blob: 8ba886c3efc84c4885cb0a529a26991fd1978cd3 [file] [log] [blame]
/* Inline frame unwinder for GDB.
Copyright (C) 2008-2024 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 "breakpoint.h"
#include "inline-frame.h"
#include "addrmap.h"
#include "block.h"
#include "frame-unwind.h"
#include "inferior.h"
#include "gdbthread.h"
#include "regcache.h"
#include "symtab.h"
#include "frame.h"
#include "cli/cli-cmds.h"
#include "cli/cli-style.h"
#include <algorithm>
/* We need to save a few variables for every thread stopped at the
virtual call site of an inlined function. If there was always a
"struct thread_info", we could hang it off that; in the mean time,
keep our own list. */
struct inline_state
{
inline_state (thread_info *thread_, int skipped_frames_, CORE_ADDR saved_pc_,
std::vector<const symbol *> &&function_symbols_)
: thread (thread_), skipped_frames (skipped_frames_), saved_pc (saved_pc_),
function_symbols (std::move (function_symbols_))
{}
/* The thread this data relates to. It should be a currently
stopped thread. */
thread_info *thread;
/* The number of inlined functions we are skipping. Each of these
functions can be stepped in to. */
int skipped_frames;
/* This is the PC used when calculating FUNCTION_SYMBOLS; used to check
whether we have moved to a new location by user request. If so, we
invalidate any skipped frames. */
CORE_ADDR saved_pc;
/* The list of all inline functions that start at SAVED_PC, except for
the last entry which will either be a non-inline function, or an
inline function that doesn't start at SAVED_PC. This last entry is
the function that "contains" all of the earlier functions.
This list can be empty if SAVED_PC is for a code region which is not
covered by any function (inline or non-inline). */
std::vector<const symbol *> function_symbols;
};
static std::vector<inline_state> inline_states;
/* Locate saved inlined frame state for THREAD, if it exists and is
valid. */
static struct inline_state *
find_inline_frame_state (thread_info *thread)
{
auto state_it = std::find_if (inline_states.begin (), inline_states.end (),
[thread] (const inline_state &state)
{
return state.thread == thread;
});
if (state_it == inline_states.end ())
return nullptr;
inline_state &state = *state_it;
struct regcache *regcache = get_thread_regcache (thread);
CORE_ADDR current_pc = regcache_read_pc (regcache);
if (current_pc != state.saved_pc)
{
/* PC has changed - this context is invalid. Use the
default behavior. */
unordered_remove (inline_states, state_it);
return nullptr;
}
return &state;
}
/* See inline-frame.h. */
void
clear_inline_frame_state (process_stratum_target *target, ptid_t filter_ptid)
{
gdb_assert (target != NULL);
if (filter_ptid == minus_one_ptid || filter_ptid.is_pid ())
{
auto matcher = [target, &filter_ptid] (const inline_state &state)
{
thread_info *t = state.thread;
return (t->inf->process_target () == target
&& t->ptid.matches (filter_ptid));
};
auto it = std::remove_if (inline_states.begin (), inline_states.end (),
matcher);
inline_states.erase (it, inline_states.end ());
return;
}
auto matcher = [target, &filter_ptid] (const inline_state &state)
{
thread_info *t = state.thread;
return (t->inf->process_target () == target
&& filter_ptid == t->ptid);
};
auto it = std::find_if (inline_states.begin (), inline_states.end (),
matcher);
if (it != inline_states.end ())
unordered_remove (inline_states, it);
}
/* See inline-frame.h. */
void
clear_inline_frame_state (thread_info *thread)
{
auto it = std::find_if (inline_states.begin (), inline_states.end (),
[thread] (const inline_state &state)
{
return thread == state.thread;
});
if (it != inline_states.end ())
unordered_remove (inline_states, it);
}
static void
inline_frame_this_id (const frame_info_ptr &this_frame,
void **this_cache,
struct frame_id *this_id)
{
struct symbol *func;
/* In order to have a stable frame ID for a given inline function,
we must get the stack / special addresses from the underlying
real frame's this_id method. So we must call
get_prev_frame_always. Because we are inlined into some
function, there must be previous frames, so this is safe - as
long as we're careful not to create any cycles. See related
comments in get_prev_frame_always_1. */
frame_info_ptr prev_frame = get_prev_frame_always (this_frame);
if (prev_frame == nullptr)
error (_("failed to find previous frame when computing inline frame id"));
*this_id = get_frame_id (prev_frame);
/* We need a valid frame ID, so we need to be based on a valid
frame. FSF submission NOTE: this would be a good assertion to
apply to all frames, all the time. That would fix the ambiguity
of null_frame_id (between "no/any frame" and "the outermost
frame"). This will take work. */
gdb_assert (frame_id_p (*this_id));
/* Future work NOTE: Alexandre Oliva applied a patch to GCC 4.3
which generates DW_AT_entry_pc for inlined functions when
possible. If this attribute is available, we should use it
in the frame ID (and eventually, to set breakpoints). */
func = get_frame_function (this_frame);
gdb_assert (func != NULL);
(*this_id).code_addr = func->value_block ()->entry_pc ();
(*this_id).artificial_depth++;
}
static struct value *
inline_frame_prev_register (const frame_info_ptr &this_frame, void **this_cache,
int regnum)
{
/* Use get_frame_register_value instead of
frame_unwind_got_register, to avoid requiring this frame's ID.
This frame's ID depends on the previous frame's ID (unusual), and
the previous frame's ID depends on this frame's unwound
registers. If unwinding registers from this frame called
get_frame_id, there would be a loop.
Do not copy this code into any other unwinder! Inlined functions
are special; other unwinders must not have a dependency on the
previous frame's ID, and therefore can and should use
frame_unwind_got_register instead. */
return get_frame_register_value (this_frame, regnum);
}
/* Check whether we are at an inlining site that does not already
have an associated frame. */
static int
inline_frame_sniffer (const struct frame_unwind *self,
const frame_info_ptr &this_frame,
void **this_cache)
{
CORE_ADDR this_pc;
const struct block *frame_block, *cur_block;
int depth;
frame_info_ptr next_frame;
struct inline_state *state = find_inline_frame_state (inferior_thread ());
this_pc = get_frame_address_in_block (this_frame);
frame_block = block_for_pc (this_pc);
if (frame_block == NULL)
return 0;
/* Calculate DEPTH, the number of inlined functions at this
location. */
depth = 0;
cur_block = frame_block;
while (cur_block->superblock ())
{
if (cur_block->inlined_p ())
depth++;
else if (cur_block->function () != NULL)
break;
cur_block = cur_block->superblock ();
}
/* Check how many inlined functions already have frames. */
for (next_frame = get_next_frame (this_frame);
next_frame && get_frame_type (next_frame) == INLINE_FRAME;
next_frame = get_next_frame (next_frame))
{
gdb_assert (depth > 0);
depth--;
}
/* If this is the topmost frame, or all frames above us are inlined,
then check whether we were requested to skip some frames (so they
can be stepped into later). */
if (state != NULL && state->skipped_frames > 0 && next_frame == NULL)
{
gdb_assert (depth >= state->skipped_frames);
depth -= state->skipped_frames;
}
/* If all the inlined functions here already have frames, then pass
to the normal unwinder for this PC. */
if (depth == 0)
return 0;
/* If the next frame is an inlined function, but not the outermost, then
we are the next outer. If it is not an inlined function, then we
are the innermost inlined function of a different real frame. */
return 1;
}
const struct frame_unwind inline_frame_unwind = {
"inline",
INLINE_FRAME,
default_frame_unwind_stop_reason,
inline_frame_this_id,
inline_frame_prev_register,
NULL,
inline_frame_sniffer
};
/* Return non-zero if BLOCK, an inlined function block containing PC,
has a group of contiguous instructions starting at PC (but not
before it). */
static int
block_starting_point_at (CORE_ADDR pc, const struct block *block)
{
const struct blockvector *bv;
const struct block *new_block;
bv = blockvector_for_pc (pc, NULL);
if (bv->map () == nullptr)
return 0;
new_block = (const struct block *) bv->map ()->find (pc - 1);
if (new_block == NULL)
return 1;
if (new_block == block || block->contains (new_block))
return 0;
/* The immediately preceding address belongs to a different block,
which is not a child of this one. Treat this as an entrance into
BLOCK. */
return 1;
}
/* Loop over the stop chain and determine if execution stopped in an
inlined frame because of a breakpoint with a user-specified location
set at FRAME_SYMBOL. */
static bool
stopped_by_user_bp_inline_frame (const symbol *frame_symbol,
bpstat *stop_chain)
{
for (bpstat *s = stop_chain; s != nullptr; s = s->next)
{
struct breakpoint *bpt = s->breakpoint_at;
if (bpt != NULL
&& (user_breakpoint_p (bpt) || bpt->type == bp_until))
{
bp_location *loc = s->bp_location_at.get ();
enum bp_loc_type t = loc->loc_type;
if (t == bp_loc_software_breakpoint
|| t == bp_loc_hardware_breakpoint)
{
/* If the location has a function symbol, check whether
the frame was for that inlined function. If it has
no function symbol, then assume it is. I.e., default
to presenting the stop at the innermost inline
function. */
if (loc->symbol == nullptr
|| frame_symbol == loc->symbol)
return true;
}
}
}
return false;
}
/* Return a list of all the inline function symbols that start at THIS_PC
and the symbol for the function which contains all of the inline
functions.
The function symbols are ordered such that the most inner function is
first.
The returned list can be empty if there are no function at THIS_PC. Or
the returned list may have only a single entry if there are no inline
functions starting at THIS_PC. */
static std::vector<const symbol *>
gather_inline_frames (CORE_ADDR this_pc)
{
/* Build the list of inline frames starting at THIS_PC. After the loop,
CUR_BLOCK is expected to point at the first function symbol (inlined or
not) "containing" the inline frames starting at THIS_PC. */
const block *cur_block = block_for_pc (this_pc);
if (cur_block == nullptr)
return {};
std::vector<const symbol *> function_symbols;
while (cur_block != nullptr)
{
if (cur_block->inlined_p ())
{
gdb_assert (cur_block->function () != nullptr);
/* See comments in inline_frame_this_id about this use
of BLOCK_ENTRY_PC. */
if (cur_block->entry_pc () == this_pc
|| block_starting_point_at (this_pc, cur_block))
function_symbols.push_back (cur_block->function ());
else
break;
}
else if (cur_block->function () != nullptr)
break;
cur_block = cur_block->superblock ();
}
/* If we have a code region for which we have no function blocks,
possibly due to bad debug, or possibly just when some debug
information has been stripped, then we can end up in a situation where
there are global and static blocks for an address, but no function
blocks. In this case the early return above will not trigger as we
will find the static block for THIS_PC, but in the loop above we will
fail to find any function blocks (inline or non-inline) and so
CUR_BLOCK will eventually become NULL. If this happens then
FUNCTION_SYMBOLS must be empty (as we found no function blocks).
Otherwise, if we did find a function block, then we should only leave
the above loop when CUR_BLOCK is pointing to a non-inline function
that possibly contains some inline functions, or CUR_BLOCK should
point to an inline function that doesn't start at THIS_PC. */
if (cur_block != nullptr)
{
gdb_assert (cur_block->function () != nullptr);
function_symbols.push_back (cur_block->function ());
}
else
gdb_assert (function_symbols.empty ());
return function_symbols;
}
/* See inline-frame.h. */
void
skip_inline_frames (thread_info *thread, bpstat *stop_chain)
{
gdb_assert (find_inline_frame_state (thread) == nullptr);
CORE_ADDR this_pc = get_frame_pc (get_current_frame ());
std::vector<const symbol *> function_symbols
= gather_inline_frames (this_pc);
/* Figure out how many of the inlined frames to skip. Do not skip an
inlined frame (and its callers) if execution stopped because of a user
breakpoint for this specific function.
By default, skip all the found inlined frames.
The last entry in FUNCTION_SYMBOLS is special, this is the function
which contains all of the inlined functions, we never skip this. */
int skipped_frames = 0;
for (const auto sym : function_symbols)
{
if (stopped_by_user_bp_inline_frame (sym, stop_chain)
|| sym == function_symbols.back ())
break;
++skipped_frames;
}
if (skipped_frames > 0)
reinit_frame_cache ();
inline_states.emplace_back (thread, skipped_frames, this_pc,
std::move (function_symbols));
}
/* Step into an inlined function by unhiding it. */
void
step_into_inline_frame (thread_info *thread)
{
inline_state *state = find_inline_frame_state (thread);
gdb_assert (state != NULL && state->skipped_frames > 0);
state->skipped_frames--;
reinit_frame_cache ();
}
/* Return the number of hidden functions inlined into the current
frame. */
int
inline_skipped_frames (thread_info *thread)
{
inline_state *state = find_inline_frame_state (thread);
if (state == NULL)
return 0;
else
return state->skipped_frames;
}
/* If one or more inlined functions are hidden, return the symbol for
the function inlined into the current frame. */
const symbol *
inline_skipped_symbol (thread_info *thread)
{
inline_state *state = find_inline_frame_state (thread);
gdb_assert (state != NULL);
/* This should only be called when we are skipping at least one frame,
hence FUNCTION_SYMBOLS will contain more than one entry (the last
entry is the "outer" containing function).
As we initialise SKIPPED_FRAMES at the same time as we build
FUNCTION_SYMBOLS it should be true that SKIPPED_FRAMES never indexes
outside of the FUNCTION_SYMBOLS vector. */
gdb_assert (state->function_symbols.size () > 1);
gdb_assert (state->skipped_frames > 0);
gdb_assert (state->skipped_frames < state->function_symbols.size ());
return state->function_symbols[state->skipped_frames - 1];
}
/* Return the number of functions inlined into THIS_FRAME. Some of
the callees may not have associated frames (see
skip_inline_frames). */
int
frame_inlined_callees (const frame_info_ptr &this_frame)
{
frame_info_ptr next_frame;
int inline_count = 0;
/* First count how many inlined functions at this PC have frames
above FRAME (are inlined into FRAME). */
for (next_frame = get_next_frame (this_frame);
next_frame && get_frame_type (next_frame) == INLINE_FRAME;
next_frame = get_next_frame (next_frame))
inline_count++;
/* Simulate some most-inner inlined frames which were suppressed, so
they can be stepped into later. If we are unwinding already
outer frames from some non-inlined frame this does not apply. */
if (next_frame == NULL)
inline_count += inline_skipped_frames (inferior_thread ());
return inline_count;
}
/* The 'maint info inline-frames' command. Takes an optional address
expression and displays inline frames that start at the given address,
or at the address of the current thread if no address is given. */
static void
maintenance_info_inline_frames (const char *arg, int from_tty)
{
std::optional<std::vector<const symbol *>> local_function_symbols;
std::vector<const symbol *> *function_symbols;
int skipped_frames;
CORE_ADDR addr;
if (arg == nullptr)
{
/* With no argument then the user wants to know about the current
inline frame information. This information is cached per-thread
and can be updated as the user steps between inline functions at
the current address. */
if (inferior_ptid == null_ptid)
error (_("no inferior thread"));
thread_info *thread = inferior_thread ();
auto it = std::find_if (inline_states.begin (), inline_states.end (),
[thread] (const inline_state &istate)
{
return thread == istate.thread;
});
/* Stopped threads always have cached inline_state information. */
gdb_assert (it != inline_states.end ());
gdb_printf (_("Cached inline state information for thread %s.\n"),
print_thread_id (thread));
function_symbols = &it->function_symbols;
skipped_frames = it->skipped_frames;
addr = it->saved_pc;
}
else
{
/* If there is an argument then parse it as an address, the user is
asking about inline functions that start at the given address. */
addr = parse_and_eval_address (arg);
local_function_symbols.emplace (gather_inline_frames (addr));
function_symbols = &(local_function_symbols.value ());
skipped_frames = function_symbols->size () - 1;
}
/* The address we're analysing. */
gdb_printf (_("program counter = %ps\n"),
styled_string (address_style.style (),
core_addr_to_string_nz (addr)));
gdb_printf (_("skipped frames = %d\n"), skipped_frames);
/* Print the full list of function symbols in STATE. Highlight the
current function as indicated by the skipped frames counter. */
for (size_t i = 0; i < function_symbols->size (); ++i)
gdb_printf (_("%c %ps\n"),
(i == skipped_frames ? '>' : ' '),
styled_string (function_name_style.style (),
(*function_symbols)[i]->print_name ()));
}
void _initialize_inline_frame ();
void
_initialize_inline_frame ()
{
add_cmd ("inline-frames", class_maintenance, maintenance_info_inline_frames,
_("\
Display inline frame information for current thread.\n\
\n\
Usage:\n\
\n\
maintenance info inline-frames [ADDRESS]\n\
\n\
With no ADDRESS show all inline frames starting at the current program\n\
counter address. When ADDRESS is given, list all inline frames starting\n\
at ADDRESS.\n\
\n\
The last frame listed might not start at ADDRESS, this is the frame that\n\
contains the other inline frames."),
&maintenanceinfolist);
}