[PATCH] D82317: [Clang/Test]: Update tests where `noundef` attribute is necessary

[Gui Andrade via Phabricator via cfe-commits]

guiand added a comment.

In D82317#2200789 <https://reviews.llvm.org/D82317#2200789>, @rjmccall wrote:

> Are you seriously adding an attribute to literally every argument and return value?  Why is this the right representation?

This adds an attribute to every argument and return value where the language rules denote it cannot be undef (which is ideally in most places, but definitely not everywhere). In a previous incarnation of this idea, the attribute was called `partialinit`, and had the inverse meaning -- the idea being that it would be a less invasive change because it is more common for these values to be fully defined (@rsmith at some point noted that in C, return values in general may be undef, which would complicate that a bit, but anyway was the idea). `partialinit` was scrapped as pretty much everybody agreed it wasn't ideal to have a negative attribute: the presence of `partialinit` meaning "proceed as normal", and its absence denoting a different behavior.

As for being an attribute, that was the level of granularity we had decided on. The alternative I suppose would be to some form of metadata.

As for being enabled by default, the idea was that transformation maintainers could get to using the attribute right away. This might be a good place to compromise.

And as for applying them to all the tests (rather than suppressing the attribute by default or something along those lines), we figured it would be best to keep the tests reflecting the actual common-case codegen. If `noundef` was on and showing up everywhere, the idea was to have the tests reflect that.


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https://reviews.llvm.org/D82317