-mpower-mno-power-mpower2-mno-power2-mpowerpc-mno-powerpc-mpowerpc-gpopt-mno-powerpc-gpopt-mpowerpc-gfxopt-mno-powerpc-gfxopt-mpowerpc64-mno-powerpc64- GCC 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 GCC. 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 GCC to generate instructions that
are found only in the POWER architecture and to use the MQ register.
Specifying -mpower2 implies -power and also allows GCC
to generate instructions that are present in the POWER2 architecture but
not the original POWER architecture.
The -mpowerpc option allows GCC to generate instructions that
are found only in the 32-bit subset of the PowerPC architecture.
Specifying -mpowerpc-gpopt implies -mpowerpc and also allows
GCC 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 GCC to
use the optional PowerPC architecture instructions in the Graphics
group, including floating-point select.
The -mpowerpc64 option allows GCC to generate the additional
64-bit instructions that are found in the full PowerPC64 architecture
and to treat GPRs as 64-bit, doubleword quantities. GCC defaults to
-mno-powerpc64.
If you specify both -mno-power and -mno-powerpc, GCC
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 GCC 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. With
-mnew-mnemonics, GCC uses the assembler mnemonics defined for
the PowerPC architecture. With -mold-mnemonics it uses the
assembler mnemonics defined for the POWER architecture. Instructions
defined in only one architecture have only one mnemonic; GCC uses that
mnemonic irrespective of which of these options is specified.
GCC defaults to the mnemonics appropriate for the architecture in
use. 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 `rios', `rios1',
`rsc', `rios2', `rs64a', `601', `602',
`603', `603e', `604', `604e', `620',
`630', `740', `7400', `7450', `750',
`power', `power2', `powerpc', `403', `505',
`801', `821', `823', and `860' and `common'.
-mcpu=common selects a completely generic processor. Code
generated under this option will run on any POWER or PowerPC processor.
GCC will use only the instructions in the common subset of both
architectures, and will not use the MQ register. GCC assumes a generic
processor model for scheduling purposes.
-mcpu=power, -mcpu=power2, -mcpu=powerpc, and
-mcpu=powerpc64 specify generic POWER, POWER2, pure 32-bit
PowerPC (i.e., not MPC601), and 64-bit PowerPC architecture machine
types, with an appropriate, generic processor model assumed for
scheduling purposes.
The other options specify a specific processor. Code generated under
those options will run best on that processor, and may not run at all on
others.
The -mcpu options automatically enable or disable other
-m options as follows:
- `common'
- -mno-power, -mno-powerpc
- `power'
- `power2'
- `rios1'
- `rios2'
- `rsc'
- -mpower, -mno-powerpc, -mno-new-mnemonics
- `powerpc'
- `rs64a'
- `602'
- `603'
- `603e'
- `604'
- `620'
- `630'
- `740'
- `7400'
- `7450'
- `750'
- `505'
- -mno-power, -mpowerpc, -mnew-mnemonics
- `601'
- -mpower, -mpowerpc, -mnew-mnemonics
- `403'
- `821'
- `860'
- -mno-power, -mpowerpc, -mnew-mnemonics, -msoft-float
-mtune=cpu_type- Set the instruction scheduling parameters for machine type
cpu_type, but do not set the architecture type, register usage, or
choice of mnemonics, as -mcpu=cpu_type would. The same
values for cpu_type are used for -mtune as for
-mcpu. If both are specified, the code generated will use the
architecture, registers, and mnemonics set by -mcpu, but the
scheduling parameters set by -mtune.
-maltivec-mno-altivec- These switches enable or disable the use of built-in functions that
allow access to the AltiVec instruction set. You may also need to set
-mabi=altivec to adjust the current ABI with AltiVec ABI
enhancements.
-mabi=spe- Extend the current ABI with SPE ABI extensions. This does not change
the default ABI, instead it adds the SPE ABI extensions to the current
ABI.
-mabi=no-spe- Disable Booke SPE ABI extensions for the current ABI.
-misel=yes/no-misel- This switch enables or disables the generation of ISEL instructions.
-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, GCC will allocate at least one TOC entry for
each unique non-automatic variable reference in your program. GCC
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 GCC from putting floating-point
constants in the TOC and -mno-sum-in-toc forces GCC 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 GCC 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
GCC to make only one TOC entry for every file. When you specify this
option, GCC 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.
-maix64-maix32- Enable 64-bit AIX ABI and calling convention: 64-bit pointers, 64-bit
long type, and the infrastructure needed to support them.
Specifying -maix64 implies -mpowerpc64 and
-mpowerpc, while -maix32 disables the 64-bit ABI and
implies -mno-powerpc64. GCC defaults to -maix32.
-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 access floating point arguments which do not fit in the
RSA from the stack when a subroutine is compiled 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.
-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 -pthread
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 GCC 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. The exceptions are PPC740 and
PPC750 which permit the instructions usage 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.
The exceptions are PPC740 and PPC750 which permit the instructions
usage 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 bit-fields 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 -mrelocatable-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.
-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.
-mcall-gnu- On System V.4 and embedded PowerPC systems compile code for the
Hurd-based GNU system.
-mcall-netbsd- On System V.4 and embedded PowerPC systems compile code for the
NetBSD operating system.
-maix-struct-return- Return all structures in memory (as specified by the AIX ABI).
-msvr4-struct-return- Return structures smaller than 8 bytes in registers (as specified by the
SVR4 ABI).
-mabi=altivec- Extend the current ABI with AltiVec ABI extensions. This does not
change the default ABI, instead it adds the AltiVec ABI extensions to
the current ABI.
-mabi=no-altivec- Disable AltiVec ABI extensions for the current ABI.
-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
crt0.o and the standard C libraries are libmvme.a and
libc.a.
-mads- On embedded PowerPC systems, assume that the startup module is called
crt0.o and the standard C libraries are libads.a and
libc.a.
-myellowknife- On embedded PowerPC systems, assume that the startup module is called
crt0.o and the standard C libraries are libyk.a and
libc.a.
-mvxworks- On System V.4 and embedded PowerPC systems, specify that you are
compiling for a VxWorks system.
-mwindiss- Specify that you are compiling for the WindISS simulation environment.
-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 embedded 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.
-mlongcall-mno-longcall- Default to making all function calls via pointers, so that functions
which reside further than 64 megabytes (67,108,864 bytes) from the
current location can be called. This setting can be overridden by the
shortcall function attribute, or by #pragma longcall(0).
Some linkers are capable of detecting out-of-range calls and generating
glue code on the fly. On these systems, long calls are unnecessary and
generate slower code. As of this writing, the AIX linker can do this,
as can the GNU linker for PowerPC/64. It is planned to add this feature
to the GNU linker for 32-bit PowerPC systems as well.
In the future, we may cause GCC to ignore all longcall specifications
when the linker is known to generate glue.
-pthread- Adds support for multithreading with the pthreads library.
This option sets flags for both the preprocessor and linker.