https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91957
--- Comment #3 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> --- Author: rsandifo Date: Wed Oct 2 07:37:10 2019 New Revision: 276440 URL: https://gcc.gnu.org/viewcvs?rev=276440&root=gcc&view=rev Log: [LRA] Don't make eliminable registers live (PR91957) One effect of https://gcc.gnu.org/ml/gcc-patches/2019-09/msg00802.html was to strengthen the sanity check in lra_assigns so that it checks whether reg_renumber is consistent with the whole conflict set. This duly tripped on csky for a pseudo that had been allocated to the eliminated frame pointer. (csky doesn't have a separate hard frame pointer.) lra-lives uses: /* Set of hard regs (except eliminable ones) currently live. */ static HARD_REG_SET hard_regs_live; to track the set of live directly-referenced hard registers, and it correctly implements the exclusion when setting up the initial set: hard_regs_live &= ~eliminable_regset; But later calls to make_hard_regno_live and make_hard_regno_dead would process eliminable registers like other registers, recording conflicts for them and potentially making them live. (Note that after r266086, make_hard_regno_dead adds conflicts for registers that are already marked dead.) I think this would have had the effect of pessimising targets without a separate hard frame pointer. 2019-10-02 Richard Sandiford <richard.sandif...@arm.com> gcc/ PR middle-end/91957 * lra-lives.c (make_hard_regno_dead): Don't record conflicts for eliminable registers. (make_hard_regno_live): Likewise, and don't make them live. Modified: trunk/gcc/ChangeLog trunk/gcc/lra-lives.c
