A DXC optimization is producing i25 type, but shouldn't for DXIL

[tex3d]

Description
An llvm optimization (like some switch optimization) is resulting in odd-sized int value types, such as i25. We should not produce integer values of odd sizes like this.

A separate but related issue for catching this class of problem in DxilValidation is #6563.

Steps to Reproduce

uint param;

bool fn()
{
    switch (param)
    {
    case 0:
    case 20:
    case 24:
        return false;
    }
    return true;
}

float4 main() : SV_Target
{
    float4 ret = float4(0, 0, 0, 0);
    if (fn())
    {
        ret = float4(1, 1, 1, 1);
    }
    return ret;
}

Actual Behavior
Results in IR containing i25:

  %6 = trunc i32 %3 to i25
  %7 = lshr i25 15728638, %6
  %8 = and i25 %7, 1
  %9 = icmp ne i25 %8, 0
  %10 = select i1 %9, float 1.000000e+00, float 0.000000e+00

This i25 type should never be produced during compilation or optimization.

Environment

• DXC version: latest main, not a regression
• Host Operating System: any