This patch makes the final major change of the RemoveDIs project, changing the
default IR output from debug intrinsics to debug records. This is expected to
break a large number of tests: every single one that tests for uses or
declarations of debug intrinsics and does not explicitly disable writing
records.
If this patch has broken your downstream tests (or upstream tests on a
configuration I wasn't able to run):
1. If you need to immediately unblock a build, pass
`--write-experimental-debuginfo=false` to LLVM's option processing for all
failing tests (remember to use `-mllvm` for clang/flang to forward arguments to
LLVM).
2. For most test failures, the changes are trivial and mechanical, enough that
they can be done by script; see the migration guide for a guide on how to do
this: https://llvm.org/docs/RemoveDIsDebugInfo.html#test-updates
3. If any tests fail for reasons other than FileCheck check lines that need
updating, such as assertion failures, that is most likely a real bug with this
patch and should be reported as such.
For more information, see the recent PSA:
https://discourse.llvm.org/t/psa-ir-output-changing-from-debug-intrinsics-to-debug-records/79578
Metadata (via ValueAsMetadata) can reference constant expressions
that may no longer be supported. These references can both be in
function-local metadata and module metadata, if the same expression
is used in multiple functions. At least in theory, such references
could also be in metadata proper, rather than just inside
ValueAsMetadata references in calls.
Instead of trying to expand these expressions (which we can't
reliably do), pretend that the constant has been deleted, which
means that ValueAsMetadata references will get replaced with
undef metadata.
Fixes https://github.com/llvm/llvm-project/issues/68281.
This fixes the bitcode upgrade failure reported in
https://reviews.llvm.org/D155924#4616789.
The expansion always happens in the entry block, so this may be
inaccurate if there are trapping constant expressions.
