[RISCV] Combine comparison and logic ops
Two comparison operations and a logical operation are combined into selection using MIN or MAX and comparison operation.
For optimization to be applied conditions have to be satisfied:
1. In comparison operations has to be the one common operand.
2. Supports only signed and unsigned integers.
3. Comparison has to be the same with respect to common operand.
4. There are no more users of comparison except logic operation.
5. Every combination of comparison and AND, OR are supported.
It will convert
%l0 = %a < %c
%l1 = %b < %c
%res = %l0 or %l1
into
%sel = min(%a, %b)
%res = %sel < %c
It supports several comparison operations (<, <=, >, >=), signed, unsigned values and different order of operands if they do not violate conditions.
Differential Revision: https://reviews.llvm.org/D134277