[WebAssembly] Add codegen support for the import_field attribute

This adds the LLVM side of https://reviews.llvm.org/D57602 -- the
import_field attribute. See that patch for details.

Differential Revision: https://reviews.llvm.org/D57603

llvm-svn: 352931
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
index f1bb524..c102439 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
@@ -114,9 +114,16 @@
           F.hasFnAttribute("wasm-import-module")) {
         StringRef Name =
             F.getFnAttribute("wasm-import-module").getValueAsString();
-        Sym->setModuleName(Name);
+        Sym->setImportModule(Name);
         getTargetStreamer()->emitImportModule(Sym, Name);
       }
+      if (TM.getTargetTriple().isOSBinFormatWasm() &&
+          F.hasFnAttribute("wasm-import-name")) {
+        StringRef Name =
+            F.getFnAttribute("wasm-import-name").getValueAsString();
+        Sym->setImportName(Name);
+        getTargetStreamer()->emitImportName(Sym, Name);
+      }
     }
   }