
1.1 anton 183: # define NEXT_P0 ({cfa=*ip;})
184: # define IP (ip)
1.3 anton 185: # define SET_IP(p) ({ip=(p); NEXT_P0;})
1.1 anton 186: # define NEXT_INST (cfa)
187: # define INC_IP(const_inc) ({cfa=IP[const_inc]; ip+=(const_inc);})
188: # define DEF_CA
189: # define NEXT_P1 (ip++)
190: # define NEXT_P2 ({goto *cfa;})
1.15 anton 191: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
1.1 anton 192: #endif
193:
1.3 anton 194: #if THREADING_SCHEME==6
195: #warning direct threading scheme 6: long latency, cfa dead
1.1 anton 196: # define NEXT_P0
197: # define IP (ip)
1.3 anton 198: # define SET_IP(p) ({ip=(p); NEXT_P0;})
1.1 anton 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);})
1.15 anton 204: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
1.1 anton 205: #endif
206:
207:
1.3 anton 208: #if THREADING_SCHEME==7
209: #warning direct threading scheme 7: low latency, cfa live
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 ({cfa=*ip++;})
217: # define NEXT_P2 ({goto *cfa;})
1.15 anton 218: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
1.1 anton 219: #endif
220:
1.3 anton 221: #if THREADING_SCHEME==8
222: #warning direct threading scheme 8: cfa dead, i386 hack
1.1 anton 223: # define NEXT_P0
224: # define IP (ip)
1.3 anton 225: # define SET_IP(p) ({ip=(p); NEXT_P0;})
1.1 anton 226: # define NEXT_INST (*IP)
227: # define INC_IP(const_inc) ({ ip+=(const_inc);})
228: # define DEF_CA
229: # define NEXT_P1 (ip++)
230: # define NEXT_P2 ({goto **(ip-1);})
1.15 anton 231: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
1.1 anton 232: #endif
233:
1.3 anton 234: #if THREADING_SCHEME==9
235: #warning direct threading scheme 9: Power/PPC hack, long latency
236: /* Power uses a prepare-to-branch instruction, and the latency between
237: this inst and the branch is 5 cycles on a PPC604; so we utilize this
238: to do some prefetching in between */
239: # define NEXT_P0
240: # define IP ip
241: # define SET_IP(p) ({ip=(p); next_cfa=*ip; NEXT_P0;})
242: # define NEXT_INST (next_cfa)
243: # define INC_IP(const_inc) ({next_cfa=IP[const_inc]; ip+=(const_inc);})
1.8 anton 244: # define DEF_CA
245: # define NEXT_P1 ({cfa=next_cfa; ip++; next_cfa=*ip;})
246: # define NEXT_P2 ({goto *cfa;})
1.15 anton 247: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
1.3 anton 248: # define MORE_VARS Xt next_cfa;
249: #endif
1.1 anton 250:
1.3 anton 251: #if THREADING_SCHEME==10
252: #warning direct threading scheme 10: plain (no attempt at scheduling)
253: # define NEXT_P0
254: # define IP (ip)
255: # define SET_IP(p) ({ip=(p); NEXT_P0;})
256: # define NEXT_INST (*ip)
257: # define INC_IP(const_inc) ({ip+=(const_inc);})
258: # define DEF_CA
259: # define NEXT_P1
260: # define NEXT_P2 ({cfa=*ip++; goto *cfa;})
1.15 anton 261: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
1.3 anton 262: #endif
1.1 anton 263:
1.3 anton 264: /* direct threaded */
265: #else
1.1 anton 266: /* indirect THREADED */
267:
1.3 anton 268: #if THREADING_SCHEME==1
269: #warning indirect threading scheme 1: autoinc, long latency, cisc
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
276: # define NEXT_P1
277: # define NEXT_P2 ({goto **cfa;})
278: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
279: #endif
280:
1.3 anton 281: #if THREADING_SCHEME==2
282: #warning indirect threading scheme 2: autoinc, long latency
1.1 anton 283: # define NEXT_P0 ({cfa=*ip++;})
284: # define IP (ip-1)
1.3 anton 285: # define SET_IP(p) ({ip=(p); NEXT_P0;})
1.1 anton 286: # define NEXT_INST (cfa)
287: # define INC_IP(const_inc) ({cfa=IP[const_inc]; ip+=(const_inc);})
288: # define DEF_CA Label ca;
289: # define NEXT_P1 ({ca=*cfa;})
290: # define NEXT_P2 ({goto *ca;})
291: # define EXEC(XT) ({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
292: #endif
293:
294:
1.3 anton 295: #if THREADING_SCHEME==3
296: #warning indirect threading scheme 3: autoinc, low latency, cisc
1.1 anton 297: # define NEXT_P0
298: # define IP (ip)
1.3 anton 299: # define SET_IP(p) ({ip=(p); NEXT_P0;})
1.1 anton 300: # define NEXT_INST (*ip)
301: # define INC_IP(const_inc) ({ip+=(const_inc);})
302: # define DEF_CA
303: # define NEXT_P1
304: # define NEXT_P2 ({cfa=*ip++; goto **cfa;})
305: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
306: #endif
307:
1.3 anton 308: #if THREADING_SCHEME==4
309: #warning indirect threading scheme 4: autoinc, low latency
1.1 anton 310: # define NEXT_P0 ({cfa=*ip++;})
311: # define IP (ip-1)
1.3 anton 312: # define SET_IP(p) ({ip=(p); NEXT_P0;})
1.1 anton 313: # define NEXT_INST (cfa)
314: # define INC_IP(const_inc) ({cfa=IP[const_inc]; ip+=(const_inc);})
315: # define DEF_CA Label ca;
316: # define NEXT_P1 ({ca=*cfa;})
317: # define NEXT_P2 ({goto *ca;})
318: # define EXEC(XT) ({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
319: #endif
320:
321:
1.3 anton 322: #if THREADING_SCHEME==5
323: #warning indirect threading scheme 5: long latency, cisc
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
330: # define NEXT_P1 (ip++)
331: # define NEXT_P2 ({goto **cfa;})
332: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
333: #endif
334:
1.3 anton 335: #if THREADING_SCHEME==6
336: #warning indirect threading scheme 6: long latency
1.1 anton 337: # define NEXT_P0 ({cfa=*ip;})
338: # define IP (ip)
1.3 anton 339: # define SET_IP(p) ({ip=(p); NEXT_P0;})
1.1 anton 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
347:
1.3 anton 348: #if THREADING_SCHEME==7
349: #warning indirect threading scheme 7: low latency
350: # define NEXT_P0 ({cfa=*ip;})
351: # define IP (ip)
352: # define SET_IP(p) ({ip=(p); NEXT_P0;})
353: # define NEXT_INST (cfa)
354: # define INC_IP(const_inc) ({cfa=IP[const_inc]; ip+=(const_inc);})
355: # define DEF_CA Label ca;
356: # define NEXT_P1 ({ip++; ca=*cfa;})
357: # define NEXT_P2 ({goto *ca;})
358: # define EXEC(XT) ({DEF_CA cfa=(XT); ca=*cfa; goto *ca;})
359: #endif
1.1 anton 360:
1.3 anton 361: #if THREADING_SCHEME==8
362: #warning indirect threading scheme 8: low latency,cisc
1.1 anton 363: # define NEXT_P0
364: # define IP (ip)
1.3 anton 365: # define SET_IP(p) ({ip=(p); NEXT_P0;})
1.1 anton 366: # define NEXT_INST (*ip)
367: # define INC_IP(const_inc) ({ip+=(const_inc);})
368: # define DEF_CA
369: # define NEXT_P1
370: # define NEXT_P2 ({cfa=*ip++; goto **cfa;})
371: # define EXEC(XT) ({cfa=(XT); goto **cfa;})
372: #endif
373:
1.3 anton 374: /* indirect threaded */
1.1 anton 375: #endif
376:
1.16 ! anton 377: #endif /* !defined(DOUBLY_INDIRECT) && !defined(NO_IP) */
1.1 anton 378:
379: #define NEXT ({DEF_CA NEXT_P1; NEXT_P2;})
1.10 anton 380: #define IPTOS NEXT_INST
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