Add a separate llvm.global_ctors entry for linkonce_odr data initializers
Summary:
These typically come from static data members of class template
specializations. This accomplishes two things:
1. May expose GlobalOpt optimizations for Itanium C++ ABI code.
2. Works toward fixing double initialization in the Microsoft C++ ABI.
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1475
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@189051 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGDeclCXX.cpp b/lib/CodeGen/CGDeclCXX.cpp
index d61755c..ff06448 100644
--- a/lib/CodeGen/CGDeclCXX.cpp
+++ b/lib/CodeGen/CGDeclCXX.cpp
@@ -278,6 +278,19 @@
OrderGlobalInits Key(order, PrioritizedCXXGlobalInits.size());
PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn));
DelayedCXXInitPosition.erase(D);
+ } else if (D->getInstantiatedFromStaticDataMember()) {
+ // C++ [basic.start.init]p2:
+ // Defnitions of explicitly specialized class template static data members
+ // have ordered initialization. Other class template static data members
+ // (i.e., implicitly or explicitly instantiated specializations) have
+ // unordered initialization.
+ //
+ // As a consequence, we can put them into their own llvm.global_ctors entry.
+ // This should allow GlobalOpt to fire more often, and allow us to implement
+ // the Microsoft C++ ABI, which uses COMDAT elimination to avoid double
+ // initializaiton.
+ AddGlobalCtor(Fn);
+ DelayedCXXInitPosition.erase(D);
} else {
llvm::DenseMap<const Decl *, unsigned>::iterator I =
DelayedCXXInitPosition.find(D);