Enoki does not generate fma instruction for fmadd with Array<float, 1> and Clang

[robinchrist]

Working example here:
https://godbolt.org/z/rPbr91Gfb

Consider the following code:

#include <enoki/array.h>

template<class VecT>
void fma_foo(
    void* x,
    void* y,
    void* z,
    void* target
) {
    VecT res = enoki::fmadd(enoki::load<VecT>(x), enoki::load<VecT>(y), enoki::load<VecT>(z));

    enoki::store(target, res);
}

The following two instantiations work as expected:

//Correct
template
void fma_foo<float>(
    void* x,
    void* y,
    void* z,
    void* target
);

//Correct
template
void fma_foo<enoki::Array<float, 8>>(
    void* x,
    void* y,
    void* z,
    void* target
);

and generate a vfmadd132.. instruction

This one does not:

//Uh Oh
template
void fma_foo<enoki::Array<float, 1>>(
    void* x,
    void* y,
    void* z,
    void* target
);

instead of fma, it generates

vmulss  xmm0, xmm0, dword ptr [rsi]
vaddss  xmm0, xmm0, dword ptr [rdx]

This issue is present on all versions of Clang (9+), but does not seem to exist with GCC

Can you fix this on your side or should I file a bug with Clang?