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Re: [PATCH] Record whether an object attribute is actually set
- From: Richard Sandiford <rdsandiford at googlemail dot com>
- To: Matthew Fortune <Matthew dot Fortune at imgtec dot com>
- Cc: "binutils\ at sourceware dot org" <binutils at sourceware dot org>
- Date: Sat, 17 May 2014 11:09:41 +0100
- Subject: Re: [PATCH] Record whether an object attribute is actually set
- Authentication-results: sourceware.org; auth=none
- References: <6D39441BF12EF246A7ABCE6654B0235352C2DA at LEMAIL01 dot le dot imgtec dot org> <20140516082705 dot GV5162 at bubble dot grove dot modra dot org>
Sorry the slow reply to this.
Alan Modra <amodra@gmail.com> writes:
> On Mon, May 12, 2014 at 11:22:13PM +0000, Matthew Fortune wrote:
>> --- a/bfd/elf-bfd.h
>> +++ b/bfd/elf-bfd.h
>> @@ -1472,6 +1472,7 @@ typedef struct obj_attribute
>> int type;
>> unsigned int i;
>> char *s;
>> + bfd_boolean is_set;
>> } obj_attribute;
>
> Note that, because someone added a 2 * 71 array of this struct to
> elf_obj_data, all ELF object BFDs get hit by any increase here,
> whether the files use attributes or not. Can you do without the flag,
> somehow?
Yeah, I was more thinking about having a flag in the assembler,
since I think we want to know whether the attribute has been set
by an explicit .gnu_attribute in the code, rather than through
some implicit setting.
How about the attached look?
Thanks,
Richard
gas/
* config/obj-elf.h (obj_elf_seen_attribute): Declare.
* config/obj-elf.c (recorded_attribute_info): New structure.
(recorded_attributes): New variable.
(record_attribute, obj_elf_seen_attribute): New functions.
(obj_elf_vendor_attribute): Record which attributes have been seen.
Index: gas/config/obj-elf.c
===================================================================
--- gas/config/obj-elf.c 2014-05-17 10:53:29.930903308 +0100
+++ gas/config/obj-elf.c 2014-05-17 11:04:20.847054304 +0100
@@ -1458,6 +1458,62 @@ skip_past_char (char ** str, char c)
}
#define skip_past_comma(str) skip_past_char (str, ',')
+/* A list of attributes that have been explicitly set by the assembly code.
+ VENDOR is the vendor id, BASE is the tag shifted right by the number
+ of bits in MASK, and bit N of MASK is set if tag BASE+N has been set. */
+struct recorded_attribute_info {
+ struct recorded_attribute_info *next;
+ int vendor;
+ unsigned int base;
+ unsigned long mask;
+};
+static struct recorded_attribute_info *recorded_attributes;
+
+/* Record that we have seen an explicit specification of attribute TAG
+ for vendor VENDOR. */
+
+static void
+record_attribute (int vendor, unsigned int tag)
+{
+ unsigned int base;
+ unsigned long mask;
+ struct recorded_attribute_info *rai;
+
+ base = tag / (8 * sizeof (rai->mask));
+ mask = 1UL << (tag % (8 * sizeof (rai->mask)));
+ for (rai = recorded_attributes; rai; rai = rai->next)
+ if (rai->vendor == vendor && rai->base == base)
+ {
+ rai->mask |= mask;
+ return;
+ }
+
+ rai = XNEW (struct recorded_attribute_info);
+ rai->next = recorded_attributes;
+ rai->vendor = vendor;
+ rai->base = base;
+ rai->mask = mask;
+ recorded_attributes = rai;
+}
+
+/* Return true if we have seen an explicit specification of attribute TAG
+ for vendor VENDOR. */
+
+bfd_boolean
+obj_elf_seen_attribute (int vendor, unsigned int tag)
+{
+ unsigned int base;
+ unsigned long mask;
+ struct recorded_attribute_info *rai;
+
+ base = tag / (8 * sizeof (rai->mask));
+ mask = 1UL << (tag % (8 * sizeof (rai->mask)));
+ for (rai = recorded_attributes; rai; rai = rai->next)
+ if (rai->vendor == vendor && rai->base == base)
+ return (rai->mask & mask) != 0;
+ return FALSE;
+}
+
/* Parse an attribute directive for VENDOR.
Returns the attribute number read, or zero on error. */
@@ -1540,6 +1596,7 @@ #define CONVERT_SYMBOLIC_ATTRIBUTE(a) -1
s = demand_copy_C_string (&len);
}
+ record_attribute (vendor, tag);
switch (type & 3)
{
case 3:
Index: gas/config/obj-elf.h
===================================================================
--- gas/config/obj-elf.h 2014-05-17 10:53:29.942903421 +0100
+++ gas/config/obj-elf.h 2014-05-17 10:53:30.553909216 +0100
@@ -165,6 +165,8 @@ extern void obj_elf_text (int);
(const char *, int, bfd_vma, int, const char *, int, int);
extern struct fix *obj_elf_vtable_inherit (int);
extern struct fix *obj_elf_vtable_entry (int);
+extern bfd_boolean obj_elf_seen_attribute
+ (int, unsigned int);
extern int obj_elf_vendor_attribute (int);
/* BFD wants to write the udata field, which is a no-no for the