gdb: add printer for selfhosted Type

src/type.zig

@@ -5092,6 +5092,7 @@ pub const Type = extern union {
         pub const no_payload_count = @enumToInt(last_no_payload_tag) + 1;
 
         pub fn Type(comptime t: Tag) type {
+            // Keep in sync with tools/zig-gdb.py
             return switch (t) {
                 .u1,
                 .u8,

tools/zig-gdb.py

@@ -1,8 +1,9 @@
 # pretty printing for stage1, stage2 and the standard library
 # put "source /path/to/zig-gdb.py" in ~/.gdbinit to load it automatically
 
-import gdb.printing
 import re
+import gdb.printing
+import gdb.types
 
 class ZigListPrinter:
     def __init__(self, val):
@@ -184,6 +185,95 @@ class ArrayHashMapPrinter:
                 return 'map'
         return 'array'
 
+class TypePrinter:
+    no_payload_count = 4096
+
+    # Keep in sync with src/type.zig
+    # Types which have no payload do not need to be entered here.
+    payload_type_names = {
+        'array_u8': 'type.Len',
+        'array_u8_sentinel_0': 'Len',
+
+        'single_const_pointer': 'ElemType',
+        'single_mut_pointer': 'ElemType',
+        'many_const_pointer': 'ElemType',
+        'many_mut_pointer': 'ElemType',
+        'c_const_pointer': 'ElemType',
+        'c_mut_pointer': 'ElemType',
+        'const_slice': 'ElemType',
+        'mut_slice': 'ElemType',
+        'optional': 'ElemType',
+        'optional_single_mut_pointer': 'ElemType',
+        'optional_single_const_pointer': 'ElemType',
+        'anyframe_T': 'ElemType',
+
+        'int_signed': 'Bits',
+        'int_unsigned': 'Bits',
+
+        'error_set': 'ErrorSet',
+        'error_set_inferred': 'ErrorSetInferred',
+        'error_set_merged': 'ErrorSetMerged',
+
+        'array': 'Array',
+        'vector': 'Array',
+
+        'array_sentinel': 'ArraySentinel',
+        'pointer': 'Pointer',
+        'function': 'Function',
+        'error_union': 'ErrorUnion',
+        'error_set_single': 'Name',
+        'opaque': 'Opaque',
+        'struct': 'Struct',
+        'union': 'Union',
+        'union_tagged': 'Union',
+        'enum_full, .enum_nonexhaustive': 'EnumFull',
+        'enum_simple': 'EnumSimple',
+        'enum_numbered': 'EnumNumbered',
+        'empty_struct': 'ContainerScope',
+        'tuple': 'Tuple',
+        'anon_struct': 'AnonStruct',
+    }
+
+    def __init__(self, val):
+        self.val = val
+
+    def tag(self):
+        tag_if_small_enough = self.val['tag_if_small_enough']
+        tag_type = tag_if_small_enough.type
+
+        if tag_if_small_enough < TypePrinter.no_payload_count:
+            return tag_if_small_enough
+        else:
+            return self.val['ptr_otherwise'].dereference()['tag']
+
+    def payload_type(self):
+        tag = self.tag()
+        if tag is None:
+            return None
+
+        type_name = TypePrinter.payload_type_names.get(str(tag))
+        if type_name is None:
+            return None
+        return gdb.lookup_type('struct type.%s' % type_name)
+
+    def to_string(self):
+        tag = self.tag()
+        if tag is None:
+            return 'Type.(invalid type)'
+        if self.val['tag_if_small_enough'] < TypePrinter.no_payload_count:
+            return '.%s' % str(tag)
+        return None
+
+    def children(self):
+        if self.val['tag_if_small_enough'] < TypePrinter.no_payload_count:
+            return
+
+        yield ('tag', '.%s' % str(self.tag()))
+
+        payload_type = self.payload_type()
+        if payload_type is not None:
+            yield ('payload', self.val['ptr_otherwise'].cast(payload_type.pointer()).dereference()['data'])
+
 pp1 = gdb.printing.RegexpCollectionPrettyPrinter('Zig stage1 compiler')
 pp1.add_printer('Buf', '^Buf$', BufPrinter)
 pp1.add_printer('ZigList<char>', '^ZigList<char>$', BufPrinter)
@@ -193,6 +283,7 @@ gdb.printing.register_pretty_printer(gdb.current_objfile(), pp1)
 pplang = gdb.printing.RegexpCollectionPrettyPrinter('Zig language')
 pplang.add_printer('Slice', '^\[\]u8', SliceStringPrinter)
 pplang.add_printer('Slice', '^\[\]', SlicePrinter)
+gdb.printing.register_pretty_printer(gdb.current_objfile(), pplang)
 
 ppstd = gdb.printing.RegexpCollectionPrettyPrinter('Zig standard library')
 ppstd.add_printer('ArrayList', r'^std\.array_list\.ArrayListAligned(Unmanaged)?\(.*\)$', ArrayListPrinter)
@@ -200,3 +291,8 @@ ppstd.add_printer('MultiArrayList', r'^std\.multi_array_list\.MultiArrayList\(.*
 ppstd.add_printer('HashMap', r'^std\.hash_map\.HashMap(Unmanaged)?\(.*\)$', HashMapPrinter)
 ppstd.add_printer('ArrayHashMap', r'^std\.array_hash_map\.ArrayHashMap(Unmanaged)?\(.*\)$', ArrayHashMapPrinter)
 gdb.printing.register_pretty_printer(gdb.current_objfile(), ppstd)
+
+pp2 = gdb.printing.RegexpCollectionPrettyPrinter('Zig stage2 compiler')
+ppstd.add_printer('Type', r'^type\.Type$', TypePrinter)
+gdb.printing.register_pretty_printer(gdb.current_objfile(), pp2)
+