Merge pull request #460 from Vsevolod-Livinskij/master

Fix for issue #453

run_tests.py

@@ -60,6 +60,11 @@ if not is_windows:
 else:
     ispc_exe = "../Release/ispc.exe"
 
+# checks the required ispc compiler otherwise prints an error message
+if not os.path.exists(ispc_exe):
+    sys.stderr.write("Fatal error: missing ispc compiler: %s\n" % ispc_exe)
+    sys.exit()
+
 ispc_exe += " " + options.ispc_flags
 
 print ispc_exe