1 /* GDB-specific functions for operating on agent expressions
2 Copyright 1998 Free Software Foundation, Inc.
4 This file is part of GDB.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
26 #include "expression.h"
34 /* Probably the best way to read this file is to start with the types
35 and enums in ax-gdb.h, and then look at gen_expr, towards the
36 bottom; that's the main function that looks at the GDB expressions
37 and calls everything else to generate code.
39 I'm beginning to wonder whether it wouldn't be nicer to internally
40 generate trees, with types, and then spit out the bytecode in
41 linear form afterwards; we could generate fewer `swap', `ext', and
42 `zero_ext' bytecodes that way; it would make good constant folding
43 easier, too. But at the moment, I think we should be willing to
44 pay for the simplicity of this code with less-than-optimal bytecode
47 Remember, "GBD" stands for "Great Britain, Dammit!" So be careful. */
51 /* Prototypes for local functions. */
53 /* There's a standard order to the arguments of these functions:
54 union exp_element ** --- pointer into expression
55 struct agent_expr * --- agent expression buffer to generate code into
56 struct axs_value * --- describes value left on top of stack */
58 static struct value
*const_var_ref
PARAMS ((struct symbol
* var
));
59 static struct value
*const_expr
PARAMS ((union exp_element
** pc
));
60 static struct value
*maybe_const_expr
PARAMS ((union exp_element
** pc
));
62 static void gen_traced_pop
PARAMS ((struct agent_expr
*, struct axs_value
*));
64 static void gen_sign_extend
PARAMS ((struct agent_expr
*, struct type
*));
65 static void gen_extend
PARAMS ((struct agent_expr
*, struct type
*));
66 static void gen_fetch
PARAMS ((struct agent_expr
*, struct type
*));
67 static void gen_left_shift
PARAMS ((struct agent_expr
*, int));
70 static void gen_frame_args_address
PARAMS ((struct agent_expr
*));
71 static void gen_frame_locals_address
PARAMS ((struct agent_expr
*));
72 static void gen_offset
PARAMS ((struct agent_expr
* ax
, int offset
));
73 static void gen_sym_offset
PARAMS ((struct agent_expr
*, struct symbol
*));
74 static void gen_var_ref
PARAMS ((struct agent_expr
* ax
,
75 struct axs_value
* value
,
76 struct symbol
* var
));
79 static void gen_int_literal
PARAMS ((struct agent_expr
* ax
,
80 struct axs_value
* value
,
81 LONGEST k
, struct type
* type
));
84 static void require_rvalue
PARAMS ((struct agent_expr
* ax
,
85 struct axs_value
* value
));
86 static void gen_usual_unary
PARAMS ((struct agent_expr
* ax
,
87 struct axs_value
* value
));
88 static int type_wider_than
PARAMS ((struct type
* type1
,
89 struct type
* type2
));
90 static struct type
*max_type
PARAMS ((struct type
* type1
,
91 struct type
* type2
));
92 static void gen_conversion
PARAMS ((struct agent_expr
* ax
,
95 static int is_nontrivial_conversion
PARAMS ((struct type
* from
,
97 static void gen_usual_arithmetic
PARAMS ((struct agent_expr
* ax
,
98 struct axs_value
* value1
,
99 struct axs_value
* value2
));
100 static void gen_integral_promotions
PARAMS ((struct agent_expr
* ax
,
101 struct axs_value
* value
));
102 static void gen_cast
PARAMS ((struct agent_expr
* ax
,
103 struct axs_value
* value
,
104 struct type
* type
));
105 static void gen_scale
PARAMS ((struct agent_expr
* ax
,
107 struct type
* type
));
108 static void gen_add
PARAMS ((struct agent_expr
* ax
,
109 struct axs_value
* value
,
110 struct axs_value
* value1
,
111 struct axs_value
* value2
,
113 static void gen_sub
PARAMS ((struct agent_expr
* ax
,
114 struct axs_value
* value
,
115 struct axs_value
* value1
,
116 struct axs_value
* value2
));
117 static void gen_binop
PARAMS ((struct agent_expr
* ax
,
118 struct axs_value
* value
,
119 struct axs_value
* value1
,
120 struct axs_value
* value2
,
122 enum agent_op op_unsigned
,
125 static void gen_logical_not
PARAMS ((struct agent_expr
* ax
,
126 struct axs_value
* value
));
127 static void gen_complement
PARAMS ((struct agent_expr
* ax
,
128 struct axs_value
* value
));
129 static void gen_deref
PARAMS ((struct agent_expr
*, struct axs_value
*));
130 static void gen_address_of
PARAMS ((struct agent_expr
*, struct axs_value
*));
131 static int find_field
PARAMS ((struct type
* type
, char *name
));
132 static void gen_bitfield_ref
PARAMS ((struct agent_expr
* ax
,
133 struct axs_value
* value
,
135 int start
, int end
));
136 static void gen_struct_ref
PARAMS ((struct agent_expr
* ax
,
137 struct axs_value
* value
,
140 char *operand_name
));
141 static void gen_repeat
PARAMS ((union exp_element
** pc
,
142 struct agent_expr
* ax
,
143 struct axs_value
* value
));
144 static void gen_sizeof
PARAMS ((union exp_element
** pc
,
145 struct agent_expr
* ax
,
146 struct axs_value
* value
));
147 static void gen_expr
PARAMS ((union exp_element
** pc
,
148 struct agent_expr
* ax
,
149 struct axs_value
* value
));
151 static void print_axs_value
PARAMS ((GDB_FILE
* f
, struct axs_value
* value
));
152 static void agent_command
PARAMS ((char *exp
, int from_tty
));
155 /* Detecting constant expressions. */
157 /* If the variable reference at *PC is a constant, return its value.
158 Otherwise, return zero.
160 Hey, Wally! How can a variable reference be a constant?
162 Well, Beav, this function really handles the OP_VAR_VALUE operator,
163 not specifically variable references. GDB uses OP_VAR_VALUE to
164 refer to any kind of symbolic reference: function names, enum
165 elements, and goto labels are all handled through the OP_VAR_VALUE
166 operator, even though they're constants. It makes sense given the
169 Gee, Wally, don'cha wonder sometimes if data representations that
170 subvert commonly accepted definitions of terms in favor of heavily
171 context-specific interpretations are really just a tool of the
172 programming hegemony to preserve their power and exclude the
175 static struct value
*
179 struct type
*type
= SYMBOL_TYPE (var
);
181 switch (SYMBOL_CLASS (var
))
184 return value_from_longest (type
, (LONGEST
) SYMBOL_VALUE (var
));
187 return value_from_longest (type
, (LONGEST
) SYMBOL_VALUE_ADDRESS (var
));
195 /* If the expression starting at *PC has a constant value, return it.
196 Otherwise, return zero. If we return a value, then *PC will be
197 advanced to the end of it. If we return zero, *PC could be
199 static struct value
*
201 union exp_element
**pc
;
203 enum exp_opcode op
= (*pc
)->opcode
;
210 struct type
*type
= (*pc
)[1].type
;
211 LONGEST k
= (*pc
)[2].longconst
;
213 return value_from_longest (type
, k
);
218 struct value
*v
= const_var_ref ((*pc
)[2].symbol
);
223 /* We could add more operators in here. */
227 v1
= const_expr (pc
);
229 return value_neg (v1
);
239 /* Like const_expr, but guarantee also that *PC is undisturbed if the
240 expression is not constant. */
241 static struct value
*
242 maybe_const_expr (pc
)
243 union exp_element
**pc
;
245 union exp_element
*tentative_pc
= *pc
;
246 struct value
*v
= const_expr (&tentative_pc
);
248 /* If we got a value, then update the real PC. */
256 /* Generating bytecode from GDB expressions: general assumptions */
258 /* Here are a few general assumptions made throughout the code; if you
259 want to make a change that contradicts one of these, then you'd
260 better scan things pretty thoroughly.
262 - We assume that all values occupy one stack element. For example,
263 sometimes we'll swap to get at the left argument to a binary
264 operator. If we decide that void values should occupy no stack
265 elements, or that synthetic arrays (whose size is determined at
266 run time, created by the `@' operator) should occupy two stack
267 elements (address and length), then this will cause trouble.
269 - We assume the stack elements are infinitely wide, and that we
270 don't have to worry what happens if the user requests an
271 operation that is wider than the actual interpreter's stack.
272 That is, it's up to the interpreter to handle directly all the
273 integer widths the user has access to. (Woe betide the language
276 - We don't support side effects. Thus, we don't have to worry about
277 GCC's generalized lvalues, function calls, etc.
279 - We don't support floating point. Many places where we switch on
280 some type don't bother to include cases for floating point; there
281 may be even more subtle ways this assumption exists. For
282 example, the arguments to % must be integers.
284 - We assume all subexpressions have a static, unchanging type. If
285 we tried to support convenience variables, this would be a
288 - All values on the stack should always be fully zero- or
291 (I wasn't sure whether to choose this or its opposite --- that
292 only addresses are assumed extended --- but it turns out that
293 neither convention completely eliminates spurious extend
294 operations (if everything is always extended, then you have to
295 extend after add, because it could overflow; if nothing is
296 extended, then you end up producing extends whenever you change
297 sizes), and this is simpler.) */
300 /* Generating bytecode from GDB expressions: the `trace' kludge */
302 /* The compiler in this file is a general-purpose mechanism for
303 translating GDB expressions into bytecode. One ought to be able to
304 find a million and one uses for it.
306 However, at the moment it is HOPELESSLY BRAIN-DAMAGED for the sake
307 of expediency. Let he who is without sin cast the first stone.
309 For the data tracing facility, we need to insert `trace' bytecodes
310 before each data fetch; this records all the memory that the
311 expression touches in the course of evaluation, so that memory will
312 be available when the user later tries to evaluate the expression
315 This should be done (I think) in a post-processing pass, that walks
316 an arbitrary agent expression and inserts `trace' operations at the
317 appropriate points. But it's much faster to just hack them
318 directly into the code. And since we're in a crunch, that's what
321 Setting the flag trace_kludge to non-zero enables the code that
322 emits the trace bytecodes at the appropriate points. */
323 static int trace_kludge
;
325 /* Trace the lvalue on the stack, if it needs it. In either case, pop
326 the value. Useful on the left side of a comma, and at the end of
327 an expression being used for tracing. */
329 gen_traced_pop (ax
, value
)
330 struct agent_expr
*ax
;
331 struct axs_value
*value
;
337 /* We don't trace rvalues, just the lvalues necessary to
338 produce them. So just dispose of this value. */
339 ax_simple (ax
, aop_pop
);
342 case axs_lvalue_memory
:
344 int length
= TYPE_LENGTH (value
->type
);
346 /* There's no point in trying to use a trace_quick bytecode
347 here, since "trace_quick SIZE pop" is three bytes, whereas
348 "const8 SIZE trace" is also three bytes, does the same
349 thing, and the simplest code which generates that will also
350 work correctly for objects with large sizes. */
351 ax_const_l (ax
, length
);
352 ax_simple (ax
, aop_trace
);
356 case axs_lvalue_register
:
357 /* We need to mention the register somewhere in the bytecode,
358 so ax_reqs will pick it up and add it to the mask of
360 ax_reg (ax
, value
->u
.reg
);
361 ax_simple (ax
, aop_pop
);
365 /* If we're not tracing, just pop the value. */
366 ax_simple (ax
, aop_pop
);
371 /* Generating bytecode from GDB expressions: helper functions */
373 /* Assume that the lower bits of the top of the stack is a value of
374 type TYPE, and the upper bits are zero. Sign-extend if necessary. */
376 gen_sign_extend (ax
, type
)
377 struct agent_expr
*ax
;
380 /* Do we need to sign-extend this? */
381 if (!TYPE_UNSIGNED (type
))
382 ax_ext (ax
, type
->length
* TARGET_CHAR_BIT
);
386 /* Assume the lower bits of the top of the stack hold a value of type
387 TYPE, and the upper bits are garbage. Sign-extend or truncate as
390 gen_extend (ax
, type
)
391 struct agent_expr
*ax
;
394 int bits
= type
->length
* TARGET_CHAR_BIT
;
396 ((TYPE_UNSIGNED (type
) ? ax_zero_ext
: ax_ext
) (ax
, bits
));
400 /* Assume that the top of the stack contains a value of type "pointer
401 to TYPE"; generate code to fetch its value. Note that TYPE is the
402 target type, not the pointer type. */
405 struct agent_expr
*ax
;
410 /* Record the area of memory we're about to fetch. */
411 ax_trace_quick (ax
, TYPE_LENGTH (type
));
420 /* It's a scalar value, so we know how to dereference it. How
421 many bytes long is it? */
422 switch (type
->length
)
424 case 8 / TARGET_CHAR_BIT
:
425 ax_simple (ax
, aop_ref8
);
427 case 16 / TARGET_CHAR_BIT
:
428 ax_simple (ax
, aop_ref16
);
430 case 32 / TARGET_CHAR_BIT
:
431 ax_simple (ax
, aop_ref32
);
433 case 64 / TARGET_CHAR_BIT
:
434 ax_simple (ax
, aop_ref64
);
437 /* Either our caller shouldn't have asked us to dereference
438 that pointer (other code's fault), or we're not
439 implementing something we should be (this code's fault).
440 In any case, it's a bug the user shouldn't see. */
442 error ("GDB bug: ax-gdb.c (gen_fetch): strange size");
445 gen_sign_extend (ax
, type
);
449 /* Either our caller shouldn't have asked us to dereference that
450 pointer (other code's fault), or we're not implementing
451 something we should be (this code's fault). In any case,
452 it's a bug the user shouldn't see. */
453 error ("GDB bug: ax-gdb.c (gen_fetch): bad type code");
458 /* Generate code to left shift the top of the stack by DISTANCE bits, or
459 right shift it by -DISTANCE bits if DISTANCE < 0. This generates
460 unsigned (logical) right shifts. */
462 gen_left_shift (ax
, distance
)
463 struct agent_expr
*ax
;
468 ax_const_l (ax
, distance
);
469 ax_simple (ax
, aop_lsh
);
471 else if (distance
< 0)
473 ax_const_l (ax
, -distance
);
474 ax_simple (ax
, aop_rsh_unsigned
);
480 /* Generating bytecode from GDB expressions: symbol references */
482 /* Generate code to push the base address of the argument portion of
483 the top stack frame. */
485 gen_frame_args_address (ax
)
486 struct agent_expr
*ax
;
488 long frame_reg
, frame_offset
;
490 TARGET_VIRTUAL_FRAME_POINTER (ax
->scope
, &frame_reg
, &frame_offset
);
491 ax_reg (ax
, frame_reg
);
492 gen_offset (ax
, frame_offset
);
496 /* Generate code to push the base address of the locals portion of the
499 gen_frame_locals_address (ax
)
500 struct agent_expr
*ax
;
502 long frame_reg
, frame_offset
;
504 TARGET_VIRTUAL_FRAME_POINTER (ax
->scope
, &frame_reg
, &frame_offset
);
505 ax_reg (ax
, frame_reg
);
506 gen_offset (ax
, frame_offset
);
510 /* Generate code to add OFFSET to the top of the stack. Try to
511 generate short and readable code. We use this for getting to
512 variables on the stack, and structure members. If we were
513 programming in ML, it would be clearer why these are the same
516 gen_offset (ax
, offset
)
517 struct agent_expr
*ax
;
520 /* It would suffice to simply push the offset and add it, but this
521 makes it easier to read positive and negative offsets in the
525 ax_const_l (ax
, offset
);
526 ax_simple (ax
, aop_add
);
530 ax_const_l (ax
, -offset
);
531 ax_simple (ax
, aop_sub
);
536 /* In many cases, a symbol's value is the offset from some other
537 address (stack frame, base register, etc.) Generate code to add
538 VAR's value to the top of the stack. */
540 gen_sym_offset (ax
, var
)
541 struct agent_expr
*ax
;
544 gen_offset (ax
, SYMBOL_VALUE (var
));
548 /* Generate code for a variable reference to AX. The variable is the
549 symbol VAR. Set VALUE to describe the result. */
552 gen_var_ref (ax
, value
, var
)
553 struct agent_expr
*ax
;
554 struct axs_value
*value
;
557 /* Dereference any typedefs. */
558 value
->type
= check_typedef (SYMBOL_TYPE (var
));
560 /* I'm imitating the code in read_var_value. */
561 switch (SYMBOL_CLASS (var
))
563 case LOC_CONST
: /* A constant, like an enum value. */
564 ax_const_l (ax
, (LONGEST
) SYMBOL_VALUE (var
));
565 value
->kind
= axs_rvalue
;
568 case LOC_LABEL
: /* A goto label, being used as a value. */
569 ax_const_l (ax
, (LONGEST
) SYMBOL_VALUE_ADDRESS (var
));
570 value
->kind
= axs_rvalue
;
573 case LOC_CONST_BYTES
:
574 error ("GDB bug: ax-gdb.c (gen_var_ref): LOC_CONST_BYTES symbols are not supported");
576 /* Variable at a fixed location in memory. Easy. */
578 /* Push the address of the variable. */
579 ax_const_l (ax
, SYMBOL_VALUE_ADDRESS (var
));
580 value
->kind
= axs_lvalue_memory
;
583 case LOC_ARG
: /* var lives in argument area of frame */
584 gen_frame_args_address (ax
);
585 gen_sym_offset (ax
, var
);
586 value
->kind
= axs_lvalue_memory
;
589 case LOC_REF_ARG
: /* As above, but the frame slot really
590 holds the address of the variable. */
591 gen_frame_args_address (ax
);
592 gen_sym_offset (ax
, var
);
593 /* Don't assume any particular pointer size. */
594 gen_fetch (ax
, lookup_pointer_type (builtin_type_void
));
595 value
->kind
= axs_lvalue_memory
;
598 case LOC_LOCAL
: /* var lives in locals area of frame */
600 gen_frame_locals_address (ax
);
601 gen_sym_offset (ax
, var
);
602 value
->kind
= axs_lvalue_memory
;
605 case LOC_BASEREG
: /* relative to some base register */
606 case LOC_BASEREG_ARG
:
607 ax_reg (ax
, SYMBOL_BASEREG (var
));
608 gen_sym_offset (ax
, var
);
609 value
->kind
= axs_lvalue_memory
;
613 error ("Cannot compute value of typedef `%s'.",
614 SYMBOL_SOURCE_NAME (var
));
618 ax_const_l (ax
, BLOCK_START (SYMBOL_BLOCK_VALUE (var
)));
619 value
->kind
= axs_rvalue
;
624 /* Don't generate any code at all; in the process of treating
625 this as an lvalue or rvalue, the caller will generate the
627 value
->kind
= axs_lvalue_register
;
628 value
->u
.reg
= SYMBOL_VALUE (var
);
631 /* A lot like LOC_REF_ARG, but the pointer lives directly in a
632 register, not on the stack. Simpler than LOC_REGISTER and
633 LOC_REGPARM, because it's just like any other case where the
634 thing has a real address. */
635 case LOC_REGPARM_ADDR
:
636 ax_reg (ax
, SYMBOL_VALUE (var
));
637 value
->kind
= axs_lvalue_memory
;
642 struct minimal_symbol
*msym
643 = lookup_minimal_symbol (SYMBOL_NAME (var
), NULL
, NULL
);
645 error ("Couldn't resolve symbol `%s'.", SYMBOL_SOURCE_NAME (var
));
647 /* Push the address of the variable. */
648 ax_const_l (ax
, SYMBOL_VALUE_ADDRESS (msym
));
649 value
->kind
= axs_lvalue_memory
;
653 case LOC_OPTIMIZED_OUT
:
654 error ("The variable `%s' has been optimized out.",
655 SYMBOL_SOURCE_NAME (var
));
659 error ("Cannot find value of botched symbol `%s'.",
660 SYMBOL_SOURCE_NAME (var
));
667 /* Generating bytecode from GDB expressions: literals */
670 gen_int_literal (ax
, value
, k
, type
)
671 struct agent_expr
*ax
;
672 struct axs_value
*value
;
677 value
->kind
= axs_rvalue
;
683 /* Generating bytecode from GDB expressions: unary conversions, casts */
685 /* Take what's on the top of the stack (as described by VALUE), and
686 try to make an rvalue out of it. Signal an error if we can't do
689 require_rvalue (ax
, value
)
690 struct agent_expr
*ax
;
691 struct axs_value
*value
;
696 /* It's already an rvalue. */
699 case axs_lvalue_memory
:
700 /* The top of stack is the address of the object. Dereference. */
701 gen_fetch (ax
, value
->type
);
704 case axs_lvalue_register
:
705 /* There's nothing on the stack, but value->u.reg is the
706 register number containing the value.
708 When we add floating-point support, this is going to have to
709 change. What about SPARC register pairs, for example? */
710 ax_reg (ax
, value
->u
.reg
);
711 gen_extend (ax
, value
->type
);
715 value
->kind
= axs_rvalue
;
719 /* Assume the top of the stack is described by VALUE, and perform the
720 usual unary conversions. This is motivated by ANSI 6.2.2, but of
721 course GDB expressions are not ANSI; they're the mishmash union of
722 a bunch of languages. Rah.
724 NOTE! This function promises to produce an rvalue only when the
725 incoming value is of an appropriate type. In other words, the
726 consumer of the value this function produces may assume the value
727 is an rvalue only after checking its type.
729 The immediate issue is that if the user tries to use a structure or
730 union as an operand of, say, the `+' operator, we don't want to try
731 to convert that structure to an rvalue; require_rvalue will bomb on
732 structs and unions. Rather, we want to simply pass the struct
733 lvalue through unchanged, and let `+' raise an error. */
736 gen_usual_unary (ax
, value
)
737 struct agent_expr
*ax
;
738 struct axs_value
*value
;
740 /* We don't have to generate any code for the usual integral
741 conversions, since values are always represented as full-width on
742 the stack. Should we tweak the type? */
744 /* Some types require special handling. */
745 switch (value
->type
->code
)
747 /* Functions get converted to a pointer to the function. */
749 value
->type
= lookup_pointer_type (value
->type
);
750 value
->kind
= axs_rvalue
; /* Should always be true, but just in case. */
753 /* Arrays get converted to a pointer to their first element, and
754 are no longer an lvalue. */
755 case TYPE_CODE_ARRAY
:
757 struct type
*elements
= TYPE_TARGET_TYPE (value
->type
);
758 value
->type
= lookup_pointer_type (elements
);
759 value
->kind
= axs_rvalue
;
760 /* We don't need to generate any code; the address of the array
761 is also the address of its first element. */
765 /* Don't try to convert structures and unions to rvalues. Let the
766 consumer signal an error. */
767 case TYPE_CODE_STRUCT
:
768 case TYPE_CODE_UNION
:
771 /* If the value is an enum, call it an integer. */
773 value
->type
= builtin_type_int
;
777 /* If the value is an lvalue, dereference it. */
778 require_rvalue (ax
, value
);
782 /* Return non-zero iff the type TYPE1 is considered "wider" than the
783 type TYPE2, according to the rules described in gen_usual_arithmetic. */
785 type_wider_than (type1
, type2
)
786 struct type
*type1
, *type2
;
788 return (TYPE_LENGTH (type1
) > TYPE_LENGTH (type2
)
789 || (TYPE_LENGTH (type1
) == TYPE_LENGTH (type2
)
790 && TYPE_UNSIGNED (type1
)
791 && !TYPE_UNSIGNED (type2
)));
795 /* Return the "wider" of the two types TYPE1 and TYPE2. */
797 max_type (type1
, type2
)
798 struct type
*type1
, *type2
;
800 return type_wider_than (type1
, type2
) ? type1
: type2
;
804 /* Generate code to convert a scalar value of type FROM to type TO. */
806 gen_conversion (ax
, from
, to
)
807 struct agent_expr
*ax
;
808 struct type
*from
, *to
;
810 /* Perhaps there is a more graceful way to state these rules. */
812 /* If we're converting to a narrower type, then we need to clear out
814 if (TYPE_LENGTH (to
) < TYPE_LENGTH (from
))
815 gen_extend (ax
, from
);
817 /* If the two values have equal width, but different signednesses,
818 then we need to extend. */
819 else if (TYPE_LENGTH (to
) == TYPE_LENGTH (from
))
821 if (TYPE_UNSIGNED (from
) != TYPE_UNSIGNED (to
))
825 /* If we're converting to a wider type, and becoming unsigned, then
826 we need to zero out any possible sign bits. */
827 else if (TYPE_LENGTH (to
) > TYPE_LENGTH (from
))
829 if (TYPE_UNSIGNED (to
))
835 /* Return non-zero iff the type FROM will require any bytecodes to be
836 emitted to be converted to the type TO. */
838 is_nontrivial_conversion (from
, to
)
839 struct type
*from
, *to
;
841 struct agent_expr
*ax
= new_agent_expr (0);
844 /* Actually generate the code, and see if anything came out. At the
845 moment, it would be trivial to replicate the code in
846 gen_conversion here, but in the future, when we're supporting
847 floating point and the like, it may not be. Doing things this
848 way allows this function to be independent of the logic in
850 gen_conversion (ax
, from
, to
);
851 nontrivial
= ax
->len
> 0;
852 free_agent_expr (ax
);
857 /* Generate code to perform the "usual arithmetic conversions" (ANSI C
858 6.2.1.5) for the two operands of an arithmetic operator. This
859 effectively finds a "least upper bound" type for the two arguments,
860 and promotes each argument to that type. *VALUE1 and *VALUE2
861 describe the values as they are passed in, and as they are left. */
863 gen_usual_arithmetic (ax
, value1
, value2
)
864 struct agent_expr
*ax
;
865 struct axs_value
*value1
, *value2
;
867 /* Do the usual binary conversions. */
868 if (TYPE_CODE (value1
->type
) == TYPE_CODE_INT
869 && TYPE_CODE (value2
->type
) == TYPE_CODE_INT
)
871 /* The ANSI integral promotions seem to work this way: Order the
872 integer types by size, and then by signedness: an n-bit
873 unsigned type is considered "wider" than an n-bit signed
874 type. Promote to the "wider" of the two types, and always
875 promote at least to int. */
876 struct type
*target
= max_type (builtin_type_int
,
877 max_type (value1
->type
, value2
->type
));
879 /* Deal with value2, on the top of the stack. */
880 gen_conversion (ax
, value2
->type
, target
);
882 /* Deal with value1, not on the top of the stack. Don't
883 generate the `swap' instructions if we're not actually going
885 if (is_nontrivial_conversion (value1
->type
, target
))
887 ax_simple (ax
, aop_swap
);
888 gen_conversion (ax
, value1
->type
, target
);
889 ax_simple (ax
, aop_swap
);
892 value1
->type
= value2
->type
= target
;
897 /* Generate code to perform the integral promotions (ANSI 6.2.1.1) on
898 the value on the top of the stack, as described by VALUE. Assume
899 the value has integral type. */
901 gen_integral_promotions (ax
, value
)
902 struct agent_expr
*ax
;
903 struct axs_value
*value
;
905 if (!type_wider_than (value
->type
, builtin_type_int
))
907 gen_conversion (ax
, value
->type
, builtin_type_int
);
908 value
->type
= builtin_type_int
;
910 else if (!type_wider_than (value
->type
, builtin_type_unsigned_int
))
912 gen_conversion (ax
, value
->type
, builtin_type_unsigned_int
);
913 value
->type
= builtin_type_unsigned_int
;
918 /* Generate code for a cast to TYPE. */
920 gen_cast (ax
, value
, type
)
921 struct agent_expr
*ax
;
922 struct axs_value
*value
;
925 /* GCC does allow casts to yield lvalues, so this should be fixed
926 before merging these changes into the trunk. */
927 require_rvalue (ax
, value
);
928 /* Dereference typedefs. */
929 type
= check_typedef (type
);
934 /* It's implementation-defined, and I'll bet this is what GCC
938 case TYPE_CODE_ARRAY
:
939 case TYPE_CODE_STRUCT
:
940 case TYPE_CODE_UNION
:
942 error ("Illegal type cast: intended type must be scalar.");
945 /* We don't have to worry about the size of the value, because
946 all our integral values are fully sign-extended, and when
947 casting pointers we can do anything we like. Is there any
948 way for us to actually know what GCC actually does with a
954 gen_conversion (ax
, value
->type
, type
);
958 /* We could pop the value, and rely on everyone else to check
959 the type and notice that this value doesn't occupy a stack
960 slot. But for now, leave the value on the stack, and
961 preserve the "value == stack element" assumption. */
965 error ("Casts to requested type are not yet implemented.");
973 /* Generating bytecode from GDB expressions: arithmetic */
975 /* Scale the integer on the top of the stack by the size of the target
976 of the pointer type TYPE. */
978 gen_scale (ax
, op
, type
)
979 struct agent_expr
*ax
;
983 struct type
*element
= TYPE_TARGET_TYPE (type
);
985 if (element
->length
!= 1)
987 ax_const_l (ax
, element
->length
);
993 /* Generate code for an addition; non-trivial because we deal with
994 pointer arithmetic. We set VALUE to describe the result value; we
995 assume VALUE1 and VALUE2 describe the two operands, and that
996 they've undergone the usual binary conversions. Used by both
997 BINOP_ADD and BINOP_SUBSCRIPT. NAME is used in error messages. */
999 gen_add (ax
, value
, value1
, value2
, name
)
1000 struct agent_expr
*ax
;
1001 struct axs_value
*value
, *value1
, *value2
;
1004 /* Is it INT+PTR? */
1005 if (value1
->type
->code
== TYPE_CODE_INT
1006 && value2
->type
->code
== TYPE_CODE_PTR
)
1008 /* Swap the values and proceed normally. */
1009 ax_simple (ax
, aop_swap
);
1010 gen_scale (ax
, aop_mul
, value2
->type
);
1011 ax_simple (ax
, aop_add
);
1012 gen_extend (ax
, value2
->type
); /* Catch overflow. */
1013 value
->type
= value2
->type
;
1016 /* Is it PTR+INT? */
1017 else if (value1
->type
->code
== TYPE_CODE_PTR
1018 && value2
->type
->code
== TYPE_CODE_INT
)
1020 gen_scale (ax
, aop_mul
, value1
->type
);
1021 ax_simple (ax
, aop_add
);
1022 gen_extend (ax
, value1
->type
); /* Catch overflow. */
1023 value
->type
= value1
->type
;
1026 /* Must be number + number; the usual binary conversions will have
1027 brought them both to the same width. */
1028 else if (value1
->type
->code
== TYPE_CODE_INT
1029 && value2
->type
->code
== TYPE_CODE_INT
)
1031 ax_simple (ax
, aop_add
);
1032 gen_extend (ax
, value1
->type
); /* Catch overflow. */
1033 value
->type
= value1
->type
;
1037 error ("Illegal combination of types in %s.", name
);
1039 value
->kind
= axs_rvalue
;
1043 /* Generate code for an addition; non-trivial because we have to deal
1044 with pointer arithmetic. We set VALUE to describe the result
1045 value; we assume VALUE1 and VALUE2 describe the two operands, and
1046 that they've undergone the usual binary conversions. */
1048 gen_sub (ax
, value
, value1
, value2
)
1049 struct agent_expr
*ax
;
1050 struct axs_value
*value
, *value1
, *value2
;
1052 if (value1
->type
->code
== TYPE_CODE_PTR
)
1054 /* Is it PTR - INT? */
1055 if (value2
->type
->code
== TYPE_CODE_INT
)
1057 gen_scale (ax
, aop_mul
, value1
->type
);
1058 ax_simple (ax
, aop_sub
);
1059 gen_extend (ax
, value1
->type
); /* Catch overflow. */
1060 value
->type
= value1
->type
;
1063 /* Is it PTR - PTR? Strictly speaking, the types ought to
1064 match, but this is what the normal GDB expression evaluator
1066 else if (value2
->type
->code
== TYPE_CODE_PTR
1067 && (TYPE_LENGTH (TYPE_TARGET_TYPE (value1
->type
))
1068 == TYPE_LENGTH (TYPE_TARGET_TYPE (value2
->type
))))
1070 ax_simple (ax
, aop_sub
);
1071 gen_scale (ax
, aop_div_unsigned
, value1
->type
);
1072 value
->type
= builtin_type_long
; /* FIXME --- should be ptrdiff_t */
1076 First argument of `-' is a pointer, but second argument is neither\n\
1077 an integer nor a pointer of the same type.");
1080 /* Must be number + number. */
1081 else if (value1
->type
->code
== TYPE_CODE_INT
1082 && value2
->type
->code
== TYPE_CODE_INT
)
1084 ax_simple (ax
, aop_sub
);
1085 gen_extend (ax
, value1
->type
); /* Catch overflow. */
1086 value
->type
= value1
->type
;
1090 error ("Illegal combination of types in subtraction.");
1092 value
->kind
= axs_rvalue
;
1095 /* Generate code for a binary operator that doesn't do pointer magic.
1096 We set VALUE to describe the result value; we assume VALUE1 and
1097 VALUE2 describe the two operands, and that they've undergone the
1098 usual binary conversions. MAY_CARRY should be non-zero iff the
1099 result needs to be extended. NAME is the English name of the
1100 operator, used in error messages */
1102 gen_binop (ax
, value
, value1
, value2
, op
, op_unsigned
, may_carry
, name
)
1103 struct agent_expr
*ax
;
1104 struct axs_value
*value
, *value1
, *value2
;
1105 enum agent_op op
, op_unsigned
;
1109 /* We only handle INT op INT. */
1110 if ((value1
->type
->code
!= TYPE_CODE_INT
)
1111 || (value2
->type
->code
!= TYPE_CODE_INT
))
1112 error ("Illegal combination of types in %s.", name
);
1115 TYPE_UNSIGNED (value1
->type
) ? op_unsigned
: op
);
1117 gen_extend (ax
, value1
->type
); /* catch overflow */
1118 value
->type
= value1
->type
;
1119 value
->kind
= axs_rvalue
;
1124 gen_logical_not (ax
, value
)
1125 struct agent_expr
*ax
;
1126 struct axs_value
*value
;
1128 if (TYPE_CODE (value
->type
) != TYPE_CODE_INT
1129 && TYPE_CODE (value
->type
) != TYPE_CODE_PTR
)
1130 error ("Illegal type of operand to `!'.");
1132 gen_usual_unary (ax
, value
);
1133 ax_simple (ax
, aop_log_not
);
1134 value
->type
= builtin_type_int
;
1139 gen_complement (ax
, value
)
1140 struct agent_expr
*ax
;
1141 struct axs_value
*value
;
1143 if (TYPE_CODE (value
->type
) != TYPE_CODE_INT
)
1144 error ("Illegal type of operand to `~'.");
1146 gen_usual_unary (ax
, value
);
1147 gen_integral_promotions (ax
, value
);
1148 ax_simple (ax
, aop_bit_not
);
1149 gen_extend (ax
, value
->type
);
1154 /* Generating bytecode from GDB expressions: * & . -> @ sizeof */
1156 /* Dereference the value on the top of the stack. */
1158 gen_deref (ax
, value
)
1159 struct agent_expr
*ax
;
1160 struct axs_value
*value
;
1162 /* The caller should check the type, because several operators use
1163 this, and we don't know what error message to generate. */
1164 if (value
->type
->code
!= TYPE_CODE_PTR
)
1165 error ("GDB bug: ax-gdb.c (gen_deref): expected a pointer");
1167 /* We've got an rvalue now, which is a pointer. We want to yield an
1168 lvalue, whose address is exactly that pointer. So we don't
1169 actually emit any code; we just change the type from "Pointer to
1170 T" to "T", and mark the value as an lvalue in memory. Leave it
1171 to the consumer to actually dereference it. */
1172 value
->type
= check_typedef (TYPE_TARGET_TYPE (value
->type
));
1173 value
->kind
= ((value
->type
->code
== TYPE_CODE_FUNC
)
1174 ? axs_rvalue
: axs_lvalue_memory
);
1178 /* Produce the address of the lvalue on the top of the stack. */
1180 gen_address_of (ax
, value
)
1181 struct agent_expr
*ax
;
1182 struct axs_value
*value
;
1184 /* Special case for taking the address of a function. The ANSI
1185 standard describes this as a special case, too, so this
1186 arrangement is not without motivation. */
1187 if (value
->type
->code
== TYPE_CODE_FUNC
)
1188 /* The value's already an rvalue on the stack, so we just need to
1190 value
->type
= lookup_pointer_type (value
->type
);
1192 switch (value
->kind
)
1195 error ("Operand of `&' is an rvalue, which has no address.");
1197 case axs_lvalue_register
:
1198 error ("Operand of `&' is in a register, and has no address.");
1200 case axs_lvalue_memory
:
1201 value
->kind
= axs_rvalue
;
1202 value
->type
= lookup_pointer_type (value
->type
);
1208 /* A lot of this stuff will have to change to support C++. But we're
1209 not going to deal with that at the moment. */
1211 /* Find the field in the structure type TYPE named NAME, and return
1212 its index in TYPE's field array. */
1214 find_field (type
, name
)
1220 CHECK_TYPEDEF (type
);
1222 /* Make sure this isn't C++. */
1223 if (TYPE_N_BASECLASSES (type
) != 0)
1224 error ("GDB bug: ax-gdb.c (find_field): derived classes supported");
1226 for (i
= 0; i
< TYPE_NFIELDS (type
); i
++)
1228 char *this_name
= TYPE_FIELD_NAME (type
, i
);
1230 if (this_name
&& STREQ (name
, this_name
))
1233 if (this_name
[0] == '\0')
1234 error ("GDB bug: ax-gdb.c (find_field): anonymous unions not supported");
1237 error ("Couldn't find member named `%s' in struct/union `%s'",
1238 name
, type
->tag_name
);
1244 /* Generate code to push the value of a bitfield of a structure whose
1245 address is on the top of the stack. START and END give the
1246 starting and one-past-ending *bit* numbers of the field within the
1249 gen_bitfield_ref (ax
, value
, type
, start
, end
)
1250 struct agent_expr
*ax
;
1251 struct axs_value
*value
;
1255 /* Note that ops[i] fetches 8 << i bits. */
1256 static enum agent_op ops
[]
1258 {aop_ref8
, aop_ref16
, aop_ref32
, aop_ref64
};
1259 static int num_ops
= (sizeof (ops
) / sizeof (ops
[0]));
1261 /* We don't want to touch any byte that the bitfield doesn't
1262 actually occupy; we shouldn't make any accesses we're not
1263 explicitly permitted to. We rely here on the fact that the
1264 bytecode `ref' operators work on unaligned addresses.
1266 It takes some fancy footwork to get the stack to work the way
1267 we'd like. Say we're retrieving a bitfield that requires three
1268 fetches. Initially, the stack just contains the address:
1270 For the first fetch, we duplicate the address
1272 then add the byte offset, do the fetch, and shift and mask as
1273 needed, yielding a fragment of the value, properly aligned for
1274 the final bitwise or:
1276 then we swap, and repeat the process:
1277 frag1 addr --- address on top
1278 frag1 addr addr --- duplicate it
1279 frag1 addr frag2 --- get second fragment
1280 frag1 frag2 addr --- swap again
1281 frag1 frag2 frag3 --- get third fragment
1282 Notice that, since the third fragment is the last one, we don't
1283 bother duplicating the address this time. Now we have all the
1284 fragments on the stack, and we can simply `or' them together,
1285 yielding the final value of the bitfield. */
1287 /* The first and one-after-last bits in the field, but rounded down
1288 and up to byte boundaries. */
1289 int bound_start
= (start
/ TARGET_CHAR_BIT
) * TARGET_CHAR_BIT
;
1290 int bound_end
= (((end
+ TARGET_CHAR_BIT
- 1)
1294 /* current bit offset within the structure */
1297 /* The index in ops of the opcode we're considering. */
1300 /* The number of fragments we generated in the process. Probably
1301 equal to the number of `one' bits in bytesize, but who cares? */
1304 /* Dereference any typedefs. */
1305 type
= check_typedef (type
);
1307 /* Can we fetch the number of bits requested at all? */
1308 if ((end
- start
) > ((1 << num_ops
) * 8))
1309 error ("GDB bug: ax-gdb.c (gen_bitfield_ref): bitfield too wide");
1311 /* Note that we know here that we only need to try each opcode once.
1312 That may not be true on machines with weird byte sizes. */
1313 offset
= bound_start
;
1315 for (op
= num_ops
- 1; op
>= 0; op
--)
1317 /* number of bits that ops[op] would fetch */
1318 int op_size
= 8 << op
;
1320 /* The stack at this point, from bottom to top, contains zero or
1321 more fragments, then the address. */
1323 /* Does this fetch fit within the bitfield? */
1324 if (offset
+ op_size
<= bound_end
)
1326 /* Is this the last fragment? */
1327 int last_frag
= (offset
+ op_size
== bound_end
);
1330 ax_simple (ax
, aop_dup
); /* keep a copy of the address */
1332 /* Add the offset. */
1333 gen_offset (ax
, offset
/ TARGET_CHAR_BIT
);
1337 /* Record the area of memory we're about to fetch. */
1338 ax_trace_quick (ax
, op_size
/ TARGET_CHAR_BIT
);
1341 /* Perform the fetch. */
1342 ax_simple (ax
, ops
[op
]);
1344 /* Shift the bits we have to their proper position.
1345 gen_left_shift will generate right shifts when the operand
1348 A big-endian field diagram to ponder:
1349 byte 0 byte 1 byte 2 byte 3 byte 4 byte 5 byte 6 byte 7
1350 +------++------++------++------++------++------++------++------+
1351 xxxxAAAAAAAAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBCCCCCxxxxxxxxxxx
1353 bit number 16 32 48 53
1354 These are bit numbers as supplied by GDB. Note that the
1355 bit numbers run from right to left once you've fetched the
1358 A little-endian field diagram to ponder:
1359 byte 7 byte 6 byte 5 byte 4 byte 3 byte 2 byte 1 byte 0
1360 +------++------++------++------++------++------++------++------+
1361 xxxxxxxxxxxAAAAABBBBBBBBBBBBBBBBCCCCCCCCCCCCCCCCCCCCCCCCCCCCxxxx
1363 bit number 48 32 16 4 0
1365 In both cases, the most significant end is on the left
1366 (i.e. normal numeric writing order), which means that you
1367 don't go crazy thinking about `left' and `right' shifts.
1369 We don't have to worry about masking yet:
1370 - If they contain garbage off the least significant end, then we
1371 must be looking at the low end of the field, and the right
1372 shift will wipe them out.
1373 - If they contain garbage off the most significant end, then we
1374 must be looking at the most significant end of the word, and
1375 the sign/zero extension will wipe them out.
1376 - If we're in the interior of the word, then there is no garbage
1377 on either end, because the ref operators zero-extend. */
1378 if (TARGET_BYTE_ORDER
== BIG_ENDIAN
)
1379 gen_left_shift (ax
, end
- (offset
+ op_size
));
1381 gen_left_shift (ax
, offset
- start
);
1384 /* Bring the copy of the address up to the top. */
1385 ax_simple (ax
, aop_swap
);
1392 /* Generate enough bitwise `or' operations to combine all the
1393 fragments we left on the stack. */
1394 while (fragment_count
-- > 1)
1395 ax_simple (ax
, aop_bit_or
);
1397 /* Sign- or zero-extend the value as appropriate. */
1398 ((TYPE_UNSIGNED (type
) ? ax_zero_ext
: ax_ext
) (ax
, end
- start
));
1400 /* This is *not* an lvalue. Ugh. */
1401 value
->kind
= axs_rvalue
;
1406 /* Generate code to reference the member named FIELD of a structure or
1407 union. The top of the stack, as described by VALUE, should have
1408 type (pointer to a)* struct/union. OPERATOR_NAME is the name of
1409 the operator being compiled, and OPERAND_NAME is the kind of thing
1410 it operates on; we use them in error messages. */
1412 gen_struct_ref (ax
, value
, field
, operator_name
, operand_name
)
1413 struct agent_expr
*ax
;
1414 struct axs_value
*value
;
1416 char *operator_name
;
1422 /* Follow pointers until we reach a non-pointer. These aren't the C
1423 semantics, but they're what the normal GDB evaluator does, so we
1424 should at least be consistent. */
1425 while (value
->type
->code
== TYPE_CODE_PTR
)
1427 gen_usual_unary (ax
, value
);
1428 gen_deref (ax
, value
);
1432 /* This must yield a structure or a union. */
1433 if (TYPE_CODE (type
) != TYPE_CODE_STRUCT
1434 && TYPE_CODE (type
) != TYPE_CODE_UNION
)
1435 error ("The left operand of `%s' is not a %s.",
1436 operator_name
, operand_name
);
1438 /* And it must be in memory; we don't deal with structure rvalues,
1439 or structures living in registers. */
1440 if (value
->kind
!= axs_lvalue_memory
)
1441 error ("Structure does not live in memory.");
1443 i
= find_field (type
, field
);
1445 /* Is this a bitfield? */
1446 if (TYPE_FIELD_PACKED (type
, i
))
1447 gen_bitfield_ref (ax
, value
, TYPE_FIELD_TYPE (type
, i
),
1448 TYPE_FIELD_BITPOS (type
, i
),
1449 (TYPE_FIELD_BITPOS (type
, i
)
1450 + TYPE_FIELD_BITSIZE (type
, i
)));
1453 gen_offset (ax
, TYPE_FIELD_BITPOS (type
, i
) / TARGET_CHAR_BIT
);
1454 value
->kind
= axs_lvalue_memory
;
1455 value
->type
= TYPE_FIELD_TYPE (type
, i
);
1460 /* Generate code for GDB's magical `repeat' operator.
1461 LVALUE @ INT creates an array INT elements long, and whose elements
1462 have the same type as LVALUE, located in memory so that LVALUE is
1463 its first element. For example, argv[0]@argc gives you the array
1464 of command-line arguments.
1466 Unfortunately, because we have to know the types before we actually
1467 have a value for the expression, we can't implement this perfectly
1468 without changing the type system, having values that occupy two
1469 stack slots, doing weird things with sizeof, etc. So we require
1470 the right operand to be a constant expression. */
1472 gen_repeat (pc
, ax
, value
)
1473 union exp_element
**pc
;
1474 struct agent_expr
*ax
;
1475 struct axs_value
*value
;
1477 struct axs_value value1
;
1478 /* We don't want to turn this into an rvalue, so no conversions
1480 gen_expr (pc
, ax
, &value1
);
1481 if (value1
.kind
!= axs_lvalue_memory
)
1482 error ("Left operand of `@' must be an object in memory.");
1484 /* Evaluate the length; it had better be a constant. */
1486 struct value
*v
= const_expr (pc
);
1490 error ("Right operand of `@' must be a constant, in agent expressions.");
1491 if (v
->type
->code
!= TYPE_CODE_INT
)
1492 error ("Right operand of `@' must be an integer.");
1493 length
= value_as_long (v
);
1495 error ("Right operand of `@' must be positive.");
1497 /* The top of the stack is already the address of the object, so
1498 all we need to do is frob the type of the lvalue. */
1500 /* FIXME-type-allocation: need a way to free this type when we are
1503 = create_range_type (0, builtin_type_int
, 0, length
- 1);
1504 struct type
*array
= create_array_type (0, value1
.type
, range
);
1506 value
->kind
= axs_lvalue_memory
;
1507 value
->type
= array
;
1513 /* Emit code for the `sizeof' operator.
1514 *PC should point at the start of the operand expression; we advance it
1515 to the first instruction after the operand. */
1517 gen_sizeof (pc
, ax
, value
)
1518 union exp_element
**pc
;
1519 struct agent_expr
*ax
;
1520 struct axs_value
*value
;
1522 /* We don't care about the value of the operand expression; we only
1523 care about its type. However, in the current arrangement, the
1524 only way to find an expression's type is to generate code for it.
1525 So we generate code for the operand, and then throw it away,
1526 replacing it with code that simply pushes its size. */
1527 int start
= ax
->len
;
1528 gen_expr (pc
, ax
, value
);
1530 /* Throw away the code we just generated. */
1533 ax_const_l (ax
, TYPE_LENGTH (value
->type
));
1534 value
->kind
= axs_rvalue
;
1535 value
->type
= builtin_type_int
;
1539 /* Generating bytecode from GDB expressions: general recursive thingy */
1541 /* A gen_expr function written by a Gen-X'er guy.
1542 Append code for the subexpression of EXPR starting at *POS_P to AX. */
1544 gen_expr (pc
, ax
, value
)
1545 union exp_element
**pc
;
1546 struct agent_expr
*ax
;
1547 struct axs_value
*value
;
1549 /* Used to hold the descriptions of operand expressions. */
1550 struct axs_value value1
, value2
;
1551 enum exp_opcode op
= (*pc
)[0].opcode
;
1553 /* If we're looking at a constant expression, just push its value. */
1555 struct value
*v
= maybe_const_expr (pc
);
1559 ax_const_l (ax
, value_as_long (v
));
1560 value
->kind
= axs_rvalue
;
1561 value
->type
= check_typedef (VALUE_TYPE (v
));
1566 /* Otherwise, go ahead and generate code for it. */
1569 /* Binary arithmetic operators. */
1575 case BINOP_SUBSCRIPT
:
1576 case BINOP_BITWISE_AND
:
1577 case BINOP_BITWISE_IOR
:
1578 case BINOP_BITWISE_XOR
:
1580 gen_expr (pc
, ax
, &value1
);
1581 gen_usual_unary (ax
, &value1
);
1582 gen_expr (pc
, ax
, &value2
);
1583 gen_usual_unary (ax
, &value2
);
1584 gen_usual_arithmetic (ax
, &value1
, &value2
);
1588 gen_add (ax
, value
, &value1
, &value2
, "addition");
1591 gen_sub (ax
, value
, &value1
, &value2
);
1594 gen_binop (ax
, value
, &value1
, &value2
,
1595 aop_mul
, aop_mul
, 1, "multiplication");
1598 gen_binop (ax
, value
, &value1
, &value2
,
1599 aop_div_signed
, aop_div_unsigned
, 1, "division");
1602 gen_binop (ax
, value
, &value1
, &value2
,
1603 aop_rem_signed
, aop_rem_unsigned
, 1, "remainder");
1605 case BINOP_SUBSCRIPT
:
1606 gen_add (ax
, value
, &value1
, &value2
, "array subscripting");
1607 if (TYPE_CODE (value
->type
) != TYPE_CODE_PTR
)
1608 error ("Illegal combination of types in array subscripting.");
1609 gen_deref (ax
, value
);
1611 case BINOP_BITWISE_AND
:
1612 gen_binop (ax
, value
, &value1
, &value2
,
1613 aop_bit_and
, aop_bit_and
, 0, "bitwise and");
1616 case BINOP_BITWISE_IOR
:
1617 gen_binop (ax
, value
, &value1
, &value2
,
1618 aop_bit_or
, aop_bit_or
, 0, "bitwise or");
1621 case BINOP_BITWISE_XOR
:
1622 gen_binop (ax
, value
, &value1
, &value2
,
1623 aop_bit_xor
, aop_bit_xor
, 0, "bitwise exclusive-or");
1627 /* We should only list operators in the outer case statement
1628 that we actually handle in the inner case statement. */
1629 error ("GDB bug: ax-gdb.c (gen_expr): op case sets don't match");
1633 /* Note that we need to be a little subtle about generating code
1634 for comma. In C, we can do some optimizations here because
1635 we know the left operand is only being evaluated for effect.
1636 However, if the tracing kludge is in effect, then we always
1637 need to evaluate the left hand side fully, so that all the
1638 variables it mentions get traced. */
1641 gen_expr (pc
, ax
, &value1
);
1642 /* Don't just dispose of the left operand. We might be tracing,
1643 in which case we want to emit code to trace it if it's an
1645 gen_traced_pop (ax
, &value1
);
1646 gen_expr (pc
, ax
, value
);
1647 /* It's the consumer's responsibility to trace the right operand. */
1650 case OP_LONG
: /* some integer constant */
1652 struct type
*type
= (*pc
)[1].type
;
1653 LONGEST k
= (*pc
)[2].longconst
;
1655 gen_int_literal (ax
, value
, k
, type
);
1660 gen_var_ref (ax
, value
, (*pc
)[2].symbol
);
1666 int reg
= (int) (*pc
)[1].longconst
;
1668 value
->kind
= axs_lvalue_register
;
1670 value
->type
= REGISTER_VIRTUAL_TYPE (reg
);
1674 case OP_INTERNALVAR
:
1675 error ("GDB agent expressions cannot use convenience variables.");
1677 /* Weirdo operator: see comments for gen_repeat for details. */
1679 /* Note that gen_repeat handles its own argument evaluation. */
1681 gen_repeat (pc
, ax
, value
);
1686 struct type
*type
= (*pc
)[1].type
;
1688 gen_expr (pc
, ax
, value
);
1689 gen_cast (ax
, value
, type
);
1695 struct type
*type
= check_typedef ((*pc
)[1].type
);
1697 gen_expr (pc
, ax
, value
);
1698 /* I'm not sure I understand UNOP_MEMVAL entirely. I think
1699 it's just a hack for dealing with minsyms; you take some
1700 integer constant, pretend it's the address of an lvalue of
1701 the given type, and dereference it. */
1702 if (value
->kind
!= axs_rvalue
)
1703 /* This would be weird. */
1704 error ("GDB bug: ax-gdb.c (gen_expr): OP_MEMVAL operand isn't an rvalue???");
1706 value
->kind
= axs_lvalue_memory
;
1712 /* -FOO is equivalent to 0 - FOO. */
1713 gen_int_literal (ax
, &value1
, (LONGEST
) 0, builtin_type_int
);
1714 gen_usual_unary (ax
, &value1
); /* shouldn't do much */
1715 gen_expr (pc
, ax
, &value2
);
1716 gen_usual_unary (ax
, &value2
);
1717 gen_usual_arithmetic (ax
, &value1
, &value2
);
1718 gen_sub (ax
, value
, &value1
, &value2
);
1721 case UNOP_LOGICAL_NOT
:
1723 gen_expr (pc
, ax
, value
);
1724 gen_logical_not (ax
, value
);
1727 case UNOP_COMPLEMENT
:
1729 gen_expr (pc
, ax
, value
);
1730 gen_complement (ax
, value
);
1735 gen_expr (pc
, ax
, value
);
1736 gen_usual_unary (ax
, value
);
1737 if (TYPE_CODE (value
->type
) != TYPE_CODE_PTR
)
1738 error ("Argument of unary `*' is not a pointer.");
1739 gen_deref (ax
, value
);
1744 gen_expr (pc
, ax
, value
);
1745 gen_address_of (ax
, value
);
1750 /* Notice that gen_sizeof handles its own operand, unlike most
1751 of the other unary operator functions. This is because we
1752 have to throw away the code we generate. */
1753 gen_sizeof (pc
, ax
, value
);
1756 case STRUCTOP_STRUCT
:
1759 int length
= (*pc
)[1].longconst
;
1760 char *name
= &(*pc
)[2].string
;
1762 (*pc
) += 4 + BYTES_TO_EXP_ELEM (length
+ 1);
1763 gen_expr (pc
, ax
, value
);
1764 if (op
== STRUCTOP_STRUCT
)
1765 gen_struct_ref (ax
, value
, name
, ".", "structure or union");
1766 else if (op
== STRUCTOP_PTR
)
1767 gen_struct_ref (ax
, value
, name
, "->",
1768 "pointer to a structure or union");
1770 /* If this `if' chain doesn't handle it, then the case list
1771 shouldn't mention it, and we shouldn't be here. */
1772 error ("GDB bug: ax-gdb.c (gen_expr): unhandled struct case");
1777 error ("Attempt to use a type name as an expression.");
1780 error ("Unsupported operator in expression.");
1786 #if 0 /* not used */
1787 /* Generating bytecode from GDB expressions: driver */
1789 /* Given a GDB expression EXPR, produce a string of agent bytecode
1790 which computes its value. Return the agent expression, and set
1791 *VALUE to describe its type, and whether it's an lvalue or rvalue. */
1793 expr_to_agent (expr
, value
)
1794 struct expression
*expr
;
1795 struct axs_value
*value
;
1797 struct cleanup
*old_chain
= 0;
1798 struct agent_expr
*ax
= new_agent_expr ();
1799 union exp_element
*pc
;
1801 old_chain
= make_cleanup ((make_cleanup_func
) free_agent_expr
, ax
);
1805 gen_expr (&pc
, ax
, value
);
1807 /* We have successfully built the agent expr, so cancel the cleanup
1808 request. If we add more cleanups that we always want done, this
1809 will have to get more complicated. */
1810 discard_cleanups (old_chain
);
1815 /* Given a GDB expression EXPR denoting an lvalue in memory, produce a
1816 string of agent bytecode which will leave its address and size on
1817 the top of stack. Return the agent expression.
1819 Not sure this function is useful at all. */
1821 expr_to_address_and_size (expr
)
1822 struct expression
*expr
;
1824 struct axs_value value
;
1825 struct agent_expr
*ax
= expr_to_agent (expr
, &value
);
1827 /* Complain if the result is not a memory lvalue. */
1828 if (value
.kind
!= axs_lvalue_memory
)
1830 free_agent_expr (ax
);
1831 error ("Expression does not denote an object in memory.");
1834 /* Push the object's size on the stack. */
1835 ax_const_l (ax
, TYPE_LENGTH (value
.type
));
1841 /* Given a GDB expression EXPR, return bytecode to trace its value.
1842 The result will use the `trace' and `trace_quick' bytecodes to
1843 record the value of all memory touched by the expression. The
1844 caller can then use the ax_reqs function to discover which
1845 registers it relies upon. */
1847 gen_trace_for_expr (scope
, expr
)
1849 struct expression
*expr
;
1851 struct cleanup
*old_chain
= 0;
1852 struct agent_expr
*ax
= new_agent_expr (scope
);
1853 union exp_element
*pc
;
1854 struct axs_value value
;
1856 old_chain
= make_cleanup ((make_cleanup_func
) free_agent_expr
, ax
);
1860 gen_expr (&pc
, ax
, &value
);
1862 /* Make sure we record the final object, and get rid of it. */
1863 gen_traced_pop (ax
, &value
);
1865 /* Oh, and terminate. */
1866 ax_simple (ax
, aop_end
);
1868 /* We have successfully built the agent expr, so cancel the cleanup
1869 request. If we add more cleanups that we always want done, this
1870 will have to get more complicated. */
1871 discard_cleanups (old_chain
);
1877 /* The "agent" command, for testing: compile and disassemble an expression. */
1880 print_axs_value (f
, value
)
1882 struct axs_value
*value
;
1884 switch (value
->kind
)
1887 fputs_filtered ("rvalue", f
);
1890 case axs_lvalue_memory
:
1891 fputs_filtered ("memory lvalue", f
);
1894 case axs_lvalue_register
:
1895 fprintf_filtered (f
, "register %d lvalue", value
->u
.reg
);
1899 fputs_filtered (" : ", f
);
1900 type_print (value
->type
, "", f
, -1);
1905 agent_command (exp
, from_tty
)
1909 struct cleanup
*old_chain
= 0;
1910 struct expression
*expr
;
1911 struct agent_expr
*agent
;
1912 struct frame_info
*fi
= get_current_frame (); /* need current scope */
1914 /* We don't deal with overlay debugging at the moment. We need to
1915 think more carefully about this. If you copy this code into
1916 another command, change the error message; the user shouldn't
1917 have to know anything about agent expressions. */
1918 if (overlay_debugging
)
1919 error ("GDB can't do agent expression translation with overlays.");
1922 error_no_arg ("expression to translate");
1924 expr
= parse_expression (exp
);
1925 old_chain
= make_cleanup ((make_cleanup_func
) free_current_contents
, &expr
);
1926 agent
= gen_trace_for_expr (fi
->pc
, expr
);
1927 make_cleanup ((make_cleanup_func
) free_agent_expr
, agent
);
1928 ax_print (gdb_stdout
, agent
);
1930 /* It would be nice to call ax_reqs here to gather some general info
1931 about the expression, and then print out the result. */
1933 do_cleanups (old_chain
);
1938 /* Initialization code. */
1940 void _initialize_ax_gdb
PARAMS ((void));
1942 _initialize_ax_gdb ()
1944 add_cmd ("agent", class_maintenance
, agent_command
,
1945 "Translate an expression into remote agent bytecode.",