hphp/runtime/vm/jit/insert-asserts.cpp

   1 /*
   2    +----------------------------------------------------------------------+
   3    | HipHop for PHP                                                       |
   4    +----------------------------------------------------------------------+
   5    | Copyright (c) 2010-2014 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 #include "hphp/runtime/vm/jit/opt.h"
  17
  18 #include <iterator>
  19
  20 #include "hphp/runtime/vm/jit/ir-instruction.h"
  21 #include "hphp/runtime/vm/jit/block.h"
  22 #include "hphp/runtime/vm/jit/ir-unit.h"
  23 #include "hphp/runtime/vm/jit/cfg.h"
  24
  25 namespace HPHP { namespace jit {
  26
  27 namespace {
  28
  29 //////////////////////////////////////////////////////////////////////
  30
  31 /*
  32  * Insert `inst' after `definer'.
  33  *
  34  * If `definer' ends its block, it must have a fallthrough block, and `inst'
  35  * will be inserted at the beginning of that block, as long as the block has no
  36  * other predecessors.
  37  *
  38  * Returns: true if it inserted the intruction.
  39  */
  40 bool insertAfter(IRInstruction* definer, IRInstruction* inst) {
  41   assertx(!definer->isTerminal());
  42   if (definer->isControlFlow()) {
  43     assertx(definer->next());
  44     if (definer->next()->numPreds() == 1) {
  45       definer->next()->prepend(inst);
  46       return true;
  47     }
  48     return false;
  49   }
  50
  51   auto const block = definer->block();
  52   auto const pos = block->iteratorTo(definer);
  53   block->insert(std::next(pos), inst);
  54   return true;
  55 }
  56
  57 /*
  58  * Insert a DbgAssertRefCount instruction after each place we define a
  59  * maybe-refcounted SSATmp.
  60  */
  61 void insertRefCountAsserts(IRUnit& unit, IRInstruction& inst) {
  62   for (auto dst : inst.dsts()) {
  63     auto const t = dst->type();
  64     if (t <= TGen && t.maybe(TCounted)) {
  65       insertAfter(&inst, unit.gen(DbgAssertRefCount, inst.marker(), dst));
  66     }
  67   }
  68 }
  69
  70 void insertStkAssert(IRUnit& unit,
  71                      IRInstruction* where,
  72                      SSATmp* sp,
  73                      IRSPOffset off) {
  74   auto const addr = unit.gen(
  75     LdStkAddr,
  76     where->marker(),
  77     TPtrToStkGen,
  78     IRSPOffsetData { off },
  79     sp
  80   );
  81   if (!insertAfter(where, addr)) return;
  82   auto const check = unit.gen(DbgAssertPtr, where->marker(), addr->dst());
  83   insertAfter(addr, check);
  84 }
  85
  86 //////////////////////////////////////////////////////////////////////
  87
  88 void visit(IRUnit& unit, Block* block) {
  89   for (auto it = block->begin(); it != block->end();) {
  90     auto& inst = *it;
  91     ++it;
  92
  93     switch (inst.op()) {
  94     case Call:
  95       {
  96         auto const extra = inst.extra<Call>();
  97         insertStkAssert(unit, &inst, inst.src(0),
  98           extra->spOffset + extra->numParams + kNumActRecCells - 1);
  99       }
 100       break;
 101     default:
 102       insertRefCountAsserts(unit, inst);
 103       break;
 104     }
 105   }
 106 }
 107
 108 //////////////////////////////////////////////////////////////////////
 109
 110 }
 111
 112 void insertAsserts(IRUnit& unit) {
 113   // Note: it doesn't matter what order we visit the blocks for this pass.
 114   for (auto& block : poSortCfg(unit)) visit(unit, block);
 115 }
 116
 117 //////////////////////////////////////////////////////////////////////
 118
 119 }}