[WebAssembly] Add V128 value type to binary format

Summary: Adds the necessary support to lib/ObjectYAML and fixes SIMD
calls to allow the tests to work. Also removes some dead code that
would otherwise have to have been updated.

Reviewers: aheejin, dschuff, sbc100

Subscribers: jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D52105

llvm-svn: 342689
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
index db4fb5c..c55308b 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
@@ -149,6 +149,8 @@
     return wasm::ValType::F32;
   if (RC == &WebAssembly::F64RegClass)
     return wasm::ValType::F64;
+  if (RC == &WebAssembly::V128RegClass)
+    return wasm::ValType::V128;
   llvm_unreachable("Unexpected register class");
 }