Reviewers: Mads Ager, Description: 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. Please review this at http://codereview.chromium.org/462025 SVN Base: http://v8.googlecode.com/svn/branches/bleeding_edge/ Affected files: M src/ia32/codegen-ia32.cc M src/ia32/macro-assembler-ia32.cc Index: src/ia32/codegen-ia32.cc =================================================================== --- src/ia32/codegen-ia32.cc (revision 3400) +++ src/ia32/codegen-ia32.cc (working copy) @@ -7041,7 +7041,7 @@ 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. Index: src/ia32/macro-assembler-ia32.cc =================================================================== --- src/ia32/macro-assembler-ia32.cc (revision 3400) +++ src/ia32/macro-assembler-ia32.cc (working copy) @@ -687,6 +687,11 @@ void MacroAssembler::UpdateAllocationTopHelper(Register result_end, Register scratch) { +#ifdef DEBUG + test(result_end, Immediate(kObjectAlignmentMask)); + Check(zero, "Unaligned allocation in new space"); +#endif + ExternalReference new_space_allocation_top = ExternalReference::new_space_allocation_top_address(); @@ -826,15 +831,18 @@ 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 @@ 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 @@ 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(); } -- v8-dev mailing list [email protected] http://groups.google.com/group/v8-dev
