[llvm] r265388 - Adds the ability to use an epilog remainder loop during loop unrolling and makes

Michael Zolotukhin via llvm-commits llvm-commits at lists.llvm.org
Mon Jul 11 18:04:56 PDT 2016


> On Apr 22, 2016, at 11:35 AM, Michael Zolotukhin <mzolotukhin at apple.com> wrote:
> 
> 
>> On Apr 20, 2016, at 4:43 PM, Evgeny Stupachenko <evstupac at gmail.com> wrote:
>> 
>> Hi,
>> 
>> Yes if the test is that important. However I believe that the
>> regression caused randomly, but not by epilog unrolling.
>> On my Corei7 "I was able to reproduce it only in 32 bit mode, 64 bit
>> mode epilog is ~30% faster.".
>> The analysis showed no critical changes in the hottest loop.
>> 
>> As for LSR issue.
>> Sorry for missing your request for posting PR. I'm preparing LSR patch
>> fixing the issue. And issue itself is related to already filed PR23384
>> (on an inefficient x86 LSR transformation).
Hi Evgeny,

Is there any progress with the LSR patch? Or is there something blocking you?

Thanks,
Michael
> Hi Evgeny,
> 
> It’s fine with me to keep it on, I just want to make sure we address the regression. So, if you’re working on the patch, there are no concerns from my side.
> 
> Thanks,
> Michael
> 
>> 
>> Thanks,
>> Evgeny
>> 
>> On Wed, Apr 20, 2016 at 11:41 AM, Michael Zolotukhin
>> <mzolotukhin at apple.com> wrote:
>>> Hi,
>>> 
>>> Could we change the default value to the original one until this 90%
>>> regression is addressed?
>>> 
>>> Thanks,
>>> Michael
>>> 
>>> On Apr 15, 2016, at 12:37 PM, Mikhail Zolotukhin <mzolotukhin at apple.com>
>>> wrote:
>>> 
>>> 
>>> On Apr 8, 2016, at 5:39 PM, Evgeny Stupachenko <evstupac at gmail.com> wrote:
>>> 
>>> Investigation showed that the regression is most likely LSR related,
>>> but not loop unroll.
>>> I was able to reproduce it only in 32 bit mode, 64 bit mode epilog is
>>> ~30% faster.
>>> 
>>> Going back to the changes in the test. Epilog variant has 1 move more
>>> in the hottest loop (which is redundant and should be deleted) and use
>>> constant address in moves inside the loop. However manual deleting of
>>> the move does not give any significant performance gain.
>>> The different behavior of LSR comes from additional inductive variable
>>> in unrolled loop. For Epilog case we add "k" (supposed to be
>>> eliminated after LSR):
>>> 
>>> k = n - n % (unroll factor));
>>> ...
>>> access a[i];
>>> i++;
>>> k--;
>>> if (!k) break;
>>> 
>>> Moving code of the loop modifying "palign" before loop showed up to 2
>>> times perf difference. So most likely epilog unroll itself does not
>>> influence on performance here.
>>> However, the fact that LSR leave constant address inside the loop
>>> moves (making them much longer), should be addressed to LSR. I'll
>>> submit a bug report on this.
>>> 
>>> Hi Evgeny,
>>> 
>>> Could you please post the PR number here as well?
>>> 
>>> Michael
>>> 
>>> 
>>> 
>>> On Fri, Apr 8, 2016 at 2:09 PM, Evgeny Stupachenko <evstupac at gmail.com>
>>> wrote:
>>> 
>>> Hi Michael,
>>> 
>>> Yes I do have the data.
>>> There were ~10% improvements on some EEMBC tests; spec2000 performance
>>> was almost flat (within 2%).
>>> 
>>> Let me look into BubbleSort case and come back with analysis and
>>> possible improvement.
>>> 
>>> Thanks,
>>> Evgeny
>>> 
>>> 
>>> On Fri, Apr 8, 2016 at 1:23 PM, Michael Zolotukhin via llvm-commits
>>> <llvm-commits at lists.llvm.org> wrote:
>>> 
>>> Hi Evgeny,
>>> 
>>> We’ve found several performance regressions on LLVM testsuite caused by this
>>> patch. Do you have a data from your performance experiments to back-up the
>>> decision to make epilogues the default strategy?
>>> 
>>> One of the biggest regressions we see is 89% on
>>> SingleSource/Benchmarks/Stanford/Bubblesort (on x86), while the biggest gain
>>> is only 30%.
>>> 
>>> Thanks,
>>> Michael
>>> 
>>> 
>>> On Apr 5, 2016, at 5:19 AM, David L Kreitzer via llvm-commits
>>> <llvm-commits at lists.llvm.org> wrote:
>>> 
>>> Author: dlkreitz
>>> Date: Tue Apr  5 07:19:35 2016
>>> New Revision: 265388
>>> 
>>> URL: http://llvm.org/viewvc/llvm-project?rev=265388&view=rev
>>> Log:
>>> Adds the ability to use an epilog remainder loop during loop unrolling and
>>> makes
>>> this the default behavior.
>>> 
>>> Patch by Evgeny Stupachenko (evstupac at gmail.com).
>>> 
>>> Differential Revision: http://reviews.llvm.org/D18158
>>> 
>>> Modified:
>>> llvm/trunk/include/llvm/Transforms/Utils/UnrollLoop.h
>>> llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp
>>> llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp
>>> llvm/trunk/test/Transforms/LoopUnroll/AArch64/runtime-loop.ll
>>> llvm/trunk/test/Transforms/LoopUnroll/PowerPC/a2-unrolling.ll
>>> llvm/trunk/test/Transforms/LoopUnroll/X86/mmx.ll
>>> llvm/trunk/test/Transforms/LoopUnroll/high-cost-trip-count-computation.ll
>>> llvm/trunk/test/Transforms/LoopUnroll/runtime-loop.ll
>>> llvm/trunk/test/Transforms/LoopUnroll/runtime-loop1.ll
>>> llvm/trunk/test/Transforms/LoopUnroll/runtime-loop2.ll
>>> llvm/trunk/test/Transforms/LoopUnroll/runtime-loop4.ll
>>> llvm/trunk/test/Transforms/LoopUnroll/runtime-loop5.ll
>>> llvm/trunk/test/Transforms/LoopUnroll/tripcount-overflow.ll
>>> llvm/trunk/test/Transforms/LoopUnroll/unroll-cleanup.ll
>>> llvm/trunk/test/Transforms/LoopUnroll/unroll-pragmas.ll
>>> 
>>> Modified: llvm/trunk/include/llvm/Transforms/Utils/UnrollLoop.h
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/UnrollLoop.h?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/include/llvm/Transforms/Utils/UnrollLoop.h (original)
>>> +++ llvm/trunk/include/llvm/Transforms/Utils/UnrollLoop.h Tue Apr  5
>>> 07:19:35 2016
>>> @@ -34,10 +34,11 @@ bool UnrollLoop(Loop *L, unsigned Count,
>>>             LoopInfo *LI, ScalarEvolution *SE, DominatorTree *DT,
>>>             AssumptionCache *AC, bool PreserveLCSSA);
>>> 
>>> -bool UnrollRuntimeLoopProlog(Loop *L, unsigned Count,
>>> -                             bool AllowExpensiveTripCount, LoopInfo *LI,
>>> -                             ScalarEvolution *SE, DominatorTree *DT,
>>> -                             bool PreserveLCSSA);
>>> +bool UnrollRuntimeLoopRemainder(Loop *L, unsigned Count,
>>> +                                bool AllowExpensiveTripCount,
>>> +                                bool UseEpilogRemainder, LoopInfo *LI,
>>> +                                ScalarEvolution *SE, DominatorTree *DT,
>>> +                                bool PreserveLCSSA);
>>> 
>>> MDNode *GetUnrollMetadata(MDNode *LoopID, StringRef Name);
>>> }
>>> 
>>> Modified: llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp (original)
>>> +++ llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp Tue Apr  5 07:19:35 2016
>>> @@ -44,6 +44,11 @@ using namespace llvm;
>>> STATISTIC(NumCompletelyUnrolled, "Number of loops completely unrolled");
>>> STATISTIC(NumUnrolled, "Number of loops unrolled (completely or
>>> otherwise)");
>>> 
>>> +static cl::opt<bool>
>>> +UnrollRuntimeEpilog("unroll-runtime-epilog", cl::init(true), cl::Hidden,
>>> +                    cl::desc("Allow runtime unrolled loops to be unrolled "
>>> +                             "with epilog instead of prolog."));
>>> +
>>> /// Convert the instruction operands from referencing the current values
>>> into
>>> /// those specified by VMap.
>>> static inline void remapInstruction(Instruction *I,
>>> @@ -288,12 +293,13 @@ bool llvm::UnrollLoop(Loop *L, unsigned
>>>            "convergent "
>>>            "operation.");
>>>   });
>>> -  // Don't output the runtime loop prolog if Count is a multiple of
>>> -  // TripMultiple.  Such a prolog is never needed, and is unsafe if the
>>> loop
>>> +  // Don't output the runtime loop remainder if Count is a multiple of
>>> +  // TripMultiple.  Such a remainder is never needed, and is unsafe if the
>>> loop
>>> // contains a convergent instruction.
>>> if (RuntimeTripCount && TripMultiple % Count != 0 &&
>>> -      !UnrollRuntimeLoopProlog(L, Count, AllowExpensiveTripCount, LI, SE,
>>> DT,
>>> -                               PreserveLCSSA))
>>> +      !UnrollRuntimeLoopRemainder(L, Count, AllowExpensiveTripCount,
>>> +                                  UnrollRuntimeEpilog, LI, SE, DT,
>>> +                                  PreserveLCSSA))
>>> return false;
>>> 
>>> // Notify ScalarEvolution that the loop will be substantially changed,
>>> 
>>> Modified: llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp (original)
>>> +++ llvm/trunk/lib/Transforms/Utils/LoopUnrollRuntime.cpp Tue Apr  5
>>> 07:19:35 2016
>>> @@ -16,8 +16,8 @@
>>> // case, we need to generate code to execute these 'left over' iterations.
>>> //
>>> // The current strategy generates an if-then-else sequence prior to the
>>> -// unrolled loop to execute the 'left over' iterations.  Other strategies
>>> -// include generate a loop before or after the unrolled loop.
>>> +// unrolled loop to execute the 'left over' iterations before or after the
>>> +// unrolled loop.
>>> //
>>> //===----------------------------------------------------------------------===//
>>> 
>>> @@ -60,33 +60,35 @@ STATISTIC(NumRuntimeUnrolled,
>>> ///   than the unroll factor.
>>> ///
>>> static void ConnectProlog(Loop *L, Value *BECount, unsigned Count,
>>> -                          BasicBlock *LastPrologBB, BasicBlock *PrologEnd,
>>> -                          BasicBlock *OrigPH, BasicBlock *NewPH,
>>> -                          ValueToValueMapTy &VMap, DominatorTree *DT,
>>> -                          LoopInfo *LI, bool PreserveLCSSA) {
>>> +                          BasicBlock *PrologExit, BasicBlock *PreHeader,
>>> +                          BasicBlock *NewPreHeader, ValueToValueMapTy
>>> &VMap,
>>> +                          DominatorTree *DT, LoopInfo *LI, bool
>>> PreserveLCSSA) {
>>> BasicBlock *Latch = L->getLoopLatch();
>>> assert(Latch && "Loop must have a latch");
>>> +  BasicBlock *PrologLatch = cast<BasicBlock>(VMap[Latch]);
>>> 
>>> // Create a PHI node for each outgoing value from the original loop
>>> // (which means it is an outgoing value from the prolog code too).
>>> // The new PHI node is inserted in the prolog end basic block.
>>> -  // The new PHI name is added as an operand of a PHI node in either
>>> +  // The new PHI node value is added as an operand of a PHI node in either
>>> // the loop header or the loop exit block.
>>> -  for (succ_iterator SBI = succ_begin(Latch), SBE = succ_end(Latch);
>>> -       SBI != SBE; ++SBI) {
>>> -    for (BasicBlock::iterator BBI = (*SBI)->begin();
>>> -         PHINode *PN = dyn_cast<PHINode>(BBI); ++BBI) {
>>> -
>>> +  for (BasicBlock *Succ : successors(Latch)) {
>>> +    for (Instruction &BBI : *Succ) {
>>> +      PHINode *PN = dyn_cast<PHINode>(&BBI);
>>> +      // Exit when we passed all PHI nodes.
>>> +      if (!PN)
>>> +        break;
>>>   // Add a new PHI node to the prolog end block and add the
>>>   // appropriate incoming values.
>>> -      PHINode *NewPN = PHINode::Create(PN->getType(), 2,
>>> PN->getName()+".unr",
>>> -                                       PrologEnd->getTerminator());
>>> +      PHINode *NewPN = PHINode::Create(PN->getType(), 2, PN->getName() +
>>> ".unr",
>>> +                                       PrologExit->getFirstNonPHI());
>>>   // Adding a value to the new PHI node from the original loop preheader.
>>>   // This is the value that skips all the prolog code.
>>>   if (L->contains(PN)) {
>>> -        NewPN->addIncoming(PN->getIncomingValueForBlock(NewPH), OrigPH);
>>> +        NewPN->addIncoming(PN->getIncomingValueForBlock(NewPreHeader),
>>> +                           PreHeader);
>>>   } else {
>>> -        NewPN->addIncoming(UndefValue::get(PN->getType()), OrigPH);
>>> +        NewPN->addIncoming(UndefValue::get(PN->getType()), PreHeader);
>>>   }
>>> 
>>>   Value *V = PN->getIncomingValueForBlock(Latch);
>>> @@ -97,22 +99,22 @@ static void ConnectProlog(Loop *L, Value
>>>   }
>>>   // Adding a value to the new PHI node from the last prolog block
>>>   // that was created.
>>> -      NewPN->addIncoming(V, LastPrologBB);
>>> +      NewPN->addIncoming(V, PrologLatch);
>>> 
>>>   // Update the existing PHI node operand with the value from the
>>>   // new PHI node.  How this is done depends on if the existing
>>>   // PHI node is in the original loop block, or the exit block.
>>>   if (L->contains(PN)) {
>>> -        PN->setIncomingValue(PN->getBasicBlockIndex(NewPH), NewPN);
>>> +        PN->setIncomingValue(PN->getBasicBlockIndex(NewPreHeader), NewPN);
>>>   } else {
>>> -        PN->addIncoming(NewPN, PrologEnd);
>>> +        PN->addIncoming(NewPN, PrologExit);
>>>   }
>>> }
>>> }
>>> 
>>> // Create a branch around the original loop, which is taken if there are no
>>> // iterations remaining to be executed after running the prologue.
>>> -  Instruction *InsertPt = PrologEnd->getTerminator();
>>> +  Instruction *InsertPt = PrologExit->getTerminator();
>>> IRBuilder<> B(InsertPt);
>>> 
>>> assert(Count != 0 && "nonsensical Count!");
>>> @@ -126,25 +128,152 @@ static void ConnectProlog(Loop *L, Value
>>> BasicBlock *Exit = L->getUniqueExitBlock();
>>> assert(Exit && "Loop must have a single exit block only");
>>> // Split the exit to maintain loop canonicalization guarantees
>>> -  SmallVector<BasicBlock*, 4> Preds(pred_begin(Exit), pred_end(Exit));
>>> +  SmallVector<BasicBlock*, 4> Preds(predecessors(Exit));
>>> SplitBlockPredecessors(Exit, Preds, ".unr-lcssa", DT, LI,
>>>                      PreserveLCSSA);
>>> // Add the branch to the exit block (around the unrolled loop)
>>> -  B.CreateCondBr(BrLoopExit, Exit, NewPH);
>>> +  B.CreateCondBr(BrLoopExit, Exit, NewPreHeader);
>>> +  InsertPt->eraseFromParent();
>>> +}
>>> +
>>> +/// Connect the unrolling epilog code to the original loop.
>>> +/// The unrolling epilog code contains code to execute the
>>> +/// 'extra' iterations if the run-time trip count modulo the
>>> +/// unroll count is non-zero.
>>> +///
>>> +/// This function performs the following:
>>> +/// - Update PHI nodes at the unrolling loop exit and epilog loop exit
>>> +/// - Create PHI nodes at the unrolling loop exit to combine
>>> +///   values that exit the unrolling loop code and jump around it.
>>> +/// - Update PHI operands in the epilog loop by the new PHI nodes
>>> +/// - Branch around the epilog loop if extra iters (ModVal) is zero.
>>> +///
>>> +static void ConnectEpilog(Loop *L, Value *ModVal, BasicBlock *NewExit,
>>> +                          BasicBlock *Exit, BasicBlock *PreHeader,
>>> +                          BasicBlock *EpilogPreHeader, BasicBlock
>>> *NewPreHeader,
>>> +                          ValueToValueMapTy &VMap, DominatorTree *DT,
>>> +                          LoopInfo *LI, bool PreserveLCSSA)  {
>>> +  BasicBlock *Latch = L->getLoopLatch();
>>> +  assert(Latch && "Loop must have a latch");
>>> +  BasicBlock *EpilogLatch = cast<BasicBlock>(VMap[Latch]);
>>> +
>>> +  // Loop structure should be the following:
>>> +  //
>>> +  // PreHeader
>>> +  // NewPreHeader
>>> +  //   Header
>>> +  //   ...
>>> +  //   Latch
>>> +  // NewExit (PN)
>>> +  // EpilogPreHeader
>>> +  //   EpilogHeader
>>> +  //   ...
>>> +  //   EpilogLatch
>>> +  // Exit (EpilogPN)
>>> +
>>> +  // Update PHI nodes at NewExit and Exit.
>>> +  for (Instruction &BBI : *NewExit) {
>>> +    PHINode *PN = dyn_cast<PHINode>(&BBI);
>>> +    // Exit when we passed all PHI nodes.
>>> +    if (!PN)
>>> +      break;
>>> +    // PN should be used in another PHI located in Exit block as
>>> +    // Exit was split by SplitBlockPredecessors into Exit and NewExit
>>> +    // Basicaly it should look like:
>>> +    // NewExit:
>>> +    //   PN = PHI [I, Latch]
>>> +    // ...
>>> +    // Exit:
>>> +    //   EpilogPN = PHI [PN, EpilogPreHeader]
>>> +    //
>>> +    // There is EpilogPreHeader incoming block instead of NewExit as
>>> +    // NewExit was spilt 1 more time to get EpilogPreHeader.
>>> +    assert(PN->hasOneUse() && "The phi should have 1 use");
>>> +    PHINode *EpilogPN = cast<PHINode> (PN->use_begin()->getUser());
>>> +    assert(EpilogPN->getParent() == Exit && "EpilogPN should be in Exit
>>> block");
>>> +
>>> +    // Add incoming PreHeader from branch around the Loop
>>> +    PN->addIncoming(UndefValue::get(PN->getType()), PreHeader);
>>> +
>>> +    Value *V = PN->getIncomingValueForBlock(Latch);
>>> +    Instruction *I = dyn_cast<Instruction>(V);
>>> +    if (I && L->contains(I))
>>> +      // If value comes from an instruction in the loop add VMap value.
>>> +      V = VMap[I];
>>> +    // For the instruction out of the loop, constant or undefined value
>>> +    // insert value itself.
>>> +    EpilogPN->addIncoming(V, EpilogLatch);
>>> +
>>> +    assert(EpilogPN->getBasicBlockIndex(EpilogPreHeader) >= 0 &&
>>> +          "EpilogPN should have EpilogPreHeader incoming block");
>>> +    // Change EpilogPreHeader incoming block to NewExit.
>>> +
>>> EpilogPN->setIncomingBlock(EpilogPN->getBasicBlockIndex(EpilogPreHeader),
>>> +                               NewExit);
>>> +    // Now PHIs should look like:
>>> +    // NewExit:
>>> +    //   PN = PHI [I, Latch], [undef, PreHeader]
>>> +    // ...
>>> +    // Exit:
>>> +    //   EpilogPN = PHI [PN, NewExit], [VMap[I], EpilogLatch]
>>> +  }
>>> +
>>> +  // Create PHI nodes at NewExit (from the unrolling loop Latch and
>>> PreHeader).
>>> +  // Update corresponding PHI nodes in epilog loop.
>>> +  for (BasicBlock *Succ : successors(Latch)) {
>>> +    // Skip this as we already updated phis in exit blocks.
>>> +    if (!L->contains(Succ))
>>> +      continue;
>>> +    for (Instruction &BBI : *Succ) {
>>> +      PHINode *PN = dyn_cast<PHINode>(&BBI);
>>> +      // Exit when we passed all PHI nodes.
>>> +      if (!PN)
>>> +        break;
>>> +      // Add new PHI nodes to the loop exit block and update epilog
>>> +      // PHIs with the new PHI values.
>>> +      PHINode *NewPN = PHINode::Create(PN->getType(), 2, PN->getName() +
>>> ".unr",
>>> +                                       NewExit->getFirstNonPHI());
>>> +      // Adding a value to the new PHI node from the unrolling loop
>>> preheader.
>>> +      NewPN->addIncoming(PN->getIncomingValueForBlock(NewPreHeader),
>>> PreHeader);
>>> +      // Adding a value to the new PHI node from the unrolling loop latch.
>>> +      NewPN->addIncoming(PN->getIncomingValueForBlock(Latch), Latch);
>>> +
>>> +      // Update the existing PHI node operand with the value from the new
>>> PHI
>>> +      // node.  Corresponding instruction in epilog loop should be PHI.
>>> +      PHINode *VPN = cast<PHINode>(VMap[&BBI]);
>>> +      VPN->setIncomingValue(VPN->getBasicBlockIndex(EpilogPreHeader),
>>> NewPN);
>>> +    }
>>> +  }
>>> +
>>> +  Instruction *InsertPt = NewExit->getTerminator();
>>> +  IRBuilder<> B(InsertPt);
>>> +  Value *BrLoopExit = B.CreateIsNotNull(ModVal);
>>> +  assert(Exit && "Loop must have a single exit block only");
>>> +  // Split the exit to maintain loop canonicalization guarantees
>>> +  SmallVector<BasicBlock*, 4> Preds(predecessors(Exit));
>>> +  SplitBlockPredecessors(Exit, Preds, ".epilog-lcssa", DT, LI,
>>> +                         PreserveLCSSA);
>>> +  // Add the branch to the exit block (around the unrolling loop)
>>> +  B.CreateCondBr(BrLoopExit, EpilogPreHeader, Exit);
>>> InsertPt->eraseFromParent();
>>> }
>>> 
>>> /// Create a clone of the blocks in a loop and connect them together.
>>> -/// If UnrollProlog is true, loop structure will not be cloned, otherwise a
>>> new
>>> -/// loop will be created including all cloned blocks, and the iterator of
>>> it
>>> -/// switches to count NewIter down to 0.
>>> +/// If CreateRemainderLoop is false, loop structure will not be cloned,
>>> +/// otherwise a new loop will be created including all cloned blocks, and
>>> the
>>> +/// iterator of it switches to count NewIter down to 0.
>>> +/// The cloned blocks should be inserted between InsertTop and InsertBot.
>>> +/// If loop structure is cloned InsertTop should be new preheader,
>>> InsertBot
>>> +/// new loop exit.
>>> ///
>>> -static void CloneLoopBlocks(Loop *L, Value *NewIter, const bool
>>> UnrollProlog,
>>> +static void CloneLoopBlocks(Loop *L, Value *NewIter,
>>> +                            const bool CreateRemainderLoop,
>>> +                            const bool UseEpilogRemainder,
>>>                         BasicBlock *InsertTop, BasicBlock *InsertBot,
>>> +                            BasicBlock *Preheader,
>>>                         std::vector<BasicBlock *> &NewBlocks,
>>>                         LoopBlocksDFS &LoopBlocks, ValueToValueMapTy
>>> &VMap,
>>>                         LoopInfo *LI) {
>>> -  BasicBlock *Preheader = L->getLoopPreheader();
>>> +  StringRef suffix = UseEpilogRemainder ? "epil" : "prol";
>>> BasicBlock *Header = L->getHeader();
>>> BasicBlock *Latch = L->getLoopLatch();
>>> Function *F = Header->getParent();
>>> @@ -152,7 +281,7 @@ static void CloneLoopBlocks(Loop *L, Val
>>> LoopBlocksDFS::RPOIterator BlockEnd = LoopBlocks.endRPO();
>>> Loop *NewLoop = nullptr;
>>> Loop *ParentLoop = L->getParentLoop();
>>> -  if (!UnrollProlog) {
>>> +  if (CreateRemainderLoop) {
>>> NewLoop = new Loop();
>>> if (ParentLoop)
>>>   ParentLoop->addChildLoop(NewLoop);
>>> @@ -163,7 +292,7 @@ static void CloneLoopBlocks(Loop *L, Val
>>> // For each block in the original loop, create a new copy,
>>> // and update the value map with the newly created values.
>>> for (LoopBlocksDFS::RPOIterator BB = BlockBegin; BB != BlockEnd; ++BB) {
>>> -    BasicBlock *NewBB = CloneBasicBlock(*BB, VMap, ".prol", F);
>>> +    BasicBlock *NewBB = CloneBasicBlock(*BB, VMap, "." + suffix, F);
>>> NewBlocks.push_back(NewBB);
>>> 
>>> if (NewLoop)
>>> @@ -179,16 +308,17 @@ static void CloneLoopBlocks(Loop *L, Val
>>> }
>>> 
>>> if (Latch == *BB) {
>>> -      // For the last block, if UnrollProlog is true, create a direct jump
>>> to
>>> -      // InsertBot. If not, create a loop back to cloned head.
>>> +      // For the last block, if CreateRemainderLoop is false, create a
>>> direct
>>> +      // jump to InsertBot. If not, create a loop back to cloned head.
>>>   VMap.erase((*BB)->getTerminator());
>>>   BasicBlock *FirstLoopBB = cast<BasicBlock>(VMap[Header]);
>>>   BranchInst *LatchBR = cast<BranchInst>(NewBB->getTerminator());
>>>   IRBuilder<> Builder(LatchBR);
>>> -      if (UnrollProlog) {
>>> +      if (!CreateRemainderLoop) {
>>>     Builder.CreateBr(InsertBot);
>>>   } else {
>>> -        PHINode *NewIdx = PHINode::Create(NewIter->getType(), 2,
>>> "prol.iter",
>>> +        PHINode *NewIdx = PHINode::Create(NewIter->getType(), 2,
>>> +                                          suffix + ".iter",
>>>                                       FirstLoopBB->getFirstNonPHI());
>>>     Value *IdxSub =
>>>         Builder.CreateSub(NewIdx, ConstantInt::get(NewIdx->getType(), 1),
>>> @@ -207,9 +337,15 @@ static void CloneLoopBlocks(Loop *L, Val
>>> // cloned loop.
>>> for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) {
>>> PHINode *NewPHI = cast<PHINode>(VMap[&*I]);
>>> -    if (UnrollProlog) {
>>> -      VMap[&*I] = NewPHI->getIncomingValueForBlock(Preheader);
>>> -      cast<BasicBlock>(VMap[Header])->getInstList().erase(NewPHI);
>>> +    if (!CreateRemainderLoop) {
>>> +      if (UseEpilogRemainder) {
>>> +        unsigned idx = NewPHI->getBasicBlockIndex(Preheader);
>>> +        NewPHI->setIncomingBlock(idx, InsertTop);
>>> +        NewPHI->removeIncomingValue(Latch, false);
>>> +      } else {
>>> +        VMap[&*I] = NewPHI->getIncomingValueForBlock(Preheader);
>>> +        cast<BasicBlock>(VMap[Header])->getInstList().erase(NewPHI);
>>> +      }
>>> } else {
>>>   unsigned idx = NewPHI->getBasicBlockIndex(Preheader);
>>>   NewPHI->setIncomingBlock(idx, InsertTop);
>>> @@ -254,7 +390,7 @@ static void CloneLoopBlocks(Loop *L, Val
>>> }
>>> }
>>> 
>>> -/// Insert code in the prolog code when unrolling a loop with a
>>> +/// Insert code in the prolog/epilog code when unrolling a loop with a
>>> /// run-time trip-count.
>>> ///
>>> /// This method assumes that the loop unroll factor is total number
>>> @@ -266,6 +402,7 @@ static void CloneLoopBlocks(Loop *L, Val
>>> /// instruction in SimplifyCFG.cpp.  Then, the backend decides how code for
>>> /// the switch instruction is generated.
>>> ///
>>> +/// ***Prolog case***
>>> ///        extraiters = tripcount % loopfactor
>>> ///        if (extraiters == 0) jump Loop:
>>> ///        else jump Prol
>>> @@ -277,17 +414,35 @@ static void CloneLoopBlocks(Loop *L, Val
>>> /// ...
>>> /// End:
>>> ///
>>> -bool llvm::UnrollRuntimeLoopProlog(Loop *L, unsigned Count,
>>> -                                   bool AllowExpensiveTripCount, LoopInfo
>>> *LI,
>>> -                                   ScalarEvolution *SE, DominatorTree *DT,
>>> -                                   bool PreserveLCSSA) {
>>> -  // For now, only unroll loops that contain a single exit.
>>> +/// ***Epilog case***
>>> +///        extraiters = tripcount % loopfactor
>>> +///        if (extraiters == tripcount) jump LoopExit:
>>> +///        unroll_iters = tripcount - extraiters
>>> +/// Loop:  LoopBody; (executes unroll_iter times);
>>> +///        unroll_iter -= 1
>>> +///        if (unroll_iter != 0) jump Loop:
>>> +/// LoopExit:
>>> +///        if (extraiters == 0) jump EpilExit:
>>> +/// Epil:  LoopBody; (executes extraiters times)
>>> +///        extraiters -= 1                 // Omitted if unroll factor is
>>> 2.
>>> +///        if (extraiters != 0) jump Epil: // Omitted if unroll factor is
>>> 2.
>>> +/// EpilExit:
>>> +
>>> +bool llvm::UnrollRuntimeLoopRemainder(Loop *L, unsigned Count,
>>> +                                      bool AllowExpensiveTripCount,
>>> +                                      bool UseEpilogRemainder,
>>> +                                      LoopInfo *LI, ScalarEvolution *SE,
>>> +                                      DominatorTree *DT, bool
>>> PreserveLCSSA) {
>>> +  // for now, only unroll loops that contain a single exit
>>> if (!L->getExitingBlock())
>>> return false;
>>> 
>>> // Make sure the loop is in canonical form, and there is a single
>>> // exit block only.
>>> -  if (!L->isLoopSimplifyForm() || !L->getUniqueExitBlock())
>>> +  if (!L->isLoopSimplifyForm())
>>> +    return false;
>>> +  BasicBlock *Exit = L->getUniqueExitBlock(); // successor out of loop
>>> +  if (!Exit)
>>> return false;
>>> 
>>> // Use Scalar Evolution to compute the trip count. This allows more loops to
>>> @@ -311,8 +466,8 @@ bool llvm::UnrollRuntimeLoopProlog(Loop
>>> return false;
>>> 
>>> BasicBlock *Header = L->getHeader();
>>> -  BasicBlock *PH = L->getLoopPreheader();
>>> -  BranchInst *PreHeaderBR = cast<BranchInst>(PH->getTerminator());
>>> +  BasicBlock *PreHeader = L->getLoopPreheader();
>>> +  BranchInst *PreHeaderBR = cast<BranchInst>(PreHeader->getTerminator());
>>> const DataLayout &DL = Header->getModule()->getDataLayout();
>>> SCEVExpander Expander(*SE, DL, "loop-unroll");
>>> if (!AllowExpensiveTripCount &&
>>> @@ -330,26 +485,75 @@ bool llvm::UnrollRuntimeLoopProlog(Loop
>>> SE->forgetLoop(ParentLoop);
>>> 
>>> BasicBlock *Latch = L->getLoopLatch();
>>> -  // It helps to split the original preheader twice, one for the end of the
>>> -  // prolog code and one for a new loop preheader.
>>> -  BasicBlock *PEnd = SplitEdge(PH, Header, DT, LI);
>>> -  BasicBlock *NewPH = SplitBlock(PEnd, PEnd->getTerminator(), DT, LI);
>>> -  PreHeaderBR = cast<BranchInst>(PH->getTerminator());
>>> 
>>> +  // Loop structure is the following:
>>> +  //
>>> +  // PreHeader
>>> +  //   Header
>>> +  //   ...
>>> +  //   Latch
>>> +  // Exit
>>> +
>>> +  BasicBlock *NewPreHeader;
>>> +  BasicBlock *NewExit = nullptr;
>>> +  BasicBlock *PrologExit = nullptr;
>>> +  BasicBlock *EpilogPreHeader = nullptr;
>>> +  BasicBlock *PrologPreHeader = nullptr;
>>> +
>>> +  if (UseEpilogRemainder) {
>>> +    // If epilog remainder
>>> +    // Split PreHeader to insert a branch around loop for unrolling.
>>> +    NewPreHeader = SplitBlock(PreHeader, PreHeader->getTerminator(), DT,
>>> LI);
>>> +    NewPreHeader->setName(PreHeader->getName() + ".new");
>>> +    // Split Exit to create phi nodes from branch above.
>>> +    SmallVector<BasicBlock*, 4> Preds(predecessors(Exit));
>>> +    NewExit = SplitBlockPredecessors(Exit, Preds, ".unr-lcssa",
>>> +                                     DT, LI, PreserveLCSSA);
>>> +    // Split NewExit to insert epilog remainder loop.
>>> +    EpilogPreHeader = SplitBlock(NewExit, NewExit->getTerminator(), DT,
>>> LI);
>>> +    EpilogPreHeader->setName(Header->getName() + ".epil.preheader");
>>> +  } else {
>>> +    // If prolog remainder
>>> +    // Split the original preheader twice to insert prolog remainder loop
>>> +    PrologPreHeader = SplitEdge(PreHeader, Header, DT, LI);
>>> +    PrologPreHeader->setName(Header->getName() + ".prol.preheader");
>>> +    PrologExit = SplitBlock(PrologPreHeader,
>>> PrologPreHeader->getTerminator(),
>>> +                            DT, LI);
>>> +    PrologExit->setName(Header->getName() + ".prol.loopexit");
>>> +    // Split PrologExit to get NewPreHeader.
>>> +    NewPreHeader = SplitBlock(PrologExit, PrologExit->getTerminator(), DT,
>>> LI);
>>> +    NewPreHeader->setName(PreHeader->getName() + ".new");
>>> +  }
>>> +  // Loop structure should be the following:
>>> +  //  Epilog             Prolog
>>> +  //
>>> +  // PreHeader         PreHeader
>>> +  // *NewPreHeader     *PrologPreHeader
>>> +  //   Header          *PrologExit
>>> +  //   ...             *NewPreHeader
>>> +  //   Latch             Header
>>> +  // *NewExit            ...
>>> +  // *EpilogPreHeader    Latch
>>> +  // Exit              Exit
>>> +
>>> +  // Calculate conditions for branch around loop for unrolling
>>> +  // in epilog case and around prolog remainder loop in prolog case.
>>> // Compute the number of extra iterations required, which is:
>>> -  //  extra iterations = run-time trip count % (loop unroll factor + 1)
>>> +  //  extra iterations = run-time trip count % loop unroll factor
>>> +  PreHeaderBR = cast<BranchInst>(PreHeader->getTerminator());
>>> Value *TripCount = Expander.expandCodeFor(TripCountSC,
>>> TripCountSC->getType(),
>>>                                         PreHeaderBR);
>>> Value *BECount = Expander.expandCodeFor(BECountSC, BECountSC->getType(),
>>>                                       PreHeaderBR);
>>> -
>>> IRBuilder<> B(PreHeaderBR);
>>> Value *ModVal;
>>> // Calculate ModVal = (BECount + 1) % Count.
>>> // Note that TripCount is BECount + 1.
>>> if (isPowerOf2_32(Count)) {
>>> +    // When Count is power of 2 we don't BECount for epilog case, however
>>> we'll
>>> +    // need it for a branch around unrolling loop for prolog case.
>>> ModVal = B.CreateAnd(TripCount, Count - 1, "xtraiter");
>>> -    //  1. There are no iterations to be run in the prologue loop.
>>> +    //  1. There are no iterations to be run in the prolog/epilog loop.
>>> // OR
>>> //  2. The addition computing TripCount overflowed.
>>> //
>>> @@ -371,18 +575,18 @@ bool llvm::UnrollRuntimeLoopProlog(Loop
>>>                       ConstantInt::get(BECount->getType(), Count),
>>>                       "xtraiter");
>>> }
>>> -  Value *BranchVal = B.CreateIsNotNull(ModVal, "lcmp.mod");
>>> -
>>> -  // Branch to either the extra iterations or the cloned/unrolled loop.
>>> -  // We will fix up the true branch label when adding loop body copies.
>>> -  B.CreateCondBr(BranchVal, PEnd, PEnd);
>>> -  assert(PreHeaderBR->isUnconditional() &&
>>> -         PreHeaderBR->getSuccessor(0) == PEnd &&
>>> -         "CFG edges in Preheader are not correct");
>>> +  Value *CmpOperand =
>>> +      UseEpilogRemainder ? TripCount :
>>> +                           ConstantInt::get(TripCount->getType(), 0);
>>> +  Value *BranchVal = B.CreateICmpNE(ModVal, CmpOperand, "lcmp.mod");
>>> +  BasicBlock *FirstLoop = UseEpilogRemainder ? NewPreHeader :
>>> PrologPreHeader;
>>> +  BasicBlock *SecondLoop = UseEpilogRemainder ? NewExit : PrologExit;
>>> +  // Branch to either remainder (extra iterations) loop or unrolling loop.
>>> +  B.CreateCondBr(BranchVal, FirstLoop, SecondLoop);
>>> PreHeaderBR->eraseFromParent();
>>> Function *F = Header->getParent();
>>> // Get an ordered list of blocks in the loop to help with the ordering of
>>> the
>>> -  // cloned blocks in the prolog code.
>>> +  // cloned blocks in the prolog/epilog code
>>> LoopBlocksDFS LoopBlocks(L);
>>> LoopBlocks.perform(LI);
>>> 
>>> @@ -394,17 +598,38 @@ bool llvm::UnrollRuntimeLoopProlog(Loop
>>> std::vector<BasicBlock *> NewBlocks;
>>> ValueToValueMapTy VMap;
>>> 
>>> -  bool UnrollPrologue = Count == 2;
>>> +  // For unroll factor 2 remainder loop will have 1 iterations.
>>> +  // Do not create 1 iteration loop.
>>> +  bool CreateRemainderLoop = (Count != 2);
>>> 
>>> // Clone all the basic blocks in the loop. If Count is 2, we don't clone
>>> // the loop, otherwise we create a cloned loop to execute the extra
>>> // iterations. This function adds the appropriate CFG connections.
>>> -  CloneLoopBlocks(L, ModVal, UnrollPrologue, PH, PEnd, NewBlocks,
>>> LoopBlocks,
>>> -                  VMap, LI);
>>> +  BasicBlock *InsertBot = UseEpilogRemainder ? Exit : PrologExit;
>>> +  BasicBlock *InsertTop = UseEpilogRemainder ? EpilogPreHeader :
>>> PrologPreHeader;
>>> +  CloneLoopBlocks(L, ModVal, CreateRemainderLoop, UseEpilogRemainder,
>>> InsertTop,
>>> +                  InsertBot, NewPreHeader, NewBlocks, LoopBlocks, VMap,
>>> LI);
>>> +
>>> +  // Insert the cloned blocks into the function.
>>> +  F->getBasicBlockList().splice(InsertBot->getIterator(),
>>> +                                F->getBasicBlockList(),
>>> +                                NewBlocks[0]->getIterator(),
>>> +                                F->end());
>>> 
>>> -  // Insert the cloned blocks into the function just before the original
>>> loop.
>>> -  F->getBasicBlockList().splice(PEnd->getIterator(),
>>> F->getBasicBlockList(),
>>> -                                NewBlocks[0]->getIterator(), F->end());
>>> +  // Loop structure should be the following:
>>> +  //  Epilog             Prolog
>>> +  //
>>> +  // PreHeader         PreHeader
>>> +  // NewPreHeader      PrologPreHeader
>>> +  //   Header            PrologHeader
>>> +  //   ...               ...
>>> +  //   Latch             PrologLatch
>>> +  // NewExit           PrologExit
>>> +  // EpilogPreHeader   NewPreHeader
>>> +  //   EpilogHeader      Header
>>> +  //   ...               ...
>>> +  //   EpilogLatch       Latch
>>> +  // Exit              Exit
>>> 
>>> // Rewrite the cloned instruction operands to use the values created when
>>> the
>>> // clone is created.
>>> @@ -415,11 +640,38 @@ bool llvm::UnrollRuntimeLoopProlog(Loop
>>> }
>>> }
>>> 
>>> -  // Connect the prolog code to the original loop and update the
>>> -  // PHI functions.
>>> -  BasicBlock *LastLoopBB = cast<BasicBlock>(VMap[Latch]);
>>> -  ConnectProlog(L, BECount, Count, LastLoopBB, PEnd, PH, NewPH, VMap, DT,
>>> LI,
>>> -                PreserveLCSSA);
>>> +  if (UseEpilogRemainder) {
>>> +    // Connect the epilog code to the original loop and update the
>>> +    // PHI functions.
>>> +    ConnectEpilog(L, ModVal, NewExit, Exit, PreHeader,
>>> +                  EpilogPreHeader, NewPreHeader, VMap, DT, LI,
>>> +                  PreserveLCSSA);
>>> +
>>> +    // Update counter in loop for unrolling.
>>> +    // I should be multiply of Count.
>>> +    IRBuilder<> B2(NewPreHeader->getTerminator());
>>> +    Value *TestVal = B2.CreateSub(TripCount, ModVal, "unroll_iter");
>>> +    BranchInst *LatchBR = cast<BranchInst>(Latch->getTerminator());
>>> +    B2.SetInsertPoint(LatchBR);
>>> +    PHINode *NewIdx = PHINode::Create(TestVal->getType(), 2, "niter",
>>> +                                      Header->getFirstNonPHI());
>>> +    Value *IdxSub =
>>> +        B2.CreateSub(NewIdx, ConstantInt::get(NewIdx->getType(), 1),
>>> +                     NewIdx->getName() + ".nsub");
>>> +    Value *IdxCmp;
>>> +    if (LatchBR->getSuccessor(0) == Header)
>>> +      IdxCmp = B2.CreateIsNotNull(IdxSub, NewIdx->getName() + ".ncmp");
>>> +    else
>>> +      IdxCmp = B2.CreateIsNull(IdxSub, NewIdx->getName() + ".ncmp");
>>> +    NewIdx->addIncoming(TestVal, NewPreHeader);
>>> +    NewIdx->addIncoming(IdxSub, Latch);
>>> +    LatchBR->setCondition(IdxCmp);
>>> +  } else {
>>> +    // Connect the prolog code to the original loop and update the
>>> +    // PHI functions.
>>> +    ConnectProlog(L, BECount, Count, PrologExit, PreHeader, NewPreHeader,
>>> +                  VMap, DT, LI, PreserveLCSSA);
>>> +  }
>>> NumRuntimeUnrolled++;
>>> return true;
>>> }
>>> 
>>> Modified: llvm/trunk/test/Transforms/LoopUnroll/AArch64/runtime-loop.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/AArch64/runtime-loop.ll?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LoopUnroll/AArch64/runtime-loop.ll (original)
>>> +++ llvm/trunk/test/Transforms/LoopUnroll/AArch64/runtime-loop.ll Tue Apr  5
>>> 07:19:35 2016
>>> @@ -1,13 +1,21 @@
>>> -; RUN: opt < %s -S -loop-unroll -mtriple aarch64 -mcpu=cortex-a57 |
>>> FileCheck %s
>>> +; RUN: opt < %s -S -loop-unroll -mtriple aarch64 -mcpu=cortex-a57 |
>>> FileCheck %s -check-prefix=EPILOG
>>> +; RUN: opt < %s -S -loop-unroll -mtriple aarch64 -mcpu=cortex-a57
>>> -unroll-runtime-epilog=false | FileCheck %s -check-prefix=PROLOG
>>> 
>>> ; Tests for unrolling loops with run-time trip counts
>>> 
>>> -; CHECK:  %xtraiter = and i32 %n
>>> -; CHECK:  %lcmp.mod = icmp ne i32 %xtraiter, 0
>>> -; CHECK:  br i1 %lcmp.mod, label %for.body.prol, label
>>> %for.body.preheader.split
>>> +; EPILOG:  %xtraiter = and i32 %n
>>> +; EPILOG:  %lcmp.mod = icmp ne i32 %xtraiter, %n
>>> +; EPILOG:  br i1 %lcmp.mod, label %for.body.preheader.new, label
>>> %for.end.loopexit.unr-lcssa
>>> 
>>> -; CHECK:  for.body.prol:
>>> -; CHECK:  for.body:
>>> +; PROLOG:  %xtraiter = and i32 %n
>>> +; PROLOG:  %lcmp.mod = icmp ne i32 %xtraiter, 0
>>> +; PROLOG:  br i1 %lcmp.mod, label %for.body.prol.preheader, label
>>> %for.body.prol.loopexit
>>> +
>>> +; EPILOG:  for.body:
>>> +; EPILOG:  for.body.epil:
>>> +
>>> +; PROLOG:  for.body.prol:
>>> +; PROLOG:  for.body:
>>> 
>>> define i32 @test(i32* nocapture %a, i32 %n) nounwind uwtable readonly {
>>> entry:
>>> 
>>> Modified: llvm/trunk/test/Transforms/LoopUnroll/PowerPC/a2-unrolling.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/PowerPC/a2-unrolling.ll?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LoopUnroll/PowerPC/a2-unrolling.ll (original)
>>> +++ llvm/trunk/test/Transforms/LoopUnroll/PowerPC/a2-unrolling.ll Tue Apr  5
>>> 07:19:35 2016
>>> @@ -1,4 +1,5 @@
>>> -; RUN: opt < %s -S -mtriple=powerpc64-unknown-linux-gnu -mcpu=a2
>>> -loop-unroll | FileCheck %s
>>> +; RUN: opt < %s -S -mtriple=powerpc64-unknown-linux-gnu -mcpu=a2
>>> -loop-unroll | FileCheck %s -check-prefix=EPILOG
>>> +; RUN: opt < %s -S -mtriple=powerpc64-unknown-linux-gnu -mcpu=a2
>>> -loop-unroll -unroll-runtime-epilog=false | FileCheck %s
>>> -check-prefix=PROLOG
>>> define void @unroll_opt_for_size() nounwind optsize {
>>> entry:
>>> br label %loop
>>> @@ -13,11 +14,17 @@ exit:
>>> ret void
>>> }
>>> 
>>> -; CHECK-LABEL: @unroll_opt_for_size
>>> -; CHECK:      add
>>> -; CHECK-NEXT: add
>>> -; CHECK-NEXT: add
>>> -; CHECK: icmp
>>> +; EPILOG-LABEL: @unroll_opt_for_size
>>> +; EPILOG:      add
>>> +; EPILOG-NEXT: add
>>> +; EPILOG-NEXT: add
>>> +; EPILOG: icmp
>>> +
>>> +; PROLOG-LABEL: @unroll_opt_for_size
>>> +; PROLOG:      add
>>> +; PROLOG-NEXT: add
>>> +; PROLOG-NEXT: add
>>> +; PROLOG: icmp
>>> 
>>> define i32 @test(i32* nocapture %a, i32 %n) nounwind uwtable readonly {
>>> entry:
>>> @@ -40,8 +47,13 @@ for.end:
>>> ret i32 %sum.0.lcssa
>>> }
>>> 
>>> -; CHECK-LABEL: @test
>>> -; CHECK: for.body.prol{{.*}}:
>>> -; CHECK: for.body:
>>> -; CHECK: br i1 %exitcond.7, label %for.end.loopexit{{.*}}, label %for.body
>>> +; EPILOG-LABEL: @test
>>> +; EPILOG: for.body:
>>> +; EPILOG: br i1 %niter.ncmp.7, label %for.end.loopexit{{.*}}, label
>>> %for.body
>>> +; EPILOG: for.body.epil{{.*}}:
>>> +
>>> +; PROLOG-LABEL: @test
>>> +; PROLOG: for.body.prol{{.*}}:
>>> +; PROLOG: for.body:
>>> +; PROLOG: br i1 %exitcond.7, label %for.end.loopexit{{.*}}, label %for.body
>>> 
>>> 
>>> Modified: llvm/trunk/test/Transforms/LoopUnroll/X86/mmx.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/X86/mmx.ll?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LoopUnroll/X86/mmx.ll (original)
>>> +++ llvm/trunk/test/Transforms/LoopUnroll/X86/mmx.ll Tue Apr  5 07:19:35
>>> 2016
>>> @@ -14,9 +14,9 @@ for.body:
>>> 
>>> exit:                                             ; preds = %for.body
>>> %ret = phi x86_mmx [ undef, %for.body ]
>>> -  ; CHECK: %[[ret_unr:.*]] = phi x86_mmx [ undef,
>>> -  ; CHECK: %[[ret_ph:.*]]  = phi x86_mmx [ undef,
>>> -  ; CHECK: %[[ret:.*]] = phi x86_mmx [ %[[ret_unr]], {{.*}} ], [
>>> %[[ret_ph]]
>>> +  ; CHECK: %[[ret_ph:.*]] = phi x86_mmx [ undef, %entry
>>> +  ; CHECK: %[[ret_ph1:.*]]  = phi x86_mmx [ undef,
>>> +  ; CHECK: %[[ret:.*]] = phi x86_mmx [ %[[ret_ph]], {{.*}} ], [
>>> %[[ret_ph1]],
>>> ; CHECK: ret x86_mmx %[[ret]]
>>> ret x86_mmx %ret
>>> }
>>> 
>>> Modified:
>>> llvm/trunk/test/Transforms/LoopUnroll/high-cost-trip-count-computation.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/high-cost-trip-count-computation.ll?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> ---
>>> llvm/trunk/test/Transforms/LoopUnroll/high-cost-trip-count-computation.ll
>>> (original)
>>> +++
>>> llvm/trunk/test/Transforms/LoopUnroll/high-cost-trip-count-computation.ll
>>> Tue Apr  5 07:19:35 2016
>>> @@ -34,7 +34,7 @@ define i32 @test2(i64* %loc, i64 %conv7)
>>> ; CHECK: udiv
>>> ; CHECK: udiv
>>> ; CHECK-NOT: udiv
>>> -; CHECK-LABEL: for.body.prol
>>> +; CHECK-LABEL: for.body
>>> entry:
>>> %rem0 = load i64, i64* %loc, align 8
>>> %ExpensiveComputation = udiv i64 %rem0, 42 ; <<< Extra computations are
>>> added to the trip-count expression
>>> 
>>> Modified: llvm/trunk/test/Transforms/LoopUnroll/runtime-loop.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/runtime-loop.ll?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LoopUnroll/runtime-loop.ll (original)
>>> +++ llvm/trunk/test/Transforms/LoopUnroll/runtime-loop.ll Tue Apr  5
>>> 07:19:35 2016
>>> @@ -1,18 +1,30 @@
>>> -; RUN: opt < %s -S -loop-unroll -unroll-runtime=true | FileCheck %s
>>> +; RUN: opt < %s -S -loop-unroll -unroll-runtime=true | FileCheck %s
>>> -check-prefix=EPILOG
>>> +; RUN: opt < %s -S -loop-unroll -unroll-runtime=true
>>> -unroll-runtime-epilog=false | FileCheck %s -check-prefix=PROLOG
>>> 
>>> target datalayout =
>>> "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
>>> 
>>> ; Tests for unrolling loops with run-time trip counts
>>> 
>>> -; CHECK: %xtraiter = and i32 %n
>>> -; CHECK:  %lcmp.mod = icmp ne i32 %xtraiter, 0
>>> -; CHECK:  br i1 %lcmp.mod, label %for.body.prol, label
>>> %for.body.preheader.split
>>> -
>>> -; CHECK: for.body.prol:
>>> -; CHECK: %indvars.iv.prol = phi i64 [ %indvars.iv.next.prol, %for.body.prol
>>> ], [ 0, %for.body.preheader ]
>>> -; CHECK:  %prol.iter.sub = sub i32 %prol.iter, 1
>>> -; CHECK:  %prol.iter.cmp = icmp ne i32 %prol.iter.sub, 0
>>> -; CHECK:  br i1 %prol.iter.cmp, label %for.body.prol, label
>>> %for.body.preheader.split, !llvm.loop !0
>>> +; EPILOG: %xtraiter = and i32 %n
>>> +; EPILOG:  %lcmp.mod = icmp ne i32 %xtraiter, %n
>>> +; EPILOG:  br i1 %lcmp.mod, label %for.body.preheader.new, label
>>> %for.end.loopexit.unr-lcssa
>>> +
>>> +; PROLOG: %xtraiter = and i32 %n
>>> +; PROLOG:  %lcmp.mod = icmp ne i32 %xtraiter, 0
>>> +; PROLOG:  br i1 %lcmp.mod, label %for.body.prol.preheader, label
>>> %for.body.prol.loopexit
>>> +
>>> +; EPILOG: for.body.epil:
>>> +; EPILOG: %indvars.iv.epil = phi i64 [ %indvars.iv.next.epil,
>>> %for.body.epil ],  [ %indvars.iv.unr, %for.body.epil.preheader ]
>>> +; EPILOG:  %epil.iter.sub = sub i32 %epil.iter, 1
>>> +; EPILOG:  %epil.iter.cmp = icmp ne i32 %epil.iter.sub, 0
>>> +; EPILOG:  br i1 %epil.iter.cmp, label %for.body.epil, label
>>> %for.end.loopexit.epilog-lcssa, !llvm.loop !0
>>> +
>>> +; PROLOG: for.body.prol:
>>> +; PROLOG: %indvars.iv.prol = phi i64 [ %indvars.iv.next.prol,
>>> %for.body.prol ], [ 0, %for.body.prol.preheader ]
>>> +; PROLOG:  %prol.iter.sub = sub i32 %prol.iter, 1
>>> +; PROLOG:  %prol.iter.cmp = icmp ne i32 %prol.iter.sub, 0
>>> +; PROLOG:  br i1 %prol.iter.cmp, label %for.body.prol, label
>>> %for.body.prol.loopexit, !llvm.loop !0
>>> +
>>> 
>>> define i32 @test(i32* nocapture %a, i32 %n) nounwind uwtable readonly {
>>> entry:
>>> @@ -39,8 +51,11 @@ for.end:
>>> ; Still try to completely unroll loops with compile-time trip counts
>>> ; even if the -unroll-runtime is specified
>>> 
>>> -; CHECK: for.body:
>>> -; CHECK-NOT: for.body.prol:
>>> +; EPILOG: for.body:
>>> +; EPILOG-NOT: for.body.epil:
>>> +
>>> +; PROLOG: for.body:
>>> +; PROLOG-NOT: for.body.prol:
>>> 
>>> define i32 @test1(i32* nocapture %a) nounwind uwtable readonly {
>>> entry:
>>> @@ -64,7 +79,8 @@ for.end:
>>> ; This is test 2007-05-09-UnknownTripCount.ll which can be unrolled now
>>> ; if the -unroll-runtime option is turned on
>>> 
>>> -; CHECK: bb72.2:
>>> +; EPILOG: bb72.2:
>>> +; PROLOG: bb72.2:
>>> 
>>> define void @foo(i32 %trips) {
>>> entry:
>>> @@ -86,8 +102,11 @@ cond_true138:
>>> 
>>> ; Test run-time unrolling for a loop that counts down by -2.
>>> 
>>> -; CHECK: for.body.prol:
>>> -; CHECK: br i1 %prol.iter.cmp, label %for.body.prol, label
>>> %for.body.preheader.split
>>> +; EPILOG: for.body.epil:
>>> +; EPILOG: br i1 %epil.iter.cmp, label %for.body.epil, label
>>> %for.cond.for.end_crit_edge.epilog-lcssa
>>> +
>>> +; PROLOG: for.body.prol:
>>> +; PROLOG: br i1 %prol.iter.cmp, label %for.body.prol, label
>>> %for.body.prol.loopexit
>>> 
>>> define zeroext i16 @down(i16* nocapture %p, i32 %len) nounwind uwtable
>>> readonly {
>>> entry:
>>> @@ -116,8 +135,11 @@ for.end:
>>> }
>>> 
>>> ; Test run-time unrolling disable metadata.
>>> -; CHECK: for.body:
>>> -; CHECK-NOT: for.body.prol:
>>> +; EPILOG: for.body:
>>> +; EPILOG-NOT: for.body.epil:
>>> +
>>> +; PROLOG: for.body:
>>> +; PROLOG-NOT: for.body.prol:
>>> 
>>> define zeroext i16 @test2(i16* nocapture %p, i32 %len) nounwind uwtable
>>> readonly {
>>> entry:
>>> @@ -148,6 +170,8 @@ for.end:
>>> !0 = distinct !{!0, !1}
>>> !1 = !{!"llvm.loop.unroll.runtime.disable"}
>>> 
>>> -; CHECK: !0 = distinct !{!0, !1}
>>> -; CHECK: !1 = !{!"llvm.loop.unroll.disable"}
>>> +; EPILOG: !0 = distinct !{!0, !1}
>>> +; EPILOG: !1 = !{!"llvm.loop.unroll.disable"}
>>> 
>>> +; PROLOG: !0 = distinct !{!0, !1}
>>> +; PROLOG: !1 = !{!"llvm.loop.unroll.disable"}
>>> 
>>> Modified: llvm/trunk/test/Transforms/LoopUnroll/runtime-loop1.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/runtime-loop1.ll?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LoopUnroll/runtime-loop1.ll (original)
>>> +++ llvm/trunk/test/Transforms/LoopUnroll/runtime-loop1.ll Tue Apr  5
>>> 07:19:35 2016
>>> @@ -1,19 +1,35 @@
>>> -; RUN: opt < %s -S -loop-unroll -unroll-runtime -unroll-count=2 | FileCheck
>>> %s
>>> +; RUN: opt < %s -S -loop-unroll -unroll-runtime -unroll-count=2 | FileCheck
>>> %s -check-prefix=EPILOG
>>> +; RUN: opt < %s -S -loop-unroll -unroll-runtime -unroll-count=2
>>> -unroll-runtime-epilog=false | FileCheck %s -check-prefix=PROLOG
>>> 
>>> ; This tests that setting the unroll count works
>>> 
>>> -; CHECK: for.body.preheader:
>>> -; CHECK:   br {{.*}} label %for.body.prol, label %for.body.preheader.split,
>>> !dbg [[PH_LOC:![0-9]+]]
>>> -; CHECK: for.body.prol:
>>> -; CHECK:   br label %for.body.preheader.split, !dbg [[BODY_LOC:![0-9]+]]
>>> -; CHECK: for.body.preheader.split:
>>> -; CHECK:   br {{.*}} label %for.end.loopexit, label
>>> %for.body.preheader.split.split, !dbg [[PH_LOC]]
>>> -; CHECK: for.body:
>>> -; CHECK:   br i1 %exitcond.1, label %for.end.loopexit.unr-lcssa, label
>>> %for.body, !dbg [[BODY_LOC]]
>>> -; CHECK-NOT: br i1 %exitcond.4, label %for.end.loopexit{{.*}}, label
>>> %for.body
>>> 
>>> -; CHECK-DAG: [[PH_LOC]] = !DILocation(line: 101, column: 1, scope: !{{.*}})
>>> -; CHECK-DAG: [[BODY_LOC]] = !DILocation(line: 102, column: 1, scope:
>>> !{{.*}})
>>> +; EPILOG: for.body.preheader:
>>> +; EPILOG:   br i1 %lcmp.mod, label %for.body.preheader.new, label
>>> %for.end.loopexit.unr-lcssa, !dbg [[PH_LOC:![0-9]+]]
>>> +; EPILOG: for.body:
>>> +; EPILOG:   br i1 %niter.ncmp.1, label
>>> %for.end.loopexit.unr-lcssa.loopexit, label %for.body, !dbg
>>> [[BODY_LOC:![0-9]+]]
>>> +; EPILOG-NOT: br i1 %niter.ncmp.2, label %for.end.loopexit{{.*}}, label
>>> %for.body
>>> +; EPILOG: for.body.epil.preheader:
>>> +; EPILOG:   br label %for.body.epil, !dbg [[EXIT_LOC:![0-9]+]]
>>> +; EPILOG: for.body.epil:
>>> +; EPILOG:   br label %for.end.loopexit.epilog-lcssa, !dbg
>>> [[BODY_LOC:![0-9]+]]
>>> +
>>> +; EPILOG-DAG: [[PH_LOC]] = !DILocation(line: 101, column: 1, scope:
>>> !{{.*}})
>>> +; EPILOG-DAG: [[BODY_LOC]] = !DILocation(line: 102, column: 1, scope:
>>> !{{.*}})
>>> +; EPILOG-DAG: [[EXIT_LOC]] = !DILocation(line: 103, column: 1, scope:
>>> !{{.*}})
>>> +
>>> +; PROLOG: for.body.preheader:
>>> +; PROLOG:   br {{.*}} label %for.body.prol.preheader, label
>>> %for.body.prol.loopexit, !dbg [[PH_LOC:![0-9]+]]
>>> +; PROLOG: for.body.prol:
>>> +; PROLOG:   br label %for.body.prol.loopexit, !dbg [[BODY_LOC:![0-9]+]]
>>> +; PROLOG: for.body.prol.loopexit:
>>> +; PROLOG:   br {{.*}} label %for.end.loopexit, label
>>> %for.body.preheader.new, !dbg [[PH_LOC]]
>>> +; PROLOG: for.body:
>>> +; PROLOG:   br i1 %exitcond.1, label %for.end.loopexit.unr-lcssa, label
>>> %for.body, !dbg [[BODY_LOC]]
>>> +; PROLOG-NOT: br i1 %exitcond.4, label %for.end.loopexit{{.*}}, label
>>> %for.body
>>> +
>>> +; PROLOG-DAG: [[PH_LOC]] = !DILocation(line: 101, column: 1, scope:
>>> !{{.*}})
>>> +; PROLOG-DAG: [[BODY_LOC]] = !DILocation(line: 102, column: 1, scope:
>>> !{{.*}})
>>> 
>>> define i32 @test(i32* nocapture %a, i32 %n) nounwind uwtable readonly !dbg
>>> !6 {
>>> entry:
>>> 
>>> Modified: llvm/trunk/test/Transforms/LoopUnroll/runtime-loop2.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/runtime-loop2.ll?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LoopUnroll/runtime-loop2.ll (original)
>>> +++ llvm/trunk/test/Transforms/LoopUnroll/runtime-loop2.ll Tue Apr  5
>>> 07:19:35 2016
>>> @@ -1,12 +1,18 @@
>>> -; RUN: opt < %s -S -loop-unroll -unroll-threshold=25 -unroll-runtime
>>> -unroll-count=8 | FileCheck %s
>>> +; RUN: opt < %s -S -loop-unroll -unroll-threshold=25 -unroll-runtime
>>> -unroll-count=8 | FileCheck %s  -check-prefix=EPILOG
>>> +; RUN: opt < %s -S -loop-unroll -unroll-threshold=25 -unroll-runtime
>>> -unroll-runtime-epilog=false | FileCheck %s -check-prefix=PROLOG
>>> 
>>> ; Choose a smaller, power-of-two, unroll count if the loop is too large.
>>> ; This test makes sure we're not unrolling 'odd' counts
>>> 
>>> -; CHECK: for.body.prol:
>>> -; CHECK: for.body:
>>> -; CHECK: br i1 %exitcond.3, label %for.end.loopexit{{.*}}, label %for.body
>>> -; CHECK-NOT: br i1 %exitcond.4, label %for.end.loopexit{{.*}}, label
>>> %for.body
>>> +; EPILOG: for.body:
>>> +; EPILOG: br i1 %niter.ncmp.3, label
>>> %for.end.loopexit.unr-lcssa.loopexit{{.*}}, label %for.body
>>> +; EPILOG-NOT: br i1 %niter.ncmp.4, label
>>> %for.end.loopexit.unr-lcssa.loopexit{{.*}}, label %for.body
>>> +; EPILOG: for.body.epil:
>>> +
>>> +; PROLOG: for.body.prol:
>>> +; PROLOG: for.body:
>>> +; PROLOG: br i1 %exitcond.3, label %for.end.loopexit{{.*}}, label %for.body
>>> +; PROLOG-NOT: br i1 %exitcond.4, label %for.end.loopexit{{.*}}, label
>>> %for.body
>>> 
>>> define i32 @test(i32* nocapture %a, i32 %n) nounwind uwtable readonly {
>>> entry:
>>> 
>>> Modified: llvm/trunk/test/Transforms/LoopUnroll/runtime-loop4.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/runtime-loop4.ll?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LoopUnroll/runtime-loop4.ll (original)
>>> +++ llvm/trunk/test/Transforms/LoopUnroll/runtime-loop4.ll Tue Apr  5
>>> 07:19:35 2016
>>> @@ -1,13 +1,21 @@
>>> -; RUN: opt < %s -S -O2 -unroll-runtime=true | FileCheck %s
>>> +; RUN: opt < %s -S -O2 -unroll-runtime=true | FileCheck %s
>>> -check-prefix=EPILOG
>>> +; RUN: opt < %s -S -O2 -unroll-runtime=true -unroll-runtime-epilog=false |
>>> FileCheck %s -check-prefix=PROLOG
>>> 
>>> ; Check runtime unrolling prologue can be promoted by LICM pass.
>>> 
>>> -; CHECK: entry:
>>> -; CHECK: %xtraiter
>>> -; CHECK: %lcmp.mod
>>> -; CHECK: loop1:
>>> -; CHECK: br i1 %lcmp.mod
>>> -; CHECK: loop2.prol:
>>> +; EPILOG: entry:
>>> +; EPILOG: %xtraiter
>>> +; EPILOG: %lcmp.mod
>>> +; EPILOG: loop1:
>>> +; EPILOG: br i1 %lcmp.mod
>>> +; EPILOG: loop2.epil:
>>> +
>>> +; PROLOG: entry:
>>> +; PROLOG: %xtraiter
>>> +; PROLOG: %lcmp.mod
>>> +; PROLOG: loop1:
>>> +; PROLOG: br i1 %lcmp.mod
>>> +; PROLOG: loop2.prol:
>>> 
>>> define void @unroll(i32 %iter, i32* %addr1, i32* %addr2) nounwind {
>>> entry:
>>> 
>>> Modified: llvm/trunk/test/Transforms/LoopUnroll/runtime-loop5.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/runtime-loop5.ll?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LoopUnroll/runtime-loop5.ll (original)
>>> +++ llvm/trunk/test/Transforms/LoopUnroll/runtime-loop5.ll Tue Apr  5
>>> 07:19:35 2016
>>> @@ -11,9 +11,6 @@ entry:
>>> %cmp1 = icmp eq i3 %n, 0
>>> br i1 %cmp1, label %for.end, label %for.body
>>> 
>>> -; UNROLL-16-NOT: for.body.prol:
>>> -; UNROLL-4: for.body.prol:
>>> -
>>> for.body:                                         ; preds = %for.body,
>>> %entry
>>> ; UNROLL-16-LABEL: for.body:
>>> ; UNROLL-4-LABEL: for.body:
>>> @@ -39,6 +36,10 @@ for.body:
>>> 
>>> ; UNROLL-16-LABEL: for.end
>>> ; UNROLL-4-LABEL: for.end
>>> +
>>> +; UNROLL-16-NOT: for.body.epil:
>>> +; UNROLL-4: for.body.epil:
>>> +
>>> for.end:                                          ; preds = %for.body,
>>> %entry
>>> %sum.0.lcssa = phi i3 [ 0, %entry ], [ %add, %for.body ]
>>> ret i3 %sum.0.lcssa
>>> 
>>> Modified: llvm/trunk/test/Transforms/LoopUnroll/tripcount-overflow.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/tripcount-overflow.ll?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LoopUnroll/tripcount-overflow.ll (original)
>>> +++ llvm/trunk/test/Transforms/LoopUnroll/tripcount-overflow.ll Tue Apr  5
>>> 07:19:35 2016
>>> @@ -13,13 +13,13 @@ target datalayout = "e-m:o-i64:64-f80:12
>>> ; CHECK: entry:
>>> ; CHECK-NEXT: %0 = add i32 %N, 1
>>> ; CHECK-NEXT: %xtraiter = and i32 %0, 1
>>> -; CHECK-NEXT: %lcmp.mod = icmp ne i32 %xtraiter, 0
>>> -; CHECK-NEXT: br i1 %lcmp.mod, label %while.body.prol, label %entry.split
>>> +; CHECK-NEXT: %lcmp.mod = icmp ne i32 %xtraiter, %0
>>> +; CHECK-NEXT: br i1 %lcmp.mod, label %entry.new, label %while.end.unr-lcssa
>>> 
>>> -; CHECK: while.body.prol:
>>> -; CHECK: br label %entry.split
>>> +; CHECK: while.body.epil:
>>> +; CHECK: br label %while.end.epilog-lcssa
>>> 
>>> -; CHECK: entry.split:
>>> +; CHECK: while.end.epilog-lcssa:
>>> 
>>> ; Function Attrs: nounwind readnone ssp uwtable
>>> define i32 @foo(i32 %N) {
>>> 
>>> Modified: llvm/trunk/test/Transforms/LoopUnroll/unroll-cleanup.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/unroll-cleanup.ll?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LoopUnroll/unroll-cleanup.ll (original)
>>> +++ llvm/trunk/test/Transforms/LoopUnroll/unroll-cleanup.ll Tue Apr  5
>>> 07:19:35 2016
>>> @@ -4,14 +4,14 @@
>>> ; RUN: opt < %s -O2 -S | FileCheck %s
>>> 
>>> ; After loop unroll:
>>> -;       %dec18 = add nsw i32 %dec18.in, -1
>>> +;       %niter.nsub = add nsw i32 %niter, -1
>>> ;       ...
>>> -;       %dec18.1 = add nsw i32 %dec18, -1
>>> +;       %niter.nsub.1 = add nsw i32 %niter.nsub, -1
>>> ; should be merged to:
>>> -;       %dec18.1 = add nsw i32 %dec18.in, -2
>>> +;       %dec18.1 = add nsw i32 %niter, -2
>>> ;
>>> ; CHECK-LABEL: @_Z3fn1v(
>>> -; CHECK: %dec18.1 = add nsw i32 %dec18.in, -2
>>> +; CHECK: %niter.nsub.1 = add i32 %niter, -2
>>> 
>>> ; ModuleID = '<stdin>'
>>> target triple = "x86_64-unknown-linux-gnu"
>>> 
>>> Modified: llvm/trunk/test/Transforms/LoopUnroll/unroll-pragmas.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/unroll-pragmas.ll?rev=265388&r1=265387&r2=265388&view=diff
>>> ==============================================================================
>>> --- llvm/trunk/test/Transforms/LoopUnroll/unroll-pragmas.ll (original)
>>> +++ llvm/trunk/test/Transforms/LoopUnroll/unroll-pragmas.ll Tue Apr  5
>>> 07:19:35 2016
>>> @@ -171,10 +171,6 @@ for.end:
>>> ; should be duplicated (original and 4x unrolled).
>>> ;
>>> ; CHECK-LABEL: @runtime_loop_with_count4(
>>> -; CHECK: for.body.prol:
>>> -; CHECK: store
>>> -; CHECK-NOT: store
>>> -; CHECK: br i1
>>> ; CHECK: for.body
>>> ; CHECK: store
>>> ; CHECK: store
>>> @@ -182,6 +178,10 @@ for.end:
>>> ; CHECK: store
>>> ; CHECK-NOT: store
>>> ; CHECK: br i1
>>> +; CHECK: for.body.epil:
>>> +; CHECK: store
>>> +; CHECK-NOT: store
>>> +; CHECK: br i1
>>> define void @runtime_loop_with_count4(i32* nocapture %a, i32 %b) {
>>> entry:
>>> %cmp3 = icmp sgt i32 %b, 0
>>> @@ -287,10 +287,6 @@ for.end:
>>> ; (original and 8x).
>>> ;
>>> ; CHECK-LABEL: @runtime_loop_with_enable(
>>> -; CHECK: for.body.prol:
>>> -; CHECK: store
>>> -; CHECK-NOT: store
>>> -; CHECK: br i1
>>> ; CHECK: for.body:
>>> ; CHECK: store i32
>>> ; CHECK: store i32
>>> @@ -302,6 +298,10 @@ for.end:
>>> ; CHECK: store i32
>>> ; CHECK-NOT: store i32
>>> ; CHECK: br i1
>>> +; CHECK: for.body.epil:
>>> +; CHECK: store
>>> +; CHECK-NOT: store
>>> +; CHECK: br i1
>>> define void @runtime_loop_with_enable(i32* nocapture %a, i32 %b) {
>>> entry:
>>> %cmp3 = icmp sgt i32 %b, 0
>>> @@ -328,16 +328,16 @@ for.end:
>>> ; should be duplicated (original and 3x unrolled).
>>> ;
>>> ; CHECK-LABEL: @runtime_loop_with_count3(
>>> -; CHECK: for.body.prol:
>>> -; CHECK: store
>>> -; CHECK-NOT: store
>>> -; CHECK: br i1
>>> ; CHECK: for.body
>>> ; CHECK: store
>>> ; CHECK: store
>>> ; CHECK: store
>>> ; CHECK-NOT: store
>>> ; CHECK: br i1
>>> +; CHECK: for.body.epil:
>>> +; CHECK: store
>>> +; CHECK-NOT: store
>>> +; CHECK: br i1
>>> define void @runtime_loop_with_count3(i32* nocapture %a, i32 %b) {
>>> entry:
>>> %cmp3 = icmp sgt i32 %b, 0
>>> 
>>> 
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>>> 
>>> 
>>> _______________________________________________
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