f78 MIPS Options Contents|Index|Previous|Next

MIPS options

The following ‘-m’ options are defined for the MIPS family of computers.

-mcpu=cpu type

Assume the defaults for the machine type

cpu

type

when scheduling instructions. The choices for

cpu

type

are ‘

r2000

’, ‘

r3000

’, ‘

r4000

’, ‘

r4400

, ‘

r4600

’, and ‘

r6000

’. While picking a specific

cpu

type

will schedule things appropriately for that particular chip, the compiler will not generate any code that does not meet level 1 of the MIPS ISA (instruction set architecture) without the ‘

-mips2

’ or ‘

-mips3

’ switches being used.

-mips1

Issue instructions from level 1 of the MIPS ISA. This is the default. ‘

r3000

’ is the default

cpu

type

at this ISA level.

-mips2

Issue instructions from level 2 of the MIPS ISA (branch likely ffb , square root instructions). ‘

r6000

’ is the default CPU type at this ISA level.

-mips3

Issue instructions from level 3 of the MIPS ISA (64 bit instructions).

r4000

is the default

cpu type

at this ISA level. This option does not change the sizes of any of the C data types.

-mips4

Issue instructions from level 4 of the MIPS ISA.

r8000

is the default

cpu type

at this ISA level.

-mfp32

Assume that 32 32-bit floating point registers are available. This is the default.

-mfp64

Assume that 32 64-bit floating point registers are available. This is the default when the

-mips3

option is used.

-mgp32

Assume that 32 32-bit general purpose registers are available. This is the default.

-mgp64

Assume that 32 64-bit general purpose registers are available. This is the default when the

-mips3

option is used.

-mint64

Types

long

int

, and

pointer

are 64 bits. This works only if

-mips3

is also specified.

-mlong64

Types

long

and

pointer

are 64 bits, and type

int

is 32 bits. This works only if

-mips3

is also specified.

-mabi=32

-mabi=n32

-mabi=64

-mabi=eabi

Generate code for the indicated ABI.

-mmips-as

Generate code for the MIPS assembler, and invoke

mips-tfile

to add normal debug information. This is the default for all platforms except for the OSF/1 reference platform, using the OSF/rose object format. If the either of the

-gstabs

-gstabs+

switches are used, the

mips-tfile

program will encapsulate the

stabs

within MIPS ECOFF.

-mgas

Generate code for the GNU assembler. This is the default on the OSF/1 reference platform, using the

OSF/rose object

format.

-msplit-addresses

-mno-split-addresses

Generate code to load the high and low parts of address constants separately.

This allows

gcc

to optimize away redundant loads of the high order bits of addresses. This optimization requires GNU

and GNU

. This optimization is enabled by default for some embedded targets where GNU

and GNU

are standard.

-mrnames

-mno-rnames

The

-mrnames

switch says to output code using the MIPS software names for the registers, instead of the hardware names (i.e.,

instead of

). The only known assembler that supports this option is the Algorithmics assembler.

-mgpopt

-mno-gpopt

The

-mgpopt

switch says to write all of the data declarations before the instructions in the text section, this allows the MIPS assembler to generate one word memory references instead of using two words for short global or static data items. This is on by default if optimization is selected.

-mstats

-mno-stats

For each non-inline function processed, the

-mstats

switch causes the compiler to emit one line to the standard error file to print statistics about the program (number of registers saved, stack size, etc.).

-mmemcpy

-mno-memcpy

The

-mmemcpy

switch makes all block moves call the appropriate string function (

memcpy

bcopy

) instead of possibly generating inline code.

-mmips-tfile

-mno-mips-tfile

The

-mno-mips-tfile

switch causes the compiler not post-process the object file with the

mips-tfile

program, after the MIPS assembler has generated it to add debug support. If

mips-tfile

is not run, then no local variables will be available to the debugger. In addition,

stage2

and

stage3

objects will have the temporary filenames passed to the assembler embedded in the object file, which means the objects will not compare the same. The

-mno-mips-tfile

switch should only be used when there are bugs in the

mips-tfile

program that prevents compilation.

-msoft-float

Generate output containing library calls for floating point.

Warning:

The requisite libraries are not part of GNU CC. Normally the facilities of the machine’s usual C compiler are used, but this can’t be done directly in cross-compilation. You must make your own arrangements to provide suitable library functions for cross-compilation.

-mhard-float

Generate output containing floating point instructions. This is the default if you use the unmodified sources.

-mabicalls

-mno-abicalls

Emit (or do not emit) the pseudo operations .

abicalls

, .

cpload

, and .

cprestore

that some System V.4 ports use for position independent code.

-mlong-calls

-mno-long-calls

Do all calls with the

JALR

instruction, which requires loading up a function’s address into a register before the call. You need to use this switch, if you call outside of the current 512 megabyte segment to functions that are not through pointers.

-mhalf-pic

-mno-half-pic

Put pointers to extern references into the data section and load them up, rather than put the references in the text section.

-membedded-pic

-mno-embedded-pic

Generate PIC code suitable for some embedded systems. All calls are made using PC relative address, and all data is addressed using the

$gp

and GNU

which do most of the work.

-membedded-data

-mno-embedded-data

Allocate variables to the read-only data section first if possible, then next in the small data section if possible, otherwise in data. This gives slightly slower code th ffb an the default, but reduces the amount of RAM required when executing, and thus may be preferred for some embedded systems.

-msingle-float

-mdouble-float

The

-msingle-float

switch tells

gcc

to assume that the floating point coprocessor only supports single precision operations, as on the

r4650

chip. The

-mdouble-float

switch permits

gcc

to use double precision operations. This is the default.

-mmad

-mno-mad

Permit use of the

mad

madu

and

mul

instructions, as on the

r4650

chip.

-m4650

Turns on

-msingle-float

-mmad

, and, at least for now,

-mcpu=r4650

-EL

Compile code for the processor in little endian mode. The requisite libraries are assumed to exist.

-EB

Compile code for the processor in big endian mode. The requisite libraries are assumed to exist.

-G num

Put global and static items less than or equal to

num

bytes into the

small data

bss

sections instead of the

normal data

bss

section. This allows the assembler to emit one word memory reference instructions based on the global pointer (

$28

), instead of the normal two words used. By default,

num

is 8 when the MIPS assembler is used, and 0 when the GNU assembler is used. The ‘

-G num

’ switch is also passed to the assembler and linker. All modules should be compiled with the same ‘

-G num

’

value.

-nocpp

Tell the MIPS assembler to not run its preprocessor over user assembler files (with a suffix, ‘

’) when assembling them.

These options are defined by the macro, TARGET_SWITCHES, in the machine description. The default for the options is also defined by that macro, enabling you to change the defaults. 0