1 //===-- RTDyldMemoryManager.cpp - Memory manager for MC-JIT -----*- 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 // Implementation of the runtime dynamic memory manager base class. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "llvm/Config/config.h" 15 #include "llvm/ExecutionEngine/RTDyldMemoryManager.h" 16 #include "llvm/Support/DynamicLibrary.h" 17 #include "llvm/Support/ErrorHandling.h" 18 19 #include <cstdlib> 20 21 #ifdef __linux__ 22 // These includes used by RTDyldMemoryManager::getPointerToNamedFunction() 23 // for Glibc trickery. See comments in this function for more information. 24 #ifdef HAVE_SYS_STAT_H 25 #include <sys/stat.h> 26 #endif 27 #include <fcntl.h> 28 #include <unistd.h> 29 #endif 30 31 namespace llvm { 32 33 RTDyldMemoryManager::~RTDyldMemoryManager() {} 34 35 // Determine whether we can register EH tables. 36 #if (defined(__GNUC__) && !defined(__ARM_EABI__) && \ 37 !defined(__USING_SJLJ_EXCEPTIONS__)) 38 #define HAVE_EHTABLE_SUPPORT 1 39 #else 40 #define HAVE_EHTABLE_SUPPORT 0 41 #endif 42 43 #if HAVE_EHTABLE_SUPPORT 44 extern "C" void __register_frame(void*); 45 46 static const char *processFDE(const char *Entry) { 47 const char *P = Entry; 48 uint32_t Length = *((const uint32_t *)P); 49 P += 4; 50 uint32_t Offset = *((const uint32_t *)P); 51 if (Offset != 0) 52 __register_frame(const_cast<char *>(Entry)); 53 return P + Length; 54 } 55 #endif 56 57 void RTDyldMemoryManager::registerEHFrames(StringRef SectionData) { 58 #if HAVE_EHTABLE_SUPPORT 59 const char *P = SectionData.data(); 60 const char *End = SectionData.data() + SectionData.size(); 61 do { 62 P = processFDE(P); 63 } while(P != End); 64 #endif 65 } 66 67 static int jit_noop() { 68 return 0; 69 } 70 71 void *RTDyldMemoryManager::getPointerToNamedFunction(const std::string &Name, 72 bool AbortOnFailure) { 73 #if defined(__linux__) 74 //===--------------------------------------------------------------------===// 75 // Function stubs that are invoked instead of certain library calls 76 // 77 // Force the following functions to be linked in to anything that uses the 78 // JIT. This is a hack designed to work around the all-too-clever Glibc 79 // strategy of making these functions work differently when inlined vs. when 80 // not inlined, and hiding their real definitions in a separate archive file 81 // that the dynamic linker can't see. For more info, search for 82 // 'libc_nonshared.a' on Google, or read http://llvm.org/PR274. 83 if (Name == "stat") return (void*)(intptr_t)&stat; 84 if (Name == "fstat") return (void*)(intptr_t)&fstat; 85 if (Name == "lstat") return (void*)(intptr_t)&lstat; 86 if (Name == "stat64") return (void*)(intptr_t)&stat64; 87 if (Name == "fstat64") return (void*)(intptr_t)&fstat64; 88 if (Name == "lstat64") return (void*)(intptr_t)&lstat64; 89 if (Name == "atexit") return (void*)(intptr_t)&atexit; 90 if (Name == "mknod") return (void*)(intptr_t)&mknod; 91 #endif // __linux__ 92 93 // We should not invoke parent's ctors/dtors from generated main()! 94 // On Mingw and Cygwin, the symbol __main is resolved to 95 // callee's(eg. tools/lli) one, to invoke wrong duplicated ctors 96 // (and register wrong callee's dtors with atexit(3)). 97 // We expect ExecutionEngine::runStaticConstructorsDestructors() 98 // is called before ExecutionEngine::runFunctionAsMain() is called. 99 if (Name == "__main") return (void*)(intptr_t)&jit_noop; 100 101 const char *NameStr = Name.c_str(); 102 void *Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr); 103 if (Ptr) return Ptr; 104 105 // If it wasn't found and if it starts with an underscore ('_') character, 106 // try again without the underscore. 107 if (NameStr[0] == '_') { 108 Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr+1); 109 if (Ptr) return Ptr; 110 } 111 112 if (AbortOnFailure) 113 report_fatal_error("Program used external function '" + Name + 114 "' which could not be resolved!"); 115 return 0; 116 } 117 118 } // namespace llvm 119