[PATCH] D113273: [fir] TargetRewrite: Rewrite COMPLEX values

[Jean Perier via Phabricator via llvm-commits]

jeanPerier added a comment.

> The IR you posted is confusing because it contains both complex<f32> and fir.complex<4>. Are both valid, or are we moving away from one of them?

Yes they are both valid types, but are not exactly the same thing. `complex<f32>` is the mlir complex type that is used to represent C++ std::complex types, while `fir.complex<4>` represents Fortran complex type. The nuance is subtle but essential because C++ std::complex and Fortran complex type (same as C99 complex) may not be compatible in function interface [*], so we want to keep them as distinct types in function signatures.

It is OK to cast a `fir.ref<complex<f32>>` to a `fir.ref<fir.complex<4>` because std::complex and Fortran complex are memory layout compatible (since std::complex guarantees this with the C99 complex type).

[X] For instance Fortran complex and std::complex are not returned the same way on X86 32 bits.


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https://reviews.llvm.org/D113273