1: /* front-end compiler for vmgen example
2:
3: Copyright (C) 2001,2002 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: /* I use yacc/bison here not because I think it's the best tool for
23: the job, but because it's widely available and popular; it's also
24: (barely) adequate for this job. */
25:
26: %{
27: #include <stdlib.h>
28: #include <stdio.h>
29: #include <string.h>
30: #include "mini.h"
31:
32: /* BB_BOUNDARY is needed on basic blocks without a preceding VM branch */
33: #define BB_BOUNDARY (last_compiled = NULL, /* suppress peephole opt */ \
34: block_insert(vmcodep)) /* for accurate profiling */
35:
36: Label *vm_prim;
37: Inst *vmcodep;
38: FILE *vm_out;
39: int vm_debug;
40:
41: void yyerror(char *s)
42: {
43: fprintf (stderr, "%s: %d: %s\n", program_name, yylineno, s);
44: }
45:
46: #include "mini-gen.i"
47:
48: void gen_main_end(void)
49: {
50: gen_call(&vmcodep, func_addr("main"), func_calladjust("main"));
51: gen_end(&vmcodep);
52: BB_BOUNDARY; /* for profiling; see comment in mini.vmg:end */
53: }
54:
55: int locals=0;
56: int nonparams=0;
57:
58: int yylex();
59: %}
60:
61:
62: %token FUNC RETURN END VAR IF THEN ELSE WHILE DO BECOMES PRINT NUM IDENT
63:
64: %union {
65: long num;
66: char *string;
67: Inst *instp;
68: }
69:
70: %type <string> IDENT;
71: %type <num> NUM;
72: %type <instp> elsepart;
73:
74:
75: %%
76: program: program function
77: | ;
78:
79: function: FUNC IDENT { locals=0; nonparams=0; } '(' params ')'
80: vars { insert_func($2,vmcodep,locals,nonparams); }
81: stats RETURN expr ';'
82: END FUNC ';' { gen_return(&vmcodep, -adjust(locals)); }
83: ;
84:
85: params: IDENT ',' { insert_local($1); } params
86: | IDENT { insert_local($1); }
87: | ;
88:
89: vars: vars VAR IDENT ';' { insert_local($3); nonparams++; }
90: | ;
91:
92: stats: stats stat ';'
93: | ;
94:
95: stat: IF expr THEN { gen_zbranch(&vmcodep, 0); $<instp>$ = vmcodep; }
96: stats { $<instp>$ = $<instp>4; }
97: elsepart END IF { BB_BOUNDARY; vm_target2Cell(vmcodep, $<instp>7[-1]); }
98: | WHILE { BB_BOUNDARY; $<instp>$ = vmcodep; }
99: expr DO { gen_zbranch(&vmcodep, 0); $<instp>$ = vmcodep; }
100: stats END WHILE { gen_branch(&vmcodep, $<instp>2); vm_target2Cell(vmcodep, $<instp>5[-1]); }
101: | IDENT BECOMES expr { gen_storelocal(&vmcodep, var_offset($1)); }
102: | PRINT expr { gen_print(&vmcodep); }
103: | expr { gen_drop(&vmcodep); }
104: ;
105:
106: elsepart: ELSE { gen_branch(&vmcodep, 0); $<instp>$ = vmcodep; vm_target2Cell(vmcodep, $<instp>0[-1]); }
107: stats { $$ = $<instp>2; }
108: | { $$ = $<instp>0; }
109: ;
110:
111: expr: term '+' term { gen_add(&vmcodep); }
112: | term '-' term { gen_sub(&vmcodep); }
113: | term '*' term { gen_mul(&vmcodep); }
114: | term '&' term { gen_and(&vmcodep); }
115: | term '|' term { gen_or(&vmcodep); }
116: | term '<' term { gen_lessthan(&vmcodep); }
117: | term '=' term { gen_equals(&vmcodep); }
118: | '!' term { gen_not(&vmcodep); }
119: | '-' term { gen_negate(&vmcodep); }
120: | term
121: ;
122:
123: term: '(' expr ')'
124: | IDENT '(' args ')' { gen_call(&vmcodep, func_addr($1), func_calladjust($1)); }
125: | IDENT { gen_loadlocal(&vmcodep, var_offset($1)); }
126: | NUM { gen_lit(&vmcodep, $1); }
127: ;
128:
129: /* missing: argument counting and checking against called function */
130: args: expr ',' args
131: | expr
132: | ;
133: %%
134: int yywrap(void)
135: {
136: return 1;
137: }
138:
139: #include "lex.yy.c"
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