-@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 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
@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 MIPS V, MIPS32, MIPS32 Release 2,
-MIPS64, and MIPS64 Release 2 ISA processors, respectively. You can also
-switch instruction sets during the assembly; see @ref{MIPS ISA,
+@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
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.
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,
@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 ISA level, from that point on in the
assembly. @code{.set mips@var{n}} affects not only which instructions
@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}
@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
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