Refactor DynamicLibrary so searching for a symbol will have a defined order and

libraries are properly unloaded when llvm_shutdown is called.

Summary:
This was mostly affecting usage of the JIT, where storing the library handles in
a set made iteration unordered/undefined. This lead to disagreement between the
JIT and native code as to what the address and implementation of particularly on
Windows with stdlib functions:

JIT: putenv_s("TEST", "VALUE") // called msvcrt.dll, putenv_s
JIT: getenv("TEST") -> "VALUE" // called msvcrt.dll, getenv
Native: getenv("TEST") -> NULL // called ucrt.dll, getenv

Also fixed is the issue of DynamicLibrary::getPermanentLibrary(0,0) on Windows
not giving priority to the process' symbols as it did on Unix.

Reviewers: chapuni, v.g.vassilev, lhames

Reviewed By: lhames

Subscribers: danalbert, srhines, mgorny, vsk, llvm-commits

Differential Revision: https://reviews.llvm.org/D30107

llvm-svn: 301562

1 files changed, 5 insertions, 2 deletions

diff --git a/llvm/include/llvm/Support/DynamicLibrary.h b/llvm/include/llvm/Support/DynamicLibrary.h
index aa9bb8938ad..a8874a10d46 100644
--- a/llvm/include/llvm/Support/DynamicLibrary.h
+++ b/llvm/include/llvm/Support/DynamicLibrary.h
@@ -58,7 +58,7 @@ namespace sys {
     void *getAddressOfSymbol(const char *symbolName);
 
     /// This function permanently loads the dynamic library at the given path.
-    /// The library will only be unloaded when the program terminates.
+    /// The library will only be unloaded when llvm_shutdown() is called.
     /// This returns a valid DynamicLibrary instance on success and an invalid
     /// instance on failure (see isValid()). \p *errMsg will only be modified
     /// if the library fails to load.
@@ -71,7 +71,8 @@ namespace sys {
     /// Registers an externally loaded library. The library will be unloaded
     /// when the program terminates.
     ///
-    /// It is safe to call this function multiple times for the same library.
+    /// It is safe to call this function multiple times for the same library,
+    /// though ownership is only taken if there was no error.
     ///
     /// \returns An empty \p DynamicLibrary if the library was already loaded.
     static DynamicLibrary addPermanentLibrary(void *handle,
@@ -106,6 +107,8 @@ namespace sys {
     /// libraries.
     /// @brief Add searchable symbol/value pair.
     static void AddSymbol(StringRef symbolName, void *symbolValue);
+
+    class HandleSet;
   };
 
 } // End sys namespace