refactor memory allocation in places that might happen before malloc is ready

Author: kripken

src/jsifier.js

@@ -271,7 +271,7 @@ function JSify(data, functionsOnly) {
           print('STATIC_BASE = ' + Runtime.GLOBAL_BASE + ';\n');
           print('STATICTOP = STATIC_BASE + ' + Runtime.alignMemory(Variables.nextIndexedOffset) + ';\n');
         } else {
-          print('gb = parentModule["_malloc"]({{{ STATIC_BUMP }}});\n');
+          print('gb = getMemory({{{ STATIC_BUMP }}});\n');
           print('// STATICTOP = STATIC_BASE + ' + Runtime.alignMemory(Variables.nextIndexedOffset) + ';\n'); // comment as metadata only
         }
       }

src/preamble.js

@@ -433,6 +433,13 @@ function allocate(slab, types, allocator, ptr) {
 }
 Module['allocate'] = allocate;
 
+// Allocate memory during any stage of startup - static memory early on, dynamic memory later, malloc when ready
+function getMemory(size) {
+  if (!staticSealed) return Runtime.staticAlloc(size);
+  if (typeof _sbrk !== 'undefined' && !_sbrk.called) return Runtime.dynamicAlloc(size);
+  return _malloc(size);
+}
+
 function Pointer_stringify(ptr, /* optional */ length) {
   if (length === 0 || !ptr) return '';
   // TODO: use TextDecoder

src/shell_sharedlib.js

@@ -10,7 +10,7 @@
 
   var gb = 0;
   // Each module has its own stack
-  var STACKTOP = parentModule['_malloc'](TOTAL_STACK);
+  var STACKTOP = getMemory(TOTAL_STACK);
   assert(STACKTOP % 8 == 0);
   var STACK_MAX = STACKTOP + TOTAL_STACK;
   Module.cleanups.push(function() {

tools/emterpretify.py

@@ -1025,13 +1025,13 @@ def post_process_code(code):
 
   # set up emterpreter stack top (note we must use malloc if in a shared lib, or other enviroment where static memory is sealed)
   js = ['''
-var EMTSTACKTOP = (staticSealed ? _malloc : Runtime.staticAlloc)(%s);
+var EMTSTACKTOP = getMemory(%s);
 var EMT_STACK_MAX = EMTSTACKTOP + %d;
 ''' % (EMT_STACK_MAX, EMT_STACK_MAX)]
 
   # write out our bytecode, and runtime relocation logic
   js += ['''
-var eb = (staticSealed ? _malloc : Runtime.staticAlloc)(%s);
+var eb = getMemory(%s);
 assert(eb %% 8 === 0);
 __ATPRERUN__.push(function() {
 ''' % len(all_code)]