[SYCL] Don't emit @__cxa_pure_virtual into device code #16231
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This special symbol is used to handling calls to pure virtual functions in regular C++ program. However, for SYCL device code we do not have a guarantee that this symbol will be provided by SYCL backend compilers. Considering that pure virtual function call is an undefined behavior anyway, this PR replaces `@__cxa_pure_virtual` uses with `null` during SYCL device compilation to avoid issues with unresolved symbols.
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clang/lib/CodeGen/CGVTables.cpp
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| if (!PureVirtualFn) | ||
| PureVirtualFn = | ||
| getSpecialVirtualFn(CGM.getCXXABI().GetPureVirtualCallName()); | ||
| if (!PureVirtualFn) { |
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Should we just add this to getSpecialVirtualFn ?
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So, on the one hand, it would also cover deleted virtual functions. On the other hand, the attributes (in form of SYCL properties) for virtual functions that are callable from device cannot be applied to deleted virtual functions so it won't bring any extra benefit.
I think that the code looks cleaner if we move this change. Even though it is now a little bit more complicated to trace what are the special functions which we are ignoring for SYCL device code (because the filtering is within a helper lambda and not directly within an if pure virtual), the code overall seems cleaner to me anyway (less new { }).
Moved it in 6eeb45f
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I cancelled the latest pre-commit, because I had only changed comments in a test in the latest commit and previous commit had successfully passed pre-commit. I will proceed with merge |
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This special symbol is used to handling calls to pure virtual functions in regular C++ program. However, for SYCL device code we do not have a guarantee that this symbol will be provided by SYCL backend compilers.
Considering that pure virtual function call is an undefined behavior anyway, this PR replaces
@__cxa_pure_virtualuses withnullduring SYCL device compilation to avoid issues with unresolved symbols.