[SLPVectorizer] Schedule bundle with different opcodes.

[dtemirbulatov]

Summary

This change is part of https://reviews.llvm.org/D28907.

Following change let us schedule a bundle with different opcodes in it, for example : [ load, add, add, add ]

[RKSimon]

Test cases?

lib/Transforms/Vectorize/SLPVectorizer.cpp

970 ↗

(On Diff #110379)

You can avoid the extra indentation by an early-out

if (BundleMember->Inst != BundleMember->OpValue) {
  BundleMember = BundleMember->NextInBundle;
  continue;
}

You might even be able to tidily replace the while loop with a for loop it you used shorter variable names.

3439 ↗

(On Diff #110379)

early-out:

ScheduleData *ISD = getScheduleData(I);
if (!ISD)
  return false;

you can then remove that (void)ISD;

3459 ↗

(On Diff #110379)

weird indentation - clang-format ?

3482 ↗

(On Diff #110379)

weird indentation - clang-format ?

3494 ↗

(On Diff #110379)

weird indentation - clang-format ?

3570 ↗

(On Diff #110379)

Comments! You used "Handle def-use chain dependencies." for both cases!

[dtemirbulatov]

lib/Transforms/Vectorize/SLPVectorizer.cpp

970 ↗

(On Diff #110379)

Correct, Thanks.

3439 ↗

(On Diff #110379)

yes, right

3482 ↗

(On Diff #110379)

oh, thanks.

3570 ↗

(On Diff #110379)

oh, thanks

[dtemirbulatov]

Test cases?

Well, I could add tests here, but it is a like a main flow of this algorithm and it should be tested already here.

[RKSimon]

lib/Transforms/Vectorize/SLPVectorizer.cpp

984 ↗

(On Diff #110558)

tidyup the comment

3713 ↗

(On Diff #110558)

possibly rephrase the assertion message: "scheduler and vectorizer bundle mismatch"?

[dtemirbulatov]

update after RKSimon remarks and add test.

[RKSimon]

As discussed offline, the test cases need to be much simpler

lib/Transforms/Vectorize/SLPVectorizer.cpp

3445 ↗

(On Diff #110672)

Shouldn't the message be "ScheduleData not in scheduling region" ?

3676 ↗

(On Diff #110672)

assert message: "ScheduleData not in scheduling region" ?

[dtemirbulatov]

Update after RKSimon's remarks and replace testcase for more appropriate.

[RKSimon]

Thanks for the new tests - a few minor remarks.

test/Transforms/SLPVectorizer/X86/schedul_bundel.ll

1 ↗

(On Diff #110844)

typo - please rename the test file schedule-bundle.ll

28 ↗

(On Diff #110844)

This test doesn't seem to be working?

91 ↗

(On Diff #110844)

What is this constant store for?

99 ↗

(On Diff #110844)

You can drop these attributes if you remove the (unnecessary) tbaa tags

[dtemirbulatov]

test/Transforms/SLPVectorizer/X86/schedul_bundel.ll

28 ↗

(On Diff #110844)

yes, it is working, but the second function gives up better coverage, I am going to remove this one.

99 ↗

(On Diff #110844)

ok, thanks.

[dtemirbulatov]

update test.

[dtemirbulatov]

correct test filename spelling.

[RKSimon]

LGTM

llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp

struct BlockScheduling {
 
     ScheduleData *getScheduleData(Value *V) {
       ScheduleData *SD = ScheduleDataMap[V];
       if (SD && SD->SchedulingRegionID == SchedulingRegionID)
         return SD;
       return nullptr;
     }
 
+    ScheduleData *getScheduleData(Value *V, Value *Key) {
+      if (V == Key)
+        return getScheduleData(V);
+      auto I = ExtraScheduleDataMap.find(V);
+      if (I != ExtraScheduleDataMap.end()) {
+        ScheduleData *SD = I->second[Key];
+        if (SD && SD->SchedulingRegionID == SchedulingRegionID)
+          return SD;
+      }
+      return nullptr;
+    }
+
     bool isInSchedulingRegion(ScheduleData *SD) {
       return SD->SchedulingRegionID == SchedulingRegionID;
     }
 
     /// Marks an instruction as scheduled and puts all dependent ready
     /// instructions into the ready-list.
     template <typename ReadyListType>
     void schedule(ScheduleData *SD, ReadyListType &ReadyList) {
       SD->IsScheduled = true;
       DEBUG(dbgs() << "SLP:   schedule " << *SD << "\n");
 
       ScheduleData *BundleMember = SD;
       while (BundleMember) {
+        if (BundleMember->Inst != BundleMember->OpValue) {
+          BundleMember = BundleMember->NextInBundle;
+          continue;
+        }
         // Handle the def-use chain dependencies.
         for (Use &U : BundleMember->Inst->operands()) {
-          ScheduleData *OpDef = getScheduleData(U.get());
+          auto *I = dyn_cast<Instruction>(U.get());
+          if (!I)
+            continue;
+          doForAllOpcodes(I, [&ReadyList](ScheduleData *OpDef) {
             if (OpDef && OpDef->hasValidDependencies() &&
                 OpDef->incrementUnscheduledDeps(-1) == 0) {
-            // There are no more unscheduled dependencies after decrementing,
-            // so we can put the dependent instruction into the ready list.
+              // There are no more unscheduled dependencies after
+              // decrementing, so we can put the dependent instruction
+              // into the ready list.
               ScheduleData *DepBundle = OpDef->FirstInBundle;
               assert(!DepBundle->IsScheduled &&
                      "already scheduled bundle gets ready");
               ReadyList.insert(DepBundle);
-            DEBUG(dbgs() << "SLP:    gets ready (def): " << *DepBundle << "\n");
+              DEBUG(dbgs()
+                    << "SLP:    gets ready (def): " << *DepBundle << "\n");
             }
+          });
         }
         // Handle the memory dependencies.
         for (ScheduleData *MemoryDepSD : BundleMember->MemoryDependencies) {
           if (MemoryDepSD->incrementUnscheduledDeps(-1) == 0) {
             // There are no more unscheduled dependencies after decrementing,
             // so we can put the dependent instruction into the ready list.
             ScheduleData *DepBundle = MemoryDepSD->FirstInBundle;
             assert(!DepBundle->IsScheduled &&
                    "already scheduled bundle gets ready");
             ReadyList.insert(DepBundle);
-            DEBUG(dbgs() << "SLP:    gets ready (mem): " << *DepBundle << "\n");
+            DEBUG(dbgs() << "SLP:    gets ready (mem): " << *DepBundle
+                         << "\n");
           }
         }
         BundleMember = BundleMember->NextInBundle;
       }
     }
 
+    void doForAllOpcodes(Value *V,
+                         function_ref<void(ScheduleData *SD)> Action) {
+      if (ScheduleData *SD = getScheduleData(V))
+        Action(SD);
+      auto I = ExtraScheduleDataMap.find(V);
+      if (I != ExtraScheduleDataMap.end())
+        for (auto &P : I->second)
+          if (P.second->SchedulingRegionID == SchedulingRegionID)
+            Action(P.second);
+    }
+
     /// Put all instructions into the ReadyList which are ready for scheduling.
     template <typename ReadyListType>
     void initialFillReadyList(ReadyListType &ReadyList) {
       for (auto *I = ScheduleStart; I != ScheduleEnd; I = I->getNextNode()) {
-        ScheduleData *SD = getScheduleData(I);
+        doForAllOpcodes(I, [&ReadyList, I](ScheduleData *SD) {
           if (SD->isSchedulingEntity() && SD->isReady()) {
             ReadyList.insert(SD);
             DEBUG(dbgs() << "SLP:    initially in ready list: " << *I << "\n");
           }
+        });
       }
     }
 
     /// Checks if a bundle of instructions can be scheduled, i.e. has no
     /// cyclic dependencies. This is only a dry-run, no instructions are
     /// actually moved at this stage.
     bool tryScheduleBundle(ArrayRef<Value *> VL, BoUpSLP *SLP, Value *OpValue);
 
     /// Un-bundles a group of instructions.
     void cancelScheduling(ArrayRef<Value *> VL, Value *OpValue);
 
+    /// Allocates schedule data chunk.
+    ScheduleData *allocateScheduleDataChunks();
+
     /// Extends the scheduling region so that V is inside the region.
     /// \returns true if the region size is within the limit.
-    bool extendSchedulingRegion(Value *V);
+    bool extendSchedulingRegion(Value *V, Value *OpValue);
 
     /// Initialize the ScheduleData structures for new instructions in the
     /// scheduling region.
     void initScheduleData(Instruction *FromI, Instruction *ToI,
                           ScheduleData *PrevLoadStore,
                           ScheduleData *NextLoadStore);
 
     /// Updates the dependency information of a bundle and of all instructions/
struct BlockScheduling {
     /// of ScheduleDataChunks.
     int ChunkPos;
 
     /// Attaches ScheduleData to Instruction.
     /// Note that the mapping survives during all vectorization iterations, i.e.
     /// ScheduleData structures are recycled.
     DenseMap<Value *, ScheduleData *> ScheduleDataMap;
 
+    /// Attaches ScheduleData to Instruction with the leading key.
+    DenseMap<Value *, SmallDenseMap<Value *, ScheduleData *>>
+        ExtraScheduleDataMap;
+
     struct ReadyList : SmallVector<ScheduleData *, 8> {
       void insert(ScheduleData *SD) { push_back(SD); }
     };
 
     /// The ready-list for scheduling (only used for the dry-run).
     ReadyList ReadyInsts;
 
     /// The first instruction of the scheduling region.
bool BoUpSLP::BlockScheduling::tryScheduleBundle(ArrayRef<Value *> VL,
   ScheduleData *PrevInBundle = nullptr;
   ScheduleData *Bundle = nullptr;
   bool ReSchedule = false;
   DEBUG(dbgs() << "SLP:  bundle: " << *OpValue << "\n");
 
   // Make sure that the scheduling region contains all
   // instructions of the bundle.
   for (Value *V : VL) {
-    if (!extendSchedulingRegion(V))
+    if (!extendSchedulingRegion(V, OpValue))
       return false;
   }
 
   for (Value *V : VL) {
     ScheduleData *BundleMember = getScheduleData(V);
     assert(BundleMember &&
            "no ScheduleData for bundle member (maybe not in same basic block)");
     if (BundleMember->IsScheduled) {
bool BoUpSLP::BlockScheduling::tryScheduleBundle(ArrayRef<Value *> VL,
   }
   if (ScheduleEnd != OldScheduleEnd) {
     // The scheduling region got new instructions at the lower end (or it is a
     // new region for the first bundle). This makes it necessary to
     // recalculate all dependencies.
     // It is seldom that this needs to be done a second time after adding the
     // initial bundle to the region.
     for (auto *I = ScheduleStart; I != ScheduleEnd; I = I->getNextNode()) {
-      ScheduleData *SD = getScheduleData(I);
+      doForAllOpcodes(I, [](ScheduleData *SD) {
         SD->clearDependencies();
+      });
     }
     ReSchedule = true;
   }
   if (ReSchedule) {
     resetSchedule();
     initialFillReadyList(ReadyInsts);
   }
 
while (BundleMember) {
     BundleMember->UnscheduledDepsInBundle = BundleMember->UnscheduledDeps;
     if (BundleMember->UnscheduledDepsInBundle == 0) {
       ReadyInsts.insert(BundleMember);
     }
     BundleMember = Next;
   }
 }
 
-bool BoUpSLP::BlockScheduling::extendSchedulingRegion(Value *V) {
-  if (getScheduleData(V))
+BoUpSLP::ScheduleData *BoUpSLP::BlockScheduling::allocateScheduleDataChunks() {
+  // Allocate a new ScheduleData for the instruction.
+  if (ChunkPos >= ChunkSize) {
+    ScheduleDataChunks.push_back(llvm::make_unique<ScheduleData[]>(ChunkSize));
+    ChunkPos = 0;
+  }
+  return &(ScheduleDataChunks.back()[ChunkPos++]);
+}
+
+bool BoUpSLP::BlockScheduling::extendSchedulingRegion(Value *V,
+                                                      Value *OpValue) {
+  if (getScheduleData(V, isOneOf(OpValue, V)))
     return true;
   Instruction *I = dyn_cast<Instruction>(V);
   assert(I && "bundle member must be an instruction");
   assert(!isa<PHINode>(I) && "phi nodes don't need to be scheduled");
+  auto &&CheckSheduleForI = [this, OpValue](Instruction *I) -> bool {
+    ScheduleData *ISD = getScheduleData(I);
+    if (!ISD)
+      return false;
+    assert(isInSchedulingRegion(ISD) &&
+           "ScheduleData not in scheduling region");
+    ScheduleData *SD = allocateScheduleDataChunks();
+    SD->Inst = I;
+    SD->init(SchedulingRegionID, OpValue);
+    ExtraScheduleDataMap[I][OpValue] = SD;
+    return true;
+  };
+  if (CheckSheduleForI(I))
+    return true;
   if (!ScheduleStart) {
     // It's the first instruction in the new region.
     initScheduleData(I, I->getNextNode(), nullptr, nullptr);
     ScheduleStart = I;
     ScheduleEnd = I->getNextNode();
+    if (isOneOf(OpValue, I) != I)
+      CheckSheduleForI(I);
     assert(ScheduleEnd && "tried to vectorize a TerminatorInst?");
     DEBUG(dbgs() << "SLP:  initialize schedule region to " << *I << "\n");
     return true;
   }
   // Search up and down at the same time, because we don't know if the new
   // instruction is above or below the existing scheduling region.
   BasicBlock::reverse_iterator UpIter =
       ++ScheduleStart->getIterator().getReverse();
   BasicBlock::reverse_iterator UpperEnd = BB->rend();
   BasicBlock::iterator DownIter = ScheduleEnd->getIterator();
   BasicBlock::iterator LowerEnd = BB->end();
   for (;;) {
     if (++ScheduleRegionSize > ScheduleRegionSizeLimit) {
       DEBUG(dbgs() << "SLP:  exceeded schedule region size limit\n");
       return false;
     }
 
     if (UpIter != UpperEnd) {
       if (&*UpIter == I) {
         initScheduleData(I, ScheduleStart, nullptr, FirstLoadStoreInRegion);
         ScheduleStart = I;
+        if (isOneOf(OpValue, I) != I)
+          CheckSheduleForI(I);
         DEBUG(dbgs() << "SLP:  extend schedule region start to " << *I << "\n");
         return true;
       }
       UpIter++;
     }
     if (DownIter != LowerEnd) {
       if (&*DownIter == I) {
         initScheduleData(ScheduleEnd, I->getNextNode(), LastLoadStoreInRegion,
                          nullptr);
         ScheduleEnd = I->getNextNode();
+        if (isOneOf(OpValue, I) != I)
+          CheckSheduleForI(I);
         assert(ScheduleEnd && "tried to vectorize a TerminatorInst?");
         DEBUG(dbgs() << "SLP:  extend schedule region end to " << *I << "\n");
         return true;
       }
       DownIter++;
     }
     assert((UpIter != UpperEnd || DownIter != LowerEnd) &&
            "instruction not found in block");
for (Instruction *I = FromI; I != ToI; I = I->getNextNode()) {
     ScheduleData *SD = ScheduleDataMap[I];
     if (!SD) {
       // Allocate a new ScheduleData for the instruction.
       if (ChunkPos >= ChunkSize) {
         ScheduleDataChunks.push_back(
             llvm::make_unique<ScheduleData[]>(ChunkSize));
         ChunkPos = 0;
       }
-      SD = &(ScheduleDataChunks.back()[ChunkPos++]);
+      SD = allocateScheduleDataChunks();
       ScheduleDataMap[I] = SD;
       SD->Inst = I;
     }
     assert(!isInSchedulingRegion(SD) &&
            "new ScheduleData already in scheduling region");
     SD->init(SchedulingRegionID, I);
 
     if (I->mayReadOrWriteMemory()) {
while (BundleMember) {
       assert(isInSchedulingRegion(BundleMember));
       if (!BundleMember->hasValidDependencies()) {
 
         DEBUG(dbgs() << "SLP:       update deps of " << *BundleMember << "\n");
         BundleMember->Dependencies = 0;
         BundleMember->resetUnscheduledDeps();
 
         // Handle def-use chain dependencies.
+        if (BundleMember->OpValue != BundleMember->Inst) {
+          ScheduleData *UseSD = getScheduleData(BundleMember->Inst);
+          if (UseSD && isInSchedulingRegion(UseSD->FirstInBundle)) {
+            BundleMember->Dependencies++;
+            ScheduleData *DestBundle = UseSD->FirstInBundle;
+            if (!DestBundle->IsScheduled)
+              BundleMember->incrementUnscheduledDeps(1);
+            if (!DestBundle->hasValidDependencies())
+              WorkList.push_back(DestBundle);
+          }
+        } else {
           for (User *U : BundleMember->Inst->users()) {
             if (isa<Instruction>(U)) {
               ScheduleData *UseSD = getScheduleData(U);
               if (UseSD && isInSchedulingRegion(UseSD->FirstInBundle)) {
                 BundleMember->Dependencies++;
                 ScheduleData *DestBundle = UseSD->FirstInBundle;
                 if (!DestBundle->IsScheduled)
                   BundleMember->incrementUnscheduledDeps(1);
                 if (!DestBundle->hasValidDependencies())
                   WorkList.push_back(DestBundle);
               }
             } else {
               // I'm not sure if this can ever happen. But we need to be safe.
               // This lets the instruction/bundle never be scheduled and
               // eventually disable vectorization.
               BundleMember->Dependencies++;
               BundleMember->incrementUnscheduledDeps(1);
             }
           }
+        }
 
         // Handle the memory dependencies.
         ScheduleData *DepDest = BundleMember->NextLoadStore;
         if (DepDest) {
           Instruction *SrcInst = BundleMember->Inst;
           MemoryLocation SrcLoc = getLocation(SrcInst, SLP->AA);
           bool SrcMayWrite = BundleMember->Inst->mayWriteToMemory();
           unsigned numAliased = 0;
while (!WorkList.empty()) {
     }
   }
 }
 
 void BoUpSLP::BlockScheduling::resetSchedule() {
   assert(ScheduleStart &&
          "tried to reset schedule on block which has not been scheduled");
   for (Instruction *I = ScheduleStart; I != ScheduleEnd; I = I->getNextNode()) {
-    ScheduleData *SD = getScheduleData(I);
-    assert(isInSchedulingRegion(SD));
+    doForAllOpcodes(I, [this](ScheduleData *SD) {
+      assert(isInSchedulingRegion(SD) && 
+             "ScheduleData not in scheduling region");
       SD->IsScheduled = false;
       SD->resetUnscheduledDeps();
+    });
   }
   ReadyInsts.clear();
 }
 
 void BoUpSLP::scheduleBlock(BlockScheduling *BS) {
 
   if (!BS->ScheduleStart)
     return;
void BoUpSLP::scheduleBlock(BlockScheduling *BS) {
   std::set<ScheduleData *, ScheduleDataCompare> ReadyInsts;
 
   // Ensure that all dependency data is updated and fill the ready-list with
   // initial instructions.
   int Idx = 0;
   int NumToSchedule = 0;
   for (auto *I = BS->ScheduleStart; I != BS->ScheduleEnd;
        I = I->getNextNode()) {
-    ScheduleData *SD = BS->getScheduleData(I);
-    assert(
-        SD->isPartOfBundle() == (getTreeEntry(SD->Inst) != nullptr) &&
-        "scheduler and vectorizer have different opinion on what is a bundle");
+    BS->doForAllOpcodes(I, [this, &Idx, &NumToSchedule, BS](ScheduleData *SD) {
+      assert(SD->isPartOfBundle() ==
+                 (getTreeEntry(SD->Inst) != nullptr) &&
+             "scheduler and vectorizer bundle mismatch");
       SD->FirstInBundle->SchedulingPriority = Idx++;
       if (SD->isSchedulingEntity()) {
         BS->calculateDependencies(SD, false, this);
         NumToSchedule++;
       }
+    });
   }
   BS->initialFillReadyList(ReadyInsts);
 
   Instruction *LastScheduledInst = BS->ScheduleEnd;
 
   // Do the "real" scheduling.
   while (!ReadyInsts.empty()) {
     ScheduleData *picked = *ReadyInsts.begin();

llvm/trunk/test/Transforms/SLPVectorizer/X86/schedule-bundle.ll

+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -slp-vectorizer -slp-vectorizer -mcpu=bdver1 < %s | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@a = common local_unnamed_addr global [1 x i32] zeroinitializer, align 4
+@b = common local_unnamed_addr global [1 x i32] zeroinitializer, align 4
+
+define i32 @slp_schedule_bundle() local_unnamed_addr #0 {
+; CHECK-LABEL: @slp_schedule_bundle(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load <4 x i32>, <4 x i32>* bitcast ([1 x i32]* @b to <4 x i32>*), align 4
+; CHECK-NEXT:    [[TMP1:%.*]] = lshr <4 x i32> [[TMP0]], <i32 31, i32 31, i32 31, i32 31>
+; CHECK-NEXT:    [[TMP2:%.*]] = xor <4 x i32> <i32 1, i32 1, i32 1, i32 1>, [[TMP1]]
+; CHECK-NEXT:    store <4 x i32> [[TMP2]], <4 x i32>* bitcast ([1 x i32]* @a to <4 x i32>*), align 4
+; CHECK-NEXT:    [[TMP3:%.*]] = load i32, i32* getelementptr ([1 x i32], [1 x i32]* @b, i64 4, i64 0), align 4
+; CHECK-NEXT:    [[DOTLOBIT_4:%.*]] = lshr i32 [[TMP3]], 31
+; CHECK-NEXT:    [[DOTLOBIT_NOT_4:%.*]] = xor i32 [[DOTLOBIT_4]], 1
+; CHECK-NEXT:    store i32 [[DOTLOBIT_NOT_4]], i32* getelementptr ([1 x i32], [1 x i32]* @a, i64 4, i64 0), align 4
+; CHECK-NEXT:    [[TMP4:%.*]] = load i32, i32* getelementptr ([1 x i32], [1 x i32]* @b, i64 5, i64 0), align 4
+; CHECK-NEXT:    [[DOTLOBIT_5:%.*]] = lshr i32 [[TMP4]], 31
+; CHECK-NEXT:    [[DOTLOBIT_NOT_5:%.*]] = xor i32 [[DOTLOBIT_5]], 1
+; CHECK-NEXT:    store i32 [[DOTLOBIT_NOT_5]], i32* getelementptr ([1 x i32], [1 x i32]* @a, i64 5, i64 0), align 4
+; CHECK-NEXT:    ret i32 undef
+;
+entry:
+  %0 = load i32, i32* getelementptr inbounds ([1 x i32], [1 x i32]* @b, i64 0, i64 0), align 4
+  %.lobit = lshr i32 %0, 31
+  %.lobit.not = xor i32 %.lobit, 1
+  store i32 %.lobit.not, i32* getelementptr inbounds ([1 x i32], [1 x i32]* @a, i64 0, i64 0), align 4
+  %1 = load i32, i32* getelementptr inbounds ([1 x i32], [1 x i32]* @b, i64 1, i64 0), align 4
+  %.lobit.1 = lshr i32 %1, 31
+  %.lobit.not.1 = xor i32 %.lobit.1, 1
+  store i32 %.lobit.not.1, i32* getelementptr inbounds ([1 x i32], [1 x i32]* @a, i64 1, i64 0), align 4
+  %2 = load i32, i32* getelementptr ([1 x i32], [1 x i32]* @b, i64 2, i64 0), align 4
+  %.lobit.2 = lshr i32 %2, 31
+  %.lobit.not.2 = xor i32 %.lobit.2, 1
+  store i32 %.lobit.not.2, i32* getelementptr ([1 x i32], [1 x i32]* @a, i64 2, i64 0), align 4
+  %3 = load i32, i32* getelementptr ([1 x i32], [1 x i32]* @b, i64 3, i64 0), align 4
+  %.lobit.3 = lshr i32 %3, 31
+  %.lobit.not.3 = xor i32 %.lobit.3, 1
+  store i32 %.lobit.not.3, i32* getelementptr ([1 x i32], [1 x i32]* @a, i64 3, i64 0), align 4
+  %4 = load i32, i32* getelementptr ([1 x i32], [1 x i32]* @b, i64 4, i64 0), align 4
+  %.lobit.4 = lshr i32 %4, 31
+  %.lobit.not.4 = xor i32 %.lobit.4, 1
+  store i32 %.lobit.not.4, i32* getelementptr ([1 x i32], [1 x i32]* @a, i64 4, i64 0), align 4
+  %5 = load i32, i32* getelementptr ([1 x i32], [1 x i32]* @b, i64 5, i64 0), align 4
+  %.lobit.5 = lshr i32 %5, 31
+  %.lobit.not.5 = xor i32 %.lobit.5, 1
+  store i32 %.lobit.not.5, i32* getelementptr ([1 x i32], [1 x i32]* @a, i64 5, i64 0), align 4
+  ret i32 undef
+}