The initial two cases require a SCEVConstant as RHS. Pull up the condition
to check and swap SCEVConstants from below. Also remove a redundant
check & swap if RHS is SCEVUnknown.

This is a cleanup of the only llvm-prefer-isa-or-dyn-cast-in-conditionals finding in the clangd code base. This patch was created by automatically applying the fixes from clang-tidy.

Differential Revision: https://reviews.llvm.org/D113899

Add the codegen for fir.constc.

This patch is part of the upstreaming effort from fir-dev.

Differential Revision: https://reviews.llvm.org/D114063

Co-authored-by: Eric Schweitz <eschweitz@nvidia.com>
Co-authored-by: Jean Perier <jperier@nvidia.com>

Previously, in case there was only one `Optional` operand/result within
the list, we would always return `None` from the accessor, e.g., for a
single optional result we would generate:

```
return self.operation.results[0] if len(self.operation.results) > 1 else None
```

But what we really want is to return `None` only if the length of
`results` is smaller than the total number of element groups (i.e.,
the optional operand/result is in fact missing).

This commit also renames a few local variables in the generator to make
the distinction between `isVariadic()` and `isVariableLength()` a bit
more clear.

Reviewed By: ftynse

Differential Revision: https://reviews.llvm.org/D113855

`BufferizableOpInterface::bufferize` will only be called on ops that
have tensor operands and/or results.

Differential Revision: https://reviews.llvm.org/D113962