diff options
Diffstat (limited to 'gcc/doc/tm.texi')
| -rw-r--r-- | gcc/doc/tm.texi | 31 |
1 files changed, 18 insertions, 13 deletions
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi index acadc73667e..95cfd45617a 100644 --- a/gcc/doc/tm.texi +++ b/gcc/doc/tm.texi @@ -2774,6 +2774,17 @@ details. With LRA, the default is to use @var{mode} unmodified. @end deftypefn +@deftypefn {Target Hook} void TARGET_SELECT_EARLY_REMAT_MODES (sbitmap @var{modes}) +On some targets, certain modes cannot be held in registers around a +standard ABI call and are relatively expensive to spill to the stack. +The early rematerialization pass can help in such cases by aggressively +recomputing values after calls, so that they don't need to be spilled. + +This hook returns the set of such modes by setting the associated bits +in @var{modes}. The default implementation selects no modes, which has +the effect of disabling the early rematerialization pass. +@end deftypefn + @deftypefn {Target Hook} bool TARGET_CLASS_LIKELY_SPILLED_P (reg_class_t @var{rclass}) A target hook which returns @code{true} if pseudos that have been assigned to registers of class @var{rclass} would likely be spilled because @@ -4249,14 +4260,15 @@ must have move patterns for this mode. @deftypefn {Target Hook} opt_machine_mode TARGET_ARRAY_MODE (machine_mode @var{mode}, unsigned HOST_WIDE_INT @var{nelems}) Return the mode that GCC should use for an array that has @var{nelems} elements, with each element having mode @var{mode}. -Return @code{BLKmode} if an integer mode of the appropriate size should -be used; it is the caller's reponsibility to find such a mode. Usually the -search for the integer mode is limited to @code{MAX_FIXED_MODE_SIZE}, -but the @code{TARGET_ARRAY_MODE_SUPPORTED_P} hook allows a larger -mode to be used in specific cases. +Return no mode if the target has no special requirements. In the +latter case, GCC looks for an integer mode of the appropriate size +if available and uses BLKmode otherwise. Usually the search for the +integer mode is limited to @code{MAX_FIXED_MODE_SIZE}, but the +@code{TARGET_ARRAY_MODE_SUPPORTED_P} hook allows a larger mode to be +used in specific cases. The main use of this hook is to specify that an array of vectors should -also have a vector mode. The default implementation returns @code{BLKmode}. +also have a vector mode. The default implementation returns no mode. @end deftypefn @deftypefn {Target Hook} bool TARGET_ARRAY_MODE_SUPPORTED_P (machine_mode @var{mode}, unsigned HOST_WIDE_INT @var{nelems}) @@ -11861,13 +11873,6 @@ If defined, this function returns an appropriate alignment in bits for an atomic ISO C11 requires atomic compound assignments that may raise floating-point exceptions to raise exceptions corresponding to the arithmetic operation whose result was successfully stored in a compare-and-exchange sequence. This requires code equivalent to calls to @code{feholdexcept}, @code{feclearexcept} and @code{feupdateenv} to be generated at appropriate points in the compare-and-exchange sequence. This hook should set @code{*@var{hold}} to an expression equivalent to the call to @code{feholdexcept}, @code{*@var{clear}} to an expression equivalent to the call to @code{feclearexcept} and @code{*@var{update}} to an expression equivalent to the call to @code{feupdateenv}. The three expressions are @code{NULL_TREE} on entry to the hook and may be left as @code{NULL_TREE} if no code is required in a particular place. The default implementation leaves all three expressions as @code{NULL_TREE}. The @code{__atomic_feraiseexcept} function from @code{libatomic} may be of use as part of the code generated in @code{*@var{update}}. @end deftypefn -@deftypefn {Target Hook} bool TARGET_GATHER_SCATTER_SUPPORTS_SCALE_P (bool @var{gather_p}, unsigned int @var{offset_bitsize}, unsigned int @var{scale}) -Return true if it is possible to plant a gather load or scatter store, with -@var{gather_p} choosing between them. @var{offset_bitsize} if the size in bits -of the offset type and @var{scale} is the amount by which the offset is -multiplied. -@end deftypefn - @deftypefn {Target Hook} void TARGET_RECORD_OFFLOAD_SYMBOL (tree) Used when offloaded functions are seen in the compilation unit and no named sections are available. It is called once for each symbol that must be |