Revert "[SimlifyCFG] Prevent passes from destroying canonical loop structure, especially for nested loops"

This reverts commit r264596.

It does not compile.

llvm-svn: 264604

1 files changed, 2 insertions, 10 deletions

diff --git a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
index 72ce7693ec0..687d388701e 100644
--- a/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
+++ b/llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
@@ -28,7 +28,6 @@
 #include "llvm/Analysis/GlobalsModRef.h"
 #include "llvm/Analysis/AssumptionCache.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
-#include "llvm/Analysis/CFG.h"
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/CFG.h"
 #include "llvm/IR/Constants.h"
@@ -131,20 +130,13 @@ static bool iterativelySimplifyCFG(Function &F, const TargetTransformInfo &TTI,
                                    AssumptionCache *AC,
                                    unsigned BonusInstThreshold) {
   bool Changed = false;
-  bool LocalChange = true; 
-
-  SmallVector<std::pair<const BasicBlock *, const BasicBlock *>, 32> Edges;
-  FindFunctionBackedges(F, Edges);
-  SmallPtrSet<BasicBlock *, 16> LoopHeaders;
-  for (unsigned i = 0, e = Edges.size(); i != e; ++i)
-    LoopHeaders.insert(const_cast<BasicBlock *>(Edges[i].second));
-
+  bool LocalChange = true;
   while (LocalChange) {
     LocalChange = false;
 
     // Loop over all of the basic blocks and remove them if they are unneeded.
     for (Function::iterator BBIt = F.begin(); BBIt != F.end(); ) {
-      if (SimplifyCFG(&*BBIt++, TTI, BonusInstThreshold, AC, &LoopHeaders)) {
+      if (SimplifyCFG(&*BBIt++, TTI, BonusInstThreshold, AC)) {
         LocalChange = true;
         ++NumSimpl;
       }