Move Instruction::isSafeToSpeculativelyExecute out of VMCore and

into Analysis as a standalone function, since there's no need for
it to be in VMCore. Also, update it to use isKnownNonZero and
other goodies available in Analysis, making it more precise,
enabling more aggressive optimization.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146610 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Analysis/ValueTracking.h b/include/llvm/Analysis/ValueTracking.h
index 6f82b2cd98d15ad73c13072ba6c925ff922922c7..85c659c631b4fa6d11e1a6bc4ade8474605f29d8 100644 (file)
--- a/include/llvm/Analysis/ValueTracking.h
+++ b/include/llvm/Analysis/ValueTracking.h
@@ -156,6 +156,27 @@ namespace llvm {
   /// are lifetime markers.
   bool onlyUsedByLifetimeMarkers(const Value *V);
 
+  /// isSafeToSpeculativelyExecute - Return true if the instruction does not
+  /// have any effects besides calculating the result and does not have
+  /// undefined behavior.
+  ///
+  /// This method never returns true for an instruction that returns true for
+  /// mayHaveSideEffects; however, this method also does some other checks in
+  /// addition. It checks for undefined behavior, like dividing by zero or
+  /// loading from an invalid pointer (but not for undefined results, like a
+  /// shift with a shift amount larger than the width of the result). It checks
+  /// for malloc and alloca because speculatively executing them might cause a
+  /// memory leak. It also returns false for instructions related to control
+  /// flow, specifically terminators and PHI nodes.
+  ///
+  /// This method only looks at the instruction itself and its operands, so if
+  /// this method returns true, it is safe to move the instruction as long as
+  /// the correct dominance relationships for the operands and users hold.
+  /// However, this method can return true for instructions that read memory;
+  /// for such instructions, moving them may change the resulting value.
+  bool isSafeToSpeculativelyExecute(const Instruction *Inst,
+                                    const TargetData *TD = 0);
+
 } // end namespace llvm
 
 #endif

diff --git a/include/llvm/Instruction.h b/include/llvm/Instruction.h
index 38973b71773c7ef1cd0702a4422e5db03f09ab4d..9c5ac4430f89967b7523f05b81ea544b3d4d0737 100644 (file)
--- a/include/llvm/Instruction.h
+++ b/include/llvm/Instruction.h
@@ -244,26 +244,6 @@ public:
     return mayWriteToMemory() || mayThrow();
   }
 
-  /// isSafeToSpeculativelyExecute - Return true if the instruction does not
-  /// have any effects besides calculating the result and does not have
-  /// undefined behavior.
-  ///
-  /// This method never returns true for an instruction that returns true for
-  /// mayHaveSideEffects; however, this method also does some other checks in
-  /// addition. It checks for undefined behavior, like dividing by zero or
-  /// loading from an invalid pointer (but not for undefined results, like a
-  /// shift with a shift amount larger than the width of the result). It checks
-  /// for malloc and alloca because speculatively executing them might cause a
-  /// memory leak. It also returns false for instructions related to control
-  /// flow, specifically terminators and PHI nodes.
-  ///
-  /// This method only looks at the instruction itself and its operands, so if
-  /// this method returns true, it is safe to move the instruction as long as
-  /// the correct dominance relationships for the operands and users hold.
-  /// However, this method can return true for instructions that read memory;
-  /// for such instructions, moving them may change the resulting value.
-  bool isSafeToSpeculativelyExecute() const;
-
   /// clone() - Create a copy of 'this' instruction that is identical in all
   /// ways except the following:
   ///   * The instruction has no parent

diff --git a/lib/Analysis/LoopInfo.cpp b/lib/Analysis/LoopInfo.cpp
index eb355537f77afe229b47d1dccc31ed66f70fa3e3..858cc642f41a66bf8f6f2d62443184fea186b9c1 100644 (file)
--- a/lib/Analysis/LoopInfo.cpp
+++ b/lib/Analysis/LoopInfo.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Instructions.h"
 #include "llvm/Analysis/Dominators.h"
 #include "llvm/Analysis/LoopIterator.h"
+#include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Assembly/Writer.h"
 #include "llvm/Support/CFG.h"
 #include "llvm/Support/CommandLine.h"
@@ -95,7 +96,7 @@ bool Loop::makeLoopInvariant(Instruction *I, bool &Changed,
   // Test if the value is already loop-invariant.
   if (isLoopInvariant(I))
     return true;
-  if (!I->isSafeToSpeculativelyExecute())
+  if (!isSafeToSpeculativelyExecute(I))
     return false;
   if (I->mayReadFromMemory())
     return false;

diff --git a/lib/Analysis/PHITransAddr.cpp b/lib/Analysis/PHITransAddr.cpp
index 86d915ff0abc8256e86b3047448388f900ee992e..80ea219cd823e774605d4e9e64999d7dd163e45b 100644 (file)
--- a/lib/Analysis/PHITransAddr.cpp
+++ b/lib/Analysis/PHITransAddr.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Analysis/PHITransAddr.h"
+#include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Constants.h"
 #include "llvm/Instructions.h"
 #include "llvm/Analysis/Dominators.h"
@@ -27,7 +28,7 @@ static bool CanPHITrans(Instruction *Inst) {
     return true;
 
   if (isa<CastInst>(Inst) &&
-      Inst->isSafeToSpeculativelyExecute())
+      isSafeToSpeculativelyExecute(Inst))
     return true;
 
   if (Inst->getOpcode() == Instruction::Add &&
@@ -186,7 +187,7 @@ Value *PHITransAddr::PHITranslateSubExpr(Value *V, BasicBlock *CurBB,
   // operands need to be phi translated, and if so, reconstruct it.
 
   if (CastInst *Cast = dyn_cast<CastInst>(Inst)) {
-    if (!Cast->isSafeToSpeculativelyExecute()) return 0;
+    if (!isSafeToSpeculativelyExecute(Cast)) return 0;
     Value *PHIIn = PHITranslateSubExpr(Cast->getOperand(0), CurBB, PredBB, DT);
     if (PHIIn == 0) return 0;
     if (PHIIn == Cast->getOperand(0))
@@ -381,7 +382,7 @@ InsertPHITranslatedSubExpr(Value *InVal, BasicBlock *CurBB,
 
   // Handle cast of PHI translatable value.
   if (CastInst *Cast = dyn_cast<CastInst>(Inst)) {
-    if (!Cast->isSafeToSpeculativelyExecute()) return 0;
+    if (!isSafeToSpeculativelyExecute(Cast)) return 0;
     Value *OpVal = InsertPHITranslatedSubExpr(Cast->getOperand(0),
                                               CurBB, PredBB, DT, NewInsts);
     if (OpVal == 0) return 0;

diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index ecc83dfceb65a6b682bf97030587056e3b1782cd..ef19e065b70769f7b164e7fcfe64d699c31fd019 100644 (file)
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -1875,3 +1875,64 @@ bool llvm::onlyUsedByLifetimeMarkers(const Value *V) {
   }
   return true;
 }
+
+bool llvm::isSafeToSpeculativelyExecute(const Instruction *Inst,
+                                        const TargetData *TD) {
+  for (unsigned i = 0, e = Inst->getNumOperands(); i != e; ++i)
+    if (Constant *C = dyn_cast<Constant>(Inst->getOperand(i)))
+      if (C->canTrap())
+        return false;
+
+  switch (Inst->getOpcode()) {
+  default:
+    return true;
+  case Instruction::UDiv:
+  case Instruction::URem:
+    // x / y is undefined if y == 0, but calcuations like x / 3 are safe.
+    return isKnownNonZero(Inst->getOperand(1), TD);
+  case Instruction::SDiv:
+  case Instruction::SRem: {
+    Value *Op = Inst->getOperand(1);
+    // x / y is undefined if y == 0
+    if (!isKnownNonZero(Op, TD))
+      return false;
+    // x / y might be undefined if y == -1
+    unsigned BitWidth = getBitWidth(Op->getType(), TD);
+    if (BitWidth == 0)
+      return false;
+    APInt KnownZero(BitWidth, 0);
+    APInt KnownOne(BitWidth, 0);
+    ComputeMaskedBits(Op, APInt::getAllOnesValue(BitWidth),
+                      KnownZero, KnownOne, TD);
+    return !!KnownZero;
+  }
+  case Instruction::Load: {
+    const LoadInst *LI = cast<LoadInst>(Inst);
+    if (!LI->isUnordered())
+      return false;
+    return LI->getPointerOperand()->isDereferenceablePointer();
+  }
+  case Instruction::Call:
+    return false; // The called function could have undefined behavior or
+                  // side-effects.
+                  // FIXME: We should special-case some intrinsics (bswap,
+                  // overflow-checking arithmetic, etc.)
+  case Instruction::VAArg:
+  case Instruction::Alloca:
+  case Instruction::Invoke:
+  case Instruction::PHI:
+  case Instruction::Store:
+  case Instruction::Ret:
+  case Instruction::Br:
+  case Instruction::IndirectBr:
+  case Instruction::Switch:
+  case Instruction::Unwind:
+  case Instruction::Unreachable:
+  case Instruction::Fence:
+  case Instruction::LandingPad:
+  case Instruction::AtomicRMW:
+  case Instruction::AtomicCmpXchg:
+  case Instruction::Resume:
+    return false; // Misc instructions which have effects
+  }
+}

diff --git a/lib/CodeGen/Analysis.cpp b/lib/CodeGen/Analysis.cpp
index fc28b21194756c7a46056f68d3a4a0cf8d6240f5..0c84be5fabaf1e3fb4c83c400ff35d16bb502e47 100644 (file)
--- a/lib/CodeGen/Analysis.cpp
+++ b/lib/CodeGen/Analysis.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/Analysis.h"
+#include "llvm/Analysis/ValueTracking.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/Function.h"
 #include "llvm/Instructions.h"
@@ -234,7 +235,7 @@ bool llvm::isInTailCallPosition(ImmutableCallSite CS, Attributes CalleeRetAttr,
   // If I will have a chain, make sure no other instruction that will have a
   // chain interposes between I and the return.
   if (I->mayHaveSideEffects() || I->mayReadFromMemory() ||
-      !I->isSafeToSpeculativelyExecute())
+      !isSafeToSpeculativelyExecute(I))
     for (BasicBlock::const_iterator BBI = prior(prior(ExitBB->end())); ;
          --BBI) {
       if (&*BBI == I)
@@ -243,7 +244,7 @@ bool llvm::isInTailCallPosition(ImmutableCallSite CS, Attributes CalleeRetAttr,
       if (isa<DbgInfoIntrinsic>(BBI))
         continue;
       if (BBI->mayHaveSideEffects() || BBI->mayReadFromMemory() ||
-          !BBI->isSafeToSpeculativelyExecute())
+          !isSafeToSpeculativelyExecute(BBI))
         return false;
     }
 

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index 65d8c6bc302724ff218cb404274e1c413aa1d7ad..8795cd853fae7d9c052d45ec470dc0f3525baf2a 100644 (file)
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -43,6 +43,7 @@
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/LoopPass.h"
 #include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Transforms/Utils/SSAUpdater.h"
 #include "llvm/Target/TargetData.h"
@@ -591,7 +592,7 @@ void LICM::hoist(Instruction &I) {
 ///
 bool LICM::isSafeToExecuteUnconditionally(Instruction &Inst) {
   // If it is not a trapping instruction, it is always safe to hoist.
-  if (Inst.isSafeToSpeculativelyExecute())
+  if (isSafeToSpeculativelyExecute(&Inst))
     return true;
 
   return isGuaranteedToExecute(Inst);

diff --git a/lib/Transforms/Scalar/Sink.cpp b/lib/Transforms/Scalar/Sink.cpp
index c83f56c4d2d7778b1712d541cf7038cf5ae48ca1..ef65c0a3a9076d8c4ca4442ba940eaeb463dd3d0 100644 (file)
--- a/lib/Transforms/Scalar/Sink.cpp
+++ b/lib/Transforms/Scalar/Sink.cpp
@@ -18,6 +18,7 @@
 #include "llvm/Analysis/Dominators.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Assembly/Writer.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Support/CFG.h"
@@ -240,7 +241,7 @@ bool Sinking::SinkInstruction(Instruction *Inst,
   if (SuccToSinkTo->getUniquePredecessor() != ParentBlock) {
     // We cannot sink a load across a critical edge - there may be stores in
     // other code paths.
-    if (!Inst->isSafeToSpeculativelyExecute()) {
+    if (!isSafeToSpeculativelyExecute(Inst)) {
       DEBUG(dbgs() << " *** PUNTING: Wont sink load along critical edge.\n");
       return false;
     }

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index b8c3ab4c60779304832d0fe30ad15c737641b853..bf2cb49bdcde66c985f5614afa629ea56e60cb11 100644 (file)
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -257,7 +257,7 @@ static bool DominatesMergePoint(Value *V, BasicBlock *BB,
   // Okay, it looks like the instruction IS in the "condition".  Check to
   // see if it's a cheap instruction to unconditionally compute, and if it
   // only uses stuff defined outside of the condition.  If so, hoist it out.
-  if (!I->isSafeToSpeculativelyExecute())
+  if (!isSafeToSpeculativelyExecute(I))
     return false;
 
   unsigned Cost = 0;
@@ -1487,7 +1487,7 @@ bool llvm::FoldBranchToCommonDest(BranchInst *BI) {
   Instruction *BonusInst = 0;
   if (&*FrontIt != Cond &&
       FrontIt->hasOneUse() && *FrontIt->use_begin() == Cond &&
-      FrontIt->isSafeToSpeculativelyExecute()) {
+      isSafeToSpeculativelyExecute(FrontIt)) {
     BonusInst = &*FrontIt;
     ++FrontIt;
     

diff --git a/lib/VMCore/Instruction.cpp b/lib/VMCore/Instruction.cpp
index 73191c19658cc0e77d3f7ca53ef9fd856ec3ec33..8c8fbf9acd46ece8e613802d4ee31f74de3161ac 100644 (file)
--- a/lib/VMCore/Instruction.cpp
+++ b/lib/VMCore/Instruction.cpp
@@ -391,59 +391,6 @@ bool Instruction::isCommutative(unsigned op) {
   }
 }
 
-bool Instruction::isSafeToSpeculativelyExecute() const {
-  for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
-    if (Constant *C = dyn_cast<Constant>(getOperand(i)))
-      if (C->canTrap())
-        return false;
-
-  switch (getOpcode()) {
-  default:
-    return true;
-  case UDiv:
-  case URem: {
-    // x / y is undefined if y == 0, but calcuations like x / 3 are safe.
-    ConstantInt *Op = dyn_cast<ConstantInt>(getOperand(1));
-    return Op && !Op->isNullValue();
-  }
-  case SDiv:
-  case SRem: {
-    // x / y is undefined if y == 0, and might be undefined if y == -1,
-    // but calcuations like x / 3 are safe.
-    ConstantInt *Op = dyn_cast<ConstantInt>(getOperand(1));
-    return Op && !Op->isNullValue() && !Op->isAllOnesValue();
-  }
-  case Load: {
-    const LoadInst *LI = cast<LoadInst>(this);
-    if (!LI->isUnordered())
-      return false;
-    return LI->getPointerOperand()->isDereferenceablePointer();
-  }
-  case Call:
-    return false; // The called function could have undefined behavior or
-                  // side-effects.
-                  // FIXME: We should special-case some intrinsics (bswap,
-                  // overflow-checking arithmetic, etc.)
-  case VAArg:
-  case Alloca:
-  case Invoke:
-  case PHI:
-  case Store:
-  case Ret:
-  case Br:
-  case IndirectBr:
-  case Switch:
-  case Unwind:
-  case Unreachable:
-  case Fence:
-  case LandingPad:
-  case AtomicRMW:
-  case AtomicCmpXchg:
-  case Resume:
-    return false; // Misc instructions which have effects
-  }
-}
-
 Instruction *Instruction::clone() const {
   Instruction *New = clone_impl();
   New->SubclassOptionalData = SubclassOptionalData;

diff --git a/test/Transforms/LICM/speculate.ll b/test/Transforms/LICM/speculate.ll
new file mode 100644 (file)
index 0000000..507b193
--- /dev/null
+++ b/test/Transforms/LICM/speculate.ll
@@ -0,0 +1,167 @@
+; RUN: opt -S -licm < %s | FileCheck %s
+
+; UDiv is safe to speculate if the denominator is known non-zero.
+
+; CHECK: @safe_udiv
+; CHECK:      %div = udiv i64 %x, %or
+; CHECK-NEXT: br label %for.body
+
+define void @safe_udiv(i64 %x, i64 %m, i64 %n, i32* %p, i64* %q) nounwind {
+entry:
+  %or = or i64 %m, 1
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.inc
+  %i.02 = phi i64 [ %inc, %for.inc ], [ 0, %entry ]
+  %arrayidx = getelementptr inbounds i32* %p, i64 %i.02
+  %0 = load i32* %arrayidx, align 4
+  %tobool = icmp eq i32 %0, 0
+  br i1 %tobool, label %for.inc, label %if.then
+
+if.then:                                          ; preds = %for.body
+  %div = udiv i64 %x, %or
+  %arrayidx1 = getelementptr inbounds i64* %q, i64 %i.02
+  store i64 %div, i64* %arrayidx1, align 8
+  br label %for.inc
+
+for.inc:                                          ; preds = %if.then, %for.body
+  %inc = add i64 %i.02, 1
+  %cmp = icmp slt i64 %inc, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.inc, %entry
+  ret void
+}
+
+; UDiv is unsafe to speculate if the denominator is not known non-zero.
+
+; CHECK: @unsafe_udiv
+; CHECK-NOT:  udiv
+; CHECK: for.body:
+
+define void @unsafe_udiv(i64 %x, i64 %m, i64 %n, i32* %p, i64* %q) nounwind {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.inc
+  %i.02 = phi i64 [ %inc, %for.inc ], [ 0, %entry ]
+  %arrayidx = getelementptr inbounds i32* %p, i64 %i.02
+  %0 = load i32* %arrayidx, align 4
+  %tobool = icmp eq i32 %0, 0
+  br i1 %tobool, label %for.inc, label %if.then
+
+if.then:                                          ; preds = %for.body
+  %div = udiv i64 %x, %m
+  %arrayidx1 = getelementptr inbounds i64* %q, i64 %i.02
+  store i64 %div, i64* %arrayidx1, align 8
+  br label %for.inc
+
+for.inc:                                          ; preds = %if.then, %for.body
+  %inc = add i64 %i.02, 1
+  %cmp = icmp slt i64 %inc, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.inc, %entry
+  ret void
+}
+
+; SDiv is safe to speculate if the denominator is known non-zero and
+; known to have at least one zero bit.
+
+; CHECK: @safe_sdiv
+; CHECK:      %div = sdiv i64 %x, %or
+; CHECK-NEXT: br label %for.body
+
+define void @safe_sdiv(i64 %x, i64 %m, i64 %n, i32* %p, i64* %q) nounwind {
+entry:
+  %and = and i64 %m, -3
+  %or = or i64 %and, 1
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.inc
+  %i.02 = phi i64 [ %inc, %for.inc ], [ 0, %entry ]
+  %arrayidx = getelementptr inbounds i32* %p, i64 %i.02
+  %0 = load i32* %arrayidx, align 4
+  %tobool = icmp eq i32 %0, 0
+  br i1 %tobool, label %for.inc, label %if.then
+
+if.then:                                          ; preds = %for.body
+  %div = sdiv i64 %x, %or
+  %arrayidx1 = getelementptr inbounds i64* %q, i64 %i.02
+  store i64 %div, i64* %arrayidx1, align 8
+  br label %for.inc
+
+for.inc:                                          ; preds = %if.then, %for.body
+  %inc = add i64 %i.02, 1
+  %cmp = icmp slt i64 %inc, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.inc, %entry
+  ret void
+}
+
+; SDiv is unsafe to speculate if the denominator is not known non-zero.
+
+; CHECK: @unsafe_sdiv_a
+; CHECK-NOT:  sdiv
+; CHECK: for.body:
+
+define void @unsafe_sdiv_a(i64 %x, i64 %m, i64 %n, i32* %p, i64* %q) nounwind {
+entry:
+  %or = or i64 %m, 1
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.inc
+  %i.02 = phi i64 [ %inc, %for.inc ], [ 0, %entry ]
+  %arrayidx = getelementptr inbounds i32* %p, i64 %i.02
+  %0 = load i32* %arrayidx, align 4
+  %tobool = icmp eq i32 %0, 0
+  br i1 %tobool, label %for.inc, label %if.then
+
+if.then:                                          ; preds = %for.body
+  %div = sdiv i64 %x, %or
+  %arrayidx1 = getelementptr inbounds i64* %q, i64 %i.02
+  store i64 %div, i64* %arrayidx1, align 8
+  br label %for.inc
+
+for.inc:                                          ; preds = %if.then, %for.body
+  %inc = add i64 %i.02, 1
+  %cmp = icmp slt i64 %inc, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.inc, %entry
+  ret void
+}
+
+; SDiv is unsafe to speculate if the denominator is not known to have a zero bit.
+
+; CHECK: @unsafe_sdiv_b
+; CHECK-NOT:  sdiv
+; CHECK: for.body:
+
+define void @unsafe_sdiv_b(i64 %x, i64 %m, i64 %n, i32* %p, i64* %q) nounwind {
+entry:
+  %and = and i64 %m, -3
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.inc
+  %i.02 = phi i64 [ %inc, %for.inc ], [ 0, %entry ]
+  %arrayidx = getelementptr inbounds i32* %p, i64 %i.02
+  %0 = load i32* %arrayidx, align 4
+  %tobool = icmp eq i32 %0, 0
+  br i1 %tobool, label %for.inc, label %if.then
+
+if.then:                                          ; preds = %for.body
+  %div = sdiv i64 %x, %and
+  %arrayidx1 = getelementptr inbounds i64* %q, i64 %i.02
+  store i64 %div, i64* %arrayidx1, align 8
+  br label %for.inc
+
+for.inc:                                          ; preds = %if.then, %for.body
+  %inc = add i64 %i.02, 1
+  %cmp = icmp slt i64 %inc, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.inc, %entry
+  ret void
+}