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?
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
