hphp/runtime/vm/jit/mutation.h

   1 /*
   2    +----------------------------------------------------------------------+
   3    | HipHop for PHP                                                       |
   4    +----------------------------------------------------------------------+
   5    | Copyright (c) 2010-present Facebook, Inc. (http://www.facebook.com)  |
   6    +----------------------------------------------------------------------+
   7    | This source file is subject to version 3.01 of the PHP license,      |
   8    | that is bundled with this package in the file LICENSE, and is        |
   9    | available through the world-wide-web at the following url:           |
  10    | http://www.php.net/license/3_01.txt                                  |
  11    | If you did not receive a copy of the PHP license and are unable to   |
  12    | obtain it through the world-wide-web, please send a note to          |
  13    | license@php.net so we can mail you a copy immediately.               |
  14    +----------------------------------------------------------------------+
  15 */
  16
  17 #ifndef incl_HPHP_JIT_MUTATION_H_
  18 #define incl_HPHP_JIT_MUTATION_H_
  19
  20 #include "hphp/runtime/vm/jit/block.h"
  21 #include "hphp/runtime/vm/jit/cfg.h"
  22
  23 namespace HPHP { namespace jit {
  24
  25 struct IRInstruction;
  26 struct IRUnit;
  27
  28 //////////////////////////////////////////////////////////////////////
  29
  30 /*
  31  * Utility routines for mutating the IR during optimization passes.
  32  */
  33
  34 //////////////////////////////////////////////////////////////////////
  35
  36 /*
  37  * Clone a range of IRInstructions into the front of a target block
  38  * (immediately after its DefLabel).
  39  *
  40  * Then, for any block reachable from `target', rewrite the sources of
  41  * any instructions that referred to the old destinations of the
  42  * cloned instructions so that they refer to the new destinations this
  43  * function created.
  44  *
  45  * Does not unlink the instructions from the source block.
  46  *
  47  * Pre: The range [first,last) may not contain control flow
  48  *      instructions.
  49  * Pre: blocks is in reverse postorder
  50  */
  51 void cloneToBlock(const BlockList& blocks,
  52                   IRUnit& unit,
  53                   Block::iterator first,
  54                   Block::iterator last,
  55                   Block* target);
  56
  57 /*
  58  * Move a range of IRInstructions to the front of a target block
  59  * (immediately after its DefLabel, but before its Marker).
  60  *
  61  * The instructions are unlinked from their current source block.
  62  *
  63  * Pre: The range [first,last) may not contain control flow
  64  * instructions.
  65  */
  66 void moveToBlock(Block::iterator first,
  67                  Block::iterator last,
  68                  Block* dst);
  69
  70 /*
  71  * Walk the cfg of the given unit, recomputing output types of all instructions
  72  * from their inputs.
  73  *
  74  * The new types of any changed SSATmps must be related to their old
  75  * types.  However, notice that the new types may result in
  76  * inconsistent operand types for instructions that are unreachable
  77  * (but not yet removed from the IR unit).
  78  */
  79 void reflowTypes(IRUnit&);
  80
  81 /*
  82  * Recomputes the output type of each of inst's dests.
  83  *
  84  * Returns: true if any of the instruction's dest types were changed.
  85  */
  86 bool retypeDests(IRInstruction*, const IRUnit*);
  87
  88 /*
  89  * Small pass that inserts AssertTypes on the taken edges of CheckType blocks
  90  * that may add type information about failing checks.  This pass is probably
  91  * worth running before refineTmps, because it may allow better types when
  92  * checks fail.
  93  *
  94  * (Note: the supplied block list need not be RPO-sorted.)
  95  */
  96 void insertNegativeAssertTypes(IRUnit&, const BlockList&);
  97
  98 /*
  99  * Pass that walks over the dominator tree and replaces uses of SSATmps that
 100  * have more-refined versions available with uses of the more refined versions.
 101  * This basically fixes patterns like this:
 102  *
 103  *    t1 = LdLoc<Cell>
 104  *    t2 = CheckType<Obj> t1 -> ...
 105  *    IncRef t1
 106  *
 107  * So that we can replace t1 with t2 in the parts of the code dominated by the
 108  * definition of t2.
 109  */
 110 void refineTmps(IRUnit&, const BlockList&, const IdomVector&);
 111
 112 /*
 113  * Insert a phi for inputs in blk. none of blk's input edges may be
 114  * critical, blk->numPreds() must be equal to inputs.size(), and
 115  * inputs.size() must be greater than 1.
 116  * If there's already a suitable phi, it will be returned.
 117  */
 118 SSATmp* insertPhi(IRUnit&, Block* blk, const jit::vector<SSATmp*>& inputs);
 119
 120 /*
 121  * Remove the i'th dest from `label' and all incoming Jmps, returning its
 122  * SSATmp*. May leave the DefLabel with 0 dests, in which case the instruction
 123  * may be deleted by the caller.
 124  */
 125 SSATmp* deletePhiDest(IRInstruction* label, unsigned i);
 126
 127 //////////////////////////////////////////////////////////////////////
 128
 129 }}
 130
 131 #endif