* Symbols:: Symbols
* Expressions:: Expressions
* Pseudo Ops:: Assembler Directives
+@ifset ELF
+* Object Attributes:: Object Attributes
+@end ifset
* Machine Dependencies:: Machine Dependent Features
* Reporting Bugs:: Reporting Bugs
* Acknowledgements:: Who Did What
@smallexample
@c man begin SYNOPSIS
@value{AS} [@b{-a}[@b{cdhlns}][=@var{file}]] [@b{--alternate}] [@b{-D}]
+ [@b{--debug-prefix-map} @var{old}=@var{new}]
[@b{--defsym} @var{sym}=@var{val}] [@b{-f}] [@b{-g}] [@b{--gstabs}]
[@b{--gstabs+}] [@b{--gdwarf-2}] [@b{--help}] [@b{-I} @var{dir}] [@b{-J}]
[@b{-K}] [@b{-L}] [@b{--listing-lhs-width}=@var{NUM}]
Ignored. This option is accepted for script compatibility with calls to
other assemblers.
+@item --debug-prefix-map @var{old}=@var{new}
+When assembling files in directory @file{@var{old}}, record debugging
+information describing them as in @file{@var{new}} instead.
+
@item --defsym @var{sym}=@var{value}
Define the symbol @var{sym} to be @var{value} before assembling the input file.
@var{value} must be an integer constant. As in C, a leading @samp{0x}
The default is @option{--transform};
@option{--no-transform} should be used only in the rare cases when the
instructions must be exactly as specified in the assembly source.
+
+@item --rename-section @var{oldname}=@var{newname}
+When generating output sections, rename the @var{oldname} section to
+@var{newname}.
@end table
@end ifset
@menu
* Abort:: @code{.abort}
@ifset COFF
-* ABORT (COFF):: @code{.ABORT}
+* ABORT (COFF):: @code{.ABORT}
@end ifset
* Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
* Func:: @code{.func}
* Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
@ifset ELF
+* Gnu_attribute:: @code{.gnu_attribute @var{tag},@var{value}}
* Hidden:: @code{.hidden @var{names}}
@end ifset
* Scl:: @code{.scl @var{class}}
@end ifset
@ifset COFF-ELF
-* Section:: @code{.section @var{name}}
+* Section:: @code{.section @var{name}[, @var{flags}]}
@end ifset
* Set:: @code{.set @var{symbol}, @var{expression}}
* Stab:: @code{.stabd, .stabn, .stabs}
@end ifset
-* String:: @code{.string "@var{str}"}
+* String:: @code{.string "@var{str}"}, @code{.string8 "@var{str}"}, @code{.string16 "@var{str}"}, @code{.string32 "@var{str}"}, @code{.string64 "@var{str}"}
* Struct:: @code{.struct @var{expression}}
@ifset ELF
* SubSection:: @code{.subsection}
@end table
-@section @code{.loc_mark_blocks @var{enable}}
-@cindex @code{loc_mark_blocks} directive
-The @code{.loc_mark_blocks} directive makes the assembler emit an entry
+@section @code{.loc_mark_labels @var{enable}}
+@cindex @code{loc_mark_labels} directive
+The @code{.loc_mark_labels} directive makes the assembler emit an entry
to the @code{.debug_line} line number matrix with the @code{basic_block}
register in the state machine set whenever a code label is seen.
The @var{enable} argument should be either 1 or 0, to enable or disable
@end ifset
@ifset ELF
+@node Gnu_attribute
+@section @code{.gnu_attribute @var{tag},@var{value}}
+Record a @sc{gnu} object attribute for this file. @xref{Object Attributes}.
+
@node Hidden
@section @code{.hidden @var{names}}
(@pxref{PopSection}).
This directive swaps the current section (and subsection) with most recently
-referenced section (and subsection) prior to this one. Multiple
+referenced section/subsection pair prior to this one. Multiple
@code{.previous} directives in a row will flip between two sections (and their
-subsections).
+subsections). For example:
+
+@smallexample
+.section A
+ .subsection 1
+ .word 0x1234
+ .subsection 2
+ .word 0x5678
+.previous
+ .word 0x9abc
+@end smallexample
+
+Will place 0x1234 and 0x9abc into subsection 1 and 0x5678 into subsection 2 of
+section A. Whilst:
+
+@smallexample
+.section A
+.subsection 1
+ # Now in section A subsection 1
+ .word 0x1234
+.section B
+.subsection 0
+ # Now in section B subsection 0
+ .word 0x5678
+.subsection 1
+ # Now in section B subsection 1
+ .word 0x9abc
+.previous
+ # Now in section B subsection 0
+ .word 0xdef0
+@end smallexample
+
+Will place 0x1234 into section A, 0x5678 and 0xdef0 into subsection 0 of
+section B and 0x9abc into subsection 1 of section B.
In terms of the section stack, this directive swaps the current section with
the top section on the section stack.
@c end have-stabs
@node String
-@section @code{.string} "@var{str}"
+@section @code{.string} "@var{str}", @code{.string8} "@var{str}", @code{.string16}
+"@var{str}", @code{.string32} "@var{str}", @code{.string64} "@var{str}"
@cindex string, copying to object file
+@cindex string8, copying to object file
+@cindex string16, copying to object file
+@cindex string32, copying to object file
+@cindex string64, copying to object file
@cindex @code{string} directive
+@cindex @code{string8} directive
+@cindex @code{string16} directive
+@cindex @code{string32} directive
+@cindex @code{string64} directive
Copy the characters in @var{str} to the object file. You may specify more than
one string to copy, separated by commas. Unless otherwise specified for a
particular machine, the assembler marks the end of each string with a 0 byte.
You can use any of the escape sequences described in @ref{Strings,,Strings}.
+The variants @code{string16}, @code{string32} and @code{string64} differ from
+the @code{string} pseudo opcode in that each 8-bit character from @var{str} is
+copied and expanded to 16, 32 or 64 bits respectively. The expanded characters
+are stored in target endianness byte order.
+
+Example:
+@smallexample
+ .string32 "BYE"
+expands to:
+ .string "B\0\0\0Y\0\0\0E\0\0\0" /* On little endian targets. */
+ .string "\0\0\0B\0\0\0Y\0\0\0E" /* On big endian targets. */
+@end smallexample
+
+
@node Struct
@section @code{.struct @var{expression}}
The syntaxes supported are:
@smallexample
- .type <name> STT_FUNCTION
- .type <name> STT_OBJECT
+ .type <name> STT_<TYPE_IN_UPPER_CASE>
+ .type <name>,#<type>
+ .type <name>,@@<type>
+ .type <name>,%>type>
+ .type <name>,"<type>"
+@end smallexample
- .type <name>,#function
- .type <name>,#object
+The types supported are:
- .type <name>,@@function
- .type <name>,@@object
+@table @gcctabopt
+@item STT_FUNC
+@itemx function
+Mark the symbol as being a function name.
+
+@item STT_OBJECT
+@itemx object
+Mark the symbol as being a data object.
+
+@item STT_TLS
+@itemx tls_object
+Mark the symbol as being a thead-local data object.
+
+@item STT_COMMON
+@itemx common
+Mark the symbol as being a common data object.
+@end table
+
+Note: Some targets support extra types in addition to those listed above.
- .type <name>,%function
- .type <name>,%object
-
- .type <name>,"function"
- .type <name>,"object"
-@end smallexample
@end ifset
@end ifset
@item .line
@end table
+@ifset ELF
+@node Object Attributes
+@chapter Object Attributes
+@cindex object attributes
+
+@command{@value{AS}} assembles source files written for a specific architecture
+into object files for that architecture. But not all object files are alike.
+Many architectures support incompatible variations. For instance, floating
+point arguments might be passed in floating point registers if the object file
+requires hardware floating point support---or floating point arguments might be
+passed in integer registers if the object file supports processors with no
+hardware floating point unit. Or, if two objects are built for different
+generations of the same architecture, the combination may require the
+newer generation at run-time.
+
+This information is useful during and after linking. At link time,
+@command{@value{LD}} can warn about incompatible object files. After link
+time, tools like @command{gdb} can use it to process the linked file
+correctly.
+
+Compatibility information is recorded as a series of object attributes. Each
+attribute has a @dfn{vendor}, @dfn{tag}, and @dfn{value}. The vendor is a
+string, and indicates who sets the meaning of the tag. The tag is an integer,
+and indicates what property the attribute describes. The value may be a string
+or an integer, and indicates how the property affects this object. Missing
+attributes are the same as attributes with a zero value or empty string value.
+
+Object attributes were developed as part of the ABI for the ARM Architecture.
+The file format is documented in @cite{ELF for the ARM Architecture}.
+
+@menu
+* GNU Object Attributes:: @sc{gnu} Object Attributes
+* Defining New Object Attributes:: Defining New Object Attributes
+@end menu
+
+@node GNU Object Attributes
+@section @sc{gnu} Object Attributes
+
+The @code{.gnu_attribute} directive records an object attribute
+with vendor @samp{gnu}.
+
+Except for @samp{Tag_compatibility}, which has both an integer and a string for
+its value, @sc{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 (@code{@var{tag} &
+2} is set for architecture-independent attributes and clear for
+architecture-dependent ones.
+
+@subsection Common @sc{gnu} attributes
+
+These attributes are valid on all architectures.
+
+@table @r
+@item 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.
+@end table
+
+@subsection MIPS Attributes
+
+@table @r
+@item Tag_GNU_MIPS_ABI_FP (4)
+The floating-point ABI used by this object file. The value will be:
+
+@itemize @bullet
+@item
+0 for files not affected by the floating-point ABI.
+@item
+1 for files using the hardware floating-point with a standard double-precision
+FPU.
+@item
+2 for files using the hardware floating-point ABI with a single-precision FPU.
+@item
+3 for files using the software floating-point ABI.
+@end itemize
+@end table
+
+@subsection PowerPC Attributes
+
+@table @r
+@item Tag_GNU_Power_ABI_FP (4)
+The floating-point ABI used by this object file. The value will be:
+
+@itemize @bullet
+@item
+0 for files not affected by the floating-point ABI.
+@item
+1 for files using the hardware floating-point ABI.
+@item
+2 for files using the software floating-point ABI.
+@end itemize
+
+@item Tag_GNU_Power_ABI_Vector (8)
+The vector ABI used by this object file. The value will be:
+
+@itemize @bullet
+@item
+0 for files not affected by the vector ABI.
+@item
+1 for files using general purpose registers to pass vectors.
+@item
+2 for files using AltiVec registers to pass vectors.
+@item
+3 for files using SPE registers to pass vectors.
+@end itemize
+@end table
+
+@node Defining New Object Attributes
+@section Defining New Object Attributes
+
+If you want to define a new @sc{gnu} object attribute, here are the places you
+will need to modify. New attributes should be discussed on the @samp{binutils}
+mailing list.
+
+@itemize @bullet
+@item
+This manual, which is the official register of attributes.
+@item
+The header for your architecture @file{include/elf}, to define the tag.
+@item
+The @file{bfd} support file for your architecture, to merge the attribute
+and issue any appropriate link warnings.
+@item
+Test cases in @file{ld/testsuite} for merging and link warnings.
+@item
+@file{binutils/readelf.c} to display your attribute.
+@item
+GCC, if you want the compiler to mark the attribute automatically.
+@end itemize
+
+@end ifset
+
@ifset GENERIC
@node Machine Dependencies
@chapter Machine Dependent Features
@ifset BFIN
* BFIN-Dependent:: BFIN Dependent Features
@end ifset
+@ifset CR16
+* CR16-Dependent:: CR16 Dependent Features
+@end ifset
@ifset CRIS
* CRIS-Dependent:: CRIS Dependent Features
@end ifset
@include c-bfin.texi
@end ifset
+@ifset CR16
+@include c-cr16.texi
+@end ifset
+
@ifset CRIS
@include c-cris.texi
@end ifset
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