gas/doc/c-rx.texi - binutils-gdb - Git at Google

 @c Copyright (C) 2008-2021 Free Software Foundation, Inc.
 @c This is part of the GAS manual.
 @c For copying conditions, see the file as.texinfo.
 @ifset GENERIC
 @page
 @node RX-Dependent
 @chapter RX Dependent Features
 @end ifset
 @ifclear GENERIC
 @node Machine Dependencies
 @chapter RX Dependent Features
 @end ifclear

 @cindex RX support
 @menu
 * RX-Opts::                   RX Assembler Command-line Options
 * RX-Modifiers::              Symbolic Operand Modifiers
 * RX-Directives::             Assembler Directives
 * RX-Float::                  Floating Point
 * RX-Syntax::                 Syntax
 @end menu

 @node RX-Opts
 @section RX Options
 @cindex options, RX
 @cindex RX options

 The Renesas RX port of @code{@value{AS}} has a few target specific
 command-line options:

 @table @code

 @cindex @samp{-m32bit-doubles}
 @item -m32bit-doubles
 This option controls the ABI and indicates to use a 32-bit float ABI.
 It has no effect on the assembled instructions, but it does influence
 the behaviour of the @samp{.double} pseudo-op.
 This is the default.

 @cindex @samp{-m64bit-doubles}
 @item -m64bit-doubles
 This option controls the ABI and indicates to use a 64-bit float ABI.
 It has no effect on the assembled instructions, but it does influence
 the behaviour of the @samp{.double} pseudo-op.

 @cindex @samp{-mbig-endian}
 @item -mbig-endian
 This option controls the ABI and indicates to use a big-endian data
 ABI.  It has no effect on the assembled instructions, but it does
 influence the behaviour of the @samp{.short}, @samp{.hword}, @samp{.int},
 @samp{.word}, @samp{.long}, @samp{.quad} and @samp{.octa} pseudo-ops.

 @cindex @samp{-mlittle-endian}
 @item -mlittle-endian
 This option controls the ABI and indicates to use a little-endian data
 ABI.  It has no effect on the assembled instructions, but it does
 influence the behaviour of the @samp{.short}, @samp{.hword}, @samp{.int},
 @samp{.word}, @samp{.long}, @samp{.quad} and @samp{.octa} pseudo-ops.
 This is the default.

 @cindex @samp{-muse-conventional-section-names}
 @item -muse-conventional-section-names
 This option controls the default names given to the code (.text),
 initialised data (.data) and uninitialised data sections (.bss).

 @cindex @samp{-muse-renesas-section-names}
 @item -muse-renesas-section-names
 This option controls the default names given to the code (P),
 initialised data (D_1) and uninitialised data sections (B_1).
 This is the default.

 @cindex @samp{-msmall-data-limit}
 @item -msmall-data-limit
 This option tells the assembler that the small data limit feature of
 the RX port of GCC is being used.  This results in the assembler
 generating an undefined reference to a symbol called @code{__gp} for
 use by the relocations that are needed to support the small data limit
 feature.   This option is not enabled by default as it would otherwise
 pollute the symbol table.

 @cindex @samp{-mpid}
 @item -mpid
 This option tells the assembler that the position independent data of the
 RX port of GCC is being used.  This results in the assembler
 generating an undefined reference to a symbol called @code{__pid_base},
 and also setting the RX_PID flag bit in the e_flags field of the ELF
 header of the object file.

 @cindex @samp{-mint-register}
 @item -mint-register=@var{num}
 This option tells the assembler how many registers have been reserved
 for use by interrupt handlers.  This is needed in order to compute the
 correct values for the @code{%gpreg} and @code{%pidreg} meta registers.

 @cindex @samp{-mgcc-abi}
 @item -mgcc-abi
 This option tells the assembler that the old GCC ABI is being used by
 the assembled code.  With this version of the ABI function arguments
 that are passed on the stack are aligned to a 32-bit boundary.

 @cindex @samp{-mrx-abi}
 @item -mrx-abi
 This option tells the assembler that the official RX ABI is being used
 by the assembled code.  With this version of the ABI function
 arguments that are passed on the stack are aligned to their natural
 alignments.  This option is the default.

 @cindex @samp{-mcpu=}
 @item -mcpu=@var{name}
 This option tells the assembler the target CPU type.  Currently the
 @code{rx100}, @code{rx200}, @code{rx600}, @code{rx610}, @code{rxv2},
 @code{rxv3} and @code{rxv3-dfpu} are recognised as valid cpu names.
 Attempting to assemble an instructionnot supported by the indicated
 cpu type will result in an error message being generated.

 @cindex @samp{-mno-allow-string-insns}
 @item -mno-allow-string-insns
 This option tells the assembler to mark the object file that it is
 building as one that does not use the string instructions
 @code{SMOVF}, @code{SCMPU}, @code{SMOVB}, @code{SMOVU}, @code{SUNTIL}
 @code{SWHILE} or the @code{RMPA} instruction.  In addition the mark
 tells the linker to complain if an attempt is made to link the binary
 with another one that does use any of these instructions.

 Note - the inverse of this option, @code{-mallow-string-insns}, is
 not needed.  The assembler automatically detects the use of the
 the instructions in the source code and labels the resulting
 object file appropriately.  If no string instructions are detected
 then the object file is labelled as being one that can be linked with
 either string-using or string-banned object files.
 @end table

 @node RX-Modifiers
 @section Symbolic Operand Modifiers

 @cindex RX modifiers
 @cindex syntax, RX
 @cindex %gp

 The assembler supports one modifier when using symbol addresses
 in RX instruction operands.  The general syntax is the following:

 @smallexample
 %gp(symbol)
 @end smallexample

 The modifier returns the offset from the @var{__gp} symbol to the
 specified symbol as a 16-bit value.  The intent is that this offset
 should be used in a register+offset move instruction when generating
 references to small data.  Ie, like this:

 @smallexample
   mov.W	 %gp(_foo)[%gpreg], r1
 @end smallexample

 The assembler also supports two meta register names which can be used
 to refer to registers whose values may not be known to the
 programmer.  These meta register names are:

 @table @code

 @cindex @samp{%gpreg}
 @item %gpreg
 The small data address register.

 @cindex @samp{%pidreg}
 @item %pidreg
 The PID base address register.

 @end table

 Both registers normally have the value r13, but this can change if
 some registers have been reserved for use by interrupt handlers or if
 both the small data limit and position independent data features are
 being used at the same time.

 @node RX-Directives
 @section Assembler Directives

 @cindex assembler directives, RX
 @cindex RX assembler directives

 The RX version of @code{@value{AS}} has the following specific
 assembler directives:

 @table @code

 @item .3byte
 @cindex assembler directive .3byte, RX
 @cindex RX assembler directive .3byte
 Inserts a 3-byte value into the output file at the current location.

 @item .fetchalign
 @cindex assembler directive .fetchalign, RX
 @cindex RX assembler directive .fetchalign
 If the next opcode following this directive spans a fetch line
 boundary (8 byte boundary), the opcode is aligned to that boundary.
 If the next opcode does not span a fetch line, this directive has no
 effect.  Note that one or more labels may be between this directive
 and the opcode; those labels are aligned as well.  Any inserted bytes
 due to alignment will form a NOP opcode.

 @end table

 @node RX-Float
 @section Floating Point

 @cindex floating point, RX
 @cindex RX floating point

 The floating point formats generated by directives are these.

 @table @code
 @cindex @code{float} directive, RX

 @item .float
 @code{Single} precision (32-bit) floating point constants.

 @cindex @code{double} directive, RX
 @item .double
 If the @option{-m64bit-doubles} command-line option has been specified
 then then @code{double} directive generates @code{double} precision
 (64-bit) floating point constants, otherwise it generates
 @code{single} precision (32-bit) floating point constants.  To force
 the generation of 64-bit floating point constants used the @code{dc.d}
 directive instead.

 @end table

 @node RX-Syntax
 @section Syntax for the RX
 @menu
 * RX-Chars::                Special Characters
 @end menu

 @node RX-Chars
 @subsection Special Characters

 @cindex line comment character, RX
 @cindex RX 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}).

 @cindex line separator, RX
 @cindex statement separator, RX
 @cindex RX line separator
 The @samp{!} character can be used to separate statements on the same
 line.
	@c Copyright (C) 2008-2021 Free Software Foundation, Inc.
	@c This is part of the GAS manual.
	@c For copying conditions, see the file as.texinfo.
	@ifset GENERIC
	@page
	@node RX-Dependent
	@chapter RX Dependent Features
	@end ifset
	@ifclear GENERIC
	@node Machine Dependencies
	@chapter RX Dependent Features
	@end ifclear

	@cindex RX support
	@menu
	* RX-Opts:: RX Assembler Command-line Options
	* RX-Modifiers:: Symbolic Operand Modifiers
	* RX-Directives:: Assembler Directives
	* RX-Float:: Floating Point
	* RX-Syntax:: Syntax
	@end menu

	@node RX-Opts
	@section RX Options
	@cindex options, RX
	@cindex RX options

	The Renesas RX port of @code{@value{AS}} has a few target specific
	command-line options:

	@table @code

	@cindex @samp{-m32bit-doubles}
	@item -m32bit-doubles
	This option controls the ABI and indicates to use a 32-bit float ABI.
	It has no effect on the assembled instructions, but it does influence
	the behaviour of the @samp{.double} pseudo-op.
	This is the default.

	@cindex @samp{-m64bit-doubles}
	@item -m64bit-doubles
	This option controls the ABI and indicates to use a 64-bit float ABI.
	It has no effect on the assembled instructions, but it does influence
	the behaviour of the @samp{.double} pseudo-op.

	@cindex @samp{-mbig-endian}
	@item -mbig-endian
	This option controls the ABI and indicates to use a big-endian data
	ABI. It has no effect on the assembled instructions, but it does
	influence the behaviour of the @samp{.short}, @samp{.hword}, @samp{.int},
	@samp{.word}, @samp{.long}, @samp{.quad} and @samp{.octa} pseudo-ops.

	@cindex @samp{-mlittle-endian}
	@item -mlittle-endian
	This option controls the ABI and indicates to use a little-endian data
	ABI. It has no effect on the assembled instructions, but it does
	influence the behaviour of the @samp{.short}, @samp{.hword}, @samp{.int},
	@samp{.word}, @samp{.long}, @samp{.quad} and @samp{.octa} pseudo-ops.
	This is the default.

	@cindex @samp{-muse-conventional-section-names}
	@item -muse-conventional-section-names
	This option controls the default names given to the code (.text),
	initialised data (.data) and uninitialised data sections (.bss).

	@cindex @samp{-muse-renesas-section-names}
	@item -muse-renesas-section-names
	This option controls the default names given to the code (P),
	initialised data (D_1) and uninitialised data sections (B_1).
	This is the default.

	@cindex @samp{-msmall-data-limit}
	@item -msmall-data-limit
	This option tells the assembler that the small data limit feature of
	the RX port of GCC is being used. This results in the assembler
	generating an undefined reference to a symbol called @code{__gp} for
	use by the relocations that are needed to support the small data limit
	feature. This option is not enabled by default as it would otherwise
	pollute the symbol table.

	@cindex @samp{-mpid}
	@item -mpid
	This option tells the assembler that the position independent data of the
	RX port of GCC is being used. This results in the assembler
	generating an undefined reference to a symbol called @code{__pid_base},
	and also setting the RX_PID flag bit in the e_flags field of the ELF
	header of the object file.

	@cindex @samp{-mint-register}
	@item -mint-register=@var{num}
	This option tells the assembler how many registers have been reserved
	for use by interrupt handlers. This is needed in order to compute the
	correct values for the @code{%gpreg} and @code{%pidreg} meta registers.

	@cindex @samp{-mgcc-abi}
	@item -mgcc-abi
	This option tells the assembler that the old GCC ABI is being used by
	the assembled code. With this version of the ABI function arguments
	that are passed on the stack are aligned to a 32-bit boundary.

	@cindex @samp{-mrx-abi}
	@item -mrx-abi
	This option tells the assembler that the official RX ABI is being used
	by the assembled code. With this version of the ABI function
	arguments that are passed on the stack are aligned to their natural
	alignments. This option is the default.

	@cindex @samp{-mcpu=}
	@item -mcpu=@var{name}
	This option tells the assembler the target CPU type. Currently the
	@code{rx100}, @code{rx200}, @code{rx600}, @code{rx610}, @code{rxv2},
	@code{rxv3} and @code{rxv3-dfpu} are recognised as valid cpu names.
	Attempting to assemble an instructionnot supported by the indicated
	cpu type will result in an error message being generated.

	@cindex @samp{-mno-allow-string-insns}
	@item -mno-allow-string-insns
	This option tells the assembler to mark the object file that it is
	building as one that does not use the string instructions
	@code{SMOVF}, @code{SCMPU}, @code{SMOVB}, @code{SMOVU}, @code{SUNTIL}
	@code{SWHILE} or the @code{RMPA} instruction. In addition the mark
	tells the linker to complain if an attempt is made to link the binary
	with another one that does use any of these instructions.

	Note - the inverse of this option, @code{-mallow-string-insns}, is
	not needed. The assembler automatically detects the use of the
	the instructions in the source code and labels the resulting
	object file appropriately. If no string instructions are detected
	then the object file is labelled as being one that can be linked with
	either string-using or string-banned object files.
	@end table

	@node RX-Modifiers
	@section Symbolic Operand Modifiers

	@cindex RX modifiers
	@cindex syntax, RX
	@cindex %gp

	The assembler supports one modifier when using symbol addresses
	in RX instruction operands. The general syntax is the following:

	@smallexample
	%gp(symbol)
	@end smallexample

	The modifier returns the offset from the @var{__gp} symbol to the
	specified symbol as a 16-bit value. The intent is that this offset
	should be used in a register+offset move instruction when generating
	references to small data. Ie, like this:

	@smallexample
	mov.W %gp(_foo)[%gpreg], r1
	@end smallexample

	The assembler also supports two meta register names which can be used
	to refer to registers whose values may not be known to the
	programmer. These meta register names are:

	@table @code

	@cindex @samp{%gpreg}
	@item %gpreg
	The small data address register.

	@cindex @samp{%pidreg}
	@item %pidreg
	The PID base address register.

	@end table

	Both registers normally have the value r13, but this can change if
	some registers have been reserved for use by interrupt handlers or if
	both the small data limit and position independent data features are
	being used at the same time.

	@node RX-Directives
	@section Assembler Directives

	@cindex assembler directives, RX
	@cindex RX assembler directives

	The RX version of @code{@value{AS}} has the following specific
	assembler directives:

	@table @code

	@item .3byte
	@cindex assembler directive .3byte, RX
	@cindex RX assembler directive .3byte
	Inserts a 3-byte value into the output file at the current location.

	@item .fetchalign
	@cindex assembler directive .fetchalign, RX
	@cindex RX assembler directive .fetchalign
	If the next opcode following this directive spans a fetch line
	boundary (8 byte boundary), the opcode is aligned to that boundary.
	If the next opcode does not span a fetch line, this directive has no
	effect. Note that one or more labels may be between this directive
	and the opcode; those labels are aligned as well. Any inserted bytes
	due to alignment will form a NOP opcode.

	@end table

	@node RX-Float
	@section Floating Point

	@cindex floating point, RX
	@cindex RX floating point

	The floating point formats generated by directives are these.

	@table @code
	@cindex @code{float} directive, RX

	@item .float
	@code{Single} precision (32-bit) floating point constants.

	@cindex @code{double} directive, RX
	@item .double
	If the @option{-m64bit-doubles} command-line option has been specified
	then then @code{double} directive generates @code{double} precision
	(64-bit) floating point constants, otherwise it generates
	@code{single} precision (32-bit) floating point constants. To force
	the generation of 64-bit floating point constants used the @code{dc.d}
	directive instead.

	@end table

	@node RX-Syntax
	@section Syntax for the RX
	@menu
	* RX-Chars:: Special Characters
	@end menu

	@node RX-Chars
	@subsection Special Characters

	@cindex line comment character, RX
	@cindex RX 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}).

	@cindex line separator, RX
	@cindex statement separator, RX
	@cindex RX line separator
	The @samp{!} character can be used to separate statements on the same
	line.