[llvm] r289548 - [ADCE] Add code to remove dead branches

David Callahan via llvm-commits llvm-commits at lists.llvm.org
Tue Dec 13 08:42:18 PST 2016


Author: david2050
Date: Tue Dec 13 10:42:18 2016
New Revision: 289548

URL: http://llvm.org/viewvc/llvm-project?rev=289548&view=rev
Log:
[ADCE] Add code to remove dead branches

Summary:
This is last in of a series of patches to evolve ADCE.cpp to support
removing of unnecessary control flow.

This patch adds the code to update the control and data flow graphs
to remove the dead control flow.

Also update unit tests to test the capability to remove dead,
may-be-infinite loop which is enabled by the switch
-adce-remove-loops.

Previous patches:

D23824 [ADCE] Add handling of PHI nodes when removing control flow
D23559 [ADCE] Add control dependence computation
D23225 [ADCE] Modify data structures to support removing control flow
D23065 [ADCE] Refactor anticipating new functionality (NFC)
D23102 [ADCE] Refactoring for new functionality (NFC)

Reviewers: dberlin, majnemer, nadav, mehdi_amini

Subscribers: llvm-commits, david2050, freik, twoh

Differential Revision: https://reviews.llvm.org/D24918

Added:
    llvm/trunk/test/Transforms/ADCE/2016-09-06.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/ADCE.cpp
    llvm/trunk/test/Transforms/ADCE/2002-05-23-ZeroArgPHITest.ll
    llvm/trunk/test/Transforms/ADCE/2002-05-28-Crash-distilled.ll
    llvm/trunk/test/Transforms/ADCE/2002-05-28-Crash.ll
    llvm/trunk/test/Transforms/ADCE/2002-07-17-AssertionFailure.ll
    llvm/trunk/test/Transforms/ADCE/2002-07-17-PHIAssertion.ll
    llvm/trunk/test/Transforms/ADCE/2002-07-29-Segfault.ll
    llvm/trunk/test/Transforms/ADCE/2003-01-22-PredecessorProblem.ll
    llvm/trunk/test/Transforms/ADCE/2003-04-25-PHIPostDominateProblem.ll
    llvm/trunk/test/Transforms/ADCE/2003-06-11-InvalidCFG.ll
    llvm/trunk/test/Transforms/ADCE/2003-06-24-BadSuccessor.ll
    llvm/trunk/test/Transforms/ADCE/2003-06-24-BasicFunctionality.ll
    llvm/trunk/test/Transforms/ADCE/2003-09-15-InfLoopCrash.ll
    llvm/trunk/test/Transforms/ADCE/2003-11-16-MissingPostDominanceInfo.ll
    llvm/trunk/test/Transforms/ADCE/2004-05-04-UnreachableBlock.ll
    llvm/trunk/test/Transforms/ADCE/basictest1.ll
    llvm/trunk/test/Transforms/ADCE/basictest2.ll

Modified: llvm/trunk/lib/Transforms/Scalar/ADCE.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/ADCE.cpp?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/ADCE.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/ADCE.cpp Tue Dec 13 10:42:18 2016
@@ -17,6 +17,7 @@
 #include "llvm/Transforms/Scalar/ADCE.h"
 
 #include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/PostOrderIterator.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
@@ -26,6 +27,7 @@
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/CFG.h"
 #include "llvm/IR/DebugInfoMetadata.h"
+#include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/InstIterator.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/IntrinsicInst.h"
@@ -37,11 +39,17 @@ using namespace llvm;
 #define DEBUG_TYPE "adce"
 
 STATISTIC(NumRemoved, "Number of instructions removed");
+STATISTIC(NumBranchesRemoved, "Number of branch instructions removed");
 
 // This is a tempoary option until we change the interface
 // to this pass based on optimization level.
 static cl::opt<bool> RemoveControlFlowFlag("adce-remove-control-flow",
-                                           cl::init(false), cl::Hidden);
+                                           cl::init(true), cl::Hidden);
+
+// This option enables removing of may-be-infinite loops which have no other
+// effect.
+static cl::opt<bool> RemoveLoops("adce-remove-loops", cl::init(false),
+                                 cl::Hidden);
 
 namespace {
 /// Information about Instructions
@@ -72,8 +80,11 @@ struct BlockInfoType {
   /// Corresponding BasicBlock.
   BasicBlock *BB = nullptr;
 
-  /// Cache of BB->getTerminator()
+  /// Cache of BB->getTerminator().
   TerminatorInst *Terminator = nullptr;
+
+  /// Post-order numbering of reverse control flow graph.
+  unsigned PostOrder;
 };
 
 class AggressiveDeadCodeElimination {
@@ -97,8 +108,9 @@ class AggressiveDeadCodeElimination {
   /// Set of blocks with not known to have live terminators.
   SmallPtrSet<BasicBlock *, 16> BlocksWithDeadTerminators;
 
-  /// The set of blocks which we have determined are live in the
-  /// most recent iteration of propagating liveness.
+  /// The set of blocks which we have determined whose control
+  /// dependence sources must be live and which have not had
+  /// those dependences analyized.
   SmallPtrSet<BasicBlock *, 16> NewLiveBlocks;
 
   /// Set up auxiliary data structures for Instructions and BasicBlocks and
@@ -113,7 +125,10 @@ class AggressiveDeadCodeElimination {
   void markLiveInstructions();
   /// Mark an instruction as live.
   void markLive(Instruction *I);
-  
+  /// Mark a block as live.
+  void markLive(BlockInfoType &BB);
+  void markLive(BasicBlock *BB) { markLive(BlockInfo[BB]); }
+
   /// Mark terminators of control predecessors of a PHI node live.
   void markPhiLive(PHINode *PN);
 
@@ -130,6 +145,17 @@ class AggressiveDeadCodeElimination {
   /// was removed.
   bool removeDeadInstructions();
 
+  /// Identify connected sections of the control flow grap which have
+  /// dead terminators and rewrite the control flow graph to remove them.
+  void updateDeadRegions();
+
+  /// Set the BlockInfo::PostOrder field based on a post-order
+  /// numbering of the reverse control flow graph.
+  void computeReversePostOrder();
+
+  /// Make the terminator of this block an unconditional branch to \p Target.
+  void makeUnconditional(BasicBlock *BB, BasicBlock *Target);
+
 public:
   AggressiveDeadCodeElimination(Function &F, PostDominatorTree &PDT)
       : F(F), PDT(PDT) {}
@@ -144,7 +170,7 @@ bool AggressiveDeadCodeElimination::perf
 }
 
 static bool isUnconditionalBranch(TerminatorInst *Term) {
-  auto BR = dyn_cast<BranchInst>(Term);
+  auto *BR = dyn_cast<BranchInst>(Term);
   return BR && BR->isUnconditional();
 }
 
@@ -186,23 +212,65 @@ void AggressiveDeadCodeElimination::init
   if (!RemoveControlFlowFlag)
     return;
 
-  // This is temporary: will update with post order traveral to
-  // find loop bottoms
-  SmallPtrSet<BasicBlock *, 16> Seen;
-  for (auto &BB : F) {
-    Seen.insert(&BB);
-    TerminatorInst *Term = BB.getTerminator();
-    if (isLive(Term))
-      continue;
+  if (!RemoveLoops) {
+    // This stores state for the depth-first iterator. In addition
+    // to recording which nodes have been visited we also record whether
+    // a node is currently on the "stack" of active ancestors of the current
+    // node.
+    typedef DenseMap<BasicBlock *, bool>  StatusMap ;
+    class DFState : public StatusMap {
+    public:
+      std::pair<StatusMap::iterator, bool> insert(BasicBlock *BB) {
+        return StatusMap::insert(std::make_pair(BB, true));
+      }
 
-    for (auto Succ : successors(&BB))
-      if (Seen.count(Succ)) {
-        // back edge....
-        markLive(Term);
+      // Invoked after we have visited all children of a node.
+      void completed(BasicBlock *BB) { (*this)[BB] = false; }
+
+      // Return true if \p BB is currently on the active stack
+      // of ancestors.
+      bool onStack(BasicBlock *BB) {
+        auto Iter = find(BB);
+        return Iter != end() && Iter->second;
+      }
+    } State;
+    
+    State.reserve(F.size());
+    // Iterate over blocks in depth-first pre-order and
+    // treat all edges to a block already seen as loop back edges
+    // and mark the branch live it if there is a back edge.
+    for (auto *BB: depth_first_ext(&F.getEntryBlock(), State)) {
+      TerminatorInst *Term = BB->getTerminator();
+      if (isLive(Term))
+        continue;
+
+      for (auto *Succ : successors(BB))
+        if (State.onStack(Succ)) {
+          // back edge....
+          markLive(Term);
+          break;
+        }
+    }
+  }
+
+  // Mark blocks live if there is no path from the block to the
+  // return of the function or a successor for which this is true.
+  // This protects IDFCalculator which cannot handle such blocks.
+  for (auto &BBInfoPair : BlockInfo) {
+    auto &BBInfo = BBInfoPair.second;
+    if (BBInfo.terminatorIsLive())
+      continue;
+    auto *BB = BBInfo.BB;
+    if (!PDT.getNode(BB)) {
+      markLive(BBInfo.Terminator);
+      continue;
+    }
+    for (auto *Succ : successors(BB))
+      if (!PDT.getNode(Succ)) {
+        markLive(BBInfo.Terminator);
         break;
       }
   }
-  // End temporary handling of loops.
 
   // Mark blocks live if there is no path from the block to the
   // return of the function or a successor for which this is true.
@@ -218,7 +286,7 @@ void AggressiveDeadCodeElimination::init
       markLive(BBInfo.Terminator);
       continue;
     }
-    for (auto Succ : successors(BB))
+    for (auto *Succ : successors(BB))
       if (!PDT.getNode(Succ)) {
         DEBUG(dbgs() << "Successor not post-dominated by return: "
                      << BB->getName() << '\n';);
@@ -278,32 +346,19 @@ void AggressiveDeadCodeElimination::mark
       Instruction *LiveInst = Worklist.pop_back_val();
       DEBUG(dbgs() << "work live: "; LiveInst->dump(););
 
-      // Collect the live debug info scopes attached to this instruction.
-      if (const DILocation *DL = LiveInst->getDebugLoc())
-        collectLiveScopes(*DL);
-
       for (Use &OI : LiveInst->operands())
         if (Instruction *Inst = dyn_cast<Instruction>(OI))
           markLive(Inst);
-      
+
       if (auto *PN = dyn_cast<PHINode>(LiveInst))
         markPhiLive(PN);
     }
+
+    // After data flow liveness has been identified, examine which branch
+    // decisions are required to determine live instructions are executed.
     markLiveBranchesFromControlDependences();
 
-    if (Worklist.empty()) {
-      // Temporary until we can actually delete branches.
-      SmallVector<TerminatorInst *, 16> DeadTerminators;
-      for (auto *BB : BlocksWithDeadTerminators)
-        DeadTerminators.push_back(BB->getTerminator());
-      for (auto *I : DeadTerminators)
-        markLive(I);
-      assert(BlocksWithDeadTerminators.empty());
-      // End temporary.
-    }
   } while (!Worklist.empty());
-
-  assert(BlocksWithDeadTerminators.empty());
 }
 
 void AggressiveDeadCodeElimination::markLive(Instruction *I) {
@@ -316,13 +371,26 @@ void AggressiveDeadCodeElimination::mark
   Info.Live = true;
   Worklist.push_back(I);
 
+  // Collect the live debug info scopes attached to this instruction.
+  if (const DILocation *DL = I->getDebugLoc())
+    collectLiveScopes(*DL);
+
   // Mark the containing block live
   auto &BBInfo = *Info.Block;
-  if (BBInfo.Terminator == I)
+  if (BBInfo.Terminator == I) {
     BlocksWithDeadTerminators.erase(BBInfo.BB);
+    // For live terminators, mark destination blocks
+    // live to preserve this control flow edges.
+    if (!BBInfo.UnconditionalBranch)
+      for (auto *BB : successors(I->getParent()))
+        markLive(BB);
+  }
+  markLive(BBInfo);
+}
+
+void AggressiveDeadCodeElimination::markLive(BlockInfoType &BBInfo) {
   if (BBInfo.Live)
     return;
-
   DEBUG(dbgs() << "mark block live: " << BBInfo.BB->getName() << '\n');
   BBInfo.Live = true;
   if (!BBInfo.CFLive) {
@@ -332,7 +400,7 @@ void AggressiveDeadCodeElimination::mark
 
   // Mark unconditional branches at the end of live
   // blocks as live since there is no work to do for them later
-  if (BBInfo.UnconditionalBranch && I != BBInfo.Terminator)
+  if (BBInfo.UnconditionalBranch)
     markLive(BBInfo.Terminator);
 }
 
@@ -408,7 +476,7 @@ void AggressiveDeadCodeElimination::mark
   NewLiveBlocks.clear();
 
   // Dead terminators which control live blocks are now marked live.
-  for (auto BB : IDFBlocks) {
+  for (auto *BB : IDFBlocks) {
     DEBUG(dbgs() << "live control in: " << BB->getName() << '\n');
     markLive(BB->getTerminator());
   }
@@ -421,8 +489,33 @@ void AggressiveDeadCodeElimination::mark
 //===----------------------------------------------------------------------===//
 bool AggressiveDeadCodeElimination::removeDeadInstructions() {
 
+  // Updates control and dataflow around dead blocks
+  updateDeadRegions();
+
+  DEBUG({
+    for (Instruction &I : instructions(F)) {
+      // Check if the instruction is alive.
+      if (isLive(&I))
+        continue;
+
+      if (auto *DII = dyn_cast<DbgInfoIntrinsic>(&I)) {
+        // Check if the scope of this variable location is alive.
+        if (AliveScopes.count(DII->getDebugLoc()->getScope()))
+          continue;
+
+        // If intrinsic is pointing at a live SSA value, there may be an
+        // earlier optimization bug: if we know the location of the variable,
+        // why isn't the scope of the location alive?
+        if (Value *V = DII->getVariableLocation())
+          if (Instruction *II = dyn_cast<Instruction>(V))
+            if (isLive(II))
+              dbgs() << "Dropping debug info for " << *DII << "\n";
+      }
+    }
+  });
+
   // The inverse of the live set is the dead set.  These are those instructions
-  // which have no side effects and do not influence the control flow or return
+  // that have no side effects and do not influence the control flow or return
   // value of the function, and may therefore be deleted safely.
   // NOTE: We reuse the Worklist vector here for memory efficiency.
   for (Instruction &I : instructions(F)) {
@@ -430,23 +523,12 @@ bool AggressiveDeadCodeElimination::remo
     if (isLive(&I))
       continue;
 
-    assert(!I.isTerminator() && "NYI: Removing Control Flow");
-
     if (auto *DII = dyn_cast<DbgInfoIntrinsic>(&I)) {
       // Check if the scope of this variable location is alive.
       if (AliveScopes.count(DII->getDebugLoc()->getScope()))
         continue;
 
       // Fallthrough and drop the intrinsic.
-      DEBUG({
-        // If intrinsic is pointing at a live SSA value, there may be an
-        // earlier optimization bug: if we know the location of the variable,
-        // why isn't the scope of the location alive?
-        if (Value *V = DII->getVariableLocation())
-          if (Instruction *II = dyn_cast<Instruction>(V))
-            if (isLive(II))
-              dbgs() << "Dropping debug info for " << *DII << "\n";
-      });
     }
 
     // Prepare to delete.
@@ -462,6 +544,96 @@ bool AggressiveDeadCodeElimination::remo
   return !Worklist.empty();
 }
 
+// A dead region is the set of dead blocks with a common live post-dominator.
+void AggressiveDeadCodeElimination::updateDeadRegions() {
+
+  DEBUG({
+    dbgs() << "final dead terminator blocks: " << '\n';
+    for (auto *BB : BlocksWithDeadTerminators)
+      dbgs() << '\t' << BB->getName()
+             << (BlockInfo[BB].Live ? " LIVE\n" : "\n");
+  });
+
+  // Don't compute the post ordering unless we needed it.
+  bool HavePostOrder = false;
+
+  for (auto *BB : BlocksWithDeadTerminators) {
+    auto &Info = BlockInfo[BB];
+    if (Info.UnconditionalBranch) {
+      InstInfo[Info.Terminator].Live = true;
+      continue;
+    }
+
+    if (!HavePostOrder) {
+      computeReversePostOrder();
+      HavePostOrder = true;
+    }
+
+    // Add an unconditional branch to the successor closest to the
+    // end of the function which insures a path to the exit for each
+    // live edge.
+    BlockInfoType *PreferredSucc = nullptr;
+    for (auto *Succ : successors(BB)) {
+      auto *Info = &BlockInfo[Succ];
+      if (!PreferredSucc || PreferredSucc->PostOrder < Info->PostOrder)
+        PreferredSucc = Info;
+    }
+    assert((PreferredSucc && PreferredSucc->PostOrder > 0) &&
+           "Failed to find safe successor for dead branc");
+    bool First = true;
+    for (auto *Succ : successors(BB)) {
+      if (!First || Succ != PreferredSucc->BB)
+        Succ->removePredecessor(BB);
+      else
+        First = false;
+    }
+    makeUnconditional(BB, PreferredSucc->BB);
+    NumBranchesRemoved += 1;
+  }
+}
+
+// reverse top-sort order
+void AggressiveDeadCodeElimination::computeReversePostOrder() {
+  
+  // This provides a post-order numbering of the reverse conrtol flow graph
+  // Note that it is incomplete in the presence of infinite loops but we don't
+  // need numbers blocks which don't reach the end of the functions since
+  // all branches in those blocks are forced live.
+  
+  // For each block without successors, extend the DFS from the bloack
+  // backward through the graph
+  SmallPtrSet<BasicBlock*, 16> Visited;
+  unsigned PostOrder = 0;
+  for (auto &BB : F) {
+    if (succ_begin(&BB) != succ_end(&BB))
+      continue;
+    for (BasicBlock *Block : inverse_post_order_ext(&BB,Visited))
+      BlockInfo[Block].PostOrder = PostOrder++;
+  }
+}
+
+void AggressiveDeadCodeElimination::makeUnconditional(BasicBlock *BB,
+                                                      BasicBlock *Target) {
+  TerminatorInst *PredTerm = BB->getTerminator();
+  // Collect the live debug info scopes attached to this instruction.
+  if (const DILocation *DL = PredTerm->getDebugLoc())
+    collectLiveScopes(*DL);
+
+  // Just mark live an existing unconditional branch
+  if (isUnconditionalBranch(PredTerm)) {
+    PredTerm->setSuccessor(0, Target);
+    InstInfo[PredTerm].Live = true;
+    return;
+  }
+  DEBUG(dbgs() << "making unconditional " << BB->getName() << '\n');
+  NumBranchesRemoved += 1;
+  IRBuilder<> Builder(PredTerm);
+  auto *NewTerm = Builder.CreateBr(Target);
+  InstInfo[NewTerm].Live = true;
+  if (const DILocation *DL = PredTerm->getDebugLoc())
+    NewTerm->setDebugLoc(DL);
+}
+
 //===----------------------------------------------------------------------===//
 //
 // Pass Manager integration code
@@ -494,7 +666,8 @@ struct ADCELegacyPass : public FunctionP
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.addRequired<PostDominatorTreeWrapperPass>();
-    AU.setPreservesCFG(); // TODO -- will remove when we start removing branches
+    if (!RemoveControlFlowFlag)
+      AU.setPreservesCFG();
     AU.addPreserved<GlobalsAAWrapperPass>();
   }
 };

Modified: llvm/trunk/test/Transforms/ADCE/2002-05-23-ZeroArgPHITest.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2002-05-23-ZeroArgPHITest.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2002-05-23-ZeroArgPHITest.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2002-05-23-ZeroArgPHITest.ll Tue Dec 13 10:42:18 2016
@@ -4,7 +4,8 @@
 ; removed even though there were uses still around.  Now the uses are filled
 ; in with a dummy value before the PHI is deleted.
 ;
-; RUN: opt < %s -adce
+; RUN: opt < %s -S -adce | grep bb1
+; RUN: opt < %s -S -adce -adce-remove-loops | FileCheck %s
 	
         %node_t = type { double*, %node_t*, %node_t**, double**, double*, i32, i32 }
 
@@ -17,6 +18,7 @@ bb0:
 bb1:            ; preds = %bb0
         %reg107 = load %node_t*, %node_t** %nodelist.upgrd.1              ; <%node_t*> [#uses=2]
         %cond211 = icmp eq %node_t* %reg107, null               ; <i1> [#uses=1]
+; CHECK: br label %bb3
         br i1 %cond211, label %bb3, label %bb2
 
 bb2:            ; preds = %bb2, %bb1
@@ -24,6 +26,7 @@ bb2:            ; preds = %bb2, %bb1
         %reg212 = getelementptr %node_t, %node_t* %reg109, i64 0, i32 1          ; <%node_t**> [#uses=1]
         %reg110 = load %node_t*, %node_t** %reg212                ; <%node_t*> [#uses=2]
         %cond213 = icmp ne %node_t* %reg110, null               ; <i1> [#uses=1]
+; CHECK: br label %bb3
         br i1 %cond213, label %bb2, label %bb3
 
 bb3:            ; preds = %bb2, %bb1

Modified: llvm/trunk/test/Transforms/ADCE/2002-05-28-Crash-distilled.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2002-05-28-Crash-distilled.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2002-05-28-Crash-distilled.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2002-05-28-Crash-distilled.ll Tue Dec 13 10:42:18 2016
@@ -1,6 +1,7 @@
 ; This testcase is a distilled form of: 2002-05-28-Crash.ll
 
 ; RUN: opt < %s -adce 
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
 
 define float @test(i32 %i) {
         %F = sitofp i32 %i to float             ; <float> [#uses=1]
@@ -9,6 +10,7 @@ define float @test(i32 %i) {
 
 Loop:           ; preds = %Loop, %0
         %B = icmp ne i32 %I, 0          ; <i1> [#uses=1]
+; CHECK:   br label %Out
         br i1 %B, label %Out, label %Loop
 
 Out:            ; preds = %Loop

Modified: llvm/trunk/test/Transforms/ADCE/2002-05-28-Crash.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2002-05-28-Crash.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2002-05-28-Crash.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2002-05-28-Crash.ll Tue Dec 13 10:42:18 2016
@@ -12,6 +12,7 @@
 ;}
 ;
 ; RUN: opt < %s -adce
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
 
 define i32 @rx_bitset_empty(i32 %size, i32* %set) {
 bb1:
@@ -28,6 +29,7 @@ bb1:
         %reg124 = getelementptr i32, i32* %set, i64 %reg114-idxcast-offset.upgrd.1           ; <i32*> [#uses=1]
         %reg125 = load i32, i32* %reg124             ; <i32> [#uses=1]
         %cond232 = icmp ne i32 %reg125, 0               ; <i1> [#uses=1]
+; CHECK: br label %bb3
         br i1 %cond232, label %bb3, label %bb2
 
 bb2:            ; preds = %bb2, %bb1

Modified: llvm/trunk/test/Transforms/ADCE/2002-07-17-AssertionFailure.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2002-07-17-AssertionFailure.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2002-07-17-AssertionFailure.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2002-07-17-AssertionFailure.ll Tue Dec 13 10:42:18 2016
@@ -3,11 +3,12 @@
 ; block in this function, it would work fine, but that would be the part we 
 ; have to fix now, wouldn't it....
 ;
-; RUN: opt < %s -adce
+; RUN: opt < %s -adce -S | FileCheck %s
 
 define void @foo(i8* %reg5481) {
         %cast611 = bitcast i8* %reg5481 to i8**         ; <i8**> [#uses=1]
         %reg162 = load i8*, i8** %cast611            ; <i8*> [#uses=1]
+; CHECK-NOT: ptrtoint
         ptrtoint i8* %reg162 to i32             ; <i32>:1 [#uses=0]
         ret void
 }

Modified: llvm/trunk/test/Transforms/ADCE/2002-07-17-PHIAssertion.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2002-07-17-PHIAssertion.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2002-07-17-PHIAssertion.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2002-07-17-PHIAssertion.ll Tue Dec 13 10:42:18 2016
@@ -1,6 +1,6 @@
 ; This testcase was extracted from the gzip SPEC benchmark
 ;
-; RUN: opt < %s -adce
+; RUN: opt < %s -adce | FileCheck %s
 
 @bk = external global i32               ; <i32*> [#uses=2]
 @hufts = external global i32            ; <i32*> [#uses=1]
@@ -16,6 +16,8 @@ bb2:            ; preds = %bb6, %bb0
 bb3:            ; preds = %bb2
         br label %UnifiedExitNode
 
+; CHECK-NOT: bb4:
+; CHECK-NOT: bb5:
 bb4:            ; preds = %bb2
         %reg117 = load i32, i32* @hufts              ; <i32> [#uses=2]
         %cond241 = icmp ule i32 %reg117, %reg128                ; <i1> [#uses=1]

Modified: llvm/trunk/test/Transforms/ADCE/2002-07-29-Segfault.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2002-07-29-Segfault.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2002-07-29-Segfault.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2002-07-29-Segfault.ll Tue Dec 13 10:42:18 2016
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -adce -disable-output
+; RUN: opt < %s -adce -disable-output -adce-remove-loops
 
 define void @test() {
         br label %BB3

Modified: llvm/trunk/test/Transforms/ADCE/2003-01-22-PredecessorProblem.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2003-01-22-PredecessorProblem.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2003-01-22-PredecessorProblem.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2003-01-22-PredecessorProblem.ll Tue Dec 13 10:42:18 2016
@@ -1,5 +1,6 @@
 ; Testcase reduced from 197.parser by bugpoint
 ; RUN: opt < %s -adce 
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
 
 define void @conjunction_prune() {
 ; <label>:0
@@ -7,16 +8,20 @@ define void @conjunction_prune() {
 
 bb19:           ; preds = %bb23, %bb22, %0
         %reg205 = phi i8* [ null, %bb22 ], [ null, %bb23 ], [ null, %0 ]                ; <i8*> [#uses=1]
+; CHECK: br label %bb22
         br i1 false, label %bb21, label %bb22
 
 bb21:           ; preds = %bb19
         %cast455 = bitcast i8* %reg205 to i8**          ; <i8**> [#uses=0]
+; CHECK: br label %bb22
         br label %bb22
 
 bb22:           ; preds = %bb21, %bb19
+; CHECK: br label %bb23
         br i1 false, label %bb19, label %bb23
 
 bb23:           ; preds = %bb22
+; CHECK: br label %bb28
         br i1 false, label %bb19, label %bb28
 
 bb28:           ; preds = %bb23

Modified: llvm/trunk/test/Transforms/ADCE/2003-04-25-PHIPostDominateProblem.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2003-04-25-PHIPostDominateProblem.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2003-04-25-PHIPostDominateProblem.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2003-04-25-PHIPostDominateProblem.ll Tue Dec 13 10:42:18 2016
@@ -2,7 +2,8 @@
 ; entries for it's postdominator.  But I think this can only happen when the 
 ; PHI node is dead, so we just avoid patching up dead PHI nodes.
 
-; RUN: opt < %s -adce
+; RUN: opt < %s -adce                    -S | FileCheck %s
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
 
 target datalayout = "e-p:32:32"
 
@@ -15,6 +16,7 @@ loopentry:              ; preds = %endif
         br i1 false, label %no_exit, label %return
 
 no_exit:                ; preds = %loopentry
+; CHECK: br label %then
         br i1 false, label %then, label %else
 
 then:           ; preds = %no_exit

Modified: llvm/trunk/test/Transforms/ADCE/2003-06-11-InvalidCFG.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2003-06-11-InvalidCFG.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2003-06-11-InvalidCFG.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2003-06-11-InvalidCFG.ll Tue Dec 13 10:42:18 2016
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -adce -disable-output
+; RUN: opt < %s -adce -adce-remove-loops -disable-output
 
 @G = external global i32*               ; <i32**> [#uses=1]
 

Modified: llvm/trunk/test/Transforms/ADCE/2003-06-24-BadSuccessor.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2003-06-24-BadSuccessor.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2003-06-24-BadSuccessor.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2003-06-24-BadSuccessor.ll Tue Dec 13 10:42:18 2016
@@ -1,4 +1,6 @@
 ; RUN: opt < %s -adce -disable-output
+; RUN: opt < %s -adce -adce-remove-loops=true -disable-output
+
 target datalayout = "e-p:32:32"
 	%struct..CppObjTypeDesc = type { i32, i16, i16 }
 	%struct..TypeToken = type { i32, i16, i16 }
@@ -30,6 +32,7 @@ loopentry.1:		; preds = %then.53, %endif
 	br i1 false, label %no_exit.1, label %loopentry.0
 
 no_exit.1:		; preds = %loopentry.1
+; CHECK: switch
 	switch i32 0, label %label.17 [
 		 i32 2, label %label.11
 		 i32 19, label %label.10

Modified: llvm/trunk/test/Transforms/ADCE/2003-06-24-BasicFunctionality.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2003-06-24-BasicFunctionality.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2003-06-24-BasicFunctionality.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2003-06-24-BasicFunctionality.ll Tue Dec 13 10:42:18 2016
@@ -1,4 +1,5 @@
-; RUN: opt < %s -adce -simplifycfg -S | not grep then:
+; RUN: opt < %s -adce -S | FileCheck %s
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
 
 define void @dead_test8(i32* %data.1, i32 %idx.1) {
 entry:
@@ -17,7 +18,9 @@ no_exit:                ; preds = %endif
         %i.0 = phi i32 [ %inc.1, %endif ], [ 0, %no_exit.preheader ]            ; <i32> [#uses=1]
         %tmp.12 = load i32, i32* %tmp.11             ; <i32> [#uses=1]
         %tmp.14 = sub i32 0, %tmp.12            ; <i32> [#uses=1]
+; CHECK-NOT: %tmp.161
         %tmp.161 = icmp ne i32 %k.1, %tmp.14            ; <i1> [#uses=1]
+; CHECK: br label %then
         br i1 %tmp.161, label %then, label %else
 
 then:           ; preds = %no_exit

Modified: llvm/trunk/test/Transforms/ADCE/2003-09-15-InfLoopCrash.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2003-09-15-InfLoopCrash.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2003-09-15-InfLoopCrash.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2003-09-15-InfLoopCrash.ll Tue Dec 13 10:42:18 2016
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -adce -disable-output
+; RUN: opt < %s -adce -adce-remove-loops -disable-output
 
 define i32 @main() {
         br label %loop

Modified: llvm/trunk/test/Transforms/ADCE/2003-11-16-MissingPostDominanceInfo.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2003-11-16-MissingPostDominanceInfo.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2003-11-16-MissingPostDominanceInfo.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2003-11-16-MissingPostDominanceInfo.ll Tue Dec 13 10:42:18 2016
@@ -1,4 +1,6 @@
 ; RUN: opt < %s -adce -simplifycfg -S | grep call
+; RUN: opt < %s -adce -adce-remove-loops -simplifycfg -S | grep call
+
 declare void @exit(i32)
 
 define i32 @main(i32 %argc) {

Modified: llvm/trunk/test/Transforms/ADCE/2004-05-04-UnreachableBlock.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2004-05-04-UnreachableBlock.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2004-05-04-UnreachableBlock.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/2004-05-04-UnreachableBlock.ll Tue Dec 13 10:42:18 2016
@@ -1,4 +1,5 @@
 ; RUN: opt < %s -adce -disable-output
+; RUN: opt < %s -adce -adce-remove-loops -disable-output
 
 define void @test() {
 entry:

Added: llvm/trunk/test/Transforms/ADCE/2016-09-06.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/2016-09-06.ll?rev=289548&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/2016-09-06.ll (added)
+++ llvm/trunk/test/Transforms/ADCE/2016-09-06.ll Tue Dec 13 10:42:18 2016
@@ -0,0 +1,55 @@
+; RUN: opt < %s -sroa -adce -adce-remove-loops -S | FileCheck %s
+; ModuleID = 'test1.bc'
+source_filename = "test1.c"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind uwtable
+define i32 @foo(i32, i32, i32) #0 {
+  %4 = alloca i32, align 4
+  %5 = alloca i32, align 4
+  %6 = alloca i32, align 4
+  %7 = alloca i32, align 4
+  %8 = alloca i32, align 4
+  store i32 %0, i32* %4, align 4
+  store i32 %1, i32* %5, align 4
+  store i32 %2, i32* %6, align 4
+  store i32 0, i32* %7, align 4
+  %9 = load i32, i32* %5, align 4
+  %I10 = icmp ne i32 %9, 0
+  br i1 %I10, label %B11, label %B21
+
+B11: 
+  store i32 0, i32* %8, align 4
+  br label %B12
+
+B12:
+  %I13 = load i32, i32* %8, align 4
+  %I14 = load i32, i32* %6, align 4
+  %I15 = icmp slt i32 %I13, %I14
+; CHECK: br label %B20
+  br i1 %I15, label %B16, label %B20
+
+B16: 
+  br label %B17
+
+B17: 
+  %I18 = load i32, i32* %8, align 4
+  %I19 = add nsw i32 %I18, 1
+  store i32 %I19, i32* %8, align 4
+  br label %B12
+
+B20:
+  store i32 1, i32* %7, align 4
+  br label %B21
+
+B21: 
+  %I22 = load i32, i32* %7, align 4
+  ret i32 %I22
+}
+
+attributes #0 = { nounwind uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.ident = !{!0}
+
+!0 = !{!"clang version 4.0.0 (http://llvm.org/git/clang.git 5864a13abf4490e76ae2eb0896198e1305927df2)"}

Modified: llvm/trunk/test/Transforms/ADCE/basictest1.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/basictest1.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/basictest1.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/basictest1.ll Tue Dec 13 10:42:18 2016
@@ -1,4 +1,6 @@
-; RUN: opt < %s -adce -simplifycfg | llvm-dis	
+; RUN: opt < %s -adce -S | FileCheck %s
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
+
 %FILE = type { i32, i8*, i8*, i8, i8, i32, i32, i32 }
 	%spec_fd_t = type { i32, i32, i32, i8* }
 @__iob = external global [20 x %FILE]		; <[20 x %FILE]*> [#uses=1]
@@ -24,6 +26,7 @@ declare void @perror(i8*)
 define i32 @spec_getc(i32 %fd) {
 	%reg109 = load i32, i32* @dbglvl		; <i32> [#uses=1]
 	%cond266 = icmp sle i32 %reg109, 4		; <i1> [#uses=1]
+; CHECKL br label %bb3
 	br i1 %cond266, label %bb3, label %bb2
 
 bb2:		; preds = %0
@@ -55,6 +58,7 @@ bb5:		; preds = %bb3
 bb6:		; preds = %bb5
 	%reg134 = load i32, i32* @dbglvl		; <i32> [#uses=1]
 	%cond271 = icmp sle i32 %reg134, 4		; <i1> [#uses=1]
+; CHECK: br label %bb8
 	br i1 %cond271, label %bb8, label %bb7
 
 bb7:		; preds = %bb6
@@ -77,6 +81,7 @@ bb9:		; preds = %bb5
 	store i32 %reg157, i32* %idx5
 	%reg163 = load i32, i32* @dbglvl		; <i32> [#uses=1]
 	%cond272 = icmp sle i32 %reg163, 4		; <i1> [#uses=1]
+; CHECK: br label %bb11
 	br i1 %cond272, label %bb11, label %bb10
 
 bb10:		; preds = %bb9

Modified: llvm/trunk/test/Transforms/ADCE/basictest2.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ADCE/basictest2.ll?rev=289548&r1=289547&r2=289548&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ADCE/basictest2.ll (original)
+++ llvm/trunk/test/Transforms/ADCE/basictest2.ll Tue Dec 13 10:42:18 2016
@@ -1,4 +1,6 @@
-; RUN: opt < %s -adce -simplifycfg | llvm-dis
+; RUN: opt < %s -adce -disable-output
+; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
+
 	%FILE = type { i32, i8*, i8*, i8, i8, i32, i32, i32 }
 	%spec_fd_t = type { i32, i32, i32, i8* }
 @__iob = external global [20 x %FILE]		; <[20 x %FILE]*> [#uses=1]
@@ -24,6 +26,7 @@ declare void @perror(i8*)
 define i32 @spec_getc(i32 %fd) {
 	%reg109 = load i32, i32* @dbglvl		; <i32> [#uses=1]
 	%cond266 = icmp sle i32 %reg109, 4		; <i1> [#uses=1]
+; CHECK: br label %bb3
 	br i1 %cond266, label %bb3, label %bb2
 
 bb2:		; preds = %0
@@ -55,6 +58,7 @@ bb5:		; preds = %bb3
 bb6:		; preds = %bb5
 	%reg134 = load i32, i32* @dbglvl		; <i32> [#uses=1]
 	%cond271 = icmp sle i32 %reg134, 4		; <i1> [#uses=1]
+; CHECK: br label %bb8
 	br i1 %cond271, label %bb8, label %bb7
 
 bb7:		; preds = %bb6
@@ -77,6 +81,7 @@ bb9:		; preds = %bb5
 	store i32 %reg157, i32* %idx5
 	%reg163 = load i32, i32* @dbglvl		; <i32> [#uses=1]
 	%cond272 = icmp sle i32 %reg163, 4		; <i1> [#uses=1]
+; CHECK: br label %bb11
 	br i1 %cond272, label %bb11, label %bb10
 
 bb10:		; preds = %bb9




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