1 /* Functions for manipulating expressions designed to be executed on the agent
2 Copyright (C) 1998, 1999, 2000, 2007, 2008, 2009, 2010, 2011
3 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
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.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
20 /* Despite what the above comment says about this file being part of
21 GDB, we would like to keep these functions free of GDB
22 dependencies, since we want to be able to use them in contexts
23 outside of GDB (test suites, the stub, etc.) */
29 #include "gdb_string.h"
31 #include "user-regs.h"
33 static void grow_expr (struct agent_expr
*x
, int n
);
35 static void append_const (struct agent_expr
*x
, LONGEST val
, int n
);
37 static LONGEST
read_const (struct agent_expr
*x
, int o
, int n
);
39 static void generic_ext (struct agent_expr
*x
, enum agent_op op
, int n
);
41 /* Functions for building expressions. */
43 /* Allocate a new, empty agent expression. */
45 new_agent_expr (struct gdbarch
*gdbarch
, CORE_ADDR scope
)
47 struct agent_expr
*x
= xmalloc (sizeof (*x
));
50 x
->size
= 1; /* Change this to a larger value once
51 reallocation code is tested. */
52 x
->buf
= xmalloc (x
->size
);
57 /* Bit vector for registers used. */
59 x
->reg_mask
= xmalloc (x
->reg_mask_len
* sizeof (x
->reg_mask
[0]));
60 memset (x
->reg_mask
, 0, x
->reg_mask_len
* sizeof (x
->reg_mask
[0]));
65 /* Free a agent expression. */
67 free_agent_expr (struct agent_expr
*x
)
75 do_free_agent_expr_cleanup (void *x
)
81 make_cleanup_free_agent_expr (struct agent_expr
*x
)
83 return make_cleanup (do_free_agent_expr_cleanup
, x
);
87 /* Make sure that X has room for at least N more bytes. This doesn't
88 affect the length, just the allocated size. */
90 grow_expr (struct agent_expr
*x
, int n
)
92 if (x
->len
+ n
> x
->size
)
95 if (x
->size
< x
->len
+ n
)
96 x
->size
= x
->len
+ n
+ 10;
97 x
->buf
= xrealloc (x
->buf
, x
->size
);
102 /* Append the low N bytes of VAL as an N-byte integer to the
103 expression X, in big-endian order. */
105 append_const (struct agent_expr
*x
, LONGEST val
, int n
)
110 for (i
= n
- 1; i
>= 0; i
--)
112 x
->buf
[x
->len
+ i
] = val
& 0xff;
119 /* Extract an N-byte big-endian unsigned integer from expression X at
122 read_const (struct agent_expr
*x
, int o
, int n
)
127 /* Make sure we're not reading off the end of the expression. */
129 error (_("GDB bug: ax-general.c (read_const): incomplete constant"));
131 for (i
= 0; i
< n
; i
++)
132 accum
= (accum
<< 8) | x
->buf
[o
+ i
];
138 /* Append a simple operator OP to EXPR. */
140 ax_simple (struct agent_expr
*x
, enum agent_op op
)
143 x
->buf
[x
->len
++] = op
;
146 /* Append a pick operator to EXPR. DEPTH is the stack item to pick,
147 with 0 being top of stack. */
150 ax_pick (struct agent_expr
*x
, int depth
)
152 if (depth
< 0 || depth
> 255)
153 error (_("GDB bug: ax-general.c (ax_pick): stack depth out of range"));
154 ax_simple (x
, aop_pick
);
155 append_const (x
, 1, depth
);
159 /* Append a sign-extension or zero-extension instruction to EXPR, to
160 extend an N-bit value. */
162 generic_ext (struct agent_expr
*x
, enum agent_op op
, int n
)
164 /* N must fit in a byte. */
165 if (n
< 0 || n
> 255)
166 error (_("GDB bug: ax-general.c (generic_ext): bit count out of range"));
167 /* That had better be enough range. */
168 if (sizeof (LONGEST
) * 8 > 255)
169 error (_("GDB bug: ax-general.c (generic_ext): "
170 "opcode has inadequate range"));
173 x
->buf
[x
->len
++] = op
;
174 x
->buf
[x
->len
++] = n
;
178 /* Append a sign-extension instruction to EXPR, to extend an N-bit value. */
180 ax_ext (struct agent_expr
*x
, int n
)
182 generic_ext (x
, aop_ext
, n
);
186 /* Append a zero-extension instruction to EXPR, to extend an N-bit value. */
188 ax_zero_ext (struct agent_expr
*x
, int n
)
190 generic_ext (x
, aop_zero_ext
, n
);
194 /* Append a trace_quick instruction to EXPR, to record N bytes. */
196 ax_trace_quick (struct agent_expr
*x
, int n
)
198 /* N must fit in a byte. */
199 if (n
< 0 || n
> 255)
200 error (_("GDB bug: ax-general.c (ax_trace_quick): "
201 "size out of range for trace_quick"));
204 x
->buf
[x
->len
++] = aop_trace_quick
;
205 x
->buf
[x
->len
++] = n
;
209 /* Append a goto op to EXPR. OP is the actual op (must be aop_goto or
210 aop_if_goto). We assume we don't know the target offset yet,
211 because it's probably a forward branch, so we leave space in EXPR
212 for the target, and return the offset in EXPR of that space, so we
213 can backpatch it once we do know the target offset. Use ax_label
214 to do the backpatching. */
216 ax_goto (struct agent_expr
*x
, enum agent_op op
)
219 x
->buf
[x
->len
+ 0] = op
;
220 x
->buf
[x
->len
+ 1] = 0xff;
221 x
->buf
[x
->len
+ 2] = 0xff;
226 /* Suppose a given call to ax_goto returns some value PATCH. When you
227 know the offset TARGET that goto should jump to, call
228 ax_label (EXPR, PATCH, TARGET)
229 to patch TARGET into the ax_goto instruction. */
231 ax_label (struct agent_expr
*x
, int patch
, int target
)
233 /* Make sure the value is in range. Don't accept 0xffff as an
234 offset; that's our magic sentinel value for unpatched branches. */
235 if (target
< 0 || target
>= 0xffff)
236 error (_("GDB bug: ax-general.c (ax_label): label target out of range"));
238 x
->buf
[patch
] = (target
>> 8) & 0xff;
239 x
->buf
[patch
+ 1] = target
& 0xff;
243 /* Assemble code to push a constant on the stack. */
245 ax_const_l (struct agent_expr
*x
, LONGEST l
)
247 static enum agent_op ops
[]
249 {aop_const8
, aop_const16
, aop_const32
, aop_const64
};
253 /* How big is the number? 'op' keeps track of which opcode to use.
254 Notice that we don't really care whether the original number was
255 signed or unsigned; we always reproduce the value exactly, and
256 use the shortest representation. */
257 for (op
= 0, size
= 8; size
< 64; size
*= 2, op
++)
259 LONGEST lim
= ((LONGEST
) 1) << (size
- 1);
261 if (-lim
<= l
&& l
<= lim
- 1)
265 /* Emit the right opcode... */
266 ax_simple (x
, ops
[op
]);
268 /* Emit the low SIZE bytes as an unsigned number. We know that
269 sign-extending this will yield l. */
270 append_const (x
, l
, size
/ 8);
272 /* Now, if it was negative, and not full-sized, sign-extend it. */
273 if (l
< 0 && size
< 64)
279 ax_const_d (struct agent_expr
*x
, LONGEST d
)
281 /* FIXME: floating-point support not present yet. */
282 error (_("GDB bug: ax-general.c (ax_const_d): "
283 "floating point not supported yet"));
287 /* Assemble code to push the value of register number REG on the
290 ax_reg (struct agent_expr
*x
, int reg
)
292 if (reg
>= gdbarch_num_regs (x
->gdbarch
))
294 /* This is a pseudo-register. */
295 if (!gdbarch_ax_pseudo_register_push_stack_p (x
->gdbarch
))
296 error (_("'%s' is a pseudo-register; "
297 "GDB cannot yet trace its contents."),
298 user_reg_map_regnum_to_name (x
->gdbarch
, reg
));
299 if (gdbarch_ax_pseudo_register_push_stack (x
->gdbarch
, x
, reg
))
300 error (_("Trace '%s' failed."),
301 user_reg_map_regnum_to_name (x
->gdbarch
, reg
));
305 /* Make sure the register number is in range. */
306 if (reg
< 0 || reg
> 0xffff)
307 error (_("GDB bug: ax-general.c (ax_reg): "
308 "register number out of range"));
310 x
->buf
[x
->len
] = aop_reg
;
311 x
->buf
[x
->len
+ 1] = (reg
>> 8) & 0xff;
312 x
->buf
[x
->len
+ 2] = (reg
) & 0xff;
317 /* Assemble code to operate on a trace state variable. */
320 ax_tsv (struct agent_expr
*x
, enum agent_op op
, int num
)
322 /* Make sure the tsv number is in range. */
323 if (num
< 0 || num
> 0xffff)
324 internal_error (__FILE__
, __LINE__
,
325 _("ax-general.c (ax_tsv): variable "
326 "number is %d, out of range"), num
);
330 x
->buf
[x
->len
+ 1] = (num
>> 8) & 0xff;
331 x
->buf
[x
->len
+ 2] = (num
) & 0xff;
337 /* Functions for disassembling agent expressions, and otherwise
338 debugging the expression compiler. */
340 struct aop_map aop_map
[] =
343 #define DEFOP(NAME, SIZE, DATA_SIZE, CONSUMED, PRODUCED, VALUE) \
344 , { # NAME, SIZE, DATA_SIZE, CONSUMED, PRODUCED }
350 /* Disassemble the expression EXPR, writing to F. */
352 ax_print (struct ui_file
*f
, struct agent_expr
*x
)
357 fprintf_filtered (f
, _("Scope: %s\n"), paddress (x
->gdbarch
, x
->scope
));
358 fprintf_filtered (f
, _("Reg mask:"));
359 for (i
= 0; i
< x
->reg_mask_len
; ++i
)
360 fprintf_filtered (f
, _(" %02x"), x
->reg_mask
[i
]);
361 fprintf_filtered (f
, _("\n"));
363 /* Check the size of the name array against the number of entries in
364 the enum, to catch additions that people didn't sync. */
365 if ((sizeof (aop_map
) / sizeof (aop_map
[0]))
367 error (_("GDB bug: ax-general.c (ax_print): opcode map out of sync"));
369 for (i
= 0; i
< x
->len
;)
371 enum agent_op op
= x
->buf
[i
];
373 if (op
>= (sizeof (aop_map
) / sizeof (aop_map
[0]))
374 || !aop_map
[op
].name
)
376 fprintf_filtered (f
, _("%3d <bad opcode %02x>\n"), i
, op
);
380 if (i
+ 1 + aop_map
[op
].op_size
> x
->len
)
382 fprintf_filtered (f
, _("%3d <incomplete opcode %s>\n"),
383 i
, aop_map
[op
].name
);
387 fprintf_filtered (f
, "%3d %s", i
, aop_map
[op
].name
);
388 if (aop_map
[op
].op_size
> 0)
390 fputs_filtered (" ", f
);
392 print_longest (f
, 'd', 0,
393 read_const (x
, i
+ 1, aop_map
[op
].op_size
));
395 fprintf_filtered (f
, "\n");
396 i
+= 1 + aop_map
[op
].op_size
;
398 is_float
= (op
== aop_float
);
402 /* Add register REG to the register mask for expression AX. */
404 ax_reg_mask (struct agent_expr
*ax
, int reg
)
406 if (reg
>= gdbarch_num_regs (ax
->gdbarch
))
408 /* This is a pseudo-register. */
409 if (!gdbarch_ax_pseudo_register_collect_p (ax
->gdbarch
))
410 error (_("'%s' is a pseudo-register; "
411 "GDB cannot yet trace its contents."),
412 user_reg_map_regnum_to_name (ax
->gdbarch
, reg
));
413 if (gdbarch_ax_pseudo_register_collect (ax
->gdbarch
, ax
, reg
))
414 error (_("Trace '%s' failed."),
415 user_reg_map_regnum_to_name (ax
->gdbarch
, reg
));
421 /* Grow the bit mask if necessary. */
422 if (byte
>= ax
->reg_mask_len
)
424 /* It's not appropriate to double here. This isn't a
426 int new_len
= byte
+ 1;
427 unsigned char *new_reg_mask
= xrealloc (ax
->reg_mask
,
429 * sizeof (ax
->reg_mask
[0]));
430 memset (new_reg_mask
+ ax
->reg_mask_len
, 0,
431 (new_len
- ax
->reg_mask_len
) * sizeof (ax
->reg_mask
[0]));
432 ax
->reg_mask_len
= new_len
;
433 ax
->reg_mask
= new_reg_mask
;
436 ax
->reg_mask
[byte
] |= 1 << (reg
% 8);
440 /* Given an agent expression AX, fill in requirements and other descriptive
443 ax_reqs (struct agent_expr
*ax
)
448 /* Jump target table. targets[i] is non-zero iff we have found a
450 char *targets
= (char *) alloca (ax
->len
* sizeof (targets
[0]));
452 /* Instruction boundary table. boundary[i] is non-zero iff our scan
453 has reached an instruction starting at offset i. */
454 char *boundary
= (char *) alloca (ax
->len
* sizeof (boundary
[0]));
456 /* Stack height record. If either targets[i] or boundary[i] is
457 non-zero, heights[i] is the height the stack should have before
458 executing the bytecode at that point. */
459 int *heights
= (int *) alloca (ax
->len
* sizeof (heights
[0]));
461 /* Pointer to a description of the present op. */
464 memset (targets
, 0, ax
->len
* sizeof (targets
[0]));
465 memset (boundary
, 0, ax
->len
* sizeof (boundary
[0]));
467 ax
->max_height
= ax
->min_height
= height
= 0;
468 ax
->flaw
= agent_flaw_none
;
469 ax
->max_data_size
= 0;
471 for (i
= 0; i
< ax
->len
; i
+= 1 + op
->op_size
)
473 if (ax
->buf
[i
] > (sizeof (aop_map
) / sizeof (aop_map
[0])))
475 ax
->flaw
= agent_flaw_bad_instruction
;
479 op
= &aop_map
[ax
->buf
[i
]];
483 ax
->flaw
= agent_flaw_bad_instruction
;
487 if (i
+ 1 + op
->op_size
> ax
->len
)
489 ax
->flaw
= agent_flaw_incomplete_instruction
;
493 /* If this instruction is a forward jump target, does the
494 current stack height match the stack height at the jump
496 if (targets
[i
] && (heights
[i
] != height
))
498 ax
->flaw
= agent_flaw_height_mismatch
;
505 height
-= op
->consumed
;
506 if (height
< ax
->min_height
)
507 ax
->min_height
= height
;
508 height
+= op
->produced
;
509 if (height
> ax
->max_height
)
510 ax
->max_height
= height
;
512 if (op
->data_size
> ax
->max_data_size
)
513 ax
->max_data_size
= op
->data_size
;
515 /* For jump instructions, check that the target is a valid
516 offset. If it is, record the fact that that location is a
517 jump target, and record the height we expect there. */
518 if (aop_goto
== op
- aop_map
519 || aop_if_goto
== op
- aop_map
)
521 int target
= read_const (ax
, i
+ 1, 2);
522 if (target
< 0 || target
>= ax
->len
)
524 ax
->flaw
= agent_flaw_bad_jump
;
528 /* Do we have any information about what the stack height
529 should be at the target? */
530 if (targets
[target
] || boundary
[target
])
532 if (heights
[target
] != height
)
534 ax
->flaw
= agent_flaw_height_mismatch
;
539 /* Record the target, along with the stack height we expect. */
541 heights
[target
] = height
;
544 /* For unconditional jumps with a successor, check that the
545 successor is a target, and pick up its stack height. */
546 if (aop_goto
== op
- aop_map
551 ax
->flaw
= agent_flaw_hole
;
555 height
= heights
[i
+ 3];
558 /* For reg instructions, record the register in the bit mask. */
559 if (aop_reg
== op
- aop_map
)
561 int reg
= read_const (ax
, i
+ 1, 2);
563 ax_reg_mask (ax
, reg
);
567 /* Check that all the targets are on boundaries. */
568 for (i
= 0; i
< ax
->len
; i
++)
569 if (targets
[i
] && !boundary
[i
])
571 ax
->flaw
= agent_flaw_bad_jump
;
575 ax
->final_height
= height
;