Selects the IEEE rounding mode. Other Alpha compilers call this option
`-fprm 'rounding mode. The rounding mode can be one
of:
- `n'
-
Normal IEEE rounding mode. Floating point numbers are rounded towards
the nearest machine number or towards the even machine number in case
of a tie.
- `m'
-
Round towards minus infinity.
- `c'
-
Chopped rounding mode. Floating point numbers are rounded towards zero.
- `d'
-
Dynamic rounding mode. A field in the floating point control register
(fpcr, see Alpha architecture reference manual) controls the
rounding mode in effect. The C library initializes this register for
rounding towards plus infinity. Thus, unless your program modifies the
fpcr, `d' corresponds to round towards plus infinity.@end table
- `-mtrap-precision=trap precision'
-
In the Alpha architecture, floating point traps are imprecise. This
means without software assistance it is impossible to recover from a
floating trap and program execution normally needs to be terminated.
GNU CC can generate code that can assist operating system trap handlers
in determining the exact location that caused a floating point trap.
Depending on the requirements of an application, different levels of
precisions can be selected:
- `p'
-
Program precision. This option is the default and means a trap handler
can only identify which program caused a floating point exception.
- `f'
-
Function precision. The trap handler can determine the function that
caused a floating point exception.
- `i'
-
Instruction precision. The trap handler can determine the exact
instruction that caused a floating point exception.
Other Alpha compilers provide the equivalent options called
`-scope_safe' and `-resumption_safe'.
- `-mieee-conformant'
-
This option marks the generated code as IEEE conformant. You must not
use this option unless you also specify `-mtrap-precision=i' and either
`-mfp-trap-mode=su' or `-mfp-trap-mode=sui'. Its only effect
is to emit the line `.eflag 48' in the function prologue of the
generated assembly file. Under DEC Unix, this has the effect that
IEEE-conformant math library routines will be linked in.
- `-mbuild-constants'
-
Normally GNU CC examines a 32- or 64-bit integer constant to
see if it can construct it from smaller constants in two or three
instructions. If it cannot, it will output the constant as a literal and
generate code to load it from the data segment at runtime.
Use this option to require GNU CC to construct all integer constants
using code, even if it takes more instructions (the maximum is six).
You would typically use this option to build a shared library dynamic
loader. Itself a shared library, it must relocate itself in memory
before it can find the variables and constants in its own data segment.
- `-malpha-as'
-
- `-mgas'
-
Select whether to generate code to be assembled by the vendor-supplied
assembler (`-malpha-as') or by the GNU assembler `-mgas'.
- `-mbwx'
-
- `-mno-bwx'
-
- `-mcix'
-
- `-mno-cix'
-
- `-mmax'
-
- `-mno-max'
-
Indicate whether GNU CC should generate code to use the optional BWX,
CIX, and MAX instruction sets. The default is to use the instruction sets
supported by the CPU type specified via `-mcpu=' option or that
of the CPU on which GNU CC was built if none was specified.
- `-mcpu=cpu_type'
-
Set the instruction set, register set, and instruction scheduling
parameters for machine type cpu_type. You can specify either the
`EV' style name or the corresponding chip number. GNU CC
supports scheduling parameters for the EV4 and EV5 family of processors
and will choose the default values for the instruction set from
the processor you specify. If you do not specify a processor type,
GNU CC will default to the processor on which the compiler was built.
Supported values for cpu_type are
- `ev4'
-
- `21064'
-
Schedules as an EV4 and has no instruction set extensions.
- `ev5'
-
- `21164'
-
Schedules as an EV5 and has no instruction set extensions.
- `ev56'
-
- `21164a'
-
Schedules as an EV5 and supports the BWX extension.
- `pca56'
-
- `21164PC'
-
Schedules as an EV5 and supports the BWX and MAX extensions.
- `ev6'
-
- `21264'
-
Schedules as an EV5 (until Digital releases the scheduling parameters
for the EV6) and supports the BWX, CIX, and MAX extensions.
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