tint: add pretty printers for gdb and lldb
Currently supports pretty printing of:
- tint::Utils::Vector, VectorRef, and Slice
- tint::Utils::Hashset, Hashmap
Change-Id: Ifbf2547b0f87d7fde8d9ff0dd458aa35c5fd57f4
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/106720
Reviewed-by: dan sinclair <dsinclair@google.com>
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
diff --git a/src/tint/tint_lldb.py b/src/tint/tint_lldb.py
new file mode 100644
index 0000000..85a93ff
--- /dev/null
+++ b/src/tint/tint_lldb.py
@@ -0,0 +1,397 @@
+# Copyright 2022 The Tint Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Pretty printers for the Tint project.
+#
+# If using lldb from command line, add a line to your ~/.lldbinit to import the printers:
+#
+# command script import /path/to/dawn/src/tint/tint_lldb.py
+#
+#
+# If using VS Code on MacOS with the Microsoft C/C++ extension, add the following to
+# your launch.json (make sure you specify an absolute path to tint_lldb.py):
+#
+# "name": "Launch",
+# "type": "cppdbg",
+# "request": "launch",
+# ...
+# "setupCommands": [
+# {
+# "description": "Load tint pretty printers",
+# "ignoreFailures": false,
+# "text": "command script import /path/to/dawn/src/tint/tint_lldb.py,
+# }
+# ]
+#
+# If using VS Code with the CodeLLDB extension (https://github.com/vadimcn/vscode-lldb),
+# add the following to your launch.json:
+#
+# "name": "Launch",
+# "type": "lldb",
+# "request": "launch",
+# ...
+# "initCommands": [
+# "command script import /path/to/dawn/src/tint/tint_lldb.py"
+# ]
+
+# Based on pretty printers for:
+# Rust: https://github.com/vadimcn/vscode-lldb/blob/master/formatters/rust.py
+# Dlang: https://github.com/Pure-D/dlang-debug/blob/master/lldb_dlang.py
+#
+#
+# Tips for debugging using VS Code:
+#
+# - Set a breakpoint where you can view the types you want to debug/write pretty printers for.
+# - Debug Console: -exec command script import /path/to/dawn/src/tint/tint_lldb.py
+# - You can re-run the above command to reload the printers after modifying the python script.
+
+# - Useful docs:
+# Formattesr: https://lldb.llvm.org/use/variable.html
+# Python API: https://lldb.llvm.org/python_api.html
+# Especially:
+# SBType: https://lldb.llvm.org/python_api/lldb.SBType.html
+# SBValue: https://lldb.llvm.org/python_api/lldb.SBValue.html
+
+from __future__ import print_function, division
+import sys
+import logging
+import re
+import lldb
+import types
+
+if sys.version_info[0] == 2:
+ # python2-based LLDB accepts utf8-encoded ascii strings only.
+ def to_lldb_str(s): return s.encode(
+ 'utf8', 'backslashreplace') if isinstance(s, unicode) else s
+ range = xrange
+else:
+ to_lldb_str = str
+
+string_encoding = "escape" # remove | unicode | escape
+
+log = logging.getLogger(__name__)
+
+module = sys.modules[__name__]
+tint_category = None
+
+
+def __lldb_init_module(debugger, dict):
+ global tint_category
+
+ tint_category = debugger.CreateCategory('tint')
+ tint_category.SetEnabled(True)
+
+ attach_synthetic_to_type(
+ UtilsSlicePrinter, r'^tint::utils::Slice<.+>$', True)
+
+ attach_synthetic_to_type(
+ UtilsVectorPrinter, r'^tint::utils::Vector<.+>$', True)
+
+ attach_synthetic_to_type(
+ UtilsVectorRefPrinter, r'^tint::utils::VectorRef<.+>$', True)
+
+ attach_synthetic_to_type(
+ UtilsHashsetPrinter, r'^tint::utils::Hashset<.+>$', True)
+
+ attach_synthetic_to_type(
+ UtilsHashmapPrinter, r'^tint::utils::Hashmap<.+>$', True)
+
+
+def attach_synthetic_to_type(synth_class, type_name, is_regex=False):
+ global module, tint_category
+ synth = lldb.SBTypeSynthetic.CreateWithClassName(
+ __name__ + '.' + synth_class.__name__)
+ synth.SetOptions(lldb.eTypeOptionCascade)
+ ret = tint_category.AddTypeSynthetic(
+ lldb.SBTypeNameSpecifier(type_name, is_regex), synth)
+ log.debug('attaching synthetic %s to "%s", is_regex=%s -> %s',
+ synth_class.__name__, type_name, is_regex, ret)
+
+ def summary_fn(valobj, dict): return get_synth_summary(
+ synth_class, valobj, dict)
+ # LLDB accesses summary fn's by name, so we need to create a unique one.
+ summary_fn.__name__ = '_get_synth_summary_' + synth_class.__name__
+ setattr(module, summary_fn.__name__, summary_fn)
+ attach_summary_to_type(summary_fn, type_name, is_regex)
+
+
+def attach_summary_to_type(summary_fn, type_name, is_regex=False):
+ global module, tint_category
+ summary = lldb.SBTypeSummary.CreateWithFunctionName(
+ __name__ + '.' + summary_fn.__name__)
+ summary.SetOptions(lldb.eTypeOptionCascade)
+ ret = tint_category.AddTypeSummary(
+ lldb.SBTypeNameSpecifier(type_name, is_regex), summary)
+ log.debug('attaching summary %s to "%s", is_regex=%s -> %s',
+ summary_fn.__name__, type_name, is_regex, ret)
+
+
+def get_synth_summary(synth_class, valobj, dict):
+ ''''
+ get_summary' is annoyingly not a part of the standard LLDB synth provider API.
+ This trick allows us to share data extraction logic between synth providers and their sibling summary providers.
+ '''
+ synth = synth_class(valobj.GetNonSyntheticValue(), dict)
+ synth.update()
+ summary = synth.get_summary()
+ return to_lldb_str(summary)
+
+
+def member(valobj, *chain):
+ '''Performs chained GetChildMemberWithName lookups'''
+ for name in chain:
+ valobj = valobj.GetChildMemberWithName(name)
+ return valobj
+
+
+class Printer(object):
+ '''Base class for Printers'''
+
+ def __init__(self, valobj, dict={}):
+ self.valobj = valobj
+ self.initialize()
+
+ def initialize(self):
+ return None
+
+ def update(self):
+ return False
+
+ def num_children(self):
+ return 0
+
+ def has_children(self):
+ return False
+
+ def get_child_at_index(self, index):
+ return None
+
+ def get_child_index(self, name):
+ return None
+
+ def get_summary(self):
+ return None
+
+ def member(self, *chain):
+ '''Performs chained GetChildMemberWithName lookups'''
+ return member(self.valobj, *chain)
+
+ def template_params(self):
+ '''Returns list of template params values (as strings)'''
+ type_name = self.valobj.GetTypeName()
+ params = []
+ level = 0
+ start = 0
+ for i, c in enumerate(type_name):
+ if c == '<':
+ level += 1
+ if level == 1:
+ start = i + 1
+ elif c == '>':
+ level -= 1
+ if level == 0:
+ params.append(type_name[start:i].strip())
+ elif c == ',' and level == 1:
+ params.append(type_name[start:i].strip())
+ start = i + 1
+ return params
+
+ def template_param_at(self, index):
+ '''Returns template param value at index (as string)'''
+ return self.template_params()[index]
+
+
+class UtilsSlicePrinter(Printer):
+ '''Printer for tint::utils::Slice<T>'''
+
+ def initialize(self):
+ self.len = self.valobj.GetChildMemberWithName('len')
+ self.cap = self.valobj.GetChildMemberWithName('cap')
+ self.data = self.valobj.GetChildMemberWithName('data')
+ self.elem_type = self.data.GetType().GetPointeeType()
+ self.elem_size = self.elem_type.GetByteSize()
+
+ def get_summary(self):
+ return 'length={} capacity={}'.format(self.len.GetValueAsUnsigned(), self.cap.GetValueAsUnsigned())
+
+ def num_children(self):
+ # NOTE: VS Code on MacOS hangs if we try to expand something too large, so put an artificial limit
+ # until we can figure out how to know if this is a valid instance.
+ return min(self.len.GetValueAsUnsigned(), 256)
+
+ def has_children(self):
+ return True
+
+ def get_child_at_index(self, index):
+ try:
+ if not 0 <= index < self.num_children():
+ return None
+ # TODO: return self.value_at(index)
+ offset = index * self.elem_size
+ return self.data.CreateChildAtOffset('[%s]' % index, offset, self.elem_type)
+ except Exception as e:
+ log.error('%s', e)
+ raise
+
+ def value_at(self, index):
+ '''Returns array value at index'''
+ offset = index * self.elem_size
+ return self.data.CreateChildAtOffset('[%s]' % index, offset, self.elem_type)
+
+
+class UtilsVectorPrinter(Printer):
+ '''Printer for tint::utils::Vector<T, N>'''
+
+ def initialize(self):
+ self.slice = self.member('impl_', 'slice')
+ self.slice_printer = UtilsSlicePrinter(self.slice)
+ self.fixed_size = int(self.template_param_at(1))
+ self.cap = self.slice_printer.member('cap')
+
+ def get_summary(self):
+ using_heap = self.cap.GetValueAsUnsigned() > self.fixed_size
+ return 'heap={} {}'.format(using_heap, self.slice_printer.get_summary())
+
+ def num_children(self):
+ return self.slice_printer.num_children()
+
+ def has_children(self):
+ return self.slice_printer.has_children()
+
+ def get_child_at_index(self, index):
+ return self.slice_printer.get_child_at_index(index)
+
+ def make_slice_printer(self):
+ return UtilsSlicePrinter(self.slice)
+
+
+class UtilsVectorRefPrinter(Printer):
+ '''Printer for tint::utils::VectorRef<T>'''
+
+ def initialize(self):
+ self.slice = self.member('slice_')
+ self.slice_printer = UtilsSlicePrinter(self.slice)
+ self.can_move = self.member('can_move_')
+
+ def get_summary(self):
+ return 'can_move={} {}'.format(self.can_move.GetValue(), self.slice_printer.get_summary())
+
+ def num_children(self):
+ return self.slice_printer.num_children()
+
+ def has_children(self):
+ return self.slice_printer.has_children()
+
+ def get_child_at_index(self, index):
+ return self.slice_printer.get_child_at_index(index)
+
+
+class UtilsHashsetPrinter(Printer):
+ '''Printer for Hashset<T, N, HASH, EQUAL>'''
+
+ def initialize(self):
+ self.slice = UtilsVectorPrinter(
+ self.member('slots_')).make_slice_printer()
+
+ self.try_read_std_optional_func = self.try_read_std_optional
+
+ def update(self):
+ self.valid_slots = []
+ for slot in range(0, self.slice.num_children()):
+ v = self.slice.value_at(slot)
+ if member(v, 'hash').GetValueAsUnsigned() != 0:
+ self.valid_slots.append(slot)
+ return False
+
+ def get_summary(self):
+ return 'length={}'.format(self.num_children())
+
+ def num_children(self):
+ return len(self.valid_slots)
+
+ def has_children(self):
+ return True
+
+ def get_child_at_index(self, index):
+ slot = self.valid_slots[index]
+ v = self.slice.value_at(slot)
+ value = member(v, 'value')
+
+ # value is a std::optional, let's try to extract its value for display
+ kvp = self.try_read_std_optional_func(slot, value)
+ if kvp is None:
+ # If we failed, just output the slot and value as is, which will use
+ # the default printer for std::optional.
+ kvp = slot, value
+
+ return kvp[1].CreateChildAtOffset('[{}]'.format(kvp[0]), 0, kvp[1].GetType())
+
+ def try_read_std_optional(self, slot, value):
+ try:
+ # libc++
+ v = value.EvaluateExpression('__val_')
+ if v.name is not None:
+ return slot, v
+
+ # libstdc++
+ v = value.EvaluateExpression('_M_payload._M_payload._M_value')
+ if v.name is not None:
+ return slot, v
+ return None
+ except:
+ return None
+
+
+class UtilsHashmapPrinter(Printer):
+ '''Printer for Hashmap<K, V, N, HASH, EQUAL>'''
+
+ def initialize(self):
+ self.hash_set = UtilsHashsetPrinter(self.member('set_'))
+ # Replace the lookup function so we can extract the key and value out of the std::optionals in the Hashset
+ self.hash_set.try_read_std_optional_func = self.try_read_std_optional
+
+ def update(self):
+ self.hash_set.update()
+
+ def get_summary(self):
+ return self.hash_set.get_summary()
+
+ def num_children(self):
+ return self.hash_set.num_children()
+
+ def has_children(self):
+ return self.hash_set.has_children()
+
+ def get_child_at_index(self, index):
+ return self.hash_set.get_child_at_index(index)
+
+ def try_read_std_optional(self, slot, value):
+ try:
+ # libc++
+ val = value.EvaluateExpression('__val_')
+ k = val.EvaluateExpression('key')
+ v = val.EvaluateExpression('value')
+ if k.name is not None and v.name is not None:
+ return k.GetValue(), v
+
+ # libstdc++
+ val = value.EvaluateExpression('_M_payload._M_payload._M_value')
+ k = val.EvaluateExpression('key')
+ v = val.EvaluateExpression('value')
+ if k.name is not None and v.name is not None:
+ return k.GetValue(), v
+ except:
+ pass
+ # Failed, fall back on hash_set
+ return self.hash_set.try_read_std_optional(slot, value)
