[WebAssembly] Initial support for reference type externref in clang

This patch introduces a new type __externref_t that denotes a WebAssembly opaque
reference type. It also implements builtin __builtin_wasm_ref_null_extern(),
that returns a null value of __externref_t. This lays the ground work
for further builtins and reference types.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D122215

1 files changed, 11 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index bb9a11e0..bb91b51 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -817,6 +817,17 @@ llvm::DIType *CGDebugInfo::CreateType(const BuiltinType *BT) {
       return DBuilder.createVectorType(/*Size=*/0, Align, ElemTy,
                                        SubscriptArray);
     }
+
+#define WASM_REF_TYPE(Name, MangledName, Id, SingletonId, AS)                  \
+  case BuiltinType::Id: {                                                      \
+    if (!SingletonId)                                                          \
+      SingletonId =                                                            \
+          DBuilder.createForwardDecl(llvm::dwarf::DW_TAG_structure_type,       \
+                                     MangledName, TheCU, TheCU->getFile(), 0); \
+    return SingletonId;                                                        \
+  }
+#include "clang/Basic/WebAssemblyReferenceTypes.def"
+
   case BuiltinType::UChar:
   case BuiltinType::Char_U:
     Encoding = llvm::dwarf::DW_ATE_unsigned_char;