From 1bcb4c4faa4bd6b1c917c75b100d618faf9e628c Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Wed, 2 Oct 2019 07:37:10 +0000 Subject: [PATCH] [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 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. From-SVN: r276440 --- gcc/ChangeLog | 7 +++++++ gcc/lra-lives.c | 6 +++++- 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index b3a42ae4ef2..69f5d7153c9 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2019-10-02 Richard Sandiford + + 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. + 2019-10-01 David Malcolm * diagnostic-show-locus.c (layout::print_gap_in_line_numbering): diff --git a/gcc/lra-lives.c b/gcc/lra-lives.c index 389a79d701d..1d1525ca2e5 100644 --- a/gcc/lra-lives.c +++ b/gcc/lra-lives.c @@ -281,7 +281,8 @@ static void make_hard_regno_live (int regno) { lra_assert (HARD_REGISTER_NUM_P (regno)); - if (TEST_HARD_REG_BIT (hard_regs_live, regno)) + if (TEST_HARD_REG_BIT (hard_regs_live, regno) + || TEST_HARD_REG_BIT (eliminable_regset, regno)) return; SET_HARD_REG_BIT (hard_regs_live, regno); sparseset_set_bit (start_living, regno); @@ -295,6 +296,9 @@ make_hard_regno_live (int regno) static void make_hard_regno_dead (int regno) { + if (TEST_HARD_REG_BIT (eliminable_regset, regno)) + return; + lra_assert (HARD_REGISTER_NUM_P (regno)); unsigned int i; EXECUTE_IF_SET_IN_SPARSESET (pseudos_live, i)