RETAIN_COMPILER_SETTINGS, Runtime.getCompilerSetting and emscripten_get_compiler_setting - an optional way to look up compiler flags at runtime

9 files changed, 95 insertions, 3 deletions

diff --git a/emcc b/emcc
index 7aaf681b..22bf89c8 100755
--- a/emcc
+++ b/emcc
@@ -1308,6 +1308,10 @@ try:
   if js_opts:
     shared.Settings.RUNNING_JS_OPTS = 1
 
+  shared.Settings.EMSCRIPTEN_VERSION = shared.EMSCRIPTEN_VERSION
+  shared.Settings.OPT_LEVEL = opt_level
+  shared.Settings.DEBUG_LEVEL = debug_level
+
   ## Compile source code to bitcode
 
   logging.debug('compiling to bitcode')
diff --git a/src/library.js b/src/library.js
index f69b52e5..1b5e8b20 100644
--- a/src/library.js
+++ b/src/library.js
@@ -9051,6 +9051,20 @@ LibraryManager.library = {
     _emscripten_log_js(flags, str);
   },
 
+  emscripten_get_compiler_setting: function(name) {
+    name = Pointer_stringify(name);
+
+    var ret = Runtime.getCompilerSetting(name);
+    if (typeof ret === 'number') return ret;
+
+    if (!_emscripten_get_compiler_setting.cache) _emscripten_get_compiler_setting.cache = {};
+    var cache = _emscripten_get_compiler_setting.cache;
+    var fullname = name + '__str';
+    var fullret = cache[fullname];
+    if (fullret) return fullret;
+    return cache[fullname] = allocate(intArrayFromString(ret + ''), 'i8', ALLOC_NORMAL);
+  },
+
   //============================
   // emscripten vector ops
   //============================
diff --git a/src/runtime.js b/src/runtime.js
index a9265e70..0c724e50 100644
--- a/src/runtime.js
+++ b/src/runtime.js
@@ -487,6 +487,19 @@ var Runtime = {
     }
   },
 
+#if RETAIN_COMPILER_SETTINGS
+  compilerSettings: {},
+#endif
+
+  getCompilerSetting: function(name) {
+#if RETAIN_COMPILER_SETTINGS == 0
+    throw 'You must build with -s RETAIN_COMPILER_SETTINGS=1 for Runtime.getCompilerSetting or emscripten_get_compiler_setting to work';
+#else
+    if (!(name in Runtime.compilerSettings)) return 'invalid compiler setting: ' + name;
+    return Runtime.compilerSettings[name];
+#endif
+  },
+
 #if RUNTIME_DEBUG
   debug: true, // Switch to false at runtime to disable logging at the right times
 
@@ -612,3 +625,12 @@ function reSign(value, bits, ignore) {
 // Then 'dynamic' memory for sbrk.
 Runtime.GLOBAL_BASE = Runtime.alignMemory(1);
 
+if (RETAIN_COMPILER_SETTINGS) {
+  var blacklist = set('RELOOPER', 'STRUCT_INFO');
+  for (var x in this) {
+    try {
+      if (x[0] !== '_' && !(x in blacklist) && x == x.toUpperCase() && (typeof this[x] === 'number' || typeof this[x] === 'string' || this.isArray())) Runtime.compilerSettings[x] = this[x];
+    } catch(e){}
+  }
+}
+
diff --git a/src/settings.js b/src/settings.js
index 1db91dca..c8114059 100644
--- a/src/settings.js
+++ b/src/settings.js
@@ -315,6 +315,17 @@ var EXPORT_ALL = 0; // If true, we export all the symbols. Note that this does *
                     // still eliminate functions as dead. This just exports them on the Module object.
 var EXPORT_BINDINGS = 0; // Export all bindings generator functions (prefixed with emscripten_bind_). This
                          // is necessary to use the bindings generator with asm.js
+var RETAIN_COMPILER_SETTINGS = 0; // Remembers the values of these settings, and makes them accessible
+                                  // through Runtime.getCompilerSetting and emscripten_get_compiler_setting.
+                                  // To see what is retained, look for compilerSettings in the generated code.
+
+
+var EMSCRIPTEN_VERSION = ''; // this will contain the emscripten version. you should not modify it. This
+                             // and the following few settings are useful in combination with
+                             // RETAIN_COMPILER_SETTINGS
+var OPT_LEVEL = 0;           // this will contain the optimization level (-Ox). you should not modify it.
+var DEBUG_LEVEL = 0;         // this will contain the debug level (-gx). you should not modify it.
+
 
 // JS library functions (C functions implemented in JS)
 // that we include by default. If you want to make sure
diff --git a/src/utility.js b/src/utility.js
index 178c596b..54cc2d69 100644
--- a/src/utility.js
+++ b/src/utility.js
@@ -200,11 +200,11 @@ function dprint() {
   printErr(text);
 }
 
-var PROF_ORIGIN = Date.now();
-var PROF_TIME = PROF_ORIGIN;
+var _PROF_ORIGIN = Date.now();
+var _PROF_TIME = _PROF_ORIGIN;
 function PROF(pass) {
   if (!pass) {
-    dprint("Profiling: " + ((Date.now() - PROF_TIME)/1000) + ' seconds, total: ' + ((Date.now() - PROF_ORIGIN)/1000));
+    dprint("Profiling: " + ((Date.now() - _PROF_TIME)/1000) + ' seconds, total: ' + ((Date.now() - _PROF_ORIGIN)/1000));
   }
   PROF_TIME = Date.now();
 }
diff --git a/system/include/emscripten/emscripten.h b/system/include/emscripten/emscripten.h
index eb5ded91..426206c4 100644
--- a/system/include/emscripten/emscripten.h
+++ b/system/include/emscripten/emscripten.h
@@ -420,6 +420,27 @@ int emscripten_get_worker_queue_size(worker_handle worker);
 #define EMSCRIPTEN_NETWORK_WEBRTC     1
 void emscripten_set_network_backend(int backend);
 
+/*
+ * Returns the value of a compiler setting. For example
+ *
+ *   emscripten_get_compiler_setting("PRECISE_F32")
+ *
+ * will return an integer representing the value of
+ * PRECISE_F32 during compilation. For values containing
+ * anything other than an integer, a string is returned
+ * (you will need to cast the int return value to a char*).
+ *
+ * Some useful things this can do is provide the
+ * version of emscripten ("EMSCRIPTEN_VERSION"), the optimization
+ * level ("OPT_LEVEL"), debug level ("DEBUG_LEVEL"), etc.
+ *
+ * For this command to work, you must build with
+ *   -s RETAIN_COMPILER_SETTINGS=1
+ * as otherwise we do not want to increase the build size
+ * with this metadata.
+ */
+int emscripten_get_compiler_setting(const char *name);
+
 /* Internal APIs. Be careful with these. */
 
 /*
diff --git a/tests/core/emscripten_get_compiler_setting.c b/tests/core/emscripten_get_compiler_setting.c
new file mode 100644
index 00000000..41eb8e38
--- /dev/null
+++ b/tests/core/emscripten_get_compiler_setting.c
@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <assert.h>
+#include <emscripten.h>
+
+int main() {
+  printf("QS: %d\n", emscripten_get_compiler_setting("QUANTUM_SIZE"));
+  assert((unsigned)emscripten_get_compiler_setting("OPT_LEVEL") <= 3);
+  assert((unsigned)emscripten_get_compiler_setting("DEBUG_LEVEL") <= 4);
+  printf("EV: %s\n", (char*)emscripten_get_compiler_setting("EMSCRIPTEN_VERSION"));
+}
+
diff --git a/tests/core/emscripten_get_compiler_setting.out b/tests/core/emscripten_get_compiler_setting.out
new file mode 100644
index 00000000..cd520064
--- /dev/null
+++ b/tests/core/emscripten_get_compiler_setting.out
@@ -0,0 +1,2 @@
+QS: 4
+EV: waka
diff --git a/tests/test_core.py b/tests/test_core.py
index 6a9ef979..045b43c1 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -1925,6 +1925,13 @@ def process(filename):
         self.emcc_args += ['--closure', '1'] # Use closure here for some additional coverage
       self.do_run(open(path_from_root('tests', 'emscripten_get_now.cpp')).read(), 'Timer resolution is good.')
 
+  def test_emscripten_get_compiler_setting(self):
+    test_path = path_from_root('tests', 'core', 'emscripten_get_compiler_setting')
+    src, output = (test_path + s for s in ('.c', '.out'))
+    self.do_run(open(src).read(), 'You must build with -s RETAIN_COMPILER_SETTINGS=1')
+    Settings.RETAIN_COMPILER_SETTINGS = 1
+    self.do_run(open(src).read(), open(output).read().replace('waka', EMSCRIPTEN_VERSION))
+
   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')