preprocessor + example use in SAFE_HEAP

3 files changed, 68 insertions, 7 deletions

diff --git a/src/parser.js b/src/parser.js
index b9873175..19e073bc 100644
--- a/src/parser.js
+++ b/src/parser.js
@@ -6,10 +6,6 @@
  *    * Re-use variables (of the same kind, native/nativized vs. emulated).
  */
 
-// Options
-
-LINEDEBUG = 0;
-
 // Prep - allow this to run in both SpiderMonkey and V8
 
 if (!this['load']) {
@@ -26,6 +22,34 @@ load('snippets.js');
 
 // Tools
 
+// Simple #if/else/endif preprocessing for a file. Checks if the
+// ident checked is true in our global.
+function preprocess(text) {
+  var lines = text.split('\n');
+  var ret = '';
+  var show = true;
+  for (var i = 0; i < lines.length; i++) {
+    var line = lines[i];
+    if (line[0] != '#') {
+      if (show) {
+        ret += line + '\n';
+      }
+    } else {
+      if (line[1] == 'i') { // if
+        var ident = line.substr(4);
+        show = !!this[ident];
+      } else if (line[2] == 'l') { // else
+        show = !show;
+      } else if (line[2] == 'n') { // endif
+        show = true;
+      } else {
+        throw "Unclear preprocessor command: " + line;
+      }
+    }
+  }
+  return ret;
+}
+
 function addPointing(type) { return type + '*' }
 function removePointing(type, num) {
   if (num === 0) return type;
@@ -1829,7 +1853,11 @@ function JSify(data) {
   }
 
   function makeSetValue(ptr, pos, value, noNeedFirst) {
-    return makeGetSlab(ptr) + '[' + (noNeedFirst ? '0' : makeGetPos(ptr)) + (pos ? ' + ' + pos : '') + '] = ' + value;
+    if (SAFE_HEAP) {
+      return 'SAFE_HEAP_STORE(' + (noNeedFirst ? '0' : makeGetPos(ptr)) + (pos ? ' + ' + pos : '') + ', ' + value + ')';
+    } else {
+      return makeGetSlab(ptr) + '[' + (noNeedFirst ? '0' : makeGetPos(ptr)) + (pos ? ' + ' + pos : '') + '] = ' + value;
+    }
   }
 
   function makeEmptyStruct(type) {
@@ -2390,7 +2418,11 @@ function JSify(data) {
 
     // Special cases
     if (ident == '_llvm_va_start') {
-      return 'HEAP[' + params[0].ident + '] = Pointer_make(Array.prototype.slice.call(arguments, 1).concat([0]), 0)'; // XXX 1
+      if (SAFE_HEAP) {
+        return 'SAFE_HEAP_STORE(' + params[0].ident + ', Pointer_make(Array.prototype.slice.call(arguments, 1).concat([0]), 0))';
+      } else {
+        return 'HEAP[' + params[0].ident + '] = Pointer_make(Array.prototype.slice.call(arguments, 1).concat([0]), 0)'; // XXX 1
+      }
     } else if (ident == '_llvm_va_end') {
       return ';'
     }
@@ -2438,7 +2470,7 @@ function JSify(data) {
     return ret.map(function(item) { return item.JS }).join('\n');
   }
 
-  return read('preamble.js') + finalCombiner(substrate.solve()) + read('postamble.js');
+  return preprocess(read('preamble.js')) + finalCombiner(substrate.solve()) + read('postamble.js');
 //  return finalCombiner(substrate.solve());
 }
 
diff --git a/src/preamble.js b/src/preamble.js
index 0e21f70e..59c3e842 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -11,6 +11,25 @@ var __ATEXIT__ = [];
 var HEAP = [];
 var HEAPTOP = 0;
 
+#if SAFE_HEAP
+// Semi-manual memory corruption debugging
+HEAP_WATCHED = {};
+function SAFE_HEAP_STORE(dest, value) {
+  if (dest in HEAP_WATCHED) {
+    print((new Error()).stack);
+    throw "Bad store!" + dest;
+  }
+  HEAP[dest] = value;
+}
+function __Z16PROTECT_HEAPADDRPv(dest) {
+  HEAP_WATCHED[dest] = true;
+}
+function __Z18UNPROTECT_HEAPADDRPv(dest) {
+  delete HEAP_WATCHED[dest];
+}
+//==========================================
+#endif
+
 function abort(text) {
   text = "ABORT: " + text;
   print(text + "\n");
@@ -41,7 +60,11 @@ function Pointer_make(slab, pos) {
   // Finalize
   var ret = _malloc(Math.max(slab.length - pos, 1));
   for (var i = 0; i < slab.length - pos; i++) {
+#if SAFE_HEAP
+    SAFE_HEAP_STORE(ret + i, slab[pos + i]);
+#else
     HEAP[ret + i] = slab[pos + i];
+#endif
   }
   return ret;
 //  return { slab: slab, pos: pos ? pos : 0 };
@@ -157,7 +180,11 @@ function _atoi(s) {
 function _llvm_memcpy_i32(dest, src, num, idunno) {
 // XXX hardcoded ptr impl
   for (var i = 0; i < num; i++) {
+#if SAFE_HEAP
+    SAFE_HEAP_STORE(dest + i, HEAP[src + i]);
+#else
     HEAP[dest + i] = HEAP[src + i];
+#endif
   }
 //  dest = Pointer_niceify(dest);
 //  src = Pointer_niceify(src);
diff --git a/src/settings.js b/src/settings.js
index 287caf8f..65cb8f70 100644
--- a/src/settings.js
+++ b/src/settings.js
@@ -1,3 +1,5 @@
 OPTIMIZE = 1;
 RELOOP = 1;
+LINEDEBUG = 0;
+SAFE_HEAP = 0;