Revert GCStrategy ownership changes

This change reverts the interesting parts of 226311 (and 227046).  This change introduced two problems, and I've been convinced that an alternate approach is preferrable anyways.

The bugs were:
- Registery appears to require all users be within the same linkage unit.  After this change, asking for "statepoint-example" in Transform/ would sometimes get you nullptr, whereas asking the same question in CodeGen would return the right GCStrategy.  The correct long term fix is to get rid of the utter hack which is Registry, but I don't have time for that right now.  227046 appears to have been an attempt to fix this, but I don't believe it does so completely.
- GCMetadataPrinter::finishAssembly was being called more than once per GCStrategy.  Each Strategy was being added to the GCModuleInfo multiple times.

Once I get time again, I'm going to split GCModuleInfo into the gc.root specific part and a GCStrategy owning Analysis pass.  I'm probably also going to kill off the Registry.  Once that's done, I'll move the new GCStrategyAnalysis and all built in GCStrategies into Analysis.  (As original suggested by Chandler.)  This will accomplish my original goal of being able to access GCStrategy from Transform/  without adding all of the builtin GCs to IR/.  

llvm-svn: 227109

1 files changed, 23 insertions, 11 deletions

diff --git a/llvm/lib/CodeGen/GCMetadata.cpp b/llvm/lib/CodeGen/GCMetadata.cpp
index 7a61d61e7d0..ab8383a45c4 100644
--- a/llvm/lib/CodeGen/GCMetadata.cpp
+++ b/llvm/lib/CodeGen/GCMetadata.cpp
@@ -14,8 +14,8 @@
 #include "llvm/CodeGen/GCMetadata.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/GCStrategy.h"
 #include "llvm/IR/Function.h"
-#include "llvm/IR/GCStrategy.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/Debug.h"
@@ -66,15 +66,7 @@ GCFunctionInfo &GCModuleInfo::getFunctionInfo(const Function &F) {
   if (I != FInfoMap.end())
     return *I->second;
 
-  GCStrategy *S = F.getGCStrategy();
-  if (!S) {
-    std::string error = std::string("unsupported GC: ") + F.getGC();
-    report_fatal_error(error);
-  }
-  // Save the fact this strategy is associated with this module.  Note that
-  // these are non-owning references, the GCStrategy remains owned by the
-  // Context.
-  StrategyList.push_back(S);
+  GCStrategy *S = getGCStrategy(F.getGC());
   Functions.push_back(make_unique<GCFunctionInfo>(F, *S));
   GCFunctionInfo *GFI = Functions.back().get();
   FInfoMap[&F] = GFI;
@@ -84,7 +76,7 @@ GCFunctionInfo &GCModuleInfo::getFunctionInfo(const Function &F) {
 void GCModuleInfo::clear() {
   Functions.clear();
   FInfoMap.clear();
-  StrategyList.clear();
+  GCStrategyList.clear();
 }
 
 // -----------------------------------------------------------------------------
@@ -159,3 +151,23 @@ bool Printer::doFinalization(Module &M) {
   GMI->clear();
   return false;
 }
+
+
+GCStrategy *GCModuleInfo::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();
+    }
+  }
+
+  report_fatal_error(std::string("unsupported GC: ") + Name);
+}