5 files changed, 65 insertions, 0 deletions

diff --git a/llvm/lib/IR/CMakeLists.txt b/llvm/lib/IR/CMakeLists.txt
index 1a210e05827..621c7ca9224 100644
--- a/llvm/lib/IR/CMakeLists.txt
+++ b/llvm/lib/IR/CMakeLists.txt
@@ -17,6 +17,7 @@ add_llvm_library(LLVMCore
   Dominators.cpp
   Function.cpp
   GCOV.cpp
+  GCStrategy.cpp
   GVMaterializer.cpp
   Globals.cpp
   IRBuilder.cpp
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index 070513edef2..ddfbaf7a187 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -386,6 +386,12 @@ void Function::clearGC() {
   }
 }
 
+GCStrategy *Function::getGCStrategy() const {
+  // Lookup the GCStrategy (which is owned by the Context), given the name of
+  // the GC in question.
+  return getContext().pImpl->getGCStrategy(getGC());
+}
+
 /// copyAttributesFrom - copy all additional attributes (those not needed to
 /// create a Function) from the Function Src to this one.
 void Function::copyAttributesFrom(const GlobalValue *Src) {
diff --git a/llvm/lib/IR/GCStrategy.cpp b/llvm/lib/IR/GCStrategy.cpp
new file mode 100644
index 00000000000..18723a0f514
--- /dev/null
+++ b/llvm/lib/IR/GCStrategy.cpp
@@ -0,0 +1,22 @@
+//===-- GCStrategy.cpp - Garbage Collector Description --------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the policy object GCStrategy which describes the
+// behavior of a given garbage collector.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/GCStrategy.h"
+
+using namespace llvm;
+
+GCStrategy::GCStrategy()
+    : UseStatepoints(false), NeededSafePoints(0), CustomReadBarriers(false),
+      CustomWriteBarriers(false), CustomRoots(false),
+      InitRoots(true), UsesMetadata(false) {}
diff --git a/llvm/lib/IR/LLVMContextImpl.cpp b/llvm/lib/IR/LLVMContextImpl.cpp
index 01a0e6c98a6..01a786dbfda 100644
--- a/llvm/lib/IR/LLVMContextImpl.cpp
+++ b/llvm/lib/IR/LLVMContextImpl.cpp
@@ -15,6 +15,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/DiagnosticInfo.h"
+#include "llvm/IR/GCStrategy.h"
 #include "llvm/IR/Module.h"
 #include <algorithm>
 using namespace llvm;
@@ -182,3 +183,26 @@ void InsertValueConstantExpr::anchor() { }
 void GetElementPtrConstantExpr::anchor() { }
 
 void CompareConstantExpr::anchor() { }
+
+GCStrategy *LLVMContextImpl::getGCStrategy(const StringRef Name) {
+  // TODO: Arguably, just doing a linear search would be faster for small N
+  auto NMI = GCStrategyMap.find(Name);
+  if (NMI != GCStrategyMap.end())
+    return NMI->getValue();
+  
+  for (auto& Entry : GCRegistry::entries()) {
+    if (Name == Entry.getName()) {
+      std::unique_ptr<GCStrategy> S = Entry.instantiate();
+      S->Name = Name;
+      GCStrategyMap[Name] = S.get();
+      GCStrategyList.push_back(std::move(S));
+      return GCStrategyList.back().get();
+    }
+  }
+
+  // No GCStrategy found for that name, error reporting is the job of our
+  // callers. 
+  return nullptr;
+}
+
+
diff --git a/llvm/lib/IR/LLVMContextImpl.h b/llvm/lib/IR/LLVMContextImpl.h
index 6ebc567f808..45f86093f52 100644
--- a/llvm/lib/IR/LLVMContextImpl.h
+++ b/llvm/lib/IR/LLVMContextImpl.h
@@ -41,6 +41,7 @@ class ConstantFP;
 class DiagnosticInfoOptimizationRemark;
 class DiagnosticInfoOptimizationRemarkMissed;
 class DiagnosticInfoOptimizationRemarkAnalysis;
+class GCStrategy;
 class LLVMContext;
 class Type;
 class Value;
@@ -389,6 +390,17 @@ public:
 
   int getOrAddScopeRecordIdxEntry(MDNode *N, int ExistingIdx);
   int getOrAddScopeInlinedAtIdxEntry(MDNode *Scope, MDNode *IA,int ExistingIdx);
+
+  /// An owning list of all GCStrategies which have been created
+  SmallVector<std::unique_ptr<GCStrategy>, 1> GCStrategyList;
+  /// A helper map to speedup lookups into the above list
+  StringMap<GCStrategy*> GCStrategyMap;
+
+  /// Lookup the GCStrategy object associated with the given gc name.  If one
+  /// can't be found, returns nullptr.  The lifetime of the returned objects
+  /// is dictated by the lifetime of the associated context.  No caller should
+  /// attempt to delete the returned objects.
+  GCStrategy *getGCStrategy(const StringRef Name);
   
   LLVMContextImpl(LLVMContext &C);
   ~LLVMContextImpl();