Summary:
We use this `dyn_ptr` argument in Clang/OpenMP to handle the
`KernelLaunchEnvironment`. This is a per-kernel argument used to share
some information. Currenetly, it's prepended to the argument list and we
generate storage for it in the runtime.
This is bad for a few reasons:
1. It changes the ABI by shifting user arguments
2. It cannot be trivially be left uninitialized if unused
3. The runtime must allocate its own memory for it
This PR changes it to be appended instead. Additionally, space for this
is always emitted. This means the OMPIRBuilder itself will provide the
storage, we simply need to populate it in the runtime if it is used.
This means that if it's unused we don't always pay the cost and it's
easier for non-OpenMP users to ignore it.
Backward compatibility is maintained by auto-upgrading the kernel
arguments. In `libomptarget` we completely allocate a new buffer to
store this in the new format. The plugins still need to respect the old
ABI of the called device object, so we simply rotate it if it's the old
version.
Use the DataLayout-aware TargetFolder instead of ConstantFolder in
Clang's CGBuilder. The primary impact of this change is that GEP
constant expressions are now emitted in canonical `getelementptr i8`
form. This is in preparation for the migration to ptradd, which requires
this form.
Part of the test updates were performed by Claude Code and reviewed by
me.
This reverts commit 047db150c66e245e9df7db178b893ce6b29820f5.
The original version of the commit caused assertion failures in DSE.
Those were fixed in ec059d81aafedb253a02d6f490ad9b9747611038, so trying
to reland this again.
This helps to clean up any dead stores that come up at the end of the
destructor. The motivating example was a refactoring in libc++'s
basic_string implementation in 8dae17be2991cd7f0d7fd9aa5aecd064520a14f6
that added a zeroing store into the destructor, causing a large
performance regression on an internal workload. We also saw a ~0.2%
performance increase on an internal server workload when enabling this.
I also tested this against all of the non-flaky tests in our large C++
codebase and found a minimal number of issues that all happened to be in
user code.
Added codegen for scope directive, enabled allocate and firstprivate
clauses, and added scope directive LIT test.
Testing
- LIT tests (including new scope test).
- OpenMP scope example test from 5.2 OpenMP API examples document.
- Three executable scope tests from OpenMP_VV/sollve_vv suite.
