[llvm-commits] [llvm] r52243 - in /llvm/trunk: lib/Transforms/Scalar/TailDuplication.cpp test/Transforms/TailDup/2008-06-11-AvoidDupLoopHeader.ll

[Evan Cheng]

Author: evancheng
Date: Thu Jun 12 15:55:39 2008
New Revision: 52243

URL: http://llvm.org/viewvc/llvm-project?rev=52243&view=rev
Log:
Revert 52223.

Modified:
    llvm/trunk/lib/Transforms/Scalar/TailDuplication.cpp
    llvm/trunk/test/Transforms/TailDup/2008-06-11-AvoidDupLoopHeader.ll

Modified: llvm/trunk/lib/Transforms/Scalar/TailDuplication.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/TailDuplication.cpp?rev=52243&r1=52242&r2=52243&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/TailDuplication.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/TailDuplication.cpp Thu Jun 12 15:55:39 2008
@@ -33,7 +33,6 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/Analysis/LoopInfo.h"
 #include <map>
 using namespace llvm;
 
@@ -51,12 +50,10 @@
     static char ID; // Pass identification, replacement for typeid
     TailDup() : FunctionPass((intptr_t)&ID) {}
 
-    virtual void getAnalysisUsage(AnalysisUsage &AU) const;
   private:
     inline bool shouldEliminateUnconditionalBranch(TerminatorInst *, unsigned);
     inline void eliminateUnconditionalBranch(BranchInst *BI);
     SmallPtrSet<BasicBlock*, 4> CycleDetector;
-    LoopInfo *LI;  // The current loop information
   };
 }
 
@@ -72,9 +69,6 @@
 /// a place it already pointed to earlier; see PR 2323.
 bool TailDup::runOnFunction(Function &F) {
   bool Changed = false;
-
-  LI = &getAnalysis<LoopInfo>();
-
   CycleDetector.clear();
   for (Function::iterator I = F.begin(), E = F.end(); I != E; ) {
     if (shouldEliminateUnconditionalBranch(I->getTerminator(),
@@ -89,10 +83,6 @@
   return Changed;
 }
 
-void TailDup::getAnalysisUsage(AnalysisUsage &AU) const {
-  AU.addRequired<LoopInfo>();
-}
-
 /// shouldEliminateUnconditionalBranch - Return true if this branch looks
 /// attractive to eliminate.  We eliminate the branch if the destination basic
 /// block has <= 5 instructions in it, not counting PHI nodes.  In practice,
@@ -196,14 +186,6 @@
   if (!CycleDetector.insert(Dest))
     return false;
 
-  // Avoid non-natural loops:
-  // If a loop header is duplicated, the former natural loop will contain two
-  // paths into the loop --> the loop it not natural anymore. We want to avoid
-  // this, because other optimizaions may fail to improve the loop because of 
-  // this.
-  if (LI->isLoopHeader(Dest))
-    return false;
-
   return true;
 }
 

Modified: llvm/trunk/test/Transforms/TailDup/2008-06-11-AvoidDupLoopHeader.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/TailDup/2008-06-11-AvoidDupLoopHeader.ll?rev=52243&r1=52242&r2=52243&view=diff

==============================================================================
--- llvm/trunk/test/Transforms/TailDup/2008-06-11-AvoidDupLoopHeader.ll (original)
+++ llvm/trunk/test/Transforms/TailDup/2008-06-11-AvoidDupLoopHeader.ll Thu Jun 12 15:55:39 2008
@@ -1,5 +1,5 @@
-; RUN: llvm-as < %s | opt -tailduplicate -taildup-threshold=3 -stats -disable-output |& \
-; RUN:   not grep tailduplicate
+; RUN: llvm-as < %s | opt -tailduplicate -taildup-threshold=3 -stats -disable-output | not grep tailduplicate
+; XFAIL: *
 
 define i32 @foo(i32 %l) nounwind  {
 entry: