mirror of
https://github.com/darlinghq/darling-gdb.git
synced 2024-12-01 07:50:49 +00:00
589 lines
14 KiB
C
589 lines
14 KiB
C
/* Prologue value handling for GDB.
|
||
Copyright 2003, 2004, 2005, 2007, 2008 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/>. */
|
||
|
||
#include "defs.h"
|
||
#include "gdb_string.h"
|
||
#include "gdb_assert.h"
|
||
#include "prologue-value.h"
|
||
#include "regcache.h"
|
||
|
||
|
||
/* Constructors. */
|
||
|
||
pv_t
|
||
pv_unknown (void)
|
||
{
|
||
pv_t v = { pvk_unknown, 0, 0 };
|
||
|
||
return v;
|
||
}
|
||
|
||
|
||
pv_t
|
||
pv_constant (CORE_ADDR k)
|
||
{
|
||
pv_t v;
|
||
|
||
v.kind = pvk_constant;
|
||
v.reg = -1; /* for debugging */
|
||
v.k = k;
|
||
|
||
return v;
|
||
}
|
||
|
||
|
||
pv_t
|
||
pv_register (int reg, CORE_ADDR k)
|
||
{
|
||
pv_t v;
|
||
|
||
v.kind = pvk_register;
|
||
v.reg = reg;
|
||
v.k = k;
|
||
|
||
return v;
|
||
}
|
||
|
||
|
||
|
||
/* Arithmetic operations. */
|
||
|
||
/* If one of *A and *B is a constant, and the other isn't, swap the
|
||
values as necessary to ensure that *B is the constant. This can
|
||
reduce the number of cases we need to analyze in the functions
|
||
below. */
|
||
static void
|
||
constant_last (pv_t *a, pv_t *b)
|
||
{
|
||
if (a->kind == pvk_constant
|
||
&& b->kind != pvk_constant)
|
||
{
|
||
pv_t temp = *a;
|
||
*a = *b;
|
||
*b = temp;
|
||
}
|
||
}
|
||
|
||
|
||
pv_t
|
||
pv_add (pv_t a, pv_t b)
|
||
{
|
||
constant_last (&a, &b);
|
||
|
||
/* We can add a constant to a register. */
|
||
if (a.kind == pvk_register
|
||
&& b.kind == pvk_constant)
|
||
return pv_register (a.reg, a.k + b.k);
|
||
|
||
/* We can add a constant to another constant. */
|
||
else if (a.kind == pvk_constant
|
||
&& b.kind == pvk_constant)
|
||
return pv_constant (a.k + b.k);
|
||
|
||
/* Anything else we don't know how to add. We don't have a
|
||
representation for, say, the sum of two registers, or a multiple
|
||
of a register's value (adding a register to itself). */
|
||
else
|
||
return pv_unknown ();
|
||
}
|
||
|
||
|
||
pv_t
|
||
pv_add_constant (pv_t v, CORE_ADDR k)
|
||
{
|
||
/* Rather than thinking of all the cases we can and can't handle,
|
||
we'll just let pv_add take care of that for us. */
|
||
return pv_add (v, pv_constant (k));
|
||
}
|
||
|
||
|
||
pv_t
|
||
pv_subtract (pv_t a, pv_t b)
|
||
{
|
||
/* This isn't quite the same as negating B and adding it to A, since
|
||
we don't have a representation for the negation of anything but a
|
||
constant. For example, we can't negate { pvk_register, R1, 10 },
|
||
but we do know that { pvk_register, R1, 10 } minus { pvk_register,
|
||
R1, 5 } is { pvk_constant, <ignored>, 5 }.
|
||
|
||
This means, for example, that we could subtract two stack
|
||
addresses; they're both relative to the original SP. Since the
|
||
frame pointer is set based on the SP, its value will be the
|
||
original SP plus some constant (probably zero), so we can use its
|
||
value just fine, too. */
|
||
|
||
constant_last (&a, &b);
|
||
|
||
/* We can subtract two constants. */
|
||
if (a.kind == pvk_constant
|
||
&& b.kind == pvk_constant)
|
||
return pv_constant (a.k - b.k);
|
||
|
||
/* We can subtract a constant from a register. */
|
||
else if (a.kind == pvk_register
|
||
&& b.kind == pvk_constant)
|
||
return pv_register (a.reg, a.k - b.k);
|
||
|
||
/* We can subtract a register from itself, yielding a constant. */
|
||
else if (a.kind == pvk_register
|
||
&& b.kind == pvk_register
|
||
&& a.reg == b.reg)
|
||
return pv_constant (a.k - b.k);
|
||
|
||
/* We don't know how to subtract anything else. */
|
||
else
|
||
return pv_unknown ();
|
||
}
|
||
|
||
|
||
pv_t
|
||
pv_logical_and (pv_t a, pv_t b)
|
||
{
|
||
constant_last (&a, &b);
|
||
|
||
/* We can 'and' two constants. */
|
||
if (a.kind == pvk_constant
|
||
&& b.kind == pvk_constant)
|
||
return pv_constant (a.k & b.k);
|
||
|
||
/* We can 'and' anything with the constant zero. */
|
||
else if (b.kind == pvk_constant
|
||
&& b.k == 0)
|
||
return pv_constant (0);
|
||
|
||
/* We can 'and' anything with ~0. */
|
||
else if (b.kind == pvk_constant
|
||
&& b.k == ~ (CORE_ADDR) 0)
|
||
return a;
|
||
|
||
/* We can 'and' a register with itself. */
|
||
else if (a.kind == pvk_register
|
||
&& b.kind == pvk_register
|
||
&& a.reg == b.reg
|
||
&& a.k == b.k)
|
||
return a;
|
||
|
||
/* Otherwise, we don't know. */
|
||
else
|
||
return pv_unknown ();
|
||
}
|
||
|
||
|
||
|
||
/* Examining prologue values. */
|
||
|
||
int
|
||
pv_is_identical (pv_t a, pv_t b)
|
||
{
|
||
if (a.kind != b.kind)
|
||
return 0;
|
||
|
||
switch (a.kind)
|
||
{
|
||
case pvk_unknown:
|
||
return 1;
|
||
case pvk_constant:
|
||
return (a.k == b.k);
|
||
case pvk_register:
|
||
return (a.reg == b.reg && a.k == b.k);
|
||
default:
|
||
gdb_assert (0);
|
||
}
|
||
}
|
||
|
||
|
||
int
|
||
pv_is_constant (pv_t a)
|
||
{
|
||
return (a.kind == pvk_constant);
|
||
}
|
||
|
||
|
||
int
|
||
pv_is_register (pv_t a, int r)
|
||
{
|
||
return (a.kind == pvk_register
|
||
&& a.reg == r);
|
||
}
|
||
|
||
|
||
int
|
||
pv_is_register_k (pv_t a, int r, CORE_ADDR k)
|
||
{
|
||
return (a.kind == pvk_register
|
||
&& a.reg == r
|
||
&& a.k == k);
|
||
}
|
||
|
||
|
||
enum pv_boolean
|
||
pv_is_array_ref (pv_t addr, CORE_ADDR size,
|
||
pv_t array_addr, CORE_ADDR array_len,
|
||
CORE_ADDR elt_size,
|
||
int *i)
|
||
{
|
||
/* Note that, since .k is a CORE_ADDR, and CORE_ADDR is unsigned, if
|
||
addr is *before* the start of the array, then this isn't going to
|
||
be negative... */
|
||
pv_t offset = pv_subtract (addr, array_addr);
|
||
|
||
if (offset.kind == pvk_constant)
|
||
{
|
||
/* This is a rather odd test. We want to know if the SIZE bytes
|
||
at ADDR don't overlap the array at all, so you'd expect it to
|
||
be an || expression: "if we're completely before || we're
|
||
completely after". But with unsigned arithmetic, things are
|
||
different: since it's a number circle, not a number line, the
|
||
right values for offset.k are actually one contiguous range. */
|
||
if (offset.k <= -size
|
||
&& offset.k >= array_len * elt_size)
|
||
return pv_definite_no;
|
||
else if (offset.k % elt_size != 0
|
||
|| size != elt_size)
|
||
return pv_maybe;
|
||
else
|
||
{
|
||
*i = offset.k / elt_size;
|
||
return pv_definite_yes;
|
||
}
|
||
}
|
||
else
|
||
return pv_maybe;
|
||
}
|
||
|
||
|
||
|
||
/* Areas. */
|
||
|
||
|
||
/* A particular value known to be stored in an area.
|
||
|
||
Entries form a ring, sorted by unsigned offset from the area's base
|
||
register's value. Since entries can straddle the wrap-around point,
|
||
unsigned offsets form a circle, not a number line, so the list
|
||
itself is structured the same way --- there is no inherent head.
|
||
The entry with the lowest offset simply follows the entry with the
|
||
highest offset. Entries may abut, but never overlap. The area's
|
||
'entry' pointer points to an arbitrary node in the ring. */
|
||
struct area_entry
|
||
{
|
||
/* Links in the doubly-linked ring. */
|
||
struct area_entry *prev, *next;
|
||
|
||
/* Offset of this entry's address from the value of the base
|
||
register. */
|
||
CORE_ADDR offset;
|
||
|
||
/* The size of this entry. Note that an entry may wrap around from
|
||
the end of the address space to the beginning. */
|
||
CORE_ADDR size;
|
||
|
||
/* The value stored here. */
|
||
pv_t value;
|
||
};
|
||
|
||
|
||
struct pv_area
|
||
{
|
||
/* This area's base register. */
|
||
int base_reg;
|
||
|
||
/* The mask to apply to addresses, to make the wrap-around happen at
|
||
the right place. */
|
||
CORE_ADDR addr_mask;
|
||
|
||
/* An element of the doubly-linked ring of entries, or zero if we
|
||
have none. */
|
||
struct area_entry *entry;
|
||
};
|
||
|
||
|
||
struct pv_area *
|
||
make_pv_area (int base_reg)
|
||
{
|
||
struct pv_area *a = (struct pv_area *) xmalloc (sizeof (*a));
|
||
|
||
memset (a, 0, sizeof (*a));
|
||
|
||
a->base_reg = base_reg;
|
||
a->entry = 0;
|
||
|
||
/* Remember that shift amounts equal to the type's width are
|
||
undefined. */
|
||
a->addr_mask = ((((CORE_ADDR) 1
|
||
<< (gdbarch_addr_bit (current_gdbarch) - 1)) - 1) << 1) | 1;
|
||
|
||
return a;
|
||
}
|
||
|
||
|
||
/* Delete all entries from AREA. */
|
||
static void
|
||
clear_entries (struct pv_area *area)
|
||
{
|
||
struct area_entry *e = area->entry;
|
||
|
||
if (e)
|
||
{
|
||
/* This needs to be a do-while loop, in order to actually
|
||
process the node being checked for in the terminating
|
||
condition. */
|
||
do
|
||
{
|
||
struct area_entry *next = e->next;
|
||
xfree (e);
|
||
e = next;
|
||
}
|
||
while (e != area->entry);
|
||
|
||
area->entry = 0;
|
||
}
|
||
}
|
||
|
||
|
||
void
|
||
free_pv_area (struct pv_area *area)
|
||
{
|
||
clear_entries (area);
|
||
xfree (area);
|
||
}
|
||
|
||
|
||
static void
|
||
do_free_pv_area_cleanup (void *arg)
|
||
{
|
||
free_pv_area ((struct pv_area *) arg);
|
||
}
|
||
|
||
|
||
struct cleanup *
|
||
make_cleanup_free_pv_area (struct pv_area *area)
|
||
{
|
||
return make_cleanup (do_free_pv_area_cleanup, (void *) area);
|
||
}
|
||
|
||
|
||
int
|
||
pv_area_store_would_trash (struct pv_area *area, pv_t addr)
|
||
{
|
||
/* It may seem odd that pvk_constant appears here --- after all,
|
||
that's the case where we know the most about the address! But
|
||
pv_areas are always relative to a register, and we don't know the
|
||
value of the register, so we can't compare entry addresses to
|
||
constants. */
|
||
return (addr.kind == pvk_unknown
|
||
|| addr.kind == pvk_constant
|
||
|| (addr.kind == pvk_register && addr.reg != area->base_reg));
|
||
}
|
||
|
||
|
||
/* Return a pointer to the first entry we hit in AREA starting at
|
||
OFFSET and going forward.
|
||
|
||
This may return zero, if AREA has no entries.
|
||
|
||
And since the entries are a ring, this may return an entry that
|
||
entirely preceeds OFFSET. This is the correct behavior: depending
|
||
on the sizes involved, we could still overlap such an area, with
|
||
wrap-around. */
|
||
static struct area_entry *
|
||
find_entry (struct pv_area *area, CORE_ADDR offset)
|
||
{
|
||
struct area_entry *e = area->entry;
|
||
|
||
if (! e)
|
||
return 0;
|
||
|
||
/* If the next entry would be better than the current one, then scan
|
||
forward. Since we use '<' in this loop, it always terminates.
|
||
|
||
Note that, even setting aside the addr_mask stuff, we must not
|
||
simplify this, in high school algebra fashion, to
|
||
(e->next->offset < e->offset), because of the way < interacts
|
||
with wrap-around. We have to subtract offset from both sides to
|
||
make sure both things we're comparing are on the same side of the
|
||
discontinuity. */
|
||
while (((e->next->offset - offset) & area->addr_mask)
|
||
< ((e->offset - offset) & area->addr_mask))
|
||
e = e->next;
|
||
|
||
/* If the previous entry would be better than the current one, then
|
||
scan backwards. */
|
||
while (((e->prev->offset - offset) & area->addr_mask)
|
||
< ((e->offset - offset) & area->addr_mask))
|
||
e = e->prev;
|
||
|
||
/* In case there's some locality to the searches, set the area's
|
||
pointer to the entry we've found. */
|
||
area->entry = e;
|
||
|
||
return e;
|
||
}
|
||
|
||
|
||
/* Return non-zero if the SIZE bytes at OFFSET would overlap ENTRY;
|
||
return zero otherwise. AREA is the area to which ENTRY belongs. */
|
||
static int
|
||
overlaps (struct pv_area *area,
|
||
struct area_entry *entry,
|
||
CORE_ADDR offset,
|
||
CORE_ADDR size)
|
||
{
|
||
/* Think carefully about wrap-around before simplifying this. */
|
||
return (((entry->offset - offset) & area->addr_mask) < size
|
||
|| ((offset - entry->offset) & area->addr_mask) < entry->size);
|
||
}
|
||
|
||
|
||
void
|
||
pv_area_store (struct pv_area *area,
|
||
pv_t addr,
|
||
CORE_ADDR size,
|
||
pv_t value)
|
||
{
|
||
/* Remove any (potentially) overlapping entries. */
|
||
if (pv_area_store_would_trash (area, addr))
|
||
clear_entries (area);
|
||
else
|
||
{
|
||
CORE_ADDR offset = addr.k;
|
||
struct area_entry *e = find_entry (area, offset);
|
||
|
||
/* Delete all entries that we would overlap. */
|
||
while (e && overlaps (area, e, offset, size))
|
||
{
|
||
struct area_entry *next = (e->next == e) ? 0 : e->next;
|
||
e->prev->next = e->next;
|
||
e->next->prev = e->prev;
|
||
|
||
xfree (e);
|
||
e = next;
|
||
}
|
||
|
||
/* Move the area's pointer to the next remaining entry. This
|
||
will also zero the pointer if we've deleted all the entries. */
|
||
area->entry = e;
|
||
}
|
||
|
||
/* Now, there are no entries overlapping us, and area->entry is
|
||
either zero or pointing at the closest entry after us. We can
|
||
just insert ourselves before that.
|
||
|
||
But if we're storing an unknown value, don't bother --- that's
|
||
the default. */
|
||
if (value.kind == pvk_unknown)
|
||
return;
|
||
else
|
||
{
|
||
CORE_ADDR offset = addr.k;
|
||
struct area_entry *e = (struct area_entry *) xmalloc (sizeof (*e));
|
||
e->offset = offset;
|
||
e->size = size;
|
||
e->value = value;
|
||
|
||
if (area->entry)
|
||
{
|
||
e->prev = area->entry->prev;
|
||
e->next = area->entry;
|
||
e->prev->next = e->next->prev = e;
|
||
}
|
||
else
|
||
{
|
||
e->prev = e->next = e;
|
||
area->entry = e;
|
||
}
|
||
}
|
||
}
|
||
|
||
|
||
pv_t
|
||
pv_area_fetch (struct pv_area *area, pv_t addr, CORE_ADDR size)
|
||
{
|
||
/* If we have no entries, or we can't decide how ADDR relates to the
|
||
entries we do have, then the value is unknown. */
|
||
if (! area->entry
|
||
|| pv_area_store_would_trash (area, addr))
|
||
return pv_unknown ();
|
||
else
|
||
{
|
||
CORE_ADDR offset = addr.k;
|
||
struct area_entry *e = find_entry (area, offset);
|
||
|
||
/* If this entry exactly matches what we're looking for, then
|
||
we're set. Otherwise, say it's unknown. */
|
||
if (e->offset == offset && e->size == size)
|
||
return e->value;
|
||
else
|
||
return pv_unknown ();
|
||
}
|
||
}
|
||
|
||
|
||
int
|
||
pv_area_find_reg (struct pv_area *area,
|
||
struct gdbarch *gdbarch,
|
||
int reg,
|
||
CORE_ADDR *offset_p)
|
||
{
|
||
struct area_entry *e = area->entry;
|
||
|
||
if (e)
|
||
do
|
||
{
|
||
if (e->value.kind == pvk_register
|
||
&& e->value.reg == reg
|
||
&& e->value.k == 0
|
||
&& e->size == register_size (gdbarch, reg))
|
||
{
|
||
if (offset_p)
|
||
*offset_p = e->offset;
|
||
return 1;
|
||
}
|
||
|
||
e = e->next;
|
||
}
|
||
while (e != area->entry);
|
||
|
||
return 0;
|
||
}
|
||
|
||
|
||
void
|
||
pv_area_scan (struct pv_area *area,
|
||
void (*func) (void *closure,
|
||
pv_t addr,
|
||
CORE_ADDR size,
|
||
pv_t value),
|
||
void *closure)
|
||
{
|
||
struct area_entry *e = area->entry;
|
||
pv_t addr;
|
||
|
||
addr.kind = pvk_register;
|
||
addr.reg = area->base_reg;
|
||
|
||
if (e)
|
||
do
|
||
{
|
||
addr.k = e->offset;
|
||
func (closure, addr, e->size, e->value);
|
||
e = e->next;
|
||
}
|
||
while (e != area->entry);
|
||
}
|