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btrace: Replace struct btrace_function::up.

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This used to hold a function segment pointer.  Change it to hold an index into
the vector of function segments instead.
This commit is contained in:
Tim Wiederhake
2017-05-30 12:47:37 +02:00
parent b54b03bd87
commit 42bfe59e3a
5 changed files with 130 additions and 64 deletions
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15
gdb/ChangeLog
View File

@ -1,3 +1,18 @@
2017-05-30 Tim Wiederhake <tim.wiederhake@intel.com>
* btrace.c (ftrace_find_call_by_number): New function.
(ftrace_update_caller, ftrace_new_call, ftrace_new_tailcall,
ftrace_get_caller, ftrace_find_call, ftrace_new_return,
ftrace_match_backtrace, ftrace_connect_bfun, ftrace_connect_backtrace,
ftrace_bridge_gap, btrace_bridge_gaps): Use btrace_function::up as an
index.
* btrace.h (struct btrace_function): Turn UP into an index.
* python/py-record-btrace.c (btpy_call_up): Use btrace_function::up
as an index.
* record-btrace.c (record_btrace_frame_unwind_stop_reason,
record_btrace_frame_prev_register, record_btrace_frame_sniffer,
record_btrace_tailcall_frame_sniffe): Use btrace_find_call_by_number.
2017-05-30 Tim Wiederhake <tim.wiederhake@intel.com>
* btrace.c (ftrace_new_function, ftrace_new_call, ftrace_new_tailcall,

141
gdb/btrace.c
View File

@ -156,6 +156,19 @@ ftrace_call_num_insn (const struct btrace_function* bfun)
return VEC_length (btrace_insn_s, bfun->insn);
}
/* Return the function segment with the given NUMBER or NULL if no such segment
exists. BTINFO is the branch trace information for the current thread. */
static struct btrace_function *
ftrace_find_call_by_number (const struct btrace_thread_info *btinfo,
unsigned int number)
{
if (number == 0 || number > btinfo->functions.size ())
return NULL;
return btinfo->functions[number - 1];
}
/* Return non-zero if BFUN does not match MFUN and FUN,
return zero otherwise. */
@ -249,10 +262,10 @@ ftrace_update_caller (struct btrace_function *bfun,
struct btrace_function *caller,
enum btrace_function_flag flags)
{
if (bfun->up != NULL)
if (bfun->up != 0)
ftrace_debug (bfun, "updating caller");
bfun->up = caller;
bfun->up = caller->number;
bfun->flags = flags;
ftrace_debug (bfun, "set caller");
@ -290,8 +303,7 @@ ftrace_new_call (struct btrace_thread_info *btinfo,
const unsigned int length = btinfo->functions.size ();
struct btrace_function *bfun = ftrace_new_function (btinfo, mfun, fun);
if (length != 0)
bfun->up = btinfo->functions[length - 1];
bfun->up = length;
bfun->level += 1;
ftrace_debug (bfun, "new call");
@ -311,8 +323,7 @@ ftrace_new_tailcall (struct btrace_thread_info *btinfo,
const unsigned int length = btinfo->functions.size ();
struct btrace_function *bfun = ftrace_new_function (btinfo, mfun, fun);
if (length != 0)
bfun->up = btinfo->functions[length - 1];
bfun->up = length;
bfun->level += 1;
bfun->flags |= BFUN_UP_LINKS_TO_TAILCALL;
@ -322,26 +333,30 @@ ftrace_new_tailcall (struct btrace_thread_info *btinfo,
}
/* Return the caller of BFUN or NULL if there is none. This function skips
tail calls in the call chain. */
tail calls in the call chain. BTINFO is the branch trace information for
the current thread. */
static struct btrace_function *
ftrace_get_caller (struct btrace_function *bfun)
ftrace_get_caller (struct btrace_thread_info *btinfo,
struct btrace_function *bfun)
{
for (; bfun != NULL; bfun = bfun->up)
for (; bfun != NULL; bfun = ftrace_find_call_by_number (btinfo, bfun->up))
if ((bfun->flags & BFUN_UP_LINKS_TO_TAILCALL) == 0)
return bfun->up;
return ftrace_find_call_by_number (btinfo, bfun->up);
return NULL;
}
/* Find the innermost caller in the back trace of BFUN with MFUN/FUN
symbol information. */
symbol information. BTINFO is the branch trace information for the current
thread. */
static struct btrace_function *
ftrace_find_caller (struct btrace_function *bfun,
ftrace_find_caller (struct btrace_thread_info *btinfo,
struct btrace_function *bfun,
struct minimal_symbol *mfun,
struct symbol *fun)
{
for (; bfun != NULL; bfun = bfun->up)
for (; bfun != NULL; bfun = ftrace_find_call_by_number (btinfo, bfun->up))
{
/* Skip functions with incompatible symbol information. */
if (ftrace_function_switched (bfun, mfun, fun))
@ -356,12 +371,14 @@ ftrace_find_caller (struct btrace_function *bfun,
/* Find the innermost caller in the back trace of BFUN, skipping all
function segments that do not end with a call instruction (e.g.
tail calls ending with a jump). */
tail calls ending with a jump). BTINFO is the branch trace information for
the current thread. */
static struct btrace_function *
ftrace_find_call (struct btrace_function *bfun)
ftrace_find_call (struct btrace_thread_info *btinfo,
struct btrace_function *bfun)
{
for (; bfun != NULL; bfun = bfun->up)
for (; bfun != NULL; bfun = ftrace_find_call_by_number (btinfo, bfun->up))
{
struct btrace_insn *last;
@ -395,7 +412,8 @@ ftrace_new_return (struct btrace_thread_info *btinfo,
/* It is important to start at PREV's caller. Otherwise, we might find
PREV itself, if PREV is a recursive function. */
caller = ftrace_find_caller (prev->up, mfun, fun);
caller = ftrace_find_call_by_number (btinfo, prev->up);
caller = ftrace_find_caller (btinfo, caller, mfun, fun);
if (caller != NULL)
{
/* The caller of PREV is the preceding btrace function segment in this
@ -420,7 +438,8 @@ ftrace_new_return (struct btrace_thread_info *btinfo,
wrong or that the call is simply not included in the trace. */
/* Let's search for some actual call. */
caller = ftrace_find_call (prev->up);
caller = ftrace_find_call_by_number (btinfo, prev->up);
caller = ftrace_find_call (btinfo, caller);
if (caller == NULL)
{
/* There is no call in PREV's back trace. We assume that the
@ -428,8 +447,8 @@ ftrace_new_return (struct btrace_thread_info *btinfo,
/* Let's find the topmost function and add a new caller for it.
This should handle a series of initial tail calls. */
while (prev->up != NULL)
prev = prev->up;
while (prev->up != 0)
prev = ftrace_find_call_by_number (btinfo, prev->up);
bfun->level = prev->level - 1;
@ -449,7 +468,7 @@ ftrace_new_return (struct btrace_thread_info *btinfo,
on the same level as they are.
This should handle things like schedule () correctly where we're
switching contexts. */
prev->up = bfun;
prev->up = bfun->number;
prev->flags = BFUN_UP_LINKS_TO_RET;
ftrace_debug (bfun, "new return - unknown caller");
@ -653,10 +672,11 @@ ftrace_classify_insn (struct gdbarch *gdbarch, CORE_ADDR pc)
/* Try to match the back trace at LHS to the back trace at RHS. Returns the
number of matching function segments or zero if the back traces do not
match. */
match. BTINFO is the branch trace information for the current thread. */
static int
ftrace_match_backtrace (struct btrace_function *lhs,
ftrace_match_backtrace (struct btrace_thread_info *btinfo,
struct btrace_function *lhs,
struct btrace_function *rhs)
{
int matches;
@ -666,8 +686,8 @@ ftrace_match_backtrace (struct btrace_function *lhs,
if (ftrace_function_switched (lhs, rhs->msym, rhs->sym))
return 0;
lhs = ftrace_get_caller (lhs);
rhs = ftrace_get_caller (rhs);
lhs = ftrace_get_caller (btinfo, lhs);
rhs = ftrace_get_caller (btinfo, rhs);
}
return matches;
@ -718,10 +738,12 @@ ftrace_compute_global_level_offset (struct btrace_thread_info *btinfo)
}
/* Connect the function segments PREV and NEXT in a bottom-to-top walk as in
ftrace_connect_backtrace. */
ftrace_connect_backtrace. BTINFO is the branch trace information for the
current thread. */
static void
ftrace_connect_bfun (struct btrace_function *prev,
ftrace_connect_bfun (struct btrace_thread_info *btinfo,
struct btrace_function *prev,
struct btrace_function *next)
{
DEBUG_FTRACE ("connecting...");
@ -739,20 +761,26 @@ ftrace_connect_bfun (struct btrace_function *prev,
ftrace_fixup_level (next, prev->level - next->level);
/* If we run out of back trace for one, let's use the other's. */
if (prev->up == NULL)
if (prev->up == 0)
{
if (next->up != NULL)
const btrace_function_flags flags = next->flags;
next = ftrace_find_call_by_number (btinfo, next->up);
if (next != NULL)
{
DEBUG_FTRACE ("using next's callers");
ftrace_fixup_caller (prev, next->up, next->flags);
ftrace_fixup_caller (prev, next, flags);
}
}
else if (next->up == NULL)
else if (next->up == 0)
{
if (prev->up != NULL)
const btrace_function_flags flags = prev->flags;
prev = ftrace_find_call_by_number (btinfo, prev->up);
if (prev != NULL)
{
DEBUG_FTRACE ("using prev's callers");
ftrace_fixup_caller (next, prev->up, prev->flags);
ftrace_fixup_caller (next, prev, flags);
}
}
else
@ -770,26 +798,29 @@ ftrace_connect_bfun (struct btrace_function *prev,
if ((prev->flags & BFUN_UP_LINKS_TO_TAILCALL) != 0)
{
struct btrace_function *caller;
btrace_function_flags flags;
btrace_function_flags next_flags, prev_flags;
/* We checked NEXT->UP above so CALLER can't be NULL. */
caller = next->up;
flags = next->flags;
caller = ftrace_find_call_by_number (btinfo, next->up);
next_flags = next->flags;
prev_flags = prev->flags;
DEBUG_FTRACE ("adding prev's tail calls to next");
ftrace_fixup_caller (next, prev->up, prev->flags);
prev = ftrace_find_call_by_number (btinfo, prev->up);
ftrace_fixup_caller (next, prev, prev_flags);
for (prev = prev->up; prev != NULL; prev = prev->up)
for (; prev != NULL; prev = ftrace_find_call_by_number (btinfo,
prev->up))
{
/* At the end of PREV's back trace, continue with CALLER. */
if (prev->up == NULL)
if (prev->up == 0)
{
DEBUG_FTRACE ("fixing up link for tailcall chain");
ftrace_debug (prev, "..top");
ftrace_debug (caller, "..up");
ftrace_fixup_caller (prev, caller, flags);
ftrace_fixup_caller (prev, caller, next_flags);
/* If we skipped any tail calls, this may move CALLER to a
different function level.
@ -817,10 +848,12 @@ ftrace_connect_bfun (struct btrace_function *prev,
/* Connect function segments on the same level in the back trace at LHS and RHS.
The back traces at LHS and RHS are expected to match according to
ftrace_match_backtrace. */
ftrace_match_backtrace. BTINFO is the branch trace information for the
current thread. */
static void
ftrace_connect_backtrace (struct btrace_function *lhs,
ftrace_connect_backtrace (struct btrace_thread_info *btinfo,
struct btrace_function *lhs,
struct btrace_function *rhs)
{
while (lhs != NULL && rhs != NULL)
@ -833,20 +866,22 @@ ftrace_connect_backtrace (struct btrace_function *lhs,
prev = lhs;
next = rhs;
lhs = ftrace_get_caller (lhs);
rhs = ftrace_get_caller (rhs);
lhs = ftrace_get_caller (btinfo, lhs);
rhs = ftrace_get_caller (btinfo, rhs);
ftrace_connect_bfun (prev, next);
ftrace_connect_bfun (btinfo, prev, next);
}
}
/* Bridge the gap between two function segments left and right of a gap if their
respective back traces match in at least MIN_MATCHES functions.
respective back traces match in at least MIN_MATCHES functions. BTINFO is
the branch trace information for the current thread.
Returns non-zero if the gap could be bridged, zero otherwise. */
static int
ftrace_bridge_gap (struct btrace_function *lhs, struct btrace_function *rhs,
ftrace_bridge_gap (struct btrace_thread_info *btinfo,
struct btrace_function *lhs, struct btrace_function *rhs,
int min_matches)
{
struct btrace_function *best_l, *best_r, *cand_l, *cand_r;
@ -862,12 +897,14 @@ ftrace_bridge_gap (struct btrace_function *lhs, struct btrace_function *rhs,
/* We search the back traces of LHS and RHS for valid connections and connect
the two functon segments that give the longest combined back trace. */
for (cand_l = lhs; cand_l != NULL; cand_l = ftrace_get_caller (cand_l))
for (cand_r = rhs; cand_r != NULL; cand_r = ftrace_get_caller (cand_r))
for (cand_l = lhs; cand_l != NULL;
cand_l = ftrace_get_caller (btinfo, cand_l))
for (cand_r = rhs; cand_r != NULL;
cand_r = ftrace_get_caller (btinfo, cand_r))
{
int matches;
matches = ftrace_match_backtrace (cand_l, cand_r);
matches = ftrace_match_backtrace (btinfo, cand_l, cand_r);
if (best_matches < matches)
{
best_matches = matches;
@ -894,7 +931,7 @@ ftrace_bridge_gap (struct btrace_function *lhs, struct btrace_function *rhs,
BEST_L to BEST_R as they will already be on the same level. */
ftrace_fixup_level (rhs, best_l->level - best_r->level);
ftrace_connect_backtrace (best_l, best_r);
ftrace_connect_backtrace (btinfo, best_l, best_r);
return best_matches;
}
@ -952,7 +989,7 @@ btrace_bridge_gaps (struct thread_info *tp, VEC (bfun_s) **gaps)
if (rhs == NULL)
continue;
bridged = ftrace_bridge_gap (lhs, rhs, min_matches);
bridged = ftrace_bridge_gap (&tp->btrace, lhs, rhs, min_matches);
/* Keep track of gaps we were not able to bridge and try again.
If we just pushed them to the end of GAPS we would risk an

6
gdb/btrace.h
View File

@ -154,8 +154,10 @@ struct btrace_function
/* The previous and next function in control flow order. */
struct btrace_func_link flow;
/* The directly preceding function segment in a (fake) call stack. */
struct btrace_function *up;
/* The function segment number of the directly preceding function segment in
a (fake) call stack. Will be zero if there is no such function segment in
the record. */
unsigned int up;
/* The instructions in this function segment.
The instruction vector will be empty if the function segment

4
gdb/python/py-record-btrace.c
View File

@ -398,11 +398,11 @@ recpy_bt_func_up (PyObject *self, void *closure)
if (func == NULL)
return NULL;
if (func->up == NULL)
if (func->up == 0)
Py_RETURN_NONE;
return recpy_func_new (((recpy_element_object *) self)->ptid,
RECORD_METHOD_BTRACE, func->up->number);
RECORD_METHOD_BTRACE, func->up);
}
/* Implementation of RecordFunctionSegment.prev [RecordFunctionSegment] for

28
gdb/record-btrace.c
View File

@ -1570,7 +1570,7 @@ record_btrace_frame_unwind_stop_reason (struct frame_info *this_frame,
bfun = cache->bfun;
gdb_assert (bfun != NULL);
if (bfun->up == NULL)
if (bfun->up == 0)
return UNWIND_UNAVAILABLE;
return UNWIND_NO_REASON;
@ -1615,6 +1615,7 @@ record_btrace_frame_prev_register (struct frame_info *this_frame,
const struct btrace_frame_cache *cache;
const struct btrace_function *bfun, *caller;
const struct btrace_insn *insn;
struct btrace_call_iterator it;
struct gdbarch *gdbarch;
CORE_ADDR pc;
int pcreg;
@ -1629,11 +1630,12 @@ record_btrace_frame_prev_register (struct frame_info *this_frame,
bfun = cache->bfun;
gdb_assert (bfun != NULL);
caller = bfun->up;
if (caller == NULL)
if (btrace_find_call_by_number (&it, &cache->tp->btrace, bfun->up) == 0)
throw_error (NOT_AVAILABLE_ERROR,
_("No caller in btrace record history"));
caller = btrace_call_get (&it);
if ((bfun->flags & BFUN_UP_LINKS_TO_RET) != 0)
{
insn = VEC_index (btrace_insn_s, caller->insn, 0);
@ -1683,10 +1685,16 @@ record_btrace_frame_sniffer (const struct frame_unwind *self,
else
{
const struct btrace_function *callee;
struct btrace_call_iterator it;
callee = btrace_get_frame_function (next);
if (callee != NULL && (callee->flags & BFUN_UP_LINKS_TO_TAILCALL) == 0)
bfun = callee->up;
if (callee == NULL || (callee->flags & BFUN_UP_LINKS_TO_TAILCALL) != 0)
return 0;
if (btrace_find_call_by_number (&it, &tp->btrace, callee->up) == 0)
return 0;
bfun = btrace_call_get (&it);
}
if (bfun == NULL)
@ -1713,7 +1721,9 @@ record_btrace_tailcall_frame_sniffer (const struct frame_unwind *self,
{
const struct btrace_function *bfun, *callee;
struct btrace_frame_cache *cache;
struct btrace_call_iterator it;
struct frame_info *next;
struct thread_info *tinfo;
next = get_next_frame (this_frame);
if (next == NULL)
@ -1726,16 +1736,18 @@ record_btrace_tailcall_frame_sniffer (const struct frame_unwind *self,
if ((callee->flags & BFUN_UP_LINKS_TO_TAILCALL) == 0)
return 0;
bfun = callee->up;
if (bfun == NULL)
tinfo = find_thread_ptid (inferior_ptid);
if (btrace_find_call_by_number (&it, &tinfo->btrace, callee->up) == 0)
return 0;
bfun = btrace_call_get (&it);
DEBUG ("[frame] sniffed tailcall frame for %s on level %d",
btrace_get_bfun_name (bfun), bfun->level);
/* This is our frame. Initialize the frame cache. */
cache = bfcache_new (this_frame);
cache->tp = find_thread_ptid (inferior_ptid);
cache->tp = tinfo;
cache->bfun = bfun;
*this_cache = cache;