61baf725ec
This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
283 lines
10 KiB
C++
283 lines
10 KiB
C++
/* Definitions for expressions designed to be executed on the agent
|
||
Copyright (C) 1998-2017 Free Software Foundation, Inc.
|
||
|
||
This file is part of GDB.
|
||
|
||
This program 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 3 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, see <http://www.gnu.org/licenses/>. */
|
||
|
||
#ifndef AGENTEXPR_H
|
||
#define AGENTEXPR_H
|
||
|
||
#include "doublest.h" /* For DOUBLEST. */
|
||
#include "vec.h"
|
||
|
||
/* It's sometimes useful to be able to debug programs that you can't
|
||
really stop for more than a fraction of a second. To this end, the
|
||
user can specify a tracepoint (like a breakpoint, but you don't
|
||
stop at it), and specify a bunch of expressions to record the
|
||
values of when that tracepoint is reached. As the program runs,
|
||
GDB collects the values. At any point (possibly while values are
|
||
still being collected), the user can display the collected values.
|
||
|
||
This is used with remote debugging; we don't really support it on
|
||
native configurations.
|
||
|
||
This means that expressions are being evaluated by the remote agent,
|
||
which doesn't have any access to the symbol table information, and
|
||
needs to be small and simple.
|
||
|
||
The agent_expr routines and datatypes are a bytecode language
|
||
designed to be executed by the agent. Agent expressions work in
|
||
terms of fixed-width values, operators, memory references, and
|
||
register references. You can evaluate a agent expression just given
|
||
a bunch of memory and register values to sniff at; you don't need
|
||
any symbolic information like variable names, types, etc.
|
||
|
||
GDB translates source expressions, whose meaning depends on
|
||
symbolic information, into agent bytecode expressions, whose meaning
|
||
is independent of symbolic information. This means the agent can
|
||
evaluate them on the fly without reference to data only available
|
||
to the host GDB. */
|
||
|
||
|
||
/* Different kinds of flaws an agent expression might have, as
|
||
detected by ax_reqs. */
|
||
enum agent_flaws
|
||
{
|
||
agent_flaw_none = 0, /* code is good */
|
||
|
||
/* There is an invalid instruction in the stream. */
|
||
agent_flaw_bad_instruction,
|
||
|
||
/* There is an incomplete instruction at the end of the expression. */
|
||
agent_flaw_incomplete_instruction,
|
||
|
||
/* ax_reqs was unable to prove that every jump target is to a
|
||
valid offset. Valid offsets are within the bounds of the
|
||
expression, and to a valid instruction boundary. */
|
||
agent_flaw_bad_jump,
|
||
|
||
/* ax_reqs was unable to prove to its satisfaction that, for each
|
||
jump target location, the stack will have the same height whether
|
||
that location is reached via a jump or by straight execution. */
|
||
agent_flaw_height_mismatch,
|
||
|
||
/* ax_reqs was unable to prove that every instruction following
|
||
an unconditional jump was the target of some other jump. */
|
||
agent_flaw_hole
|
||
};
|
||
|
||
/* Agent expression data structures. */
|
||
|
||
/* The type of an element of the agent expression stack.
|
||
The bytecode operation indicates which element we should access;
|
||
the value itself has no typing information. GDB generates all
|
||
bytecode streams, so we don't have to worry about type errors. */
|
||
|
||
union agent_val
|
||
{
|
||
LONGEST l;
|
||
DOUBLEST d;
|
||
};
|
||
|
||
/* A buffer containing a agent expression. */
|
||
struct agent_expr
|
||
{
|
||
/* Construct an empty agent expression. */
|
||
explicit agent_expr (struct gdbarch *gdbarch, CORE_ADDR scope);
|
||
|
||
~agent_expr ();
|
||
|
||
/* The bytes of the expression. */
|
||
unsigned char *buf;
|
||
|
||
/* The number of bytecode in the expression. */
|
||
int len;
|
||
|
||
/* Allocated space available currently. */
|
||
int size;
|
||
|
||
/* The target architecture assumed to be in effect. */
|
||
struct gdbarch *gdbarch;
|
||
|
||
/* The address to which the expression applies. */
|
||
CORE_ADDR scope;
|
||
|
||
/* If the following is not equal to agent_flaw_none, the rest of the
|
||
information in this structure is suspect. */
|
||
enum agent_flaws flaw;
|
||
|
||
/* Number of elements left on stack at end; may be negative if expr
|
||
only consumes elements. */
|
||
int final_height;
|
||
|
||
/* Maximum and minimum stack height, relative to initial height. */
|
||
int max_height, min_height;
|
||
|
||
/* Largest `ref' or `const' opcode used, in bits. Zero means the
|
||
expression has no such instructions. */
|
||
int max_data_size;
|
||
|
||
/* Bit vector of registers needed. Register R is needed iff
|
||
|
||
reg_mask[R / 8] & (1 << (R % 8))
|
||
|
||
is non-zero. Note! You may not assume that this bitmask is long
|
||
enough to hold bits for all the registers of the machine; the
|
||
agent expression code has no idea how many registers the machine
|
||
has. However, the bitmask is reg_mask_len bytes long, so the
|
||
valid register numbers run from 0 to reg_mask_len * 8 - 1.
|
||
|
||
Also note that this mask may contain registers that are needed
|
||
for the original collection expression to work, but that are
|
||
not referenced by any bytecode. This could, for example, occur
|
||
when collecting a local variable allocated to a register; the
|
||
compiler sets the mask bit and skips generating a bytecode whose
|
||
result is going to be discarded anyway.
|
||
*/
|
||
int reg_mask_len;
|
||
unsigned char *reg_mask;
|
||
|
||
/* For the data tracing facility, we need to insert `trace' bytecodes
|
||
before each data fetch; this records all the memory that the
|
||
expression touches in the course of evaluation, so that memory will
|
||
be available when the user later tries to evaluate the expression
|
||
in GDB.
|
||
|
||
Setting the flag 'tracing' to non-zero enables the code that
|
||
emits the trace bytecodes at the appropriate points. */
|
||
|
||
unsigned int tracing : 1;
|
||
|
||
/* This indicates that pointers to chars should get an added
|
||
tracenz bytecode to record nonzero bytes, up to a length that
|
||
is the value of trace_string. */
|
||
|
||
int trace_string;
|
||
};
|
||
|
||
/* An agent_expr owning pointer. */
|
||
typedef std::unique_ptr<agent_expr> agent_expr_up;
|
||
|
||
/* The actual values of the various bytecode operations. */
|
||
|
||
enum agent_op
|
||
{
|
||
#define DEFOP(NAME, SIZE, DATA_SIZE, CONSUMED, PRODUCED, VALUE) \
|
||
aop_ ## NAME = VALUE,
|
||
#include "ax.def"
|
||
#undef DEFOP
|
||
aop_last
|
||
};
|
||
|
||
|
||
|
||
/* Functions for building expressions. */
|
||
|
||
/* Append a raw byte to EXPR. */
|
||
extern void ax_raw_byte (struct agent_expr *expr, gdb_byte byte);
|
||
|
||
/* Append a simple operator OP to EXPR. */
|
||
extern void ax_simple (struct agent_expr *EXPR, enum agent_op OP);
|
||
|
||
/* Append a pick operator to EXPR. DEPTH is the stack item to pick,
|
||
with 0 being top of stack. */
|
||
extern void ax_pick (struct agent_expr *EXPR, int DEPTH);
|
||
|
||
/* Append the floating-point prefix, for the next bytecode. */
|
||
#define ax_float(EXPR) (ax_simple ((EXPR), aop_float))
|
||
|
||
/* Append a sign-extension instruction to EXPR, to extend an N-bit value. */
|
||
extern void ax_ext (struct agent_expr *EXPR, int N);
|
||
|
||
/* Append a zero-extension instruction to EXPR, to extend an N-bit value. */
|
||
extern void ax_zero_ext (struct agent_expr *EXPR, int N);
|
||
|
||
/* Append a trace_quick instruction to EXPR, to record N bytes. */
|
||
extern void ax_trace_quick (struct agent_expr *EXPR, int N);
|
||
|
||
/* Append a goto op to EXPR. OP is the actual op (must be aop_goto or
|
||
aop_if_goto). We assume we don't know the target offset yet,
|
||
because it's probably a forward branch, so we leave space in EXPR
|
||
for the target, and return the offset in EXPR of that space, so we
|
||
can backpatch it once we do know the target offset. Use ax_label
|
||
to do the backpatching. */
|
||
extern int ax_goto (struct agent_expr *EXPR, enum agent_op OP);
|
||
|
||
/* Suppose a given call to ax_goto returns some value PATCH. When you
|
||
know the offset TARGET that goto should jump to, call
|
||
ax_label (EXPR, PATCH, TARGET)
|
||
to patch TARGET into the ax_goto instruction. */
|
||
extern void ax_label (struct agent_expr *EXPR, int patch, int target);
|
||
|
||
/* Assemble code to push a constant on the stack. */
|
||
extern void ax_const_l (struct agent_expr *EXPR, LONGEST l);
|
||
extern void ax_const_d (struct agent_expr *EXPR, LONGEST d);
|
||
|
||
/* Assemble code to push the value of register number REG on the
|
||
stack. */
|
||
extern void ax_reg (struct agent_expr *EXPR, int REG);
|
||
|
||
/* Add the given register to the register mask of the expression. */
|
||
extern void ax_reg_mask (struct agent_expr *ax, int reg);
|
||
|
||
/* Assemble code to operate on a trace state variable. */
|
||
extern void ax_tsv (struct agent_expr *expr, enum agent_op op, int num);
|
||
|
||
/* Append a string to the bytecode stream. */
|
||
extern void ax_string (struct agent_expr *x, const char *str, int slen);
|
||
|
||
|
||
/* Functions for printing out expressions, and otherwise debugging
|
||
things. */
|
||
|
||
/* Disassemble the expression EXPR, writing to F. */
|
||
extern void ax_print (struct ui_file *f, struct agent_expr * EXPR);
|
||
|
||
/* An entry in the opcode map. */
|
||
struct aop_map
|
||
{
|
||
|
||
/* The name of the opcode. Null means that this entry is not a
|
||
valid opcode --- a hole in the opcode space. */
|
||
const char *name;
|
||
|
||
/* All opcodes take no operands from the bytecode stream, or take
|
||
unsigned integers of various sizes. If this is a positive number
|
||
n, then the opcode is followed by an n-byte operand, which should
|
||
be printed as an unsigned integer. If this is zero, then the
|
||
opcode takes no operands from the bytecode stream.
|
||
|
||
If we get more complicated opcodes in the future, don't add other
|
||
magic values of this; that's a crock. Add an `enum encoding'
|
||
field to this, or something like that. */
|
||
int op_size;
|
||
|
||
/* The size of the data operated upon, in bits, for bytecodes that
|
||
care about that (ref and const). Zero for all others. */
|
||
int data_size;
|
||
|
||
/* Number of stack elements consumed, and number produced. */
|
||
int consumed, produced;
|
||
};
|
||
|
||
/* Map of the bytecodes, indexed by bytecode number. */
|
||
extern struct aop_map aop_map[];
|
||
|
||
/* Given an agent expression AX, analyze and update its requirements. */
|
||
|
||
extern void ax_reqs (struct agent_expr *ax);
|
||
|
||
#endif /* AGENTEXPR_H */
|