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Re: [PATCH] Fix PR53501
> Well, it would rather be
>
> TYPE_UNSIGNED (type) == TYPE_UNSIGNED (TREE_TYPE (arg0))
> && TYPE_UNSIGNED (type) == TYPE_UNSIGNED (TREE_TYPE (arg1))
>
> but only in the !FLOAT_TYPE_P path.
That works in all cases I think, see existing cases in the folder.
> We could even compare
> TYPE_OVERFLOW_UNDEFINED I think. Or even just make sure
> that when TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (arg0)) also
> TYPE_OVERFLOW_UNDEFINED (type), thus
>
> !TYPE_OVERFLOW_UNDEFINED (type)
>
> || ((TREE_CODE (arg0) != MULT_EXPR
> ||
> || TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (arg0)))
>
> && (TREE_CODE (arg1) != MULT_EXPR
>
> || TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (arg1))))
>
> That is, the newly created multiplication in type TYPE should
> either not have undefined overflow or the inner multiplications
> all should already have. Best done with a comment in
> fold_plusminus_mult_expr.
I'm a little lost here. :-) I don't really care about the mainline at this
point, but the fix on the branches should be the minimal working one.
--
Eric Botcazou