On Wed, Oct 08, 2014 at 11:00:24PM +0800, Felix Yang wrote:
> The enclosed patch for 4.8 & 4.9 branch is a backport of r211885 from trunk.
>
> The only change is to use:
>
> for (def_rec = DF_INSN_INFO_DEFS (insn_info); *def_rec; def_rec++)
>
> other than the new FOR_EACH_INSN_INFO_DEF interface.
>
> Bootstrapped on x86_64-SUSE-Linux for both branches. OK to apply?
ChangeLog entry is missing, plus description why do you want to backport it.
If it fixes a bug on the branches, it would be better to have a bugzilla
PR for that, and definitely a testcase.
> --- gcc/loop-invariant.c (revision 216001)
> +++ gcc/loop-invariant.c (working copy)
> @@ -839,6 +839,41 @@ check_dependencies (rtx insn, bitmap depends_on)
> return true;
> }
>
> +/* Pre-check candidate DEST to skip the one which can not make a valid insn
> + during move_invariant_reg. SIMPLE is to skip HARD_REGISTER. */
> +
> +static bool
> +pre_check_invariant_p (bool simple, rtx dest)
> +{
> + if (simple && REG_P (dest) && DF_REG_DEF_COUNT (REGNO (dest)) > 1)
> + {
> + df_ref use;
> + rtx ref;
> + unsigned int i = REGNO (dest);
> + struct df_insn_info *insn_info;
> + df_ref *def_rec;
> +
> + for (use = DF_REG_USE_CHAIN (i); use; use = DF_REF_NEXT_REG (use))
> + {
> + ref = DF_REF_INSN (use);
> + insn_info = DF_INSN_INFO_GET (ref);
> +
> + for (def_rec = DF_INSN_INFO_DEFS (insn_info); *def_rec; def_rec++)
> + if (DF_REF_REGNO (*def_rec) == i)
> + {
> + /* Multi definitions at this stage, most likely are due to
> + instruction constraints, which requires both read and write
> + on the same register. Since move_invariant_reg is not
> + powerful enough to handle such cases, just ignore the INV
> + and leave the chance to others. */
> + return false;
> + }
> + }
> + }
> +
> + return true;
> +}
> +
> /* Finds invariant in INSN. ALWAYS_REACHED is true if the insn is always
> executed. ALWAYS_EXECUTED is true if the insn is always executed,
> unless the program ends due to a function call. */
> @@ -869,6 +904,7 @@ find_invariant_insn (rtx insn, bool always_reached
> simple = false;
>
> if (!may_assign_reg_p (SET_DEST (set))
> + || !pre_check_invariant_p (simple, dest)
> || !check_maybe_invariant (SET_SRC (set)))
> return;
>
>
> Cheers,
> Felix
Jakub
