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Handle StackFrameFormat in DAP

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DAP specifies a StackFrameFormat object that can be used to change how
the "name" part of a stack frame is constructed.  While this output
can already be done in a nicer way (and also letting the client choose
the formatting), nevertheless it is in the spec, so I figured I'd
implement it.

While implementing this, I discovered that the current code does not
correctly preserve frame IDs across requests.  I rewrote frame
iteration to preserve this, and it turned out to be simpler to combine
these patches.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30475
This commit is contained in:
Tom Tromey
2023-10-06 13:40:39 -06:00
parent 74affa1bc0
commit 1920148904
6 changed files with 453 additions and 47 deletions
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110
gdb/python/lib/gdb/dap/bt.py
View File

@@ -16,37 +16,68 @@
import gdb
import os
from gdb.frames import frame_iterator
from .frames import frame_id
# This is deprecated in 3.9, but required in older versions.
from typing import Optional
from .frames import dap_frame_generator
from .modules import module_id
from .scopes import symbol_value
from .server import request, capability
from .sources import make_source
from .startup import send_gdb_with_response, in_gdb_thread
from .state import set_thread
from .typecheck import type_check
from .varref import apply_format
# Helper function to compute parameter information for a stack frame.
@in_gdb_thread
def _compute_parameters(frame, stack_format):
arg_iter = frame.frame_args()
if arg_iter is None:
return ""
result = []
for arg in arg_iter:
desc = []
name, val = symbol_value(arg, frame)
# We don't try to use any particular language's syntax for the
# output here.
if stack_format["parameterTypes"]:
desc.append("[" + str(val.type) + "]")
if stack_format["parameterNames"]:
desc.append(name)
# If both the name and the value are requested, insert an
# '=' for clarity.
if stack_format["parameterValues"]:
desc.append("=")
if stack_format["parameterValues"]:
desc.append(val.format_string(summary=True))
result.append(" ".join(desc))
return ", ".join(result)
# Helper function to compute a stack trace.
@in_gdb_thread
def _backtrace(thread_id, levels, startFrame, value_format):
with apply_format(value_format):
def _backtrace(thread_id, levels, startFrame, stack_format):
with apply_format(stack_format):
set_thread(thread_id)
frames = []
if levels == 0:
# Zero means all remaining frames.
high = -1
else:
# frame_iterator uses an inclusive range, so subtract one.
high = startFrame + levels - 1
try:
frame_iter = frame_iterator(gdb.newest_frame(), startFrame, high)
except gdb.error:
frame_iter = ()
for current_frame in frame_iter:
frame_iter = dap_frame_generator(startFrame, levels, stack_format["includeAll"])
for frame_id, current_frame in frame_iter:
pc = current_frame.address()
# The stack frame format affects the name, so we build it up
# piecemeal and assign it at the end.
name = current_frame.function()
# The meaning of StackFrameFormat.parameters was clarified
# in https://github.com/microsoft/debug-adapter-protocol/issues/411.
if stack_format["parameters"] and (
stack_format["parameterTypes"]
or stack_format["parameterNames"]
or stack_format["parameterValues"]
):
name += "(" + _compute_parameters(current_frame, stack_format) + ")"
newframe = {
"id": frame_id(current_frame),
"name": current_frame.function(),
"id": frame_id,
# This must always be supplied, but we will set it
# correctly later if that is possible.
"line": 0,
@@ -54,15 +85,20 @@ def _backtrace(thread_id, levels, startFrame, value_format):
"column": 0,
"instructionPointerReference": hex(pc),
}
objfile = gdb.current_progspace().objfile_for_address(pc)
if objfile is not None:
newframe["moduleId"] = module_id(objfile)
line = current_frame.line()
if line is not None:
newframe["line"] = line
if stack_format["line"]:
name += ", line " + str(line)
objfile = gdb.current_progspace().objfile_for_address(pc)
if objfile is not None:
newframe["moduleId"] = module_id(objfile)
if stack_format["module"]:
name += ", module " + objfile.username
filename = current_frame.filename()
if filename is not None:
newframe["source"] = make_source(filename, os.path.basename(filename))
newframe["name"] = name
frames.append(newframe)
# Note that we do not calculate totalFrames here. Its absence
# tells the client that it may simply ask for frames until a
@@ -72,11 +108,45 @@ def _backtrace(thread_id, levels, startFrame, value_format):
}
# A helper function that checks the types of the elements of a
# StackFrameFormat, and converts this to a dict where all the members
# are set. This simplifies the implementation code a bit.
@type_check
def check_stack_frame(
*,
# Note that StackFrameFormat extends ValueFormat, which is why
# "hex" appears here.
hex: Optional[bool] = False,
parameters: Optional[bool] = False,
parameterTypes: Optional[bool] = False,
parameterNames: Optional[bool] = False,
parameterValues: Optional[bool] = False,
line: Optional[bool] = False,
module: Optional[bool] = False,
includeAll: Optional[bool] = False,
**rest
):
return {
"hex": hex,
"parameters": parameters,
"parameterTypes": parameterTypes,
"parameterNames": parameterNames,
"parameterValues": parameterValues,
"line": line,
"module": module,
"includeAll": includeAll,
}
@request("stackTrace")
@capability("supportsDelayedStackTraceLoading")
def stacktrace(
*, levels: int = 0, startFrame: int = 0, threadId: int, format=None, **extra
):
# It's simpler if the format is always set.
if format is None:
format = {}
format = check_stack_frame(**format)
return send_gdb_with_response(
lambda: _backtrace(threadId, levels, startFrame, format)
)

113
gdb/python/lib/gdb/dap/frames.py
View File

@@ -14,6 +14,9 @@
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import gdb
import itertools
from gdb.frames import frame_iterator
from .startup import in_gdb_thread
@@ -24,29 +27,23 @@ from .startup import in_gdb_thread
_all_frames = []
# Map from a global thread ID to a memoizing frame iterator.
_iter_map = {}
# Clear all the frame IDs.
@in_gdb_thread
def _clear_frame_ids(evt):
global _all_frames
_all_frames = []
global _iter_map
_iter_map = {}
# Clear the frame ID map whenever the inferior runs.
gdb.events.cont.connect(_clear_frame_ids)
@in_gdb_thread
def frame_id(frame):
"""Return the frame identifier for FRAME."""
global _all_frames
for i in range(0, len(_all_frames)):
if _all_frames[i] == frame:
return i
result = len(_all_frames)
_all_frames.append(frame)
return result
@in_gdb_thread
def frame_for_id(id):
"""Given a frame identifier ID, return the corresponding frame."""
@@ -59,3 +56,95 @@ def select_frame(id):
"""Given a frame identifier ID, select the corresponding frame."""
frame = frame_for_id(id)
frame.inferior_frame().select()
# A simple memoizing iterator. Note that this is not very robust.
# For example, you can't start two copies of the iterator and then
# alternate fetching items from each. Instead, it implements just
# what is needed for the current callers.
class _MemoizingIterator:
def __init__(self, iterator):
self.iterator = iterator
self.seen = []
def __iter__(self):
# First the memoized items.
for item in self.seen:
yield item
# Now memoize new items.
for item in self.iterator:
self.seen.append(item)
yield item
# A generator that fetches frames and pairs them with a frame ID. It
# yields tuples of the form (ID, ELIDED, FRAME), where ID is the
# generated ID, ELIDED is a boolean indicating if the frame should be
# elided, and FRAME is the frame itself. This approach lets us
# memoize the result and assign consistent IDs, independent of how
# "includeAll" is set in the request.
@in_gdb_thread
def _frame_id_generator():
try:
base_iterator = frame_iterator(gdb.newest_frame(), 0, -1)
except gdb.error:
base_iterator = ()
# Helper function to assign an ID to a frame.
def get_id(frame):
global _all_frames
num = len(_all_frames)
_all_frames.append(frame)
return num
def yield_frames(iterator, for_elided):
for frame in iterator:
# Unfortunately the frame filter docs don't describe
# whether the elided frames conceptually come before or
# after the eliding frame. Here we choose after.
yield (get_id(frame), for_elided, frame)
elided = frame.elided()
if elided is not None:
yield from yield_frames(frame.elided(), True)
yield from yield_frames(base_iterator, False)
# Return the memoizing frame iterator for the selected thread.
@in_gdb_thread
def _get_frame_iterator():
thread_id = gdb.selected_thread().global_num
global _iter_map
if thread_id not in _iter_map:
_iter_map[thread_id] = _MemoizingIterator(_frame_id_generator())
return _iter_map[thread_id]
# A helper function that creates an iterable that returns (ID, FRAME)
# pairs. It uses the memoizing frame iterator, but also handles the
# "includeAll" member of StackFrameFormat.
@in_gdb_thread
def dap_frame_generator(frame_low, levels, include_all):
"""A generator that yields identifiers and frames.
Each element is a pair of the form (ID, FRAME).
ID is the internally-assigned frame ID.
FRAME is a FrameDecorator of some kind.
Arguments are as to the stackTrace request."""
base_iterator = _get_frame_iterator()
if not include_all:
base_iterator = itertools.filterfalse(lambda item: item[1], base_iterator)
if levels == 0:
# Zero means all remaining frames.
frame_high = None
else:
frame_high = frame_low + levels
base_iterator = itertools.islice(base_iterator, frame_low, frame_high)
for ident, _, frame in base_iterator:
yield (ident, frame)

39
gdb/python/lib/gdb/dap/scopes.py
View File

@@ -36,6 +36,29 @@ def clear_scopes(event):
gdb.events.cont.connect(clear_scopes)
# A helper function to compute the value of a symbol. SYM is either a
# gdb.Symbol, or an object implementing the SymValueWrapper interface.
# FRAME is a frame wrapper, as produced by a frame filter. Returns a
# tuple of the form (NAME, VALUE), where NAME is the symbol's name and
# VALUE is a gdb.Value.
@in_gdb_thread
def symbol_value(sym, frame):
inf_frame = frame.inferior_frame()
# Make sure to select the frame first. Ideally this would not
# be needed, but this is a way to set the current language
# properly so that language-dependent APIs will work.
inf_frame.select()
name = str(sym.symbol())
val = sym.value()
if val is None:
# No synthetic value, so must read the symbol value
# ourselves.
val = sym.symbol().value(inf_frame)
elif not isinstance(val, gdb.Value):
val = gdb.Value(val)
return (name, val)
class _ScopeReference(BaseReference):
def __init__(self, name, hint, frame, var_list):
super().__init__(name)
@@ -67,21 +90,7 @@ class _ScopeReference(BaseReference):
@in_gdb_thread
def fetch_one_child(self, idx):
# Make sure to select the frame first. Ideally this would not
# be needed, but this is a way to set the current language
# properly so that language-dependent APIs will work.
self.inf_frame.select()
# Here SYM will conform to the SymValueWrapper interface.
sym = self.var_list[idx]
name = str(sym.symbol())
val = sym.value()
if val is None:
# No synthetic value, so must read the symbol value
# ourselves.
val = sym.symbol().value(self.inf_frame)
elif not isinstance(val, gdb.Value):
val = gdb.Value(val)
return (name, val)
return symbol_value(self.var_list[idx], self.frame)
class _RegisterReference(_ScopeReference):