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These `-m' options are defined for the IBM RS/6000 and PowerPC:
-mpower
-
-mno-power
-
-mpower2
-
-mno-power2
-
-mpowerpc
-
-mno-powerpc
-
-mpowerpc-gpopt
-
-mno-powerpc-gpopt
-
-mpowerpc-gfxopt
-
-mno-powerpc-gfxopt
-
GNU CC supports two related instruction set architectures for the
RS/6000 and PowerPC. The POWER instruction set are those
instructions supported by the `rios' chip set used in the original
RS/6000 systems and the PowerPC instruction set is the
architecture of the Motorola MPC5xx, MPC6xx, MPC8xx microprocessors, and
the IBM 4xx microprocessors.
Neither architecture is a subset of the other. However there is a
large common subset of instructions supported by both. An MQ
register is included in processors supporting the POWER architecture.
You use these options to specify which instructions are available on the
processor you are using. The default value of these options is
determined when configuring GNU CC. Specifying the
`-mcpu=cpu_type' overrides the specification of these
options. We recommend you use the `-mcpu=cpu_type' option
rather than the options listed above.
The `-mpower' option allows GNU CC to generate instructions that
are found only in the POWER architecture and to use the MQ register.
Specifying `-mpower2' implies `-power' and also allows GNU CC
to generate instructions that are present in the POWER2 architecture but
not the original POWER architecture.
The `-mpowerpc' option allows GNU CC to generate instructions that
are found only in the 32-bit subset of the PowerPC architecture.
Specifying `-mpowerpc-gpopt' implies `-mpowerpc' and also allows
GNU CC to use the optional PowerPC architecture instructions in the
General Purpose group, including floating-point square root. Specifying
`-mpowerpc-gfxopt' implies `-mpowerpc' and also allows GNU CC to
use the optional PowerPC architecture instructions in the Graphics
group, including floating-point select.
If you specify both `-mno-power' and `-mno-powerpc', GNU CC
will use only the instructions in the common subset of both
architectures plus some special AIX common-mode calls, and will not use
the MQ register. Specifying both `-mpower' and `-mpowerpc'
permits GNU CC to use any instruction from either architecture and to
allow use of the MQ register; specify this for the Motorola MPC601.
-mnew-mnemonics
-
-mold-mnemonics
-
Select which mnemonics to use in the generated assembler code.
`-mnew-mnemonics' requests output that uses the assembler mnemonics
defined for the PowerPC architecture, while `-mold-mnemonics'
requests the assembler mnemonics defined for the POWER architecture.
Instructions defined in only one architecture have only one mnemonic;
GNU CC uses that mnemonic irrespective of which of these options is
specified.
PowerPC assemblers support both the old and new mnemonics, as will later
POWER assemblers. Current POWER assemblers only support the old
mnemonics. Specify `-mnew-mnemonics' if you have an assembler that
supports them, otherwise specify `-mold-mnemonics'.
The default value of these options depends on how GNU CC was configured.
Specifying `-mcpu=cpu_type' sometimes overrides the value of
these option. Unless you are building a cross-compiler, you should
normally not specify either `-mnew-mnemonics' or
`-mold-mnemonics', but should instead accept the default.
-mcpu=cpu_type
-
Set architecture type, register usage, choice of mnemonics, and
instruction scheduling parameters for machine type cpu_type.
Supported values for cpu_type are `rs6000', `rios1',
`rios2', `rsc', `601', `602', `603',
`603e', `604', `604e', `620', `power',
`power2', `powerpc', `403', `505', `801',
`821', `823', and `860' and `common'.
`-mcpu=power', `-mcpu=power2', and `-mcpu=powerpc'
specify generic POWER, POWER2 and pure PowerPC (i.e., not MPC601)
architecture machine types, with an appropriate, generic processor model
assumed for scheduling purposes.
Specifying any of the following options:
`-mcpu=rios1', `-mcpu=rios2', `-mcpu=rsc',
`-mcpu=power', or `-mcpu=power2'
enables the `-mpower' option and disables the `-mpowerpc' option;
`-mcpu=601' enables both the `-mpower' and `-mpowerpc' options.
All of `-mcpu=602', `-mcpu=603', `-mcpu=603e',
`-mcpu=604', `-mcpu=620',
enable the `-mpowerpc' option and disable the `-mpower' option.
Exactly similarly, all of `-mcpu=403',
`-mcpu=505', `-mcpu=821', `-mcpu=860' and `-mcpu=powerpc'
enable the `-mpowerpc' option and disable the `-mpower' option.
`-mcpu=common' disables both the
`-mpower' and `-mpowerpc' options.
AIX versions 4 or greater selects `-mcpu=common' by default, so
that code will operate on all members of the RS/6000 and PowerPC
families. In that case, GNU CC will use only the instructions in the
common subset of both architectures plus some special AIX common-mode
calls, and will not use the MQ register. GNU CC assumes a generic
processor model for scheduling purposes.
Specifying any of the options `-mcpu=rios1', `-mcpu=rios2',
`-mcpu=rsc', `-mcpu=power', or `-mcpu=power2' also
disables the `new-mnemonics' option. Specifying `-mcpu=601',
`-mcpu=602', `-mcpu=603', `-mcpu=603e', `-mcpu=604',
`620', `403', or `-mcpu=powerpc' also enables the
`new-mnemonics' option.
Specifying `-mcpu=403', `-mcpu=821', or `-mcpu=860' also
enables the `-msoft-float' option.
-mtune=cpu_type
-
Set the instruction scheduling parameters for machine type
cpu_type, but do not set the architecture type, register usage,
choice of mnemonics like `-mcpu='cpu_type would. The same
values for cpu_type are used for `-mtune='cpu_type as
for `-mcpu='cpu_type. The `-mtune='cpu_type
option overrides the `-mcpu='cpu_type option in terms of
instruction scheduling parameters.
-mfull-toc
-
-mno-fp-in-toc
-
-mno-sum-in-toc
-
-mminimal-toc
-
Modify generation of the TOC (Table Of Contents), which is created for
every executable file. The `-mfull-toc' option is selected by
default. In that case, GNU CC will allocate at least one TOC entry for
each unique non-automatic variable reference in your program. GNU CC
will also place floating-point constants in the TOC. However, only
16,384 entries are available in the TOC.
If you receive a linker error message that saying you have overflowed
the available TOC space, you can reduce the amount of TOC space used
with the `-mno-fp-in-toc' and `-mno-sum-in-toc' options.
`-mno-fp-in-toc' prevents GNU CC from putting floating-point
constants in the TOC and `-mno-sum-in-toc' forces GNU CC to
generate code to calculate the sum of an address and a constant at
run-time instead of putting that sum into the TOC. You may specify one
or both of these options. Each causes GNU CC to produce very slightly
slower and larger code at the expense of conserving TOC space.
If you still run out of space in the TOC even when you specify both of
these options, specify `-mminimal-toc' instead. This option causes
GNU CC to make only one TOC entry for every file. When you specify this
option, GNU CC will produce code that is slower and larger but which
uses extremely little TOC space. You may wish to use this option
only on files that contain less frequently executed code.
-mxl-call
-
-mno-xl-call
-
On AIX, pass floating-point arguments to prototyped functions beyond the
register save area (RSA) on the stack in addition to argument FPRs. The
AIX calling convention was extended but not initially documented to
handle an obscure K&R C case of calling a function that takes the
address of its arguments with fewer arguments than declared. AIX XL
compilers assume that floating point arguments which do not fit in the
RSA are on the stack when they compile a subroutine without
optimization. Because always storing floating-point arguments on the
stack is inefficient and rarely needed, this option is not enabled by
default and only is necessary when calling subroutines compiled by AIX
XL compilers without optimization.
-mthreads
-
Support AIX Threads. Link an application written to use
pthreads with special libraries and startup code to enable the
application to run.
-mpe
-
Support IBM RS/6000 SP Parallel Environment (PE). Link an
application written to use message passing with special startup code to
enable the application to run. The system must have PE installed in the
standard location (`/usr/lpp/ppe.poe/'), or the `specs' file
must be overridden with the `-specs=' option to specify the
appropriate directory location. The Parallel Environment does not
support threads, so the `-mpe' option and the `-mthreads'
option are incompatible.
-msoft-float
-
-mhard-float
-
Generate code that does not use (uses) the floating-point register set.
Software floating point emulation is provided if you use the
`-msoft-float' option, and pass the option to GNU CC when linking.
-mmultiple
-
-mno-multiple
-
Generate code that uses (does not use) the load multiple word
instructions and the store multiple word instructions. These
instructions are generated by default on POWER systems, and not
generated on PowerPC systems. Do not use `-mmultiple' on little
endian PowerPC systems, since those instructions do not work when the
processor is in little endian mode.
-mstring
-
-mno-string
-
Generate code that uses (does not use) the load string instructions and the
store string word instructions to save multiple registers and do small block
moves. These instructions are generated by default on POWER systems, and not
generated on PowerPC systems. Do not use `-mstring' on little endian
PowerPC systems, since those instructions do not work when the processor is in
little endian mode.
-mupdate
-
-mno-update
-
Generate code that uses (does not use) the load or store instructions
that update the base register to the address of the calculated memory
location. These instructions are generated by default. If you use
`-mno-update', there is a small window between the time that the
stack pointer is updated and the address of the previous frame is
stored, which means code that walks the stack frame across interrupts or
signals may get corrupted data.
-mfused-madd
-
-mno-fused-madd
-
Generate code that uses (does not use) the floating point multiply and
accumulate instructions. These instructions are generated by default if
hardware floating is used.
-mno-bit-align
-
-mbit-align
-
On System V.4 and embedded PowerPC systems do not (do) force structures
and unions that contain bit fields to be aligned to the base type of the
bit field.
For example, by default a structure containing nothing but 8
unsigned bitfields of length 1 would be aligned to a 4 byte
boundary and have a size of 4 bytes. By using `-mno-bit-align',
the structure would be aligned to a 1 byte boundary and be one byte in
size.
-mno-strict-align
-
-mstrict-align
-
On System V.4 and embedded PowerPC systems do not (do) assume that
unaligned memory references will be handled by the system.
-mrelocatable
-
-mno-relocatable
-
On embedded PowerPC systems generate code that allows (does not allow)
the program to be relocated to a different address at runtime. If you
use `-mrelocatable' on any module, all objects linked together must
be compiled with `-mrelocatable' or `-mrelocatable-lib'.
-mrelocatable-lib
-
-mno-relocatable-lib
-
On embedded PowerPC systems generate code that allows (does not allow)
the program to be relocated to a different address at runtime. Modules
compiled with `-mreloctable-lib' can be linked with either modules
compiled without `-mrelocatable' and `-mrelocatable-lib' or
with modules compiled with the `-mrelocatable' options.
-mno-toc
-
-mtoc
-
On System V.4 and embedded PowerPC systems do not (do) assume that
register 2 contains a pointer to a global area pointing to the addresses
used in the program.
-mno-traceback
-
-mtraceback
-
On embedded PowerPC systems do not (do) generate a traceback tag before
the start of the function. This tag can be used by the debugger to
identify where the start of a function is.
-mlittle
-
-mlittle-endian
-
On System V.4 and embedded PowerPC systems compile code for the
processor in little endian mode. The `-mlittle-endian' option is
the same as `-mlittle'.
-mbig
-
-mbig-endian
-
On System V.4 and embedded PowerPC systems compile code for the
processor in big endian mode. The `-mbig-endian' option is
the same as `-mbig'.
-mcall-sysv
-
On System V.4 and embedded PowerPC systems compile code using calling
conventions that adheres to the March 1995 draft of the System V
Application Binary Interface, PowerPC processor supplement. This is the
default unless you configured GCC using `powerpc-*-eabiaix'.
-mcall-sysv-eabi
-
Specify both `-mcall-sysv' and `-meabi' options.
-mcall-sysv-noeabi
-
Specify both `-mcall-sysv' and `-mno-eabi' options.
-mcall-aix
-
On System V.4 and embedded PowerPC systems compile code using calling
conventions that are similar to those used on AIX. This is the
default if you configured GCC using `powerpc-*-eabiaix'.
-mcall-solaris
-
On System V.4 and embedded PowerPC systems compile code for the Solaris
operating system.
-mcall-linux
-
On System V.4 and embedded PowerPC systems compile code for the
Linux-based GNU system.
-mprototype
-
-mno-prototype
-
On System V.4 and embedded PowerPC systems assume that all calls to
variable argument functions are properly prototyped. Otherwise, the
compiler must insert an instruction before every non prototyped call to
set or clear bit 6 of the condition code register (CR) to
indicate whether floating point values were passed in the floating point
registers in case the function takes a variable arguments. With
`-mprototype', only calls to prototyped variable argument functions
will set or clear the bit.
-msim
-
On embedded PowerPC systems, assume that the startup module is called
`sim-crt0.o' and that the standard C libraries are `libsim.a' and
`libc.a'. This is the default for `powerpc-*-eabisim'.
configurations.
-mmvme
-
On embedded PowerPC systems, assume that the startup module is called
`mvme-crt0.o' and the standard C libraries are `libmvme.a' and
`libc.a'.
-memb
-
On embedded PowerPC systems, set the PPC_EMB bit in the ELF flags
header to indicate that `eabi' extended relocations are used.
-meabi
-
-mno-eabi
-
On System V.4 and embedded PowerPC systems do (do not) adhere to the
Embedded Applications Binary Interface (eabi) which is a set of
modifications to the System V.4 specifications. Selecting
-meabi
means that the stack is aligned to an 8 byte boundary, a function
__eabi is called to from main to set up the eabi
environment, and the `-msdata' option can use both r2 and
r13 to point to two separate small data areas. Selecting
-mno-eabi means that the stack is aligned to a 16 byte boundary,
do not call an initialization function from main, and the
`-msdata' option will only use r13 to point to a single
small data area. The `-meabi' option is on by default if you
configured GCC using one of the `powerpc*-*-eabi*' options.
-msdata=eabi
-
On System V.4 and embedded PowerPC systems, put small initialized
const global and static data in the `.sdata2' section, which
is pointed to by register r2. Put small initialized
non-const global and static data in the `.sdata' section,
which is pointed to by register r13. Put small uninitialized
global and static data in the `.sbss' section, which is adjacent to
the `.sdata' section. The `-msdata=eabi' option is
incompatible with the `-mrelocatable' option. The
`-msdata=eabi' option also sets the `-memb' option.
-msdata=sysv
-
On System V.4 and embedded PowerPC systems, put small global and static
data in the `.sdata' section, which is pointed to by register
r13. Put small uninitialized global and static data in the
`.sbss' section, which is adjacent to the `.sdata' section.
The `-msdata=sysv' option is incompatible with the
`-mrelocatable' option.
-msdata=default
-
-msdata
-
On System V.4 and embedded PowerPC systems, if `-meabi' is used,
compile code the same as `-msdata=eabi', otherwise compile code the
same as `-msdata=sysv'.
-msdata-data
-
On System V.4 and embedded PowerPC systems, put small global and static
data in the `.sdata' section. Put small uninitialized global and
static data in the `.sbss' section. Do not use register
r13
to address small data however. This is the default behavior unless
other `-msdata' options are used.
-msdata=none
-
-mno-sdata
-
On embedded PowerPC systems, put all initialized global and static data
in the `.data' section, and all uninitialized data in the
`.bss' section.
-G num
-
On embbeded PowerPC systems, put global and static items less than or
equal to num bytes into the small data or bss sections instead of
the normal data or bss section. By default, num is 8. The
`-G num' switch is also passed to the linker.
All modules should be compiled with the same `-G num' value.
-mregnames
-
-mno-regnames
-
On System V.4 and embedded PowerPC systems do (do not) emit register
names in the assembly language output using symbolic forms.
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