Eliminate the static constructors and locks from DynamicLibrary.cpp.

This fixes PR4512 and eliminating static ctors is always good.  Losing
thread safety is unfortunate, but the code is just incredibly poorly
designed.

If someone is interested, the "right" solution is to split
DynamicLibrary.cpp into two separate pieces: a stateless piece in
libsystem, and a simple support file in libsupport that has the
"state" (e.g.  AddSymbol) in managed static objects.

Doing this would both fix memory leaks we already have, as well as make
the code thread safe again.  it would also make sense to move all the
unix specific code in System/DynamicLibrary.cpp into
System/Unix/DynamicLibrary.inc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74927 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/System/DynamicLibrary.h b/include/llvm/System/DynamicLibrary.h
index f04734a6f9bcd8fe98c7262c97cccd90ce84655a..ac58407a194d6d523b4736e62199e834357ba968 100644 (file)
--- a/include/llvm/System/DynamicLibrary.h
+++ b/include/llvm/System/DynamicLibrary.h
@@ -36,6 +36,9 @@ namespace sys {
     /// and will only be unloaded when the program terminates.  This returns
     /// false on success or returns true and fills in *ErrMsg on failure.
     /// @brief Open a dynamic library permanently.
+    ///
+    /// NOTE: This function is not thread safe.
+    ///
     static bool LoadLibraryPermanently(const char *filename,
                                        std::string *ErrMsg = 0);
 
@@ -46,9 +49,15 @@ namespace sys {
     /// as ephemerally loaded libraries (constructors).
     /// @throws std::string on error.
     /// @brief Search through libraries for address of a symbol
+    ///
+    /// NOTE: This function is not thread safe.
+    ///
     static void *SearchForAddressOfSymbol(const char *symbolName);
 
     /// @brief Convenience function for C++ophiles.
+    ///
+    /// NOTE: This function is not thread safe.
+    ///
     static void *SearchForAddressOfSymbol(const std::string &symbolName) {
       return SearchForAddressOfSymbol(symbolName.c_str());
     }
@@ -57,9 +66,15 @@ namespace sys {
     /// value \p symbolValue.  These symbols are searched before any
     /// libraries.
     /// @brief Add searchable symbol/value pair.
+    ///
+    /// NOTE: This function is not thread safe.
+    ///
     static void AddSymbol(const char *symbolName, void *symbolValue);
 
     /// @brief Convenience function for C++ophiles.
+    ///
+    /// NOTE: This function is not thread safe.
+    ///
     static void AddSymbol(const std::string &symbolName, void *symbolValue) {
       AddSymbol(symbolName.c_str(), symbolValue);
     }

diff --git a/lib/System/DynamicLibrary.cpp b/lib/System/DynamicLibrary.cpp
index b88d03f49439334a0503c56dc6170a3e6bf4a421..669422c8427cca85d0a8048b067ed17c109a1526 100644 (file)
--- a/lib/System/DynamicLibrary.cpp
+++ b/lib/System/DynamicLibrary.cpp
@@ -9,11 +9,13 @@
 //
 //  This header file implements the operating system DynamicLibrary concept.
 //
+// FIXME: This file leaks the ExplicitSymbols and OpenedHandles vector, and is
+// not thread safe!
+//
 //===----------------------------------------------------------------------===//
 
 #include "llvm/System/DynamicLibrary.h"
 #include "llvm/Support/ManagedStatic.h"
-#include "llvm/System/RWMutex.h"
 #include "llvm/Config/config.h"
 #include <cstdio>
 #include <cstring>
@@ -21,13 +23,13 @@
 #include <vector>
 
 // Collection of symbol name/value pairs to be searched prior to any libraries.
-static std::map<std::string, void*> symbols;
-static llvm::sys::SmartRWMutex<true> SymbolsLock;
+static std::map<std::string, void*> *ExplicitSymbols = 0;
 
 void llvm::sys::DynamicLibrary::AddSymbol(const char* symbolName,
                                           void *symbolValue) {
-  llvm::sys::SmartScopedWriter<true> Writer(&SymbolsLock);
-  symbols[symbolName] = symbolValue;
+  if (ExplicitSymbols == 0)
+    ExplicitSymbols = new std::map<std::string, void*>();
+  (*ExplicitSymbols)[symbolName] = symbolValue;
 }
 
 #ifdef LLVM_ON_WIN32
@@ -37,7 +39,6 @@ void llvm::sys::DynamicLibrary::AddSymbol(const char* symbolName,
 #else
 
 #include <dlfcn.h>
-#include <cassert>
 using namespace llvm;
 using namespace llvm::sys;
 
@@ -46,44 +47,44 @@ using namespace llvm::sys;
 //===          independent code.
 //===----------------------------------------------------------------------===//
 
-static std::vector<void *> OpenedHandles;
+static std::vector<void *> *OpenedHandles = 0;
 
 
 bool DynamicLibrary::LoadLibraryPermanently(const char *Filename,
                                             std::string *ErrMsg) {
-  SmartScopedWriter<true> Writer(&SymbolsLock);                                              
   void *H = dlopen(Filename, RTLD_LAZY|RTLD_GLOBAL);
   if (H == 0) {
-    if (ErrMsg)
-      *ErrMsg = dlerror();
+    if (ErrMsg) *ErrMsg = dlerror();
     return true;
   }
-  OpenedHandles.push_back(H);
+  if (OpenedHandles == 0)
+    OpenedHandles = new std::vector<void *>();
+  OpenedHandles->push_back(H);
   return false;
 }
 
 void* DynamicLibrary::SearchForAddressOfSymbol(const char* symbolName) {
   // First check symbols added via AddSymbol().
-  SymbolsLock.reader_acquire();
-  std::map<std::string, void *>::iterator I = symbols.find(symbolName);
-  std::map<std::string, void *>::iterator E = symbols.end();
-  SymbolsLock.reader_release();
+  if (ExplicitSymbols) {
+    std::map<std::string, void *>::iterator I =
+      ExplicitSymbols->find(symbolName);
+    std::map<std::string, void *>::iterator E = ExplicitSymbols->end();
   
-  if (I != E)
-    return I->second;
+    if (I != E)
+      return I->second;
+  }
 
-  SymbolsLock.writer_acquire();
   // Now search the libraries.
-  for (std::vector<void *>::iterator I = OpenedHandles.begin(),
-       E = OpenedHandles.end(); I != E; ++I) {
-    //lt_ptr ptr = lt_dlsym(*I, symbolName);
-    void *ptr = dlsym(*I, symbolName);
-    if (ptr) {
-      SymbolsLock.writer_release();
-      return ptr;
+  if (OpenedHandles) {
+    for (std::vector<void *>::iterator I = OpenedHandles->begin(),
+         E = OpenedHandles->end(); I != E; ++I) {
+      //lt_ptr ptr = lt_dlsym(*I, symbolName);
+      void *ptr = dlsym(*I, symbolName);
+      if (ptr) {
+        return ptr;
+      }
     }
   }
-  SymbolsLock.writer_release();
 
 #define EXPLICIT_SYMBOL(SYM) \
    extern void *SYM; if (!strcmp(symbolName, #SYM)) return &SYM