[Bounds checks] Tighten pRange in MergeEdgeAssertions via X != CNS assertions

[EgorBo]

Closes #121259

When we already have, say, [1..10] range for X and we encounter X != 1 assertion, we can tighten the range to [2..10]

Removes bounds checks for the following snippet:

void Test(ReadOnlySpan<char> name)
{
    if (name is [] or [':'] or [':', not ':', ..])
    {
        Console.WriteLine("test");
    }    
}

Diffs

[Copilot]

Pull Request Overview

This pull request enhances the JIT's range check optimization by adding logic to handle not-equal (!=) assertions. The change allows the optimizer to tighten ranges when it encounters assertions of the form var != cnstLimit by checking if the current range boundaries match the limit value and adjusting them accordingly.

• Replaces simple skip behavior for != assertions with range tightening logic
• When var != 100 and range is [100, X], tightens to [101, X]
• When var != 100 and range is [Y, 100], tightens to [Y, 99]

[EgorBo]

PTAL @dotnet/jit-contrib a small change to improve bounds checks

[EgorBo]

/ba-g deadletter. (And runtime-coreclr hardware-intrinsics being worked on - #121145 (comment))