make EM_ASM use strings on the heap, so it works in asm, and cache the generated functions

3 files changed, 31 insertions, 13 deletions

diff --git a/src/library.js b/src/library.js
index 48f613e0..5e71b087 100644
--- a/src/library.js
+++ b/src/library.js
@@ -8613,6 +8613,15 @@ LibraryManager.library = {
     Runtime.stackAlloc(-4*i); // free up the stack space we know is ok to free
   },
 
+  emscripten_asm_const: function(code) {
+    // code is a constant string on the heap, so we can cache these
+    if (!Runtime.asmConstCache) Runtime.asmConstCache = {};
+    var func = Runtime.asmConstCache[code];
+    if (func) return func();
+    func = Runtime.asmConstCache[code] = eval('(function(){ ' + Pointer_stringify(code) + ' })'); // new Function does not allow upvars in node
+    return func();
+  },
+
   //============================
   // i64 math
   //============================
diff --git a/system/include/emscripten/emscripten.h b/system/include/emscripten/emscripten.h
index 430fbc1c..d30620ec 100644
--- a/system/include/emscripten/emscripten.h
+++ b/system/include/emscripten/emscripten.h
@@ -23,10 +23,13 @@ extern "C" {
  *
  *    EM_ASM(window.alert('hai'));
  *
+ * This also works with asm.js, as it outlines the code (it
+ * does a function call to reach it).
+ *
  * Note: double-quotes (") are not supported, but you can use
  *       single-quotes (') in js anyhow.
  */
-#define EM_ASM(...) asm(#__VA_ARGS__)
+#define EM_ASM(...) emscripten_asm_const(#__VA_ARGS__)
 
 /*
  * Forces LLVM to not dead-code-eliminate a function. Note that
@@ -376,6 +379,8 @@ int emscripten_get_worker_queue_size(worker_handle worker);
 #define EMSCRIPTEN_NETWORK_WEBRTC     1
 void emscripten_set_network_backend(int backend);
 
+/* Internal APIs. Be careful with these. */
+
 /*
  * Profiling tools.
  * INIT must be called first, with the maximum identifier that
@@ -413,6 +418,9 @@ void emscripten_jcache_printf(const char *format, ...);
 void emscripten_jcache_printf_(...); /* internal use */
 #endif
 
+/* Helper API for EM_ASM - do not call this yourself */
+void emscripten_asm_const(const char *code);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/tests/test_core.py b/tests/test_core.py
index 80933937..b4668584 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -3841,25 +3841,26 @@ def process(filename):
       self.do_run(src, '4\n200\ndone\n')
 
   def test_inlinejs3(self):
-      if Settings.ASM_JS: return self.skip('asm does not support random code, TODO: something that works in asm')
-      src = r'''
-        #include <stdio.h>
-        #include <emscripten.h>
+    src = r'''
+      #include <stdio.h>
+      #include <emscripten.h>
 
-        int main() {
-          EM_ASM(Module.print('hello dere1'));
-          EM_ASM(
-            Module.print('hello dere2');
-          );
+      int main() {
+        EM_ASM(Module.print('hello dere1'));
+        EM_ASM(
+          Module.print('hello dere2');
+        );
+        for (int i = 0; i < 3; i++) {
           EM_ASM(
             Module.print('hello dere3');
             Module.print('hello dere' + 4);
           );
-          return 0;
         }
-        '''
+        return 0;
+      }
+      '''
 
-      self.do_run(src, 'hello dere1\nhello dere2\nhello dere3\nhello dere4\n')
+    self.do_run(src, 'hello dere1\nhello dere2\nhello dere3\nhello dere4\nhello dere3\nhello dere4\nhello dere3\nhello dere4\n')
 
   def test_memorygrowth(self):
     if Settings.USE_TYPED_ARRAYS == 0: return self.skip('memory growth is only supported with typed arrays')