Tim Starling
59 linhas
2.2 KiB
C++
59 linhas
2.2 KiB
C++
/*
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+----------------------------------------------------------------------+
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| HipHop for PHP |
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+----------------------------------------------------------------------+
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| Copyright (c) 2010-2013 Facebook, Inc. (http://www.facebook.com) |
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+----------------------------------------------------------------------+
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| This source file is subject to version 3.01 of the PHP license, |
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| that is bundled with this package in the file LICENSE, and is |
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| available through the world-wide-web at the following url: |
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| http://www.php.net/license/3_01.txt |
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| If you did not receive a copy of the PHP license and are unable to |
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| obtain it through the world-wide-web, please send a note to |
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| license@php.net so we can mail you a copy immediately. |
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+----------------------------------------------------------------------+
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*/
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/* The Peephole Optimizer
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* ======================
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*
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* The peephole optimizer performs some postprocessing on bytecode. Currently we
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* perform the following optimizations:
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*
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* - Jump rewriting: if we jump to a jump, we rewrite the original jump to just
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* directly jump to the final destination. We can handle long chains of jumps
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* and are careful about infinite loops and conditional jumps.
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* - PostInc/PostDec to PreInc/PreDec conversion: PostInc and PostDec are
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* necessarily slower than PreInc and PreDec, so when possible we convert
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* PostInc/PostDec to PreInc/PreDec.
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* - Conditional jump conversion: if a JmpZ uses an item from the stack which
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* was placed there by a Not, we remove the Not and replace the JmpZ with
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* JmpNZ. We likewise convert Not + JmpNZ to JmpZ.
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*/
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#ifndef incl_HPHP_COMPILER_ANALYSIS_PEEPHOLE_H_
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#define incl_HPHP_COMPILER_ANALYSIS_PEEPHOLE_H_
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#include "hphp/runtime/vm/unit.h"
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#include "hphp/runtime/vm/func.h"
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namespace HPHP { namespace Compiler {
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class MetaInfoBuilder;
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class Peephole {
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public:
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Peephole(UnitEmitter& ue, MetaInfoBuilder& metaInfo);
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private:
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void buildFuncTargets(FuncEmitter* fe);
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void buildJumpTargets();
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UnitEmitter& m_ue;
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hphp_hash_set<Offset> m_jumpTargets;
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};
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}}
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#endif
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