[DirectX] Performing a `mul` between two double vectors produces invalid DXIL

Description
Performing a mul between two double vectors results in a DXIL validation error about the intrinsic call call double @dx.op.dot4.f64 being invalid.
Unlike the dot function which is expected to map directly to the dot DXIL op, the mul function should not be restricted to such a limitation.

Steps to Reproduce
https://hlsl.godbolt.org/z/asnerhMsd

Compile the following HLSL with -T cs_6_8

RWStructuredBuffer<double4> In;
RWStructuredBuffer<double> Out;

[numthreads(1, 1, 1)]
void main() {
    Out[0] = mul(In[0], In[1]);
}

Actual Behavior
Compiler output:

error: validation errors
<source>:6:14: error: DXIL intrinsic overload must be valid.
note: at '%14 = call double @dx.op.dot4.f64(i32 56, double %10, double %11, double %12, double %13, double %5, double %6, double %7, double %8)' in block '#0' of function 'main'.
Validation failed.


Compiler returned: 5

Environment

• DXC version 1.8.2505