-@c Copyright 1991, 1992, 1993, 1994, 1995, 1997, 1999, 2000, 2001,
-@c 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2013
-@c Free Software Foundation, Inc.
+@c Copyright (C) 1991-2014 Free Software Foundation, Inc.
@c This is part of the GAS manual.
@c For copying conditions, see the file as.texinfo.
@ifset GENERIC
* MIPS Symbol Sizes:: Directives to override the size of symbols
* MIPS Small Data:: Controlling the use of small data accesses
* MIPS ISA:: Directives to override the ISA level
+* MIPS assembly options:: Directives to control code generation
* MIPS autoextend:: Directives for extending MIPS 16 bit instructions
* MIPS insn:: Directive to mark data as an instruction
+* MIPS FP ABIs:: Marking which FP ABI is in use
+* MIPS NaN Encodings:: Directives to record which NaN encoding is being used
* MIPS Option Stack:: Directives to save and restore options
* MIPS ASE Instruction Generation Overrides:: Directives to control
generation of MIPS ASE instructions
@itemx -mips5
@itemx -mips32
@itemx -mips32r2
+@itemx -mips32r3
+@itemx -mips32r5
@itemx -mips64
@itemx -mips64r2
+@itemx -mips64r3
+@itemx -mips64r5
Generate code for a particular MIPS Instruction Set Architecture level.
@samp{-mips1} corresponds to the R2000 and R3000 processors,
@samp{-mips2} to the R6000 processor, @samp{-mips3} to the
-R4000 processor, and @samp{-mips4} to the R8000 and
-R10000 processors. @samp{-mips5}, @samp{-mips32}, @samp{-mips32r2},
-@samp{-mips64}, and @samp{-mips64r2}
-correspond to generic
-@sc{MIPS V}, @sc{MIPS32}, @sc{MIPS32 Release 2}, @sc{MIPS64},
-and @sc{MIPS64 Release 2}
-ISA processors, respectively. You can also switch
-instruction sets during the assembly; see @ref{MIPS ISA, Directives to
-override the ISA level}.
+R4000 processor, and @samp{-mips4} to the R8000 and R10000 processors.
+@samp{-mips5}, @samp{-mips32}, @samp{-mips32r2}, @samp{-mips32r3},
+@samp{-mips32r5}, @samp{-mips64}, @samp{-mips64r2}, @samp{-mips64r3}, and
+@samp{-mips64r5} correspond to generic MIPS V, MIPS32, MIPS32 Release 2,
+MIPS32 Release 3, MIPS32 Release 5, MIPS64, and MIPS64 Release 2,
+MIPS64 Release 3, and MIPS64 Release 5 ISA processors, respectively. You
+can also switch instruction sets during the assembly; see @ref{MIPS ISA,
+Directives to override the ISA level}.
@item -mgp32
@itemx -mfp32
of registers to be changed for parts of an object. The default value is
restored by @code{.set gp=default} and @code{.set fp=default}.
+@item -mfpxx
+Make no assumptions about whether 32-bit or 64-bit floating-point
+registers are available. This is provided to support having modules
+compatible with either @samp{-mfp32} or @samp{-mfp64}. This option can
+only be used with MIPS II and above.
+
+The @code{.set fp=xx} directive allows a part of an object to be marked
+as not making assumptions about 32-bit or 64-bit FP registers. The
+default value is restored by @code{.set fp=default}.
+
+@item -modd-spreg
+@itemx -mno-odd-spreg
+Enable use of floating-point operations on odd-numbered single-precision
+registers when supported by the ISA. @samp{-mfpxx} implies
+@samp{-mno-odd-spreg}, otherwise the default is @samp{-modd-spreg}
+
@item -mips16
@itemx -no-mips16
Generate code for the MIPS 16 processor. This is equivalent to putting
This tells the assembler to accept MCU instructions.
@samp{-mno-mcu} turns off this option.
+@item -mmsa
+@itemx -mno-msa
+Generate code for the MIPS SIMD Architecture Extension.
+This tells the assembler to accept MSA instructions.
+@samp{-mno-msa} turns off this option.
+
+@item -mxpa
+@itemx -mno-xpa
+Generate code for the MIPS eXtended Physical Address (XPA) Extension.
+This tells the assembler to accept XPA instructions.
+@samp{-mno-xpa} turns off this option.
+
@item -mvirt
@itemx -mno-virt
Generate code for the Virtualization Application Specific Extension.
This tells the assembler to accept Virtualization instructions.
@samp{-mno-virt} turns off this option.
+@item -minsn32
+@itemx -mno-insn32
+Only use 32-bit instruction encodings when generating code for the
+microMIPS processor. This option inhibits the use of any 16-bit
+instructions. This is equivalent to putting @code{.set insn32} at
+the start of the assembly file. @samp{-mno-insn32} turns off this
+option. This is equivalent to putting @code{.set noinsn32} at the
+start of the assembly file. By default @samp{-mno-insn32} is
+selected, allowing all instructions to be used.
+
@item -mfix7000
@itemx -mno-fix7000
Cause nops to be inserted if the read of the destination register
of an mfhi or mflo instruction occurs in the following two instructions.
+@item -mfix-rm7000
+@itemx -mno-fix-rm7000
+Cause nops to be inserted if a dmult or dmultu instruction is
+followed by a load instruction.
+
@item -mfix-loongson2f-jump
@itemx -mno-fix-loongson2f-jump
Eliminate instruction fetch from outside 256M region to work around the
1004kf2_1,
1004kf,
1004kf1_1,
+p5600,
5kc,
5kf,
20kc,
however this has not been implemented and if their target turns out of
reach, they produce an error even if branch relaxation is enabled.
-Also no @sc{mips16} branches are ever relaxed.
+Also no MIPS16 branches are ever relaxed.
By default @samp{--no-relax-branch} is selected, causing any out-of-range
branches to produce an error.
+@cindex @option{-mnan=} command line option, MIPS
+@item -mnan=@var{encoding}
+This option indicates whether the source code uses the IEEE 2008
+NaN encoding (@option{-mnan=2008}) or the original MIPS encoding
+(@option{-mnan=legacy}). It is equivalent to adding a @code{.nan}
+directive to the beginning of the source file. @xref{MIPS NaN Encodings}.
+
+@option{-mnan=legacy} is the default if no @option{-mnan} option or
+@code{.nan} directive is used.
+
@item --trap
@itemx --no-break
@c FIXME! (1) reflect these options (next item too) in option summaries;
@kindex @code{.set mips@var{n}}
@sc{gnu} @code{@value{AS}} supports an additional directive to change
the MIPS Instruction Set Architecture level on the fly: @code{.set
-mips@var{n}}. @var{n} should be a number from 0 to 5, or 32, 32r2, 64
-or 64r2.
+mips@var{n}}. @var{n} should be a number from 0 to 5, or 32, 32r2, 32r3,
+32r5, 64, 64r2, 64r3 or 64r5.
The values other than 0 make the assembler accept instructions
-for the corresponding @sc{isa} level, from that point on in the
+for the corresponding ISA level, from that point on in the
assembly. @code{.set mips@var{n}} affects not only which instructions
are permitted, but also how certain macros are expanded. @code{.set
-mips0} restores the @sc{isa} level to its original level: either the
+mips0} restores the ISA level to its original level: either the
level you selected with command line options, or the default for your
-configuration. You can use this feature to permit specific @sc{mips3}
+configuration. You can use this feature to permit specific MIPS III
instructions while assembling in 32 bit mode. Use this directive with
care!
Traditional MIPS assemblers do not support this directive.
+@node MIPS assembly options
+@section Directives to control code generation
+
+@cindex MIPS directives to override command line options
+@kindex @code{.module}
+The @code{.module} directive allows command line options to be set directly
+from assembly. The format of the directive matches the @code{.set}
+directive but only those options which are relevant to a whole module are
+supported. The effect of a @code{.module} directive is the same as the
+corresponding command line option. Where @code{.set} directives support
+returning to a default then the @code{.module} directives do not as they
+define the defaults.
+
+These module-level directives must appear first in assembly.
+
+Traditional MIPS assemblers do not support this directive.
+
+@cindex MIPS 32-bit microMIPS instruction generation override
+@kindex @code{.set insn32}
+@kindex @code{.set noinsn32}
+The directive @code{.set insn32} makes the assembler only use 32-bit
+instruction encodings when generating code for the microMIPS processor.
+This directive inhibits the use of any 16-bit instructions from that
+point on in the assembly. The @code{.set noinsn32} directive allows
+16-bit instructions to be accepted.
+
+Traditional MIPS assemblers do not support this directive.
+
@node MIPS autoextend
@section Directives for extending MIPS 16 bit instructions
@end example
+@node MIPS FP ABIs
+@section Directives to control the FP ABI
+@menu
+* MIPS FP ABI History:: History of FP ABIs
+* MIPS FP ABI Variants:: Supported FP ABIs
+* MIPS FP ABI Selection:: Automatic selection of FP ABI
+* MIPS FP ABI Compatibility:: Linking different FP ABI variants
+@end menu
+
+@node MIPS FP ABI History
+@subsection History of FP ABIs
+@cindex @code{.gnu_attribute 4, @var{n}} directive, MIPS
+@cindex @code{.gnu_attribute Tag_GNU_MIPS_ABI_FP, @var{n}} directive, MIPS
+The MIPS ABIs support a variety of different floating-point extensions
+where calling-convention and register sizes vary for floating-point data.
+The extensions exist to support a wide variety of optional architecture
+features. The resulting ABI variants are generally incompatible with each
+other and must be tracked carefully.
+
+Traditionally the use of an explicit @code{.gnu_attribute 4, @var{n}}
+directive is used to indicate which ABI is in use by a specific module.
+It was then left to the user to ensure that command line options and the
+selected ABI were compatible with some potential for inconsistencies.
+
+@node MIPS FP ABI Variants
+@subsection Supported FP ABIs
+The supported floating-point ABI variants are:
+
+@table @code
+@item 0 - No floating-point
+This variant is used to indicate that floating-point is not used within
+the module at all and therefore has no impact on the ABI. This is the
+default.
+
+@item 1 - Double-precision
+This variant indicates that double-precision support is used. For 64-bit
+ABIs this means that 64-bit wide floating-point registers are required.
+For 32-bit ABIs this means that 32-bit wide floating-point registers are
+required and double-precision operations use pairs of registers.
+
+@item 2 - Single-precision
+This variant indicates that single-precision support is used. Double
+precision operations will be supported via soft-float routines.
+
+@item 3 - Soft-float
+This variant indicates that although floating-point support is used all
+operations are emulated in software. This means the ABI is modified to
+pass all floating-point data in general-purpose registers.
+
+@item 4 - Deprecated
+This variant existed as an initial attempt at supporting 64-bit wide
+floating-point registers for O32 ABI on a MIPS32r2 cpu. This has been
+superceded by @value{5}, @value{6} and @value{7}.
+
+@item 5 - Double-precision 32-bit CPU, 32-bit or 64-bit FPU
+This variant is used by 32-bit ABIs to indicate that the floating-point
+code in the module has been designed to operate correctly with either
+32-bit wide or 64-bit wide floating-point registers. Double-precision
+support is used. Only O32 currently supports this variant and requires
+a minimum architecture of MIPS II.
+
+@item 6 - Double-precision 32-bit FPU, 64-bit FPU
+This variant is used by 32-bit ABIs to indicate that the floating-point
+code in the module requires 64-bit wide floating-point registers.
+Double-precision support is used. Only O32 currently supports this
+variant and requires a minimum architecture of MIPS32r2.
+
+@item 7 - Double-precision compat 32-bit FPU, 64-bit FPU
+This variant is used by 32-bit ABIs to indicate that the floating-point
+code in the module requires 64-bit wide floating-point registers.
+Double-precision support is used. This differs from the previous ABI
+as it restricts use of odd-numbered single-precision registers. Only
+O32 currently supports this variant and requires a minimum architecture
+of MIPS32r2.
+@end table
+
+@node MIPS FP ABI Selection
+@subsection Automatic selection of FP ABI
+@cindex @code{.module fp=@var{nn}} directive, MIPS
+In order to simplify and add safety to the process of selecting the
+correct floating-point ABI, the assembler will automatically infer the
+correct @code{.gnu_attribute 4, @var{n}} directive based on command line
+options and @code{.module} overrides. Where an explicit
+@code{.gnu_attribute 4, @var{n}} directive has been seen then a warning
+will be raised if it does not match an inferred setting.
+
+The floating-point ABI is inferred as follows. If @samp{-msoft-float}
+has been used the module will be marked as soft-float. If
+@samp{-msingle-float} has been used then the module will be marked as
+single-precision. The remaining ABIs are then selected based
+on the FP register width. Double-precision is selected if the width
+of GP and FP registers match and the special double-precision variants
+for 32-bit ABIs are then selected depending on @samp{-mfpxx},
+@samp{-mfp64} and @samp{-mno-odd-spreg}.
+
+@node MIPS FP ABI Compatibility
+@subsection Linking different FP ABI variants
+Modules using the default FP ABI (no floating-point) can be linked with
+any other (singular) FP ABI variant.
+
+Special compatibility support exists for O32 with the four
+double-precision FP ABI variants. The @samp{-mfpxx} FP ABI is specifically
+designed to be compatible with the standard double-precision ABI and the
+@samp{-mfp64} FP ABIs. This makes it desirable for O32 modules to be
+built as @samp{-mfpxx} to ensure the maximum compatibility with other
+modules produced for more specific needs. The only FP ABIs which cannot
+be linked together are the standard double-precision ABI and the full
+@samp{-mfp64} ABI with @samp{-modd-spreg}.
+
+@node MIPS NaN Encodings
+@section Directives to record which NaN encoding is being used
+
+@cindex MIPS IEEE 754 NaN data encoding selection
+@cindex @code{.nan} directive, MIPS
+The IEEE 754 floating-point standard defines two types of not-a-number
+(NaN) data: ``signalling'' NaNs and ``quiet'' NaNs. The original version
+of the standard did not specify how these two types should be
+distinguished. Most implementations followed the i387 model, in which
+the first bit of the significand is set for quiet NaNs and clear for
+signalling NaNs. However, the original MIPS implementation assigned the
+opposite meaning to the bit, so that it was set for signalling NaNs and
+clear for quiet NaNs.
+
+The 2008 revision of the standard formally suggested the i387 choice
+and as from Sep 2012 the current release of the MIPS architecture
+therefore optionally supports that form. Code that uses one NaN encoding
+would usually be incompatible with code that uses the other NaN encoding,
+so MIPS ELF objects have a flag (@code{EF_MIPS_NAN2008}) to record which
+encoding is being used.
+
+Assembly files can use the @code{.nan} directive to select between the
+two encodings. @samp{.nan 2008} says that the assembly file uses the
+IEEE 754-2008 encoding while @samp{.nan legacy} says that the file uses
+the original MIPS encoding. If several @code{.nan} directives are given,
+the final setting is the one that is used.
+
+The command-line options @option{-mnan=legacy} and @option{-mnan=2008}
+can be used instead of @samp{.nan legacy} and @samp{.nan 2008}
+respectively. However, any @code{.nan} directive overrides the
+command-line setting.
+
+@samp{.nan legacy} is the default if no @code{.nan} directive or
+@option{-mnan} option is given.
+
+Note that @sc{gnu} @code{@value{AS}} does not produce NaNs itself and
+therefore these directives do not affect code generation. They simply
+control the setting of the @code{EF_MIPS_NAN2008} flag.
+
+Traditional MIPS assemblers do not support these directives.
+
@node MIPS Option Stack
@section Directives to save and restore options
@kindex @code{.set nosmartmips}
The directive @code{.set smartmips} makes the assembler accept
instructions from the SmartMIPS Application Specific Extension to the
-MIPS32 @sc{isa} from that point on in the assembly. The
+MIPS32 ISA from that point on in the assembly. The
@code{.set nosmartmips} directive prevents SmartMIPS instructions from
being accepted.
in the assembly. The @code{.set nomcu} directive prevents MCU
instructions from being accepted.
+@cindex MIPS SIMD Architecture instruction generation override
+@kindex @code{.set msa}
+@kindex @code{.set nomsa}
+The directive @code{.set msa} makes the assembler accept instructions
+from the MIPS SIMD Architecture Extension from that point on
+in the assembly. The @code{.set nomsa} directive prevents MSA
+instructions from being accepted.
+
@cindex Virtualization instruction generation override
@kindex @code{.set virt}
@kindex @code{.set novirt}
on in the assembly. The @code{.set novirt} directive prevents Virtualization
instructions from being accepted.
+@cindex MIPS eXtended Physical Address (XPA) instruction generation override
+@kindex @code{.set xpa}
+@kindex @code{.set noxpa}
+The directive @code{.set xpa} makes the assembler accept instructions
+from the XPA Extension from that point on in the assembly. The
+@code{.set noxpa} directive prevents XPA instructions from being accepted.
+
Traditional MIPS assemblers do not support these directives.
@node MIPS Floating-Point
projects / external / binutils.git / blobdiff