From fb54f550a047a40ff1438c5cfb890114baa31191 Mon Sep 17 00:00:00 2001 From: Segher Boessenkool Date: Mon, 12 Mar 2018 16:26:16 +0100 Subject: [PATCH] combine: Fix PR84780 (more LOG_LINKS trouble) There still are situations where we have stale LOG_LINKS. This causes combine to try two-insn combinations I2->I3 where the register set by I2 is used before I3 as well. Not good. This patch fixes it by checking for this situation in can_combine_p (similar to what we already do for three and four insn combinations). From-SVN: r258452 --- gcc/ChangeLog | 7 +++++++ gcc/combine.c | 1 + 2 files changed, 8 insertions(+) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 548de755bb7..cbdd4d2002a 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2018-03-12 Segher Boessenkool + + PR rtl-optimization/84169 + PR rtl-optimization/84780 + * combine.c (can_combine_p): Check for a 2-insn combination whether + the destination register is used between the two insns, too. + 2018-03-12 Richard Biener PR tree-optimization/84803 diff --git a/gcc/combine.c b/gcc/combine.c index c9105ed02b3..06a9ddde858 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -1990,6 +1990,7 @@ can_combine_p (rtx_insn *insn, rtx_insn *i3, rtx_insn *pred ATTRIBUTE_UNUSED, && (reg_used_between_p (dest, succ2, i3) || reg_used_between_p (dest, succ, succ2))) || (!succ2 && succ && reg_used_between_p (dest, succ, i3)) + || (!succ2 && !succ && reg_used_between_p (dest, insn, i3)) || (succ /* SUCC and SUCC2 can be split halves from a PARALLEL; in that case SUCC is not in the insn stream, so use SUCC2 -- 2.30.2