From dc53a7adb516adbf2f646a078a1140b1044a39f5 Mon Sep 17 00:00:00 2001 From: Joel Brobecker Date: Wed, 29 Jan 2014 17:39:56 +0400 Subject: DWARF: Add array DW_AT_bit_stride and DW_AT_byte_stride support Consider the following declarations in Ada... type Item is range -32 .. 31; for Item'Size use 6; type Table is array (Natural range 0 .. 4) of Item; pragma Pack (Table); ... which declare a packed array whose elements are 6 bits long. The debugger currently does not notice that the array is packed, and thus prints values of this type incorrectly. This can be seen in the "ptype" output: (gdb) ptype table type = array (0 .. 4) of foo.item Normally, the debugger should print: (gdb) ptype table type = array (0 .. 4) of foo.item The debugging information for this array looks like this: .uleb128 0xf # (DIE (0x15c) DW_TAG_array_type) .long .LASF9 # DW_AT_name: "pck__table" .byte 0x6 # DW_AT_bit_stride .long 0x1a9 # DW_AT_type .uleb128 0x10 # (DIE (0x16a) DW_TAG_subrange_type) .long 0x3b # DW_AT_type .byte 0 # DW_AT_lower_bound .byte 0x4 # DW_AT_upper_bound .byte 0 # end of children of DIE 0x15c The interesting part is the DW_AT_bit_stride attribute, which tells the size of the array elements is 6 bits, rather than the normal element type's size. This patch adds support for this attribute by first creating gdbtypes.c::create_array_type_with_stride, which is an enhanced version of create_array_type taking an extra parameter as the stride. The old create_array_type can then be re-implemented very simply by calling the new create_array_type_with_stride. We can then use this new function from dwarf2read, to create arrays with or without stride. gdb/ChangeLog: * gdbtypes.h (create_array_type_with_stride): Add declaration. * gdbtypes.c (create_array_type_with_stride): New function, renaming create_array_type, but with an added parameter called "bit_stride". (create_array_type): Re-implement using create_array_type_with_stride. * dwarf2read.c (read_array_type): Add support for DW_AT_byte_stride and DW_AT_bit_stride attributes. gdb/testsuite/ChangeLog: * gdb.dwarf2/arr-stride.c: New file. * gdb.dwarf2/arr-stride.exp: New file. The test, relying purely on generating an assembly file, only verifies the type description of our array. But I was also able to verify manually that the debugger print values of these types correctly as well (which was not the case prior to this patch). --- gdb/dwarf2read.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) (limited to 'gdb/dwarf2read.c') diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c index 3eaa0b1..d7dc38c 100644 --- a/gdb/dwarf2read.c +++ b/gdb/dwarf2read.c @@ -13281,6 +13281,7 @@ read_array_type (struct die_info *die, struct dwarf2_cu *cu) int ndim = 0; struct cleanup *back_to; const char *name; + unsigned int bit_stride = 0; element_type = die_type (die, cu); @@ -13289,13 +13290,22 @@ read_array_type (struct die_info *die, struct dwarf2_cu *cu) if (type) return type; + attr = dwarf2_attr (die, DW_AT_byte_stride, cu); + if (attr != NULL) + bit_stride = DW_UNSND (attr) * 8; + + attr = dwarf2_attr (die, DW_AT_bit_stride, cu); + if (attr != NULL) + bit_stride = DW_UNSND (attr); + /* Irix 6.2 native cc creates array types without children for arrays with unspecified length. */ if (die->child == NULL) { index_type = objfile_type (objfile)->builtin_int; range_type = create_range_type (NULL, index_type, 0, -1); - type = create_array_type (NULL, element_type, range_type); + type = create_array_type_with_stride (NULL, element_type, range_type, + bit_stride); return set_die_type (die, type, cu); } @@ -13335,12 +13345,14 @@ read_array_type (struct die_info *die, struct dwarf2_cu *cu) int i = 0; while (i < ndim) - type = create_array_type (NULL, type, range_types[i++]); + type = create_array_type_with_stride (NULL, type, range_types[i++], + bit_stride); } else { while (ndim-- > 0) - type = create_array_type (NULL, type, range_types[ndim]); + type = create_array_type_with_stride (NULL, type, range_types[ndim], + bit_stride); } /* Understand Dwarf2 support for vector types (like they occur on -- cgit v1.1