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author | Tom Tromey <tom@tromey.com> | 2018-05-12 17:04:50 -0600 |
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committer | Tom Tromey <tom@tromey.com> | 2018-05-18 13:20:39 -0600 |
commit | ce1e8424c69793139ec8d2a60c4a21ab136ae9e0 (patch) | |
tree | e642c608031d0e1489652facc7a2378a7041545e /gdb/c-typeprint.c | |
parent | 7b4ae824289504c173a597e86a00ceab452095b7 (diff) | |
download | fsf-binutils-gdb-ce1e8424c69793139ec8d2a60c4a21ab136ae9e0.zip fsf-binutils-gdb-ce1e8424c69793139ec8d2a60c4a21ab136ae9e0.tar.gz fsf-binutils-gdb-ce1e8424c69793139ec8d2a60c4a21ab136ae9e0.tar.bz2 |
Show padding in ptype/o output
I was recently using ptype/o to look at the layout of some objects in
gdb. I noticed that trailing padding was not shown -- but I wanted to
be able to look at that, too.
This patch changes ptype/o to also print trailing holes.
Tested on x86-64 Fedora 26.
gdb/ChangeLog
2018-05-18 Tom Tromey <tom@tromey.com>
* c-typeprint.c (maybe_print_hole): New function.
(c_print_type_struct_field_offset): Update.
(c_type_print_base_struct_union): Call maybe_print_hole.
gdb/testsuite/ChangeLog
2018-05-18 Tom Tromey <tom@tromey.com>
* gdb.base/ptype-offsets.exp: Update.
Diffstat (limited to 'gdb/c-typeprint.c')
-rw-r--r-- | gdb/c-typeprint.c | 62 |
1 files changed, 40 insertions, 22 deletions
diff --git a/gdb/c-typeprint.c b/gdb/c-typeprint.c index 1a8af78..cb793f0 100644 --- a/gdb/c-typeprint.c +++ b/gdb/c-typeprint.c @@ -937,6 +937,42 @@ c_print_type_union_field_offset (struct type *type, unsigned int field_idx, fprintf_filtered (stream, "/* %4u */", TYPE_LENGTH (ftype)); } +/* Helper function for ptype/o implementation that prints information + about a hole, if necessary. STREAM is where to print. BITPOS is + the bitpos of the current field. PODATA is the offset-printing + state. FOR_WHAT is a string describing the purpose of the + hole. */ + +static void +maybe_print_hole (struct ui_file *stream, unsigned int bitpos, + struct print_offset_data *podata, const char *for_what) +{ + /* We check for PODATA->END_BITPOS > 0 because there is a specific + scenario when PODATA->END_BITPOS can be zero and BITPOS can be > + 0: when we are dealing with a struct/class with a virtual method. + Because of the vtable, the first field of the struct/class will + have an offset of sizeof (void *) (the size of the vtable). If + we do not check for PODATA->END_BITPOS > 0 here, GDB will report + a hole before the first field, which is not accurate. */ + if (podata->end_bitpos > 0 && podata->end_bitpos < bitpos) + { + /* If PODATA->END_BITPOS is smaller than the current type's + bitpos, it means there's a hole in the struct, so we report + it here. */ + unsigned int hole = bitpos - podata->end_bitpos; + unsigned int hole_byte = hole / TARGET_CHAR_BIT; + unsigned int hole_bit = hole % TARGET_CHAR_BIT; + + if (hole_bit > 0) + fprintf_filtered (stream, "/* XXX %2u-bit %s */\n", hole_bit, + for_what); + + if (hole_byte > 0) + fprintf_filtered (stream, "/* XXX %2u-byte %s */\n", hole_byte, + for_what); + } +} + /* Print information about field at index FIELD_IDX of the struct type TYPE. @@ -963,28 +999,7 @@ c_print_type_struct_field_offset (struct type *type, unsigned int field_idx, unsigned int fieldsize_byte = TYPE_LENGTH (ftype); unsigned int fieldsize_bit = fieldsize_byte * TARGET_CHAR_BIT; - /* We check for PODATA->END_BITPOS > 0 because there is a specific - scenario when PODATA->END_BITPOS can be zero and BITPOS can be > - 0: when we are dealing with a struct/class with a virtual method. - Because of the vtable, the first field of the struct/class will - have an offset of sizeof (void *) (the size of the vtable). If - we do not check for PODATA->END_BITPOS > 0 here, GDB will report - a hole before the first field, which is not accurate. */ - if (podata->end_bitpos > 0 && podata->end_bitpos < bitpos) - { - /* If PODATA->END_BITPOS is smaller than the current type's - bitpos, it means there's a hole in the struct, so we report - it here. */ - unsigned int hole = bitpos - podata->end_bitpos; - unsigned int hole_byte = hole / TARGET_CHAR_BIT; - unsigned int hole_bit = hole % TARGET_CHAR_BIT; - - if (hole_bit > 0) - fprintf_filtered (stream, "/* XXX %2u-bit hole */\n", hole_bit); - - if (hole_byte > 0) - fprintf_filtered (stream, "/* XXX %2u-byte hole */\n", hole_byte); - } + maybe_print_hole (stream, bitpos, podata, "hole"); if (TYPE_FIELD_PACKED (type, field_idx)) { @@ -1508,6 +1523,9 @@ c_type_print_base_struct_union (struct type *type, struct ui_file *stream, { if (show > 0) { + unsigned int bitpos = TYPE_LENGTH (type) * TARGET_CHAR_BIT; + maybe_print_hole (stream, bitpos, podata, "padding"); + fputs_filtered ("\n", stream); print_spaces_filtered_with_print_options (level + 4, stream, |