MIPS: Make SubStringStub more robust with unsafe arguments.
Port r11349 (5b381a). BUG= TEST= Review URL: https://chromiumcodereview.appspot.com/10107025 Patch from Daniel Kalmar <kalmard@homejinni.com>. git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11367 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
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@ -6095,37 +6095,11 @@ void SubStringStub::Generate(MacroAssembler* masm) {
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// a2: result string length
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__ lw(t0, FieldMemOperand(v0, String::kLengthOffset));
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__ sra(t0, t0, 1);
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// Return original string.
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__ Branch(&return_v0, eq, a2, Operand(t0));
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Label result_longer_than_two;
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// Check for special case of two character ASCII string, in which case
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// we do a lookup in the symbol table first.
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__ li(t0, 2);
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__ Branch(&result_longer_than_two, gt, a2, Operand(t0));
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__ Branch(&runtime, lt, a2, Operand(t0));
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__ JumpIfInstanceTypeIsNotSequentialAscii(a1, a1, &runtime);
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// Get the two characters forming the sub string.
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__ Addu(v0, v0, Operand(a3));
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__ lbu(a3, FieldMemOperand(v0, SeqAsciiString::kHeaderSize));
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__ lbu(t0, FieldMemOperand(v0, SeqAsciiString::kHeaderSize + 1));
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// Try to lookup two character string in symbol table.
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Label make_two_character_string;
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StringHelper::GenerateTwoCharacterSymbolTableProbe(
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masm, a3, t0, a1, t1, t2, t3, t4, &make_two_character_string);
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__ jmp(&return_v0);
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// a2: result string length.
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// a3: two characters combined into halfword in little endian byte order.
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__ bind(&make_two_character_string);
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__ AllocateAsciiString(v0, a2, t0, t1, t4, &runtime);
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__ sh(a3, FieldMemOperand(v0, SeqAsciiString::kHeaderSize));
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__ jmp(&return_v0);
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__ bind(&result_longer_than_two);
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// Longer than original string's length or negative: unsafe arguments.
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__ Branch(&runtime, hi, a2, Operand(t0));
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// Shorter than original string's length: an actual substring.
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// Deal with different string types: update the index if necessary
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// and put the underlying string into t1.
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