LCOV - code coverage report
Current view: top level - include/llvm/ExecutionEngine/Orc - ExecutionUtils.h (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 25 27 92.6 %
Date: 2017-09-14 15:23:50 Functions: 7 7 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===- ExecutionUtils.h - Utilities for executing code in Orc ---*- C++ -*-===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : //
      10             : // Contains utilities for executing code in Orc.
      11             : //
      12             : //===----------------------------------------------------------------------===//
      13             : 
      14             : #ifndef LLVM_EXECUTIONENGINE_ORC_EXECUTIONUTILS_H
      15             : #define LLVM_EXECUTIONENGINE_ORC_EXECUTIONUTILS_H
      16             : 
      17             : #include "llvm/ADT/StringMap.h"
      18             : #include "llvm/ADT/iterator_range.h"
      19             : #include "llvm/ExecutionEngine/JITSymbol.h"
      20             : #include "llvm/ExecutionEngine/RuntimeDyld.h"
      21             : #include "llvm/ExecutionEngine/Orc/OrcError.h"
      22             : #include <algorithm>
      23             : #include <cstdint>
      24             : #include <string>
      25             : #include <vector>
      26             : #include <utility>
      27             : 
      28             : namespace llvm {
      29             : 
      30             : class ConstantArray;
      31             : class GlobalVariable;
      32             : class Function;
      33             : class Module;
      34             : class Value;
      35             : 
      36             : namespace orc {
      37             : 
      38             : /// @brief This iterator provides a convenient way to iterate over the elements
      39             : ///        of an llvm.global_ctors/llvm.global_dtors instance.
      40             : ///
      41             : ///   The easiest way to get hold of instances of this class is to use the
      42             : /// getConstructors/getDestructors functions.
      43             : class CtorDtorIterator {
      44             : public:
      45             :   /// @brief Accessor for an element of the global_ctors/global_dtors array.
      46             :   ///
      47             :   ///   This class provides a read-only view of the element with any casts on
      48             :   /// the function stripped away.
      49             :   struct Element {
      50             :     Element(unsigned Priority, Function *Func, Value *Data)
      51           1 :       : Priority(Priority), Func(Func), Data(Data) {}
      52             : 
      53             :     unsigned Priority;
      54             :     Function *Func;
      55             :     Value *Data;
      56             :   };
      57             : 
      58             :   /// @brief Construct an iterator instance. If End is true then this iterator
      59             :   ///        acts as the end of the range, otherwise it is the beginning.
      60             :   CtorDtorIterator(const GlobalVariable *GV, bool End);
      61             : 
      62             :   /// @brief Test iterators for equality.
      63             :   bool operator==(const CtorDtorIterator &Other) const;
      64             : 
      65             :   /// @brief Test iterators for inequality.
      66             :   bool operator!=(const CtorDtorIterator &Other) const;
      67             : 
      68             :   /// @brief Pre-increment iterator.
      69             :   CtorDtorIterator& operator++();
      70             : 
      71             :   /// @brief Post-increment iterator.
      72             :   CtorDtorIterator operator++(int);
      73             : 
      74             :   /// @brief Dereference iterator. The resulting value provides a read-only view
      75             :   ///        of this element of the global_ctors/global_dtors list.
      76             :   Element operator*() const;
      77             : 
      78             : private:
      79             :   const ConstantArray *InitList;
      80             :   unsigned I;
      81             : };
      82             : 
      83             : /// @brief Create an iterator range over the entries of the llvm.global_ctors
      84             : ///        array.
      85             : iterator_range<CtorDtorIterator> getConstructors(const Module &M);
      86             : 
      87             : /// @brief Create an iterator range over the entries of the llvm.global_ctors
      88             : ///        array.
      89             : iterator_range<CtorDtorIterator> getDestructors(const Module &M);
      90             : 
      91             : /// @brief Convenience class for recording constructor/destructor names for
      92             : ///        later execution.
      93             : template <typename JITLayerT>
      94          25 : class CtorDtorRunner {
      95             : public:
      96             :   /// @brief Construct a CtorDtorRunner for the given range using the given
      97             :   ///        name mangling function.
      98          22 :   CtorDtorRunner(std::vector<std::string> CtorDtorNames,
      99             :                  typename JITLayerT::ModuleHandleT H)
     100          44 :       : CtorDtorNames(std::move(CtorDtorNames)), H(H) {}
     101             : 
     102             :   /// @brief Run the recorded constructors/destructors through the given JIT
     103             :   ///        layer.
     104          22 :   Error runViaLayer(JITLayerT &JITLayer) const {
     105             :     using CtorDtorTy = void (*)();
     106             : 
     107          89 :     for (const auto &CtorDtorName : CtorDtorNames)
     108           2 :       if (auto CtorDtorSym = JITLayer.findSymbolIn(H, CtorDtorName, false)) {
     109           3 :         if (auto AddrOrErr = CtorDtorSym.getAddress()) {
     110           1 :           CtorDtorTy CtorDtor =
     111           1 :             reinterpret_cast<CtorDtorTy>(static_cast<uintptr_t>(*AddrOrErr));
     112           1 :           CtorDtor();
     113             :         } else
     114           0 :           return AddrOrErr.takeError();
     115             :       } else {
     116           0 :         if (auto Err = CtorDtorSym.takeError())
     117             :           return Err;
     118             :         else
     119             :           return make_error<JITSymbolNotFound>(CtorDtorName);
     120             :       }
     121          66 :     return Error::success();
     122             :   }
     123             : 
     124             : private:
     125             :   std::vector<std::string> CtorDtorNames;
     126             :   typename JITLayerT::ModuleHandleT H;
     127             : };
     128             : 
     129             : /// @brief Support class for static dtor execution. For hosted (in-process) JITs
     130             : ///        only!
     131             : ///
     132             : ///   If a __cxa_atexit function isn't found C++ programs that use static
     133             : /// destructors will fail to link. However, we don't want to use the host
     134             : /// process's __cxa_atexit, because it will schedule JIT'd destructors to run
     135             : /// after the JIT has been torn down, which is no good. This class makes it easy
     136             : /// to override __cxa_atexit (and the related __dso_handle).
     137             : ///
     138             : ///   To use, clients should manually call searchOverrides from their symbol
     139             : /// resolver. This should generally be done after attempting symbol resolution
     140             : /// inside the JIT, but before searching the host process's symbol table. When
     141             : /// the client determines that destructors should be run (generally at JIT
     142             : /// teardown or after a return from main), the runDestructors method should be
     143             : /// called.
     144          20 : class LocalCXXRuntimeOverrides {
     145             : public:
     146             :   /// Create a runtime-overrides class.
     147             :   template <typename MangleFtorT>
     148          30 :   LocalCXXRuntimeOverrides(const MangleFtorT &Mangle) {
     149          60 :     addOverride(Mangle("__dso_handle"), toTargetAddress(&DSOHandleOverride));
     150          60 :     addOverride(Mangle("__cxa_atexit"), toTargetAddress(&CXAAtExitOverride));
     151          10 :   }
     152             : 
     153             :   /// Search overrided symbols.
     154           9 :   JITEvaluatedSymbol searchOverrides(const std::string &Name) {
     155          18 :     auto I = CXXRuntimeOverrides.find(Name);
     156          27 :     if (I != CXXRuntimeOverrides.end())
     157           6 :       return JITEvaluatedSymbol(I->second, JITSymbolFlags::Exported);
     158             :     return nullptr;
     159             :   }
     160             : 
     161             :   /// Run any destructors recorded by the overriden __cxa_atexit function
     162             :   /// (CXAAtExitOverride).
     163             :   void runDestructors();
     164             : 
     165             : private:
     166             :   template <typename PtrTy>
     167             :   JITTargetAddress toTargetAddress(PtrTy* P) {
     168          20 :     return static_cast<JITTargetAddress>(reinterpret_cast<uintptr_t>(P));
     169             :   }
     170             : 
     171          20 :   void addOverride(const std::string &Name, JITTargetAddress Addr) {
     172         100 :     CXXRuntimeOverrides.insert(std::make_pair(Name, Addr));
     173          20 :   }
     174             : 
     175             :   StringMap<JITTargetAddress> CXXRuntimeOverrides;
     176             : 
     177             :   using DestructorPtr = void (*)(void *);
     178             :   using CXXDestructorDataPair = std::pair<DestructorPtr, void *>;
     179             :   using CXXDestructorDataPairList = std::vector<CXXDestructorDataPair>;
     180             :   CXXDestructorDataPairList DSOHandleOverride;
     181             :   static int CXAAtExitOverride(DestructorPtr Destructor, void *Arg,
     182             :                                void *DSOHandle);
     183             : };
     184             : 
     185             : } // end namespace orc
     186             : 
     187             : } // end namespace llvm
     188             : 
     189             : #endif // LLVM_EXECUTIONENGINE_ORC_EXECUTIONUTILS_H

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