[clang] [clang][CodeGen] Fix metadata when vectorization is disabled by pragma (PR #135163)

[Ryotaro Kasuga via cfe-commits]

kasuga-fj wrote:

Ping.

I think there are two possible interpretations of `vectorize(disable) vectorize_width(scalable)`, as follows:

- It is equivalent to `vectorize(disable)` so vectorization is disabled, as the document says:
  > Pragmas setting transformation options imply the transformation is enabled, as if it was enabled via the corresponding transformation pragma (e.g. `vectorize(enable)`). If the transformation is disabled (e.g. `vectorize(disable)`), that takes precedence over transformations option pragmas implying that transformation..
- Since `vectorize(disable)` is equivalent to `vectorize_width(1)`, it is equivalent to `vectorize_width(1, scalable)` so that vectorization should be performed [as previously commented](https://github.com/llvm/llvm-project/pull/135163#discussion_r2037236948).

I think we should clarify which one is correct (alternatively, it may be possible to reject it on the frontend). I would appreciate any thoughts on this.


https://github.com/llvm/llvm-project/pull/135163