This change makes dumping and debugging work again with InstIds that are
now tagged with the CheckIRId. The textual representation of an InstId
is changed from `irN.instM` back to `instM` but the `M` is now a hex
value with the tag as part of it, which is the same number that is
physically in the `InstId::index` field. This prevents any cases where
we would potentially print incorrect values for large InstIds.
We teach the `dump` command in lldb to parse hex values for InstId so
that we can paste these numbers back into the debugger.
Use the `CheckIRId` as a unique identifier for the scope of an `InstId`
- if an `InstId` is created within the scope of one `CheckIRId` it must
not be used in the scope of a different `CheckIRId`.
This is achieved without extra storage, but with false negatives for
large inputs.
When an `InstId` is created, the original index of the `Inst` is XORed
with a tag derived from the `CheckIRId` to produce the final `InstId`.
When the `InstId` is used, the expected tag is XORed with the `InstId`
to get back to the original index - if the tags don't match, the
resulting index will be corrupted, likely too large - resulting in an
out of bounds index CHECK-failure.
(the tag value is derived as such:
* take the CheckIRId
* left shift one bit (padding zero)
* left shift another bit (padding 1 - used to signify that the resulting
`InstId` has a tag combined into it)
* reverse the bits
In this way, the tag is unlikely to overlap with the index for small
test cases - making it possible to separate out the `CheckIRId` from the
index in these cases to provide more meaningful debugging/CHECK
messages, and more informative `SemIR` textual dumping that can now
include the `CheckIRId` along with the `Inst`'s index in the name of an
`inst`)
The test churn here is improved printing as tagged `InstId`s can now,
with best effort (more likely for small test cases where the `CheckIRId`
and the `Inst` index aren't at risk of overlapping from the high and low
bits), render the `CheckIRId` as part of the inst's name. Going from
`instNN` to `irMM.instNN`.
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
The general strategy here is to force use of a thunk when we want to use
default arguments, and have Clang generate uses of the default arguments
on its side of the thunk.
To support this, change the key type used in `clang_decls` from being
just a `Decl*` to being a pair of `Decl*` and number of parameters in
the case of function decls. Import distinct `SemIR::Function`s for each
number of parameters that's used, and corresponding distinct thunks.
---------
Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
David Blaikie
Boaz Brickner
Dana Jansens
Jon Ross-Perkins
Ivana Ivanovska