[bug] Using `determinant` with `-target cpu` and `target exe` results in undefined behavior and core dumps

[natevm]

Here's a little reproducer:

// compile with:
//      slangc -target exe -g -O0 testDeterminant.slang  -o testDeterminant &&./ testDeterminant
//      slangc -target cpp -g -O0 testDeterminant.slang  -o testDeterminant .cpp
export __extern_cpp int main(int argc, NativeString *argv)
{
    float3x3 test;
    test[0] = float3(42.f, 0.f, 0.f);
    test[1] = float3(0.f, 42.f, 0.f);
    test[2] = float3(0.f, 0.f, 42.f);

    float det = determinant(test);
    printf("Determinant is: %f\n", det);
    return 0;
}

With -target exe, the compiler throws a core dump:

gcc 13.3: /tmp/unknown-dRCsn9.cpp(26): warning :  #pragma once in main file
   26 | #pragma once
      |         ^~~~
gcc 13.3: /tmp/unknown-dRCsn9.cpp(2261): warning :  #pragma once in main file
 2261 | #pragma once
      |         ^~~~
gcc 13.3: /tmp/unknown-dRCsn9.cpp(10098): warning :  #pragma once in main file
10098 | #pragma once
      |         ^~~~
gcc 13.3: hlsl.meta.slang(8556): warning :  no return statement in function returning non-void [-Wreturn-type]
Illegal instruction (core dumped)

And when I look at the generated c++ code, the determinant is empty, doesn't return a float when it should, resulting in undefined behavior.

#line 10 "testDeterminant.slang"
struct Tuple_0
{
    float value0_0;
};


#line 8556 "hlsl.meta.slang"
static float determinant_0(Matrix<float, 3, 3>  m_0)
{

#line 8556
}


#line 3 "testDeterminant.slang"
int32_t main(int32_t argc_0, const char* * argv_0)
{
    Matrix<float, 3, 3>  test_0;
    Vector<float, 3>  _S1 = Vector<float, 3> (42.0f, 0.0f, 0.0f);

#line 6
    test_0[int(0)] = _S1;
    Vector<float, 3>  _S2 = Vector<float, 3> (0.0f, 42.0f, 0.0f);

#line 7
    test_0[int(1)] = _S2;
    Vector<float, 3>  _S3 = Vector<float, 3> (0.0f, 0.0f, 42.0f);

#line 8
    test_0[int(2)] = _S3;

    float det_0 = determinant_0(test_0);
    Tuple_0 _S4 = { det_0 };

#line 11
    printf("Determinant is: %f\n", det_0);
    return int(0);
}

with -target cuda, I seem to instead get a compilation error:

USER error: /printMain.slang(12): error 36107: entrypoint 'printMain' uses features that are not available in 'compute' stage for 'cuda' target.
void printMain(uint3 dispatchThreadID : SV_DispatchThreadID)
     ^~~~~~~~~
/user.slang(10): note: see using of 'determinant'
    float det = determinant(test);
                ^~~~~~~~~~~
hlsl.meta.slang(8556): note: see definition of 'determinant'
hlsl.meta.slang(8555): note: see declaration of 'require'
(0): error 39999: import of module 'printMain' failed because of a compilation error
(0): fatal error 39999: compilation ceased
abort compilation: (0): fatal error 39999: compilation ceased

[juliusikkala]

Looking at hlsl.meta.slang, it's clear that a default case is simply missing, there is no CPU implementation currently.

[natevm]

Seems like an easy enough thing to add. If I can find the time I can probably submit a PR.

[juliusikkala]

I did it already, will open PR shortly.