From 03a11340ff6dec73ab8cb09261ae374ae4003417 Mon Sep 17 00:00:00 2001
From: Misha Brukman <brukman+llvm@gmail.com>
Date: Sat, 28 Feb 2004 03:33:01 +0000
Subject: [PATCH] A pass that uses the generic CodeExtractor to rip out *every*
 loop in every function, as long as the loop isn't the only one in that
 function. This should help debugging passes easier with BugPoint.

llvm-svn: 11936
---
 llvm/lib/Transforms/Utils/LoopExtractor.cpp | 69 +++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 llvm/lib/Transforms/Utils/LoopExtractor.cpp

diff --git a/llvm/lib/Transforms/Utils/LoopExtractor.cpp b/llvm/lib/Transforms/Utils/LoopExtractor.cpp
new file mode 100644
index 000000000000..aae7ccbe4804
--- /dev/null
+++ b/llvm/lib/Transforms/Utils/LoopExtractor.cpp
@@ -0,0 +1,69 @@
+//===- LoopExtractor.cpp - Extract each loop into a new function ----------===//
+//
+// A pass wrapper around the ExtractLoop() scalar transformation to extract each
+// top-level loop into its own new function. If the loop is the ONLY loop in a
+// given function, it is not touched.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/FunctionUtils.h"
+#include <vector>
+using namespace llvm;
+
+namespace {
+
+// FIXME: PassManager should allow Module passes to require FunctionPasses
+struct LoopExtraction : public FunctionPass {
+
+public:
+  LoopExtractor() {}
+  virtual bool run(Module &M);
+  virtual bool runOnFunction(Function &F);
+
+  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+    AU.addRequired<LoopInfo>();
+  }
+
+};
+
+RegisterOpt<LoopExtractor> 
+X("loop-extract", "Extract loops into new functions");
+
+bool LoopExtractor::run(Module &M) {
+  bool Changed = false;
+  for (Module::iterator i = M.begin(), e = M.end(); i != e; ++i)
+    Changed |= runOnFunction(*i);
+  return Changed;
+}
+
+bool LoopExtractor::runOnFunction(Function &F) {
+  std::cerr << F.getName() << "\n";
+
+  LoopInfo &LI = getAnalysis<LoopInfo>();
+
+  // We don't want to keep extracting the only loop of a function into a new one
+  if (LI.begin() == LI.end() || LI.begin() + 1 == LI.end())
+    return false;
+
+  bool Changed = false;
+
+  // Try to move each loop out of the code into separate function
+  for (LoopInfo::iterator i = LI.begin(), e = LI.end(); i != e; ++i)
+    Changed |= (ExtractLoop(*i) != 0);
+
+  return Changed;
+}
+
+
+
+} // End anonymous namespace 
+
+/// createLoopExtractorPass 
+///
+FunctionPass* llvm::createLoopExtractorPass() {
+  return new LoopExtractor;
+}