From b4559a2179bf64fa38b2cccf91b067cc6fcc8e9d Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Fri, 13 Jul 2007 23:57:11 +0000
Subject: [PATCH] Make LCSSA a loop pass.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@39844 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Transforms/Scalar.h |  2 +-
 lib/Transforms/Utils/LCSSA.cpp   | 32 +++++++++++---------------------
 2 files changed, 12 insertions(+), 22 deletions(-)

diff --git a/include/llvm/Transforms/Scalar.h b/include/llvm/Transforms/Scalar.h
index ff12dc9ab7b..4fea3f73be1 100644
--- a/include/llvm/Transforms/Scalar.h
+++ b/include/llvm/Transforms/Scalar.h
@@ -306,7 +306,7 @@ FunctionPass *createBlockPlacementPass();
 // LCSSA - This pass inserts phi nodes at loop boundaries to simplify other loop
 // optimizations.
 //
-FunctionPass *createLCSSAPass();
+LoopPass *createLCSSAPass();
 extern const PassInfo *LCSSAID;
 
 //===----------------------------------------------------------------------===//
diff --git a/lib/Transforms/Utils/LCSSA.cpp b/lib/Transforms/Utils/LCSSA.cpp
index ed166644d7f..3f4bad5c513 100644
--- a/lib/Transforms/Utils/LCSSA.cpp
+++ b/lib/Transforms/Utils/LCSSA.cpp
@@ -36,7 +36,8 @@
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/Dominators.h"
-#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/ScalarEvolution.h"
 #include "llvm/Support/CFG.h"
 #include "llvm/Support/Compiler.h"
 #include <algorithm>
@@ -46,17 +47,17 @@ using namespace llvm;
 STATISTIC(NumLCSSA, "Number of live out of a loop variables");
 
 namespace {
-  struct VISIBILITY_HIDDEN LCSSA : public FunctionPass {
+  struct VISIBILITY_HIDDEN LCSSA : public LoopPass {
     static char ID; // Pass identification, replacement for typeid
-    LCSSA() : FunctionPass((intptr_t)&ID) {}
+    LCSSA() : LoopPass((intptr_t)&ID) {}
 
     // Cached analysis information for the current function.
     LoopInfo *LI;
     DominatorTree *DT;
     std::vector<BasicBlock*> LoopBlocks;
     
-    virtual bool runOnFunction(Function &F);
-    bool visitSubloop(Loop* L);
+    virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
+
     void ProcessInstruction(Instruction* Instr,
                             const std::vector<BasicBlock*>& exitBlocks);
     
@@ -69,7 +70,9 @@ namespace {
       AU.addRequiredID(LoopSimplifyID);
       AU.addPreservedID(LoopSimplifyID);
       AU.addRequired<LoopInfo>();
+      AU.addPreserved<LoopInfo>();
       AU.addRequired<DominatorTree>();
+      AU.addPreserved<ScalarEvolution>();
     }
   private:
     void getLoopValuesUsedOutsideLoop(Loop *L,
@@ -88,28 +91,15 @@ namespace {
   RegisterPass<LCSSA> X("lcssa", "Loop-Closed SSA Form Pass");
 }
 
-FunctionPass *llvm::createLCSSAPass() { return new LCSSA(); }
+LoopPass *llvm::createLCSSAPass() { return new LCSSA(); }
 const PassInfo *llvm::LCSSAID = X.getPassInfo();
 
 /// runOnFunction - Process all loops in the function, inner-most out.
-bool LCSSA::runOnFunction(Function &F) {
-  bool changed = false;
+bool LCSSA::runOnLoop(Loop *L, LPPassManager &LPM) {
   
-  LI = &getAnalysis<LoopInfo>();
+  LI = &LPM.getAnalysis<LoopInfo>();
   DT = &getAnalysis<DominatorTree>();
     
-  for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
-    changed |= visitSubloop(*I);
-      
-  return changed;
-}
-
-/// visitSubloop - Recursively process all subloops, and then process the given
-/// loop if it has live-out values.
-bool LCSSA::visitSubloop(Loop* L) {
-  for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
-    visitSubloop(*I);
-    
   // Speed up queries by creating a sorted list of blocks
   LoopBlocks.clear();
   LoopBlocks.insert(LoopBlocks.end(), L->block_begin(), L->block_end());