/* 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 . */
#include "defs.h"
#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
/* 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 &&skipped_symbols_)
: thread (thread_), skipped_frames (skipped_frames_), saved_pc (saved_pc_),
skipped_symbols (std::move (skipped_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;
/* Only valid if SKIPPED_FRAMES is non-zero. This is the PC used
when calculating SKIPPED_FRAMES; 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;
/* Only valid if SKIPPED_FRAMES is non-zero. This is the list of all
function symbols that have been skipped, from inner most to outer
most. It is used to find the call site of the current frame. */
std::vector skipped_symbols;
};
static std::vector 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_BLOCK. */
static bool
stopped_by_user_bp_inline_frame (const block *frame_block, 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_block == loc->symbol->value_block ())
return true;
}
}
}
return false;
}
/* See inline-frame.h. */
void
skip_inline_frames (thread_info *thread, bpstat *stop_chain)
{
const struct block *frame_block, *cur_block;
std::vector skipped_syms;
int skip_count = 0;
/* This function is called right after reinitializing the frame
cache. We try not to do more unwinding than absolutely
necessary, for performance. */
CORE_ADDR this_pc = get_frame_pc (get_current_frame ());
frame_block = block_for_pc (this_pc);
if (frame_block != NULL)
{
cur_block = frame_block;
while (cur_block->superblock ())
{
if (cur_block->inlined_p ())
{
/* 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))
{
/* Do not skip the inlined frame if execution
stopped in an inlined frame because of a user
breakpoint for this inline function. */
if (stopped_by_user_bp_inline_frame (cur_block, stop_chain))
break;
skip_count++;
skipped_syms.push_back (cur_block->function ());
}
else
break;
}
else if (cur_block->function () != NULL)
break;
cur_block = cur_block->superblock ();
}
}
gdb_assert (find_inline_frame_state (thread) == NULL);
inline_states.emplace_back (thread, skip_count, this_pc,
std::move (skipped_syms));
if (skip_count != 0)
reinit_frame_cache ();
}
/* 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. */
struct 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 SKIPPED_FRAMES will be greater than zero when we get here.
We initialise SKIPPED_FRAMES at the same time as we build
SKIPPED_SYMBOLS, hence it should be true that SKIPPED_FRAMES never
indexes outside of the SKIPPED_SYMBOLS vector. */
gdb_assert (state->skipped_frames > 0);
gdb_assert (state->skipped_frames <= state->skipped_symbols.size ());
return state->skipped_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;
}