Add gdb printer

Author: mborland

extra/int128_printer_gdb.py

@@ -0,0 +1,116 @@
+# Copyright 2025 Matt Borland
+# Distributed under the Boost Software License, Version 1.0.
+# https://www.boost.org/LICENSE_1_0.txt
+#
+# Struct definitions:
+# struct uint128_t { std::uint64_t low; std::uint64_t high; };
+# struct int128_t { std::uint64_t low; std::int64_t high; };
+#
+# On big endian machines the word order is reversed
+#
+# Usage: source int128_printer.py
+
+import gdb
+import gdb.printing
+import re
+
+class Uint128Printer:
+ """Pretty printer for uint128_t type"""
+
+ def __init__(self, val):
+ self.val = val
+
+ def to_string(self):
+ try:
+ high = int(self.val["high"]) & 0xFFFFFFFFFFFFFFFF # Treat as unsigned
+ low = int(self.val["low"]) & 0xFFFFFFFFFFFFFFFF
+
+ value = (high << 64) | low
+ return f"{value:,}"
+ except Exception as e:
+ return f"<invalid uint128_t: {e}>"
+
+ def children(self):
+ yield "low", self.val["low"]
+ yield "high", self.val["high"]
+
+ def display_hint(self):
+ return None
+
+
+class Int128Printer:
+ """Pretty printer for int128_t type"""
+
+ def __init__(self, val):
+ self.val = val
+
+ def to_string(self):
+ try:
+ # high is std::int64_t (signed)
+ high = int(self.val["high"])
+ # Ensure high is treated as signed 64-bit
+ if high >= 0x8000000000000000:
+ high -= 0x10000000000000000
+
+ # low is std::uint64_t (unsigned)
+ low = int(self.val["low"]) & 0xFFFFFFFFFFFFFFFF
+
+ value = (high << 64) + low
+ return f"{value:,}"
+ except Exception as e:
+ return f"<invalid int128_t: {e}>"
+
+ def children(self):
+ yield "low", self.val["low"]
+ yield "high", self.val["high"]
+
+ def display_hint(self):
+ return None
+
+
+def lookup_int128_type(val):
+ """
+ Lookup function to detect if a type should use our pretty printers.
+ Returns the appropriate printer or None.
+ """
+ # Get the basic type name, stripping references and const qualifiers
+ type_obj = val.type
+
+ # Handle references and pointers
+ if type_obj.code == gdb.TYPE_CODE_REF:
+ type_obj = type_obj.target()
+ if type_obj.code == gdb.TYPE_CODE_PTR:
+ return None # Don't handle pointers directly
+
+ # Strip const/volatile qualifiers
+ type_obj = type_obj.unqualified()
+
+ type_name = str(type_obj)
+
+ # Patterns to match uint128_t and int128_t types
+ uint128_pattern = re.compile(
+ r"^(boost::int128::uint128_t|(\w+::)*uint128_t|uint128_t)$"
+ )
+ int128_pattern = re.compile(
+ r"^(boost::int128::int128_t|(\w+::)*int128_t|int128_t)$"
+ )
+
+ if uint128_pattern.match(type_name):
+ return Uint128Printer(val)
+ if int128_pattern.match(type_name):
+ return Int128Printer(val)
+
+ return None
+
+
+def register_int128_printers(objfile=None):
+ """Register the int128 pretty printers."""
+ if objfile is None:
+ objfile = gdb
+
+ objfile.pretty_printers.append(lookup_int128_type)
+
+
+# Auto-register when the script is sourced
+register_int128_printers()
+print("int128_t and uint128_t pretty printers loaded successfully")