[clang] [llvm] [CodeGen][i386] Move -mregparm storage earlier and fix Runtime calls (PR #89707)

[Eli Friedman via cfe-commits]

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@@ -4781,6 +4782,7 @@ CodeGenModule::CreateRuntimeFunction(llvm::FunctionType *FTy, StringRef Name,
         }
       }
       setDSOLocal(F);
+      markRegisterParameterAttributes(F);
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efriedma-quic wrote:

Suggested text on the clang change:

FIXME: We should use CodeGenModule::SetLLVMFunctionAttributes() instead of trying to approximate the attributes using the LLVM function signature.  This requires revising the API of CreateRuntimeFunction().

https://github.com/llvm/llvm-project/pull/89707