pow of literal 0.0f not optimized away in some cases

Description
When using float pow(float x, float y) intrinsic, supplying 0.0f for x should return 0.0f. This fails in some cases.

Steps to Reproduce

// dxc -T ps_6_0 -E main

#define TEST 0
// TEST = 0,3 - fails to optimize away log+mul+exp
// TEST = 1,2,4 - optimizes to return 0.0f

float main() : SV_Target0
{
#if TEST == 0
    float x = 0.0f;
    return pow(x, 2.2f);
#elif TEST == 1
    const float x = 0.0f;
    return pow(x, 2.2f);
#elif TEST == 2
    float x = 0.0f;
    return pow(x, 2.0f);
#elif TEST == 3
    return pow(saturate(0.0f), 2.2f);
#else
    return pow(0.0f, 2.2f);
#endif
}

See repro in Compiler Explorer.

Actual Behavior
When TEST = 0,3 - fails to optimize away log+mul+exp.
When TEST = 1,2,4 - optimizes to return 0.0f (expected behavior for all cases).

Environment

• DXC version: 1.8.2403 and latest main
• Host Operating System: any

Reproduce the issue with the provided dxc command and HLSL example, comparing TEST values 0 through 4 and the generated output. Trace the pow intrinsic optimization or lowering path first; done means TEST=0 and TEST=3 also optimize to return 0.0f without the log, multiply, and exp sequence.