Fix regression that broke asm.js validation in #139 (since 2016-03-24. Fixes emscripten-core/emscripten#4307.

Author: juj

lib/Target/JSBackend/CallHandlers.h

@@ -1438,7 +1438,7 @@ DEF_BUILTIN_HANDLER(emscripten_bool8x16_anyTrue, SIMD_Bool8x16_anyTrue);
 DEF_BUILTIN_HANDLER(emscripten_bool8x16_allTrue, SIMD_Bool8x16_allTrue);
 
 DEF_CALL_HANDLER(emscripten_atomic_fence, {
-  if (EnablePthreads) return "Atomics_add(HEAP32, 0, 0) /* fence */";
+  if (EnablePthreads) return "(Atomics_add(HEAP32, 0, 0)|0) /* fence */";
   else return "/* fence */";
 })
 

lib/Target/JSBackend/JSBackend.cpp

@@ -2728,7 +2728,7 @@ void JSWriter::generateExpression(const User *I, raw_string_ostream& Code) {
     break;
   }
   case Instruction::Fence:
-    if (EnablePthreads) Code << "Atomics_add(HEAP32, 0, 0) /* fence */";
+    if (EnablePthreads) Code << "(Atomics_add(HEAP32, 0, 0)|0) /* fence */";
     else Code << "/* fence */";
     break;
   }