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| author | Tom Tromey <tromey@adacore.com> | 2019-04-29 09:55:56 -0600 |
|---|---|---|
| committer | Tom Tromey <tromey@adacore.com> | 2019-05-08 10:15:51 -0600 |
| commit | 9d3421afbb9f3cfc8e67366ba75ea12ed8f732a3 (patch) | |
| tree | 66eb6aba210e07f4f76b979c07687598d477dcea /gdb/testsuite | |
| parent | 844333e24966817fe4d622494a75c8ae0acdb91f (diff) | |
| download | gdb-9d3421afbb9f3cfc8e67366ba75ea12ed8f732a3.zip gdb-9d3421afbb9f3cfc8e67366ba75ea12ed8f732a3.tar.gz gdb-9d3421afbb9f3cfc8e67366ba75ea12ed8f732a3.tar.bz2 | |
Change ptype/o to print bit offset
Consider this short C example:
struct inner
{
unsigned x;
unsigned y : 3;
unsigned z : 3;
};
struct outer
{
unsigned char o : 3;
struct inner i __attribute__ ((packed));
};
When I use "ptype/o" on this, I get:
(gdb) ptype/o struct outer
/* offset | size */ type = struct outer {
/* 0: 5 | 1 */ unsigned char o : 3;
/* XXX 5-bit hole */
/* 1 | 8 */ struct inner {
/* 1 | 4 */ unsigned int x;
/* 5:29 | 4 */ unsigned int y : 3;
/* 5:26 | 4 */ unsigned int z : 3;
/* XXX 2-bit padding */
/* XXX 3-byte padding */
/* total size (bytes): 8 */
} i;
/* total size (bytes): 9 */
}
In the location of "o" ("0: 5"), the "5" means "there are 5 bits left
relative to the size of the underlying type.
I find this very difficult to follow. On irc, Sergio said that this
choice came because it is what pahole does. However, I think it's not
very useful, and maybe is just an artifact of the way that
DW_AT_bit_offset was defined in DWARF 3.
This patch changes ptype/o to print the offset of a bitfield in a more
natural way, that is, using the bit number according to the platform's
bit numbering.
With this patch, the output is now:
(gdb) ptype/o struct outer
/* offset | size */ type = struct outer {
/* 0: 0 | 1 */ unsigned char o : 3;
/* XXX 5-bit hole */
/* 1 | 8 */ struct inner {
/* 1 | 4 */ unsigned int x;
/* 5: 0 | 4 */ unsigned int y : 3;
/* 5: 3 | 4 */ unsigned int z : 3;
/* XXX 2-bit padding */
/* XXX 3-byte padding */
/* total size (bytes): 8 */
} i;
/* total size (bytes): 9 */
}
This is better, IMO, because now the "offset" of a bitfield is
consistent with the offset of an ordinary member, referring to its
offset from the start of the structure.
gdb/ChangeLog
2019-05-08 Tom Tromey <tromey@adacore.com>
* typeprint.c (print_offset_data::update): Print the bit offset,
not the number of bits remaining.
gdb/doc/ChangeLog
2019-05-08 Tom Tromey <tromey@adacore.com>
* gdb.texinfo (Symbols): Document change to ptype/o.
gdb/testsuite/ChangeLog
2019-05-08 Tom Tromey <tromey@adacore.com>
* gdb.base/ptype-offsets.exp: Update tests.
Diffstat (limited to 'gdb/testsuite')
| -rw-r--r-- | gdb/testsuite/ChangeLog | 4 | ||||
| -rw-r--r-- | gdb/testsuite/gdb.base/ptype-offsets.exp | 30 |
2 files changed, 19 insertions, 15 deletions
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index eb1110e..6b51db8 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,5 +1,9 @@ 2019-05-08 Tom Tromey <tromey@adacore.com> + * gdb.base/ptype-offsets.exp: Update tests. + +2019-05-08 Tom Tromey <tromey@adacore.com> + * gdb.base/ptype-offsets.exp: Use string_to_regexp. Fix test cases. * gdb.base/ptype-offsets.cc (struct abc) <my_int_type>: Now diff --git a/gdb/testsuite/gdb.base/ptype-offsets.exp b/gdb/testsuite/gdb.base/ptype-offsets.exp index 12b3a74..6116520 100644 --- a/gdb/testsuite/gdb.base/ptype-offsets.exp +++ b/gdb/testsuite/gdb.base/ptype-offsets.exp @@ -38,7 +38,7 @@ gdb_test "ptype /o struct abc" \ "/* offset | size */ type = struct abc \{" \ " public:" \ "/* 8 | 8 */ void *field1;" \ -"/* 16:31 | 4 */ unsigned int field2 : 1;" \ +"/* 16: 0 | 4 */ unsigned int field2 : 1;" \ "/* XXX 7-bit hole */" \ "/* XXX 3-byte hole */" \ "/* 20 | 4 */ int field3;" \ @@ -63,7 +63,7 @@ gdb_test "ptype /oTM struct abc" \ "/* offset | size */ type = struct abc \{" \ " public:" \ "/* 8 | 8 */ void *field1;" \ -"/* 16:31 | 4 */ unsigned int field2 : 1;" \ +"/* 16: 0 | 4 */ unsigned int field2 : 1;" \ "/* XXX 7-bit hole */" \ "/* XXX 3-byte hole */" \ "/* 20 | 4 */ int field3;" \ @@ -93,7 +93,7 @@ gdb_test "ptype /TMo struct abc" \ "/* offset | size */ type = struct abc \{" \ " public:" \ "/* 8 | 8 */ void *field1;" \ -"/* 16:31 | 4 */ unsigned int field2 : 1;" \ +"/* 16: 0 | 4 */ unsigned int field2 : 1;" \ "/* XXX 7-bit hole */" \ "/* XXX 3-byte hole */" \ "/* 20 | 4 */ int field3;" \ @@ -264,15 +264,15 @@ gdb_test "ptype /o struct poi" \ gdb_test "ptype /o struct tyu" \ [string_to_regexp [multi_line \ "/* offset | size */ type = struct tyu \{" \ -"/* 0:31 | 4 */ int a1 : 1;" \ -"/* 0:28 | 4 */ int a2 : 3;" \ -"/* 0: 5 | 4 */ int a3 : 23;" \ +"/* 0: 0 | 4 */ int a1 : 1;" \ +"/* 0: 1 | 4 */ int a2 : 3;" \ +"/* 0: 4 | 4 */ int a3 : 23;" \ "/* 3: 3 | 1 */ signed char a4 : 2;" \ "/* XXX 3-bit hole */" \ "/* XXX 4-byte hole */" \ "/* 8 | 8 */ int64_t a5;" \ -"/* 16:27 | 4 */ int a6 : 5;" \ -"/* 16:56 | 8 */ int64_t a7 : 3;" \ +"/* 16: 0 | 4 */ int a6 : 5;" \ +"/* 16: 5 | 8 */ int64_t a7 : 3;" \ "/* XXX 7-byte padding */" \ "" \ " /* total size (bytes): 24 */" \ @@ -293,8 +293,8 @@ gdb_test "ptype /o struct asd" \ "" \ " /* total size (bytes): 8 */" \ " \} f3;" \ -"/* 24:27 | 4 */ int f4 : 5;" \ -"/* 24:26 | 4 */ unsigned int f5 : 1;" \ +"/* 24: 0 | 4 */ int f4 : 5;" \ +"/* 24: 5 | 4 */ unsigned int f5 : 1;" \ "/* XXX 2-bit hole */" \ "/* XXX 1-byte hole */" \ "/* 26 | 2 */ short f6;" \ @@ -304,11 +304,11 @@ gdb_test "ptype /o struct asd" \ " \} f7;" \ "/* 32 | 8 */ unsigned long f8;" \ "/* 40 | 8 */ signed char *f9;" \ -"/* 48:28 | 4 */ int f10 : 4;" \ -"/* 48:27 | 4 */ unsigned int f11 : 1;" \ -"/* 48:26 | 4 */ unsigned int f12 : 1;" \ -"/* 48:25 | 4 */ unsigned int f13 : 1;" \ -"/* 48:24 | 4 */ unsigned int f14 : 1;" \ +"/* 48: 0 | 4 */ int f10 : 4;" \ +"/* 48: 4 | 4 */ unsigned int f11 : 1;" \ +"/* 48: 5 | 4 */ unsigned int f12 : 1;" \ +"/* 48: 6 | 4 */ unsigned int f13 : 1;" \ +"/* 48: 7 | 4 */ unsigned int f14 : 1;" \ "/* XXX 7-byte hole */" \ "/* 56 | 8 */ void *f15;" \ "/* 64 | 8 */ void *f16;" \ |