<p dir="ltr">Using GetModuleHandleEx for kernel32 seems unnecessary, as nothing on Windows can't can't really run without it being loaded. Is there really a reason to do that? </p>
<div class="gmail_quote">On Oct 13, 2013 12:39 PM, "David Majnemer" <<a href="mailto:david.majnemer@gmail.com">david.majnemer@gmail.com</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Author: majnemer<br>
Date: Sun Oct 13 05:34:21 2013<br>
New Revision: 192550<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=192550&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=192550&view=rev</a><br>
Log:<br>
Windows: Use GetModuleHandleEx instead of LoadLibrary<br>
<br>
We were using an anti-pattern of:<br>
 - LoadLibrary<br>
 - GetProcAddress<br>
 - FreeLibrary<br>
<br>
This is problematic because of several reasons:<br>
 - We are holding on to pointers into a library we just unloaded.<br>
 - Calling LoadLibrary results in an increase in the reference count of<br>
   the library in question and any libraries that it depends on and<br>
   so-on and so-forth.  This is none too quick.<br>
<br>
Instead, use GetModuleHandleEx with GET_MODULE_HANDLE_EX_FLAG_PIN.  This<br>
is done because because we didn't bring the reference for the library<br>
into existence and therefor shouldn't count on it being around later.<br>
<br>
Modified:<br>
    llvm/trunk/lib/Support/Windows/RWMutex.inc<br>
<br>
Modified: llvm/trunk/lib/Support/Windows/RWMutex.inc<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Windows/RWMutex.inc?rev=192550&r1=192549&r2=192550&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Windows/RWMutex.inc?rev=192550&r1=192549&r2=192550&view=diff</a><br>

==============================================================================<br>
--- llvm/trunk/lib/Support/Windows/RWMutex.inc (original)<br>
+++ llvm/trunk/lib/Support/Windows/RWMutex.inc Sun Oct 13 05:34:21 2013<br>
@@ -48,7 +48,8 @@ static bool loadSRW() {<br>
   if (!sChecked) {<br>
     sChecked = true;<br>
<br>
-    HMODULE hLib = ::LoadLibraryW(L"Kernel32.dll");<br>
+    HMODULE hLib;<br>
+    ::GetModuleHandleExW(GET_MODULE_HANDLE_EX_FLAG_PIN, L"Kernel32.dll", &hLib);<br>
     if (hLib) {<br>
       fpInitializeSRWLock =<br>
         (VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,<br>
@@ -65,7 +66,6 @@ static bool loadSRW() {<br>
       fpReleaseSRWLockShared =<br>
         (VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,<br>
                                                "ReleaseSRWLockShared");<br>
-      ::FreeLibrary(hLib);<br>
<br>
       if (fpInitializeSRWLock != NULL) {<br>
         sHasSRW = true;<br>
<br>
<br>
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</blockquote></div>