[TTI/CostModel] improve TTI::getGEPCost and use it in CostModel::getInstructionCost

Summary:
This patch updates TargetTransformInfoImplCRTPBase::getGEPCost to consider
addressing modes. It now returns TCC_Free when the GEP can be completely folded
to an addresing mode.

I started this patch as I refactored SLSR. Function isGEPFoldable looks common
and is indeed used by some WIP of mine. So I extracted that logic to getGEPCost.

Furthermore, I noticed getGEPCost wasn't directly tested anywhere. The best
testing bed seems CostModel, but its getInstructionCost method invokes
getAddressComputationCost for GEPs which provides very coarse estimation. So
this patch also makes getInstructionCost call the updated getGEPCost for GEPs.
This change inevitably breaks some tests because the cost model changes, but
nothing looks seriously wrong -- if we believe the new cost model is the right
way to go, these tests should be updated.

This patch is not perfect yet -- the comments in some tests need to be updated.
I want to know whether this is a right approach before fixing those details.

Reviewers: chandlerc, hfinkel

Subscribers: aschwaighofer, llvm-commits, aemerson

Differential Revision: http://reviews.llvm.org/D9819

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243250 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Analysis/TargetTransformInfo.h b/include/llvm/Analysis/TargetTransformInfo.h
index 01f00896410e29dbce7da7518c7cd819c5f28c2c..eb6fa9da369528a0458781fcba1f8dd57d3c8dcd 100644 (file)
--- a/include/llvm/Analysis/TargetTransformInfo.h
+++ b/include/llvm/Analysis/TargetTransformInfo.h
@@ -136,7 +136,8 @@ public:
   /// The contract for this function is the same as \c getOperationCost except
   /// that it supports an interface that provides extra information specific to
   /// the GEP operation.
-  unsigned getGEPCost(const Value *Ptr, ArrayRef<const Value *> Operands) const;
+  unsigned getGEPCost(Type *PointeeType, const Value *Ptr,
+                      ArrayRef<const Value *> Operands) const;
 
   /// \brief Estimate the cost of a function call when lowered.
   ///
@@ -543,7 +544,7 @@ public:
   virtual ~Concept() = 0;
   virtual const DataLayout &getDataLayout() const = 0;
   virtual unsigned getOperationCost(unsigned Opcode, Type *Ty, Type *OpTy) = 0;
-  virtual unsigned getGEPCost(const Value *Ptr,
+  virtual unsigned getGEPCost(Type *PointeeType, const Value *Ptr,
                               ArrayRef<const Value *> Operands) = 0;
   virtual unsigned getCallCost(FunctionType *FTy, int NumArgs) = 0;
   virtual unsigned getCallCost(const Function *F, int NumArgs) = 0;
@@ -643,9 +644,9 @@ public:
   unsigned getOperationCost(unsigned Opcode, Type *Ty, Type *OpTy) override {
     return Impl.getOperationCost(Opcode, Ty, OpTy);
   }
-  unsigned getGEPCost(const Value *Ptr,
+  unsigned getGEPCost(Type *PointeeType, const Value *Ptr,
                       ArrayRef<const Value *> Operands) override {
-    return Impl.getGEPCost(Ptr, Operands);
+    return Impl.getGEPCost(PointeeType, Ptr, Operands);
   }
   unsigned getCallCost(FunctionType *FTy, int NumArgs) override {
     return Impl.getCallCost(FTy, NumArgs);

diff --git a/include/llvm/Analysis/TargetTransformInfoImpl.h b/include/llvm/Analysis/TargetTransformInfoImpl.h
index 035cb04870a1cc2080247f13f94f279a4a0b0b05..505126acc0a4fb1ce267348ab9fdcd789416ff80 100644 (file)
--- a/include/llvm/Analysis/TargetTransformInfoImpl.h
+++ b/include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -19,6 +19,7 @@
 #include "llvm/IR/CallSite.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Function.h"
+#include "llvm/IR/GetElementPtrTypeIterator.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/Type.h"
 
@@ -92,7 +93,8 @@ public:
     }
   }
 
-  unsigned getGEPCost(const Value *Ptr, ArrayRef<const Value *> Operands) {
+  unsigned getGEPCost(Type *PointeeType, const Value *Ptr,
+                      ArrayRef<const Value *> Operands) {
     // In the basic model, we just assume that all-constant GEPs will be folded
     // into their uses via addressing modes.
     for (unsigned Idx = 0, Size = Operands.size(); Idx != Size; ++Idx)
@@ -378,6 +380,54 @@ public:
     return static_cast<T *>(this)->getCallCost(F, Arguments.size());
   }
 
+  using BaseT::getGEPCost;
+
+  unsigned getGEPCost(Type *PointeeType, const Value *Ptr,
+                      ArrayRef<const Value *> Operands) {
+    const GlobalValue *BaseGV = nullptr;
+    if (Ptr != nullptr) {
+      // TODO: will remove this when pointers have an opaque type.
+      assert(Ptr->getType()->getScalarType()->getPointerElementType() ==
+                 PointeeType &&
+             "explicit pointee type doesn't match operand's pointee type");
+      BaseGV = dyn_cast<GlobalValue>(Ptr->stripPointerCasts());
+    }
+    bool HasBaseReg = (BaseGV == nullptr);
+    int64_t BaseOffset = 0;
+    int64_t Scale = 0;
+
+    // Assumes the address space is 0 when Ptr is nullptr.
+    unsigned AS =
+        (Ptr == nullptr ? 0 : Ptr->getType()->getPointerAddressSpace());
+    auto GTI = gep_type_begin(PointerType::get(PointeeType, AS), Operands);
+    for (auto I = Operands.begin(); I != Operands.end(); ++I, ++GTI) {
+      if (isa<SequentialType>(*GTI)) {
+        int64_t ElementSize = DL.getTypeAllocSize(GTI.getIndexedType());
+        if (const ConstantInt *ConstIdx = dyn_cast<ConstantInt>(*I)) {
+          BaseOffset += ConstIdx->getSExtValue() * ElementSize;
+        } else {
+          // Needs scale register.
+          if (Scale != 0) {
+            // No addressing mode takes two scale registers.
+            return TTI::TCC_Basic;
+          }
+          Scale = ElementSize;
+        }
+      } else {
+        StructType *STy = cast<StructType>(*GTI);
+        uint64_t Field = cast<ConstantInt>(*I)->getZExtValue();
+        BaseOffset += DL.getStructLayout(STy)->getElementOffset(Field);
+      }
+    }
+
+    if (static_cast<T *>(this)->isLegalAddressingMode(
+            PointerType::get(*GTI, AS), const_cast<GlobalValue *>(BaseGV),
+            BaseOffset, HasBaseReg, Scale, AS)) {
+      return TTI::TCC_Free;
+    }
+    return TTI::TCC_Basic;
+  }
+
   using BaseT::getIntrinsicCost;
 
   unsigned getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
@@ -397,9 +447,9 @@ public:
       return TTI::TCC_Free; // Model all PHI nodes as free.
 
     if (const GEPOperator *GEP = dyn_cast<GEPOperator>(U)) {
-      SmallVector<const Value *, 4> Indices(GEP->idx_begin(), GEP->idx_end());
-      return static_cast<T *>(this)
-          ->getGEPCost(GEP->getPointerOperand(), Indices);
+      SmallVector<Value *, 4> Indices(GEP->idx_begin(), GEP->idx_end());
+      return static_cast<T *>(this)->getGEPCost(
+          GEP->getSourceElementType(), GEP->getPointerOperand(), Indices);
     }
 
     if (auto CS = ImmutableCallSite(U)) {

diff --git a/include/llvm/IR/GetElementPtrTypeIterator.h b/include/llvm/IR/GetElementPtrTypeIterator.h
index 6bba0ae29e987e180563a016fe88e7b4d8138bf4..7cb13fa33aa6be66d8d689c7eef000983d0373c5 100644 (file)
--- a/include/llvm/IR/GetElementPtrTypeIterator.h
+++ b/include/llvm/IR/GetElementPtrTypeIterator.h
@@ -78,7 +78,7 @@ namespace llvm {
     // current type directly.
     Type *operator->() const { return operator*(); }
 
-    Value *getOperand() const { return *OpIt; }
+    Value *getOperand() const { return const_cast<Value *>(&**OpIt); }
 
     generic_gep_type_iterator& operator++() {   // Preincrement
       if (CurTy.getInt()) {

diff --git a/lib/Analysis/CostModel.cpp b/lib/Analysis/CostModel.cpp
index b529c1a70aa3374ae0d40ff86f90c83872e2dc62..da790d745245cd079d44c6218686e705a8ee04b4 100644 (file)
--- a/lib/Analysis/CostModel.cpp
+++ b/lib/Analysis/CostModel.cpp
@@ -383,10 +383,8 @@ unsigned CostModelAnalysis::getInstructionCost(const Instruction *I) const {
     return -1;
 
   switch (I->getOpcode()) {
-  case Instruction::GetElementPtr:{
-    Type *ValTy = I->getOperand(0)->getType()->getPointerElementType();
-    return TTI->getAddressComputationCost(ValTy);
-  }
+  case Instruction::GetElementPtr:
+    return TTI->getUserCost(I);
 
   case Instruction::Ret:
   case Instruction::PHI:

diff --git a/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp b/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
index 6d9d417ef9437bb6daf4c171a09c050b49aba8cb..b2b886c4f11dbd4983a646f668c836cc549d6459 100644 (file)
--- a/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
@@ -234,6 +234,7 @@ bool StraightLineStrengthReduce::isBasisFor(const Candidate &Basis,
           Basis.CandidateKind == C.CandidateKind);
 }
 
+// TODO: use TTI->getGEPCost.
 static bool isGEPFoldable(GetElementPtrInst *GEP,
                           const TargetTransformInfo *TTI,
                           const DataLayout *DL) {

diff --git a/test/Analysis/CostModel/ARM/gep.ll b/test/Analysis/CostModel/ARM/gep.ll
index 624ca113a3022bc7b1e7f7aa464c8f1b3f733edd..a70d6d42b61b6cdf9f57c42e57ee05324787171d 100644 (file)
--- a/test/Analysis/CostModel/ARM/gep.ll
+++ b/test/Analysis/CostModel/ARM/gep.ll
@@ -3,41 +3,85 @@
 target datalayout = "e-p:32:32:32-i1:8:32-i8:8:32-i16:16:32-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:32:64-v128:32:128-a0:0:32-n32-S32"
 target triple = "thumbv7-apple-ios6.0.0"
 
-define void @test_geps() {
-  ; Cost of scalar integer geps should be one. We can't always expect it to be
-  ; folded into the instruction addressing mode.
-;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds i8, i8*
+define void @test_geps(i32 %i) {
+  ; GEPs with index 0 are essentially NOOPs.
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds i8, i8*
   %a0 = getelementptr inbounds i8, i8* undef, i32 0
-;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds i16, i16*
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds i16, i16*
   %a1 = getelementptr inbounds i16, i16* undef, i32 0
-;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds i32, i32*
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds i32, i32*
   %a2 = getelementptr inbounds i32, i32* undef, i32 0
-
-;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds i64, i64*
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds i64, i64*
   %a3 = getelementptr inbounds i64, i64* undef, i32 0
-
-  ; Cost of scalar floating point geps should be one. We cannot fold the address
-  ; computation.
-;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds float, float*
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds float, float*
   %a4 = getelementptr inbounds float, float* undef, i32 0
-;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds double, double*
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds double, double*
   %a5 = getelementptr inbounds double, double* undef, i32 0
-
-
-  ; Cost of vector geps should be one. We cannot fold the address computation.
-;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds <4 x i8>, <4 x i8>*
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x i8>, <4 x i8>*
   %a7 = getelementptr inbounds <4 x i8>, <4 x i8>* undef, i32 0
-;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds <4 x i16>, <4 x i16>*
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x i16>, <4 x i16>*
   %a8 = getelementptr inbounds <4 x i16>, <4 x i16>* undef, i32 0
-;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds <4 x i32>, <4 x i32>*
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x i32>, <4 x i32>*
   %a9 = getelementptr inbounds <4 x i32>, <4 x i32>* undef, i32 0
-;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds <4 x i64>, <4 x i64>*
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x i64>, <4 x i64>*
   %a10 = getelementptr inbounds <4 x i64>, <4 x i64>* undef, i32 0
-;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds <4 x float>, <4 x float>*
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x float>, <4 x float>*
   %a11 = getelementptr inbounds <4 x float>, <4 x float>* undef, i32 0
-;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds <4 x double>, <4 x double>*
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x double>, <4 x double>*
   %a12 = getelementptr inbounds <4 x double>, <4 x double>* undef, i32 0
 
+  ; Cost of GEPs is one if we cannot fold the address computation.
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds i8, i8*
+  %b0 = getelementptr inbounds i8, i8* undef, i32 1024
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds i16, i16*
+  %b1 = getelementptr inbounds i16, i16* undef, i32 1024
+  ; Thumb-2 cannot fold offset >= 2^12 into address computation.
+;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds i32, i32*
+  %b2 = getelementptr inbounds i32, i32* undef, i32 1024
+;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds i64, i64*
+  %b3 = getelementptr inbounds i64, i64* undef, i32 1024
+;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds float, float*
+  %b4 = getelementptr inbounds float, float* undef, i32 1024
+;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds double, double*
+  %b5 = getelementptr inbounds double, double* undef, i32 1024
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x i8>, <4 x i8>*
+  %b7 = getelementptr inbounds <4 x i8>, <4 x i8>* undef, i32 1
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x i16>, <4 x i16>*
+  %b8 = getelementptr inbounds <4 x i16>, <4 x i16>* undef, i32 1
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x i32>, <4 x i32>*
+  %b9 = getelementptr inbounds <4 x i32>, <4 x i32>* undef, i32 1
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x i64>, <4 x i64>*
+  %b10 = getelementptr inbounds <4 x i64>, <4 x i64>* undef, i32 1
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x float>, <4 x float>*
+  %b11 = getelementptr inbounds <4 x float>, <4 x float>* undef, i32 1
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x double>, <4 x double>*
+  %b12 = getelementptr inbounds <4 x double>, <4 x double>* undef, i32 1
+
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds i8, i8*
+  %c0 = getelementptr inbounds i8, i8* undef, i32 %i
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds i16, i16*
+  %c1 = getelementptr inbounds i16, i16* undef, i32 %i
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds i32, i32*
+  %c2 = getelementptr inbounds i32, i32* undef, i32 %i
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds i64, i64*
+  %c3 = getelementptr inbounds i64, i64* undef, i32 %i
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds float, float*
+  %c4 = getelementptr inbounds float, float* undef, i32 %i
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds double, double*
+  %c5 = getelementptr inbounds double, double* undef, i32 %i
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x i8>, <4 x i8>*
+  %c7 = getelementptr inbounds <4 x i8>, <4 x i8>* undef, i32 %i
+;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds <4 x i16>, <4 x i16>*
+  %c8 = getelementptr inbounds <4 x i16>, <4 x i16>* undef, i32 %i
+  ; Thumb-2 cannot fold scales larger than 8 to address computation.
+;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds <4 x i32>, <4 x i32>*
+  %c9 = getelementptr inbounds <4 x i32>, <4 x i32>* undef, i32 %i
+;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds <4 x i64>, <4 x i64>*
+  %c10 = getelementptr inbounds <4 x i64>, <4 x i64>* undef, i32 %i
+;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds <4 x float>, <4 x float>*
+  %c11 = getelementptr inbounds <4 x float>, <4 x float>* undef, i32 %i
+;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds <4 x double>, <4 x double>*
+  %c12 = getelementptr inbounds <4 x double>, <4 x double>* undef, i32 %i
 
   ret void
 }

diff --git a/test/Analysis/CostModel/no_info.ll b/test/Analysis/CostModel/no_info.ll
index 5f3b56ad9cf882f8c5fb10f9fb287d2229b99795..931669b6017689b89895ec7539a734223557e686 100644 (file)
--- a/test/Analysis/CostModel/no_info.ll
+++ b/test/Analysis/CostModel/no_info.ll
@@ -5,9 +5,27 @@
 
 ; -- No triple in this module --
 
-;CHECK: cost of 1 {{.*}} add
-;CHECK: cost of 1 {{.*}} ret
+; CHECK-LABEL: function 'no_info'
+; CHECK: cost of 1 {{.*}} add
+; CHECK: cost of 1 {{.*}} ret
 define i32 @no_info(i32 %arg) {
   %e = add i32 %arg, %arg
   ret i32 %e
 }
+
+define i8 @addressing_mode_reg_reg(i8* %a, i32 %b) {
+; CHECK-LABEL: function 'addressing_mode_reg_reg'
+  %p = getelementptr i8, i8* %a, i32 %b ; NoTTI accepts reg+reg addressing.
+; CHECK: cost of 0 {{.*}} getelementptr
+  %v = load i8, i8* %p
+  ret i8 %v
+}
+
+; CHECK-LABEL: function 'addressing_mode_scaled_reg'
+define i32 @addressing_mode_scaled_reg(i32* %a, i32 %b) {
+  ; NoTTI rejects reg+scale*reg addressing.
+  %p = getelementptr i32, i32* %a, i32 %b
+; CHECK: cost of 1 {{.*}} getelementptr
+  %v = load i32, i32* %p
+  ret i32 %v
+}

diff --git a/test/Transforms/LoopUnroll/X86/partial.ll b/test/Transforms/LoopUnroll/X86/partial.ll
index 4566f792deb427704ac2d5f46cfef2a4e2b6116e..104a38779e52b73473c7451a3bcfb2fd086c1d1e 100644 (file)
--- a/test/Transforms/LoopUnroll/X86/partial.ll
+++ b/test/Transforms/LoopUnroll/X86/partial.ll
@@ -86,17 +86,20 @@ for.body:                                         ; preds = %entry, %for.body
   %reduction.026 = phi i16 [ %add14, %for.body ], [ 0, %entry ]
   %arrayidx = getelementptr inbounds i16, i16* %arr, i64 %indvars.iv
   %0 = load i16, i16* %arrayidx, align 2
-  %add = add i16 %0, %reduction.026
+  %mul = shl i16 %0, 1
+  %add = add i16 %mul, %reduction.026
   %sext = mul i64 %indvars.iv, 12884901888
   %idxprom3 = ashr exact i64 %sext, 32
   %arrayidx4 = getelementptr inbounds i16, i16* %arr, i64 %idxprom3
   %1 = load i16, i16* %arrayidx4, align 2
-  %add7 = add i16 %add, %1
+  %mul2 = shl i16 %1, 1
+  %add7 = add i16 %add, %mul2
   %sext28 = mul i64 %indvars.iv, 21474836480
   %idxprom10 = ashr exact i64 %sext28, 32
   %arrayidx11 = getelementptr inbounds i16, i16* %arr, i64 %idxprom10
   %2 = load i16, i16* %arrayidx11, align 2
-  %add14 = add i16 %add7, %2
+  %mul3 = shl i16 %2, 1
+  %add14 = add i16 %add7, %mul3
   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
   %lftr.wideiv = trunc i64 %indvars.iv.next to i32
   %exitcond = icmp eq i32 %lftr.wideiv, %n

diff --git a/test/Transforms/LoopVectorize/X86/metadata-enable.ll b/test/Transforms/LoopVectorize/X86/metadata-enable.ll
index ba8e11e587490cedb6edf3bb52edc325aaf35736..74c0c16086fedb84a5d54c3d378460615605b1a4 100644 (file)
--- a/test/Transforms/LoopVectorize/X86/metadata-enable.ll
+++ b/test/Transforms/LoopVectorize/X86/metadata-enable.ll
@@ -60,7 +60,7 @@ for.body:                                         ; preds = %for.body, %entry
   %arrayidx2 = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
   store i32 %add, i32* %arrayidx2, align 4
   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
-  %exitcond = icmp eq i64 %indvars.iv.next, 32
+  %exitcond = icmp eq i64 %indvars.iv.next, 64
   br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !0
 
 for.end:                                          ; preds = %for.body
@@ -111,7 +111,7 @@ for.body:                                         ; preds = %for.body, %entry
   %arrayidx2 = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
   store i32 %add, i32* %arrayidx2, align 4
   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
-  %exitcond = icmp eq i64 %indvars.iv.next, 32
+  %exitcond = icmp eq i64 %indvars.iv.next, 64
   br i1 %exitcond, label %for.end, label %for.body
 
 for.end:                                          ; preds = %for.body
@@ -162,7 +162,7 @@ for.body:                                         ; preds = %for.body, %entry
   %arrayidx2 = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
   store i32 %add, i32* %arrayidx2, align 4
   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
-  %exitcond = icmp eq i64 %indvars.iv.next, 32
+  %exitcond = icmp eq i64 %indvars.iv.next, 64
   br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !2
 
 for.end:                                          ; preds = %for.body