From e091a0fe0779f788ee11e81f0d3d6f5d7bd0e9f4 Mon Sep 17 00:00:00 2001 From: Segher Boessenkool Date: Tue, 21 Mar 2017 00:08:16 +0100 Subject: [PATCH] combine: Fix 79910 If the dest of an I0 or I1 is used in an insn before I2, as can happen in various uncommon cases, and we manage to do the combination, the set is moved to I2, which is wrong. Don't allow combining the insns in this case. PR rtl-optimization/79910 * combine.c (can_combine_p): Do not allow combining an I0 or I1 if its dest is used by an insn before I2 (other than the combined insns themselves, which are properly handled already). From-SVN: r246297 --- gcc/ChangeLog | 7 +++++++ gcc/combine.c | 4 ++++ 2 files changed, 11 insertions(+) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 55e9bc81e58..afb4a523472 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2017-03-20 Segher Boessenkool + + PR rtl-optimization/79910 + * combine.c (can_combine_p): Do not allow combining an I0 or I1 + if its dest is used by an insn before I2 (other than the combined + insns themselves, which are properly handled already). + 2017-03-20 Segher Boessenkool Revert: diff --git a/gcc/combine.c b/gcc/combine.c index 66215a607bd..17258f0e0c5 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -1953,6 +1953,10 @@ can_combine_p (rtx_insn *insn, rtx_insn *i3, rtx_insn *pred ATTRIBUTE_UNUSED, || (succ2 && FIND_REG_INC_NOTE (succ2, dest)) /* Don't substitute into a non-local goto, this confuses CFG. */ || (JUMP_P (i3) && find_reg_note (i3, REG_NON_LOCAL_GOTO, NULL_RTX)) + /* Make sure that DEST is not used after INSN but before SUCC, or + between SUCC and SUCC2. */ + || (succ && reg_used_between_p (dest, insn, succ)) + || (succ2 && reg_used_between_p (dest, succ, succ2)) /* Make sure that DEST is not used after SUCC but before I3. */ || (!all_adjacent && ((succ2 -- 2.30.2