Better handling of allocation alignment in generated code

Calculate the aligned size of strings when allocating from generated code using kObjectAlignmentMask

Add native code assert to make sure allocation from generated code keeps alignment.
Review URL: http://codereview.chromium.org/462025

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@3415 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/ia32/codegen-ia32.cc

@@ -7091,7 +7091,7 @@ void GenericBinaryOpStub::Generate(MacroAssembler* masm) {
   switch (op_) {
     case Token::ADD: {
       // Test for string arguments before calling runtime.
-      Label not_strings, both_strings, not_string1, string1;
+      Label not_strings, not_string1, string1;
       Result answer;
       __ mov(eax, Operand(esp, 2 * kPointerSize));  // First argument.
       __ mov(edx, Operand(esp, 1 * kPointerSize));  // Second argument.

src/ia32/macro-assembler-ia32.cc

@@ -687,6 +687,11 @@ void MacroAssembler::LoadAllocationTopHelper(Register result,
 
 void MacroAssembler::UpdateAllocationTopHelper(Register result_end,
                                                Register scratch) {
+  if (FLAG_debug_code) {
+    test(result_end, Immediate(kObjectAlignmentMask));
+    Check(zero, "Unaligned allocation in new space");
+  }
+
   ExternalReference new_space_allocation_top =
       ExternalReference::new_space_allocation_top_address();
 
@@ -826,15 +831,18 @@ void MacroAssembler::AllocateTwoByteString(Register result,
                                            Register scratch2,
                                            Register scratch3,
                                            Label* gc_required) {
-  // Calculate the number of words needed for the number of characters in the
-  // string
+  // Calculate the number of bytes needed for the characters in the string while
+  // observing object alignment.
+  ASSERT((SeqTwoByteString::kHeaderSize & kObjectAlignmentMask) == 0);
   mov(scratch1, length);
-  add(Operand(scratch1), Immediate(1));
-  shr(scratch1, 1);
+  ASSERT(kShortSize == 2);
+  shl(scratch1, 1);
+  add(Operand(scratch1), Immediate(kObjectAlignmentMask));
+  and_(Operand(scratch1), Immediate(~kObjectAlignmentMask));
 
   // Allocate two byte string in new space.
   AllocateInNewSpace(SeqTwoByteString::kHeaderSize,
-                     times_4,
+                     times_1,
                      scratch1,
                      result,
                      scratch2,
@@ -857,15 +865,17 @@ void MacroAssembler::AllocateAsciiString(Register result,
                                          Register scratch2,
                                          Register scratch3,
                                          Label* gc_required) {
-  // Calculate the number of words needed for the number of characters in the
-  // string
+  // Calculate the number of bytes needed for the characters in the string while
+  // observing object alignment.
+  ASSERT((SeqAsciiString::kHeaderSize & kObjectAlignmentMask) == 0);
   mov(scratch1, length);
-  add(Operand(scratch1), Immediate(3));
-  shr(scratch1, 2);
+  ASSERT(kCharSize == 1);
+  add(Operand(scratch1), Immediate(kObjectAlignmentMask));
+  and_(Operand(scratch1), Immediate(~kObjectAlignmentMask));
 
   // Allocate ascii string in new space.
   AllocateInNewSpace(SeqAsciiString::kHeaderSize,
-                     times_4,
+                     times_1,
                      scratch1,
                      result,
                      scratch2,
@@ -1383,11 +1393,15 @@ void MacroAssembler::Abort(const char* msg) {
     RecordComment(msg);
   }
 #endif
+  // Disable stub call restrictions to always allow cals to abort.
+  set_allow_stub_calls(true);
+
   push(eax);
   push(Immediate(p0));
   push(Immediate(reinterpret_cast<intptr_t>(Smi::FromInt(p1 - p0))));
   CallRuntime(Runtime::kAbort, 2);
   // will not return here
+  int3();
 }