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range-op: Fix up ABSU_EXPR handling [PR113756]

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ABSU_EXPR unary expr is special because it has a signed integer
argument and unsigned integer result (of the same precision).

The following testcase is miscompiled since ABSU_EXPR handling has
been added to range-op because it uses widest_int::from with the
result sign (i.e. UNSIGNED) rather than the operand sign (i.e. SIGNED),
so e.g. for the 32-bit int argument mask ends up 0xffffffc1 or something
similar and even when it has most significant bit in the precision set,
in widest_int (tree-ssa-ccp.cc really should stop using widest_int, but
that is I think stage1 task) it doesn't appear to be negative and so
bit_value_unop ABSU_EXPR doesn't set the resulting mask/value from
oring of the argument and its negation.

Fixed thusly, not doing that for GIMPLE_BINARY_RHS because I don't know
about a binary op that would need something similar.

2024-02-06  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/113756
	* range-op.cc (update_known_bitmask): For GIMPLE_UNARY_RHS,
	use TYPE_SIGN (lh.type ()) instead of sign for widest_int::from
	of lh_bits value and mask.

	* gcc.dg/pr113756.c: New test.
This commit is contained in:
Jakub Jelinek 2024-02-07 10:59:06 +01:00
parent 6e308d5f71
commit 29998cc8a2
2 changed files with 40 additions and 2 deletions
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6
gcc/range-op.cc
View file

@ -435,8 +435,10 @@ update_known_bitmask (irange &r, tree_code code,
bit_value_unop (code, sign, prec, &widest_value, &widest_mask,
TYPE_SIGN (lh.type ()),
TYPE_PRECISION (lh.type ()),
widest_int::from (lh_bits.value (), sign),
widest_int::from (lh_bits.mask (), sign));
widest_int::from (lh_bits.value (),
TYPE_SIGN (lh.type ())),
widest_int::from (lh_bits.mask (),
TYPE_SIGN (lh.type ())));
break;
case GIMPLE_BINARY_RHS:
bit_value_binop (code, sign, prec, &widest_value, &widest_mask,

36
gcc/testsuite/gcc.dg/pr113756.c Normal file
View file

@ -0,0 +1,36 @@
/* PR tree-optimization/113756 */
/* { dg-do run { target int32plus } } */
/* { dg-options "-O2" } */
int d, e, i, k, l = -8;
signed char h, j;
int
bar (int n, int o, int p3)
{
int a = o - p3, b = n - p3, c = a + b, f = -b, g = c < 0 ? -c : c;
return a <= f && a <= g ? o : p3;
}
void
foo (int *n, unsigned short o)
{
unsigned p = 8896;
for (; e >= 0; e--)
p = 5377;
for (; h <= 0; h++)
for (; j <= 0; j++)
{
*n = 1611581749;
i = bar (34, p - 5294, *n - 1611581687);
k = i + p + 65535 + o + *n - 1611718251;
if (k != 0)
__builtin_abort ();
}
}
int
main ()
{
foo (&l, l);
}