1 /* GDB-specific functions for operating on agent expressions
2 Copyright (C) 1998-2017 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 3 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, see <http://www.gnu.org/licenses/>. */
22 #include "ax.h" /* For agent_expr_up. */
29 /* GDB stores expressions in the form of a flattened tree (struct
30 expression), so we just walk that tree and generate agent bytecodes
33 GDB's normal evaluation uses struct value, which contains the
34 expression's value as well as its address or the register it came
35 from. The `+' operator uses the value, whereas the unary `&'
36 operator will use the address portion. The `=' operator will use
37 the address or register number of its left hand side.
39 The issues are different when generating agent bytecode. Given a
40 variable reference expression, we should not necessarily generate
41 code to fetch its value, because the next operator may be `=' or
42 unary `&'. Instead, when we recurse on a subexpression, we
43 indicate whether we want that expression to produce an lvalue or an
44 rvalue. If we requested an lvalue, then the recursive call tells
45 us whether it generated code to compute an address on the stack, or
46 whether the lvalue lives in a register.
48 The `axs' prefix here means `agent expression, static', because
49 this is all static analysis of the expression, i.e. analysis which
50 doesn't depend on the contents of memory and registers. */
53 /* Different kinds of agent expression static values. */
56 /* We generated code to compute the subexpression's value.
57 Constants and arithmetic operators yield this. */
60 /* We generated code to yield the subexpression's value's address on
61 the top of the stack. If the caller needs an rvalue, it should
62 call require_rvalue to produce the rvalue from this address. */
65 /* We didn't generate any code, and the stack is undisturbed,
66 because the subexpression's value lives in a register; u.reg is
67 the register number. If the caller needs an rvalue, it should
68 call require_rvalue to produce the rvalue from this register
73 /* Structure describing what we got from a subexpression. Think of
74 this as parallel to value.h's enum lval_type, except that we're
75 describing a value which will exist when the expression is
76 evaluated in the future, not a value we have in our hand. */
79 enum axs_lvalue_kind kind
; /* see above */
81 /* The type of the subexpression. Even if lvalue == axs_lvalue_memory,
82 this is the type of the value itself; the value on the stack is a
83 "pointer to" an object of this type. */
86 /* If nonzero, this is a variable which does not actually exist in
92 /* if kind == axs_lvalue_register, this is the register number */
99 /* Translating GDB expressions into agent expressions. */
101 /* Given a GDB expression EXPR, return bytecode to trace its value.
102 The result will use the `trace' and `trace_quick' bytecodes to
103 record the value of all memory touched by the expression, and leave
104 no values on the stack. The caller can then use the ax_reqs
105 function to discover which registers the expression uses. */
106 extern agent_expr_up
gen_trace_for_expr (CORE_ADDR
, struct expression
*,
109 extern agent_expr_up
gen_trace_for_var (CORE_ADDR
, struct gdbarch
*,
110 struct symbol
*, int);
112 extern agent_expr_up
gen_trace_for_return_address (CORE_ADDR
,
116 extern agent_expr_up
gen_eval_for_expr (CORE_ADDR
, struct expression
*);
118 extern void gen_expr (struct expression
*exp
, union exp_element
**pc
,
119 struct agent_expr
*ax
, struct axs_value
*value
);
121 extern void require_rvalue (struct agent_expr
*ax
, struct axs_value
*value
);
124 extern agent_expr_up
gen_printf (CORE_ADDR
, struct gdbarch
*,
125 CORE_ADDR
, LONGEST
, const char *, int,
126 struct format_piece
*,
127 int, struct expression
**);
129 #endif /* AX_GDB_H */
This page took 0.031336 seconds and 4 git commands to generate.