[Bug tree-optimization/31178] VRP can infer a range for b in a >> b and a << b

[vincent-gcc at vinc17 dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=31178

--- Comment #19 from Vincent Lefèvre <vincent-gcc at vinc17 dot net> ---
(In reply to rguenther@suse.de from comment #18)
> Sure, if that's what the precision is used for.  The message from Andrew
> sounded like 'I want the precision for the shift operand but let me
> just use that of the shifted anyway'

Andrew should clarify. From what I understand, he does not want the precision
for the shift operand (right operand), but an upper bound (this is what this
bug is about). And this upper bound is deduced from the precision of the
shifted element (promoted left operand).