Remove double negation in VN

[EgorBo]

A couple of diffs from copying this optimization from global morph to VN

runtime/src/coreclr/jit/morph.cpp

Lines 8131 to 8139 in 79bc254

	// Remove double negation/not.
	if (op1->OperIs(oper))
	{
	JITDUMP("Remove double negation/not\n")
	GenTree* op1op1 = op1->gtGetOp1();
	DEBUG_DESTROY_NODE(tree);
	DEBUG_DESTROY_NODE(op1);
	return op1op1;
	}

[Copilot]

Pull request overview

This pull request adds a double negation/not removal optimization to the Value Numbering (VN) phase of the JIT compiler. The optimization removes redundant consecutive NOT or NEG operations (e.g., NOT(NOT(x)) → x, NEG(NEG(x)) → x), matching similar logic already implemented in the global morph phase.

Changes:

• Added double negation removal optimization for VNF_NOT and VNF_NEG operations in VNForFunc

[AndyAyersMS]

I had some similar VN things in #88527 including using De Morgan's laws to push NOT down in boolean VN "trees" ... feel free to poach or ignore.