Modified: trunk/Tools/ChangeLog (233660 => 233661)
--- trunk/Tools/ChangeLog 2018-07-09 22:30:40 UTC (rev 233660)
+++ trunk/Tools/ChangeLog 2018-07-09 23:07:26 UTC (rev 233661)
@@ -1,3 +1,38 @@
+2018-07-09 Simon Fraser <[email protected]>
+
+ Fix dump-class-layout to show bit padding, and fix issues with padding offsets
+ https://bugs.webkit.org/show_bug.cgi?id=187442
+
+ Reviewed by Daniel Bates.
+
+ Synthetic padding members were shown with the wrong offset because they used the
+ absolute offset rather than the class-relative offset. This didn't change the padding
+ math, but made the output confusing.
+
+ Also add support for showing empty bits in bitfields, and fix computation of padding
+ after bitfields. Empty bits are computed by inserting a bit padding member after
+ a bitfield that is not followed by another bitfield (making the assumption that bit
+ padding will fill to the next byte boundary).
+
+ The computation of padding after bitfields was also wrong, since lldb's member_type.GetByteSize()
+ just reports the size of the type without the bitfield modifier (e.g. for "unsigned : 2" it returned 4).
+ Fix by setting the byte size for bitfield fields to the number of bits rounded up to the next byte;
+ this allows byte padding following the bitfield to be computed correctly.
+
+ Add or modify test to cover these issues.
+
+ * lldb/dump_class_layout_unittest.py:
+ (serial_test_ClassWithPaddedBitfields):
+ (serial_test_MemberHasBitfieldPadding):
+ (serial_test_InheritsFromClassWithPaddedBitfields):
+ * lldb/lldbWebKitTester/DumpClassLayoutTesting.cpp:
+ (avoidClassDeadStripping):
+ * lldb/lldb_dump_class_layout.py:
+ (ClassLayoutBase):
+ (ClassLayoutBase._to_string_recursive):
+ (ClassLayout._parse):
+ (ClassLayout._compute_padding_recursive):
+
2018-07-09 Youenn Fablet <[email protected]>
StringView operator==(char*) should check the length of the string
Modified: trunk/Tools/lldb/dump_class_layout_unittest.py (233660 => 233661)
--- trunk/Tools/lldb/dump_class_layout_unittest.py 2018-07-09 22:30:40 UTC (rev 233660)
+++ trunk/Tools/lldb/dump_class_layout_unittest.py 2018-07-09 23:07:26 UTC (rev 233661)
@@ -108,7 +108,7 @@
+3 < 1> <PADDING: 1 byte>
+4 < 8> BoolMemberFirst memberClass
+4 < 1> bool boolMember
- +9 < 3> <PADDING: 3 bytes>
+ +5 < 3> <PADDING: 3 bytes>
+8 < 4> int intMember
Total byte size: 12
Total pad bytes: 4
@@ -196,7 +196,7 @@
+24 < 8> BasicClassLayout BasicClassLayout
+24 < 4> int intMember
+28 < 1> bool boolMember
- +45 < 3> <PADDING: 3 bytes>
+ +29 < 3> <PADDING: 3 bytes>
+32 < 4> int intMemberB
+36 < 4> <PADDING: 4 bytes>
+40 < 8> double derivedMember
@@ -221,9 +221,9 @@
+24 < 8> BasicClassLayout BasicClassLayout
+24 < 4> int intMember
+28 < 1> bool boolMember
- +45 < 3> <PADDING: 3 bytes>
+ +29 < 3> <PADDING: 3 bytes>
+32 < 4> int intMemberB
- +52 < 4> <PADDING: 4 bytes>
+ +36 < 4> <PADDING: 4 bytes>
+40 < 16> VirtualBase VirtualBase
+40 < 8> __vtbl_ptr_type * _vptr
+48 < 1> bool baseMember
@@ -251,7 +251,7 @@
+24 < 8> BasicClassLayout BasicClassLayout
+24 < 4> int intMember
+28 < 1> bool boolMember
- +45 < 3> <PADDING: 3 bytes>
+ +29 < 3> <PADDING: 3 bytes>
+32 < 4> int intMemberB
+36 < 4> <PADDING: 4 bytes>
+40 < 8> double derivedMember
@@ -298,16 +298,17 @@
def serial_test_ClassWithBitfields(self):
EXPECTED_RESULT = """ +0 < 12> ClassWithBitfields
+0 < 1> bool boolMember
- +1 < 4> unsigned int bitfield1 : 1
- +1 < 4> unsigned int bitfield2 : 2
- +1 < 4> unsigned int bitfield3 : 1
- +1 < 1> bool bitfield4 : 1
- +1 < 1> bool bitfield5 : 2
- +1 < 1> bool bitfield6 : 1
+ +1 < :1> unsigned int bitfield1 : 1
+ +1 < :2> unsigned int bitfield2 : 2
+ +1 < :1> unsigned int bitfield3 : 1
+ +1 < :1> bool bitfield4 : 1
+ +1 < :2> bool bitfield5 : 2
+ +1 < :1> bool bitfield6 : 1
+2 < 2> <PADDING: 2 bytes>
+4 < 4> int intMember
- +8 < 4> unsigned int bitfield7 : 1
- +8 < 1> bool bitfield8 : 1
+ +8 < :1> unsigned int bitfield7 : 1
+ +8 < :1> bool bitfield8 : 1
+ +8 < :6> <UNUSED BITS: 6 bits>
+9 < 3> <PADDING: 3 bytes>
Total byte size: 12
Total pad bytes: 5
@@ -314,3 +315,76 @@
Padding percentage: 41.67 %"""
actual_layout = debugger_instance.layout_for_classname('ClassWithBitfields')
self.assertEqual(EXPECTED_RESULT, actual_layout.as_string())
+
+ def serial_test_ClassWithPaddedBitfields(self):
+ EXPECTED_RESULT = """ +0 < 16> ClassWithPaddedBitfields
+ +0 < 1> bool boolMember
+ +1 < :1> unsigned int bitfield1 : 1
+ +1 < :1> bool bitfield2 : 1
+ +1 < :2> unsigned int bitfield3 : 2
+ +1 < :1> unsigned int bitfield4 : 1
+ +1 < :2> unsigned long bitfield5 : 2
+ +1 < :1> <UNUSED BITS: 1 bit>
+ +2 < 2> <PADDING: 2 bytes>
+ +4 < 4> int intMember
+ +8 < :1> unsigned int bitfield7 : 1
+ +8 < :9> unsigned int bitfield8 : 9
+ +9 < :1> bool bitfield9 : 1
+ +9 < :5> <UNUSED BITS: 5 bits>
+ +10 < 6> <PADDING: 6 bytes>
+Total byte size: 16
+Total pad bytes: 8
+Padding percentage: 50.00 %"""
+ actual_layout = debugger_instance.layout_for_classname('ClassWithPaddedBitfields')
+ self.assertEqual(EXPECTED_RESULT, actual_layout.as_string())
+
+ def serial_test_MemberHasBitfieldPadding(self):
+ EXPECTED_RESULT = """ +0 < 24> MemberHasBitfieldPadding
+ +0 < 16> ClassWithPaddedBitfields bitfieldMember
+ +0 < 1> bool boolMember
+ +1 < :1> unsigned int bitfield1 : 1
+ +1 < :1> bool bitfield2 : 1
+ +1 < :2> unsigned int bitfield3 : 2
+ +1 < :1> unsigned int bitfield4 : 1
+ +1 < :2> unsigned long bitfield5 : 2
+ +1 < :1> <UNUSED BITS: 1 bit>
+ +2 < 2> <PADDING: 2 bytes>
+ +4 < 4> int intMember
+ +8 < :1> unsigned int bitfield7 : 1
+ +8 < :9> unsigned int bitfield8 : 9
+ +9 < :1> bool bitfield9 : 1
+ +9 < :5> <UNUSED BITS: 5 bits>
+ +10 < 6> <PADDING: 6 bytes>
+ +16 < :1> bool bitfield1 : 1
+ +16 < :7> <UNUSED BITS: 7 bits>
+ +17 < 7> <PADDING: 7 bytes>
+Total byte size: 24
+Total pad bytes: 15
+Padding percentage: 62.50 %"""
+ actual_layout = debugger_instance.layout_for_classname('MemberHasBitfieldPadding')
+ self.assertEqual(EXPECTED_RESULT, actual_layout.as_string())
+
+ def serial_test_InheritsFromClassWithPaddedBitfields(self):
+ EXPECTED_RESULT = """ +0 < 16> InheritsFromClassWithPaddedBitfields
+ +0 < 16> ClassWithPaddedBitfields ClassWithPaddedBitfields
+ +0 < 1> bool boolMember
+ +1 < :1> unsigned int bitfield1 : 1
+ +1 < :1> bool bitfield2 : 1
+ +1 < :2> unsigned int bitfield3 : 2
+ +1 < :1> unsigned int bitfield4 : 1
+ +1 < :2> unsigned long bitfield5 : 2
+ +1 < :1> <UNUSED BITS: 1 bit>
+ +2 < 2> <PADDING: 2 bytes>
+ +4 < 4> int intMember
+ +8 < :1> unsigned int bitfield7 : 1
+ +8 < :9> unsigned int bitfield8 : 9
+ +9 < :1> bool bitfield9 : 1
+ +9 < :5> <UNUSED BITS: 5 bits>
+ +10 < :1> bool derivedBitfield : 1
+ +10 < :7> <UNUSED BITS: 7 bits>
+ +11 < 5> <PADDING: 5 bytes>
+Total byte size: 16
+Total pad bytes: 7
+Padding percentage: 43.75 %"""
+ actual_layout = debugger_instance.layout_for_classname('InheritsFromClassWithPaddedBitfields')
+ self.assertEqual(EXPECTED_RESULT, actual_layout.as_string())
Modified: trunk/Tools/lldb/lldbWebKitTester/DumpClassLayoutTesting.cpp (233660 => 233661)
--- trunk/Tools/lldb/lldbWebKitTester/DumpClassLayoutTesting.cpp 2018-07-09 22:30:40 UTC (rev 233660)
+++ trunk/Tools/lldb/lldbWebKitTester/DumpClassLayoutTesting.cpp 2018-07-09 23:07:26 UTC (rev 233661)
@@ -26,7 +26,6 @@
#include "DumpClassLayoutTesting.h"
#include <memory>
-#include <wtf/Optional.h>
/*
*** Dumping AST Record Layout
@@ -437,6 +436,83 @@
bool bitfield8 : 1;
};
+/*
+*** Dumping AST Record Layout
+ 0 | class ClassWithPaddedBitfields
+ 0 | _Bool boolMember
+ 1:0-0 | unsigned int bitfield1
+ 1:1-1 | _Bool bitfield2
+ 1:2-3 | unsigned int bitfield3
+ 1:4-4 | unsigned int bitfield4
+ 1:5-6 | unsigned long bitfield5
+ 4 | int intMember
+ 8:0-0 | unsigned int bitfield7
+ 8:1-9 | unsigned int bitfield8
+ 9:2-2 | _Bool bitfield9
+ | [sizeof=16, dsize=10, align=8,
+ | nvsize=10, nvalign=8]
+*/
+class ClassWithPaddedBitfields {
+ bool boolMember;
+
+ unsigned bitfield1 : 1;
+ bool bitfield2 : 1;
+ unsigned bitfield3 : 2;
+ unsigned bitfield4 : 1;
+ unsigned long bitfield5: 2;
+
+ int intMember;
+
+ unsigned bitfield7 : 1;
+ unsigned bitfield8 : 9;
+ bool bitfield9 : 1;
+};
+
+/*
+*** Dumping AST Record Layout
+ 0 | class MemberHasBitfieldPadding
+ 0 | class ClassWithPaddedBitfields bitfieldMember
+ 0 | _Bool boolMember
+ 1:0-0 | unsigned int bitfield1
+ 1:1-1 | _Bool bitfield2
+ 1:2-3 | unsigned int bitfield3
+ 1:4-4 | unsigned int bitfield4
+ 1:5-6 | unsigned long bitfield5
+ 4 | int intMember
+ 8:0-0 | unsigned int bitfield7
+ 8:1-9 | unsigned int bitfield8
+ 9:2-2 | _Bool bitfield9
+ 16:0-0 | _Bool bitfield1
+ | [sizeof=24, dsize=17, align=8,
+ | nvsize=17, nvalign=8]
+*/
+class MemberHasBitfieldPadding {
+ ClassWithPaddedBitfields bitfieldMember;
+ bool bitfield1 : 1;
+};
+
+/*
+*** Dumping AST Record Layout
+ 0 | class InheritsFromClassWithPaddedBitfields
+ 0 | class ClassWithPaddedBitfields (base)
+ 0 | _Bool boolMember
+ 1:0-0 | unsigned int bitfield1
+ 1:1-1 | _Bool bitfield2
+ 1:2-3 | unsigned int bitfield3
+ 1:4-4 | unsigned int bitfield4
+ 1:5-6 | unsigned long bitfield5
+ 4 | int intMember
+ 8:0-0 | unsigned int bitfield7
+ 8:1-9 | unsigned int bitfield8
+ 9:2-2 | _Bool bitfield9
+ 10:0-0 | _Bool derivedBitfield
+ | [sizeof=16, dsize=11, align=8,
+ | nvsize=11, nvalign=8]
+*/
+class InheritsFromClassWithPaddedBitfields : public ClassWithPaddedBitfields {
+ bool derivedBitfield : 1;
+};
+
void avoidClassDeadStripping()
{
BasicClassLayout basicClassInstance;
@@ -453,4 +529,7 @@
ClassWithClassMembers classWithClassMembersInstance;
ClassWithPointerMember classWithPointerMemberInstance;
ClassWithBitfields classWithBitfieldsInstance;
+ ClassWithPaddedBitfields classWithPaddedBitfieldsInstance;
+ MemberHasBitfieldPadding memberHasBitfieldPaddingInstance;
+ InheritsFromClassWithPaddedBitfields inheritsFromClassWithPaddedBitfieldsInstance;
}
Modified: trunk/Tools/lldb/lldb_dump_class_layout.py (233660 => 233661)
--- trunk/Tools/lldb/lldb_dump_class_layout.py 2018-07-09 22:30:40 UTC (rev 233660)
+++ trunk/Tools/lldb/lldb_dump_class_layout.py 2018-07-09 23:07:26 UTC (rev 233661)
@@ -50,9 +50,12 @@
MEMBER_CLASS_INSTANCE = 'class_instance'
MEMBER_BYTE_SIZE = 'byte_size'
MEMBER_OFFSET = 'offset' # offset is local to this class.
+ MEMBER_OFFSET_IN_BITS = 'offset_in_bits'
MEMBER_IS_BITFIELD = 'is_bitfield'
MEMBER_BITFIELD_BIT_SIZE = 'bit_size'
- PADDING_TYPE = '<PADDING>'
+ PADDING_BYTES_TYPE = 'padding'
+ PADDING_BITS_TYPE = 'padding_bits'
+ PADDING_BITS_SIZE = 'padding_bits_size'
PADDING_NAME = ''
def __init__(self, typename):
@@ -105,9 +108,13 @@
byte_size = data_member[self.MEMBER_BYTE_SIZE]
if self.MEMBER_IS_BITFIELD in data_member:
- str_list.append('%+4u <%3u> %s %s %s : %d' % (member_total_offset, byte_size, ' ' * depth, data_member[self.MEMBER_TYPE_KEY], data_member[self.MEMBER_NAME_KEY], data_member[self.MEMBER_BITFIELD_BIT_SIZE]))
- elif data_member[self.MEMBER_TYPE_KEY] == self.PADDING_TYPE:
+ num_bits = data_member[self.MEMBER_BITFIELD_BIT_SIZE]
+ str_list.append('%+4u < :%1u> %s %s %s : %d' % (member_total_offset, num_bits, ' ' * depth, data_member[self.MEMBER_TYPE_KEY], data_member[self.MEMBER_NAME_KEY], num_bits))
+ elif data_member[self.MEMBER_TYPE_KEY] == self.PADDING_BYTES_TYPE:
str_list.append('%+4u <%3u> %s %s<PADDING: %d %s>%s' % (member_total_offset, byte_size, ' ' * depth, warn_start, byte_size, 'bytes' if byte_size > 1 else 'byte', color_end))
+ elif data_member[self.MEMBER_TYPE_KEY] == self.PADDING_BITS_TYPE:
+ padding_bits = data_member[self.PADDING_BITS_SIZE]
+ str_list.append('%+4u < :%1u> %s %s<UNUSED BITS: %d %s>%s' % (member_total_offset, padding_bits, ' ' * depth, warn_start, padding_bits, 'bits' if padding_bits > 1 else 'bit', color_end))
else:
str_list.append('%+4u <%3u> %s %s %s' % (member_total_offset, byte_size, ' ' * depth, data_member[self.MEMBER_TYPE_KEY], data_member[self.MEMBER_NAME_KEY]))
@@ -231,6 +238,9 @@
if field.IsBitfield():
data_member[self.MEMBER_IS_BITFIELD] = True
data_member[self.MEMBER_BITFIELD_BIT_SIZE] = field.GetBitfieldSizeInBits()
+ data_member[self.MEMBER_OFFSET_IN_BITS] = field.GetOffsetInBits()
+ # For bitfields, member_byte_size was computed based on the field type without the bitfield modifiers, so compute from the number of bits.
+ data_member[self.MEMBER_BYTE_SIZE] = (field.GetBitfieldSizeInBits() + 7) / 8
elif member_type_class == lldb.eTypeClassStruct or member_type_class == lldb.eTypeClassClass:
nested_class = ClassLayout(self.target, member_type, self)
data_member[self.MEMBER_CLASS_INSTANCE] = nested_class
@@ -302,9 +312,9 @@
if padding_size > 0:
padding_member = {
self.MEMBER_NAME_KEY : self.PADDING_NAME,
- self.MEMBER_TYPE_KEY : self.PADDING_TYPE,
+ self.MEMBER_TYPE_KEY : self.PADDING_BYTES_TYPE,
self.MEMBER_BYTE_SIZE : padding_size,
- self.MEMBER_OFFSET : current_offset,
+ self.MEMBER_OFFSET : current_offset - start_offset,
}
self.data_members.insert(i, padding_member)
@@ -311,6 +321,26 @@
padding_bytes += padding_size
i += 1
+ if self.MEMBER_IS_BITFIELD in data_member:
+ next_member_is_bitfield = False
+ if i < len(self.data_members) - 1:
+ next_data_member = self.data_members[i + 1]
+ next_member_is_bitfield = self.MEMBER_IS_BITFIELD in next_data_member
+
+ if not next_member_is_bitfield:
+ end_bit_offset = data_member[self.MEMBER_OFFSET_IN_BITS] + data_member[self.MEMBER_BITFIELD_BIT_SIZE]
+ unused_bits = (8 - end_bit_offset) % 8
+ if unused_bits:
+ bit_padding_member = {
+ self.MEMBER_NAME_KEY : self.PADDING_NAME,
+ self.MEMBER_TYPE_KEY : self.PADDING_BITS_TYPE,
+ self.MEMBER_BYTE_SIZE : data_member[self.MEMBER_BYTE_SIZE],
+ self.PADDING_BITS_SIZE : unused_bits,
+ self.MEMBER_OFFSET : data_member[self.MEMBER_OFFSET],
+ }
+ self.data_members.insert(i + 1, bit_padding_member)
+ i += 1
+
current_offset = start_offset + member_offset
if self.MEMBER_CLASS_INSTANCE in data_member:
@@ -328,9 +358,9 @@
if padding_size > 0:
padding_member = {
self.MEMBER_NAME_KEY : self.PADDING_NAME,
- self.MEMBER_TYPE_KEY : self.PADDING_TYPE,
+ self.MEMBER_TYPE_KEY : self.PADDING_BYTES_TYPE,
self.MEMBER_BYTE_SIZE : padding_size,
- self.MEMBER_OFFSET : current_offset,
+ self.MEMBER_OFFSET : current_offset - start_offset,
}
self.data_members.append(padding_member)
padding_bytes += padding_size
