[PATCH] D125904: [Cuda] Use fallback method to mangle externalized decls if no CUID given

[Joseph Huber via Phabricator via cfe-commits]

jhuber6 created this revision.
jhuber6 added reviewers: yaxunl, tra.
Herald added subscribers: mattd, carlosgalvezp.
Herald added a project: All.
jhuber6 requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

CUDA requires that static variables be visible to the host when
offloading. However, The standard semantics of a stiatc variable dictate
that it should not be visible outside of the current file. In order to
access it from the host we need to perform "externalization" on the
static variable on the device. This requires generating a semi-unique
name that can be affixed to the variable as to not cause linker errors.

This is currently done using the CUID functionality, an MD5 hash value
set up by the clang driver. This allows us to achieve is mostly unique
ID that is unique even between multiple compilations of the same file.
However, this is not always availible. Instead, this patch uses the
unique ID from the file to generate a unique symbol name. This will
create a unique name that is consistent between the host and device side
compilations without requiring the CUID to be entered by the driver. The
one downside to this is that we are no longer stable under multiple
compilations of the same file. However, this is a very niche use-case
and is not supported by Nvidia's CUDA compiler so it likely to be good
enough.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D125904

Files:
  clang/lib/CodeGen/CGCUDANV.cpp
  clang/lib/CodeGen/CodeGenModule.cpp
  clang/test/CodeGenCUDA/device-fun-linkage.cu
  clang/test/CodeGenCUDA/static-device-var-rdc.cu

-------------- next part --------------
A non-text attachment was scrubbed...
Name: D125904.430422.patch
Type: text/x-patch
Size: 6377 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20220518/59e66898/attachment-0001.bin>