enable a form of safe heap in asm, using js optimizer pass to ensure full coverage and support for fastcomp

emcc

@@ -1196,7 +1196,6 @@ try:
     shared.Settings.ASM_JS = 1
     assert shared.Settings.ALLOW_MEMORY_GROWTH == 0, 'memory growth not supported in fastcomp yet'
     assert shared.Settings.UNALIGNED_MEMORY == 0, 'forced unaligned memory not supported in fastcomp'
-    assert shared.Settings.SAFE_HEAP == 0, 'safe heap not supported in fastcomp yet'
     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.RESERVED_FUNCTION_POINTERS == 0, 'reserved function pointers not supported in fastcomp'
@@ -1230,6 +1229,9 @@ try:
       shared.Settings.CORRECT_OVERFLOWS = 1
     assert not shared.Settings.PGO, 'cannot run PGO in ASM_JS mode'
 
+    if shared.Settings.SAFE_HEAP and not js_opts:
+      logging.warning('asm.js+SAFE_HEAP requires js opts to be run (-O1 or above by default)')
+
   if shared.Settings.CORRECT_SIGNS >= 2 or shared.Settings.CORRECT_OVERFLOWS >= 2 or shared.Settings.CORRECT_ROUNDINGS >= 2:
     debug_level = 4 # must keep debug info to do line-by-line operations
 
@@ -1991,6 +1993,8 @@ try:
     if DEBUG: save_intermediate('closure')
 
   if js_opts:
+    if shared.Settings.ASM_JS and shared.Settings.SAFE_HEAP: js_optimizer_queue += ['safeHeap']
+
     if shared.Settings.OUTLINING_LIMIT > 0 and shared.Settings.ASM_JS:
       js_optimizer_queue += ['outline']
       js_optimizer_extra_info['sizeToOutline'] = shared.Settings.OUTLINING_LIMIT

emscripten.py

@@ -455,7 +455,7 @@ def emscript(infile, settings, outfile, libraries=[], compiler_engine=None,
 
     basic_funcs = ['abort', 'assert', 'asmPrintInt', 'asmPrintFloat'] + [m.replace('.', '_') for m in math_envs]
     if settings['RESERVED_FUNCTION_POINTERS'] > 0: basic_funcs.append('jsCall')
-    if settings['SAFE_HEAP']: basic_funcs += ['SAFE_HEAP_LOAD', 'SAFE_HEAP_STORE', 'SAFE_HEAP_CLEAR']
+    if settings['SAFE_HEAP']: basic_funcs += ['SAFE_HEAP_LOAD', 'SAFE_HEAP_STORE']
     if settings['CHECK_HEAP_ALIGN']: basic_funcs += ['CHECK_ALIGN_2', 'CHECK_ALIGN_4', 'CHECK_ALIGN_8']
     if settings['ASSERTIONS']:
       basic_funcs += ['nullFunc']
@@ -956,7 +956,7 @@ def emscript_fast(infile, settings, outfile, libraries=[], compiler_engine=None,
 
     basic_funcs = ['abort', 'assert', 'asmPrintInt', 'asmPrintFloat'] + [m.replace('.', '_') for m in math_envs]
     if settings['RESERVED_FUNCTION_POINTERS'] > 0: basic_funcs.append('jsCall')
-    if settings['SAFE_HEAP']: basic_funcs += ['SAFE_HEAP_LOAD', 'SAFE_HEAP_STORE', 'SAFE_HEAP_CLEAR']
+    if settings['SAFE_HEAP']: basic_funcs += ['SAFE_HEAP_LOAD', 'SAFE_HEAP_STORE']
     if settings['CHECK_HEAP_ALIGN']: basic_funcs += ['CHECK_ALIGN_2', 'CHECK_ALIGN_4', 'CHECK_ALIGN_8']
     if settings['ASSERTIONS']:
       basic_funcs += ['nullFunc']

src/parseTools.js

@@ -1327,8 +1327,13 @@ function makeGetValue(ptr, pos, type, noNeedFirst, unsigned, ignore, align, noSa
     var printType = type;
     if (printType !== 'null' && printType[0] !== '#') printType = '"' + safeQuote(printType) + '"';
     if (printType[0] === '#') printType = printType.substr(1);
-    return asmCoercion('SAFE_HEAP_LOAD(' + asmCoercion(offset, 'i32') + ', ' + (ASM_JS ? 0 : printType) + ', ' + (!!unsigned+0) + ', ' + ((!checkSafeHeap() || ignore)|0) + ')', type);
+    if (ASM_JS) {
+      if (!ignore) return asmCoercion('SAFE_HEAP_LOAD(' + asmCoercion(offset, 'i32') + ', ' + Runtime.getNativeTypeSize(type) + ', ' + ((type in Runtime.FLOAT_TYPES)|0) + ')', type);
+      // else fall through
     } else {
+      return asmCoercion('SAFE_HEAP_LOAD(' + offset + ', ' + (ASM_JS ? 0 : printType) + ', ' + (!!unsigned+0) + ', ' + ((!checkSafeHeap() || ignore)|0) + ')', type);
+    }
+  }
   var ret = makeGetSlabs(ptr, type, false, unsigned)[0] + '[' + getHeapOffset(offset, type, forceAsm) + ']';
   if (ASM_JS && (phase == 'funcs' || forceAsm)) {
     ret = asmCoercion(ret, type);
@@ -1338,7 +1343,6 @@ function makeGetValue(ptr, pos, type, noNeedFirst, unsigned, ignore, align, noSa
                                 'temp' + (type in Runtime.FLOAT_TYPES ? 'Double' : 'Int'));
   }
   return ret;
-  }
 }
 
 function makeGetValueAsm(ptr, pos, type, unsigned) {
@@ -1435,10 +1439,14 @@ function makeSetValue(ptr, pos, value, type, noNeedFirst, ignore, align, noSafe,
     var printType = type;
     if (printType !== 'null' && printType[0] !== '#') printType = '"' + safeQuote(printType) + '"';
     if (printType[0] === '#') printType = printType.substr(1);
-    return 'SAFE_HEAP_STORE(' + asmCoercion(offset, 'i32') + ', ' + asmCoercion(value, type) + ', ' + (ASM_JS ? 0 : printType) + ', ' + ((!checkSafeHeap() || ignore)|0) + ')';
+    if (ASM_JS) {
+      if (!ignore) return asmCoercion('SAFE_HEAP_STORE(' + asmCoercion(offset, 'i32') + ', ' + asmCoercion(value, type) + ', ' + Runtime.getNativeTypeSize(type) + ', ' + ((type in Runtime.FLOAT_TYPES)|0) + ')', type);
+      // else fall through
     } else {
-    return makeGetSlabs(ptr, type, true).map(function(slab) { return slab + '[' + getHeapOffset(offset, type, forceAsm) + ']=' + value }).join(sep);
+      return 'SAFE_HEAP_STORE(' + offset + ', ' + value + ', ' + (ASM_JS ? 0 : printType) + ', ' + ((!checkSafeHeap() || ignore)|0) + ')';
     }
+  }
+  return makeGetSlabs(ptr, type, true).map(function(slab) { return slab + '[' + getHeapOffset(offset, type, forceAsm) + ']=' + value }).join(sep);
 }
 
 function makeSetValueAsm(ptr, pos, value, type, noNeedFirst, ignore, align, noSafe, sep, forcedAlign) {

src/preamble.js

@@ -21,6 +21,7 @@ Module.print = Module.printErr = function(){};
 #endif
 
 #if SAFE_HEAP
+#if ASM_JS == 0
 //========================================
 // Debugging tools - Heap
 //========================================
@@ -166,6 +167,38 @@ function SAFE_HEAP_FILL_HISTORY(from, to, type) {
 }
 
 //==========================================
+#else
+// ASM_JS safe heap
+
+function getSafeHeapType(bytes, isFloat) {
+  switch (bytes) {
+    case 1: return 'i8';
+    case 2: return 'i16';
+    case 4: return isFloat ? 'float' : 'i32';
+    case 8: return 'double';
+    default: assert(0);
+  }
+}
+
+function SAFE_HEAP_STORE(dest, value, bytes, isFloat) {
+#if SAFE_HEAP_LOG
+  Module.print('SAFE_HEAP store: ' + [dest, value, bytes, isFloat]);
+#endif
+  assert(dest > 0, 'segmentation fault');
+  assert(dest % bytes === 0);
+  setValue(dest, value, getSafeHeapType(bytes, isFloat), 1);
+}
+
+function SAFE_HEAP_LOAD(dest, bytes, isFloat) {
+#if SAFE_HEAP_LOG
+  Module.print('SAFE_HEAP load: ' + [dest, bytes, isFloat]);
+#endif
+  assert(dest > 0, 'segmentation fault');
+  assert(dest % bytes === 0);
+  return getValue(dest, getSafeHeapType(bytes, isFloat), 1);
+}
+
+#endif
 #endif
 
 #if CHECK_HEAP_ALIGN

src/runtime.js

@@ -49,7 +49,7 @@ var RuntimeGenerator = {
   stackExit: function(initial, force) {
     if (initial === 0 && SKIP_STACK_IN_SMALL && !force) return '';
     var ret = '';
-    if (SAFE_HEAP) {
+    if (SAFE_HEAP && !ASM_JS) {
       ret += 'var i = sp; while ((i|0) < (STACKTOP|0)) { SAFE_HEAP_CLEAR(i|0); i = (i+1)|0 }';
     }
     return ret += 'STACKTOP=sp';

tests/test_core.py

@@ -1486,7 +1486,7 @@ class T(RunnerCore): # Short name, to make it more fun to use manually on the co
 
   def test_segfault(self):
     if self.emcc_args is None: return self.skip('SAFE_HEAP without ta2 means we check types too, which hide segfaults')
-    if Settings.ASM_JS: return self.skip('asm does not support safe heap')
+    if os.environ.get('EMCC_FAST_COMPILER') == '1' and '-O2' not in self.emcc_args: return self.skip('todo in non-jsopts-enabled fastcomp')
 
     Settings.SAFE_HEAP = 1
 

tools/js-optimizer.js

@@ -3888,6 +3888,104 @@ function outline(ast) {
   });
 }
 
+function safeHeap(ast) {
+  function fixPtr(ptr, heap) {
+    switch (heap) {
+      case 'HEAP8':   case 'HEAPU8': break;
+      case 'HEAP16':  case 'HEAPU16': {
+        if (ptr[0] === 'binary') {
+          assert(ptr[1] === '>>' && ptr[3][0] === 'num' && ptr[3][1] === 1);
+          ptr = ptr[2]; // skip the shift
+        } else {
+          ptr = ['binary', '*', ptr, ['num', 2]]; // was unshifted, convert to absolute address
+        }
+        break;
+      }
+      case 'HEAP32':  case 'HEAPU32': {
+        if (ptr[0] === 'binary') {
+          assert(ptr[1] === '>>' && ptr[3][0] === 'num' && ptr[3][1] === 2);
+          ptr = ptr[2]; // skip the shift
+        } else {
+          ptr = ['binary', '*', ptr, ['num', 4]]; // was unshifted, convert to absolute address
+        }
+        break;
+      }
+      case 'HEAPF32': {
+        if (ptr[0] === 'binary') {
+          assert(ptr[1] === '>>' && ptr[3][0] === 'num' && ptr[3][1] === 2);
+          ptr = ptr[2]; // skip the shift
+        } else {
+          ptr = ['binary', '*', ptr, ['num', 4]]; // was unshifted, convert to absolute address
+        }
+        break;
+      }
+      case 'HEAPF64': {
+        if (ptr[0] === 'binary') {
+          assert(ptr[1] === '>>' && ptr[3][0] === 'num' && ptr[3][1] === 3);
+          ptr = ptr[2]; // skip the shift
+        } else {
+          ptr = ['binary', '*', ptr, ['num', 8]]; // was unshifted, convert to absolute address
+        }
+        break;
+      }
+      default: throw 'bad heap ' + heap;
+    }
+    ptr = ['binary', '|', ptr, ['num', 0]];
+    return ptr;
+  }
+  traverseGenerated(ast, function(node, type) {
+    if (type === 'assign') {
+      if (node[1] === true && node[2][0] === 'sub') {
+        var heap = node[2][1][1];
+        var ptr = fixPtr(node[2][2], heap);
+        var value = node[3];
+        // SAFE_HEAP_STORE(ptr, value, bytes, isFloat) 
+        switch (heap) {
+          case 'HEAP8':   case 'HEAPU8': {
+            return ['call', ['name', 'SAFE_HEAP_STORE'], [ptr, makeAsmCoercion(value, ASM_INT), ['num', 1], ['num', '0']]];
+          }
+          case 'HEAP16':  case 'HEAPU16': {
+            return ['call', ['name', 'SAFE_HEAP_STORE'], [ptr, makeAsmCoercion(value, ASM_INT), ['num', 2], ['num', '0']]];
+          }
+          case 'HEAP32':  case 'HEAPU32': {
+            return ['call', ['name', 'SAFE_HEAP_STORE'], [ptr, makeAsmCoercion(value, ASM_INT), ['num', 4], ['num', '0']]];
+          }
+          case 'HEAPF32': {
+            return ['call', ['name', 'SAFE_HEAP_STORE'], [ptr, makeAsmCoercion(value, ASM_FLOAT), ['num', 4], ['num', '1']]];
+          }
+          case 'HEAPF64': {
+            return ['call', ['name', 'SAFE_HEAP_STORE'], [ptr, makeAsmCoercion(value, ASM_DOUBLE), ['num', 8], ['num', '1']]];
+          }
+          default: throw 'bad heap ' + heap;
+        }
+      }
+    } else if (type === 'sub') {
+      var heap = node[1][1];
+      if (heap[0] !== 'H') return;
+      var ptr = fixPtr(node[2], heap);
+      // SAFE_HEAP_LOAD(ptr, bytes, isFloat) 
+      switch (heap) {
+        case 'HEAP8':   case 'HEAPU8': {
+          return makeAsmCoercion(['call', ['name', 'SAFE_HEAP_LOAD'], [ptr, ['num', 1], ['num', '0']]], ASM_INT);
+        }
+        case 'HEAP16':  case 'HEAPU16': {
+          return makeAsmCoercion(['call', ['name', 'SAFE_HEAP_LOAD'], [ptr, ['num', 2], ['num', '0']]], ASM_INT);
+        }
+        case 'HEAP32':  case 'HEAPU32': {
+          return makeAsmCoercion(['call', ['name', 'SAFE_HEAP_LOAD'], [ptr, ['num', 4], ['num', '0']]], ASM_INT);
+        }
+        case 'HEAPF32': {
+          return makeAsmCoercion(['call', ['name', 'SAFE_HEAP_LOAD'], [ptr, ['num', 4], ['num', '1']]], ASM_FLOAT);
+        }
+        case 'HEAPF64': {
+          return makeAsmCoercion(['call', ['name', 'SAFE_HEAP_LOAD'], [ptr, ['num', 8], ['num', '1']]], ASM_DOUBLE);
+        }
+        default: throw 'bad heap ' + heap;
+      }
+    }
+  });
+}
+
 // Last pass utilities
 
 // Change +5 to DOT$ZERO(5). We then textually change 5 to 5.0 (uglify's ast cannot differentiate between 5 and 5.0 directly)
@@ -3978,6 +4076,7 @@ function asmLastOpts(ast) {
 var minifyWhitespace = false, printMetadata = true, asm = false, last = false;
 
 var passes = {
+  // passes
   dumpAst: dumpAst,
   dumpSrc: dumpSrc,
   unGlobalize: unGlobalize,
@@ -3996,6 +4095,9 @@ var passes = {
   minifyLocals: minifyLocals,
   relocate: relocate,
   outline: outline,
+  safeHeap: safeHeap,
+
+  // flags
   minifyWhitespace: function() { minifyWhitespace = true },
   noPrintMetadata: function() { printMetadata = false },
   asm: function() { asm = true },