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Diffstat (limited to 'gcc/doc/tm.texi')
| -rw-r--r-- | gcc/doc/tm.texi | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi index 716be18be40..bdd1dd3848f 100644 --- a/gcc/doc/tm.texi +++ b/gcc/doc/tm.texi @@ -2854,6 +2854,36 @@ as below: @end smallexample @end defmac +@deftypefn {Target Hook} {const reg_class_t *} TARGET_IRA_COVER_CLASSES (void) +Return an array of cover classes for the Integrated Register Allocator +(@acronym{IRA}). Cover classes are a set of non-intersecting register +classes covering all hard registers used for register allocation +purposes. If a move between two registers in the same cover class is +possible, it should be cheaper than a load or store of the registers. +The array is terminated by a @code{LIM_REG_CLASSES} element. + +The order of cover classes in the array is important. If two classes +have the same cost of usage for a pseudo, the class occurred first in +the array is chosen for the pseudo. + +This hook is called once at compiler startup, after the command-line +options have been processed. It is then re-examined by every call to +@code{target_reinit}. + +The default implementation returns @code{IRA_COVER_CLASSES}, if defined, +otherwise there is no default implementation. You must define either this +macro or @code{IRA_COVER_CLASSES} in order to use the integrated register +allocator with Chaitin-Briggs coloring. If the macro is not defined, +the only available coloring algorithm is Chow's priority coloring. + +This hook must not be modified from @code{NULL} to non-@code{NULL} or +vice versa by command-line option processing. +@end deftypefn + +@defmac IRA_COVER_CLASSES +See the documentation for @code{TARGET_IRA_COVER_CLASSES}. +@end defmac + @node Old Constraints @section Obsolete Macros for Defining Constraints @cindex defining constraints, obsolete method |