Add gdb pretty-printers for simple types (#11499)

This adds `gdb` pretty printers for `rmm::device_uvector`, `thrust::*_vector`, `thrust::device_reference` and `cudf::*_span`. The implementation is based on NVIDIA/thrust#1631. I will probably backport the thrust-specific changes to there as well, but since the location of the thrust source is not fixed, I'd prefer having all types in a self-contained file.

Authors:
  - Tobias Ribizel (https://github.com/upsj)

Approvers:
  - Bradley Dice (https://github.com/bdice)
  - Karthikeyan (https://github.com/karthikeyann)

URL: #11499

cpp/CMakeLists.txt

@@ -749,6 +749,11 @@ if(CUDF_BUILD_BENCHMARKS)
   add_subdirectory(benchmarks)
 endif()
 
+# build pretty-printer load script
+if(Thrust_SOURCE_DIR AND rmm_SOURCE_DIR)
+  configure_file(scripts/load-pretty-printers.in load-pretty-printers @ONLY)
+endif()
+
 # ##################################################################################################
 # * install targets -------------------------------------------------------------------------------
 rapids_cmake_install_lib_dir(lib_dir)

cpp/scripts/gdb-pretty-printers.py

@@ -0,0 +1,84 @@
+# Copyright (c) 2022, NVIDIA CORPORATION.
+#
+# 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.
+#
+
+import gdb
+
+global_locals = locals()
+if not all(
+    name in global_locals
+    for name in (
+        "HostIterator",
+        "DeviceIterator",
+        "is_template_type_not_alias",
+        "template_match",
+    )
+):
+    raise NameError(
+        "This file expects the RMM pretty-printers to be loaded already. "
+        "Either load them manually, or use the generated load-pretty-printers "
+        "script in the build directory"
+    )
+
+
+class CudfHostSpanPrinter(gdb.printing.PrettyPrinter):
+    """Print a cudf::host_span"""
+
+    def __init__(self, val):
+        self.val = val
+        self.pointer = val["_data"]
+        self.size = int(val["_size"])
+
+    def children(self):
+        return HostIterator(self.pointer, self.size)
+
+    def to_string(self):
+        return f"{self.val.type} of length {self.size} at {hex(self.pointer)}"
+
+    def display_hint(self):
+        return "array"
+
+
+class CudfDeviceSpanPrinter(gdb.printing.PrettyPrinter):
+    """Print a cudf::device_span"""
+
+    def __init__(self, val):
+        self.val = val
+        self.pointer = val["_data"]
+        self.size = int(val["_size"])
+
+    def children(self):
+        return DeviceIterator(self.pointer, self.size)
+
+    def to_string(self):
+        return f"{self.val.type} of length {self.size} at {hex(self.pointer)}"
+
+    def display_hint(self):
+        return "array"
+
+
+def lookup_cudf_type(val):
+    if not str(val.type.unqualified()).startswith("cudf::"):
+        return None
+    suffix = str(val.type.unqualified())[6:]
+    if not is_template_type_not_alias(suffix):
+        return None
+    if template_match(suffix, "host_span"):
+        return CudfHostSpanPrinter(val)
+    if template_match(suffix, "device_span"):
+        return CudfDeviceSpanPrinter(val)
+    return None
+
+
+gdb.pretty_printers.append(lookup_cudf_type)

cpp/scripts/load-pretty-printers.in

@@ -0,0 +1,3 @@
+source @Thrust_SOURCE_DIR@/scripts/gdb-pretty-printers.py
+source @rmm_SOURCE_DIR@/scripts/gdb-pretty-printers.py
+source @PROJECT_SOURCE_DIR@/scripts/gdb-pretty-printers.py