[WebAssembly] Add an import_module function attribute

This adds a C/C++ attribute which corresponds to the LLVM IR wasm-import-module
attribute. It allows code to specify an explicit import module.

Differential Revision: https://reviews.llvm.org/D57160

llvm-svn: 352106

1 files changed, 10 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index d36c5fbcd71..675838ed97f 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -760,6 +760,16 @@ public:
 
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
                            CodeGen::CodeGenModule &CGM) const override {
+    TargetCodeGenInfo::setTargetAttributes(D, GV, CGM);
+    if (const auto *FD = dyn_cast_or_null<FunctionDecl>(D)) {
+      if (const auto *Attr = FD->getAttr<WebAssemblyImportModuleAttr>()) {
+        llvm::Function *Fn = cast<llvm::Function>(GV);
+        llvm::AttrBuilder B;
+        B.addAttribute("wasm-import-module", Attr->getImportModuleName());
+        Fn->addAttributes(llvm::AttributeList::FunctionIndex, B);
+      }
+    }
+
     if (auto *FD = dyn_cast_or_null<FunctionDecl>(D)) {
       llvm::Function *Fn = cast<llvm::Function>(GV);
       if (!FD->doesThisDeclarationHaveABody() && !FD->hasPrototype())