Translates structure members with DW_AT_data_bit_offset set in DWARF
into LF_BITFIELD symbols.
gcc/
* dwarf2codeview.cc
(struct codeview_custom_type): Add lf_bitfield to union.
(write_lf_bitfield): New function.
(write_custom_types): Call write_lf_bitfield.
(create_bitfield): New function.
(get_type_num_struct): Handle bitfields.
* dwarf2codeview.h (LF_BITFIELD): Define.
---
gcc/dwarf2codeview.cc | 89 ++++++++++++++++++++++++++++++++++++++++++-
gcc/dwarf2codeview.h | 1 +
2 files changed, 88 insertions(+), 2 deletions(-)
diff --git a/gcc/dwarf2codeview.cc b/gcc/dwarf2codeview.cc
index 3f1ce5577fc..06267639169 100644
--- a/gcc/dwarf2codeview.cc
+++ b/gcc/dwarf2codeview.cc
@@ -256,6 +256,12 @@ struct codeview_custom_type
uint32_t index_type;
codeview_integer length_in_bytes;
} lf_array;
+ struct
+ {
+ uint32_t base_type;
+ uint8_t length;
+ uint8_t position;
+ } lf_bitfield;
};
};
@@ -1573,6 +1579,50 @@ write_lf_array (codeview_custom_type *t)
asm_fprintf (asm_out_file, "%LLcv_type%x_end:\n", t->num);
}
+/* Write an LF_BITFIELD type. */
+
+static void
+write_lf_bitfield (codeview_custom_type *t)
+{
+ /* This is lf_bitfield in binutils and lfBitfield in Microsoft's cvinfo.h:
+
+ struct lf_bitfield
+ {
+ uint16_t size;
+ uint16_t kind;
+ uint32_t base_type;
+ uint8_t length;
+ uint8_t position;
+ } ATTRIBUTE_PACKED;
+ */
+
+ fputs (integer_asm_op (2, false), asm_out_file);
+ asm_fprintf (asm_out_file, "%LLcv_type%x_end - %LLcv_type%x_start\n",
+ t->num, t->num);
+
+ asm_fprintf (asm_out_file, "%LLcv_type%x_start:\n", t->num);
+
+ fputs (integer_asm_op (2, false), asm_out_file);
+ fprint_whex (asm_out_file, t->kind);
+ putc ('\n', asm_out_file);
+
+ fputs (integer_asm_op (4, false), asm_out_file);
+ fprint_whex (asm_out_file, t->lf_bitfield.base_type);
+ putc ('\n', asm_out_file);
+
+ fputs (integer_asm_op (1, false), asm_out_file);
+ fprint_whex (asm_out_file, t->lf_bitfield.length);
+ putc ('\n', asm_out_file);
+
+ fputs (integer_asm_op (1, false), asm_out_file);
+ fprint_whex (asm_out_file, t->lf_bitfield.position);
+ putc ('\n', asm_out_file);
+
+ write_cv_padding (2);
+
+ asm_fprintf (asm_out_file, "%LLcv_type%x_end:\n", t->num);
+}
+
/* Write the .debug$T section, which contains all of our custom type
definitions. */
@@ -1619,6 +1669,10 @@ write_custom_types (void)
case LF_ARRAY:
write_lf_array (custom_types);
break;
+
+ case LF_BITFIELD:
+ write_lf_bitfield (custom_types);
+ break;
}
free (custom_types);
@@ -2199,6 +2253,33 @@ add_struct_forward_def (dw_die_ref type)
return ct->num;
}
+/* Add an LF_BITFIELD type, returning its number. DWARF represents bitfields
+ as members in a struct with a DW_AT_data_bit_offset attribute, whereas in
+ CodeView they're a distinct type. */
+
+static uint32_t
+create_bitfield (dw_die_ref c)
+{
+ codeview_custom_type *ct;
+ uint32_t base_type;
+
+ base_type = get_type_num (get_AT_ref (c, DW_AT_type), true, false);
+ if (base_type == 0)
+ return 0;
+
+ ct = (codeview_custom_type *) xmalloc (sizeof (codeview_custom_type));
+
+ ct->next = NULL;
+ ct->kind = LF_BITFIELD;
+ ct->lf_bitfield.base_type = base_type;
+ ct->lf_bitfield.length = get_AT_unsigned (c, DW_AT_bit_size);
+ ct->lf_bitfield.position = get_AT_unsigned (c, DW_AT_data_bit_offset);
+
+ add_custom_type (ct);
+
+ return ct->num;
+}
+
/* Process a DW_TAG_structure_type, DW_TAG_class_type, or DW_TAG_union_type
DIE, add an LF_FIELDLIST and an LF_STRUCTURE / LF_CLASS / LF_UNION type,
and return the number of the latter. */
@@ -2279,8 +2360,12 @@ get_type_num_struct (dw_die_ref type, bool in_struct,
bool *is_fwd_ref)
break;
}
- el->lf_member.type = get_type_num (get_AT_ref (c, DW_AT_type), true,
- false);
+ if (get_AT (c, DW_AT_data_bit_offset))
+ el->lf_member.type = create_bitfield (c);
+ else
+ el->lf_member.type = get_type_num (get_AT_ref (c, DW_AT_type),
+ true, false);
+
el->lf_member.offset.neg = false;
el->lf_member.offset.num = get_AT_unsigned (c,
DW_AT_data_member_location);
diff --git a/gcc/dwarf2codeview.h b/gcc/dwarf2codeview.h
index 70eed6bf2aa..70eae554b80 100644
--- a/gcc/dwarf2codeview.h
+++ b/gcc/dwarf2codeview.h
@@ -64,6 +64,7 @@ along with GCC; see the file COPYING3. If not see
#define LF_MODIFIER 0x1001
#define LF_POINTER 0x1002
#define LF_FIELDLIST 0x1203
+#define LF_BITFIELD 0x1205
#define LF_INDEX 0x1404
#define LF_ENUMERATE 0x1502
#define LF_ARRAY 0x1503
--
2.44.2
