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	1	/*
	2	* Copyright (C) 2013 Apple Inc. All rights reserved.
	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
	12	*
	13	* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
	14	* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	15	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	16	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
	17	* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
	18	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
	19	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
	20	* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
	21	* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	22	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	23	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	24	*/
	25
	26	#include "config.h"
	27	#include "PreciseJumpTargets.h"
	28
	29	#include "JSCInlines.h"
	30
	31	namespace JSC {
	32
	33	template <size_t vectorSize>
	34	static void getJumpTargetsForBytecodeOffset(CodeBlock* codeBlock, Interpreter* interpreter, Instruction* instructionsBegin, unsigned bytecodeOffset, Vector<unsigned, vectorSize>& out)
	35	{
	36	OpcodeID opcodeID = interpreter->getOpcodeID(instructionsBegin[bytecodeOffset].u.opcode);
	37	Instruction* current = instructionsBegin + bytecodeOffset;
	38	switch (opcodeID) {
	39	case op_jmp:
	40	out.append(bytecodeOffset + current[1].u.operand);
	41	break;
	42	case op_jtrue:
	43	case op_jfalse:
	44	case op_jeq_null:
	45	case op_jneq_null:
	46	out.append(bytecodeOffset + current[2].u.operand);
	47	break;
	48	case op_jneq_ptr:
	49	case op_jless:
	50	case op_jlesseq:
	51	case op_jgreater:
	52	case op_jgreatereq:
	53	case op_jnless:
	54	case op_jnlesseq:
	55	case op_jngreater:
	56	case op_jngreatereq:
	57	out.append(bytecodeOffset + current[3].u.operand);
	58	break;
	59	case op_switch_imm:
	60	case op_switch_char: {
	61	SimpleJumpTable& table = codeBlock->switchJumpTable(current[1].u.operand);
	62	for (unsigned i = table.branchOffsets.size(); i--;)
	63	out.append(bytecodeOffset + table.branchOffsets[i]);
	64	out.append(bytecodeOffset + current[2].u.operand);
	65	break;
	66	}
	67	case op_switch_string: {
	68	StringJumpTable& table = codeBlock->stringSwitchJumpTable(current[1].u.operand);
	69	StringJumpTable::StringOffsetTable::iterator iter = table.offsetTable.begin();
	70	StringJumpTable::StringOffsetTable::iterator end = table.offsetTable.end();
	71	for (; iter != end; ++iter)
	72	out.append(bytecodeOffset + iter->value.branchOffset);
	73	out.append(bytecodeOffset + current[2].u.operand);
	74	break;
	75	}
	76	case op_check_has_instance:
	77	out.append(bytecodeOffset + current[4].u.operand);
	78	break;
	79	case op_loop_hint:
	80	out.append(bytecodeOffset);
	81	break;
	82	default:
	83	break;
	84	}
	85	}
	86
	87	void computePreciseJumpTargets(CodeBlock* codeBlock, Vector<unsigned, 32>& out)
	88	{
	89	ASSERT(out.isEmpty());
	90
	91	// We will derive a superset of the jump targets that the code block thinks it has.
	92	// So, if the code block claims there are none, then we are done.
	93	if (!codeBlock->numberOfJumpTargets())
	94	return;
	95
	96	for (unsigned i = codeBlock->numberOfExceptionHandlers(); i--;)
	97	out.append(codeBlock->exceptionHandler(i).target);
	98
	99	Interpreter* interpreter = codeBlock->vm()->interpreter;
	100	Instruction* instructionsBegin = codeBlock->instructions().begin();
	101	unsigned instructionCount = codeBlock->instructions().size();
	102	for (unsigned bytecodeOffset = 0; bytecodeOffset < instructionCount;) {
	103	OpcodeID opcodeID = interpreter->getOpcodeID(instructionsBegin[bytecodeOffset].u.opcode);
	104	getJumpTargetsForBytecodeOffset(codeBlock, interpreter, instructionsBegin, bytecodeOffset, out);
	105	bytecodeOffset += opcodeLengths[opcodeID];
	106	}
	107
	108	std::sort(out.begin(), out.end());
	109
	110	// We will have duplicates, and we must remove them.
	111	unsigned toIndex = 0;
	112	unsigned fromIndex = 0;
	113	unsigned lastValue = UINT_MAX;
	114	while (fromIndex < out.size()) {
	115	unsigned value = out[fromIndex++];
	116	if (value == lastValue)
	117	continue;
	118	out[toIndex++] = value;
	119	lastValue = value;
	120	}
	121	out.resize(toIndex);
	122	}
	123
	124	void findJumpTargetsForBytecodeOffset(CodeBlock* codeBlock, unsigned bytecodeOffset, Vector<unsigned, 1>& out)
	125	{
	126	Interpreter* interpreter = codeBlock->vm()->interpreter;
	127	Instruction* instructionsBegin = codeBlock->instructions().begin();
	128	getJumpTargetsForBytecodeOffset(codeBlock, interpreter, instructionsBegin, bytecodeOffset, out);
	129	}
	130
	131	} // namespace JSC
	132