diff --git a/emcc b/emcc
index 621cb340a7e87..e02854bdb231f 100755
--- a/emcc
+++ b/emcc
@@ -1973,6 +1973,11 @@ try:
       if debug_level >= 4:
         generate_source_map(target)
       shutil.move(final, js_target)
+      # TODO: use an async blob, which would allow code rewriting on the client:
+      #   var blob = new Blob([codeString]);
+      #   var script = document.createElement('script');
+      #   script.src = URL.createObjectURL(blob);
+      #   document.body.appendChild(script);
       script_tag = '''<script async type="text/javascript" src="%s"></script>''' % base_js_target
       html.write(shell.replace('{{{ SCRIPT }}}', script_tag))
     else:
diff --git a/src/jsifier.js b/src/jsifier.js
index 58dc46532e1f8..d533e36b76058 100644
--- a/src/jsifier.js
+++ b/src/jsifier.js
@@ -18,7 +18,7 @@ var INDENTATION = ' ';
 var functionStubSigs = {};
 
 // JSifier
-function JSify(data, functionsOnly, givenFunctions) {
+function JSify(data, functionsOnly) {
   //B.start('jsifier');
   var mainPass = !functionsOnly;
 
@@ -109,7 +109,7 @@ function JSify(data, functionsOnly, givenFunctions) {
       dprint('unparsedFunctions','====================\n// Processing function batch of ' + currBaseLineNums.length +
                                  ' functions, ' + currFuncLines.length + ' lines, functions left: ' + data.unparsedFunctions.length);
       if (DEBUG_MEMORY) MemoryDebugger.tick('pre-func');
-      JSify(analyzer(intertyper(currFuncLines, true, currBaseLineNums), true), true, Functions);
+      JSify(analyzer(intertyper(currFuncLines, true, currBaseLineNums), true), true);
       if (DEBUG_MEMORY) MemoryDebugger.tick('post-func');
     }
     currFuncLines = currBaseLineNums = null; // Do not hold on to anything from inside that loop (JS function scoping..)
@@ -1796,7 +1796,7 @@ function JSify(data, functionsOnly, givenFunctions) {
           }
         });
       }
-      JSify(globalsData, true, Functions);
+      JSify(globalsData, true);
       globalsData = null;
       data.unparsedGlobalss = null;
 
diff --git a/src/library_browser.js b/src/library_browser.js
index b368c6ac8ba1d..e0f53052d1639 100644
--- a/src/library_browser.js
+++ b/src/library_browser.js
@@ -478,19 +478,30 @@ mergeInto(LibraryManager.library, {
         // in the coordinates.
         var rect = Module["canvas"].getBoundingClientRect();
         var x, y;
+        
+        // Neither .scrollX or .pageXOffset are defined in a spec, but
+        // we prefer .scrollX because it is currently in a spec draft.
+        // (see: http://www.w3.org/TR/2013/WD-cssom-view-20131217/)
+        var scrollX = ((typeof window.scrollX !== 'undefined') ? window.scrollX : window.pageXOffset);
+        var scrollY = ((typeof window.scrollY !== 'undefined') ? window.scrollY : window.pageYOffset);
+#if ASSERTIONS
+        // If this assert lands, it's likely because the browser doesn't support scrollX or pageXOffset
+        // and we have no viable fallback.
+        assert((typeof scrollX !== 'undefined') && (typeof scrollY !== 'undefined'), 'Unable to retrieve scroll position, mouse positions likely broken.');
+#endif
         if (event.type == 'touchstart' ||
             event.type == 'touchend' ||
             event.type == 'touchmove') {
           var t = event.touches.item(0);
           if (t) {
-            x = t.pageX - (window.scrollX + rect.left);
-            y = t.pageY - (window.scrollY + rect.top);
+            x = t.pageX - (scrollX + rect.left);
+            y = t.pageY - (scrollY + rect.top);
           } else {
             return;
           }
         } else {
-          x = event.pageX - (window.scrollX + rect.left);
-          y = event.pageY - (window.scrollY + rect.top);
+          x = event.pageX - (scrollX + rect.left);
+          y = event.pageY - (scrollY + rect.top);
         }
 
         // the canvas might be CSS-scaled compared to its backbuffer;
diff --git a/src/library_sdl.js b/src/library_sdl.js
index 1c1e8107cb819..fc38dd1ca48ca 100644
--- a/src/library_sdl.js
+++ b/src/library_sdl.js
@@ -1059,11 +1059,35 @@ var LibrarySDL = {
       var src = buffer >> 2;
       var dst = 0;
       var isScreen = surf == SDL.screen;
-      var data32 = new Uint32Array(data.buffer);
-      var num = data32.length;
-      while (dst < num) {
-        // HEAP32[src++] is an optimization. Instead, we could do {{{ makeGetValue('buffer', 'dst', 'i32') }}};
-        data32[dst++] = HEAP32[src++] | (isScreen ? 0xff000000 : 0);
+      var num;
+      if (typeof CanvasPixelArray !== 'undefined' && data instanceof CanvasPixelArray) {
+        // IE10/IE11: ImageData objects are backed by the deprecated CanvasPixelArray,
+        // not UInt8ClampedArray. These don't have buffers, so we need to revert
+        // to copying a byte at a time. We do the undefined check because modern
+        // browsers do not define CanvasPixelArray anymore.
+        num = data.length;
+        while (dst < num) {
+          var val = HEAP32[src]; // This is optimized. Instead, we could do {{{ makeGetValue('buffer', 'dst', 'i32') }}};
+          data[dst  ] = val & 0xff;
+          data[dst+1] = (val >> 8) & 0xff;
+          data[dst+2] = (val >> 16) & 0xff;
+          data[dst+3] = isScreen ? 0xff : ((val >> 24) & 0xff);
+          src++;
+          dst += 4;
+        }
+      } else {
+        var data32 = new Uint32Array(data.buffer);
+        num = data32.length;
+        if (isScreen) {
+          while (dst < num) {
+            // HEAP32[src++] is an optimization. Instead, we could do {{{ makeGetValue('buffer', 'dst', 'i32') }}};
+            data32[dst++] = HEAP32[src++] | 0xff000000;
+          }
+        } else {
+          while (dst < num) {
+            data32[dst++] = HEAP32[src++];
+          }
+        }
       }
 #else
       var num = surfData.image.data.length;
diff --git a/src/relooper/Relooper.cpp b/src/relooper/Relooper.cpp
index de69e0ef3520b..389d7447d963f 100644
--- a/src/relooper/Relooper.cpp
+++ b/src/relooper/Relooper.cpp
@@ -308,7 +308,7 @@ void MultipleShape::Render(bool InLoop) {
   }
   RenderLoopPostfix();
   if (Next) Next->Render(InLoop);
-};
+}
 
 // LoopShape
 
@@ -323,7 +323,7 @@ void LoopShape::Render(bool InLoop) {
   Indenter::Unindent();
   PrintIndented("}\n");
   if (Next) Next->Render(InLoop);
-};
+}
 
 // EmulatedShape
 
@@ -350,7 +350,7 @@ void EmulatedShape::Render(bool InLoop) {
   Indenter::Unindent();
   PrintIndented("}\n");
   if (Next) Next->Render(InLoop);
-};
+}
 
 // Relooper
 
@@ -358,8 +358,8 @@ Relooper::Relooper() : Root(NULL), Emulate(false), BlockIdCounter(1), ShapeIdCou
 }
 
 Relooper::~Relooper() {
-  for (int i = 0; i < Blocks.size(); i++) delete Blocks[i];
-  for (int i = 0; i < Shapes.size(); i++) delete Shapes[i];
+  for (unsigned i = 0; i < Blocks.size(); i++) delete Blocks[i];
+  for (unsigned i = 0; i < Shapes.size(); i++) delete Shapes[i];
 }
 
 void Relooper::AddBlock(Block *New) {
@@ -399,7 +399,7 @@ void Relooper::Calculate(Block *Entry) {
     // RAII cleanup. Without splitting, we will be forced to introduce labelled loops to allow
     // reaching the final block
     void SplitDeadEnds() {
-      int TotalCodeSize = 0;
+      unsigned TotalCodeSize = 0;
       for (BlockSet::iterator iter = Live.begin(); iter != Live.end(); iter++) {
         Block *Curr = *iter;
         TotalCodeSize += strlen(Curr->Code);
@@ -451,7 +451,7 @@ void Relooper::Calculate(Block *Entry) {
   Pre.FindLive(Entry);
 
   // Add incoming branches from live blocks, ignoring dead code
-  for (int i = 0; i < Blocks.size(); i++) {
+  for (unsigned i = 0; i < Blocks.size(); i++) {
     Block *Curr = Blocks[i];
     if (!contains(Pre.Live, Curr)) continue;
     for (BlockBranchMap::iterator iter = Curr->BranchesOut.begin(); iter != Curr->BranchesOut.end(); iter++) {
diff --git a/src/relooper/test.txt b/src/relooper/test.txt
index 540f7bdb1a9b1..9bdd40939c1ee 100644
--- a/src/relooper/test.txt
+++ b/src/relooper/test.txt
@@ -91,7 +91,7 @@
   }
   default: {
    var $x_1 = $x_0; 
-   label = -1;
+   label = 8;
    break L1;
   }
   }
@@ -106,7 +106,7 @@
   }
   }
  }
- if (label == -1) {
+ if (label == 8) {
   // code 7
  }
  // code 4
diff --git a/tests/runner.py b/tests/runner.py
index 37e307e9e17e8..72e940cb92c41 100755
--- a/tests/runner.py
+++ b/tests/runner.py
@@ -649,6 +649,7 @@ def reftest(self, expected):
 
   def btest(self, filename, expected=None, reference=None, force_c=False, reference_slack=0, manual_reference=False, post_build=None,
       args=[], outfile='test.html', message='.'): # TODO: use in all other tests
+    if os.environ.get('EMCC_FAST_COMPILER') == '1' and 'LEGACY_GL_EMULATION=1' in args: return self.skip('no legacy gl emulation in fastcomp')
     # if we are provided the source and not a path, use that
     filename_is_src = '\n' in filename
     src = filename if filename_is_src else ''
diff --git a/tests/sdl_canvas.c b/tests/sdl_canvas.c
index 6bd659b8ff51b..cab48985b11b3 100644
--- a/tests/sdl_canvas.c
+++ b/tests/sdl_canvas.c
@@ -62,6 +62,8 @@ int main(int argc, char **argv) {
 
   printf("you should see two lines of text in different colors and a blue rectangle\n");
 
+  SDL_UnlockSurface(screen);
+  
   SDL_Quit();
 
   printf("done.\n");
diff --git a/tests/test_benchmark.py b/tests/test_benchmark.py
index d84f36e469148..625340ea7fda7 100644
--- a/tests/test_benchmark.py
+++ b/tests/test_benchmark.py
@@ -58,7 +58,7 @@ def __init__(self, name, cc, cxx):
 
   def build(self, parent, filename, args, shared_args, emcc_args, native_args, native_exec, lib_builder):
     self.parent = parent
-    if lib_builder: native_args += lib_builder(self.name, native=True, env_init={ 'CC': self.cc, 'CXX': self.cxx })
+    if lib_builder: native_args = native_args + lib_builder(self.name, native=True, env_init={ 'CC': self.cc, 'CXX': self.cxx })
     if not native_exec:
       compiler = self.cxx if filename.endswith('cpp') else self.cc
       process = Popen([compiler, '-O2', '-fno-math-errno', filename, '-o', filename+'.native'] + shared_args + native_args, stdout=PIPE, stderr=parent.stderr_redirect)
@@ -90,7 +90,7 @@ def __init__(self, name, engine, extra_args=[], env={}):
 
   def build(self, parent, filename, args, shared_args, emcc_args, native_args, native_exec, lib_builder):
     self.filename = filename
-    if lib_builder: emcc_args += lib_builder('js', native=False, env_init={})
+    if lib_builder: emcc_args = emcc_args + lib_builder('js', native=False, env_init={})
 
     open('hardcode.py', 'w').write('''
 def process(filename):
diff --git a/tests/test_browser.py b/tests/test_browser.py
index 920c6f8c589d4..20b38bb500fd0 100644
--- a/tests/test_browser.py
+++ b/tests/test_browser.py
@@ -120,6 +120,8 @@ def test_html_source_map(self):
 '''
 
   def test_emscripten_log(self):
+    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('fastcomp uses asm, where call stacks are sometimes less clear')
+
     src = os.path.join(self.get_dir(), 'src.cpp')
     open(src, 'w').write(self.with_report_result(open(path_from_root('tests', 'emscripten_log', 'emscripten_log.cpp')).read()))
 
@@ -680,10 +682,7 @@ def test_sdl_stb_image_data(self):
     self.btest('sdl_stb_image_data.c', reference='screenshot.jpg', args=['-s', 'STB_IMAGE=1', '--preload-file', 'screenshot.not'])
 
   def test_sdl_canvas(self):
-    open(os.path.join(self.get_dir(), 'sdl_canvas.c'), 'w').write(self.with_report_result(open(path_from_root('tests', 'sdl_canvas.c')).read()))
-
-    Popen([PYTHON, EMCC, os.path.join(self.get_dir(), 'sdl_canvas.c'), '-o', 'page.html', '-s', 'LEGACY_GL_EMULATION=1']).communicate()
-    self.run_browser('page.html', '', '/report_result?1')
+    self.btest('sdl_canvas.c', expected='1', args=['-s', 'LEGACY_GL_EMULATION=1'])
 
   def test_sdl_canvas_proxy(self):
     def post():
@@ -1111,6 +1110,8 @@ def test_sdl_audio_quickload(self):
     self.run_browser('page.html', '', '/report_result?1')
 
   def test_sdl_audio_beeps(self):
+    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('todo c++ exceptions in fastcomp')
+
     open(os.path.join(self.get_dir(), 'sdl_audio_beep.cpp'), 'w').write(self.with_report_result(open(path_from_root('tests', 'sdl_audio_beep.cpp')).read()))
 
     # use closure to check for a possible bug with closure minifying away newer Audio() attributes
@@ -1194,10 +1195,7 @@ def test_openal_buffers(self):
     self.btest('openal_buffers.c', '0', args=['--preload-file', 'the_entertainer.wav'],)
 
   def test_glfw(self):
-    open(os.path.join(self.get_dir(), 'glfw.c'), 'w').write(self.with_report_result(open(path_from_root('tests', 'glfw.c')).read()))
-
-    Popen([PYTHON, EMCC, '-O2', os.path.join(self.get_dir(), 'glfw.c'), '-o', 'page.html', '-s', 'LEGACY_GL_EMULATION=1']).communicate()
-    self.run_browser('page.html', '', '/report_result?1')
+    self.btest('glfw.c', '1', args=['-s', 'LEGACY_GL_EMULATION=1'])
 
   def test_egl(self):
     open(os.path.join(self.get_dir(), 'test_egl.c'), 'w').write(self.with_report_result(open(path_from_root('tests', 'test_egl.c')).read()))
@@ -1436,6 +1434,8 @@ def test_sdl_resize(self):
     self.btest('sdl_resize.c', '1')
 
   def test_gc(self):
+    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('flaky in fastcomp and also non-fastcomp -O1, timing issues')
+
     self.btest('browser_gc.cpp', '1')
 
   def test_glshaderinfo(self):
@@ -1622,11 +1622,12 @@ def test_s3tc_crunch_split(self): # load several datafiles/outputs of file packa
     self.btest('s3tc_crunch.c', reference='s3tc_crunch.png', reference_slack=11, args=['--pre-js', 'asset_a.js', '--pre-js', 'asset_b.js', '-s', 'LEGACY_GL_EMULATION=1'])
 
   def test_aniso(self):
-    if SPIDERMONKEY_ENGINE in JS_ENGINES:
+    if SPIDERMONKEY_ENGINE in JS_ENGINES and os.environ.get('EMCC_FAST_COMPILER') != '1':
       # asm.js-ification check
       Popen([PYTHON, EMCC, path_from_root('tests', 'aniso.c'), '-O2', '-g2', '-s', 'LEGACY_GL_EMULATION=1']).communicate()
       Settings.ASM_JS = 1
       self.run_generated_code(SPIDERMONKEY_ENGINE, 'a.out.js')
+      print 'passed asm test'
 
     shutil.copyfile(path_from_root('tests', 'water.dds'), 'water.dds')
     self.btest('aniso.c', reference='aniso.png', reference_slack=2, args=['--preload-file', 'water.dds', '-s', 'LEGACY_GL_EMULATION=1'])
@@ -1681,6 +1682,8 @@ def test_emscripten_async_wget2(self):
     self.btest('http.cpp', expected='0', args=['-I' + path_from_root('tests')])
 
   def test_module(self):
+    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('todo in fastcomp')
+
     Popen([PYTHON, EMCC, path_from_root('tests', 'browser_module.cpp'), '-o', 'module.js', '-O2', '-s', 'SIDE_MODULE=1', '-s', 'DLOPEN_SUPPORT=1', '-s', 'EXPORTED_FUNCTIONS=["_one", "_two"]']).communicate()
     self.btest('browser_main.cpp', args=['-O2', '-s', 'MAIN_MODULE=1', '-s', 'DLOPEN_SUPPORT=1'], expected='8')
 
diff --git a/tests/test_core.py b/tests/test_core.py
index a1b8279a549a0..6442f8942c78f 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -937,6 +937,8 @@ def test_strings(self):
       for named in (0, 1):
         print named
 
+        if os.environ.get('EMCC_FAST_COMPILER') == '1' and named: continue # no named globals in fastcomp
+
         Settings.NAMED_GLOBALS = named
         self.do_run_from_file(src, output, ['wowie', 'too', '74'])
 
diff --git a/tests/test_webgl_context_attributes_common.c b/tests/test_webgl_context_attributes_common.c
index 7131203bffa2a..80506b5003ccc 100644
--- a/tests/test_webgl_context_attributes_common.c
+++ b/tests/test_webgl_context_attributes_common.c
@@ -238,9 +238,9 @@ static void draw() {
  
 }
 
-extern int webglAntialiasSupported();
-extern int webglDepthSupported();
-extern int webglStencilSupported();
+extern int webglAntialiasSupported(void);
+extern int webglDepthSupported(void);
+extern int webglStencilSupported(void);
 
 // Check attributes support in the WebGL implementation (see test_webgl_context_attributes function in test_browser.py)
 // Tests will succeed if they are not.
diff --git a/tools/shared.py b/tools/shared.py
index 5b02fa4c75850..bd0626dc2fe23 100644
--- a/tools/shared.py
+++ b/tools/shared.py
@@ -337,7 +337,7 @@ def find_temp_directory():
 # we re-check sanity when the settings are changed)
 # We also re-check sanity and clear the cache when the version changes
 
-EMSCRIPTEN_VERSION = '1.8.2'
+EMSCRIPTEN_VERSION = '1.8.3'
 
 def generate_sanity():
   return EMSCRIPTEN_VERSION + '|' + get_llvm_target() + '|' + LLVM_ROOT