[clang] [clang][SPIRV] Add builtin for OpGenericCastToPtrExplicit and its SPIR-V friendly binding (PR #137805)

[Victor Lomuller via cfe-commits]

================
@@ -35,8 +35,10 @@ static constexpr Builtin::Info BuiltinInfos[] = {
 static_assert(std::size(BuiltinInfos) == NumBuiltins);
 
 llvm::SmallVector<Builtin::InfosShard>
-SPIRVTargetInfo::getTargetBuiltins() const {
-  return {{&BuiltinStrings, BuiltinInfos}};
+BaseSPIRTargetInfo::getTargetBuiltins() const {
+  if (getTriple().isSPIRV())
+    return {{&BuiltinStrings, BuiltinInfos}};
----------------
Naghasan wrote:

> What if we had a BuiltinsSPIRVCore.td BuiltinsSPIRVVK.td and a BuiltinsSPIRVCL.td

I was looking into doing this.

> You won't have an unknown builtin if we do it this way because we would never expose the builtins that aren't valid for the target.

You will if you use a VK one when targeting `spirv64` rather than a clear message. But it is nitpicking and I only have a weak preference on the matter.

https://github.com/llvm/llvm-project/pull/137805