hphp/hhbbc/eval-cell.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 #ifndef incl_HHBBC_EVAL_CELL_H_
  17 #define incl_HHBBC_EVAL_CELL_H_
  18
  19 #include <stdexcept>
  20 #include <exception>
  21
  22 #include <folly/ScopeGuard.h>
  23 #include <folly/Optional.h>
  24
  25 #include "hphp/runtime/base/array-data.h"
  26 #include "hphp/runtime/base/execution-context.h"
  27 #include "hphp/runtime/base/string-data.h"
  28 #include "hphp/runtime/base/tv-refcount.h"
  29 #include "hphp/runtime/vm/repo.h"
  30
  31 #include "hphp/hhbbc/options.h"
  32 #include "hphp/hhbbc/type-system.h"
  33
  34 namespace HPHP { namespace HHBBC {
  35
  36 //////////////////////////////////////////////////////////////////////
  37
  38 /*
  39  * When constant-evaluating certain operations, it's possible they
  40  * will return non-static objects, or throw exceptions (e.g. tvAdd()
  41  * with an array and an int).
  42  *
  43  * This routine converts these things back to types.  In the case of
  44  * an exception it returns TInitCell.
  45  */
  46 template<class Pred>
  47 folly::Optional<Type> eval_cell(Pred p) {
  48   try {
  49     assert(!RuntimeOption::EvalJit);
  50     ThrowAllErrorsSetter taes;
  51
  52     TypedValue c = p();
  53     if (isRefcountedType(c.m_type)) {
  54       if (c.m_type == KindOfString &&
  55           c.m_data.pstr->size() > Repo::get().stringLengthLimit()) {
  56         tvDecRefCountable(&c);
  57         return TStr;
  58       }
  59       tvAsVariant(&c).setEvalScalar();
  60     }
  61
  62     /*
  63      * We need to get rid of statics if we're not actually going to do
  64      * constant propagation.  When ConstantProp is on, the types we
  65      * create here can reflect that we'll be changing bytecode later
  66      * to actually make these into non-reference-counted SStr or
  67      * SArrs.  If we leave the bytecode alone, though, it generally
  68      * won't actually be static at runtime.
  69      */
  70     auto const t = from_cell(c);
  71     return options.ConstantProp ? t : loosen_staticness(t);
  72   } catch (const Object&) {
  73     return folly::none;
  74   } catch (const std::exception&) {
  75     return folly::none;
  76   } catch (...) {
  77     always_assert_flog(0, "a non-std::exception was thrown in eval_cell");
  78   }
  79 }
  80
  81 template<typename Pred>
  82 folly::Optional<typename std::result_of<Pred()>::type>
  83 eval_cell_value(Pred p) {
  84   try {
  85     ThrowAllErrorsSetter taes;
  86     return p();
  87   } catch (const Object&) {
  88     return folly::none;
  89   } catch (const std::exception&) {
  90     return folly::none;
  91   } catch (...) {
  92     always_assert_flog(0, "a non-std::exception was thrown in eval_cell_value");
  93   }
  94 }
  95
  96 //////////////////////////////////////////////////////////////////////
  97
  98 }}
  99
 100 #endif