[Bug tree-optimization/105374] [12 Regression] ICE in fold_convert_loc, at fold-const.cc:2580 during GIMPLE pass: reassoc since r12-7338-g884f77b4222289510e1df9db2889b60c5df6fcda

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105374

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #2)
> This can (and IMHO should no matter what) be fixed in reassoc by:
> --- gcc/tree-ssa-reassoc.cc.jj	2022-04-14 13:46:59.690140053 +0200
> +++ gcc/tree-ssa-reassoc.cc	2022-04-25 15:34:03.811473537 +0200
> @@ -2254,7 +2254,11 @@ eliminate_redundant_comparison (enum tre
>  	 BIT_AND_EXPR or BIT_IOR_EXPR was of a wider integer type,
>  	 we need to convert.  */
>        if (!useless_type_conversion_p (TREE_TYPE (curr->op), TREE_TYPE (t)))
> -	t = fold_convert (TREE_TYPE (curr->op), t);
> +	{
> +	  if (!fold_convertible_p (TREE_TYPE (curr->op), t))
> +	    continue;
> +	  t = fold_convert (TREE_TYPE (curr->op), t);
> +	}

Note for vectors the "appropriate" way to make a value from a bool is

  bool ? -1 : 0

though I guess the question is whether we know if we want a vector true (-1)
or a scalar true (1) here ...

>  
>        if (TREE_CODE (t) != INTEGER_CST
>  	  && !operand_equal_p (t, curr->op, 0))
> 
> But another question is if we shouldn't actually optimize it rather than
> punting out.

Ideally yes.

> The reason why that happens is that while eliminate_redundant_comparison
> indirectly passes the V4BImode vector type as TYPE argument, the function
> doesn't actually use it and uses truth_type (V4SImode) instead.
> truth_type use has been introduced in r0-119133-gae22ac3c62db451bae
> but at that point the type argument didn't exist.
> That has been only introduced in r10-3154-g5f487a349de62613d7fa429 .
> I wonder if we can't just kill the truth_type computation and replace all
> uses with type...

I guess so - but does that fix anything here?