Merge branch 'fastcomp-by-default' into incoming

21 files changed, 823 insertions, 807 deletions

diff --git a/emcc b/emcc
index 6d8ff6f6..102b7f5d 100755
--- a/emcc
+++ b/emcc
@@ -425,59 +425,6 @@ Options that are modified or new in %s include:
                            -v to Clang, and also enable EMCC_DEBUG
                            to details emcc's operations
 
-  --jcache                 Use a JavaScript cache. This is disabled by
-                           default. When enabled, emcc will store the
-                           results of compilation in a cache and check
-                           the cache when compiling later, something
-                           like what ccache does. This allows incremental
-                           builds - where you are compiling a large
-                           program but only modified a small part of it -
-                           to be much faster (at the cost of more disk
-                           IO for cache accesses). Note that you need
-                           to enable --jcache for both loading and saving
-                           of data, so you must enable it on a full build
-                           for a later incremental build (where you also
-                           enable it) to be sped up.
-
-                           Caching works separately on 4 parts of compilation:
-                           'pre' which is types and global variables; that
-                           information is then fed into 'funcs' which are
-                           the functions (which we parallelize), and then
-                           'post' which adds final information based on
-                           the functions (e.g., do we need long64 support
-                           code). Finally, 'jsfuncs' are JavaScript-level
-                           optimizations. Each of the 4 parts can be cached
-                           separately, but note that they can affect each
-                           other: If you recompile a single C++ file that
-                           changes a global variable - e.g., adds, removes
-                           or modifies a global variable, say by adding
-                           a printf or by adding a compile-time timestamp,
-                           then 'pre' cannot be loaded from the cache. And
-                           since 'pre's output is sent to 'funcs' and 'post',
-                           they will get invalidated as well, and only
-                           'jsfuncs' will be cached. So avoid modifying
-                           globals to let caching work fully.
-
-                           To work around the problem mentioned in the
-                           previous paragraph, you can use
-
-                            emscripten_jcache_printf
-
-                           when adding debug printfs to your code. That
-                           function is specially preprocessed so that it
-                           does not create a constant string global for
-                           its first argument. See emscripten.h for more
-                           details. Note in particular that you need to
-                           already have a call to that function in your
-                           code *before* you add one and do an incremental
-                           build, so that adding an external reference
-                           (also a global property) does not invalidate
-                           everything.
-
-                           Note that you should use -g during the linking
-                           stage (bitcode to JS), for jcache to work
-                           (otherwise, JS minification can confuse it).
-
   --clear-cache            Manually clears the cache of compiled
                            emscripten system libraries (libc++,
                            libc++abi, libc). This is normally
@@ -986,6 +933,7 @@ try:
       logging.warning ('--remove-duplicates is deprecated as it is no longer needed. If you cannot link without it, file a bug with a testcase')
       newargs[i] = ''
     elif newargs[i] == '--jcache':
+      logging.warning('jcache is deprecated')
       jcache = True
       newargs[i] = ''
     elif newargs[i] == '--clear-cache':
@@ -1200,26 +1148,33 @@ try:
     logging.warning('disabling asm.js since embind is not ready for it yet')
     shared.Settings.ASM_JS = 0
 
-  fastcomp = os.environ.get('EMCC_FAST_COMPILER') == '1'
+  fastcomp = os.environ.get('EMCC_FAST_COMPILER') != '0'
 
   if fastcomp:
     shared.Settings.ASM_JS = 1 if opt_level > 0 else 2
-    assert shared.Settings.UNALIGNED_MEMORY == 0, 'forced unaligned memory not supported in fastcomp'
-    assert shared.Settings.CHECK_HEAP_ALIGN == 0, 'check heap align not supported in fastcomp yet'
-    assert shared.Settings.SAFE_DYNCALLS == 0, 'safe dyncalls not supported in fastcomp'
-    assert shared.Settings.ASM_HEAP_LOG == 0, 'asm heap log not supported in fastcomp'
-    assert shared.Settings.LABEL_DEBUG == 0, 'label debug not supported in fastcomp'
-    assert shared.Settings.EXECUTION_TIMEOUT == -1, 'execution timeout not supported in fastcomp'
-    assert shared.Settings.NAMED_GLOBALS == 0, 'named globals not supported in fastcomp'
-    assert shared.Settings.PGO == 0, 'pgo not supported in fastcomp'
-    assert shared.Settings.TARGET_LE32 == 1, 'fastcomp requires le32'
-    assert shared.Settings.USE_TYPED_ARRAYS == 2, 'fastcomp assumes ta2'
-    assert not split_js_file, '--split-js is deprecated and not supported in fastcomp'
-    assert not bind, 'embind not supported in fastcomp yet'
-    assert shared.Settings.MAX_SETJMPS == 20, 'changing MAX_SETJMPS is not supported in fastcomp yet'
-    assert shared.Settings.INIT_HEAP == 0, 'HEAP_INIT is not supported in fastcomp (and should never be needed except for debugging)'
+    try:
+      assert shared.Settings.UNALIGNED_MEMORY == 0, 'forced unaligned memory not supported in fastcomp'
+      assert shared.Settings.CHECK_HEAP_ALIGN == 0, 'check heap align not supported in fastcomp yet'
+      assert shared.Settings.SAFE_DYNCALLS == 0, 'safe dyncalls not supported in fastcomp'
+      assert shared.Settings.ASM_HEAP_LOG == 0, 'asm heap log not supported in fastcomp'
+      assert shared.Settings.LABEL_DEBUG == 0, 'label debug not supported in fastcomp'
+      assert shared.Settings.EXECUTION_TIMEOUT == -1, 'execution timeout not supported in fastcomp'
+      assert shared.Settings.NAMED_GLOBALS == 0, 'named globals not supported in fastcomp'
+      assert shared.Settings.PGO == 0, 'pgo not supported in fastcomp'
+      assert shared.Settings.TARGET_LE32 == 1, 'fastcomp requires le32'
+      assert shared.Settings.USE_TYPED_ARRAYS == 2, 'fastcomp assumes ta2'
+      assert not split_js_file, '--split-js is deprecated and not supported in fastcomp'
+      assert not bind, 'embind not supported in fastcomp yet'
+      assert shared.Settings.MAX_SETJMPS == 20, 'changing MAX_SETJMPS is not supported in fastcomp yet'
+      assert shared.Settings.INIT_HEAP == 0, 'HEAP_INIT is not supported in fastcomp (and should never be needed except for debugging)'
+      assert not shared.Settings.RUNTIME_TYPE_INFO, 'RUNTIME_TYPE_INFO is not supported in fastcomp'
+      assert not shared.Settings.CORRUPTION_CHECK, 'CORRUPTION_CHECK is not supported in asm.js mode, which is what fastcomp can emit (you can use non-asm.js mode in non-fastcomp)'
+    except Exception, e:
+      logging.error('Compiler settings are incompatible with fastcomp. You can fall back to the older compiler core, although that is not recommended, see https://github.com/kripken/emscripten/wiki/LLVM-Backend')
+      raise e
+
     if jcache:
-      logging.warning('jcache is not supported in fastcomp (you should not need it anyhow), disabling')
+      logging.warning('jcache is deprecated and not supported in fastcomp (you should not need it anyhow), disabling')
       jcache = False
 
     fastcomp_opts = ['-pnacl-abi-simplify-preopt', '-pnacl-abi-simplify-postopt']
@@ -1284,7 +1239,7 @@ try:
     shared.Settings.LINKABLE = 1 # TODO: add FORCE_DCE option for the brave people that do want to dce here and in side modules
     debug_level = max(debug_level, 2)
 
-  if shared.Settings.ASSERTIONS and shared.Settings.ALIASING_FUNCTION_POINTERS:
+  if not fastcomp and shared.Settings.ASSERTIONS and shared.Settings.ALIASING_FUNCTION_POINTERS:
     logging.warning('ALIASING_FUNCTION_POINTERS is on, function pointer comparisons may be invalid across types')
 
   if shared.Settings.STB_IMAGE and final_suffix in JS_CONTAINING_SUFFIXES:
diff --git a/emscripten.py b/emscripten.py
index 59a0666c..6b49a3cc 100755
--- a/emscripten.py
+++ b/emscripten.py
@@ -1257,7 +1257,7 @@ Runtime.stackRestore = function(top) { asm['stackRestore'](top) };
 
   if DEBUG: logging.debug('  emscript: final python processing took %s seconds' % (time.time() - t))
 
-if os.environ.get('EMCC_FAST_COMPILER') == '1':
+if os.environ.get('EMCC_FAST_COMPILER') != '0':
   emscript = emscript_fast
 
 def main(args, compiler_engine, cache, jcache, relooper, temp_files, DEBUG, DEBUG_CACHE):
diff --git a/src/library_gc.js b/src/library_gc.js
index b3dae0e9..d86f2d15 100644
--- a/src/library_gc.js
+++ b/src/library_gc.js
@@ -1,4 +1,6 @@
 
+// WARNING: this is deprecated. You should just build Boehm from source, it is much faster than the toy version written in emscripten
+
 if (GC_SUPPORT) {
   EXPORTED_FUNCTIONS['_calloc'] = 1;
   EXPORTED_FUNCTIONS['_realloc'] = 1;
diff --git a/src/preamble.js b/src/preamble.js
index 27a98422..28a1dcbc 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -194,9 +194,6 @@ function SAFE_HEAP_STORE(dest, value, bytes, isFloat) {
 }
 
 function SAFE_HEAP_LOAD(dest, bytes, isFloat, unsigned) {
-#if SAFE_HEAP_LOG
-  Module.print('SAFE_HEAP load: ' + [dest, bytes, isFloat, unsigned]);
-#endif
   assert(dest > 0, 'segmentation fault');
   assert(dest % bytes === 0);
   assert(dest < Math.max(DYNAMICTOP, STATICTOP));
@@ -204,6 +201,9 @@ function SAFE_HEAP_LOAD(dest, bytes, isFloat, unsigned) {
   var type = getSafeHeapType(bytes, isFloat);
   var ret = getValue(dest, type, 1);
   if (unsigned) ret = unSign(ret, parseInt(type.substr(1)), 1);
+#if SAFE_HEAP_LOG
+  Module.print('SAFE_HEAP load: ' + [dest, ret, bytes, isFloat, unsigned]);
+#endif
   return ret;
 }
 
diff --git a/src/settings.js b/src/settings.js
index c8114059..1c6b998e 100644
--- a/src/settings.js
+++ b/src/settings.js
@@ -446,7 +446,7 @@ var HEADLESS = 0; // If 1, will include shim code that tries to 'fake' a browser
 var BENCHMARK = 0; // If 1, will just time how long main() takes to execute, and not
                    // print out anything at all whatsoever. This is useful for benchmarking.
 
-var ASM_JS = 0; // If 1, generate code in asm.js format. If 2, emits the same code except
+var ASM_JS = 1; // If 1, generate code in asm.js format. If 2, emits the same code except
                 // for omitting 'use asm'
 
 var PGO = 0; // Enables profile-guided optimization in the form of runtime checks for
diff --git a/system/include/emscripten/emscripten.h b/system/include/emscripten/emscripten.h
index b92d920c..852a8e0d 100644
--- a/system/include/emscripten/emscripten.h
+++ b/system/include/emscripten/emscripten.h
@@ -40,10 +40,15 @@ extern "C" {
 #define EM_ASM(...) emscripten_asm_const(#__VA_ARGS__)
 
 /*
- * Input-output versions of EM_ASM. EM_ASM_INT receives arguments of
- * either int or double type and returns an int; EM_ASM_DOUBLE
- * receives similar arguments (int or double) but returns a double.
- * Arguments arrive as $0, $1 etc; output value should be returned:
+ * Input-output versions of EM_ASM.
+ *
+ * EM_ASM_ (an extra _ is added) allows sending values (ints
+ * or doubles) into the code. If you also want a return value,
+ * EM_ASM_INT receives arguments (of int or double type)
+ * and returns an int; EM_ASM_DOUBLE does the same and returns
+ * a double.
+ *
+ * Arguments arrive as $0, $1 etc. The output value should be returned:
  *
  *    int x = EM_ASM_INT({
  *      console.log('I received: ' + [$0, $1]);
@@ -54,6 +59,7 @@ extern "C" {
  * (int or double) but *not* to pass any values, you can use
  * EM_ASM_INT_V and EM_ASM_DOUBLE_V respectively.
  */
+#define EM_ASM_(code, ...) emscripten_asm_const_int(#code, __VA_ARGS__)
 #define EM_ASM_INT(code, ...) emscripten_asm_const_int(#code, __VA_ARGS__)
 #define EM_ASM_DOUBLE(code, ...) emscripten_asm_const_double(#code, __VA_ARGS__)
 #define EM_ASM_INT_V(code) emscripten_asm_const_int(#code)
diff --git a/system/include/gc.h b/system/include/gc.h
index a21fd410..affa615f 100644
--- a/system/include/gc.h
+++ b/system/include/gc.h
@@ -1,5 +1,7 @@
 /*
  * Boehm-compatible GC API
+ *
+ * WARNING: this is deprecated. You should just build Boehm from source, it is much faster than the toy version written in emscripten
  */
 #ifndef _GC_H_INCLUDED
 #define _GC_H_INCLUDED
diff --git a/tests/core/test_inlinejs3.in b/tests/core/test_inlinejs3.in
index 9ddd5907..12e31007 100644
--- a/tests/core/test_inlinejs3.in
+++ b/tests/core/test_inlinejs3.in
@@ -7,6 +7,7 @@ int main(int argc, char **argv) {
   for (int i = 0; i < 3; i++) {
     EM_ASM(Module.print('hello dere3'); Module.print('hello dere' + 4););
   }
+  EM_ASM_({ Module.print('hello input ' + $0) }, 123);
   int sum = 0;
   for (int i = 0; i < argc * 3; i++) {
     sum += EM_ASM_INT({
diff --git a/tests/core/test_inlinejs3.out b/tests/core/test_inlinejs3.out
index c293e80b..1f64a89a 100644
--- a/tests/core/test_inlinejs3.out
+++ b/tests/core/test_inlinejs3.out
@@ -6,6 +6,7 @@ hello dere3
 hello dere4
 hello dere3
 hello dere4
+hello input 123
 i: 0,0.00
 i: 1,0.08
 i: 2,0.17
diff --git a/tests/runner.py b/tests/runner.py
index 501299c7..32575a1a 100755
--- a/tests/runner.py
+++ b/tests/runner.py
@@ -27,6 +27,19 @@ sys.path += [path_from_root(''), path_from_root('third_party/websockify')]
 import tools.shared
 from tools.shared import *
 
+# Utils
+
+def nonfastcomp(test):
+  try:
+    old_fastcomp = os.environ.get('EMCC_FAST_COMPILER')
+    os.environ['EMCC_FAST_COMPILER'] = '0'
+    test()
+  finally:
+    if old_fastcomp is None:
+      del os.environ['EMCC_FAST_COMPILER']
+    else:
+      os.environ['EMCC_FAST_COMPILER'] = old_fastcomp
+
 # Sanity check for config
 
 try:
@@ -36,10 +49,7 @@ except:
 
 # Core test runner class, shared between normal tests and benchmarks
 checked_sanity = False
-if os.environ.get('EMCC_FAST_COMPILER') == '1':
-  test_modes = ['default', 'asm1', 'asm2', 'asm3', 'asm2f', 'asm2g']
-else:
-  test_modes = ['default', 'o1', 'o2', 'asm1', 'asm2', 'asm3', 'asm2f', 'asm2g', 'asm2x86', 's_0_0', 's_0_1']
+test_modes = ['default', 'asm1', 'asm2', 'asm3', 'asm2f', 'asm2g', 'slow2', 'slow2asm', 's_0_0', 's_0_1']
 test_index = 0
 
 class RunnerCore(unittest.TestCase):
diff --git a/tests/test_benchmark.py b/tests/test_benchmark.py
index 023ac1e2..2bc34c60 100644
--- a/tests/test_benchmark.py
+++ b/tests/test_benchmark.py
@@ -134,7 +134,6 @@ try:
     #JSBenchmarker('sm-f32-3.2', SPIDERMONKEY_ENGINE, ['-s', 'PRECISE_F32=2'], env={ 'LLVM': LLVM_3_2 }),
     #JSBenchmarker('sm-f32-3.3', SPIDERMONKEY_ENGINE, ['-s', 'PRECISE_F32=2'], env={ 'LLVM': LLVM_3_3 }),
     #JSBenchmarker('sm-f32-3.4', SPIDERMONKEY_ENGINE, ['-s', 'PRECISE_F32=2'], env={ 'LLVM': LLVM_3_4 }),
-    #JSBenchmarker('sm-fc',         SPIDERMONKEY_ENGINE, env={ 'EMCC_FAST_COMPILER': '1' }),
     #JSBenchmarker('sm-noasm',     SPIDERMONKEY_ENGINE + ['--no-asmjs']),
     #JSBenchmarker('sm-noasm-f32', SPIDERMONKEY_ENGINE + ['--no-asmjs'], ['-s', 'PRECISE_F32=2']),
     #JSBenchmarker('v8',           V8_ENGINE)
diff --git a/tests/test_browser.py b/tests/test_browser.py
index c1d1caab..f2e17ea0 100644
--- a/tests/test_browser.py
+++ b/tests/test_browser.py
@@ -1,5 +1,5 @@
 import BaseHTTPServer, multiprocessing, os, shutil, subprocess, unittest, zlib, webbrowser, time, shlex
-from runner import BrowserCore, path_from_root
+from runner import BrowserCore, path_from_root, nonfastcomp
 from tools.shared import *
 
 # User can specify an environment variable EMSCRIPTEN_BROWSER to force the browser test suite to
@@ -120,8 +120,6 @@ If manually bisecting:
 '''
 
   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()))
 
@@ -143,191 +141,193 @@ If manually bisecting:
       os.chdir(cwd)
 
   def test_split(self):
-    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('no --split in fastcomp, deprecated')
+    def nfc():
+      # test HTML generation.
+      self.reftest(path_from_root('tests', 'htmltest.png'))
+      output = Popen([PYTHON, EMCC, path_from_root('tests', 'hello_world_sdl.cpp'), '-o', 'something.js', '--split', '100', '--pre-js', 'reftest.js']).communicate()
+      assert os.path.exists(os.path.join(self.get_dir(), 'something.js')), 'must be main js file'
+      assert os.path.exists(os.path.join(self.get_dir(), 'something_functions.js')), 'must be functions js file'
+      assert os.path.exists(os.path.join(self.get_dir(), 'something.include.html')), 'must be js include file'
 
-    # test HTML generation.
-    self.reftest(path_from_root('tests', 'htmltest.png'))
-    output = Popen([PYTHON, EMCC, path_from_root('tests', 'hello_world_sdl.cpp'), '-o', 'something.js', '--split', '100', '--pre-js', 'reftest.js']).communicate()
-    assert os.path.exists(os.path.join(self.get_dir(), 'something.js')), 'must be main js file'
-    assert os.path.exists(os.path.join(self.get_dir(), 'something_functions.js')), 'must be functions js file'
-    assert os.path.exists(os.path.join(self.get_dir(), 'something.include.html')), 'must be js include file'
-
-    open(os.path.join(self.get_dir(), 'something.html'), 'w').write('''
-
-    <!doctype html>
-    <html lang="en-us">
-      <head>
-        <meta charset="utf-8">
-        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
-        <title>Emscripten-Generated Code</title>
-        <style>
-          .emscripten { padding-right: 0; margin-left: auto; margin-right: auto; display: block; }
-          canvas.emscripten { border: 1px solid black; }
-          textarea.emscripten { font-family: monospace; width: 80%; }
-          div.emscripten { text-align: center; }
-        </style>
-      </head>
-      <body>
-        <hr/>
-        <div class="emscripten" id="status">Downloading...</div>
-        <div class="emscripten">
-          <progress value="0" max="100" id="progress" hidden=1></progress>
-        </div>
-        <canvas class="emscripten" id="canvas" oncontextmenu="event.preventDefault()"></canvas>
-        <hr/>
-        <div class="emscripten"><input type="button" value="fullscreen" onclick="Module.requestFullScreen()"></div>
-        <hr/>
-        <textarea class="emscripten" id="output" rows="8"></textarea>
-        <hr>
-        <script type='text/javascript'>
-          // connect to canvas
-          var Module = {
-            preRun: [],
-            postRun: [],
-            print: (function() {
-              var element = document.getElementById('output');
-              element.value = ''; // clear browser cache
-              return function(text) {
-                // These replacements are necessary if you render to raw HTML
-                //text = text.replace(/&/g, "&amp;");
-                //text = text.replace(/</g, "&lt;");
-                //text = text.replace(/>/g, "&gt;");
-                //text = text.replace('\\n', '<br>', 'g');
-                element.value += text + "\\n";
-                element.scrollTop = element.scrollHeight; // focus on bottom
-              };
-            })(),
-            printErr: function(text) {
-              if (0) { // XXX disabled for safety typeof dump == 'function') {
-                dump(text + '\\n'); // fast, straight to the real console
-              } else {
-                console.log(text);
-              }
-            },
-            canvas: document.getElementById('canvas'),
-            setStatus: function(text) {
-              if (Module.setStatus.interval) clearInterval(Module.setStatus.interval);
-              var m = text.match(/([^(]+)\((\d+(\.\d+)?)\/(\d+)\)/);
-              var statusElement = document.getElementById('status');
-              var progressElement = document.getElementById('progress');
-              if (m) {
-                text = m[1];
-                progressElement.value = parseInt(m[2])*100;
-                progressElement.max = parseInt(m[4])*100;
-                progressElement.hidden = false;
-              } else {
-                progressElement.value = null;
-                progressElement.max = null;
-                progressElement.hidden = true;
+      open(os.path.join(self.get_dir(), 'something.html'), 'w').write('''
+
+      <!doctype html>
+      <html lang="en-us">
+        <head>
+          <meta charset="utf-8">
+          <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+          <title>Emscripten-Generated Code</title>
+          <style>
+            .emscripten { padding-right: 0; margin-left: auto; margin-right: auto; display: block; }
+            canvas.emscripten { border: 1px solid black; }
+            textarea.emscripten { font-family: monospace; width: 80%; }
+            div.emscripten { text-align: center; }
+          </style>
+        </head>
+        <body>
+          <hr/>
+          <div class="emscripten" id="status">Downloading...</div>
+          <div class="emscripten">
+            <progress value="0" max="100" id="progress" hidden=1></progress>
+          </div>
+          <canvas class="emscripten" id="canvas" oncontextmenu="event.preventDefault()"></canvas>
+          <hr/>
+          <div class="emscripten"><input type="button" value="fullscreen" onclick="Module.requestFullScreen()"></div>
+          <hr/>
+          <textarea class="emscripten" id="output" rows="8"></textarea>
+          <hr>
+          <script type='text/javascript'>
+            // connect to canvas
+            var Module = {
+              preRun: [],
+              postRun: [],
+              print: (function() {
+                var element = document.getElementById('output');
+                element.value = ''; // clear browser cache
+                return function(text) {
+                  // These replacements are necessary if you render to raw HTML
+                  //text = text.replace(/&/g, "&amp;");
+                  //text = text.replace(/</g, "&lt;");
+                  //text = text.replace(/>/g, "&gt;");
+                  //text = text.replace('\\n', '<br>', 'g');
+                  element.value += text + "\\n";
+                  element.scrollTop = element.scrollHeight; // focus on bottom
+                };
+              })(),
+              printErr: function(text) {
+                if (0) { // XXX disabled for safety typeof dump == 'function') {
+                  dump(text + '\\n'); // fast, straight to the real console
+                } else {
+                  console.log(text);
+                }
+              },
+              canvas: document.getElementById('canvas'),
+              setStatus: function(text) {
+                if (Module.setStatus.interval) clearInterval(Module.setStatus.interval);
+                var m = text.match(/([^(]+)\((\d+(\.\d+)?)\/(\d+)\)/);
+                var statusElement = document.getElementById('status');
+                var progressElement = document.getElementById('progress');
+                if (m) {
+                  text = m[1];
+                  progressElement.value = parseInt(m[2])*100;
+                  progressElement.max = parseInt(m[4])*100;
+                  progressElement.hidden = false;
+                } else {
+                  progressElement.value = null;
+                  progressElement.max = null;
+                  progressElement.hidden = true;
+                }
+                statusElement.innerHTML = text;
+              },
+              totalDependencies: 0,
+              monitorRunDependencies: function(left) {
+                this.totalDependencies = Math.max(this.totalDependencies, left);
+                Module.setStatus(left ? 'Preparing... (' + (this.totalDependencies-left) + '/' + this.totalDependencies + ')' : 'All downloads complete.');
               }
-              statusElement.innerHTML = text;
-            },
-            totalDependencies: 0,
-            monitorRunDependencies: function(left) {
-              this.totalDependencies = Math.max(this.totalDependencies, left);
-              Module.setStatus(left ? 'Preparing... (' + (this.totalDependencies-left) + '/' + this.totalDependencies + ')' : 'All downloads complete.');
-            }
-          };
-          Module.setStatus('Downloading...');
-        </script>''' + open(os.path.join(self.get_dir(), 'something.include.html')).read() + '''
-      </body>
-    </html>
-    ''')
+            };
+            Module.setStatus('Downloading...');
+          </script>''' + open(os.path.join(self.get_dir(), 'something.include.html')).read() + '''
+        </body>
+      </html>
+      ''')
 
-    self.run_browser('something.html', 'You should see "hello, world!" and a colored cube.', '/report_result?0')
+      self.run_browser('something.html', 'You should see "hello, world!" and a colored cube.', '/report_result?0')
+
+    nonfastcomp(nfc)
 
   def test_split_in_source_filenames(self):
-    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('no --split in fastcomp, deprecated')
-
-    self.reftest(path_from_root('tests', 'htmltest.png'))
-    output = Popen([PYTHON, EMCC, path_from_root('tests', 'hello_world_sdl.cpp'), '-o', 'something.js', '-g', '--split', '100', '--pre-js', 'reftest.js']).communicate()
-    assert os.path.exists(os.path.join(self.get_dir(), 'something.js')), 'must be main js file'
-    assert os.path.exists(os.path.join(self.get_dir(), 'something', 'hello_world_sdl.cpp.js')), 'must be functions js file'
-    assert os.path.exists(os.path.join(self.get_dir(), 'something.include.html')), 'must be js include file'
-
-    open(os.path.join(self.get_dir(), 'something.html'), 'w').write('''
-
-    <!doctype html>
-    <html lang="en-us">
-      <head>
-        <meta charset="utf-8">
-        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
-        <title>Emscripten-Generated Code</title>
-        <style>
-          .emscripten { padding-right: 0; margin-left: auto; margin-right: auto; display: block; }
-          canvas.emscripten { border: 1px solid black; }
-          textarea.emscripten { font-family: monospace; width: 80%; }
-          div.emscripten { text-align: center; }
-        </style>
-      </head>
-      <body>
-        <hr/>
-        <div class="emscripten" id="status">Downloading...</div>
-        <div class="emscripten">
-          <progress value="0" max="100" id="progress" hidden=1></progress>
-        </div>
-        <canvas class="emscripten" id="canvas" oncontextmenu="event.preventDefault()"></canvas>
-        <hr/>
-        <div class="emscripten"><input type="button" value="fullscreen" onclick="Module.requestFullScreen()"></div>
-        <hr/>
-        <textarea class="emscripten" id="output" rows="8"></textarea>
-        <hr>
-        <script type='text/javascript'>
-          // connect to canvas
-          var Module = {
-            preRun: [],
-            postRun: [],
-            print: (function() {
-              var element = document.getElementById('output');
-              element.value = ''; // clear browser cache
-              return function(text) {
-                // These replacements are necessary if you render to raw HTML
-                //text = text.replace(/&/g, "&amp;");
-                //text = text.replace(/</g, "&lt;");
-                //text = text.replace(/>/g, "&gt;");
-                //text = text.replace('\\n', '<br>', 'g');
-                element.value += text + "\\n";
-                element.scrollTop = element.scrollHeight; // focus on bottom
-              };
-            })(),
-            printErr: function(text) {
-              if (0) { // XXX disabled for safety typeof dump == 'function') {
-                dump(text + '\\n'); // fast, straight to the real console
-              } else {
-                console.log(text);
-              }
-            },
-            canvas: document.getElementById('canvas'),
-            setStatus: function(text) {
-              if (Module.setStatus.interval) clearInterval(Module.setStatus.interval);
-              var m = text.match(/([^(]+)\((\d+(\.\d+)?)\/(\d+)\)/);
-              var statusElement = document.getElementById('status');
-              var progressElement = document.getElementById('progress');
-              if (m) {
-                text = m[1];
-                progressElement.value = parseInt(m[2])*100;
-                progressElement.max = parseInt(m[4])*100;
-                progressElement.hidden = false;
-              } else {
-                progressElement.value = null;
-                progressElement.max = null;
-                progressElement.hidden = true;
+    def nfc():
+      self.reftest(path_from_root('tests', 'htmltest.png'))
+      output = Popen([PYTHON, EMCC, path_from_root('tests', 'hello_world_sdl.cpp'), '-o', 'something.js', '-g', '--split', '100', '--pre-js', 'reftest.js']).communicate()
+      assert os.path.exists(os.path.join(self.get_dir(), 'something.js')), 'must be main js file'
+      assert os.path.exists(os.path.join(self.get_dir(), 'something', 'hello_world_sdl.cpp.js')), 'must be functions js file'
+      assert os.path.exists(os.path.join(self.get_dir(), 'something.include.html')), 'must be js include file'
+
+      open(os.path.join(self.get_dir(), 'something.html'), 'w').write('''
+
+      <!doctype html>
+      <html lang="en-us">
+        <head>
+          <meta charset="utf-8">
+          <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+          <title>Emscripten-Generated Code</title>
+          <style>
+            .emscripten { padding-right: 0; margin-left: auto; margin-right: auto; display: block; }
+            canvas.emscripten { border: 1px solid black; }
+            textarea.emscripten { font-family: monospace; width: 80%; }
+            div.emscripten { text-align: center; }
+          </style>
+        </head>
+        <body>
+          <hr/>
+          <div class="emscripten" id="status">Downloading...</div>
+          <div class="emscripten">
+            <progress value="0" max="100" id="progress" hidden=1></progress>
+          </div>
+          <canvas class="emscripten" id="canvas" oncontextmenu="event.preventDefault()"></canvas>
+          <hr/>
+          <div class="emscripten"><input type="button" value="fullscreen" onclick="Module.requestFullScreen()"></div>
+          <hr/>
+          <textarea class="emscripten" id="output" rows="8"></textarea>
+          <hr>
+          <script type='text/javascript'>
+            // connect to canvas
+            var Module = {
+              preRun: [],
+              postRun: [],
+              print: (function() {
+                var element = document.getElementById('output');
+                element.value = ''; // clear browser cache
+                return function(text) {
+                  // These replacements are necessary if you render to raw HTML
+                  //text = text.replace(/&/g, "&amp;");
+                  //text = text.replace(/</g, "&lt;");
+                  //text = text.replace(/>/g, "&gt;");
+                  //text = text.replace('\\n', '<br>', 'g');
+                  element.value += text + "\\n";
+                  element.scrollTop = element.scrollHeight; // focus on bottom
+                };
+              })(),
+              printErr: function(text) {
+                if (0) { // XXX disabled for safety typeof dump == 'function') {
+                  dump(text + '\\n'); // fast, straight to the real console
+                } else {
+                  console.log(text);
+                }
+              },
+              canvas: document.getElementById('canvas'),
+              setStatus: function(text) {
+                if (Module.setStatus.interval) clearInterval(Module.setStatus.interval);
+                var m = text.match(/([^(]+)\((\d+(\.\d+)?)\/(\d+)\)/);
+                var statusElement = document.getElementById('status');
+                var progressElement = document.getElementById('progress');
+                if (m) {
+                  text = m[1];
+                  progressElement.value = parseInt(m[2])*100;
+                  progressElement.max = parseInt(m[4])*100;
+                  progressElement.hidden = false;
+                } else {
+                  progressElement.value = null;
+                  progressElement.max = null;
+                  progressElement.hidden = true;
+                }
+                statusElement.innerHTML = text;
+              },
+              totalDependencies: 0,
+              monitorRunDependencies: function(left) {
+                this.totalDependencies = Math.max(this.totalDependencies, left);
+                Module.setStatus(left ? 'Preparing... (' + (this.totalDependencies-left) + '/' + this.totalDependencies + ')' : 'All downloads complete.');
               }
-              statusElement.innerHTML = text;
-            },
-            totalDependencies: 0,
-            monitorRunDependencies: function(left) {
-              this.totalDependencies = Math.max(this.totalDependencies, left);
-              Module.setStatus(left ? 'Preparing... (' + (this.totalDependencies-left) + '/' + this.totalDependencies + ')' : 'All downloads complete.');
-            }
-          };
-          Module.setStatus('Downloading...');
-        </script>''' + open(os.path.join(self.get_dir(), 'something.include.html')).read() + '''
-      </body>
-    </html>
-    ''')
+            };
+            Module.setStatus('Downloading...');
+          </script>''' + open(os.path.join(self.get_dir(), 'something.include.html')).read() + '''
+        </body>
+      </html>
+      ''')
 
-    self.run_browser('something.html', 'You should see "hello, world!" and a colored cube.', '/report_result?0')
+      self.run_browser('something.html', 'You should see "hello, world!" and a colored cube.', '/report_result?0')
+
+    nonfastcomp(nfc)
 
   def test_compression(self):
     open(os.path.join(self.get_dir(), 'main.cpp'), 'w').write(self.with_report_result(r'''
@@ -1495,11 +1495,6 @@ keydown(100);keyup(100); // trigger the end
   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):
     self.btest('glshaderinfo.cpp', '1')
 
@@ -1706,7 +1701,7 @@ void *getBindBuffer() {
     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 and os.environ.get('EMCC_FAST_COMPILER') != '1':
+    if SPIDERMONKEY_ENGINE in JS_ENGINES:
       # 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
@@ -1766,10 +1761,10 @@ void *getBindBuffer() {
     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')
+    def nfc():
+      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')
+    nonfastcomp(nfc)
 
   def test_mmap_file(self):
     open(self.in_dir('data.dat'), 'w').write('data from the file ' + ('.' * 9000))
diff --git a/tests/test_core.py b/tests/test_core.py
index c4bfcfa3..19bb9ca1 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -512,33 +512,45 @@ class T(RunnerCore): # Short name, to make it more fun to use manually on the co
     self.do_run(open(path_from_root('tests', 'cube2md5.cpp')).read(), open(path_from_root('tests', 'cube2md5.ok')).read())
 
   def test_cube2hash(self):
-    try:
-      old_chunk_size = os.environ.get('EMSCRIPT_MAX_CHUNK_SIZE') or ''
-      os.environ['EMSCRIPT_MAX_CHUNK_SIZE'] = '1' # test splitting out each function to a chunk in emscripten.py (21 functions here)
-
-      # A good test of i64 math
-      if Settings.USE_TYPED_ARRAYS != 2: return self.skip('requires ta2 C-style memory aliasing')
-      self.do_run('', 'Usage: hashstring <seed>',
-                  libraries=self.get_library('cube2hash', ['cube2hash.bc'], configure=None),
-                  includes=[path_from_root('tests', 'cube2hash')])
-
-      for text, output in [('fleefl', '892BDB6FD3F62E863D63DA55851700FDE3ACF30204798CE9'),
-                           ('fleefl2', 'AA2CC5F96FC9D540CA24FDAF1F71E2942753DB83E8A81B61'),
-                           ('64bitisslow', '64D8470573635EC354FEE7B7F87C566FCAF1EFB491041670')]:
-        self.do_run('', 'hash value: ' + output, [text], no_build=True)
-    finally:
-      os.environ['EMSCRIPT_MAX_CHUNK_SIZE'] = old_chunk_size
-
-    assert 'asm1' in test_modes
-    if self.run_name == 'asm1' and not os.environ.get('EMCC_FAST_COMPILER'):
-      assert Settings.RELOOP
-      generated = open('src.cpp.o.js').read()
-      main = generated[generated.find('function _main'):]
-      main = main[:main.find('\n}')]
-      num_vars = 0
-      for v in re.findall('var [^;]+;', main):
-        num_vars += v.count(',') + 1
-      assert num_vars == 10, 'no variable elimination should have been run, but seeing %d' % num_vars
+    # extra testing for various codegen modes
+    for x86 in [0, 1] if self.run_name == 'asm2' else [0]:
+      print 'x86', x86
+      try:
+        old_x86 = os.environ.get('EMCC_LLVM_TARGET') or ''
+        if x86:
+          os.environ['EMCC_LLVM_TARGET'] = "i386-pc-linux-gnu"
+        try:
+          old_fastcomp = os.environ.get('EMCC_FAST_COMPILER') or ''
+          if x86:
+            os.environ['EMCC_FAST_COMPILER'] = "0"
+          try:
+            old_chunk_size = os.environ.get('EMSCRIPT_MAX_CHUNK_SIZE') or ''
+            os.environ['EMSCRIPT_MAX_CHUNK_SIZE'] = '1' # test splitting out each function to a chunk in emscripten.py (21 functions here)
+
+            # A good test of i64 math
+            if Settings.USE_TYPED_ARRAYS != 2: return self.skip('requires ta2 C-style memory aliasing')
+            self.do_run('', 'Usage: hashstring <seed>',
+                        libraries=self.get_library('cube2hash', ['cube2hash.bc'], configure=None, cache_name_extra=str(x86)),
+                        includes=[path_from_root('tests', 'cube2hash')])
+
+            for text, output in [('fleefl', '892BDB6FD3F62E863D63DA55851700FDE3ACF30204798CE9'),
+                                 ('fleefl2', 'AA2CC5F96FC9D540CA24FDAF1F71E2942753DB83E8A81B61'),
+                                 ('64bitisslow', '64D8470573635EC354FEE7B7F87C566FCAF1EFB491041670')]:
+              self.do_run('', 'hash value: ' + output, [text], no_build=True)
+          finally:
+            os.environ['EMSCRIPT_MAX_CHUNK_SIZE'] = old_chunk_size
+        finally:
+          if x86:
+            if old_fastcomp:
+              os.environ['EMCC_FAST_COMPILER'] = old_fastcomp
+            else:
+              del os.environ['EMCC_FAST_COMPILER']
+      finally:
+        if x86:
+          if old_x86:
+            os.environ['EMCC_LLVM_TARGET'] = old_x86
+          else:
+            del os.environ['EMCC_LLVM_TARGET']
 
   def test_unaligned(self):
       if Settings.QUANTUM_SIZE == 1: return self.skip('No meaning to unaligned addresses in q1')
@@ -951,7 +963,7 @@ class T(RunnerCore): # Short name, to make it more fun to use manually on the co
       for named in (0, 1):
         print named
 
-        if os.environ.get('EMCC_FAST_COMPILER') == '1' and named: continue # no named globals in fastcomp
+        if os.environ.get('EMCC_FAST_COMPILER') != '0' and named: continue # no named globals in fastcomp
 
         Settings.NAMED_GLOBALS = named
         self.do_run_from_file(src, output, ['wowie', 'too', '74'])
@@ -1138,7 +1150,7 @@ class T(RunnerCore): # Short name, to make it more fun to use manually on the co
     self.do_run_from_file(src, output)
 
   def test_longjmp_repeat(self):
-    if os.environ.get('EMCC_FAST_COMPILER') != '1': Settings.MAX_SETJMPS = 1 # todo: do this more strict thing in fastcomp too
+    if os.environ.get('EMCC_FAST_COMPILER') == '0': Settings.MAX_SETJMPS = 1 # todo: do this more strict thing in fastcomp too
     test_path = path_from_root('tests', 'core', 'test_longjmp_repeat')
     src, output = (test_path + s for s in ('.in', '.out'))
     self.do_run_from_file(src, output)
@@ -1162,7 +1174,7 @@ class T(RunnerCore): # Short name, to make it more fun to use manually on the co
       self.do_run_from_file(src, output)
 
   def test_setjmp_many(self):
-    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('todo in fastcomp: make MAX_SETJMPS take effect')
+    if os.environ.get('EMCC_FAST_COMPILER') != '0': return self.skip('todo in fastcomp: make MAX_SETJMPS take effect')
 
     src = r'''
       #include <stdio.h>
@@ -1930,7 +1942,7 @@ def process(filename):
 
   def test_inlinejs(self):
       if not self.is_le32(): return self.skip('le32 needed for inline js')
-      if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('fastcomp only supports EM_ASM')
+      if os.environ.get('EMCC_FAST_COMPILER') != '0': return self.skip('fastcomp only supports EM_ASM')
 
       test_path = path_from_root('tests', 'core', 'test_inlinejs')
       src, output = (test_path + s for s in ('.in', '.out'))
@@ -1943,7 +1955,7 @@ def process(filename):
 
   def test_inlinejs2(self):
       if not self.is_le32(): return self.skip('le32 needed for inline js')
-      if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('fastcomp only supports EM_ASM')
+      if os.environ.get('EMCC_FAST_COMPILER') != '0': return self.skip('fastcomp only supports EM_ASM')
 
       test_path = path_from_root('tests', 'core', 'test_inlinejs2')
       src, output = (test_path + s for s in ('.in', '.out'))
@@ -2749,7 +2761,7 @@ The current type of b is: 9
     self.do_run(main, 'supp: 54,2\nmain: 56\nsupp see: 543\nmain see: 76\nok.')
 
   def can_dlfcn(self):
-    if os.environ.get('EMCC_FAST_COMPILER') == '1':
+    if os.environ.get('EMCC_FAST_COMPILER') != '0':
       self.skip('todo in fastcomp')
       return False
 
@@ -3171,7 +3183,7 @@ def process(filename):
 
   def test_dlfcn_self(self):
     if Settings.USE_TYPED_ARRAYS == 1: return self.skip('Does not work with USE_TYPED_ARRAYS=1')
-    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('todo in fastcomp')
+    if os.environ.get('EMCC_FAST_COMPILER') != '0': return self.skip('todo in fastcomp')
     Settings.DLOPEN_SUPPORT = 1
 
     def post(filename):
@@ -4673,25 +4685,6 @@ return malloc(size);
       main = main[:main.find('\n}')]
       assert main.count('\n') <= 7, ('must not emit too many postSets: %d' % main.count('\n')) + ' : ' + main
 
-    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('fastcomp always aliases pointers')
-
-    assert 'asm2g' in test_modes
-    if self.run_name == 'asm2g':
-      results = {}
-      original = open('src.cpp.o.js').read()
-      results[Settings.ALIASING_FUNCTION_POINTERS] = len(original)
-      Settings.ALIASING_FUNCTION_POINTERS = 1 - Settings.ALIASING_FUNCTION_POINTERS
-      self.do_run(path_from_root('tests', 'cubescript'), '*\nTemp is 33\n9\n5\nhello, everyone\n*', main_file='command.cpp')
-      final = open('src.cpp.o.js').read()
-      results[Settings.ALIASING_FUNCTION_POINTERS] = len(final)
-      open('original.js', 'w').write(original)
-      print results
-      assert results[1] < 0.99*results[0]
-      assert ' & 3]()' in original, 'small function table exists'
-      assert ' & 3]()' not in final, 'small function table does not exist'
-      assert ' & 255]()' not in original, 'big function table does not exist'
-      assert ' & 255]()' in final, 'big function table exists'
-
   def test_simd(self):
     if Settings.USE_TYPED_ARRAYS != 2: return self.skip('needs ta2')
     if Settings.ASM_JS: Settings.ASM_JS = 2 # does not validate
@@ -4721,7 +4714,7 @@ return malloc(size);
     self.do_run_from_file(src, output)
 
   def test_gcc_unmangler(self):
-    if os.environ.get('EMCC_FAST_COMPILER') != '1': Settings.NAMED_GLOBALS = 1 # test coverage for this; fastcomp never names globals
+    if os.environ.get('EMCC_FAST_COMPILER') == '0': Settings.NAMED_GLOBALS = 1 # test coverage for this; fastcomp never names globals
 
     Building.COMPILER_TEST_OPTS += ['-I' + path_from_root('third_party'), '-Wno-warn-absolute-paths']
 
@@ -4892,7 +4885,7 @@ def process(filename):
       test()
 
       assert 'asm2g' in test_modes
-      if self.run_name == 'asm2g' and not use_cmake and os.environ.get('EMCC_FAST_COMPILER') != '1':
+      if self.run_name == 'asm2g' and not use_cmake and os.environ.get('EMCC_FAST_COMPILER') == '0':
         # Test forced alignment
         print >> sys.stderr, 'testing FORCE_ALIGNED_MEMORY'
         old = open('src.cpp.o.js').read()
@@ -5125,7 +5118,7 @@ def process(filename):
       for name in glob.glob(path_from_root('tests', 'cases', '*.ll')):
         shortname = name.replace('.ll', '')
         if '' not in shortname: continue
-        if os.environ.get('EMCC_FAST_COMPILER') == '1' and os.path.basename(shortname) in [
+        if os.environ.get('EMCC_FAST_COMPILER') != '0' and os.path.basename(shortname) in [
           'structparam', 'extendedprecision', 'issue_39', 'emptystruct', 'phinonexist', 'quotedlabel', 'oob_ta2', 'phientryimplicit', 'phiself', 'invokebitcast', 'funcptr', # invalid ir
           'structphiparam', 'callwithstructural_ta2', 'callwithstructural64_ta2', 'structinparam', # pnacl limitations in ExpandStructRegs
           '2xi40', # pnacl limitations in ExpandGetElementPtr
@@ -5141,7 +5134,7 @@ def process(filename):
         if '_le32' in shortname and not self.is_le32():
           print self.skip('case "%s" not relevant for non-le32 target' % shortname)
           continue
-        if '_fastcomp' in shortname and not os.environ.get('EMCC_FAST_COMPILER') == '1':
+        if '_fastcomp' in shortname and not os.environ.get('EMCC_FAST_COMPILER') != '0':
           print self.skip('case "%s" not relevant for non-fastcomp' % shortname)
           continue
         self.emcc_args = emcc_args
@@ -5180,7 +5173,7 @@ def process(filename):
       for name in glob.glob(path_from_root('tests', 'fuzz', '*.c')) + glob.glob(path_from_root('tests', 'fuzz', '*.cpp')):
         #if os.path.basename(name) != '4.c': continue
         if 'newfail' in name: continue
-        if os.path.basename(name) == '18.cpp' and not os.environ.get('EMCC_FAST_COMPILER') == '1': continue # works only in fastcomp
+        if os.path.basename(name) == '18.cpp' and not os.environ.get('EMCC_FAST_COMPILER') != '0': continue # works only in fastcomp
 
         print name
         self.do_run(open(path_from_root('tests', 'fuzz', name)).read(),
@@ -5420,7 +5413,7 @@ def process(filename):
 
   def test_asm_pgo(self):
     if not Settings.ASM_JS: return self.skip('this is a test for PGO for asm (NB: not *in* asm)')
-    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('todo in fastcomp')
+    if os.environ.get('EMCC_FAST_COMPILER') != '0': return self.skip('todo in fastcomp')
 
     src = open(path_from_root('tests', 'hello_libcxx.cpp')).read()
     output = 'hello, world!'
@@ -5540,7 +5533,7 @@ def process(filename):
 
   def test_embind(self):
     if self.emcc_args is None: return self.skip('requires emcc')
-    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('todo in fastcomp')
+    if os.environ.get('EMCC_FAST_COMPILER') != '0': return self.skip('todo in fastcomp')
     Building.COMPILER_TEST_OPTS += ['--bind']
 
     src = r'''
@@ -5563,7 +5556,7 @@ def process(filename):
 
   def test_embind_2(self):
     if self.emcc_args is None: return self.skip('requires emcc')
-    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('todo in fastcomp')
+    if os.environ.get('EMCC_FAST_COMPILER') != '0': return self.skip('todo in fastcomp')
     Building.COMPILER_TEST_OPTS += ['--bind', '--post-js', 'post.js']
     open('post.js', 'w').write('''
       Module.print('lerp ' + Module.lerp(1, 2, 0.66) + '.');
@@ -5637,8 +5630,6 @@ def process(filename):
 
       # Way 2: use CppHeaderParser
 
-      Settings.RUNTIME_TYPE_INFO = 1
-
       header = '''
         #include <stdio.h>
 
@@ -5879,6 +5870,8 @@ def process(filename):
       self.do_run(src, '|hello|43|world|41|', post_build=post)
 
   def test_typeinfo(self):
+    if os.environ.get('EMCC_FAST_COMPILER') != '0': return self.skip('fastcomp does not support RUNTIME_TYPE_INFO')
+
     if self.emcc_args is not None and self.emcc_args != []: return self.skip('full LLVM opts optimize out all the code that uses the type')
 
     Settings.RUNTIME_TYPE_INFO = 1
@@ -6397,7 +6390,7 @@ def process(filename):
 
   def test_minmax(self):
     if self.emcc_args == None: return self.skip('needs emcc')
-    if os.environ.get('EMCC_FAST_COMPILER') != '1': return self.skip('this test will not pass in the old compiler')
+    if os.environ.get('EMCC_FAST_COMPILER') == '0': return self.skip('this test will not pass in the old compiler')
     self.do_run(open(path_from_root('tests', 'test_minmax.c')).read(), 'NAN != NAN\nSuccess!')
 
   def test_locale(self):
@@ -6460,6 +6453,7 @@ def make_run(fullname, name=-1, compiler=-1, embetter=0, quantum_size=0,
       return
 
     # TODO: Move much of these to a init() function in shared.py, and reuse that
+    Settings.ASM_JS = 0
     Settings.USE_TYPED_ARRAYS = typed_arrays
     Settings.INVOKE_RUN = 1
     Settings.RELOOP = 0 # we only do them in the "o2" pass
@@ -6487,27 +6481,19 @@ def make_run(fullname, name=-1, compiler=-1, embetter=0, quantum_size=0,
 
   return TT
 
-# Make one run with the defaults
-default = make_run("default", compiler=CLANG, emcc_args=[] if os.environ.get('EMCC_FAST_COMPILER') != '1' else ['-s', 'ASM_JS=1'])
-
-# Make one run with -O1, with safe heap
-o1 = make_run("o1", compiler=CLANG, emcc_args=["-O1", "-s", "ASM_JS=0", "-s", "SAFE_HEAP=1"])
-
-# Make one run with -O2, but without closure (we enable closure in specific tests, otherwise on everything it is too slow)
-o2 = make_run("o2", compiler=CLANG, emcc_args=["-O2", "-s", "ASM_JS=0", "-s", "JS_CHUNK_SIZE=1024"])
-
-# asm.js
+# Main test modes
+default = make_run("default", compiler=CLANG, emcc_args=[])
 asm1 = make_run("asm1", compiler=CLANG, emcc_args=["-O1"])
 asm2 = make_run("asm2", compiler=CLANG, emcc_args=["-O2"])
 asm3 = make_run("asm3", compiler=CLANG, emcc_args=["-O3"])
 asm2f = make_run("asm2f", compiler=CLANG, emcc_args=["-O2", "-s", "PRECISE_F32=1"])
-if os.environ.get('EMCC_FAST_COMPILER') == '1':
-  asm2g = make_run("asm2g", compiler=CLANG, emcc_args=["-O2", "-g", "-s", "ASSERTIONS=1", "--memory-init-file", "1", "-s", "SAFE_HEAP=1"])
-else:
-  asm2g = make_run("asm2g", compiler=CLANG, emcc_args=["-O2", "-g", "-s", "ASSERTIONS=1", "--memory-init-file", "1", "-s", "CHECK_HEAP_ALIGN=1"])
-asm2x86 = make_run("asm2x86", compiler=CLANG, emcc_args=["-O2", "-g", "-s", "CHECK_HEAP_ALIGN=1"], env={"EMCC_LLVM_TARGET": "i386-pc-linux-gnu"})
+asm2g = make_run("asm2g", compiler=CLANG, emcc_args=["-O2", "-g", "-s", "ASSERTIONS=1", "--memory-init-file", "1", "-s", "SAFE_HEAP=1"])
+
+# Legacy test modes - 
+slow2 = make_run("slow2", compiler=CLANG, emcc_args=["-O2", "-s", "ASM_JS=0"], env={"EMCC_FAST_COMPILER": "0"})
+slow2asm = make_run("slow2asm", compiler=CLANG, emcc_args=["-O2"], env={"EMCC_FAST_COMPILER": "0"})
 
-# Make custom runs with various options
+# Legacy test modes - very old
 for compiler, quantum, embetter, typed_arrays in [
   (CLANG, 4, 0, 0),
   (CLANG, 4, 1, 1),
@@ -6515,6 +6501,6 @@ for compiler, quantum, embetter, typed_arrays in [
   fullname = 's_0_%d%s%s' % (
     embetter, '' if quantum == 4 else '_q' + str(quantum), '' if typed_arrays in [0, 1] else '_t' + str(typed_arrays)
   )
-  locals()[fullname] = make_run(fullname, fullname, compiler, embetter, quantum, typed_arrays)
+  locals()[fullname] = make_run(fullname, fullname, compiler, embetter, quantum, typed_arrays, env={"EMCC_FAST_COMPILER": "0"})
 
 del T # T is just a shape for the specific subclasses, we don't test it itself
diff --git a/tests/test_other.py b/tests/test_other.py
index 80461972..69f8d5c0 100644
--- a/tests/test_other.py
+++ b/tests/test_other.py
@@ -1,7 +1,7 @@
 import multiprocessing, os, re, shutil, subprocess, sys
 import tools.shared
 from tools.shared import *
-from runner import RunnerCore, path_from_root, get_bullet_library
+from runner import RunnerCore, path_from_root, get_bullet_library, nonfastcomp
 
 class other(RunnerCore):
   def get_zlib_library(self):
@@ -207,7 +207,7 @@ Options that are modified or new in %s include:
       ]:
         print params, text
         self.clear()
-        if os.environ.get('EMCC_FAST_COMPILER') == '1' and ['disable typed arrays', 'typed arrays 1 selected']: continue
+        if os.environ.get('EMCC_FAST_COMPILER') != '0' and ['disable typed arrays', 'typed arrays 1 selected']: continue
         output = Popen([PYTHON, compiler, path_from_root('tests', 'hello_world_loop.cpp'), '-o', 'a.out.js'] + params, stdout=PIPE, stderr=PIPE).communicate()
         assert len(output[0]) == 0, output[0]
         assert os.path.exists('a.out.js'), '\n'.join(output)
@@ -277,6 +277,9 @@ f.close()
     # TODO: test normal project linking, static and dynamic: get_library should not need to be told what to link!
     # TODO: deprecate llvm optimizations, dlmalloc, etc. in emscripten.py.
 
+  def test_emcc_nonfastcomp(self):
+    nonfastcomp(self.test_emcc)
+
   def test_cmake(self):
     # Test all supported generators.
     if WINDOWS:
@@ -451,48 +454,48 @@ f.close()
     self.assertContained('hello, world!', run_js(os.path.join(self.get_dir(), 'a.out.js')))
 
   def test_unaligned_memory(self):
-    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('todo in fastcomp')
-
-    open(os.path.join(self.get_dir(), 'test.cpp'), 'w').write(r'''
-      #include <stdio.h>
-      #include <stdarg.h>
+    def test():
+      open(os.path.join(self.get_dir(), 'test.cpp'), 'w').write(r'''
+        #include <stdio.h>
+        #include <stdarg.h>
 
-      typedef unsigned char   Bit8u;
-      typedef unsigned short  Bit16u;
-      typedef unsigned int    Bit32u;
+        typedef unsigned char   Bit8u;
+        typedef unsigned short  Bit16u;
+        typedef unsigned int    Bit32u;
 
-      int main()
-      {
-        va_list argp;
-        va_arg(argp, char *); // check for compilation error, #1705
+        int main()
+        {
+          va_list argp;
+          va_arg(argp, char *); // check for compilation error, #1705
 
-        Bit8u data[4] = {0x01,0x23,0x45,0x67};
+          Bit8u data[4] = {0x01,0x23,0x45,0x67};
 
-        printf("data: %x\n", *(Bit32u*)data);
-        printf("data[0,1] 16bit: %x\n", *(Bit16u*)data);
-        printf("data[1,2] 16bit: %x\n", *(Bit16u*)(data+1));
-      }
-    ''')
-    Popen([PYTHON, EMCC, os.path.join(self.get_dir(), 'test.cpp'), '-s', 'UNALIGNED_MEMORY=1']).communicate()
-    self.assertContained('data: 67452301\ndata[0,1] 16bit: 2301\ndata[1,2] 16bit: 4523', run_js(os.path.join(self.get_dir(), 'a.out.js')))
+          printf("data: %x\n", *(Bit32u*)data);
+          printf("data[0,1] 16bit: %x\n", *(Bit16u*)data);
+          printf("data[1,2] 16bit: %x\n", *(Bit16u*)(data+1));
+        }
+      ''')
+      Popen([PYTHON, EMCC, os.path.join(self.get_dir(), 'test.cpp'), '-s', 'UNALIGNED_MEMORY=1']).communicate()
+      self.assertContained('data: 67452301\ndata[0,1] 16bit: 2301\ndata[1,2] 16bit: 4523', run_js(os.path.join(self.get_dir(), 'a.out.js')))
+    nonfastcomp(test)
 
   def test_unaligned_memory_2(self):
-    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('todo in fastcomp')
-
-    open(os.path.join(self.get_dir(), 'test.cpp'), 'w').write(r'''
-      #include <string>
-      #include <stdio.h>
+    def test():
+      open(os.path.join(self.get_dir(), 'test.cpp'), 'w').write(r'''
+        #include <string>
+        #include <stdio.h>
 
-      int main( int argc, char ** argv )
-      {
-          std::string testString( "Hello, World!" );
+        int main( int argc, char ** argv )
+        {
+            std::string testString( "Hello, World!" );
 
-          printf( "testString = %s\n", testString.c_str() );
-          return 0;
-      }
-      ''')
-    Popen([PYTHON, EMCC, os.path.join(self.get_dir(), 'test.cpp'), '-s', 'UNALIGNED_MEMORY=1']).communicate()
-    self.assertContained('testString = Hello, World!', run_js(os.path.join(self.get_dir(), 'a.out.js')))
+            printf( "testString = %s\n", testString.c_str() );
+            return 0;
+        }
+        ''')
+      Popen([PYTHON, EMCC, os.path.join(self.get_dir(), 'test.cpp'), '-s', 'UNALIGNED_MEMORY=1']).communicate()
+      self.assertContained('testString = Hello, World!', run_js(os.path.join(self.get_dir(), 'a.out.js')))
+    nonfastcomp(test)
 
   def test_asm_minify(self):
     def test(args):
@@ -542,7 +545,7 @@ f.close()
       self.assertContained(expected, run_js(self.in_dir('a.out.js'), stderr=PIPE, full_output=True))
       return open(self.in_dir('a.out.js')).read()
 
-    if os.environ.get('EMCC_FAST_COMPILER') != '1':
+    if os.environ.get('EMCC_FAST_COMPILER') == '0':
       test([], 'my func') # no asm, so casting func works
       test(['-O2'], 'abort', ['Casting potentially incompatible function pointer i32 ()* to void (...)*, for my_func',
                               'Incompatible function pointer casts are very dangerous with ASM_JS=1, you should investigate and correct these']) # asm, so failure
@@ -590,283 +593,285 @@ This pointer might make sense in another type signature: i: _my_func
     assert not os.path.exists('a.out') and not os.path.exists('a.exe'), 'Must not leave unneeded linker stubs'
 
   def test_static_link(self):
-    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('todo in fastcomp')
-
-    def test(name, header, main, side, expected, args=[], suffix='cpp', first=True):
-      print name
-      #t = main ; main = side ; side = t
-      original_main = main
-      original_side = side
-      if header: open(os.path.join(self.get_dir(), 'header.h'), 'w').write(header)
-      if type(main) == str:
-        open(os.path.join(self.get_dir(), 'main.' + suffix), 'w').write(main)
-        main = ['main.' + suffix]
-      if type(side) == str:
-        open(os.path.join(self.get_dir(), 'side.' + suffix), 'w').write(side)
-        side = ['side.' + suffix]
-      Popen([PYTHON, EMCC] + side + ['-o', 'side.js', '-s', 'SIDE_MODULE=1', '-O2'] + args).communicate()
-      # TODO: test with and without DISABLE_GL_EMULATION, check that file sizes change
-      Popen([PYTHON, EMCC] + main + ['-o', 'main.js', '-s', 'MAIN_MODULE=1', '-O2', '-s', 'DISABLE_GL_EMULATION=1'] + args).communicate()
-      Popen([PYTHON, EMLINK, 'main.js', 'side.js', 'together.js'], stdout=PIPE).communicate()
-      assert os.path.exists('together.js')
-      for engine in JS_ENGINES:
-        out = run_js('together.js', engine=engine, stderr=PIPE, full_output=True)
-        self.assertContained(expected, out)
-        if engine == SPIDERMONKEY_ENGINE: self.validate_asmjs(out)
-      if first:
-        shutil.copyfile('together.js', 'first.js')
-        test(name + ' (reverse)', header, original_side, original_main, expected, args, suffix, False) # test reverse order
-
-    # test a simple call from one module to another. only one has a string (and constant memory initialization for it)
-    test('basics', '', '''
-      #include <stdio.h>
-      extern int sidey();
-      int main() {
-        printf("other says %d.", sidey());
-        return 0;
-      }
-    ''', '''
-      int sidey() { return 11; }
-    ''', 'other says 11.')
-
-    # finalization of float variables should pass asm.js validation
-    test('floats', '', '''
-      #include <stdio.h>
-      extern float sidey();
-      int main() {
-        printf("other says %.2f.", sidey()+1);
-        return 0;
-      }
-    ''', '''
-      float sidey() { return 11.5; }
-    ''', 'other says 12.50')
+    def nonfc():
+      if os.environ.get('EMCC_FAST_COMPILER') != '0': return self.skip('todo in fastcomp')
+
+      def test(name, header, main, side, expected, args=[], suffix='cpp', first=True):
+        print name
+        #t = main ; main = side ; side = t
+        original_main = main
+        original_side = side
+        if header: open(os.path.join(self.get_dir(), 'header.h'), 'w').write(header)
+        if type(main) == str:
+          open(os.path.join(self.get_dir(), 'main.' + suffix), 'w').write(main)
+          main = ['main.' + suffix]
+        if type(side) == str:
+          open(os.path.join(self.get_dir(), 'side.' + suffix), 'w').write(side)
+          side = ['side.' + suffix]
+        Popen([PYTHON, EMCC] + side + ['-o', 'side.js', '-s', 'SIDE_MODULE=1', '-O2'] + args).communicate()
+        # TODO: test with and without DISABLE_GL_EMULATION, check that file sizes change
+        Popen([PYTHON, EMCC] + main + ['-o', 'main.js', '-s', 'MAIN_MODULE=1', '-O2', '-s', 'DISABLE_GL_EMULATION=1'] + args).communicate()
+        Popen([PYTHON, EMLINK, 'main.js', 'side.js', 'together.js'], stdout=PIPE).communicate()
+        assert os.path.exists('together.js')
+        for engine in JS_ENGINES:
+          out = run_js('together.js', engine=engine, stderr=PIPE, full_output=True)
+          self.assertContained(expected, out)
+          if engine == SPIDERMONKEY_ENGINE: self.validate_asmjs(out)
+        if first:
+          shutil.copyfile('together.js', 'first.js')
+          test(name + ' (reverse)', header, original_side, original_main, expected, args, suffix, False) # test reverse order
+
+      # test a simple call from one module to another. only one has a string (and constant memory initialization for it)
+      test('basics', '', '''
+        #include <stdio.h>
+        extern int sidey();
+        int main() {
+          printf("other says %d.", sidey());
+          return 0;
+        }
+      ''', '''
+        int sidey() { return 11; }
+      ''', 'other says 11.')
 
-    # memory initialization in both
-    test('multiple memory inits', '', r'''
-      #include <stdio.h>
-      extern void sidey();
-      int main() {
-        printf("hello from main\n");
-        sidey();
-        return 0;
-      }
-    ''', r'''
-      #include <stdio.h>
-      void sidey() { printf("hello from side\n"); }
-    ''', 'hello from main\nhello from side\n')
+      # finalization of float variables should pass asm.js validation
+      test('floats', '', '''
+        #include <stdio.h>
+        extern float sidey();
+        int main() {
+          printf("other says %.2f.", sidey()+1);
+          return 0;
+        }
+      ''', '''
+        float sidey() { return 11.5; }
+      ''', 'other says 12.50')
 
-    # function pointers
-    test('fp1', 'typedef void (*voidfunc)();', r'''
-      #include <stdio.h>
-      #include "header.h"
-      voidfunc sidey(voidfunc f);
-      void a() { printf("hello from funcptr\n"); }
-      int main() {
-        sidey(a)();
-        return 0;
-      }
-    ''', '''
-      #include "header.h"
-      voidfunc sidey(voidfunc f) { return f; }
-    ''', 'hello from funcptr\n')
+      # memory initialization in both
+      test('multiple memory inits', '', r'''
+        #include <stdio.h>
+        extern void sidey();
+        int main() {
+          printf("hello from main\n");
+          sidey();
+          return 0;
+        }
+      ''', r'''
+        #include <stdio.h>
+        void sidey() { printf("hello from side\n"); }
+      ''', 'hello from main\nhello from side\n')
 
-    # function pointers with 'return' in the name
-    test('fp2', 'typedef void (*voidfunc)();', r'''
-      #include <stdio.h>
-      #include "header.h"
-      int sidey(voidfunc f);
-      void areturn0() { printf("hello 0\n"); }
-      void areturn1() { printf("hello 1\n"); }
-      void areturn2() { printf("hello 2\n"); }
-      int main(int argc, char **argv) {
-        voidfunc table[3] = { areturn0, areturn1, areturn2 };
-        table[sidey(NULL)]();
-        return 0;
-      }
-    ''', '''
-      #include "header.h"
-      int sidey(voidfunc f) { if (f) f(); return 1; }
-    ''', 'hello 1\n')
+      # function pointers
+      test('fp1', 'typedef void (*voidfunc)();', r'''
+        #include <stdio.h>
+        #include "header.h"
+        voidfunc sidey(voidfunc f);
+        void a() { printf("hello from funcptr\n"); }
+        int main() {
+          sidey(a)();
+          return 0;
+        }
+      ''', '''
+        #include "header.h"
+        voidfunc sidey(voidfunc f) { return f; }
+      ''', 'hello from funcptr\n')
 
-    # Global initializer
-    test('global init', '', r'''
-      #include <stdio.h>
-      struct Class {
-        Class() { printf("a new Class\n"); }
-      };
-      static Class c;
-      int main() {
-        return 0;
-      }
-    ''', r'''
-      void nothing() {}
-    ''', 'a new Class\n')
+      # function pointers with 'return' in the name
+      test('fp2', 'typedef void (*voidfunc)();', r'''
+        #include <stdio.h>
+        #include "header.h"
+        int sidey(voidfunc f);
+        void areturn0() { printf("hello 0\n"); }
+        void areturn1() { printf("hello 1\n"); }
+        void areturn2() { printf("hello 2\n"); }
+        int main(int argc, char **argv) {
+          voidfunc table[3] = { areturn0, areturn1, areturn2 };
+          table[sidey(NULL)]();
+          return 0;
+        }
+      ''', '''
+        #include "header.h"
+        int sidey(voidfunc f) { if (f) f(); return 1; }
+      ''', 'hello 1\n')
 
-    # Multiple global initializers (LLVM generates overlapping names for them)
-    test('global inits', r'''
-      #include <stdio.h>
-      struct Class {
-        Class(const char *name) { printf("new %s\n", name); }
-      };
-    ''', r'''
-      #include "header.h"
-      static Class c("main");
-      int main() {
-        return 0;
-      }
-    ''', r'''
-      #include "header.h"
-      static Class c("side");
-    ''', ['new main\nnew side\n', 'new side\nnew main\n'])
+      # Global initializer
+      test('global init', '', r'''
+        #include <stdio.h>
+        struct Class {
+          Class() { printf("a new Class\n"); }
+        };
+        static Class c;
+        int main() {
+          return 0;
+        }
+      ''', r'''
+        void nothing() {}
+      ''', 'a new Class\n')
 
-    # Class code used across modules
-    test('codecall', r'''
-      #include <stdio.h>
-      struct Class {
-        Class(const char *name);
-      };
-    ''', r'''
-      #include "header.h"
-      int main() {
-        Class c("main");
-        return 0;
-      }
-    ''', r'''
-      #include "header.h"
-      Class::Class(const char *name) { printf("new %s\n", name); }
-    ''', ['new main\n'])
-
-    # malloc usage in both modules
-    test('malloc', r'''
-      #include <stdlib.h>
-      #include <string.h>
-      char *side(const char *data);
-    ''', r'''
-      #include <stdio.h>
-      #include "header.h"
-      int main() {
-        char *temp = side("hello through side\n");
-        char *ret = (char*)malloc(strlen(temp)+1);
-        strcpy(ret, temp);
-        temp[1] = 'x';
-        puts(ret);
-        return 0;
-      }
-    ''', r'''
-      #include "header.h"
-      char *side(const char *data) {
-        char *ret = (char*)malloc(strlen(data)+1);
-        strcpy(ret, data);
-        return ret;
-      }
-    ''', ['hello through side\n'])
+      # Multiple global initializers (LLVM generates overlapping names for them)
+      test('global inits', r'''
+        #include <stdio.h>
+        struct Class {
+          Class(const char *name) { printf("new %s\n", name); }
+        };
+      ''', r'''
+        #include "header.h"
+        static Class c("main");
+        int main() {
+          return 0;
+        }
+      ''', r'''
+        #include "header.h"
+        static Class c("side");
+      ''', ['new main\nnew side\n', 'new side\nnew main\n'])
 
-    # js library call
-    open('lib.js', 'w').write(r'''
-      mergeInto(LibraryManager.library, {
-        test_lib_func: function(x) {
-          return x + 17.2;
+      # Class code used across modules
+      test('codecall', r'''
+        #include <stdio.h>
+        struct Class {
+          Class(const char *name);
+        };
+      ''', r'''
+        #include "header.h"
+        int main() {
+          Class c("main");
+          return 0;
         }
-      });
-    ''')
-    test('js-lib', 'extern "C" { extern double test_lib_func(int input); }', r'''
-      #include <stdio.h>
-      #include "header.h"
-      extern double sidey();
-      int main2() { return 11; }
-      int main() {
-        int input = sidey();
-        double temp = test_lib_func(input);
-        printf("other says %.2f\n", temp);
-        printf("more: %.5f, %d\n", temp, input);
-        return 0;
-      }
-    ''', r'''
-      #include <stdio.h>
-      #include "header.h"
-      extern int main2();
-      double sidey() {
-        int temp = main2();
-        printf("main2 sed: %d\n", temp);
-        printf("main2 sed: %u, %c\n", temp, temp/2);
-        return test_lib_func(temp);
-      }
-    ''', 'other says 45.2', ['--js-library', 'lib.js'])
+      ''', r'''
+        #include "header.h"
+        Class::Class(const char *name) { printf("new %s\n", name); }
+      ''', ['new main\n'])
 
-    # libc usage in one modules. must force libc inclusion in the main module if that isn't the one using mallinfo()
-    try:
-      os.environ['EMCC_FORCE_STDLIBS'] = 'libc'
-      test('malloc-1', r'''
+      # malloc usage in both modules
+      test('malloc', r'''
+        #include <stdlib.h>
         #include <string.h>
-        int side();
+        char *side(const char *data);
       ''', r'''
         #include <stdio.h>
         #include "header.h"
         int main() {
-          printf("|%d|\n", side());
+          char *temp = side("hello through side\n");
+          char *ret = (char*)malloc(strlen(temp)+1);
+          strcpy(ret, temp);
+          temp[1] = 'x';
+          puts(ret);
           return 0;
         }
       ''', r'''
-        #include <stdlib.h>
-        #include <malloc.h>
         #include "header.h"
-        int side() {
-          struct mallinfo m = mallinfo();
-          return m.arena > 1;
+        char *side(const char *data) {
+          char *ret = (char*)malloc(strlen(data)+1);
+          strcpy(ret, data);
+          return ret;
         }
-      ''', ['|1|\n'])
-    finally:
-      del os.environ['EMCC_FORCE_STDLIBS']
-
-    # iostream usage in one and std::string in both
-    test('iostream', r'''
-      #include <iostream>
-      #include <string>
-      std::string side();
-    ''', r'''
-      #include "header.h"
-      int main() {
-        std::cout << "hello from main " << side() << std::endl;
-        return 0;
-      }
-    ''', r'''
-      #include "header.h"
-      std::string side() { return "and hello from side"; }
-    ''', ['hello from main and hello from side\n'])
-
-    # followup to iostream test: a second linking
-    print 'second linking of a linking output'
-    open('moar.cpp', 'w').write(r'''
-      #include <iostream>
-      struct Moar {
-        Moar() { std::cout << "moar!" << std::endl; }
-      };
-      Moar m;
-    ''')
-    Popen([PYTHON, EMCC, 'moar.cpp', '-o', 'moar.js', '-s', 'SIDE_MODULE=1', '-O2']).communicate()
-    Popen([PYTHON, EMLINK, 'together.js', 'moar.js', 'triple.js'], stdout=PIPE).communicate()
-    assert os.path.exists('triple.js')
-    for engine in JS_ENGINES:
-      out = run_js('triple.js', engine=engine, stderr=PIPE, full_output=True)
-      self.assertContained('moar!\nhello from main and hello from side\n', out)
-      if engine == SPIDERMONKEY_ENGINE: self.validate_asmjs(out)
-
-    # zlib compression library. tests function pointers in initializers and many other things
-    test('zlib', '', open(path_from_root('tests', 'zlib', 'example.c'), 'r').read(), 
-                     self.get_zlib_library(),
-                     open(path_from_root('tests', 'zlib', 'ref.txt'), 'r').read(),
-                     args=['-I' + path_from_root('tests', 'zlib')], suffix='c')
-
-    use_cmake = WINDOWS
-    bullet_library = get_bullet_library(self, use_cmake)
-
-    # bullet physics engine. tests all the things
-    test('bullet', '', open(path_from_root('tests', 'bullet', 'Demos', 'HelloWorld', 'HelloWorld.cpp'), 'r').read(), 
-         bullet_library,
-         [open(path_from_root('tests', 'bullet', 'output.txt'), 'r').read(), # different roundings
-          open(path_from_root('tests', 'bullet', 'output2.txt'), 'r').read(),
-          open(path_from_root('tests', 'bullet', 'output3.txt'), 'r').read()],
-         args=['-I' + path_from_root('tests', 'bullet', 'src')])
+      ''', ['hello through side\n'])
+
+      # js library call
+      open('lib.js', 'w').write(r'''
+        mergeInto(LibraryManager.library, {
+          test_lib_func: function(x) {
+            return x + 17.2;
+          }
+        });
+      ''')
+      test('js-lib', 'extern "C" { extern double test_lib_func(int input); }', r'''
+        #include <stdio.h>
+        #include "header.h"
+        extern double sidey();
+        int main2() { return 11; }
+        int main() {
+          int input = sidey();
+          double temp = test_lib_func(input);
+          printf("other says %.2f\n", temp);
+          printf("more: %.5f, %d\n", temp, input);
+          return 0;
+        }
+      ''', r'''
+        #include <stdio.h>
+        #include "header.h"
+        extern int main2();
+        double sidey() {
+          int temp = main2();
+          printf("main2 sed: %d\n", temp);
+          printf("main2 sed: %u, %c\n", temp, temp/2);
+          return test_lib_func(temp);
+        }
+      ''', 'other says 45.2', ['--js-library', 'lib.js'])
+
+      # libc usage in one modules. must force libc inclusion in the main module if that isn't the one using mallinfo()
+      try:
+        os.environ['EMCC_FORCE_STDLIBS'] = 'libc'
+        test('malloc-1', r'''
+          #include <string.h>
+          int side();
+        ''', r'''
+          #include <stdio.h>
+          #include "header.h"
+          int main() {
+            printf("|%d|\n", side());
+            return 0;
+          }
+        ''', r'''
+          #include <stdlib.h>
+          #include <malloc.h>
+          #include "header.h"
+          int side() {
+            struct mallinfo m = mallinfo();
+            return m.arena > 1;
+          }
+        ''', ['|1|\n'])
+      finally:
+        del os.environ['EMCC_FORCE_STDLIBS']
+
+      # iostream usage in one and std::string in both
+      test('iostream', r'''
+        #include <iostream>
+        #include <string>
+        std::string side();
+      ''', r'''
+        #include "header.h"
+        int main() {
+          std::cout << "hello from main " << side() << std::endl;
+          return 0;
+        }
+      ''', r'''
+        #include "header.h"
+        std::string side() { return "and hello from side"; }
+      ''', ['hello from main and hello from side\n'])
+
+      # followup to iostream test: a second linking
+      print 'second linking of a linking output'
+      open('moar.cpp', 'w').write(r'''
+        #include <iostream>
+        struct Moar {
+          Moar() { std::cout << "moar!" << std::endl; }
+        };
+        Moar m;
+      ''')
+      Popen([PYTHON, EMCC, 'moar.cpp', '-o', 'moar.js', '-s', 'SIDE_MODULE=1', '-O2']).communicate()
+      Popen([PYTHON, EMLINK, 'together.js', 'moar.js', 'triple.js'], stdout=PIPE).communicate()
+      assert os.path.exists('triple.js')
+      for engine in JS_ENGINES:
+        out = run_js('triple.js', engine=engine, stderr=PIPE, full_output=True)
+        self.assertContained('moar!\nhello from main and hello from side\n', out)
+        if engine == SPIDERMONKEY_ENGINE: self.validate_asmjs(out)
+
+      # zlib compression library. tests function pointers in initializers and many other things
+      test('zlib', '', open(path_from_root('tests', 'zlib', 'example.c'), 'r').read(), 
+                       self.get_zlib_library(),
+                       open(path_from_root('tests', 'zlib', 'ref.txt'), 'r').read(),
+                       args=['-I' + path_from_root('tests', 'zlib')], suffix='c')
+
+      use_cmake = WINDOWS
+      bullet_library = get_bullet_library(self, use_cmake)
+
+      # bullet physics engine. tests all the things
+      test('bullet', '', open(path_from_root('tests', 'bullet', 'Demos', 'HelloWorld', 'HelloWorld.cpp'), 'r').read(), 
+           bullet_library,
+           [open(path_from_root('tests', 'bullet', 'output.txt'), 'r').read(), # different roundings
+            open(path_from_root('tests', 'bullet', 'output2.txt'), 'r').read(),
+            open(path_from_root('tests', 'bullet', 'output3.txt'), 'r').read()],
+           args=['-I' + path_from_root('tests', 'bullet', 'src')])
+    nonfastcomp(nonfc)
 
   def test_outline(self):
     def test(name, src, libs, expected, expected_ranges, args=[], suffix='cpp'):
@@ -918,7 +923,7 @@ This pointer might make sense in another type signature: i: _my_func
          500: (250, 500),
         1000: (230, 1000),
         2000: (380, 2000),
-        5000: (800, 5000),
+        5000: (500, 5000),
            0: (1500, 5000)
       }),
       (['-O2'], {
@@ -1817,26 +1822,28 @@ This pointer might make sense in another type signature: i: _my_func
       assert 'error' not in err, 'Unexpected stderr: ' + err
 
   def test_chunking(self):
-    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('not relevant for fastcomp, only checks js compiler chunking')
-    if os.environ.get('EMCC_DEBUG'): return self.skip('cannot run in debug mode')
-    if os.environ.get('EMCC_CORES'): return self.skip('cannot run if cores are altered')
-    if multiprocessing.cpu_count() < 2: return self.skip('need multiple cores')
-    try:
-      os.environ['EMCC_DEBUG'] = '1'
-      os.environ['EMCC_CORES'] = '2' # standardize over machines
-      for asm, linkable, chunks in [
-          (0, 0, 2), (0, 1, 2),
-          (1, 0, 2), (1, 1, 2)
-        ]:
-        print asm, linkable, chunks
-        output, err = Popen([PYTHON, EMCC, path_from_root('tests', 'hello_libcxx.cpp'), '-O1', '-s', 'LINKABLE=%d' % linkable, '-s', 'ASM_JS=%d' % asm] + (['-O2'] if asm else []), stdout=PIPE, stderr=PIPE).communicate()
-        ok = False
-        for c in range(chunks, chunks+2):
-          ok = ok or ('phase 2 working on %d chunks' % c in err)
-        assert ok, err
-    finally:
-      del os.environ['EMCC_DEBUG']
-      del os.environ['EMCC_CORES']
+    def nonfc():
+      if os.environ.get('EMCC_FAST_COMPILER') != '0': return self.skip('not relevant for fastcomp, only checks js compiler chunking')
+      if os.environ.get('EMCC_DEBUG'): return self.skip('cannot run in debug mode')
+      if os.environ.get('EMCC_CORES'): return self.skip('cannot run if cores are altered')
+      if multiprocessing.cpu_count() < 2: return self.skip('need multiple cores')
+      try:
+        os.environ['EMCC_DEBUG'] = '1'
+        os.environ['EMCC_CORES'] = '2' # standardize over machines
+        for asm, linkable, chunks in [
+            (0, 0, 2), (0, 1, 2),
+            (1, 0, 2), (1, 1, 2)
+          ]:
+          print asm, linkable, chunks
+          output, err = Popen([PYTHON, EMCC, path_from_root('tests', 'hello_libcxx.cpp'), '-O1', '-s', 'LINKABLE=%d' % linkable, '-s', 'ASM_JS=%d' % asm] + (['-O2'] if asm else []), stdout=PIPE, stderr=PIPE).communicate()
+          ok = False
+          for c in range(chunks, chunks+2):
+            ok = ok or ('phase 2 working on %d chunks' % c in err)
+          assert ok, err
+      finally:
+        del os.environ['EMCC_DEBUG']
+        del os.environ['EMCC_CORES']
+    nonfastcomp(nonfc)
 
   def test_debuginfo(self):
     if os.environ.get('EMCC_DEBUG'): return self.skip('cannot run in debug mode')
@@ -1868,23 +1875,25 @@ This pointer might make sense in another type signature: i: _my_func
     assert 'If you see this - the world is all right!' in output
 
   def test_embind(self):
-    if os.environ.get('EMCC_FAST_COMPILER') == '1': return self.skip('todo in fastcomp')
-    for args, fail in [
-      ([], True), # without --bind, we fail
-      (['--bind'], False),
-      (['--bind', '-O1'], False),
-      (['--bind', '-O2'], False),
-      (['--bind', '-O1', '-s', 'ASM_JS=0'], False),
-      (['--bind', '-O2', '-s', 'ASM_JS=0'], False)
-    ]:
-      print args, fail
-      self.clear()
-      try_delete(self.in_dir('a.out.js'))
-      Popen([PYTHON, EMCC, path_from_root('tests', 'embind', 'embind_test.cpp'), '--post-js', path_from_root('tests', 'embind', 'underscore-1.4.2.js'), '--post-js', path_from_root('tests', 'embind', 'imvu_test_adapter.js'), '--post-js', path_from_root('tests', 'embind', 'embind.test.js')] + args, stderr=PIPE if fail else None).communicate()
-      assert os.path.exists(self.in_dir('a.out.js')) == (not fail)
-      if not fail:
-        output = run_js(self.in_dir('a.out.js'), stdout=PIPE, stderr=PIPE, full_output=True)
-        assert "FAIL" not in output, output
+    def nonfc():
+      if os.environ.get('EMCC_FAST_COMPILER') != '0': return self.skip('todo in fastcomp')
+      for args, fail in [
+        ([], True), # without --bind, we fail
+        (['--bind'], False),
+        (['--bind', '-O1'], False),
+        (['--bind', '-O2'], False),
+        (['--bind', '-O1', '-s', 'ASM_JS=0'], False),
+        (['--bind', '-O2', '-s', 'ASM_JS=0'], False)
+      ]:
+        print args, fail
+        self.clear()
+        try_delete(self.in_dir('a.out.js'))
+        Popen([PYTHON, EMCC, path_from_root('tests', 'embind', 'embind_test.cpp'), '--post-js', path_from_root('tests', 'embind', 'underscore-1.4.2.js'), '--post-js', path_from_root('tests', 'embind', 'imvu_test_adapter.js'), '--post-js', path_from_root('tests', 'embind', 'embind.test.js')] + args, stderr=PIPE if fail else None).communicate()
+        assert os.path.exists(self.in_dir('a.out.js')) == (not fail)
+        if not fail:
+          output = run_js(self.in_dir('a.out.js'), stdout=PIPE, stderr=PIPE, full_output=True)
+          assert "FAIL" not in output, output
+    nonfastcomp(nonfc)
 
   def test_llvm_nativizer(self):
     try:
@@ -2362,7 +2371,7 @@ int main() {
     assert '*** PCH/Modules Loaded:\nModule: header.h.gch' not in err[1], err[1]
 
   def test_warn_unaligned(self):
-    if os.environ.get('EMCC_FAST_COMPILER') != '1': return self.skip('need fastcomp')
+    if os.environ.get('EMCC_FAST_COMPILER') == '0': return self.skip('need fastcomp')
     open('src.cpp', 'w').write(r'''
 #include <stdio.h>
 static const double grid[4][2] = {{-3 / 3., -1 / 3.},
diff --git a/tests/test_sanity.py b/tests/test_sanity.py
index 894f2192..5713c99c 100644
--- a/tests/test_sanity.py
+++ b/tests/test_sanity.py
@@ -196,9 +196,10 @@ class sanity(RunnerCore):
       del os.environ['EM_IGNORE_SANITY']
 
   def test_llvm_fastcomp(self):
-    if os.environ.get('EMCC_FAST_COMPILER') != '1': return self.skip('not using fastcomp')
+    assert os.environ.get('EMCC_FAST_COMPILER') != '0', 'must be using fastcomp to test fastcomp'
 
     WARNING = 'fastcomp in use, but LLVM has not been built with the JavaScript backend as a target'
+    WARNING2 = 'you can fall back to the older (pre-fastcomp) compiler core, although that is not recommended, see https://github.com/kripken/emscripten/wiki/LLVM-Backend'
 
     restore()
 
@@ -206,6 +207,7 @@ class sanity(RunnerCore):
     assert check_fastcomp()
     output = self.check_working(EMCC)
     assert WARNING not in output, output
+    assert WARNING2 not in output, output
 
     # Fake incorrect llc output, no mention of js backend
     restore()
@@ -222,6 +224,11 @@ class sanity(RunnerCore):
     f.close()
     os.chmod(path_from_root('tests', 'fake', 'llc'), stat.S_IREAD | stat.S_IWRITE | stat.S_IEXEC)
     output = self.check_working(EMCC, WARNING)
+    output = self.check_working(EMCC, WARNING2)
+
+    restore()
+
+    self.check_working([EMCC, 'tests/hello_world.cpp', '-s', 'INIT_HEAP=1'], '''Compiler settings are incompatible with fastcomp. You can fall back to the older compiler core, although that is not recommended, see https://github.com/kripken/emscripten/wiki/LLVM-Backend''')
 
   def test_node(self):
     NODE_WARNING = 'node version appears too old'
@@ -446,111 +453,34 @@ fi
     try_delete(CANONICAL_TEMP_DIR)
 
   def test_relooper(self):
-    RELOOPER = Cache.get_path('relooper.js')
-
-    restore()
-    for phase in range(2): # 0: we wipe the relooper dir. 1: we have it, so should just update
-      if phase == 0: Cache.erase()
-      try_delete(RELOOPER)
-
-      for i in range(4):
-        print >> sys.stderr, phase, i
-        opt = min(i, 2)
-        try_delete('a.out.js')
-        output = Popen([PYTHON, EMCC, path_from_root('tests', 'hello_world_loop.cpp'), '-O' + str(opt), '-g'],
-                       stdout=PIPE, stderr=PIPE).communicate()
-        self.assertContained('hello, world!', run_js('a.out.js'))
-        output = '\n'.join(output)
-        assert ('bootstrapping relooper succeeded' in output) == (i == 1), 'only bootstrap on first O2: ' + output
-        assert os.path.exists(RELOOPER) == (i >= 1), 'have relooper on O2: ' + output
-        src = open('a.out.js').read()
-        main = src.split('function _main()')[1].split('\n}\n')[0]
-        assert ('while (1) {' in main or 'while(1){' in main or 'while(1) {' in main or '} while ($' in main or '}while($' in main) == (i >= 1), 'reloop code on O2: ' + main
-        assert ('switch' not in main) == (i >= 1), 'reloop code on O2: ' + main
-
-  def test_jcache(self):
-    PRE_LOAD_MSG = 'loading pre from jcache'
-    PRE_SAVE_MSG = 'saving pre to jcache'
-    FUNC_CHUNKS_LOAD_MSG = ' funcchunks from jcache'
-    FUNC_CHUNKS_SAVE_MSG = ' funcchunks to jcache'
-    JSFUNC_CHUNKS_LOAD_MSG = 'jsfuncchunks from jcache'
-    JSFUNC_CHUNKS_SAVE_MSG = 'jsfuncchunks to jcache'
-
-    restore()
-    Cache.erase()
+    assert os.environ.get('EMCC_FAST_COMPILER') is None
 
     try:
-      os.environ['EMCC_DEBUG'] = '1'
-      os.environ['EMCC_JSOPT_MIN_CHUNK_SIZE'] = str(1024*512)
-
-      self.working_dir = os.path.join(TEMP_DIR, 'emscripten_temp')
-      if not os.path.exists(self.working_dir): os.makedirs(self.working_dir)
-
-      assert not os.path.exists(JCache.get_cachename('emscript_files'))
-
-      srcs = {}
-      used_jcache = False
-
-      for args, input_file, expect_pre_save, expect_pre_load, expect_funcs_save, expect_funcs_load, expect_jsfuncs_save, expect_jsfuncs_load, expected in [
-        ([], 'hello_world_loop.cpp', False, False, False, False, False, False, []),
-        (['--jcache'], 'hello_world_loop.cpp', True, False, True, False, True, False, []),
-        (['--jcache'], 'hello_world_loop.cpp', False, True, False, True, False, True, []),
-        ([], 'hello_world_loop.cpp', False, False, False, False, False, False, []),
-        # new
-        ([], 'hello_world.cpp', False, False, False, False, False, False, []),
-        (['--jcache'], 'hello_world.cpp', True, False, True, False, True, False, []),
-        (['--jcache'], 'hello_world.cpp', False, True, False, True, False, True, []),
-        ([], 'hello_world.cpp', False, False, False, False, False, False, []),
-        # go back to old file, experience caching
-        (['--jcache'], 'hello_world_loop.cpp', False, True, False, True, False, True, []),
-        # new, large file
-        ([], 'hello_malloc.cpp', False, False, False, False, False, False, []),
-        (['--jcache'], 'hello_malloc.cpp', True, False, True, False, True, False, []),
-        (['--jcache'], 'hello_malloc.cpp', False, True, False, True, False, True, []),
-        ([], 'hello_malloc.cpp', False, False, False, False, False, False, []),
-        # new, huge file
-        ([], 'hello_libcxx.cpp', False, False, False, False, False, False, ('4 chunks',)),
-        (['--jcache'], 'hello_libcxx.cpp', True, False, True, False, True, False, []),
-        (['--jcache'], 'hello_libcxx.cpp', False, True, False, True, False, True, []),
-        ([], 'hello_libcxx.cpp', False, False, False, False, False, False, []),
-        # finally, build a file close to the previous, to see that some chunks are found in the cache and some not
-        (['--jcache'], 'hello_libcxx_mod1.cpp', False, True, True, True, True, True, []), # win on pre, mix on funcs, mix on jsfuncs
-        (['--jcache'], 'hello_libcxx_mod1.cpp', False, True, False, True, False, True, []),
-        (None, None, None, None, None, None, None, None, None), # clear
-        (['--jcache'], 'hello_libcxx_mod2.cpp', True, False, True, False, True, False, []), # load into cache
-        (['--jcache'], 'hello_libcxx_mod2a.cpp', False, True, True, True, True, True, []) # add a printf, do not lose everything
-      ]:
-        self.clear()
-        if args is None:
-          Cache.erase()
-          continue
-
-        print >> sys.stderr, args, input_file, expect_pre_save, expect_pre_load, expect_funcs_save, expect_funcs_load, expect_jsfuncs_save, expect_jsfuncs_load, expected
-
-        out, err = Popen([PYTHON, EMCC, '-O2', '-g', path_from_root('tests', input_file)] + args, stdout=PIPE, stderr=PIPE).communicate()
-        errtail = err.split('emcc invocation')[-1]
-        self.assertContained('hello, world!', run_js('a.out.js'), errtail)
-        assert (PRE_SAVE_MSG in err) == expect_pre_save, errtail
-        assert (PRE_LOAD_MSG in err) == expect_pre_load, errtail
-        assert (FUNC_CHUNKS_SAVE_MSG in err) == expect_funcs_save, errtail
-        assert (FUNC_CHUNKS_LOAD_MSG in err) == expect_funcs_load, errtail
-        assert (JSFUNC_CHUNKS_SAVE_MSG in err) == expect_jsfuncs_save, errtail
-        assert (JSFUNC_CHUNKS_LOAD_MSG in err) == expect_jsfuncs_load, errtail
-        for expect in expected: assert expect in err, expect + ' ? ' + errtail
-        curr = open('a.out.js').read()
-        if input_file not in srcs:
-          srcs[input_file] = curr
-        else:
-          #open('/home/alon/Dev/emscripten/a', 'w').write(srcs[input_file])
-          #open('/home/alon/Dev/emscripten/b', 'w').write(curr)
-          assert abs(len(curr)/float(len(srcs[input_file]))-1)<0.01, 'contents may shift in order, but must remain the same size  %d vs %d' % (len(curr), len(srcs[input_file])) + '\n' + errtail
-        used_jcache = used_jcache or ('--jcache' in args)
-        assert used_jcache == os.path.exists(JCache.get_cachename('emscript_files'))
-        #print >> sys.stderr, errtail
+      os.environ['EMCC_FAST_COMPILER'] = '0'
+
+      RELOOPER = Cache.get_path('relooper.js')
 
+      restore()
+      for phase in range(2): # 0: we wipe the relooper dir. 1: we have it, so should just update
+        if phase == 0: Cache.erase()
+        try_delete(RELOOPER)
+
+        for i in range(4):
+          print >> sys.stderr, phase, i
+          opt = min(i, 2)
+          try_delete('a.out.js')
+          output = Popen([PYTHON, EMCC, path_from_root('tests', 'hello_world_loop.cpp'), '-O' + str(opt), '-g'],
+                         stdout=PIPE, stderr=PIPE).communicate()
+          self.assertContained('hello, world!', run_js('a.out.js'))
+          output = '\n'.join(output)
+          assert ('bootstrapping relooper succeeded' in output) == (i == 1), 'only bootstrap on first O2: ' + output
+          assert os.path.exists(RELOOPER) == (i >= 1), 'have relooper on O2: ' + output
+          src = open('a.out.js').read()
+          main = src.split('function _main()')[1].split('\n}\n')[0]
+          assert ('while (1) {' in main or 'while(1){' in main or 'while(1) {' in main or '} while ($' in main or '}while($' in main) == (i >= 1), 'reloop code on O2: ' + main
+          assert ('switch' not in main) == (i >= 1), 'reloop code on O2: ' + main
     finally:
-      del os.environ['EMCC_DEBUG']
-      del os.environ['EMCC_JSOPT_MIN_CHUNK_SIZE']
+      del os.environ['EMCC_FAST_COMPILER']
 
   def test_nostdincxx(self):
     restore()
diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js
index fc195e03..240ee2bd 100644
--- a/tools/js-optimizer.js
+++ b/tools/js-optimizer.js
@@ -4525,10 +4525,10 @@ function outline(ast) {
     var size = measureSize(func);
     if (size <= extraInfo.sizeToOutline) {
       sizeToOutline = Infinity;
-      printErr('  no point in trying to reduce the size of ' + func[1] + ' which is ' + size + ' <= ' + extraInfo.sizeToOutline);
+      //printErr('  no point in trying to reduce the size of ' + func[1] + ' which is ' + size + ' <= ' + extraInfo.sizeToOutline);
     } else {
       sizeToOutline = Math.round(size/Math.max(2, asmData.intendedPieces--));
-      printErr('trying to reduce the size of ' + func[1] + ' which is ' + size + ' (>=? ' + extraInfo.sizeToOutline + '), aim for ' + sizeToOutline);
+      //printErr('trying to reduce the size of ' + func[1] + ' which is ' + size + ' (>=? ' + extraInfo.sizeToOutline + '), aim for ' + sizeToOutline);
     }
   }
 
@@ -4753,7 +4753,7 @@ function outline(ast) {
       }
     }
     outliningParents[newIdent] = func[1];
-    printErr('performed outline ' + [func[1], newIdent, 'pre size', originalCodeSize, 'resulting size', measureSize(code), 'overhead (w/r):', setSize(setSub(codeInfo.writes, owned)), setSize(setSub(codeInfo.reads, owned)), ' owned: ', setSize(owned), ' left: ', setSize(asmData.vars), setSize(asmData.params), ' loopsDepth: ', loops]);
+    //printErr('performed outline ' + [func[1], newIdent, 'pre size', originalCodeSize, 'resulting size', measureSize(code), 'overhead (w/r):', setSize(setSub(codeInfo.writes, owned)), setSize(setSub(codeInfo.reads, owned)), ' owned: ', setSize(owned), ' left: ', setSize(asmData.vars), setSize(asmData.params), ' loopsDepth: ', loops]);
     calculateThreshold(func, asmData);
     return [newFunc];
   }
@@ -4775,7 +4775,16 @@ function outline(ast) {
         for (var i = minIndex; i < stats.length; i++) {
           var stat = stats[i];
           if (stat[0] == 'stat') stat = stat[1];
-          if (stat[0] == 'assign' && stat[2][0] == 'name' && stat[2][1] == 'sp') minIndex = i+1; // cannot outline |sp = |
+          if (stat[0] == 'assign' && stat[2][0] == 'name' && stat[2][1] == 'sp') {
+            // cannot outline |sp = |
+            minIndex = i+1;
+            // When followed by a STACKTOP bump, preserve that too (we may need to replace it later)
+            stat = stats[i+1];
+            if (stat[0] == 'stat') stat = stat[1];
+            if (stat && stat[0] == 'assign' && stat[2][0] == 'name' && stat[2][1] == 'STACKTOP') {
+              minIndex = i+2;
+            }
+          }
         }
       }
     }
@@ -4899,7 +4908,7 @@ function outline(ast) {
 
   var maxTotalFunctions = Infinity; // debugging tool
 
-  printErr('\n');
+  //printErr('\n');
 
   var more = true;
   while (more) {
@@ -4926,7 +4935,27 @@ function outline(ast) {
           if ('sp' in asmData.vars) {
             // find stack bump (STACKTOP = STACKTOP + X | 0) and add the extra space
             var stackBumpNode = getStackBumpNode(stats);
-            if (stackBumpNode) stackBumpNode[3][2][3][1] = asmData.totalStackSize;
+            if (stackBumpNode) {
+              stackBumpNode[3][2][3][1] = asmData.totalStackSize;
+            } else {
+              // sp exists, but no stack bump, so we need to add it
+              var found = false;
+              for (var i = 0; i < stats.length; i++) {
+                var stat = stats[i];
+                if (stat[0] === 'stat') stat = stat[1];
+                if (stat[0] === 'assign' && stat[2][0] === 'name' && stat[2][1] === 'sp') {
+                  var newNode = ['stat', makeAssign(['name', 'STACKTOP'], ['binary', '|', ['binary', '+', ['name', 'STACKTOP'], ['num', asmData.totalStackSize]], ['num', 0]])];
+                  if (i+1 < stats.length) {
+                    stats.splice(i+1, 0, newNode);
+                  } else {
+                    stats.push(newNode);
+                  }
+                  found = true;
+                  break;
+                }
+              }
+              assert(found);
+            }
           } else if (!('sp' in asmData.params)) { // if sp is a param, then we are an outlined function, no need to add stack support for us
             // add sp variable and stack bump
             var index = getFirstIndexInNormalized(func, asmData);
@@ -4961,7 +4990,7 @@ function outline(ast) {
         }
         if (ret) {
           ret.push(func);
-          printErr('... resulting sizes of ' + func[1] + ' is ' + ret.map(measureSize) + '\n');
+          //printErr('... resulting sizes of ' + func[1] + ' is ' + ret.map(measureSize) + '\n');
         }
       }
       denormalizeAsm(func, asmData);
diff --git a/tools/nativize_llvm.py b/tools/nativize_llvm.py
index b327bdfc..52dfdea1 100755
--- a/tools/nativize_llvm.py
+++ b/tools/nativize_llvm.py
@@ -25,9 +25,11 @@ Popen([LLVM_OPT, filename, '-strip-debug', '-o', filename + '.clean.bc']).commun
 print 'bc => s'
 for params in [['-march=x86'], ['-march=x86-64']]: # try x86, then x86-64 FIXME
   print 'params', params
-  Popen([LLVM_COMPILER] + params + [filename + '.clean.bc', '-o', filename + '.s']).communicate()[0]
-  print 's => o'
-  Popen(['as', filename + '.s', '-o', filename + '.o']).communicate()[0]
+  for triple in [['-mtriple=i386-pc-linux-gnu'], []]:
+    Popen([LLVM_COMPILER] + params + triple + [filename + '.clean.bc', '-o', filename + '.s']).communicate()[0]
+    print 's => o'
+    Popen(['as', filename + '.s', '-o', filename + '.o']).communicate()[0]
+    if os.path.exists(filename + '.o'): break
   if os.path.exists(filename + '.o'): break
 print 'o => runnable'
 Popen(['g++', path_from_root('system', 'lib', 'debugging.cpp'), filename + '.o', '-o', filename + '.run'] + ['-l' + lib for lib in libs]).communicate()[0]
diff --git a/tools/shared.py b/tools/shared.py
index c4b01518..7a49f158 100644
--- a/tools/shared.py
+++ b/tools/shared.py
@@ -270,7 +270,7 @@ if EM_POPEN_WORKAROUND and os.name == 'nt':
 
 # Expectations
 
-EXPECTED_LLVM_VERSION = (3,2)
+EXPECTED_LLVM_VERSION = (3,3)
 
 actual_clang_version = None
 
@@ -303,6 +303,7 @@ def check_fastcomp():
       print >> sys.stderr, '==========================================================================='
       print >> sys.stderr, llc_version_info,
       print >> sys.stderr, '==========================================================================='
+      logging.critical('you can fall back to the older (pre-fastcomp) compiler core, although that is not recommended, see https://github.com/kripken/emscripten/wiki/LLVM-Backend')
       return False
     return True
   except Exception, e:
@@ -379,7 +380,7 @@ def check_sanity(force=False):
     # some warning, mostly not fatal checks - do them even if EM_IGNORE_SANITY is on
     check_llvm_version()
     check_node_version()
-    if os.environ.get('EMCC_FAST_COMPILER') == '1':
+    if os.environ.get('EMCC_FAST_COMPILER') != '0':
       fastcomp_ok = check_fastcomp()
 
     if os.environ.get('EM_IGNORE_SANITY'):
@@ -402,7 +403,7 @@ def check_sanity(force=False):
         logging.critical('Cannot find %s, check the paths in %s' % (cmd, EM_CONFIG))
         sys.exit(1)
 
-    if os.environ.get('EMCC_FAST_COMPILER') == '1':
+    if os.environ.get('EMCC_FAST_COMPILER') != '0':
       if not fastcomp_ok:
         logging.critical('failing sanity checks due to previous fastcomp failure')
         sys.exit(1)
@@ -803,6 +804,8 @@ class Settings2(type):
 
     @classmethod
     def apply_opt_level(self, opt_level, noisy=False):
+      if opt_level == 0 and os.environ.get('EMCC_FAST_COMPILER') == '0':
+        self.attrs['ASM_JS'] = 0 # non-fastcomp has asm off in -O1
       if opt_level >= 1:
         self.attrs['ASM_JS'] = 1
         self.attrs['ASSERTIONS'] = 0
@@ -1467,7 +1470,7 @@ class Building:
   @staticmethod
   def ensure_relooper(relooper):
     if os.path.exists(relooper): return
-    if os.environ.get('EMCC_FAST_COMPILER') == '1':
+    if os.environ.get('EMCC_FAST_COMPILER') != '0':
       logging.debug('not building relooper to js, using it in c++ backend')
       return
 
@@ -1542,7 +1545,7 @@ class Building:
       text = m.groups(0)[0]
       assert text.count('(') == 1 and text.count(')') == 1, 'must have simple expressions in emscripten_jcache_printf calls, no parens'
       assert text.count('"') == 2, 'must have simple expressions in emscripten_jcache_printf calls, no strings as varargs parameters'
-      if os.environ.get('EMCC_FAST_COMPILER') == '1': # fake it in fastcomp
+      if os.environ.get('EMCC_FAST_COMPILER') != '0': # fake it in fastcomp
         return text.replace('emscripten_jcache_printf', 'printf')
       start = text.index('(')
       end = text.rindex(')')
diff --git a/tools/test-js-optimizer-asm-outline1-output.js b/tools/test-js-optimizer-asm-outline1-output.js
index 27f93d8a..c4792c51 100644
--- a/tools/test-js-optimizer-asm-outline1-output.js
+++ b/tools/test-js-optimizer-asm-outline1-output.js
@@ -423,6 +423,32 @@ function switchh2() {
  }
  STACKTOP = sp;
 }
+function stackSet(x1, x2, x3, x4, x5) {
+ x1 = x1 | 0;
+ x2 = x2 | 0;
+ x3 = x3 | 0;
+ x4 = x4 | 0;
+ x5 = x5 | 0;
+ var sp = 0;
+ sp = STACKTOP;
+ STACKTOP = STACKTOP + 282 | 0;
+ c(1);
+ c(2);
+ c(3);
+ c(4);
+ c(5);
+ c(6);
+ c(7);
+ c(8);
+ c(9);
+ c(10);
+ HEAP32[sp + 66 >> 2] = 0;
+ HEAP32[sp + 70 >> 2] = 0;
+ stackSet$1(sp);
+ HEAP32[sp + 58 >> 2] = 0;
+ HEAP32[sp + 62 >> 2] = 0;
+ stackSet$0(sp);
+}
 function lin$0(sp) {
  sp = sp | 0;
  c(14);
@@ -926,4 +952,26 @@ function switchh2$2(sp) {
  } while (0);
  HEAP32[sp + 8 >> 2] = helper$0;
 }
+function stackSet$0(sp) {
+ sp = sp | 0;
+ c(7);
+ c(8);
+ c(9);
+ c(10);
+ c(11);
+ c(12);
+ c(13);
+}
+function stackSet$1(sp) {
+ sp = sp | 0;
+ c(11);
+ c(12);
+ c(13);
+ c(1);
+ c(2);
+ c(3);
+ c(4);
+ c(5);
+ c(6);
+}
 
diff --git a/tools/test-js-optimizer-asm-outline1.js b/tools/test-js-optimizer-asm-outline1.js
index b7ec9011..f640d11d 100644
--- a/tools/test-js-optimizer-asm-outline1.js
+++ b/tools/test-js-optimizer-asm-outline1.js
@@ -347,5 +347,42 @@ function switchh2() {
       print(9);
   }
 }
+function stackSet(x1, x2, x3, x4, x5) {
+ x1 = x1 | 0;
+ x2 = x2 | 0;
+ x3 = x3 | 0;
+ x4 = x4 | 0;
+ x5 = x5 | 0;
+ var sp = 0, a = 0, b = 0, cc = 0, d = 0, e = 0, f = 0, g = 0;
+ var sp1 = 0, a1 = 0, b1 = 0, c1 = 0, d1 = 0, e1 = 0, f1 = 0, g1 = 0;
+ sp = STACKTOP;
+ STACKTOP = STACKTOP + 10 | 0;
+ c(1);
+ c(2);
+ c(3);
+ c(4);
+ c(5);
+ c(6);
+ c(7);
+ c(8);
+ c(9);
+ c(10);
+ c(11);
+ c(12);
+ c(13);
+ c(1);
+ c(2);
+ c(3);
+ c(4);
+ c(5);
+ c(6);
+ c(7);
+ c(8);
+ c(9);
+ c(10);
+ c(11);
+ c(12);
+ c(13);
+}
 // EMSCRIPTEN_GENERATED_FUNCTIONS
 // EXTRA_INFO: { "sizeToOutline": 30, "allowCostlyOutlines": 1 }
diff --git a/tools/test-js-optimizer-asm-outline2-output.js b/tools/test-js-optimizer-asm-outline2-output.js
index 2658fda0..923cd7df 100644
--- a/tools/test-js-optimizer-asm-outline2-output.js
+++ b/tools/test-js-optimizer-asm-outline2-output.js
@@ -25,6 +25,7 @@ function _free($mem) {
  $mem = $mem | 0;
  var $5 = 0, $10 = 0, $16 = 0, $21 = 0, $25 = 0, $26 = 0, $psize_0 = 0, $p_0 = 0, $189 = 0, $194 = 0, sp = 0, helper$0 = 0;
  sp = STACKTOP;
+ STACKTOP = STACKTOP + 864 | 0;
  if (($mem | 0) == 0) {
   STACKTOP = sp;
   return;