[WebAssembly] Fix getSymbolValue for exported globals

The code wasn't previously taking into account that the
global index space is not same as the into in the Globals
array since the latter does not include imported globals.

This fixes the WebAssembly waterfall failures.

Differential Revision: https://reviews.llvm.org/D37384

llvm-svn: 312340

llvm/lib/Object/WasmObjectFile.cpp

@@ -788,7 +788,7 @@ uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
     return Exports[Sym.ElementIndex].Index;
   case WasmSymbol::SymbolType::GLOBAL_EXPORT: {
-    uint32_t GlobalIndex = Exports[Sym.ElementIndex].Index;
+    uint32_t GlobalIndex = Exports[Sym.ElementIndex].Index - NumImportedGlobals;
     assert(GlobalIndex < Globals.size());
     const wasm::WasmGlobal& Global = Globals[GlobalIndex];
     return Global.InitExpr.Value.Int32;