[HLSL] Scalar to vector implicit conversion

[llvm-beanz]

While HLSL doesn't allow vector extension as an implicit conversion it does allow scalar to vector conversion as an implicit conversion.

void fn(int i) {}

void fn(vector<int64_t, 2> v) {}

export void call(int i, int64_t l, vector<int,2> vi, vector<int64_t, 2> vl) {
  fn(i);  // calls fn(int)
  fn(l);  // calls fn(vector<int64_t,2>)
  fn(vi); // calls fn(vector<int64_t,2>)
  fn(vl); // calls fn(vector<int64_t,2>)
}

Compiler Explorer

We need to update the language specification and implement the scalar->vector implicit conversion.

Depends on microsoft/hlsl-specs#232.

Acceptance Criteria

• Updated HLSL specification for scalar splat conversion
• Tests verifying correct overload resolution of the case described above.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Chris B (llvm-beanz)

While HLSL doesn't allow vector extension as an implicit conversion it does allow scalar to vector conversion as an implicit conversion.

void fn(int i) {}

void fn(vector<int64_t, 2> v) {}

export void call(int i, int64_t l, vector<int,2> vi, vector<int64_t, 2> vl) {
  fn(i);  // calls fn(int)
  fn(l);  // calls fn(vector<int64_t,2>)
  fn(vi); // calls fn(vector<int64_t,2>)
  fn(vl); // calls fn(vector<int64_t,2>)
}

Compiler Explorer

We need to update the language specification and implement the scalar->vector implicit conversion.

Depends on microsoft/hlsl-specs#232.

Acceptance Criteria

• Updated HLSL specification for scalar splat conversion
• Tests verifying correct overload resolution of the case described above.