mirror of
https://sourceware.org/git/binutils-gdb.git
synced 2024-12-09 04:21:49 +08:00
492d29ea1c
This patch splits the TRY_CATCH macro into three, so that we go from this: ~~~ volatile gdb_exception ex; TRY_CATCH (ex, RETURN_MASK_ERROR) { } if (ex.reason < 0) { } ~~~ to this: ~~~ TRY { } CATCH (ex, RETURN_MASK_ERROR) { } END_CATCH ~~~ Thus, we'll be getting rid of the local volatile exception object, and declaring the caught exception in the catch block. This allows reimplementing TRY/CATCH in terms of C++ exceptions when building in C++ mode, while still allowing to build GDB in C mode (using setjmp/longjmp), as a transition step. TBC, after this patch, is it _not_ valid to have code between the TRY and the CATCH blocks, like: TRY { } // some code here. CATCH (ex, RETURN_MASK_ERROR) { } END_CATCH Just like it isn't valid to do that with C++'s native try/catch. By switching to creating the exception object inside the CATCH block scope, we can get rid of all the explicitly allocated volatile exception objects all over the tree, and map the CATCH block more directly to C++'s catch blocks. The majority of the TRY_CATCH -> TRY+CATCH+END_CATCH conversion was done with a script, rerun from scratch at every rebase, no manual editing involved. After the mechanical conversion, a few places needed manual intervention, to fix preexisting cases where we were using the exception object outside of the TRY_CATCH block, and cases where we were using "else" after a 'if (ex.reason) < 0)' [a CATCH after this patch]. The result was folded into this patch so that GDB still builds at each incremental step. END_CATCH is necessary for two reasons: First, because we name the exception object in the CATCH block, which requires creating a scope, which in turn must be closed somewhere. Declaring the exception variable in the initializer field of a for block, like: #define CATCH(EXCEPTION, mask) \ for (struct gdb_exception EXCEPTION; \ exceptions_state_mc_catch (&EXCEPTION, MASK); \ EXCEPTION = exception_none) would avoid needing END_CATCH, but alas, in C mode, we build with C90, which doesn't allow mixed declarations and code. Second, because when TRY/CATCH are wired to real C++ try/catch, as long as we need to handle cleanup chains, even if there's no CATCH block that wants to catch the exception, we need for stop at every frame in the unwind chain and run cleanups, then rethrow. That will be done in END_CATCH. After we require C++, we'll still need TRY/CATCH/END_CATCH until cleanups are completely phased out -- TRY/CATCH in C++ mode will save/restore the current cleanup chain, like in C mode, and END_CATCH catches otherwise uncaugh exceptions, runs cleanups and rethrows, so that C++ cleanups and exceptions can coexist. IMO, this still makes the TRY/CATCH code look a bit more like a newcomer would expect, so IMO worth it even if we weren't considering C++. gdb/ChangeLog. 2015-03-07 Pedro Alves <palves@redhat.com> * common/common-exceptions.c (struct catcher) <exception>: No longer a pointer to volatile exception. Now an exception value. <mask>: Delete field. (exceptions_state_mc_init): Remove all parameters. Adjust. (exceptions_state_mc): No longer pop the catcher here. (exceptions_state_mc_catch): New function. (throw_exception): Adjust. * common/common-exceptions.h (exceptions_state_mc_init): Remove all parameters. (exceptions_state_mc_catch): Declare. (TRY_CATCH): Rename to ... (TRY): ... this. Remove EXCEPTION and MASK parameters. (CATCH, END_CATCH): New. All callers adjusted. gdb/gdbserver/ChangeLog: 2015-03-07 Pedro Alves <palves@redhat.com> Adjust all callers of TRY_CATCH to use TRY/CATCH/END_CATCH instead.
476 lines
13 KiB
C
476 lines
13 KiB
C
/* Virtual tail call frames unwinder for GDB.
|
|
|
|
Copyright (C) 2010-2015 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 "frame.h"
|
|
#include "dwarf2-frame-tailcall.h"
|
|
#include "dwarf2loc.h"
|
|
#include "frame-unwind.h"
|
|
#include "block.h"
|
|
#include "hashtab.h"
|
|
#include "gdbtypes.h"
|
|
#include "regcache.h"
|
|
#include "value.h"
|
|
#include "dwarf2-frame.h"
|
|
|
|
/* Contains struct tailcall_cache indexed by next_bottom_frame. */
|
|
static htab_t cache_htab;
|
|
|
|
/* Associate structure of the unwinder to call_site_chain. Lifetime of this
|
|
structure is maintained by REFC decremented by dealloc_cache, all of them
|
|
get deleted during reinit_frame_cache. */
|
|
struct tailcall_cache
|
|
{
|
|
/* It must be the first one of this struct. It is the furthest callee. */
|
|
struct frame_info *next_bottom_frame;
|
|
|
|
/* Reference count. The whole chain of virtual tail call frames shares one
|
|
tailcall_cache. */
|
|
int refc;
|
|
|
|
/* Associated found virtual taill call frames chain, it is never NULL. */
|
|
struct call_site_chain *chain;
|
|
|
|
/* Cached pretended_chain_levels result. */
|
|
int chain_levels;
|
|
|
|
/* Unwound PC from the top (caller) frame, as it is not contained
|
|
in CHAIN. */
|
|
CORE_ADDR prev_pc;
|
|
|
|
/* Compensate SP in caller frames appropriately. prev_sp and
|
|
entry_cfa_sp_offset are valid only if PREV_SP_P. PREV_SP is SP at the top
|
|
(caller) frame. ENTRY_CFA_SP_OFFSET is shift of SP in tail call frames
|
|
against next_bottom_frame SP. */
|
|
unsigned prev_sp_p : 1;
|
|
CORE_ADDR prev_sp;
|
|
LONGEST entry_cfa_sp_offset;
|
|
};
|
|
|
|
/* hash_f for htab_create_alloc of cache_htab. */
|
|
|
|
static hashval_t
|
|
cache_hash (const void *arg)
|
|
{
|
|
const struct tailcall_cache *cache = arg;
|
|
|
|
return htab_hash_pointer (cache->next_bottom_frame);
|
|
}
|
|
|
|
/* eq_f for htab_create_alloc of cache_htab. */
|
|
|
|
static int
|
|
cache_eq (const void *arg1, const void *arg2)
|
|
{
|
|
const struct tailcall_cache *cache1 = arg1;
|
|
const struct tailcall_cache *cache2 = arg2;
|
|
|
|
return cache1->next_bottom_frame == cache2->next_bottom_frame;
|
|
}
|
|
|
|
/* Create new tailcall_cache for NEXT_BOTTOM_FRAME, NEXT_BOTTOM_FRAME must not
|
|
yet have been indexed by cache_htab. Caller holds one reference of the new
|
|
tailcall_cache. */
|
|
|
|
static struct tailcall_cache *
|
|
cache_new_ref1 (struct frame_info *next_bottom_frame)
|
|
{
|
|
struct tailcall_cache *cache;
|
|
void **slot;
|
|
|
|
cache = xzalloc (sizeof (*cache));
|
|
|
|
cache->next_bottom_frame = next_bottom_frame;
|
|
cache->refc = 1;
|
|
|
|
slot = htab_find_slot (cache_htab, cache, INSERT);
|
|
gdb_assert (*slot == NULL);
|
|
*slot = cache;
|
|
|
|
return cache;
|
|
}
|
|
|
|
/* Create new reference to CACHE. */
|
|
|
|
static void
|
|
cache_ref (struct tailcall_cache *cache)
|
|
{
|
|
gdb_assert (cache->refc > 0);
|
|
|
|
cache->refc++;
|
|
}
|
|
|
|
/* Drop reference to CACHE, possibly fully freeing it and unregistering it from
|
|
cache_htab. */
|
|
|
|
static void
|
|
cache_unref (struct tailcall_cache *cache)
|
|
{
|
|
gdb_assert (cache->refc > 0);
|
|
|
|
if (!--cache->refc)
|
|
{
|
|
gdb_assert (htab_find_slot (cache_htab, cache, NO_INSERT) != NULL);
|
|
htab_remove_elt (cache_htab, cache);
|
|
|
|
xfree (cache->chain);
|
|
xfree (cache);
|
|
}
|
|
}
|
|
|
|
/* Return 1 if FI is a non-bottom (not the callee) tail call frame. Otherwise
|
|
return 0. */
|
|
|
|
static int
|
|
frame_is_tailcall (struct frame_info *fi)
|
|
{
|
|
return frame_unwinder_is (fi, &dwarf2_tailcall_frame_unwind);
|
|
}
|
|
|
|
/* Try to find tailcall_cache in cache_htab if FI is a part of its virtual tail
|
|
call chain. Otherwise return NULL. No new reference is created. */
|
|
|
|
static struct tailcall_cache *
|
|
cache_find (struct frame_info *fi)
|
|
{
|
|
struct tailcall_cache *cache;
|
|
void **slot;
|
|
|
|
while (frame_is_tailcall (fi))
|
|
{
|
|
fi = get_next_frame (fi);
|
|
gdb_assert (fi != NULL);
|
|
}
|
|
|
|
slot = htab_find_slot (cache_htab, &fi, NO_INSERT);
|
|
if (slot == NULL)
|
|
return NULL;
|
|
|
|
cache = *slot;
|
|
gdb_assert (cache != NULL);
|
|
return cache;
|
|
}
|
|
|
|
/* Number of virtual frames between THIS_FRAME and CACHE->NEXT_BOTTOM_FRAME.
|
|
If THIS_FRAME is CACHE-> NEXT_BOTTOM_FRAME return -1. */
|
|
|
|
static int
|
|
existing_next_levels (struct frame_info *this_frame,
|
|
struct tailcall_cache *cache)
|
|
{
|
|
int retval = (frame_relative_level (this_frame)
|
|
- frame_relative_level (cache->next_bottom_frame) - 1);
|
|
|
|
gdb_assert (retval >= -1);
|
|
|
|
return retval;
|
|
}
|
|
|
|
/* The number of virtual tail call frames in CHAIN. With no virtual tail call
|
|
frames the function would return 0 (but CHAIN does not exist in such
|
|
case). */
|
|
|
|
static int
|
|
pretended_chain_levels (struct call_site_chain *chain)
|
|
{
|
|
int chain_levels;
|
|
|
|
gdb_assert (chain != NULL);
|
|
|
|
if (chain->callers == chain->length && chain->callees == chain->length)
|
|
return chain->length;
|
|
|
|
chain_levels = chain->callers + chain->callees;
|
|
gdb_assert (chain_levels < chain->length);
|
|
|
|
return chain_levels;
|
|
}
|
|
|
|
/* Implementation of frame_this_id_ftype. THIS_CACHE must be already
|
|
initialized with tailcall_cache, THIS_FRAME must be a part of THIS_CACHE.
|
|
|
|
Specific virtual tail call frames are tracked by INLINE_DEPTH. */
|
|
|
|
static void
|
|
tailcall_frame_this_id (struct frame_info *this_frame, void **this_cache,
|
|
struct frame_id *this_id)
|
|
{
|
|
struct tailcall_cache *cache = *this_cache;
|
|
struct frame_info *next_frame;
|
|
|
|
/* Tail call does not make sense for a sentinel frame. */
|
|
next_frame = get_next_frame (this_frame);
|
|
gdb_assert (next_frame != NULL);
|
|
|
|
*this_id = get_frame_id (next_frame);
|
|
(*this_id).code_addr = get_frame_pc (this_frame);
|
|
(*this_id).code_addr_p = 1;
|
|
(*this_id).artificial_depth = (cache->chain_levels
|
|
- existing_next_levels (this_frame, cache));
|
|
gdb_assert ((*this_id).artificial_depth > 0);
|
|
}
|
|
|
|
/* Find PC to be unwound from THIS_FRAME. THIS_FRAME must be a part of
|
|
CACHE. */
|
|
|
|
static CORE_ADDR
|
|
pretend_pc (struct frame_info *this_frame, struct tailcall_cache *cache)
|
|
{
|
|
int next_levels = existing_next_levels (this_frame, cache);
|
|
struct call_site_chain *chain = cache->chain;
|
|
|
|
gdb_assert (chain != NULL);
|
|
|
|
next_levels++;
|
|
gdb_assert (next_levels >= 0);
|
|
|
|
if (next_levels < chain->callees)
|
|
return chain->call_site[chain->length - next_levels - 1]->pc;
|
|
next_levels -= chain->callees;
|
|
|
|
/* Otherwise CHAIN->CALLEES are already covered by CHAIN->CALLERS. */
|
|
if (chain->callees != chain->length)
|
|
{
|
|
if (next_levels < chain->callers)
|
|
return chain->call_site[chain->callers - next_levels - 1]->pc;
|
|
next_levels -= chain->callers;
|
|
}
|
|
|
|
gdb_assert (next_levels == 0);
|
|
return cache->prev_pc;
|
|
}
|
|
|
|
/* Implementation of frame_prev_register_ftype. If no specific register
|
|
override is supplied NULL is returned (this is incompatible with
|
|
frame_prev_register_ftype semantics). next_bottom_frame and tail call
|
|
frames unwind the NULL case differently. */
|
|
|
|
struct value *
|
|
dwarf2_tailcall_prev_register_first (struct frame_info *this_frame,
|
|
void **tailcall_cachep, int regnum)
|
|
{
|
|
struct gdbarch *this_gdbarch = get_frame_arch (this_frame);
|
|
struct tailcall_cache *cache = *tailcall_cachep;
|
|
CORE_ADDR addr;
|
|
|
|
if (regnum == gdbarch_pc_regnum (this_gdbarch))
|
|
addr = pretend_pc (this_frame, cache);
|
|
else if (cache->prev_sp_p && regnum == gdbarch_sp_regnum (this_gdbarch))
|
|
{
|
|
int next_levels = existing_next_levels (this_frame, cache);
|
|
|
|
if (next_levels == cache->chain_levels - 1)
|
|
addr = cache->prev_sp;
|
|
else
|
|
addr = dwarf2_frame_cfa (this_frame) - cache->entry_cfa_sp_offset;
|
|
}
|
|
else
|
|
return NULL;
|
|
|
|
return frame_unwind_got_address (this_frame, regnum, addr);
|
|
}
|
|
|
|
/* Implementation of frame_prev_register_ftype for tail call frames. Register
|
|
set of virtual tail call frames is assumed to be the one of the top (caller)
|
|
frame - assume unchanged register value for NULL from
|
|
dwarf2_tailcall_prev_register_first. */
|
|
|
|
static struct value *
|
|
tailcall_frame_prev_register (struct frame_info *this_frame,
|
|
void **this_cache, int regnum)
|
|
{
|
|
struct tailcall_cache *cache = *this_cache;
|
|
struct value *val;
|
|
|
|
gdb_assert (this_frame != cache->next_bottom_frame);
|
|
|
|
val = dwarf2_tailcall_prev_register_first (this_frame, this_cache, regnum);
|
|
if (val)
|
|
return val;
|
|
|
|
return frame_unwind_got_register (this_frame, regnum, regnum);
|
|
}
|
|
|
|
/* Implementation of frame_sniffer_ftype. It will never find a new chain, use
|
|
dwarf2_tailcall_sniffer_first for the bottom (callee) frame. It will find
|
|
all the predecessing virtual tail call frames, it will return false when
|
|
there exist no more tail call frames in this chain. */
|
|
|
|
static int
|
|
tailcall_frame_sniffer (const struct frame_unwind *self,
|
|
struct frame_info *this_frame, void **this_cache)
|
|
{
|
|
struct frame_info *next_frame;
|
|
int next_levels;
|
|
struct tailcall_cache *cache;
|
|
|
|
/* Inner tail call element does not make sense for a sentinel frame. */
|
|
next_frame = get_next_frame (this_frame);
|
|
if (next_frame == NULL)
|
|
return 0;
|
|
|
|
cache = cache_find (next_frame);
|
|
if (cache == NULL)
|
|
return 0;
|
|
|
|
cache_ref (cache);
|
|
|
|
next_levels = existing_next_levels (this_frame, cache);
|
|
|
|
/* NEXT_LEVELS is -1 only in dwarf2_tailcall_sniffer_first. */
|
|
gdb_assert (next_levels >= 0);
|
|
gdb_assert (next_levels <= cache->chain_levels);
|
|
|
|
if (next_levels == cache->chain_levels)
|
|
{
|
|
cache_unref (cache);
|
|
return 0;
|
|
}
|
|
|
|
*this_cache = cache;
|
|
return 1;
|
|
}
|
|
|
|
/* The initial "sniffer" whether THIS_FRAME is a bottom (callee) frame of a new
|
|
chain to create. Keep TAILCALL_CACHEP NULL if it did not find any chain,
|
|
initialize it otherwise. No tail call chain is created if there are no
|
|
unambiguous virtual tail call frames to report.
|
|
|
|
ENTRY_CFA_SP_OFFSETP is NULL if no special SP handling is possible,
|
|
otherwise *ENTRY_CFA_SP_OFFSETP is the number of bytes to subtract from tail
|
|
call frames frame base to get the SP value there - to simulate return
|
|
address pushed on the stack. */
|
|
|
|
void
|
|
dwarf2_tailcall_sniffer_first (struct frame_info *this_frame,
|
|
void **tailcall_cachep,
|
|
const LONGEST *entry_cfa_sp_offsetp)
|
|
{
|
|
CORE_ADDR prev_pc = 0, prev_sp = 0; /* GCC warning. */
|
|
int prev_sp_p = 0;
|
|
CORE_ADDR this_pc;
|
|
struct gdbarch *prev_gdbarch;
|
|
struct call_site_chain *chain = NULL;
|
|
struct tailcall_cache *cache;
|
|
|
|
gdb_assert (*tailcall_cachep == NULL);
|
|
|
|
/* PC may be after the function if THIS_FRAME calls noreturn function,
|
|
get_frame_address_in_block will decrease it by 1 in such case. */
|
|
this_pc = get_frame_address_in_block (this_frame);
|
|
|
|
/* Catch any unwinding errors. */
|
|
TRY
|
|
{
|
|
int sp_regnum;
|
|
|
|
prev_gdbarch = frame_unwind_arch (this_frame);
|
|
|
|
/* Simulate frame_unwind_pc without setting this_frame->prev_pc.p. */
|
|
prev_pc = gdbarch_unwind_pc (prev_gdbarch, this_frame);
|
|
|
|
/* call_site_find_chain can throw an exception. */
|
|
chain = call_site_find_chain (prev_gdbarch, prev_pc, this_pc);
|
|
|
|
if (entry_cfa_sp_offsetp == NULL)
|
|
break;
|
|
sp_regnum = gdbarch_sp_regnum (prev_gdbarch);
|
|
if (sp_regnum == -1)
|
|
break;
|
|
prev_sp = frame_unwind_register_unsigned (this_frame, sp_regnum);
|
|
prev_sp_p = 1;
|
|
}
|
|
CATCH (except, RETURN_MASK_ERROR)
|
|
{
|
|
if (entry_values_debug)
|
|
exception_print (gdb_stdout, except);
|
|
return;
|
|
}
|
|
END_CATCH
|
|
|
|
/* Ambiguous unwind or unambiguous unwind verified as matching. */
|
|
if (chain == NULL || chain->length == 0)
|
|
{
|
|
xfree (chain);
|
|
return;
|
|
}
|
|
|
|
cache = cache_new_ref1 (this_frame);
|
|
*tailcall_cachep = cache;
|
|
cache->chain = chain;
|
|
cache->prev_pc = prev_pc;
|
|
cache->chain_levels = pretended_chain_levels (chain);
|
|
cache->prev_sp_p = prev_sp_p;
|
|
if (cache->prev_sp_p)
|
|
{
|
|
cache->prev_sp = prev_sp;
|
|
cache->entry_cfa_sp_offset = *entry_cfa_sp_offsetp;
|
|
}
|
|
gdb_assert (cache->chain_levels > 0);
|
|
}
|
|
|
|
/* Implementation of frame_dealloc_cache_ftype. It can be called even for the
|
|
bottom chain frame from dwarf2_frame_dealloc_cache which is not a real
|
|
TAILCALL_FRAME. */
|
|
|
|
static void
|
|
tailcall_frame_dealloc_cache (struct frame_info *self, void *this_cache)
|
|
{
|
|
struct tailcall_cache *cache = this_cache;
|
|
|
|
cache_unref (cache);
|
|
}
|
|
|
|
/* Implementation of frame_prev_arch_ftype. We assume all the virtual tail
|
|
call frames have gdbarch of the bottom (callee) frame. */
|
|
|
|
static struct gdbarch *
|
|
tailcall_frame_prev_arch (struct frame_info *this_frame,
|
|
void **this_prologue_cache)
|
|
{
|
|
struct tailcall_cache *cache = *this_prologue_cache;
|
|
|
|
return get_frame_arch (cache->next_bottom_frame);
|
|
}
|
|
|
|
/* Virtual tail call frame unwinder if dwarf2_tailcall_sniffer_first finds
|
|
a chain to create. */
|
|
|
|
const struct frame_unwind dwarf2_tailcall_frame_unwind =
|
|
{
|
|
TAILCALL_FRAME,
|
|
default_frame_unwind_stop_reason,
|
|
tailcall_frame_this_id,
|
|
tailcall_frame_prev_register,
|
|
NULL,
|
|
tailcall_frame_sniffer,
|
|
tailcall_frame_dealloc_cache,
|
|
tailcall_frame_prev_arch
|
|
};
|
|
|
|
/* Provide a prototype to silence -Wmissing-prototypes. */
|
|
extern initialize_file_ftype _initialize_tailcall_frame;
|
|
|
|
void
|
|
_initialize_tailcall_frame (void)
|
|
{
|
|
cache_htab = htab_create_alloc (50, cache_hash, cache_eq, NULL, xcalloc,
|
|
xfree);
|
|
}
|