diff options
Diffstat (limited to 'gcc/doc/tm.texi')
| -rw-r--r-- | gcc/doc/tm.texi | 29 |
1 files changed, 11 insertions, 18 deletions
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi index eb8a6189b95..98e6015e378 100644 --- a/gcc/doc/tm.texi +++ b/gcc/doc/tm.texi @@ -2013,23 +2013,16 @@ This section discusses the macros that describe which kinds of values (specifically, which machine modes) each register can hold, and how many consecutive registers are needed for a given mode. -@defmac HARD_REGNO_NREGS (@var{regno}, @var{mode}) -A C expression for the number of consecutive hard registers, starting +@deftypefn {Target Hook} {unsigned int} TARGET_HARD_REGNO_NREGS (unsigned int @var{regno}, machine_mode @var{mode}) +This hook returns the number of consecutive hard registers, starting at register number @var{regno}, required to hold a value of mode -@var{mode}. This macro must never return zero, even if a register +@var{mode}. This hook must never return zero, even if a register cannot hold the requested mode - indicate that with @code{TARGET_HARD_REGNO_MODE_OK} and/or @code{CANNOT_CHANGE_MODE_CLASS} instead. -On a machine where all registers are exactly one word, a suitable -definition of this macro is - -@smallexample -#define HARD_REGNO_NREGS(REGNO, MODE) \ - ((GET_MODE_SIZE (MODE) + UNITS_PER_WORD - 1) \ - / UNITS_PER_WORD) -@end smallexample -@end defmac +The default definition returns the number of words in @var{mode}. +@end deftypefn @defmac HARD_REGNO_NREGS_HAS_PADDING (@var{regno}, @var{mode}) A C expression that is nonzero if a value of mode @var{mode}, stored @@ -2037,7 +2030,7 @@ in memory, ends with padding that causes it to take up more space than in registers starting at register number @var{regno} (as determined by multiplying GCC's notion of the size of the register when containing this mode by the number of registers returned by -@code{HARD_REGNO_NREGS}). By default this is zero. +@code{TARGET_HARD_REGNO_NREGS}). By default this is zero. For example, if a floating-point value is stored in three 32-bit registers but takes up 128 bits in memory, then this would be @@ -2798,10 +2791,10 @@ pressure. A target hook returns the maximum number of consecutive registers of class @var{rclass} needed to hold a value of mode @var{mode}. -This is closely related to the macro @code{HARD_REGNO_NREGS}. In fact, -the value returned by @code{TARGET_CLASS_MAX_NREGS (@var{rclass}, +This is closely related to the macro @code{TARGET_HARD_REGNO_NREGS}. +In fact, the value returned by @code{TARGET_CLASS_MAX_NREGS (@var{rclass}, @var{mode})} target hook should be the maximum value of -@code{HARD_REGNO_NREGS (@var{regno}, @var{mode})} for all @var{regno} +@code{TARGET_HARD_REGNO_NREGS (@var{regno}, @var{mode})} for all @var{regno} values in the class @var{rclass}. This target hook helps control the handling of multiple-word values @@ -2815,9 +2808,9 @@ in words. A C expression for the maximum number of consecutive registers of class @var{class} needed to hold a value of mode @var{mode}. -This is closely related to the macro @code{HARD_REGNO_NREGS}. In fact, +This is closely related to the macro @code{TARGET_HARD_REGNO_NREGS}. In fact, the value of the macro @code{CLASS_MAX_NREGS (@var{class}, @var{mode})} -should be the maximum value of @code{HARD_REGNO_NREGS (@var{regno}, +should be the maximum value of @code{TARGET_HARD_REGNO_NREGS (@var{regno}, @var{mode})} for all @var{regno} values in the class @var{class}. This macro helps control the handling of multiple-word values |