[PM] Port LoopInfo to the new pass manager, adding both a LoopAnalysis

pass and a LoopPrinterPass with the expected associated wiring.

I've added a RUN line to the only test case (!!!) we have that actually
prints loops. Everything seems to be working.

This is somewhat exciting as this is the first analysis using another
analysis to go in for the new pass manager. =D I also believe it is the
last analysis necessary for porting instcombine, but of course I may yet
discover more.

llvm-svn: 226560

1 files changed, 21 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/LoopInfo.cpp b/llvm/lib/Analysis/LoopInfo.cpp
index 5fde485beca..95f6eb0af0f 100644
--- a/llvm/lib/Analysis/LoopInfo.cpp
+++ b/llvm/lib/Analysis/LoopInfo.cpp
@@ -26,6 +26,7 @@
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Metadata.h"
+#include "llvm/IR/PassManager.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include <algorithm>
@@ -667,6 +668,26 @@ void LoopInfo::updateUnloop(Loop *Unloop) {
   }
 }
 
+char LoopAnalysis::PassID;
+
+LoopInfo LoopAnalysis::run(Function &F, AnalysisManager<Function> *AM) {
+  // FIXME: Currently we create a LoopInfo from scratch for every function.
+  // This may prove to be too wasteful due to deallocating and re-allocating
+  // memory each time for the underlying map and vector datastructures. At some
+  // point it may prove worthwhile to use a freelist and recycle LoopInfo
+  // objects. I don't want to add that kind of complexity until the scope of
+  // the problem is better understood.
+  LoopInfo LI;
+  LI.Analyze(AM->getResult<DominatorTreeAnalysis>(F));
+  return std::move(LI);
+}
+
+PreservedAnalyses LoopPrinterPass::run(Function &F,
+                                       AnalysisManager<Function> *AM) {
+  AM->getResult<LoopAnalysis>(F).print(OS);
+  return PreservedAnalyses::all();
+}
+
 //===----------------------------------------------------------------------===//
 // LoopInfo implementation
 //