On Wed, 11 Sep 2019, Jakub Jelinek wrote:
> Hi!
>
> My recent change broke Linux kernel build, where we ICE in get_nonzero_bits
> which apparently assumes it must be called only on INTEGER_CSTs or
> SSA_NAMEs, while during generic folding it can be called say with PLUS_EXPR
> etc.
>
> tree_nonzero_bits apparently can be called on any tree code, as it has the
> return -1 fallback, but it doesn't really handle vector types, because it
> uses TYPE_PRECISION instead of element_precision.
> get_nonzero_bits also doesn't do anything useful for vector types,
> INTEGER_CSTs aren't vectors and vector type SSA_NAMEs won't really have
> range info (though, uses element_precision). In theory for VECTOR_CSTs we
> could or in get_nonzero_bits from all elements together or something
> similar, but still for SSA_NAMEs as we don't track anything it won't be
> useful, so this patch just punts on vector types if there is a widening
> conversion from signed. After all, a widening conversion for vectors
> wouldn't be really a conversion, but VEC_UNPACK_{LO,HI}_EXPR.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
Richard.
> 2019-09-11 Jakub Jelinek <ja...@redhat.com>
>
> PR middle-end/91725
> * match.pd ((A / (1 << B)) -> (A >> B)): Call tree_nonzero_bits instead
> of get_nonzero_bits, only call it for integral types.
>
> * gcc.c-torture/compile/pr91725.c: New test.
>
> --- gcc/match.pd.jj 2019-09-10 10:13:29.723000308 +0200
> +++ gcc/match.pd 2019-09-10 20:14:06.164054126 +0200
> @@ -325,9 +325,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> && (TYPE_UNSIGNED (TREE_TYPE (@1))
> || (element_precision (type)
> == element_precision (TREE_TYPE (@1)))
> - || (get_nonzero_bits (@0)
> - & wi::mask (element_precision (TREE_TYPE (@1)) - 1, true,
> - element_precision (type))) == 0))))
> + || (INTEGRAL_TYPE_P (type)
> + && (tree_nonzero_bits (@0)
> + & wi::mask (element_precision (TREE_TYPE (@1)) - 1,
> + true,
> + element_precision (type))) == 0)))))
> (rshift @0 @2)))
>
> /* Preserve explicit divisions by 0: the C++ front-end wants to detect
> --- gcc/testsuite/gcc.c-torture/compile/pr91725.c.jj 2019-09-10
> 20:09:39.499987576 +0200
> +++ gcc/testsuite/gcc.c-torture/compile/pr91725.c 2019-09-10
> 20:08:21.302141038 +0200
> @@ -0,0 +1,7 @@
> +/* PR middle-end/91725 */
> +
> +unsigned long long
> +foo (unsigned long long x, unsigned long long y, int z)
> +{
> + return (x + y) / (1 << z);
> +}
>
> Jakub
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 247165 (AG München)
