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[libspirv][remangler] Don't remangle internal functions. #20148

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Sep 22, 2025
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[libspirv][remangler] Don't remangle internal functions. #20148

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3 changes: 3 additions & 0 deletions libclc/utils/libclc-remangler/LibclcRemangler.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -883,6 +883,9 @@ class LibCLCRemangler : public ASTConsumer {
}

bool remangleFunction(Function &Func, llvm::Module *M) {
if (Func.hasLocalLinkage())
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@wenju-he wenju-he Sep 22, 2025 •
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IIUC remangling is handling function parameter type and address space, but is unrelated to function linkage type.
I think the remangling process could be refined to skip functions like __clc_copysign whose parameter types don't need remangling.

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@Maetveis Maetveis Sep 22, 2025 •
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IIUC remangling is handling function parameter type and address space, but is unrelated to function linkage type.

Isn't the purpose of remangling that code compiled in SYCL (C++) language mode be able to call into libspirv functions which are compiled as OpenCL C, as there are differences between OpenCL and C++ with regards to e.g. long long size and char signedness?

If there's a function in libspirv that is internal linkage user code (the code we're linking libspirv into at user code compile time) shouldn't be calling it by definition. If it isn't being called by user code there can be no issues with C++ code looking for a different mangled name than what libspirv would provide.

I think the remangling process could be refined to skip functions like __clc_copysign whose parameter types don't need remangling.

The same problem could occur with functions that have types that need renaming.

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If there's a function in libspirv that is internal linkage user code (the code we're linking libspirv into at user code compile time) shouldn't be calling it by definition. If it isn't being called by user code there can be no issues with C++ code looking for a different mangled name than what libspirv would provide.

Right. It seems you're correct.

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I believe @Maetveis is right. The point of remangling is to give C++ code the opportunity to link against the OpenCL-C-based libclc, without there being signedness/size issues. Since functions with internal linkage shouldn't interface with C++ it should be fine to skip them during remangling.

return true;

if (!Func.getName().starts_with("_Z"))
return true;

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