This is the mail archive of the
binutils@sourceware.org
mailing list for the binutils project.
[Patch 4/6] ARM attributes: defaultless attributes
- From: Andrew Stubbs <ams at codesourcery dot com>
- To: binutils at sourceware dot org
- Date: Tue, 13 Jan 2009 10:01:53 +0000
- Subject: [Patch 4/6] ARM attributes: defaultless attributes
The attached patch adds a new flag for the attribute type. This flag
indicates that the attribute does not have a default value.
What this means is that, when the tools write the attributes to the
output, they will not suppress the attribute if it has a zero value.
Since attributes only have a type (and therefore a no-default flag) if
they have been read from somewhere, they are still only written if they
are present.
The only attribute that needs this feature is Tag_nodefaults that is
considered set if it exists, and the value is ignored. (Note that that
"no defaults" in its name is a coincidence, and the important thing here
is that the value can be (should be) zero.)
OK?
Andrew
2009-01-12 Andrew Stubbs <ams@codesourcery.com>
bfd/
* elf-attrs.c (is_default_attr): Support defaultless attributes.
(bfd_elf_add_obj_attr_int): Get type from _bfd_elf_obj_attrs_arg_type.
(bfd_elf_add_obj_attr_string): Likewise.
(bfd_elf_add_obj_attr_int_string): Likewise.
(_bfd_elf_parse_attributes): Allow for unknown flag bits in type.
* elf-bfd.h (struct obj_attribute): Document new flag bit.
* elf32-arm.c (elf32_arm_obj_attrs_arg_type): Specify that
Tag_nodefaults has no default value.
(elf32_arm_merge_eabi_attributes): Modify the Tag_nodefaults
comment to reflect the new state.
gas/
* read.c (s_vendor_attribute): Allow for unknown flag bits in type.
---
bfd/elf-attrs.c | 10 ++++++----
bfd/elf-bfd.h | 3 ++-
bfd/elf32-arm.c | 11 ++++++-----
gas/read.c | 4 ++--
4 files changed, 16 insertions(+), 12 deletions(-)
Index: bfd/elf-attrs.c
===================================================================
--- bfd/elf-attrs.c.orig
+++ bfd/elf-attrs.c
@@ -47,6 +47,8 @@ is_default_attr (obj_attribute *attr)
return FALSE;
if ((attr->type & 2) && attr->s && *attr->s)
return FALSE;
+ if (attr->type & 4)
+ return FALSE;
return TRUE;
}
@@ -290,7 +292,7 @@ bfd_elf_add_obj_attr_int (bfd *abfd, int
obj_attribute *attr;
attr = elf_new_obj_attr (abfd, vendor, tag);
- attr->type = 1;
+ attr->type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
attr->i = i;
}
@@ -313,7 +315,7 @@ bfd_elf_add_obj_attr_string (bfd *abfd,
obj_attribute *attr;
attr = elf_new_obj_attr (abfd, vendor, tag);
- attr->type = 2;
+ attr->type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
attr->s = _bfd_elf_attr_strdup (abfd, s);
}
@@ -325,7 +327,7 @@ bfd_elf_add_obj_attr_int_string (bfd *ab
obj_attribute *attr;
attr = elf_new_obj_attr (abfd, vendor, tag);
- attr->type = 3;
+ attr->type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
attr->i = i;
attr->s = _bfd_elf_attr_strdup (abfd, s);
}
@@ -487,7 +489,7 @@ _bfd_elf_parse_attributes (bfd *abfd, El
tag = read_unsigned_leb128 (abfd, p, &n);
p += n;
type = _bfd_elf_obj_attrs_arg_type (abfd, vendor, tag);
- switch (type)
+ switch (type & 3)
{
case 3:
val = read_unsigned_leb128 (abfd, p, &n);
Index: bfd/elf-bfd.h
===================================================================
--- bfd/elf-bfd.h.orig
+++ bfd/elf-bfd.h
@@ -1375,7 +1375,8 @@ struct elf_find_verdep_info
/* The value of an object attribute. type & 1 indicates whether there
is an integer value; type & 2 indicates whether there is a string
- value. */
+ value; type & 4 indicates whether the type has a default value
+ (i.e. is there a value that need not be written to file). */
typedef struct obj_attribute
{
Index: bfd/elf32-arm.c
===================================================================
--- bfd/elf32-arm.c.orig
+++ bfd/elf32-arm.c
@@ -8135,6 +8135,8 @@ elf32_arm_obj_attrs_arg_type (int tag)
{
if (tag == Tag_compatibility)
return 3;
+ else if (tag == Tag_nodefaults)
+ return 5;
else if (tag == 4 || tag == 5)
return 2;
else if (tag < 32)
@@ -8671,11 +8673,10 @@ elf32_arm_merge_eabi_attributes (bfd *ib
break;
case Tag_nodefaults:
- /* This tag is set if it exists, but the value is unused.
- Unfortunately, we don't record whether each attribute is zero
- initialized, or read from the file, so the information has been
- lost. In any case, we don't write attributes with zero values.
- Do nothing. */
+ /* This tag is set if it exists, but the value is unused (and is
+ typically zero). We don't actually need to do anything here -
+ the merge happens automatically when the type flags are merged
+ below. */
break;
case Tag_also_compatible_with:
/* Already done in Tag_CPU_arch. */
Index: gas/read.c
===================================================================
--- gas/read.c.orig
+++ gas/read.c
@@ -2123,7 +2123,7 @@ s_vendor_attribute (int vendor)
}
i = exp.X_add_number;
}
- if (type == 3
+ if ((type & 3) == 3
&& skip_past_comma (&input_line_pointer) == -1)
{
as_bad (_("expected comma"));
@@ -2140,7 +2140,7 @@ s_vendor_attribute (int vendor)
s = demand_copy_C_string (&len);
}
- switch (type)
+ switch (type & 3)
{
case 3:
bfd_elf_add_obj_attr_int_string (stdoutput, vendor, tag, i, s);