From b412ce8e961052e6becea3bc783a53e1d5feaa0f Mon Sep 17 00:00:00 2001 From: Segher Boessenkool <segher@kernel.crashing.org> Date: Sat, 17 Apr 2021 18:06:17 +0000 Subject: [PATCH] combine: Don't create REG_UNUSED notes if the reg already died (PR99927) If the register named in an existing REG_UNUSED note dies somewhere between where the note used to be and I3, we should just drop it. 2021-04-21 Segher Boessenkool <segher@kernel.crashing.org> PR rtl-optimization/99927 * combine.c (distribute_notes) [REG_UNUSED]: If the register already is dead, just drop it. --- gcc/combine.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/gcc/combine.c b/gcc/combine.c index 9063a07bd009..62bf4aeaabae 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -14366,6 +14366,11 @@ distribute_notes (rtx notes, rtx_insn *from_insn, rtx_insn *i3, rtx_insn *i2, we keep notes from i2 or i1 if they will turn into REG_DEAD notes. */ + /* If this register is set or clobbered between FROM_INSN and I3, + we should not create a note for it. */ + if (reg_set_between_p (XEXP (note, 0), from_insn, i3)) + break; + /* If this register is set or clobbered in I3, put the note there unless there is one already. */ if (reg_set_p (XEXP (note, 0), PATTERN (i3))) -- GitLab