Lookup Windows functions in process.

Signed-off-by: Vassil Vassilev <vvasilev@cern.ch>

include/cling/Utils/Platform.h

@@ -96,6 +96,12 @@ inline namespace windows {
   ///
   bool IsDLL(const std::string& Path);
 
+  ///\brief Look for given symbol in all modules loaded by the current process
+  ///
+  /// \returns The adress of the symbol or null if not found
+  ///
+  const void* LookupSymbol(const std::string& Name);
+
   /// \brief Read registry string.
   /// This also supports a means to look for high-versioned keys by use
   /// of a $VERSION placeholder in the key path.

lib/Interpreter/IncrementalJIT.cpp

@@ -10,6 +10,7 @@
 #include "IncrementalJIT.h"
 
 #include "IncrementalExecutor.h"
+#include "cling/Utils/Platform.h"
 
 #include "llvm/ExecutionEngine/Orc/LambdaResolver.h"
 #include "llvm/Support/DynamicLibrary.h"
@@ -217,13 +218,20 @@ IncrementalJIT::getSymbolAddressWithoutMangling(llvm::StringRef Name,
   if (auto Sym = getInjectedSymbols(Name))
     return Sym;
 
+  // Avoid constructing std::string from llvm::StringRef more than once
+  const std::string SymName = Name;
   if (AlsoInProcess) {
-    if (RuntimeDyld::SymbolInfo SymInfo = m_ExeMM->findSymbol(Name))
+    if (RuntimeDyld::SymbolInfo SymInfo = m_ExeMM->findSymbol(SymName))
       return llvm::orc::JITSymbol(SymInfo.getAddress(),
                                   llvm::JITSymbolFlags::Exported);
+#ifdef LLVM_ON_WIN32
+    if (const void* Sym = platform::LookupSymbol(SymName))
+      return llvm::orc::JITSymbol(llvm::orc::TargetAddress(Sym),
+                                  llvm::JITSymbolFlags::Exported);
+#endif
   }
 
-  if (auto Sym = m_LazyEmitLayer.findSymbol(Name, false))
+  if (auto Sym = m_LazyEmitLayer.findSymbol(SymName, false))
     return Sym;
 
   return llvm::orc::JITSymbol(nullptr);

lib/Utils/PlatformWin.cpp

@@ -86,6 +86,49 @@ bool ReportLastError(const char* Prefix) {
   return false;
 }
 
+const void* LookupSymbol(const std::string& Name) {
+ #ifdef _WIN64
+  const DWORD Flags = LIST_MODULES_64BIT;
+ #else
+  const DWORD Flags = LIST_MODULES_32BIT;
+ #endif
+
+  DWORD Bytes;
+  const std::string CStr(Name);
+  std::string ErrStr;
+  llvm::SmallVector<HMODULE, 128> Modules;
+  Modules.resize(Modules.capacity());
+  if (::EnumProcessModulesEx(::GetCurrentProcess(), &Modules[0],
+                           Modules.capacity_in_bytes(), &Bytes, Flags) != 0) {
+    // Search the modules we got
+    const DWORD NumNeeded = Bytes/sizeof(HMODULE);
+    const DWORD NumFirst = Modules.size();
+    if (NumNeeded < NumFirst)
+      Modules.resize(NumNeeded);
+
+    // In reverse so user loaded modules are searched first
+    for (auto It = Modules.rbegin(), End = Modules.rend(); It < End; ++It) {
+      if (const void* Addr = ::GetProcAddress(*It, CStr.c_str()))
+            return Addr;
+    }
+    if (NumNeeded > NumFirst) {
+      // The number of modules was too small to get them all, so call again
+      Modules.resize(NumNeeded);
+      if (::EnumProcessModulesEx(::GetCurrentProcess(), &Modules[0],
+                               Modules.capacity_in_bytes(), &Bytes, Flags) != 0) {
+        for (DWORD i = NumNeeded-1; i > NumFirst; --i) {
+          if (const void* Addr = ::GetProcAddress(Modules[i], CStr.c_str()))
+            return Addr;
+        }
+      } else
+        ReportLastError("EnumProcessModulesEx");
+    }
+  } else
+    ReportLastError("EnumProcessModulesEx");
+
+  return nullptr;
+}
+
 namespace {
 
 // Taken from clang/lib/Driver/MSVCToolChain.cpp