[SPIR-V] Add macro definition when -fdeclare-spirv-builtins is activated

Define __SPIRV_BUILTIN_DECLARATIONS__ when passing
-fdeclare-spirv-builtins to clang.

Signed-off-by: Victor Lomuller <[email protected]>

Author: Naghasan

clang/lib/Frontend/InitPreprocessor.cpp

@@ -467,6 +467,10 @@ static void InitializeStandardPredefinedMacros(const TargetInfo &TI,
       Builder.defineMacro("CL_SYCL_LANGUAGE_VERSION", "121");
   }
 
+  if (LangOpts.DeclareSPIRVBuiltins) {
+    Builder.defineMacro("__SPIRV_BUILTIN_DECLARATIONS__");
+  }
+
   // Not "standard" per se, but available even with the -undef flag.
   if (LangOpts.AsmPreprocessor)
     Builder.defineMacro("__ASSEMBLER__");

clang/test/Preprocessor/spirv-macro.cpp

@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 %s -E -dM | FileCheck %s
+// RUN: %clang_cc1 %s  -fdeclare-spirv-builtins  -E -dM | FileCheck --check-prefix=CHECK-SPIRV %s
+
+// CHECK-NOT:#define __SPIRV_BUILTIN_DECLARATIONS__
+
+// CHECK-SPIRV:#define __SPIRV_BUILTIN_DECLARATIONS__