https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98782
--- Comment #39 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Sandiford <rsand...@gcc.gnu.org>: https://gcc.gnu.org/g:01f3e6a40e7202310abbeb41c345d325bd69554f commit r12-6415-g01f3e6a40e7202310abbeb41c345d325bd69554f Author: Richard Sandiford <richard.sandif...@arm.com> Date: Mon Jan 10 14:47:08 2022 +0000 ira: Consider modelling caller-save allocations as loop spills If an allocno A in an inner loop L spans a call, a parent allocno AP can choose to handle a call-clobbered/caller-saved hard register R in one of two ways: (1) save R before each call in L and restore R after each call (2) spill R to memory throughout L (2) can be cheaper than (1) in some cases, particularly if L does not reference A. Before the patch we always did (1). The patch adds support for picking (2) instead, when it seems cheaper. It builds on the earlier support for not propagating conflicts to parent allocnos. gcc/ PR rtl-optimization/98782 * ira-int.h (ira_caller_save_cost): New function. (ira_caller_save_loop_spill_p): Likewise. * ira-build.c (ira_propagate_hard_reg_costs): Test whether it is cheaper to spill a call-clobbered register throughout a loop rather than spill it around each individual call. If so, treat all call-clobbered registers as conflicts and... (propagate_allocno_info): ...do not propagate call information from the child to the parent. * ira-color.c (move_spill_restore): Update accordingly. * ira-costs.c (ira_tune_allocno_costs): Use ira_caller_save_cost. gcc/testsuite/ * gcc.target/aarch64/reg-alloc-3.c: New test.
