From: Tom Tromey Date: Sat, 12 May 2018 23:04:50 +0000 (-0600) Subject: Show padding in ptype/o output X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=ce1e8424c69793139ec8d2a60c4a21ab136ae9e0;p=binutils-gdb.git 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 * 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 * gdb.base/ptype-offsets.exp: Update. --- diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 263ce8172fc..d4d00f8328e 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2018-05-18 Tom Tromey + + * 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. + 2018-05-17 Keith Seitz * breakpoint.c (build_bpstat_chain): New function, moved from diff --git a/gdb/c-typeprint.c b/gdb/c-typeprint.c index 1a8af786698..cb793f0770d 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, diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index 54fec1c8f0c..cdd4ba9fa90 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2018-05-18 Tom Tromey + + * gdb.base/ptype-offsets.exp: Update. + 2018-05-17 Keith Seitz * gdb.ada/bp_inlined_func.exp: Update inlined frame locations diff --git a/gdb/testsuite/gdb.base/ptype-offsets.exp b/gdb/testsuite/gdb.base/ptype-offsets.exp index 003e294a745..d8718d581b1 100644 --- a/gdb/testsuite/gdb.base/ptype-offsets.exp +++ b/gdb/testsuite/gdb.base/ptype-offsets.exp @@ -52,6 +52,7 @@ gdb_test "ptype /o struct abc" \ { /\* total size \(bytes\): 8 \*/} \ { \} field8;} \ {/\* 48 | 4 \*/ my_int_type field9;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 56 \*/} \ { \}}] @@ -81,6 +82,7 @@ gdb_test "ptype /oTM struct abc" \ { ~abc\(\);} \ {} \ { typedef int my_int_type;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 56 \*/} \ { \}}] @@ -105,6 +107,7 @@ gdb_test "ptype /TMo struct abc" \ { /\* total size \(bytes\): 8 \*/} \ { \} field8;} \ {/\* 48 | 4 \*/ my_int_type field9;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 56 \*/} \ { \}}] @@ -133,6 +136,7 @@ gdb_test "ptype /o struct pqr" \ { \} ff2;} \ {/\* XXX 28-byte hole \*/} \ {/\* 72 | 1 \*/ signed char ff3;} \ +{/\* XXX 7-byte padding \*/} \ {} \ { /\* total size \(bytes\): 56 \*/} \ { \}}] @@ -148,6 +152,7 @@ gdb_test "ptype /o union qwe" \ {/\* XXX 4-byte hole \*/} \ {/\* 8 | 8 \*/ signed char \*a2;} \ {/\* 16 | 4 \*/ int a3;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 24 \*/} \ { \} fff1;} \ @@ -161,6 +166,7 @@ gdb_test "ptype /o union qwe" \ {/\* XXX 4-byte hole \*/} \ {/\* 24 | 8 \*/ signed char \*a2;} \ {/\* 32 | 4 \*/ int a3;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 24 \*/} \ { \} f4;} \ @@ -184,6 +190,7 @@ gdb_test "ptype /o struct poi" \ {/\* XXX 4-byte hole \*/} \ {/\* 16 | 8 \*/ signed char \*a2;} \ {/\* 24 | 4 \*/ int a3;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 24 \*/} \ { \} fff1;} \ @@ -197,9 +204,11 @@ gdb_test "ptype /o struct poi" \ {/\* XXX 4-byte hole \*/} \ {/\* 32 | 8 \*/ signed char \*a2;} \ {/\* 40 | 4 \*/ int a3;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 24 \*/} \ { \} f4;} \ +{/\* XXX 32-byte padding \*/} \ {} \ { /\* total size \(bytes\): 40 \*/} \ { \} fff2;} \ @@ -221,6 +230,7 @@ gdb_test "ptype /o struct poi" \ {/\* XXX 4-byte hole \*/} \ {/\* 112 | 8 \*/ signed char \*a2;} \ {/\* 120 | 4 \*/ int a3;} \ +{/\* XXX 4-byte padding \*/} \ {} \ { /\* total size \(bytes\): 24 \*/} \ { \} f4;} \ @@ -228,6 +238,7 @@ gdb_test "ptype /o struct poi" \ { /\* total size \(bytes\): 40 \*/} \ { \} ff2;} \ {/\* 152 | 1 \*/ signed char ff3;} \ +{/\* XXX 7-byte padding \*/} \ {} \ { /\* total size \(bytes\): 56 \*/} \ { \} f4;} \ @@ -262,6 +273,7 @@ gdb_test "ptype /o struct tyu" \ {/\* 8 | 8 \*/ int64_t a5;} \ {/\* 16:27 | 4 \*/ int a6 : 5;} \ {/\* 16:56 | 8 \*/ int64_t a7 : 3;} \ +{/\* XXX 7-byte padding \*/} \ {} \ { /\* total size \(bytes\): 24 \*/} \ { \}}]