as: GNU Object Attributes
8.1 GNU Object Attributes
=========================
The '.gnu_attribute' directive records an object attribute with vendor
'gnu'.
Except for 'Tag_compatibility', which has both an integer and a
string for its value, GNU attributes have a string value if the tag
number is odd and an integer value if the tag number is even. The
second bit ('TAG & 2' is set for architecture-independent attributes and
clear for architecture-dependent ones.
8.1.1 Common GNU attributes
---------------------------
These attributes are valid on all architectures.
Tag_compatibility (32)
The compatibility attribute takes an integer flag value and a
vendor name. If the flag value is 0, the file is compatible with
other toolchains. If it is 1, then the file is only compatible
with the named toolchain. If it is greater than 1, the file can
only be processed by other toolchains under some private
arrangement indicated by the flag value and the vendor name.
8.1.2 MIPS Attributes
---------------------
Tag_GNU_MIPS_ABI_FP (4)
The floating-point ABI used by this object file. The value will
be:
* 0 for files not affected by the floating-point ABI.
* 1 for files using the hardware floating-point ABI with a
standard double-precision FPU.
* 2 for files using the hardware floating-point ABI with a
single-precision FPU.
* 3 for files using the software floating-point ABI.
* 4 for files using the deprecated hardware floating-point ABI
which used 64-bit floating-point registers, 32-bit
general-purpose registers and increased the number of
callee-saved floating-point registers.
* 5 for files using the hardware floating-point ABI with a
double-precision FPU with either 32-bit or 64-bit
floating-point registers and 32-bit general-purpose registers.
* 6 for files using the hardware floating-point ABI with 64-bit
floating-point registers and 32-bit general-purpose registers.
* 7 for files using the hardware floating-point ABI with 64-bit
floating-point registers, 32-bit general-purpose registers and
a rule that forbids the direct use of odd-numbered
single-precision floating-point registers.
8.1.3 PowerPC Attributes
------------------------
Tag_GNU_Power_ABI_FP (4)
The floating-point ABI used by this object file. The value will
be:
* 0 for files not affected by the floating-point ABI.
* 1 for files using double-precision hardware floating-point
ABI.
* 2 for files using the software floating-point ABI.
* 3 for files using single-precision hardware floating-point
ABI.
Tag_GNU_Power_ABI_Vector (8)
The vector ABI used by this object file. The value will be:
* 0 for files not affected by the vector ABI.
* 1 for files using general purpose registers to pass vectors.
* 2 for files using AltiVec registers to pass vectors.
* 3 for files using SPE registers to pass vectors.
8.1.4 IBM z Systems Attributes
------------------------------
Tag_GNU_S390_ABI_Vector (8)
The vector ABI used by this object file. The value will be:
* 0 for files not affected by the vector ABI.
* 1 for files using software vector ABI.
* 2 for files using hardware vector ABI.
Info Catalog
as: Object Attributes
as: Defining New Object Attributes