range-op: Fix up ABSU_EXPR handling [PR113756]

range-op: Fix up ABSU_EXPR handling [PR113756]

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.