[wasm] Fix bounds check for zero initial memory.

test/mjsunit/wasm/grow-memory.js

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Flags: --expose-wasm --expose-gc --stress-compaction
 
 load("test/mjsunit/wasm/wasm-constants.js");
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
 var kPageSize = 0x10000;
@@ skipping 161 matching lines @@
     assertEquals(20, peek());
   }
   for (offset = 19*kPageSize; offset < 19*kPageSize + 5; offset++) {
     assertTraps(kTrapMemOutOfBounds, poke);
     assertTraps(kTrapMemOutOfBounds, peek);
   }
 }
 
 testGrowMemoryReadWrite8();
 
-function testGrowMemoryZeroInitialSize() {
+function testGrowMemoryZeroInitialSize32() {
   var builder = genGrowMemoryBuilder();
   var module = builder.instantiate();
   var offset;
   function peek() { return module.exports.load(offset); }
   function poke(value) { return module.exports.store(offset, value); }
   function growMem(pages) { return module.exports.grow_memory(pages); }
 
   assertTraps(kTrapMemOutOfBounds, peek);
   assertTraps(kTrapMemOutOfBounds, poke);
 
   assertEquals(0, growMem(1));
 
   for(offset = 0; offset <= kPageSize - 4; offset++) {
     poke(20);
     assertEquals(20, peek());
   }
 
-  //TODO(gdeepti): Fix tests with correct write boundaries
-  //when runtime function is fixed.
+  for(offset = kPageSize - 3; offset <= kPageSize + 5; offset++) {
+    assertTraps(kTrapMemOutOfBounds, peek);
+  }
+}
+
+testGrowMemoryZeroInitialSize32();
+
+function testGrowMemoryZeroInitialSize16() {

[bradn, 2016/10/12 18:50:45]

Might be worth programatically generating all the sizes from like 0-128 by using
toString()
You'll have to do something special for int64 (maybe return xor or high and
low).

[gdeepti, 2016/10/13 08:43:00]

Added a TODO for now as I have to look into what needs to be done for sizes
larger than 32bit that throw type errors when exported to JS.

+  var builder = genGrowMemoryBuilder();
+  var module = builder.instantiate();
+  var offset;
+  function peek() { return module.exports.load16(offset); }
+  function poke(value) { return module.exports.store16(offset, value); }
+  function growMem(pages) { return module.exports.grow_memory(pages); }
+
+  assertTraps(kTrapMemOutOfBounds, peek);
+  assertTraps(kTrapMemOutOfBounds, poke);
+
+  assertEquals(0, growMem(1));
+
+  for(offset = 0; offset <= kPageSize - 2; offset++) {
+    poke(20);
+    assertEquals(20, peek());
+  }
+
+  for(offset = kPageSize - 1; offset <= kPageSize + 5; offset++) {
+    assertTraps(kTrapMemOutOfBounds, peek);
+  }
+}
+
+testGrowMemoryZeroInitialSize16();
+
+function testGrowMemoryZeroInitialSize8() {
+  var builder = genGrowMemoryBuilder();
+  var module = builder.instantiate();
+  var offset;
+  function peek() { return module.exports.load8(offset); }
+  function poke(value) { return module.exports.store8(offset, value); }
+  function growMem(pages) { return module.exports.grow_memory(pages); }
+
+  assertTraps(kTrapMemOutOfBounds, peek);
+  assertTraps(kTrapMemOutOfBounds, poke);
+
+  assertEquals(0, growMem(1));
+
+  for(offset = 0; offset <= kPageSize - 1; offset++) {
+    poke(20);
+    assertEquals(20, peek());
+  }
+
   for(offset = kPageSize; offset <= kPageSize + 5; offset++) {
     assertTraps(kTrapMemOutOfBounds, peek);
   }
 }
 
-testGrowMemoryZeroInitialSize();
+testGrowMemoryZeroInitialSize8();
 
 function testGrowMemoryTrapMaxPagesZeroInitialMemory() {
   var builder = genGrowMemoryBuilder();
   var module = builder.instantiate();
   var maxPages = 16385;
   function growMem(pages) { return module.exports.grow_memory(pages); }
   assertEquals(-1, growMem(maxPages));
 }
 
 testGrowMemoryTrapMaxPagesZeroInitialMemory();
@@ skipping 133 matching lines @@
     poke(0xaced);
     assertEquals(0xaced, peek());
   }
 
   for (offset = 4*kPageSize - 3; offset <= 4*kPageSize + 4; offset++) {
     assertTraps(kTrapMemOutOfBounds, poke);
   }
 }
 
 testGrowMemoryOutOfBoundsOffset();