From a549b51a32a6f5c522e9b0e81526112e742fe954 Mon Sep 17 00:00:00 2001
From: NAKAMURA Takumi <geek4civic@gmail.com>
Date: Fri, 5 Oct 2012 14:10:23 +0000
Subject: [PATCH] lli: [MCJIT] Suppress "__main" for cygming in
 LLIMCJITMemoryManager::getPointerToNamedFunction(), like legacy
 JITMemoryManager's.

CRT's __main (aka premain) invokes global ctors on cygming. See also PR3897.

llvm-svn: 165312
---
 llvm/tools/lli/lli.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/llvm/tools/lli/lli.cpp b/llvm/tools/lli/lli.cpp
index c5645ec6015f..57a31f21b89d 100644
--- a/llvm/tools/lli/lli.cpp
+++ b/llvm/tools/lli/lli.cpp
@@ -338,6 +338,10 @@ void LLIMCJITMemoryManager::invalidateInstructionCache() {
                                             AllocatedCodeMem[i].size());
 }
 
+static int jit_noop() {
+  return 0;
+}
+
 void *LLIMCJITMemoryManager::getPointerToNamedFunction(const std::string &Name,
                                                        bool AbortOnFailure) {
 #if defined(__linux__)
@@ -360,6 +364,14 @@ void *LLIMCJITMemoryManager::getPointerToNamedFunction(const std::string &Name,
   if (Name == "mknod") return (void*)(intptr_t)&mknod;
 #endif // __linux__
 
+  // We should not invoke parent's ctors/dtors from generated main()!
+  // On Mingw and Cygwin, the symbol __main is resolved to
+  // callee's(eg. tools/lli) one, to invoke wrong duplicated ctors
+  // (and register wrong callee's dtors with atexit(3)).
+  // We expect ExecutionEngine::runStaticConstructorsDestructors()
+  // is called before ExecutionEngine::runFunctionAsMain() is called.
+  if (Name == "__main") return (void*)(intptr_t)&jit_noop;
+
   const char *NameStr = Name.c_str();
   void *Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(NameStr);
   if (Ptr) return Ptr;