[PlaceSafepoints] Switch to being a FunctionPass

[reames]

Summary

The pass doesn't actually modify the module outside of the function being processed. The only confusing piece is that it both inserts calls and then inlines the resulting calls. Given that, it definitely invalidates module level analysis results, but many FunctionPasses do that.

include/llvm/Transforms/Scalar.h

 //===----------------------------------------------------------------------===//
 //
 // PlaceSafepoints - Rewrite any IR calls to gc.statepoints and insert any
 // safepoint polls (method entry, backedge) that might be required.  This pass
 // does not generate explicit relocation sequences - that's handled by
 // RewriteStatepointsForGC which can be run at an arbitrary point in the pass
 // order following this pass.
 //
-ModulePass *createPlaceSafepointsPass();
+FunctionPass *createPlaceSafepointsPass();
 
 //===----------------------------------------------------------------------===//
 //
 // RewriteStatepointsForGC - Rewrite any gc.statepoints which do not yet have
 // explicit relocations to include explicit relocations.
 //
 FunctionPass *createRewriteStatepointsForGCPass();
 

lib/Transforms/Scalar/PlaceSafepoints.cpp

 };
 }
 
 static cl::opt<bool> NoEntry("spp-no-entry", cl::Hidden, cl::init(false));
 static cl::opt<bool> NoCall("spp-no-call", cl::Hidden, cl::init(false));
 static cl::opt<bool> NoBackedge("spp-no-backedge", cl::Hidden, cl::init(false));
 
 namespace {
-struct PlaceSafepoints : public ModulePass {
+struct PlaceSafepoints : public FunctionPass {
   static char ID; // Pass identification, replacement for typeid
 
-  PlaceSafepoints() : ModulePass(ID) {
+  PlaceSafepoints() : FunctionPass(ID) {
     initializePlaceSafepointsPass(*PassRegistry::getPassRegistry());
   }
-  bool runOnModule(Module &M) override {
-    bool modified = false;
-    for (Function &F : M) {
-      modified |= runOnFunction(F);
-    }
-    return modified;
-  }
-  bool runOnFunction(Function &F);
+  bool runOnFunction(Function &F) override;
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     // We modify the graph wholesale (inlining, block insertion, etc).  We
     // preserve nothing at the moment.  We could potentially preserve dom tree
     // if that was worth doing
   }
 };
 }
for (size_t i = 0; i < ParsePointNeeded.size(); i++) {
     CS.getInstruction()->eraseFromParent();
   }
   return modified;
 }
 
 char PlaceBackedgeSafepointsImpl::ID = 0;
 char PlaceSafepoints::ID = 0;
 
-ModulePass *llvm::createPlaceSafepointsPass() { return new PlaceSafepoints(); }
+FunctionPass *llvm::createPlaceSafepointsPass() {
+  return new PlaceSafepoints();
+}
 
 INITIALIZE_PASS_BEGIN(PlaceBackedgeSafepointsImpl,
                       "place-backedge-safepoints-impl",
                       "Place Backedge Safepoints", false, false)
 INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
 INITIALIZE_PASS_END(PlaceBackedgeSafepointsImpl,