[WebAssembly] Add new `export_name` clang attribute for controlling wasm export names

This is equivalent to the existing `import_name` and `import_module`
attributes which control the import names in the final wasm binary
produced by lld.

This maps the existing

This attribute currently requires a string rather than using the
symbol name for a couple of reasons:

1. Avoid confusion with static and dynamic linking which is
   based on symbol name.  Exporting a function from a wasm module using
   this directive is orthogonal to both static and dynamic linking.
2. Avoids name mangling.

Differential Revision: https://reviews.llvm.org/D70520

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 33e7b18..9fd4a5f 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -779,6 +779,12 @@ public:
         B.addAttribute("wasm-import-name", Attr->getImportName());
         Fn->addAttributes(llvm::AttributeList::FunctionIndex, B);
       }
+      if (const auto *Attr = FD->getAttr<WebAssemblyExportNameAttr>()) {
+        llvm::Function *Fn = cast<llvm::Function>(GV);
+        llvm::AttrBuilder B;
+        B.addAttribute("wasm-export-name", Attr->getExportName());
+        Fn->addAttributes(llvm::AttributeList::FunctionIndex, B);
+      }
     }
 
     if (auto *FD = dyn_cast_or_null<FunctionDecl>(D)) {