@c Copyright 1991, 1992, 1993, 1994, 1995, 1997, 1998, 1999, 2000,
-@c 2001, 2003, 2004
+@c 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2011
@c Free Software Foundation, Inc.
@c This is part of the GAS manual.
@c For copying conditions, see the file as.texinfo.
+@c man end
+
@ifset GENERIC
@page
@node i386-Dependent
@end ifclear
@cindex i386 support
-@cindex i80306 support
+@cindex i80386 support
@cindex x86-64 support
The i386 version @code{@value{AS}} supports both the original Intel 386
@menu
* i386-Options:: Options
-* i386-Syntax:: AT&T Syntax versus Intel Syntax
+* i386-Directives:: X86 specific directives
+* i386-Syntax:: Syntactical considerations
* i386-Mnemonics:: Instruction Naming
* i386-Regs:: Register Naming
* i386-Prefixes:: Instruction Prefixes
* i386-Jumps:: Handling of Jump Instructions
* i386-Float:: Floating Point
* i386-SIMD:: Intel's MMX and AMD's 3DNow! SIMD Operations
+* i386-LWP:: AMD's Lightweight Profiling Instructions
+* i386-BMI:: Bit Manipulation Instruction
+* i386-TBM:: AMD's Trailing Bit Manipulation Instructions
* i386-16bit:: Writing 16-bit Code
* i386-Arch:: Specifying an x86 CPU architecture
* i386-Bugs:: AT&T Syntax bugs
The i386 version of @code{@value{AS}} has a few machine
dependent options:
-@table @code
+@c man begin OPTIONS
+@table @gcctabopt
@cindex @samp{--32} option, i386
@cindex @samp{--32} option, x86-64
+@cindex @samp{--x32} option, i386
+@cindex @samp{--x32} option, x86-64
@cindex @samp{--64} option, i386
@cindex @samp{--64} option, x86-64
-@item --32 | --64
-Select the word size, either 32 bits or 64 bits. Selecting 32-bit
-implies Intel i386 architecture, while 64-bit implies AMD x86-64
-architecture.
+@item --32 | --x32 | --64
+Select the word size, either 32 bits or 64 bits. @samp{--32}
+implies Intel i386 architecture, while @samp{--x32} and @samp{--64}
+imply AMD x86-64 architecture with 32-bit or 64-bit word-size
+respectively.
These options are only available with the ELF object file format, and
require that the necessary BFD support has been included (on a 32-bit
@code{nocona},
@code{core},
@code{core2},
+@code{corei7},
+@code{l1om},
@code{k6},
@code{k6_2},
@code{athlon},
@code{opteron},
@code{k8},
@code{amdfam10},
+@code{bdver1},
+@code{bdver2},
@code{generic32} and
@code{generic64}.
accept various extension mnemonics. For example,
@code{-march=i686+sse4+vmx} extends @var{i686} with @var{sse4} and
@var{vmx}. The following extensions are currently supported:
+@code{8087},
+@code{287},
+@code{387},
+@code{no87},
@code{mmx},
+@code{nommx},
@code{sse},
@code{sse2},
@code{sse3},
@code{sse4.1},
@code{sse4.2},
@code{sse4},
+@code{nosse},
@code{avx},
+@code{avx2},
+@code{noavx},
@code{vmx},
@code{smx},
@code{xsave},
+@code{xsaveopt},
@code{aes},
-@code{clmul},
+@code{pclmul},
+@code{fsgsbase},
+@code{rdrnd},
+@code{f16c},
+@code{bmi2},
@code{fma},
+@code{movbe},
+@code{ept},
+@code{lzcnt},
+@code{invpcid},
+@code{clflush},
+@code{lwp},
+@code{fma4},
+@code{xop},
+@code{syscall},
+@code{rdtscp},
@code{3dnow},
@code{3dnowa},
@code{sse4a},
@code{svme},
@code{abm} and
@code{padlock}.
+Note that rather than extending a basic instruction set, the extension
+mnemonics starting with @code{no} revoke the respective functionality.
When the @code{.arch} directive is used with @option{-march}, the
@code{.arch} directive will take precedent.
This option specifies that the assembler should encode SSE instructions
with VEX prefix.
+@cindex @samp{-msse-check=} option, i386
+@cindex @samp{-msse-check=} option, x86-64
+@item -msse-check=@var{none}
+@itemx -msse-check=@var{warning}
+@itemx -msse-check=@var{error}
+These options control if the assembler should check SSE intructions.
+@option{-msse-check=@var{none}} will make the assembler not to check SSE
+instructions, which is the default. @option{-msse-check=@var{warning}}
+will make the assembler issue a warning for any SSE intruction.
+@option{-msse-check=@var{error}} will make the assembler issue an error
+for any SSE intruction.
+
+@cindex @samp{-mavxscalar=} option, i386
+@cindex @samp{-mavxscalar=} option, x86-64
+@item -mavxscalar=@var{128}
+@itemx -mavxscalar=@var{256}
+This options control how the assembler should encode scalar AVX
+instructions. @option{-mavxscalar=@var{128}} will encode scalar
+AVX instructions with 128bit vector length, which is the default.
+@option{-mavxscalar=@var{256}} will encode scalar AVX instructions
+with 256bit vector length.
+
@cindex @samp{-mmnemonic=} option, i386
@cindex @samp{-mmnemonic=} option, x86-64
@item -mmnemonic=@var{att}
-@item -mmnemonic=@var{intel}
+@itemx -mmnemonic=@var{intel}
This option specifies instruction mnemonic for matching instructions.
The @code{.att_mnemonic} and @code{.intel_mnemonic} directives will
take precedent.
@cindex @samp{-msyntax=} option, i386
@cindex @samp{-msyntax=} option, x86-64
@item -msyntax=@var{att}
-@item -msyntax=@var{intel}
+@itemx -msyntax=@var{intel}
This option specifies instruction syntax when processing instructions.
The @code{.att_syntax} and @code{.intel_syntax} directives will
take precedent.
This opetion specifies that registers don't require a @samp{%} prefix.
The @code{.att_syntax} and @code{.intel_syntax} directives will take precedent.
+@end table
+@c man end
+
+@node i386-Directives
+@section x86 specific Directives
+
+@cindex machine directives, x86
+@cindex x86 machine directives
+@table @code
+
+@cindex @code{lcomm} directive, COFF
+@item .lcomm @var{symbol} , @var{length}[, @var{alignment}]
+Reserve @var{length} (an absolute expression) bytes for a local common
+denoted by @var{symbol}. The section and value of @var{symbol} are
+those of the new local common. The addresses are allocated in the bss
+section, so that at run-time the bytes start off zeroed. Since
+@var{symbol} is not declared global, it is normally not visible to
+@code{@value{LD}}. The optional third parameter, @var{alignment},
+specifies the desired alignment of the symbol in the bss section.
+
+This directive is only available for COFF based x86 targets.
+
+@c FIXME: Document other x86 specific directives ? Eg: .code16gcc,
+@c .largecomm
+
@end table
@node i386-Syntax
-@section AT&T Syntax versus Intel Syntax
+@section i386 Syntactical Considerations
+@menu
+* i386-Variations:: AT&T Syntax versus Intel Syntax
+* i386-Chars:: Special Characters
+@end menu
+
+@node i386-Variations
+@subsection AT&T Syntax versus Intel Syntax
@cindex i386 intel_syntax pseudo op
@cindex intel_syntax pseudo op, i386
Intel @samp{mov al, byte ptr @var{foo}} is @samp{movb @var{foo}, %al} in AT&T
syntax.
+In 64-bit code, @samp{movabs} can be used to encode the @samp{mov}
+instruction with the 64-bit displacement or immediate operand.
+
@cindex return instructions, i386
@cindex i386 jump, call, return
@cindex return instructions, x86-64
programs. Unix style systems expect all programs to be single sections.
@end itemize
+@node i386-Chars
+@subsection Special Characters
+
+@cindex line comment character, i386
+@cindex i386 line comment character
+The presence of a @samp{#} appearing anywhere on a line indicates the
+start of a comment that extends to the end of that line.
+
+If a @samp{#} appears as the first character of a line then the whole
+line is treated as a comment, but in this case the line can also be a
+logical line number directive (@pxref{Comments}) or a preprocessor
+control command (@pxref{Preprocessing}).
+
+If the @option{--divide} command line option has not been specified
+then the @samp{/} character appearing anywhere on a line also
+introduces a line comment.
+
+@cindex line separator, i386
+@cindex statement separator, i386
+@cindex i386 line separator
+The @samp{;} character can be used to separate statements on the same
+line.
+
@node i386-Mnemonics
@section Instruction Naming
@samp{wq} (from word to quadruple word), and @samp{lq} (from long to
quadruple word).
+@cindex encoding options, i386
+@cindex encoding options, x86-64
+
+Different encoding options can be specified via optional mnemonic
+suffix. @samp{.s} suffix swaps 2 register operands in encoding when
+moving from one register to another. @samp{.d32} suffix forces 32bit
+displacement in encoding.
+
@cindex conversion instructions, i386
@cindex i386 conversion instructions
@cindex conversion instructions, x86-64
See Intel and AMD documentation, keeping in mind that the operand order in
instructions is reversed from the Intel syntax.
+@node i386-LWP
+@section AMD's Lightweight Profiling Instructions
+
+@cindex LWP, i386
+@cindex LWP, x86-64
+
+@code{@value{AS}} supports AMD's Lightweight Profiling (LWP)
+instruction set, available on AMD's Family 15h (Orochi) processors.
+
+LWP enables applications to collect and manage performance data, and
+react to performance events. The collection of performance data
+requires no context switches. LWP runs in the context of a thread and
+so several counters can be used independently across multiple threads.
+LWP can be used in both 64-bit and legacy 32-bit modes.
+
+For detailed information on the LWP instruction set, see the
+@cite{AMD Lightweight Profiling Specification} available at
+@uref{http://developer.amd.com/cpu/LWP,Lightweight Profiling Specification}.
+
+@node i386-BMI
+@section Bit Manipulation Instructions
+
+@cindex BMI, i386
+@cindex BMI, x86-64
+
+@code{@value{AS}} supports the Bit Manipulation (BMI) instruction set.
+
+BMI instructions provide several instructions implementing individual
+bit manipulation operations such as isolation, masking, setting, or
+resetting.
+
+@c Need to add a specification citation here when available.
+
+@node i386-TBM
+@section AMD's Trailing Bit Manipulation Instructions
+
+@cindex TBM, i386
+@cindex TBM, x86-64
+
+@code{@value{AS}} supports AMD's Trailing Bit Manipulation (TBM)
+instruction set, available on AMD's BDVER2 processors (Trinity and
+Viperfish).
+
+TBM instructions provide instructions implementing individual bit
+manipulation operations such as isolating, masking, setting, resetting,
+complementing, and operations on trailing zeros and ones.
+
+@c Need to add a specification citation here when available.
+
@node i386-16bit
@section Writing 16-bit Code
it also supports writing code to run in real mode or in 16-bit protected
mode code segments. To do this, put a @samp{.code16} or
@samp{.code16gcc} directive before the assembly language instructions to
-be run in 16-bit mode. You can switch @code{@value{AS}} back to writing
-normal 32-bit code with the @samp{.code32} directive.
+be run in 16-bit mode. You can switch @code{@value{AS}} to writing
+32-bit code with the @samp{.code32} directive or 64-bit code with the
+@samp{.code64} directive.
@samp{.code16gcc} provides experimental support for generating 16-bit
code from gcc, and differs from @samp{.code16} in that @samp{call},
@item @samp{i486} @tab @samp{i586} @tab @samp{i686} @tab @samp{pentium}
@item @samp{pentiumpro} @tab @samp{pentiumii} @tab @samp{pentiumiii} @tab @samp{pentium4}
@item @samp{prescott} @tab @samp{nocona} @tab @samp{core} @tab @samp{core2}
+@item @samp{corei7} @tab @samp{l1om}
@item @samp{k6} @tab @samp{k6_2} @tab @samp{athlon} @tab @samp{k8}
-@item @samp{amdfam10}
+@item @samp{amdfam10} @tab @samp{bdver1} @tab @samp{bdver2}
@item @samp{generic32} @tab @samp{generic64}
@item @samp{.mmx} @tab @samp{.sse} @tab @samp{.sse2} @tab @samp{.sse3}
@item @samp{.ssse3} @tab @samp{.sse4.1} @tab @samp{.sse4.2} @tab @samp{.sse4}
-@item @samp{.avx} @tab @samp{.vmx} @tab @samp{.smx} @tab @samp{.xsave}
-@item @samp{.aes} @tab @samp{.clmul} @tab @samp{.fma}
+@item @samp{.avx} @tab @samp{.vmx} @tab @samp{.smx} @tab @samp{.ept}
+@item @samp{.clflush} @tab @samp{.movbe} @tab @samp{.xsave} @tab @samp{.xsaveopt}
+@item @samp{.aes} @tab @samp{.pclmul} @tab @samp{.fma} @tab @samp{.fsgsbase}
+@item @samp{.rdrnd} @tab @samp{.f16c} @tab @samp{.avx2} @tab @samp{.bmi2}
+@item @samp{.lzcnt} @tab @samp{.invpcid}
@item @samp{.3dnow} @tab @samp{.3dnowa} @tab @samp{.sse4a} @tab @samp{.sse5}
-@item @samp{.svme} @tab @samp{.abm}
+@item @samp{.syscall} @tab @samp{.rdtscp} @tab @samp{.svme} @tab @samp{.abm}
+@item @samp{.lwp} @tab @samp{.fma4} @tab @samp{.xop}
@item @samp{.padlock}
@end multitable
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