Hans-Peter Nilsson <h...@axis.com> writes:
> Noticed while investigating a regression for cris-elf with
> r15-9239-g4d7a634f6d4102 "combine: Allow 2->2 combinations,
> but with a tweak [PR116398]" (to-be-reported).
>
> The comment was introduced when breaking out the
> combine_validate_cost function, in r0-59417-g64b8935d4809f3.
>
> I thought about wordsmithing to keep the "polarity" of the
> statement, but "are equal to or cheaper than" didn't read
> well.
>
> Ok to commit?
OK, thanks.
Richard
> -- >8 --
> The *code* has been the same since forever, but this
> comment, at a critical path, is misleading: if the new cost
> is the same (like, when doing an identity replacement), then
> combine_validate_cost returns true.
>
> * combine.cc (try_combine): Correct comment about
> combine_validate_cost.
> ---
> gcc/combine.cc | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/combine.cc b/gcc/combine.cc
> index 5f085187cfef..c2c1d50ca49f 100644
> --- a/gcc/combine.cc
> +++ b/gcc/combine.cc
> @@ -4129,8 +4129,8 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn *i1,
> rtx_insn *i0,
> }
> }
>
> - /* Only allow this combination if insn_cost reports that the
> - replacement instructions are cheaper than the originals. */
> + /* Reject this combination if insn_cost reports that the replacement
> + instructions are more expensive than the originals. */
> if (!combine_validate_cost (i0, i1, i2, i3, newpat, newi2pat, other_pat))
> {
> undo_all ();
