From f25c19c6b57aec5670e87dc57840c6ac12252099 Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Fri, 9 Jun 2006 18:33:30 +0000
Subject: [PATCH] Make Loop able to verify that it is in LCSSA-form, and have
 the LCSSA pass assert on this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28738 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Analysis/LoopInfo.h |  5 ++++-
 lib/Analysis/LoopInfo.cpp        | 16 ++++++++++++++++
 lib/Transforms/Utils/LCSSA.cpp   |  4 +++-
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/include/llvm/Analysis/LoopInfo.h b/include/llvm/Analysis/LoopInfo.h
index 06b007cf3fc..d6d6edf5c08 100644
--- a/include/llvm/Analysis/LoopInfo.h
+++ b/include/llvm/Analysis/LoopInfo.h
@@ -98,7 +98,7 @@ public:
   /// isLoopInvariant - Return true if the specified value is loop invariant
   ///
   bool isLoopInvariant(Value *V) const;
-
+  
   //===--------------------------------------------------------------------===//
   // APIs for simple analysis of the loop.
   //
@@ -147,6 +147,9 @@ public:
   ///
   Value *getTripCount() const;
 
+  /// isLCSSAForm - Return true if the Loop is in LCSSA form
+  bool isLCSSAForm() const;
+
   //===--------------------------------------------------------------------===//
   // APIs for updating loop information after changing the CFG
   //
diff --git a/lib/Analysis/LoopInfo.cpp b/lib/Analysis/LoopInfo.cpp
index c7ce58ef915..eed2cd6c4ef 100644
--- a/lib/Analysis/LoopInfo.cpp
+++ b/lib/Analysis/LoopInfo.cpp
@@ -479,6 +479,22 @@ Value *Loop::getTripCount() const {
   return 0;
 }
 
+/// isLCSSAForm - Return true if the Loop is in LCSSA form
+bool Loop::isLCSSAForm() const {  
+  for (Loop::block_iterator BB = block_begin(), E = block_end();
+       BB != E; ++BB) {
+    for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end(); I != E; ++I)
+      for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E;
+           ++UI) {
+        BasicBlock *UserBB = cast<Instruction>(*UI)->getParent();
+        if (!isa<PHINode>(*UI) && !contains(UserBB)) {
+          return false;
+        }
+      }
+  }
+  
+  return true;
+}
 
 //===-------------------------------------------------------------------===//
 // APIs for updating loop information after changing the CFG
diff --git a/lib/Transforms/Utils/LCSSA.cpp b/lib/Transforms/Utils/LCSSA.cpp
index e1af50e7454..ecbf1804383 100644
--- a/lib/Transforms/Utils/LCSSA.cpp
+++ b/lib/Transforms/Utils/LCSSA.cpp
@@ -98,7 +98,7 @@ bool LCSSA::runOnFunction(Function &F) {
   for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) {
     changed |= visitSubloop(*I);
   }
-      
+  
   return changed;
 }
 
@@ -132,6 +132,8 @@ bool LCSSA::visitSubloop(Loop* L) {
     processInstruction(*I, exitBlocks);
   }
   
+  assert(L->isLCSSAForm());
+  
   return true;
 }