FIRST_PSEUDO_REGISTER
FIRST_PSEUDO_REGISTER-1
; thus, the first
pseudo register's number really is assigned the number
FIRST_PSEUDO_REGISTER
.
FIXED_REGISTERS
This information is expressed as a sequence of numbers, separated by commas and surrounded by braces. The nth number is 1 if register n is fixed, 0 otherwise.
The table initialized from this macro, and the table initialized by
the following one, may be overridden at run time either automatically,
by the actions of the macro CONDITIONAL_REGISTER_USAGE
, or by
the user with the command options `-ffixed-reg
',
`-fcall-used-reg
' and `-fcall-saved-reg
'.
CALL_USED_REGISTERS
FIXED_REGISTERS
but has 1 for each register that is
clobbered (in general) by function calls as well as for fixed
registers. This macro therefore identifies the registers that are not
available for general allocation of values that must live across
function calls.
If a register has 0 in CALL_USED_REGISTERS
, the compiler
automatically saves it on function entry and restores it on function
exit, if the register is used within the function.
CONDITIONAL_REGISTER_USAGE
fixed_regs
and call_used_regs
(both of type char []
) after they have been initialized from the two preceding macros.
This is necessary in case the fixed or call-clobbered registers depend on target flags.
You need not define this macro if it has no work to do.
If the usage of an entire class of registers depends on the target
flags, you may indicate this to GCC by using this macro to modify
fixed_regs
and call_used_regs
to 1 for each of the
registers in the classes which should not be used by GCC. Also define
the macro REG_CLASS_FROM_LETTER
to return NO_REGS
if it
is called with a letter for a class that shouldn't be used.
(However, if this class is not included in GENERAL_REGS
and all
of the insn patterns whose constraints permit this class are
controlled by target switches, then GCC will automatically avoid using
these registers when the target switches are opposed to them.)
NON_SAVING_SETJMP
setjmp
and related functions fail to save the registers, or that
longjmp
fails to restore them. To compensate, the compiler
avoids putting variables in registers in functions that use
setjmp
.
INCOMING_REGNO (out)
OUTGOING_REGNO (in)