On Mon, Dec 19, 2011 at 10:39 PM, Richard Sandiford
<rdsandif...@googlemail.com> wrote:
> The recent(ish) improvements to widening multiplication support have
> disabled madd and msub for fixed-point types. The problem is that the
> optab is now chosen based on:
>
> optype = build_nonstandard_integer_type (from_mode, from_unsigned1);
>
> which is specific to integer types.
>
> The only time optype differs from type1 is when we've switched to using
> unsigned types, possibly with a wider mode. As written, the handling of
> mixed signedness really is only suitable for integer types, so this patch
> enforces that and makes the call above conditional on it. It also fixes
> the first argument to be the precision rather than the mode.
>
> (As the argument mismatch proved, the precision doesn't actually
> matter here; only the signedness does. I think an equivalent fix
> would be to call:
>
> optype = unsigned_type_for (type1);
>
> That ought to work for fixed point types too, but is a little less
> obvious and a little less future-proof. Since the rest of the block
> hasn't been adapted to fixed point types, it didn't seem worth the
> confusion.)
>
> Tested on mips-sde-elf, where it fixes gcc.target/mips/dpaq_sa_l_w.c
> and gcc.target/mips/dpsq_sa_l_w.c. OK to install?
Ok with ...
> Richard
>
>
> gcc/
> * tree-ssa-math-opts.c (convert_plusminus_to_widen): Restrict
> handling of signedness differences to integer types. Only build
> a new optype if type1 isn't correct.
>
> Index: gcc/tree-ssa-math-opts.c
> ===================================================================
> --- gcc/tree-ssa-math-opts.c 2011-12-19 21:18:43.000000000 +0000
> +++ gcc/tree-ssa-math-opts.c 2011-12-19 21:23:12.000000000 +0000
> @@ -2304,10 +2304,13 @@ convert_plusminus_to_widen (gimple_stmt_
> from_mode = TYPE_MODE (type1);
> from_unsigned1 = TYPE_UNSIGNED (type1);
> from_unsigned2 = TYPE_UNSIGNED (type2);
> + optype = type1;
>
> /* There's no such thing as a mixed sign madd yet, so use a wider mode. */
> if (from_unsigned1 != from_unsigned2)
> {
> + if (TREE_CODE (type) != INTEGER_TYPE)
> + return false;
using INTEGRAL_TYPE_P (type) instead. That way it still works
when applied to enum type multiplications.
Thanks,
Richard.
> /* We can use a signed multiply with unsigned types as long as
> there is a wider mode to use, or it is the smaller of the two
> types that is unsigned. Note that type1 >= type2, always. */
> @@ -2322,6 +2325,8 @@ convert_plusminus_to_widen (gimple_stmt_
> }
>
> from_unsigned1 = from_unsigned2 = false;
> + optype = build_nonstandard_integer_type (GET_MODE_PRECISION
> (from_mode),
> + false);
> }
>
> /* If there was a conversion between the multiply and addition
> @@ -2355,7 +2360,6 @@ convert_plusminus_to_widen (gimple_stmt_
> /* Verify that the machine can perform a widening multiply
> accumulate in this mode/signedness combination, otherwise
> this transformation is likely to pessimize code. */
> - optype = build_nonstandard_integer_type (from_mode, from_unsigned1);
> this_optab = optab_for_tree_code (wmult_code, optype, optab_default);
> handler = find_widening_optab_handler_and_mode (this_optab, to_mode,
> from_mode, 0, &actual_mode);
