> Am 01.02.2024 um 23:46 schrieb Jakub Jelinek <ja...@redhat.com>:
>
> On Tue, Jan 30, 2024 at 07:33:10AM -0000, Roger Sayle wrote:
> + wide_int bits = wide_int::from (tree_nonzero_bits (rhs),
>
>
> + prec,
>
>
> + TYPE_SIGN (TREE_TYPE (rhs)));
>
>
> ...
>> + if (gimple_assign_rhs_code (stmt) == BIT_AND_EXPR
>> + && TREE_CODE (gimple_assign_rhs2 (stmt)) == INTEGER_CST
>> + && wi::to_wide (gimple_assign_rhs2 (stmt))
>> + == wi::mask (hprec, false, prec))
>
> This change broke bootstrap on aarch64-linux.
> The problem can be seen even on the reduced testcase.
>
> The IL on the unreduced testcase before widening_mul has:
> # val_583 = PHI <val_26(13), val_164(40)>
> ...
> pretmp_266 = MEM[(const struct wide_int_storage *)&D.160657].len;
> _264 = pretmp_266 & 65535;
> ...
> _176 = (sizetype) val_583;
> _439 = (sizetype) _264;
> _284 = _439 * 8;
> _115 = _176 + _284;
> where 583/266/264 have unsigned int type and 176/439/284/115 have sizetype.
> widening_mul first turns that into:
> # val_583 = PHI <val_26(13), val_164(40)>
> ...
> pretmp_266 = MEM[(const struct wide_int_storage *)&D.160657].len;
> _264 = pretmp_266 & 65535;
> ...
> _176 = (sizetype) val_583;
> _439 = (sizetype) _264;
> _284 = _264 w* 8;
> _115 = _176 + _284;
> and then is_widening_mult_rhs_p is called, with type sizetype (64-bit),
> rhs _264, hprec 32 and prec 64. Now tree_nonzero_bits (rhs) is
> 65535, so bits is 64-bit wide_int 65535, stmt is BIT_AND_EXPR,
> but we ICE on the
> wi::to_wide (gimple_assign_rhs2 (stmt)) == wi::mask (hprec, false, prec)
> comparison because wi::to_wide on gimple_assign_rhs2 (stmt) - unsigned int
> 65535 gives 32-bit wide_int 65535, while wi::mask (hprec, false, prec)
> gives 64-bit wide_int 0xffffffff and comparison between different precision
> wide_ints is forbidden.
>
> The following patch fixes it the same way how bits is computed earlier,
> by calling wide_int::from on the wi::to_wide (gimple_assign_rhs2 (stmt)),
> so we compare 64-bit 65535 with 64-bit 0xffffffff.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux plus tested on the
> testcase using cross to aarch64-linux, ok for trunk?
Ok
Richard
> 2024-02-01 Jakub Jelinek <ja...@redhat.com>
>
> PR middle-end/113705
> * tree-ssa-math-opts.cc (is_widening_mult_rhs_p): Use wide_int_from
> around wi::to_wide in order to compare value in prec precision.
>
> * g++.dg/opt/pr113705.C: New test.
>
> --- gcc/tree-ssa-math-opts.cc.jj 2024-02-01 09:14:16.623549514 +0100
> +++ gcc/tree-ssa-math-opts.cc 2024-02-01 17:48:59.151771177 +0100
> @@ -2572,7 +2572,8 @@ is_widening_mult_rhs_p (tree type, tree
> if (is_gimple_assign (stmt)
> && gimple_assign_rhs_code (stmt) == BIT_AND_EXPR
> && TREE_CODE (gimple_assign_rhs2 (stmt)) == INTEGER_CST
> - && wi::to_wide (gimple_assign_rhs2 (stmt))
> + && wide_int::from (wi::to_wide (gimple_assign_rhs2 (stmt)),
> + prec, TYPE_SIGN (TREE_TYPE (rhs)))
> == wi::mask (hprec, false, prec))
> *new_rhs_out = gimple_assign_rhs1 (stmt);
> else
> --- gcc/testsuite/g++.dg/opt/pr113705.C.jj 2024-02-01 19:02:29.181388575
> +0100
> +++ gcc/testsuite/g++.dg/opt/pr113705.C 2024-02-01 19:03:03.211918152 +0100
> @@ -0,0 +1,68 @@
> +// PR middle-end/113705
> +// { dg-do compile { target c++17 } }
> +// { dg-options "-O2 -w" }
> +
> +void foo ();
> +template <typename T> struct A : T { long bar () const; };
> +int a;
> +
> +template <typename T>
> +long
> +A<T>::bar () const
> +{
> + return this->baz ()[a];
> +}
> +
> +struct B {
> + struct { long b[1]; long c; } u;
> + unsigned d;
> + int e;
> + B (const B &);
> + ~B ();
> + const long *baz () const;
> + unsigned qux () const;
> +};
> +
> +B::B (const B &)
> +{
> + if (__builtin_expect (e, 0))
> + u.c = 0;
> +}
> +
> +B::~B ()
> +{
> + if (__builtin_expect (e, 0))
> + foo ();
> +}
> +
> +const long *
> +B::baz () const
> +{
> + return u.b;
> +}
> +
> +unsigned
> +B::qux () const
> +{
> + return d;
> +}
> +
> +struct C { A<B> corge () const; A<B> *f; };
> +
> +A<B>
> +C::corge () const
> +{
> + return f[1];
> +}
> +
> +void
> +test (C r, long *h, unsigned short *d)
> +{
> + for (int j = 0; j < 8; ++j)
> + {
> + A g = r.corge ();
> + *d = g.qux ();
> + for (unsigned i = 0; i < *d; ++i)
> + *h++ = g.bar ();
> + }
> +}
>
>
> Jakub
>
