[SYCL] Add support for NVPTX device printf

Use `::printf` when not compiling for `__SPIR__`, this allows the use of
`EmitNVPTXDevicePrintfCallExpr` which packs the var args and dispatches
to CUDA's `vprintf`.

Fixes #1154

Author: jchlanda

clang/lib/CodeGen/CGGPUBuiltin.cpp

@@ -118,8 +118,19 @@ CodeGenFunction::EmitNVPTXDevicePrintfCallExpr(const CallExpr *E,
 
   // Invoke vprintf and return.
   llvm::Function* VprintfFunc = GetVprintfDeclaration(CGM.getModule());
-  return RValue::get(Builder.CreateCall(
-      VprintfFunc, {Args[0].getRValue(*this).getScalarVal(), BufferPtr}));
+  auto FormatSpecifier = Args[0].getRValue(*this).getScalarVal();
+  // Check if the format specifier is in the constant address space, vprintf is
+  // oblivious to address spaces, so it would have to be casted away.
+  if (Args[0]
+          .getRValue(*this)
+          .getScalarVal()
+          ->getType()
+          ->getPointerAddressSpace() == 4)
+    FormatSpecifier = Builder.CreateAddrSpaceCast(
+        FormatSpecifier, llvm::Type::getInt8PtrTy(Ctx));
+
+  return RValue::get(
+      Builder.CreateCall(VprintfFunc, {FormatSpecifier, BufferPtr}));
 }
 
 RValue

clang/lib/Sema/SemaSYCL.cpp

@@ -420,6 +420,8 @@ static bool IsSyclMathFunc(unsigned BuiltinID) {
 bool Sema::isKnownGoodSYCLDecl(const Decl *D) {
   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
     const IdentifierInfo *II = FD->getIdentifier();
+    if (FD->getBuiltinID() == Builtin::BIprintf)
+      return true;
     const DeclContext *DC = FD->getDeclContext();
     if (II && II->isStr("__spirv_ocl_printf") &&
         !FD->isDefined() &&

sycl/include/sycl/ext/oneapi/experimental/builtins.hpp

@@ -61,11 +61,11 @@ namespace experimental {
 //
 template <typename... Args>
 int printf(const __SYCL_CONSTANT_AS char *__format, Args... args) {
-#ifdef __SYCL_DEVICE_ONLY__
+#if defined(__SYCL_DEVICE_ONLY__) && defined(__SPIR__)
   return __spirv_ocl_printf(__format, args...);
 #else
   return ::printf(__format, args...);
-#endif
+#endif // defined(__SYCL_DEVICE_ONLY__) && defined(__SPIR__)
 }
 
 } // namespace experimental