From aafb1c16b4de9aaa5e33c035dabcacdc3b66396f Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Fri, 28 May 2004 23:54:07 +0000
Subject: [PATCH] Thoroughly rehack the dynamic linking mechanisms on Win32. 
 The Win32 dynamic linker does not automatically search libraries when looking
 up symbols with GetProcAddress.  Because of this we have to emulate it.  The
 only detail is that there doesn't seem to be a way to enumerate the libraries
 loaded, so we have a gross hack (tm).

This make the JIT functional on win32 under cygwin.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13887 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Support/DynamicLinker.cpp | 57 +++++++++++++++++++++++++----------
 1 file changed, 41 insertions(+), 16 deletions(-)

diff --git a/lib/Support/DynamicLinker.cpp b/lib/Support/DynamicLinker.cpp
index cf00bea2db8..4ac58c1bbc0 100644
--- a/lib/Support/DynamicLinker.cpp
+++ b/lib/Support/DynamicLinker.cpp
@@ -12,8 +12,7 @@
 // provides it.
 //
 // Possible future extensions include support for the HPUX shl_load()
-// interface, the Mac OS X NSLinkModule() interface, and the Windows
-// LoadLibrary() interface.
+// interface, and the Mac OS X NSLinkModule() interface.
 //
 // Note that we assume that if dlopen() is available, then dlsym() is too.
 //
@@ -23,18 +22,36 @@
 #include "Config/dlfcn.h"
 #include "Config/windows.h"
 #include <cassert>
+#include <vector>
 using namespace llvm;
 
-bool llvm::LinkDynamicObject (const char *filename, std::string *ErrorMessage) {
-#if defined (HAVE_DLOPEN)
-  if (dlopen (filename, RTLD_NOW | RTLD_GLOBAL) == 0) {
-    if (ErrorMessage) *ErrorMessage = dlerror ();
-    return true;
+#if defined(HAVE_WINDOWS_H)
+// getLoadedLibs - Keep track of the shared objects that are loaded into the
+// process address space, as the windows GetProcAddress function does not
+// automatically search an entire address space, it only searches a specific
+// object.
+static std::vector<HMODULE> &getLoadedLibHandles() {
+  static std::vector<HMODULE> *LoadedLibHandles = 0;
+  if (LoadedLibHandles == 0) {
+    LoadedLibHandles = new std::vector<HMODULE>();
+    if (HMODULE H = GetModuleHandle(NULL))                // JIT symbols
+      LoadedLibHandles->push_back(H);
+    if (HMODULE MH = GetModuleHandle("cygwin1.dll"))      // Cygwin symbols OR
+      LoadedLibHandles->push_back(MH);
+    else if (HMODULE MH = GetModuleHandle("msvcr80.dll")) // VC++ symbols
+      LoadedLibHandles->push_back(MH);
   }
-  return false;
-#elif defined(HAVE_WINDOWS_H)
-  if (LoadLibrary(filename))
+  return *LoadedLibHandles;
+}
+#endif
+
+bool llvm::LinkDynamicObject(const char *filename, std::string *ErrorMessage) {
+#if defined(HAVE_WINDOWS_H)
+  if (HMODULE Handle = LoadLibrary(filename)) {
+    // Allow GetProcAddress in this module
+    getLoadedLibHandles().push_back(Handle);
     return false;
+  }
   if (ErrorMessage) {
     char Buffer[100];
     // FIXME: This should use FormatMessage
@@ -42,23 +59,31 @@ bool llvm::LinkDynamicObject (const char *filename, std::string *ErrorMessage) {
     *ErrorMessage = Buffer;
   }
   return true;
+#elif defined (HAVE_DLOPEN)
+  if (dlopen (filename, RTLD_NOW | RTLD_GLOBAL) == 0) {
+    if (ErrorMessage) *ErrorMessage = dlerror ();
+    return true;
+  }
+  return false;
 #else
   assert (0 && "Dynamic object linking not implemented for this platform");
 #endif
 }
 
-void *llvm::GetAddressOfSymbol (const char *symbolName) {
-#if defined (HAVE_DLOPEN)
+void *llvm::GetAddressOfSymbol(const char *symbolName) {
+#if defined(HAVE_WINDOWS_H)
+  std::vector<HMODULE> &LH = getLoadedLibHandles();
+  for (unsigned i = 0, e = LH.size(); i != e; ++i)
+    if (void *Val = (void*)GetProcAddress(LH[i], symbolName))
+      return Val;
+  return 0;
+#elif defined(HAVE_DLOPEN)
 #  ifdef RTLD_DEFAULT
     return dlsym (RTLD_DEFAULT, symbolName);
 #  else
     static void* CurHandle = dlopen(0, RTLD_LAZY);
     return dlsym(CurHandle, symbolName);
 #  endif
-#elif defined(HAVE_WINDOWS_H)
-  static HMODULE ModHandle = NULL;
-  if (ModHandle == 0) ModHandle = GetModuleHandle(NULL);
-  return (void*)GetProcAddress(ModHandle, symbolName);
 #else
   assert (0 && "Dynamic symbol lookup not implemented for this platform");
 #endif