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[binutils-gdb] Show padding in ptype/o output
- From: Tom Tromey <tromey at sourceware dot org>
- To: gdb-cvs at sourceware dot org
- Date: 18 May 2018 19:31:52 -0000
- Subject: [binutils-gdb] Show padding in ptype/o output
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ce1e8424c69793139ec8d2a60c4a21ab136ae9e0
commit ce1e8424c69793139ec8d2a60c4a21ab136ae9e0
Author: Tom Tromey <tom@tromey.com>
Date: Sat May 12 17:04:50 2018 -0600
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.
Diff:
---
gdb/ChangeLog | 6 ++++
gdb/c-typeprint.c | 62 ++++++++++++++++++++------------
gdb/testsuite/ChangeLog | 4 +++
gdb/testsuite/gdb.base/ptype-offsets.exp | 12 +++++++
4 files changed, 62 insertions(+), 22 deletions(-)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 263ce81..d4d00f8 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+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.
+
2018-05-17 Keith Seitz <keiths@redhat.com>
* breakpoint.c (build_bpstat_chain): New function, moved from
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,
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 54fec1c..cdd4ba9 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2018-05-18 Tom Tromey <tom@tromey.com>
+
+ * gdb.base/ptype-offsets.exp: Update.
+
2018-05-17 Keith Seitz <keiths@redhat.com>
* 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 003e294..d8718d5 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 \*/} \
{ \}}]