/* This file defines a number of threading schemes.
Copyright (C) 1995, 1996,1997,1999,2003,2004 Free Software Foundation, Inc.
This file is part of Gforth.
Gforth is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
This files defines macros for threading. Many sets of macros are
defined. Functionally they have only one difference: Some implement
direct threading, some indirect threading. The other differences are
just variations to help GCC generate faster code for various
machines.
(Well, to tell the truth, there actually is another functional
difference in some pathological cases: e.g., a '!' stores into the
cell where the next executed word comes from; or, the next word
executed comes from the top-of-stack. These differences are one of
the reasons why GCC cannot produce the right variation by itself. We
chose disallowing such practices and using the added implementation
freedom to achieve a significant speedup, because these practices
are not common in Forth (I have never heard of or seen anyone using
them), and it is easy to circumvent problems: A control flow change
will flush any prefetched words; you may want to do a "0
drop" before that to write back the top-of-stack cache.)
These macro sets are used in the following ways: After translation
to C a typical primitive looks like
...
{
DEF_CA
other declarations
NEXT_P0;
main part of the primitive
NEXT_P1;
store results to stack
NEXT_P2;
}
DEF_CA and all the NEXT_P* together must implement NEXT; In the main
part the instruction pointer can be read with IP, changed with
INC_IP(const_inc), and the cell right behind the presently executing
word (i.e. the value of *IP) is accessed with NEXT_INST.
If a primitive does not fall through the main part, it has to do the
rest by itself. If it changes ip, it has to redo NEXT_P0 (perhaps we
should define a macro SET_IP).
Some primitives (execute, dodefer) do not end with NEXT, but with
EXEC(.). If NEXT_P0 has been called earlier, it has to perform
"ip=IP;" to ensure that ip has the right value (NEXT_P0 may change
it).
Finally, there is NEXT1_P1 and NEXT1_P2, which are parts of EXEC
(EXEC(XT) could be defined as "cfa=XT; NEXT1_P1; NEXT1_P2;" (is this
true?)) and are used for making docol faster.
We can define the ways in which these macros are used with a regular
expression:
For a primitive
DEF_CA NEXT_P0 ( IP | INC_IP | NEXT_INST | ip=...; NEXT_P0 ) * ( NEXT_P1 NEXT_P2 | EXEC(...) )
For a run-time routine, e.g., docol:
PFA1(cfa) ( NEXT_P0 NEXT | cfa=...; NEXT1_P1; NEXT1_P2 | EXEC(...) )
This comment does not yet describe all the dependences that the
macros have to satisfy.
To organize the former ifdef chaos, each path is separated
This gives a quite impressive number of paths, but you clearly
find things that go together.
It should be possible to organize the whole thing in a way that
contains less redundancy and allows a simpler description.
*/
#ifdef GCC_PR15242_WORKAROUND
#define DO_GOTO goto before_goto
#else
#define DO_GOTO goto *real_ca
#endif
#ifndef GOTO_ALIGN
#define GOTO_ALIGN
#endif
#define GOTO(target) do {(real_ca=(target));} while(0)
#define NEXT_P2 do {NEXT_P1_5; DO_GOTO;} while(0)
#define EXEC(XT) do { EXEC1(XT); DO_GOTO;} while (0)
#define NEXT do {DEF_CA NEXT_P1; NEXT_P2;} while(0)
#define FIRST_NEXT_P2 NEXT_P1_5; GOTO_ALIGN; \
before_goto: goto *real_ca; after_goto:
#define FIRST_NEXT do {DEF_CA NEXT_P1; FIRST_NEXT_P2;} while(0)
#define IPTOS NEXT_INST
#ifdef DOUBLY_INDIRECT
# ifndef DEBUG_DITC
# define DEBUG_DITC 0
# endif
/* define to 1 if you want to check consistency */
# define NEXT_P0 do {cfa1=cfa; cfa=*ip;} while(0)
# define CFA cfa1
# define MORE_VARS Xt cfa1;
# define IP (ip)
# define SET_IP(p) do {ip=(p); cfa=*ip;} while(0)
# define NEXT_INST (cfa)
# define INC_IP(const_inc) do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
# define DEF_CA Label ca;
# define NEXT_P1 do {\
if (DEBUG_DITC && (cfa<=vm_prims+DOESJUMP || cfa>=vm_prims+npriminfos)) \
fprintf(stderr,"NEXT encountered prim %p at ip=%p\n", cfa, ip); \
ip++;} while(0)
# define NEXT_P1_5 do {ca=**cfa; GOTO(ca);} while(0)
# define EXEC1(XT) do {DEF_CA cfa=(XT);\
if (DEBUG_DITC && (cfa>vm_prims+DOESJUMP && cfa<vm_prims+npriminfos)) \
fprintf(stderr,"EXEC encountered xt %p at ip=%p, vm_prims=%p, xts=%p\n", cfa, ip, vm_prims, xts); \
ca=**cfa; GOTO(ca);} while(0)
#elif defined(NO_IP)
#define NEXT_P0
# define CFA cfa
#define SET_IP(target) assert(0)
#define INC_IP(n) ((void)0)
#define DEF_CA
#define NEXT_P1
#define NEXT_P1_5 do {goto *next_code;} while(0)
/* set next_code to the return address before performing EXEC */
#define EXEC1(XT) do {cfa=(XT); goto **cfa;} while(0)
#else /* !defined(DOUBLY_INDIRECT) && !defined(NO_IP) */
#if defined(DIRECT_THREADED)
/* This lets the compiler know that cfa is dead before; we place it at
"goto *"s that perform direct threaded dispatch (i.e., not EXECUTE
etc.), and thus do not reach doers, which would use cfa; the only
way to a doer is through EXECUTE etc., which set the cfa
themselves.
Some of these direct threaded schemes use "cfa" to hold the code
address in normal direct threaded code. Of course we cannot use
KILLS there.
KILLS works by having an empty asm instruction, and claiming to the
compiler that it writes to cfa.
KILLS is optional. You can write
#define KILLS
and lose just a little performance.
*/
#define KILLS asm("":"=X"(cfa));
#ifndef THREADING_SCHEME
#define THREADING_SCHEME 7
#endif
#if THREADING_SCHEME==1
#warning direct threading scheme 1: autoinc, long latency, cfa live
# define NEXT_P0 do {cfa1=cfa; cfa=*ip++;} while(0)
# define CFA cfa1
# define MORE_VARS Xt cfa1;
# define IP (ip-1)
# define SET_IP(p) do {ip=(p); cfa=*ip++;} while(0)
# define NEXT_INST (cfa)
# define INC_IP(const_inc) do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1
# define NEXT_P1_5 do {GOTO(cfa);} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
#endif
#if THREADING_SCHEME==2
#warning direct threading scheme 2: autoinc, long latency, cfa dead
# define NEXT_P0 (ip++)
# define CFA cfa
# define IP (ip-1)
# define SET_IP(p) do {ip=(p); NEXT_P0;} while(0)
# define NEXT_INST (*(ip-1))
# define INC_IP(const_inc) do { ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1
# define NEXT_P1_5 do {KILLS GOTO(*(ip-1));} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
#endif
#if THREADING_SCHEME==3
#warning direct threading scheme 3: autoinc, low latency, cfa live
# define NEXT_P0
# define CFA cfa
# define IP (ip)
# define SET_IP(p) do {ip=(p); NEXT_P0;} while(0)
# define NEXT_INST (*ip)
# define INC_IP(const_inc) do {ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1 do {cfa=*ip++;} while(0)
# define NEXT_P1_5 do {GOTO(cfa);} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
#endif
#if THREADING_SCHEME==4
#warning direct threading scheme 4: autoinc, low latency, cfa dead
# define NEXT_P0
# define CFA cfa
# define IP (ip)
# define SET_IP(p) do {ip=(p); NEXT_P0;} while(0)
# define NEXT_INST (*ip)
# define INC_IP(const_inc) do { ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1
# define NEXT_P1_5 do {KILLS GOTO(*(ip++));} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
#endif
#if THREADING_SCHEME==5
#warning direct threading scheme 5: long latency, cfa live
# define NEXT_P0 do {cfa1=cfa; cfa=*ip;} while(0)
# define CFA cfa1
# define MORE_VARS Xt cfa1;
# define IP (ip)
# define SET_IP(p) do {ip=(p); cfa=*ip;} while(0)
# define NEXT_INST (cfa)
# define INC_IP(const_inc) do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1 (ip++)
# define NEXT_P1_5 do {GOTO(cfa);} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
#endif
#if THREADING_SCHEME==6
#warning direct threading scheme 6: long latency, cfa dead
# define NEXT_P0
# define CFA cfa
# define IP (ip)
# define SET_IP(p) do {ip=(p); NEXT_P0;} while(0)
# define NEXT_INST (*ip)
# define INC_IP(const_inc) do {ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1 (ip++)
# define NEXT_P1_5 do {KILLS GOTO(*(ip-1));} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
#endif
#if THREADING_SCHEME==7
#warning direct threading scheme 7: low latency, cfa live
# define NEXT_P0
# define CFA cfa
# define IP (ip)
# define SET_IP(p) do {ip=(p); NEXT_P0;} while(0)
# define NEXT_INST (*ip)
# define INC_IP(const_inc) do {ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1 do {cfa=*ip++;} while(0)
# define NEXT_P1_5 do {GOTO(cfa);} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
#endif
#if THREADING_SCHEME==8
#warning direct threading scheme 8: cfa dead, i386 hack
# define NEXT_P0
# define CFA cfa
# define IP (ip)
# define SET_IP(p) do {ip=(p); NEXT_P0;} while(0)
# define NEXT_INST (*IP)
# define INC_IP(const_inc) do { ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1 (ip++)
# define NEXT_P1_5 do {KILLS GOTO(*(ip-1));} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
#endif
#if THREADING_SCHEME==9
#warning direct threading scheme 9: Power/PPC hack, long latency
/* Power uses a prepare-to-branch instruction, and the latency between
this inst and the branch is 5 cycles on a PPC604; so we utilize this
to do some prefetching in between */
# define NEXT_P0
# define CFA cfa
# define IP ip
# define SET_IP(p) do {ip=(p); next_cfa=*ip; NEXT_P0;} while(0)
# define NEXT_INST (next_cfa)
# define INC_IP(const_inc) do {next_cfa=IP[const_inc]; ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1 do {cfa=next_cfa; ip++; next_cfa=*ip;} while(0)
# define NEXT_P1_5 do {GOTO(cfa);} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
# define MORE_VARS Xt next_cfa;
#endif
#if THREADING_SCHEME==10
#warning direct threading scheme 10: plain (no attempt at scheduling)
# define NEXT_P0
# define CFA cfa
# define IP (ip)
# define SET_IP(p) do {ip=(p); NEXT_P0;} while(0)
# define NEXT_INST (*ip)
# define INC_IP(const_inc) do {ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1
# define NEXT_P1_5 do {cfa=*ip++; GOTO(cfa);} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
#endif
/* direct threaded */
#else
/* indirect THREADED */
#ifndef THREADING_SCHEME
#define THREADING_SCHEME 6
#endif
#if THREADING_SCHEME==1
#warning indirect threading scheme 1: autoinc, long latency, cisc
# define NEXT_P0 do {cfa1=cfa; cfa=*ip++;} while(0)
# define CFA cfa1
# define MORE_VARS Xt cfa1;
# define IP (ip-1)
# define SET_IP(p) do {ip=(p); cfa=*ip++;} while(0)
# define NEXT_INST (cfa)
# define INC_IP(const_inc) do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1
# define NEXT_P1_5 do {GOTO(*cfa);} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
#endif
#if THREADING_SCHEME==2
#warning indirect threading scheme 2: autoinc, long latency
# define NEXT_P0 do {cfa1=cfa; cfa=*ip++;} while(0)
# define CFA cfa1
# define MORE_VARS Xt cfa1;
# define IP (ip-1)
# define SET_IP(p) do {ip=(p); cfa=*ip++;} while(0)
# define NEXT_INST (cfa)
# define INC_IP(const_inc) do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
# define DEF_CA Label ca;
# define NEXT_P1 do {ca=*cfa;} while(0)
# define NEXT_P1_5 do {GOTO(ca);} while(0)
# define EXEC1(XT) do {DEF_CA cfa=(XT); ca=*cfa; GOTO(ca);} while(0)
#endif
#if THREADING_SCHEME==3
#warning indirect threading scheme 3: autoinc, low latency, cisc
# define NEXT_P0
# define CFA cfa
# define IP (ip)
# define SET_IP(p) do {ip=(p); NEXT_P0;} while(0)
# define NEXT_INST (*ip)
# define INC_IP(const_inc) do {ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1
# define NEXT_P1_5 do {cfa=*ip++; GOTO(*cfa);} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
#endif
#if THREADING_SCHEME==4
#warning indirect threading scheme 4: autoinc, low latency
# define NEXT_P0 do {cfa1=cfa; cfa=*ip++;} while(0)
# define CFA cfa1
# define MORE_VARS Xt cfa1;
# define IP (ip-1)
# define SET_IP(p) do {ip=(p); cfa=*ip++;} while(0)
# define NEXT_INST (cfa)
# define INC_IP(const_inc) do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
# define DEF_CA Label ca;
# define NEXT_P1 do {ca=*cfa;} while(0)
# define NEXT_P1_5 do {GOTO(ca);} while(0)
# define EXEC1(XT) do {DEF_CA cfa=(XT); ca=*cfa; GOTO(ca);} while(0)
#endif
#if THREADING_SCHEME==5
#warning indirect threading scheme 5: long latency, cisc
# define NEXT_P0 do {cfa1=cfa; cfa=*ip;} while(0)
# define CFA cfa1
# define MORE_VARS Xt cfa1;
# define IP (ip)
# define SET_IP(p) do {ip=(p); cfa=*ip;} while(0)
# define NEXT_INST (cfa)
# define INC_IP(const_inc) do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1 (ip++)
# define NEXT_P1_5 do {GOTO(*cfa);} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
#endif
#if THREADING_SCHEME==6
#warning indirect threading scheme 6: long latency
# define NEXT_P0 do {cfa1=cfa; cfa=*ip;} while(0)
# define CFA cfa1
# define MORE_VARS Xt cfa1;
# define IP (ip)
# define SET_IP(p) do {ip=(p); cfa=*ip;} while(0)
# define NEXT_INST (cfa)
# define INC_IP(const_inc) do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
# define DEF_CA Label ca;
# define NEXT_P1 do {ip++; ca=*cfa;} while(0)
# define NEXT_P1_5 do {GOTO(ca);} while(0)
# define EXEC1(XT) do {DEF_CA cfa=(XT); ca=*cfa; GOTO(ca);} while(0)
#endif
#if THREADING_SCHEME==7
#warning indirect threading scheme 7: low latency
# define NEXT_P0 do {cfa1=cfa; cfa=*ip;} while(0)
# define CFA cfa1
# define MORE_VARS Xt cfa1;
# define IP (ip)
# define SET_IP(p) do {ip=(p); cfa=*ip;} while(0)
# define NEXT_INST (cfa)
# define INC_IP(const_inc) do {cfa=IP[const_inc]; ip+=(const_inc);} while(0)
# define DEF_CA Label ca;
# define NEXT_P1 do {ip++; ca=*cfa;} while(0)
# define NEXT_P1_5 do {GOTO(ca);} while(0)
# define EXEC1(XT) do {DEF_CA cfa=(XT); ca=*cfa; GOTO(ca);} while(0)
#endif
#if THREADING_SCHEME==8
#warning indirect threading scheme 8: low latency,cisc
# define NEXT_P0
# define CFA cfa
# define IP (ip)
# define SET_IP(p) do {ip=(p); NEXT_P0;} while(0)
# define NEXT_INST (*ip)
# define INC_IP(const_inc) do {ip+=(const_inc);} while(0)
# define DEF_CA
# define NEXT_P1
# define NEXT_P1_5 do {cfa=*ip++; GOTO(*cfa);} while(0)
# define EXEC1(XT) do {cfa=(XT); GOTO(*cfa);} while(0)
#endif
/* indirect threaded */
#endif
#endif /* !defined(DOUBLY_INDIRECT) && !defined(NO_IP) */
FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>