[wasm] Fix decoding of shared global index space

test/mjsunit/wasm/globals.js

Index: test/mjsunit/wasm/globals.js
diff --git a/test/mjsunit/wasm/globals.js b/test/mjsunit/wasm/globals.js
index 4b976dcef2b6fb1a3bea52f6e4648d75684dcd61..ca421477a258f10f340d3414228f1a812123c848 100644
--- a/test/mjsunit/wasm/globals.js
+++ b/test/mjsunit/wasm/globals.js
@@ -64,3 +64,25 @@ function TestImportedExported(type, val, expected) {
 TestImportedExported(kAstI32, 415.5, 415);
 TestImportedExported(kAstF32, -979.34343, Math.fround(-979.34343));
 TestImportedExported(kAstF64, 81347.66666, 81347.66666);
+
+function TestGlobalIndexSpace(type, val) {
+  print("TestGlobalIndexSpace(" + val + ") = " + val);
+  var builder = new WasmModuleBuilder();
+  var im = builder.addImportedGlobal("foo", undefined, type);
+  assertEquals(0, im);
+  var def = builder.addGlobal(type, false);
+  assertEquals(1, def.index);
+  def.init_index = im;
+
+  var sig = makeSig([], [type]);
+  builder.addFunction("main", sig)
+    .addBody([kExprGetGlobal, def.index])
+    .exportAs("main");
+
+  var instance = builder.instantiate({foo: val});
+  assertEquals(val, instance.exports.main());
+}
+
+TestGlobalIndexSpace(kAstI32, 123);
+TestGlobalIndexSpace(kAstF32, 54321.125);
+TestGlobalIndexSpace(kAstF64, 12345.678);