ira: Add ira_subloop_allocnos_can_differ_p
color_pass has two instances of the same code for propagating non-cap
assignments from parent loops to subloops. This patch adds a helper
function for testing when such propagations are required for correctness
and uses it to remove the duplicated code.
A later patch will use this in ira-build.c too, which is why the
function is exported to ira-int.h.
No functional change intended.
gcc/
PR rtl-optimization/98782
* ira-int.h (ira_subloop_allocnos_can_differ_p): New function,
extracted from...
* ira-color.c (color_pass): ...here.