Revert "Turn on SPIR-V builtin generation for OpenCL CPP sources (#2466)" (#2508)

This reverts commit 80dfd864ae556369747074bbde8fc1d4c48547be.
The commit break Translator in cases when user supplied function is named
with the prefix which, after demangling, is the same as OpenCL builtin.
The culprit code is placed in during SPIRWriter OCL pass in
OCLToSPIRVBase::visitCallInst(CallInst &).
Failing name would be for example atomic_fetch_and_sub_uint32_explicit.

Original commit:
KhronosGroup/SPIRV-LLVM-Translator@9e60105170110e0

Author: bwlodarcz

llvm-spirv/lib/SPIRV/OCLToSPIRV.cpp

@@ -168,11 +168,9 @@ bool OCLToSPIRVBase::runOCLToSPIRV(Module &Module) {
   auto Src = getSPIRVSource(&Module);
   // This is a pre-processing pass, which transform LLVM IR module to a more
   // suitable form for the SPIR-V translation: it is specifically designed to
-  // handle OpenCL C/C++ and C++ for OpenCL modules and shouldn't be launched
-  // for other source languages.
-  if (std::get<0>(Src) != spv::SourceLanguageOpenCL_C &&
-      std::get<0>(Src) != spv::SourceLanguageOpenCL_CPP &&
-      std::get<0>(Src) != spv::SourceLanguageCPP_for_OpenCL)
+  // handle OpenCL C built-in functions and shouldn't be launched for other
+  // source languages
+  if (std::get<0>(Src) != spv::SourceLanguageOpenCL_C)
     return false;
 
   CLVer = std::get<1>(Src);

llvm-spirv/lib/SPIRV/OCLTypeToSPIRV.cpp

@@ -87,13 +87,7 @@ bool OCLTypeToSPIRVBase::runOCLTypeToSPIRV(Module &Module) {
   AdaptedTy.clear();
   WorkSet.clear();
   auto Src = getSPIRVSource(&Module);
-  // This is a pre-processing pass, which transform LLVM IR module to a more
-  // suitable form for the SPIR-V translation: it is specifically designed to
-  // handle OpenCL C/C++ and C++ for OpenCL types and shouldn't be launched for
-  // other source languages.
-  if (std::get<0>(Src) != spv::SourceLanguageOpenCL_C &&
-      std::get<0>(Src) != spv::SourceLanguageOpenCL_CPP &&
-      std::get<0>(Src) != spv::SourceLanguageCPP_for_OpenCL)
+  if (std::get<0>(Src) != spv::SourceLanguageOpenCL_C)
     return false;
 
   for (auto &F : Module.functions())

llvm-spirv/test/extensions/INTEL/SPV_INTEL_arbitrary_precision_fixed_point/capability-arbitrary-precision-fixed-point-numbers.ll

@@ -541,7 +541,7 @@ attributes #5 = { nounwind }
 
 !0 = !{i32 1, !"wchar_size", i32 4}
 !1 = !{i32 1, i32 2}
-!2 = !{i32 7, i32 100000}
+!2 = !{i32 4, i32 100000}
 !3 = !{!"clang version 11.0.0"}
 !4 = !{}
 !5 = !{!6, !6, i64 0}