Add array bound checks to code generated for SwapElements. This fixes a bug t...

src/ia32/full-codegen-ia32.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
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 //
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@@ skipping 3090 matching lines @@
   __ j(not_equal, &slow_case);
 
   // Check that both indices are smis.
   __ mov(index_1, Operand(esp, 1 * kPointerSize));
   __ mov(index_2, Operand(esp, 0));
   __ mov(temp, index_1);
   __ or_(temp, Operand(index_2));
   __ test(temp, Immediate(kSmiTagMask));
   __ j(not_zero, &slow_case);
 
+  // Check that both indices are valid.
+  __ mov(temp, FieldOperand(object, JSArray::kLengthOffset));
+  __ cmp(temp, Operand(index_1));
+  __ j(less_equal, &slow_case);
+  __ cmp(temp, Operand(index_2));
+  __ j(less_equal, &slow_case);

[Lasse Reichstein, 2010/12/15 08:34:55]

I just noticed that there is no test for negative indices, which ofcourse
shouldn't be able to happen ... but trust is overrated.

Use below_equal here to do unsigned comparison (and trust that an array length
can never be negative :).
(You could also change the test above to test against (kSmiTagMask | <signbit
constant>), but that would probably use more bytes whereas changing the
condition is free).

Goes for all platforms.

[Karl Klose, 2010/12/15 09:11:45]

Done.

+
   // Bring addresses into index1 and index2.
   __ lea(index_1, CodeGenerator::FixedArrayElementOperand(elements, index_1));
   __ lea(index_2, CodeGenerator::FixedArrayElementOperand(elements, index_2));
 
   // Swap elements.  Use object and temp as scratch registers.
   __ mov(object, Operand(index_1, 0));
   __ mov(temp,   Operand(index_2, 0));
   __ mov(Operand(index_2, 0), object);
   __ mov(Operand(index_1, 0), temp);
 
@@ skipping 1053 matching lines @@
   // And return.
   __ ret(0);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32