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-rw-r--r--include/llvm-c/Transforms/Scalar.h3
-rw-r--r--include/llvm/InitializePasses.h1
-rw-r--r--include/llvm/LinkAllPasses.h1
-rw-r--r--include/llvm/Transforms/Scalar.h6
-rw-r--r--lib/Transforms/IPO/PassManagerBuilder.cpp6
-rw-r--r--lib/Transforms/Scalar/CMakeLists.txt1
-rw-r--r--lib/Transforms/Scalar/LoopRerollPass.cpp1184
-rw-r--r--lib/Transforms/Scalar/Scalar.cpp5
-rw-r--r--test/Transforms/LoopReroll/basic.ll327
-rw-r--r--test/Transforms/LoopReroll/reduction.ll96
10 files changed, 1630 insertions, 0 deletions
diff --git a/include/llvm-c/Transforms/Scalar.h b/include/llvm-c/Transforms/Scalar.h
index 2456c6c726..355e8dc299 100644
--- a/include/llvm-c/Transforms/Scalar.h
+++ b/include/llvm-c/Transforms/Scalar.h
@@ -65,6 +65,9 @@ void LLVMAddLoopIdiomPass(LLVMPassManagerRef PM);
/** See llvm::createLoopRotatePass function. */
void LLVMAddLoopRotatePass(LLVMPassManagerRef PM);
+/** See llvm::createLoopRerollPass function. */
+void LLVMAddLoopRerollPass(LLVMPassManagerRef PM);
+
/** See llvm::createLoopUnrollPass function. */
void LLVMAddLoopUnrollPass(LLVMPassManagerRef PM);
diff --git a/include/llvm/InitializePasses.h b/include/llvm/InitializePasses.h
index acfe3bd366..aefb3c065b 100644
--- a/include/llvm/InitializePasses.h
+++ b/include/llvm/InitializePasses.h
@@ -162,6 +162,7 @@ void initializeLoopRotatePass(PassRegistry&);
void initializeLoopSimplifyPass(PassRegistry&);
void initializeLoopStrengthReducePass(PassRegistry&);
void initializeGlobalMergePass(PassRegistry&);
+void initializeLoopRerollPass(PassRegistry&);
void initializeLoopUnrollPass(PassRegistry&);
void initializeLoopUnswitchPass(PassRegistry&);
void initializeLoopIdiomRecognizePass(PassRegistry&);
diff --git a/include/llvm/LinkAllPasses.h b/include/llvm/LinkAllPasses.h
index d97e54c205..8183fa2992 100644
--- a/include/llvm/LinkAllPasses.h
+++ b/include/llvm/LinkAllPasses.h
@@ -91,6 +91,7 @@ namespace {
(void) llvm::createLoopExtractorPass();
(void) llvm::createLoopSimplifyPass();
(void) llvm::createLoopStrengthReducePass();
+ (void) llvm::createLoopRerollPass();
(void) llvm::createLoopUnrollPass();
(void) llvm::createLoopUnswitchPass();
(void) llvm::createLoopIdiomPass();
diff --git a/include/llvm/Transforms/Scalar.h b/include/llvm/Transforms/Scalar.h
index 5d06157577..1521c4cff5 100644
--- a/include/llvm/Transforms/Scalar.h
+++ b/include/llvm/Transforms/Scalar.h
@@ -145,6 +145,12 @@ Pass *createLoopUnrollPass(int Threshold = -1, int Count = -1,
//===----------------------------------------------------------------------===//
//
+// LoopReroll - This pass is a simple loop rerolling pass.
+//
+Pass *createLoopRerollPass();
+
+//===----------------------------------------------------------------------===//
+//
// LoopRotate - This pass is a simple loop rotating pass.
//
Pass *createLoopRotatePass();
diff --git a/lib/Transforms/IPO/PassManagerBuilder.cpp b/lib/Transforms/IPO/PassManagerBuilder.cpp
index 1386201094..5399e6865a 100644
--- a/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -54,6 +54,10 @@ static cl::opt<bool> UseNewSROA("use-new-sroa",
cl::init(true), cl::Hidden,
cl::desc("Enable the new, experimental SROA pass"));
+static cl::opt<bool>
+RunLoopRerolling("reroll-loops", cl::Hidden,
+ cl::desc("Run the loop rerolling pass"));
+
PassManagerBuilder::PassManagerBuilder() {
OptLevel = 2;
SizeLevel = 0;
@@ -216,6 +220,8 @@ void PassManagerBuilder::populateModulePassManager(PassManagerBase &MPM) {
addExtensionsToPM(EP_ScalarOptimizerLate, MPM);
+ if (RunLoopRerolling)
+ MPM.add(createLoopRerollPass());
if (SLPVectorize)
MPM.add(createSLPVectorizerPass()); // Vectorize parallel scalar chains.
diff --git a/lib/Transforms/Scalar/CMakeLists.txt b/lib/Transforms/Scalar/CMakeLists.txt
index ee456004a6..626c810a50 100644
--- a/lib/Transforms/Scalar/CMakeLists.txt
+++ b/lib/Transforms/Scalar/CMakeLists.txt
@@ -16,6 +16,7 @@ add_llvm_library(LLVMScalarOpts
LoopInstSimplify.cpp
LoopRotation.cpp
LoopStrengthReduce.cpp
+ LoopRerollPass.cpp
LoopUnrollPass.cpp
LoopUnswitch.cpp
LowerAtomic.cpp
diff --git a/lib/Transforms/Scalar/LoopRerollPass.cpp b/lib/Transforms/Scalar/LoopRerollPass.cpp
new file mode 100644
index 0000000000..eb39cd0971
--- /dev/null
+++ b/lib/Transforms/Scalar/LoopRerollPass.cpp
@@ -0,0 +1,1184 @@
+//===-- LoopReroll.cpp - Loop rerolling pass ------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass implements a simple loop reroller.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "loop-reroll"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/AliasSetTracker.h"
+#include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/Analysis/ScalarEvolutionExpander.h"
+#include "llvm/Analysis/ScalarEvolutionExpressions.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetLibraryInfo.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/LoopUtils.h"
+
+using namespace llvm;
+
+STATISTIC(NumRerolledLoops, "Number of rerolled loops");
+
+static cl::opt<unsigned>
+MaxInc("max-reroll-increment", cl::init(2048), cl::Hidden,
+ cl::desc("The maximum increment for loop rerolling"));
+
+// This loop re-rolling transformation aims to transform loops like this:
+//
+// int foo(int a);
+// void bar(int *x) {
+// for (int i = 0; i < 500; i += 3) {
+// foo(i);
+// foo(i+1);
+// foo(i+2);
+// }
+// }
+//
+// into a loop like this:
+//
+// void bar(int *x) {
+// for (int i = 0; i < 500; ++i)
+// foo(i);
+// }
+//
+// It does this by looking for loops that, besides the latch code, are composed
+// of isomorphic DAGs of instructions, with each DAG rooted at some increment
+// to the induction variable, and where each DAG is isomorphic to the DAG
+// rooted at the induction variable (excepting the sub-DAGs which root the
+// other induction-variable increments). In other words, we're looking for loop
+// bodies of the form:
+//
+// %iv = phi [ (preheader, ...), (body, %iv.next) ]
+// f(%iv)
+// %iv.1 = add %iv, 1 <-- a root increment
+// f(%iv.1)
+// %iv.2 = add %iv, 2 <-- a root increment
+// f(%iv.2)
+// %iv.scale_m_1 = add %iv, scale-1 <-- a root increment
+// f(%iv.scale_m_1)
+// ...
+// %iv.next = add %iv, scale
+// %cmp = icmp(%iv, ...)
+// br %cmp, header, exit
+//
+// where each f(i) is a set of instructions that, collectively, are a function
+// only of i (and other loop-invariant values).
+//
+// As a special case, we can also reroll loops like this:
+//
+// int foo(int);
+// void bar(int *x) {
+// for (int i = 0; i < 500; ++i) {
+// x[3*i] = foo(0);
+// x[3*i+1] = foo(0);
+// x[3*i+2] = foo(0);
+// }
+// }
+//
+// into this:
+//
+// void bar(int *x) {
+// for (int i = 0; i < 1500; ++i)
+// x[i] = foo(0);
+// }
+//
+// in which case, we're looking for inputs like this:
+//
+// %iv = phi [ (preheader, ...), (body, %iv.next) ]
+// %scaled.iv = mul %iv, scale
+// f(%scaled.iv)
+// %scaled.iv.1 = add %scaled.iv, 1
+// f(%scaled.iv.1)
+// %scaled.iv.2 = add %scaled.iv, 2
+// f(%scaled.iv.2)
+// %scaled.iv.scale_m_1 = add %scaled.iv, scale-1
+// f(%scaled.iv.scale_m_1)
+// ...
+// %iv.next = add %iv, 1
+// %cmp = icmp(%iv, ...)
+// br %cmp, header, exit
+
+namespace {
+ class LoopReroll : public LoopPass {
+ public:
+ static char ID; // Pass ID, replacement for typeid
+ LoopReroll() : LoopPass(ID) {
+ initializeLoopRerollPass(*PassRegistry::getPassRegistry());
+ }
+
+ bool runOnLoop(Loop *L, LPPassManager &LPM);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<AliasAnalysis>();
+ AU.addRequired<LoopInfo>();
+ AU.addPreserved<LoopInfo>();
+ AU.addRequired<DominatorTree>();
+ AU.addPreserved<DominatorTree>();
+ AU.addRequired<ScalarEvolution>();
+ AU.addRequired<TargetLibraryInfo>();
+ }
+
+protected:
+ AliasAnalysis *AA;
+ LoopInfo *LI;
+ ScalarEvolution *SE;
+ DataLayout *DL;
+ TargetLibraryInfo *TLI;
+ DominatorTree *DT;
+
+ typedef SmallVector<Instruction *, 16> SmallInstructionVector;
+ typedef SmallSet<Instruction *, 16> SmallInstructionSet;
+
+ // A chain of isomorphic instructions, indentified by a single-use PHI,
+ // representing a reduction. Only the last value may be used outside the
+ // loop.
+ struct SimpleLoopReduction {
+ SimpleLoopReduction(Instruction *P, Loop *L)
+ : Valid(false), Instructions(1, P) {
+ assert(isa<PHINode>(P) && "First reduction instruction must be a PHI");
+ add(L);
+ }
+
+ bool valid() const {
+ return Valid;
+ }
+
+ Instruction *getPHI() const {
+ assert(Valid && "Using invalid reduction");
+ return Instructions.front();
+ }
+
+ Instruction *getReducedValue() const {
+ assert(Valid && "Using invalid reduction");
+ return Instructions.back();
+ }
+
+ Instruction *get(size_t i) const {
+ assert(Valid && "Using invalid reduction");
+ return Instructions[i+1];
+ }
+
+ Instruction *operator [] (size_t i) const { return get(i); }
+
+ // The size, ignoring the initial PHI.
+ size_t size() const {
+ assert(Valid && "Using invalid reduction");
+ return Instructions.size()-1;
+ }
+
+ typedef SmallInstructionVector::iterator iterator;
+ typedef SmallInstructionVector::const_iterator const_iterator;
+
+ iterator begin() {
+ assert(Valid && "Using invalid reduction");
+ return llvm::next(Instructions.begin());
+ }
+
+ const_iterator begin() const {
+ assert(Valid && "Using invalid reduction");
+ return llvm::next(Instructions.begin());
+ }
+
+ iterator end() { return Instructions.end(); }
+ const_iterator end() const { return Instructions.end(); }
+
+ protected:
+ bool Valid;
+ SmallInstructionVector Instructions;
+
+ void add(Loop *L);
+ };
+
+ // The set of all reductions, and state tracking of possible reductions
+ // during loop instruction processing.
+ struct ReductionTracker {
+ typedef SmallVector<SimpleLoopReduction, 16> SmallReductionVector;
+
+ // Add a new possible reduction.
+ void addSLR(SimpleLoopReduction &SLR) {
+ PossibleReds.push_back(SLR);
+ }
+
+ // Setup to track possible reductions corresponding to the provided
+ // rerolling scale. Only reductions with a number of non-PHI instructions
+ // that is divisible by the scale are considered. Three instructions sets
+ // are filled in:
+ // - A set of all possible instructions in eligible reductions.
+ // - A set of all PHIs in eligible reductions
+ // - A set of all reduced values (last instructions) in eligible reductions.
+ void restrictToScale(uint64_t Scale,
+ SmallInstructionSet &PossibleRedSet,
+ SmallInstructionSet &PossibleRedPHISet,
+ SmallInstructionSet &PossibleRedLastSet) {
+ PossibleRedIdx.clear();
+ PossibleRedIter.clear();
+ Reds.clear();
+
+ for (unsigned i = 0, e = PossibleReds.size(); i != e; ++i)
+ if (PossibleReds[i].size() % Scale == 0) {
+ PossibleRedLastSet.insert(PossibleReds[i].getReducedValue());
+ PossibleRedPHISet.insert(PossibleReds[i].getPHI());
+
+ PossibleRedSet.insert(PossibleReds[i].getPHI());
+ PossibleRedIdx[PossibleReds[i].getPHI()] = i;
+ for (SimpleLoopReduction::iterator J = PossibleReds[i].begin(),
+ JE = PossibleReds[i].end(); J != JE; ++J) {
+ PossibleRedSet.insert(*J);
+ PossibleRedIdx[*J] = i;
+ }
+ }
+ }
+
+ // The functions below are used while processing the loop instructions.
+
+ // Are the two instructions both from reductions, and furthermore, from
+ // the same reduction?
+ bool isPairInSame(Instruction *J1, Instruction *J2) {
+ DenseMap<Instruction *, int>::iterator J1I = PossibleRedIdx.find(J1);
+ if (J1I != PossibleRedIdx.end()) {
+ DenseMap<Instruction *, int>::iterator J2I = PossibleRedIdx.find(J2);
+ if (J2I != PossibleRedIdx.end() && J1I->second == J2I->second)
+ return true;
+ }
+
+ return false;
+ }
+
+ // The two provided instructions, the first from the base iteration, and
+ // the second from iteration i, form a matched pair. If these are part of
+ // a reduction, record that fact.
+ void recordPair(Instruction *J1, Instruction *J2, unsigned i) {
+ if (PossibleRedIdx.count(J1)) {
+ assert(PossibleRedIdx.count(J2) &&
+ "Recording reduction vs. non-reduction instruction?");
+
+ PossibleRedIter[J1] = 0;
+ PossibleRedIter[J2] = i;
+
+ int Idx = PossibleRedIdx[J1];
+ assert(Idx == PossibleRedIdx[J2] &&
+ "Recording pair from different reductions?");
+ Reds.insert(PossibleRedIdx[J1]);
+ }
+ }
+
+ // The functions below can be called after we've finished processing all
+ // instructions in the loop, and we know which reductions were selected.
+
+ // Is the provided instruction the PHI of a reduction selected for
+ // rerolling?
+ bool isSelectedPHI(Instruction *J) {
+ if (!isa<PHINode>(J))
+ return false;
+
+ for (DenseSet<int>::iterator RI = Reds.begin(), RIE = Reds.end();
+ RI != RIE; ++RI) {
+ int i = *RI;
+ if (cast<Instruction>(J) == PossibleReds[i].getPHI())
+ return true;
+ }
+
+ return false;
+ }
+
+ bool validateSelected();
+ void replaceSelected();
+
+ protected:
+ // The vector of all possible reductions (for any scale).
+ SmallReductionVector PossibleReds;
+
+ DenseMap<Instruction *, int> PossibleRedIdx;
+ DenseMap<Instruction *, int> PossibleRedIter;
+ DenseSet<int> Reds;
+ };
+
+ void collectPossibleIVs(Loop *L, SmallInstructionVector &PossibleIVs);
+ void collectPossibleReductions(Loop *L,
+ ReductionTracker &Reductions);
+ void collectInLoopUserSet(Loop *L,
+ const SmallInstructionVector &Roots,
+ const SmallInstructionSet &Exclude,
+ const SmallInstructionSet &Final,
+ DenseSet<Instruction *> &Users);
+ void collectInLoopUserSet(Loop *L,
+ Instruction * Root,
+ const SmallInstructionSet &Exclude,
+ const SmallInstructionSet &Final,
+ DenseSet<Instruction *> &Users);
+ bool findScaleFromMul(Instruction *RealIV, uint64_t &Scale,
+ Instruction *&IV,
+ SmallInstructionVector &LoopIncs);
+ bool collectAllRoots(Loop *L, uint64_t Inc, uint64_t Scale, Instruction *IV,
+ SmallVector<SmallInstructionVector, 32> &Roots,
+ SmallInstructionSet &AllRoots,
+ SmallInstructionVector &LoopIncs);
+ bool reroll(Instruction *IV, Loop *L, BasicBlock *Header, const SCEV *IterCount,
+ ReductionTracker &Reductions);
+ };
+}
+
+char LoopReroll::ID = 0;
+INITIALIZE_PASS_BEGIN(LoopReroll, "loop-reroll", "Reroll loops", false, false)
+INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
+INITIALIZE_PASS_DEPENDENCY(LoopInfo)
+INITIALIZE_PASS_DEPENDENCY(DominatorTree)
+INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
+INITIALIZE_PASS_END(LoopReroll, "loop-reroll", "Reroll loops", false, false)
+
+Pass *llvm::createLoopRerollPass() {
+ return new LoopReroll;
+}
+
+// Returns true if the provided instruction is used outside the given loop.
+// This operates like Instruction::isUsedOutsideOfBlock, but considers PHIs in
+// non-loop blocks to be outside the loop.
+static bool hasUsesOutsideLoop(Instruction *I, Loop *L) {
+ for (Value::use_iterator UI = I->use_begin(),
+ UIE = I->use_end(); UI != UIE; ++UI) {
+ Instruction *User = cast<Instruction>(*UI);
+ if (!L->contains(User))
+ return true;
+ }
+
+ return false;
+}
+
+// Collect the list of loop induction variables with respect to which it might
+// be possible to reroll the loop.
+void LoopReroll::collectPossibleIVs(Loop *L,
+ SmallInstructionVector &PossibleIVs) {
+ BasicBlock *Header = L->getHeader();
+ for (BasicBlock::iterator I = Header->begin(),
+ IE = Header->getFirstInsertionPt(); I != IE; ++I) {
+ if (!isa<PHINode>(I))
+ continue;
+ if (!I->getType()->isIntegerTy())
+ continue;
+
+ if (const SCEVAddRecExpr *PHISCEV =
+ dyn_cast<SCEVAddRecExpr>(SE->getSCEV(I))) {
+ if (PHISCEV->getLoop() != L)
+ continue;
+ if (!PHISCEV->isAffine())
+ continue;
+ if (const SCEVConstant *IncSCEV =
+ dyn_cast<SCEVConstant>(PHISCEV->getStepRecurrence(*SE))) {
+ if (!IncSCEV->getValue()->getValue().isStrictlyPositive())
+ continue;
+ if (IncSCEV->getValue()->uge(MaxInc))
+ continue;
+
+ DEBUG(dbgs() << "LRR: Possible IV: " << *I << " = " <<
+ *PHISCEV << "\n");
+ PossibleIVs.push_back(I);
+ }
+ }
+ }
+}
+
+// Add the remainder of the reduction-variable chain to the instruction vector
+// (the initial PHINode has already been added). If successful, the object is
+// marked as valid.
+void LoopReroll::SimpleLoopReduction::add(Loop *L) {
+ assert(!Valid && "Cannot add to an already-valid chain");
+
+ // The reduction variable must be a chain of single-use instructions
+ // (including the PHI), except for the last value (which is used by the PHI
+ // and also outside the loop).
+ Instruction *C = Instructions.front();
+
+ do {
+ C = cast<Instruction>(*C->use_begin());
+ if (C->hasOneUse()) {
+ if (!C->isBinaryOp())
+ return;
+
+ if (!(isa<PHINode>(Instructions.back()) ||
+ C->isSameOperationAs(Instructions.back())))
+ return;
+
+ Instructions.push_back(C);
+ }
+ } while (C->hasOneUse());
+
+ if (Instructions.size() < 2 ||
+ !C->isSameOperationAs(Instructions.back()) ||
+ C->use_begin() == C->use_end())
+ return;
+
+ // C is now the (potential) last instruction in the reduction chain.
+ for (Value::use_iterator UI = C->use_begin(), UIE = C->use_end();
+ UI != UIE; ++UI) {
+ // The only in-loop user can be the initial PHI.
+ if (L->contains(cast<Instruction>(*UI)))
+ if (cast<Instruction>(*UI ) != Instructions.front())
+ return;
+ }
+
+ Instructions.push_back(C);
+ Valid = true;
+}
+
+// Collect the vector of possible reduction variables.
+void LoopReroll::collectPossibleReductions(Loop *L,
+ ReductionTracker &Reductions) {
+ BasicBlock *Header = L->getHeader();
+ for (BasicBlock::iterator I = Header->begin(),
+ IE = Header->getFirstInsertionPt(); I != IE; ++I) {
+ if (!isa<PHINode>(I))
+ continue;
+ if (!I->getType()->isSingleValueType())
+ continue;
+
+ SimpleLoopReduction SLR(I, L);
+ if (!SLR.valid())
+ continue;
+
+ DEBUG(dbgs() << "LRR: Possible reduction: " << *I << " (with " <<
+ SLR.size() << " chained instructions)\n");
+ Reductions.addSLR(SLR);
+ }
+}
+
+// Collect the set of all users of the provided root instruction. This set of
+// users contains not only the direct users of the root instruction, but also
+// all users of those users, and so on. There are two exceptions:
+//
+// 1. Instructions in the set of excluded instructions are never added to the
+// use set (even if they are users). This is used, for example, to exclude
+// including root increments in the use set of the primary IV.
+//
+// 2. Instructions in the set of final instructions are added to the use set
+// if they are users, but their users are not added. This is used, for
+// example, to prevent a reduction update from forcing all later reduction
+// updates into the use set.
+void LoopReroll::collectInLoopUserSet(Loop *L,
+ Instruction *Root, const SmallInstructionSet &Exclude,
+ const SmallInstructionSet &Final,
+ DenseSet<Instruction *> &Users) {
+ SmallInstructionVector Queue(1, Root);
+ while (!Queue.empty()) {
+ Instruction *I = Queue.pop_back_val();
+ if (!Users.insert(I).second)
+ continue;
+
+ if (!Final.count(I))
+ for (Value::use_iterator UI = I->use_begin(),
+ UIE = I->use_end(); UI != UIE; ++UI) {
+ Instruction *User = cast<Instruction>(*UI);
+ if (PHINode *PN = dyn_cast<PHINode>(User)) {
+ // Ignore "wrap-around" uses to PHIs of this loop's header.
+ if (PN->getIncomingBlock(UI) == L->getHeader())
+ continue;
+ }
+
+ if (L->contains(User) && !Exclude.count(User)) {
+ Queue.push_back(User);
+ }
+ }
+
+ // We also want to collect single-user "feeder" values.
+ for (User::op_iterator OI = I->op_begin(),
+ OIE = I->op_end(); OI != OIE; ++OI) {
+ if (Instruction *Op = dyn_cast<Instruction>(*OI))
+ if (Op->hasOneUse() && L->contains(Op) && !Exclude.count(Op) &&
+ !Final.count(Op))
+ Queue.push_back(Op);
+ }
+ }
+}
+
+// Collect all of the users of all of the provided root instructions (combined
+// into a single set).
+void LoopReroll::collectInLoopUserSet(Loop *L,
+ const SmallInstructionVector &Roots,
+ const SmallInstructionSet &Exclude,
+ const SmallInstructionSet &Final,
+ DenseSet<Instruction *> &Users) {
+ for (SmallInstructionVector::const_iterator I = Roots.begin(),
+ IE = Roots.end(); I != IE; ++I)
+ collectInLoopUserSet(L, *I, Exclude, Final, Users);
+}
+
+static bool isSimpleLoadStore(Instruction *I) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(I))
+ return LI->isSimple();
+ if (StoreInst *SI = dyn_cast<StoreInst>(I))
+ return SI->isSimple();
+ if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I))
+ return !MI->isVolatile();
+ return false;
+}
+
+// Recognize loops that are setup like this:
+//
+// %iv = phi [ (preheader, ...), (body, %iv.next) ]
+// %scaled.iv = mul %iv, scale
+// f(%scaled.iv)
+// %scaled.iv.1 = add %scaled.iv, 1
+// f(%scaled.iv.1)
+// %scaled.iv.2 = add %scaled.iv, 2
+// f(%scaled.iv.2)
+// %scaled.iv.scale_m_1 = add %scaled.iv, scale-1
+// f(%scaled.iv.scale_m_1)
+// ...
+// %iv.next = add %iv, 1
+// %cmp = icmp(%iv, ...)
+// br %cmp, header, exit
+//
+// and, if found, set IV = %scaled.iv, and add %iv.next to LoopIncs.
+bool LoopReroll::findScaleFromMul(Instruction *RealIV, uint64_t &Scale,
+ Instruction *&IV,
+ SmallInstructionVector &LoopIncs) {
+ // This is a special case: here we're looking for all uses (except for
+ // the increment) to be multiplied by a common factor. The increment must
+ // be by one. This is to capture loops like:
+ // for (int i = 0; i < 500; ++i) {
+ // foo(3*i); foo(3*i+1); foo(3*i+2);
+ // }
+ if (RealIV->getNumUses() != 2)
+ return false;
+ const SCEVAddRecExpr *RealIVSCEV = cast<SCEVAddRecExpr>(SE->getSCEV(RealIV));
+ Instruction *User1 = cast<Instruction>(*RealIV->use_begin()),
+ *User2 = cast<Instruction>(*llvm::next(RealIV->use_begin()));
+ if (!SE->isSCEVable(User1->getType()) || !SE->isSCEVable(User2->getType()))
+ return false;
+ const SCEVAddRecExpr *User1SCEV =
+ dyn_cast<SCEVAddRecExpr>(SE->getSCEV(User1)),
+ *User2SCEV =
+ dyn_cast<SCEVAddRecExpr>(SE->getSCEV(User2));
+ if (!User1SCEV || !User1SCEV->isAffine() ||
+ !User2SCEV || !User2SCEV->isAffine())
+ return false;
+
+ // We assume below that User1 is the scale multiply and User2 is the
+ // increment. If this can't be true, then swap them.
+ if (User1SCEV == RealIVSCEV->getPostIncExpr(*SE)) {
+ std::swap(User1, User2);
+ std::swap(User1SCEV, User2SCEV);
+ }
+
+ if (User2SCEV != RealIVSCEV->getPostIncExpr(*SE))
+ return false;
+ assert(User2SCEV->getStepRecurrence(*SE)->isOne() &&
+ "Invalid non-unit step for multiplicative scaling");
+ LoopIncs.push_back(User2);
+
+ if (const SCEVConstant *MulScale =
+ dyn_cast<SCEVConstant>(User1SCEV->getStepRecurrence(*SE))) {
+ // Make sure that both the start and step have the same multiplier.
+ if (RealIVSCEV->getStart()->getType() != MulScale->getType())
+ return false;
+ if (SE->getMulExpr(RealIVSCEV->getStart(), MulScale) !=
+ User1SCEV->getStart())
+ return false;
+
+ ConstantInt *MulScaleCI = MulScale->getValue();
+ if (!MulScaleCI->uge(2) || MulScaleCI->uge(MaxInc))
+ return false;
+ Scale = MulScaleCI->getZExtValue();
+ IV = User1;
+ } else
+ return false;
+
+ DEBUG(dbgs() << "LRR: Found possible scaling " << *User1 << "\n");
+ return true;
+}
+
+// Collect all root increments with respect to the provided induction variable
+// (normally the PHI, but sometimes a multiply). A root increment is an
+// instruction, normally an add, with a positive constant less than Scale. In a
+// rerollable loop, each of these increments is the root of an instruction
+// graph isomorphic to the others. Also, we collect the final induction
+// increment (the increment equal to the Scale), and its users in LoopIncs.
+bool LoopReroll::collectAllRoots(Loop *L, uint64_t Inc, uint64_t Scale,
+ Instruction *IV,
+ SmallVector<SmallInstructionVector, 32> &Roots,
+ SmallInstructionSet &AllRoots,
+ SmallInstructionVector &LoopIncs) {
+ for (Value::use_iterator UI = IV->use_begin(),
+ UIE = IV->use_end(); UI != UIE; ++UI) {
+ Instruction *User = cast<Instruction>(*UI);
+ if (!SE->isSCEVable(User->getType()))
+ continue;
+ if (User->getType() != IV->getType())
+ continue;
+ if (!L->contains(User))
+ continue;
+ if (hasUsesOutsideLoop(User, L))
+ continue;
+
+ if (const SCEVConstant *Diff = dyn_cast<SCEVConstant>(SE->getMinusSCEV(
+ SE->getSCEV(User), SE->getSCEV(IV)))) {
+ uint64_t Idx = Diff->getValue()->getValue().getZExtValue();
+ if (Idx > 0 && Idx < Scale) {
+ Roots[Idx-1].push_back(User);
+ AllRoots.insert(User);
+ } else if (Idx == Scale && Inc > 1) {
+ LoopIncs.push_back(User);
+ }
+ }
+ }
+
+ if (Roots[0].empty())
+ return false;
+ bool AllSame = true;
+ for (unsigned i = 1; i < Scale-1; ++i)
+ if (Roots[i].size() != Roots[0].size()) {
+ AllSame = false;
+ break;
+ }
+
+ if (!AllSame)
+ return false;
+
+ return true;
+}
+
+// Validate the selected reductions. All iterations must have an isomorphic
+// part of the reduction chain and, for non-associative reductions, the chain
+// entries must appear in order.
+bool LoopReroll::ReductionTracker::validateSelected() {
+ // For a non-associative reduction, the chain entries must appear in order.
+ for (DenseSet<int>::iterator RI = Reds.begin(), RIE = Reds.end();
+ RI != RIE; ++RI) {
+ int i = *RI;
+ int PrevIter = 0, BaseCount = 0, Count = 0;
+ for (SimpleLoopReduction::iterator J = PossibleReds[i].begin(),
+ JE = PossibleReds[i].end(); J != JE; ++J) {
+ // Note that all instructions in the chain must have been found because
+ // all instructions in the function must have been assigned to some
+ // iteration.
+ int Iter = PossibleRedIter[*J];
+ if (Iter != PrevIter && Iter != PrevIter + 1 &&
+ !PossibleReds[i].getReducedValue()->isAssociative()) {
+ DEBUG(dbgs() << "LRR: Out-of-order non-associative reduction: " <<
+ *J << "\n");
+ return false;
+ }
+
+ if (Iter != PrevIter) {
+ if (Count != BaseCount) {
+ DEBUG(dbgs() << "LRR: Iteration " << PrevIter <<
+ " reduction use count " << Count <<
+ " is not equal to the base use count " <<
+ BaseCount << "\n");
+ return false;
+ }
+
+ Count = 0;
+ }
+
+ ++Count;
+ if (Iter == 0)
+ ++BaseCount;
+
+ PrevIter = Iter;
+ }
+ }
+
+ return true;
+}
+
+// For all selected reductions, remove all parts except those in the first
+// iteration (and the PHI). Replace outside uses of the reduced value with uses
+// of the first-iteration reduced value (in other words, reroll the selected
+// reductions).
+void LoopReroll::ReductionTracker::replaceSelected() {
+ // Fixup reductions to refer to the last instruction associated with the
+ // first iteration (not the last).
+ for (DenseSet<int>::iterator RI = Reds.begin(), RIE = Reds.end();
+ RI != RIE; ++RI) {
+ int i = *RI;
+ int j = 0;
+ for (int e = PossibleReds[i].size(); j != e; ++j)
+ if (PossibleRedIter[PossibleReds[i][j]] != 0) {
+ --j;
+ break;
+ }
+
+ // Replace users with the new end-of-chain value.
+ SmallInstructionVector Users;
+ for (Value::use_iterator UI =
+ PossibleReds[i].getReducedValue()->use_begin(),
+ UIE = PossibleReds[i].getReducedValue()->use_end(); UI != UIE; ++UI)
+ Users.push_back(cast<Instruction>(*UI));
+
+ for (SmallInstructionVector::iterator J = Users.begin(),
+ JE = Users.end(); J != JE; ++J)
+ (*J)->replaceUsesOfWith(PossibleReds[i].getReducedValue(),
+ PossibleReds[i][j]);
+ }
+}
+
+// Reroll the provided loop with respect to the provided induction variable.
+// Generally, we're looking for a loop like this:
+//
+// %iv = phi [ (preheader, ...), (body, %iv.next) ]
+// f(%iv)
+// %iv.1 = add %iv, 1 <-- a root increment
+// f(%iv.1)
+// %iv.2 = add %iv, 2 <-- a root increment
+// f(%iv.2)
+// %iv.scale_m_1 = add %iv, scale-1 <-- a root increment
+// f(%iv.scale_m_1)
+// ...
+// %iv.next = add %iv, scale
+// %cmp = icmp(%iv, ...)
+// br %cmp, header, exit
+//
+// Notably, we do not require that f(%iv), f(%iv.1), etc. be isolated groups of
+// instructions. In other words, the instructions in f(%iv), f(%iv.1), etc. can
+// be intermixed with eachother. The restriction imposed by this algorithm is
+// that the relative order of the isomorphic instructions in f(%iv), f(%iv.1),
+// etc. be the same.
+//
+// First, we collect the use set of %iv, excluding the other increment roots.
+// This gives us f(%iv). Then we iterate over the loop instructions (scale-1)
+// times, having collected the use set of f(%iv.(i+1)), during which we:
+// - Ensure that the next unmatched instruction in f(%iv) is isomorphic to
+// the next unmatched instruction in f(%iv.(i+1)).
+// - Ensure that both matched instructions don't have any external users
+// (with the exception of last-in-chain reduction instructions).
+// - Track the (aliasing) write set, and other side effects, of all
+// instructions that belong to future iterations that come before the matched
+// instructions. If the matched instructions read from that write set, then
+// f(%iv) or f(%iv.(i+1)) has some dependency on instructions in
+// f(%iv.(j+1)) for some j > i, and we cannot reroll the loop. Similarly,
+// if any of these future instructions had side effects (could not be
+// speculatively executed), and so do the matched instructions, when we
+// cannot reorder those side-effect-producing instructions, and rerolling
+// fails.
+//
+// Finally, we make sure that all loop instructions are either loop increment
+// roots, belong to simple latch code, parts of validated reductions, part of
+// f(%iv) or part of some f(%iv.i). If all of that is true (and all reductions
+// have been validated), then we reroll the loop.
+bool LoopReroll::reroll(Instruction *IV, Loop *L, BasicBlock *Header,
+ const SCEV *IterCount,
+ ReductionTracker &Reductions) {
+ const SCEVAddRecExpr *RealIVSCEV = cast<SCEVAddRecExpr>(SE->getSCEV(IV));
+ uint64_t Inc = cast<SCEVConstant>(RealIVSCEV->getOperand(1))->
+ getValue()->getZExtValue();
+ // The collection of loop increment instructions.
+ SmallInstructionVector LoopIncs;
+ uint64_t Scale = Inc;
+
+ // The effective induction variable, IV, is normally also the real induction
+ // variable. When we're dealing with a loop like:
+ // for (int i = 0; i < 500; ++i)
+ // x[3*i] = ...;
+ // x[3*i+1] = ...;
+ // x[3*i+2] = ...;
+ // then the real IV is still i, but the effective IV is (3*i).
+ Instruction *RealIV = IV;
+ if (Inc == 1 && !findScaleFromMul(RealIV, Scale, IV, LoopIncs))
+ return false;
+
+ assert(Scale <= MaxInc && "Scale is too large");
+ assert(Scale > 1 && "Scale must be at least 2");
+
+ // The set of increment instructions for each increment value.
+ SmallVector<SmallInstructionVector, 32> Roots(Scale-1);
+ SmallInstructionSet AllRoots;
+ if (!collectAllRoots(L, Inc, Scale, IV, Roots, AllRoots, LoopIncs))
+ return false;
+
+ DEBUG(dbgs() << "LRR: Found all root induction increments for: " <<
+ *RealIV << "\n");
+
+ // An array of just the possible reductions for this scale factor. When we
+ // collect the set of all users of some root instructions, these reduction
+ // instructions are treated as 'final' (their uses are not considered).
+ // This is important because we don't want the root use set to search down
+ // the reduction chain.
+ SmallInstructionSet PossibleRedSet;
+ SmallInstructionSet PossibleRedLastSet, PossibleRedPHISet;
+ Reductions.restrictToScale(Scale, PossibleRedSet, PossibleRedPHISet,
+ PossibleRedLastSet);
+
+ // We now need to check for equivalence of the use graph of each root with
+ // that of the primary induction variable (excluding the roots). Our goal
+ // here is not to solve the full graph isomorphism problem, but rather to
+ // catch common cases without a lot of work. As a result, we will assume
+ // that the relative order of the instructions in each unrolled iteration
+ // is the same (although we will not make an assumption about how the
+ // different iterations are intermixed). Note that while the order must be
+ // the same, the instructions may not be in the same basic block.
+ SmallInstructionSet Exclude(AllRoots);
+ Exclude.insert(LoopIncs.begin(), LoopIncs.end());
+
+ DenseSet<Instruction *> BaseUseSet;
+ collectInLoopUserSet(L, IV, Exclude, PossibleRedSet, BaseUseSet);
+
+ DenseSet<Instruction *> AllRootUses;
+ std::vector<DenseSet<Instruction *> > RootUseSets(Scale-1);
+
+ bool MatchFailed = false;
+ for (unsigned i = 0; i < Scale-1 && !MatchFailed; ++i) {
+ DenseSet<Instruction *> &RootUseSet = RootUseSets[i];
+ collectInLoopUserSet(L, Roots[i], SmallInstructionSet(),
+ PossibleRedSet, RootUseSet);
+
+ DEBUG(dbgs() << "LRR: base use set size: " << BaseUseSet.size() <<
+ " vs. iteration increment " << (i+1) <<
+ " use set size: " << RootUseSet.size() << "\n");
+
+ if (BaseUseSet.size() != RootUseSet.size()) {
+ MatchFailed = true;
+ break;
+ }
+
+ // In addition to regular aliasing information, we need to look for
+ // instructions from later (future) iterations that have side effects
+ // preventing us from reordering them past other instructions with side
+ // effects.
+ bool FutureSideEffects = false;
+ AliasSetTracker AST(*AA);
+
+ // The map between instructions in f(%iv.(i+1)) and f(%iv).
+ DenseMap<Value *, Value *> BaseMap;
+
+ assert(L->getNumBlocks() == 1 && "Cannot handle multi-block loops");
+ for (BasicBlock::iterator J1 = Header->begin(), J2 = Header->begin(),
+ JE = Header->end(); J1 != JE && !MatchFailed; ++J1) {
+ if (cast<Instruction>(J1) == RealIV)
+ continue;
+ if (cast<Instruction>(J1) == IV)
+ continue;
+ if (!BaseUseSet.count(J1))
+ continue;
+ if (PossibleRedPHISet.count(J1)) // Skip reduction PHIs.
+ continue;
+
+ while (J2 != JE && (!RootUseSet.count(J2) ||
+ std::find(Roots[i].begin(), Roots[i].end(), J2) !=
+ Roots[i].end())) {
+ // As we iterate through the instructions, instructions that don't
+ // belong to previous iterations (or the base case), must belong to
+ // future iterations. We want to track the alias set of writes from
+ // previous iterations.
+ if (!isa<PHINode>(J2) && !BaseUseSet.count(J2) &&
+ !AllRootUses.count(J2)) {
+ if (J2->mayWriteToMemory())
+ AST.add(J2);
+
+ // Note: This is specifically guarded by a check on isa<PHINode>,
+ // which while a valid (somewhat arbitrary) micro-optimization, is
+ // needed because otherwise isSafeToSpeculativelyExecute returns
+ // false on PHI nodes.
+ if (!isSimpleLoadStore(J2) && !isSafeToSpeculativelyExecute(J2, DL))
+ FutureSideEffects = true;
+ }
+
+ ++J2;
+ }
+
+ if (!J1->isSameOperationAs(J2)) {
+ DEBUG(dbgs() << "LRR: iteration root match failed at " << *J1 <<
+ " vs. " << *J2 << "\n");
+ MatchFailed = true;
+ break;
+ }
+
+ // Make sure that this instruction, which is in the use set of this
+ // root instruction, does not also belong to the base set or the set of
+ // some previous root instruction.
+ if (BaseUseSet.count(J2) || AllRootUses.count(J2)) {
+ DEBUG(dbgs() << "LRR: iteration root match failed at " << *J1 <<
+ " vs. " << *J2 << " (prev. case overlap)\n");
+ MatchFailed = true;
+ break;
+ }
+
+ // Make sure that we don't alias with any instruction in the alias set
+ // tracker. If we do, then we depend on a future iteration, and we
+ // can't reroll.
+ if (J2->mayReadFromMemory()) {
+ for (AliasSetTracker::iterator K = AST.begin(), KE = AST.end();
+ K != KE && !MatchFailed; ++K) {
+ if (K->aliasesUnknownInst(J2, *AA)) {
+ DEBUG(dbgs() << "LRR: iteration root match failed at " << *J1 <<
+ " vs. " << *J2 << " (depends on future store)\n");
+ MatchFailed = true;
+ break;
+ }
+ }
+ }
+
+ // If we've past an instruction from a future iteration that may have
+ // side effects, and this instruction might also, then we can't reorder
+ // them, and this matching fails. As an exception, we allow the alias
+ // set tracker to handle regular (simple) load/store dependencies.
+ if (FutureSideEffects &&
+ ((!isSimpleLoadStore(J1) && !isSafeToSpeculativelyExecute(J1)) ||
+ (!isSimpleLoadStore(J2) && !isSafeToSpeculativelyExecute(J2)))) {
+ DEBUG(dbgs() << "LRR: iteration root match failed at " << *J1 <<
+ " vs. " << *J2 <<
+ " (side effects prevent reordering)\n");
+ MatchFailed = true;
+ break;
+ }
+
+ // For instructions that are part of a reduction, if the operation is
+ // associative, then don't bother matching the operands (because we
+ // already know that the instructions are isomorphic, and the order
+ // within the iteration does not matter). For non-associative reductions,
+ // we do need to match the operands, because we need to reject
+ // out-of-order instructions within an iteration!
+ // For example (assume floating-point addition), we need to reject this:
+ // x += a[i]; x += b[i];
+ // x += a[i+1]; x += b[i+1];
+ // x += b[i+2]; x += a[i+2];
+ bool InReduction = Reductions.isPairInSame(J1, J2);
+
+ if (!(InReduction && J1->isAssociative())) {
+ bool Swapped = false, SomeOpMatched = false;;
+ for (unsigned j = 0; j < J1->getNumOperands() && !MatchFailed; ++j) {
+ Value *Op2 = J2->getOperand(j);
+
+ // If this is part of a reduction (and the operation is not
+ // associatve), then we match all operands, but not those that are
+ // part of the reduction.
+ if (InReduction)
+ if (Instruction *Op2I = dyn_cast<Instruction>(Op2))
+ if (Reductions.isPairInSame(J2, Op2I))
+ continue;
+
+ DenseMap<Value *, Value *>::iterator BMI = BaseMap.find(Op2);
+ if (BMI != BaseMap.end())
+ Op2 = BMI->second;
+ else if (std::find(Roots[i].begin(), Roots[i].end(),
+ (Instruction*) Op2) != Roots[i].end())
+ Op2 = IV;
+
+ if (J1->getOperand(Swapped ? unsigned(!j) : j) != Op2) {
+ // If we've not already decided to swap the matched operands, and
+ // we've not already matched our first operand (note that we could
+ // have skipped matching the first operand because it is part of a
+ // reduction above), and the instruction is commutative, then try
+ // the swapped match.
+ if (!Swapped && J1->isCommutative() && !SomeOpMatched &&
+ J1->getOperand(!j) == Op2) {
+ Swapped = true;
+ } else {
+ DEBUG(dbgs() << "LRR: iteration root match failed at " << *J1 <<
+ " vs. " << *J2 << " (operand " << j << ")\n");
+ MatchFailed = true;
+ break;
+ }
+ }
+
+ SomeOpMatched = true;
+ }
+ }
+
+ if ((!PossibleRedLastSet.count(J1) && hasUsesOutsideLoop(J1, L)) ||
+ (!PossibleRedLastSet.count(J2) && hasUsesOutsideLoop(J2, L))) {
+ DEBUG(dbgs() << "LRR: iteration root match failed at " << *J1 <<
+ " vs. " << *J2 << " (uses outside loop)\n");
+ MatchFailed = true;
+ break;
+ }
+
+ if (!MatchFailed)
+ BaseMap.insert(std::pair<Value *, Value *>(J2, J1));
+
+ AllRootUses.insert(J2);
+ Reductions.recordPair(J1, J2, i+1);
+
+ ++J2;
+ }
+ }
+
+ if (MatchFailed)
+ return false;
+
+ DEBUG(dbgs() << "LRR: Matched all iteration increments for " <<
+ *RealIV << "\n");
+
+ DenseSet<Instruction *> LoopIncUseSet;
+ collectInLoopUserSet(L, LoopIncs, SmallInstructionSet(),
+ SmallInstructionSet(), LoopIncUseSet);
+ DEBUG(dbgs() << "LRR: Loop increment set size: " <<
+ LoopIncUseSet.size() << "\n");
+
+ // Make sure that all instructions in the loop have been included in some
+ // use set.
+ for (BasicBlock::iterator J = Header->begin(), JE = Header->end();
+ J != JE; ++J) {
+ if (isa<DbgInfoIntrinsic>(J))
+ continue;
+ if (cast<Instruction>(J) == RealIV)
+ continue;
+ if (cast<Instruction>(J) == IV)
+ continue;
+ if (BaseUseSet.count(J) || AllRootUses.count(J) ||
+ (LoopIncUseSet.count(J) && (J->isTerminator() ||
+ isSafeToSpeculativelyExecute(J, DL))))
+ continue;
+
+ if (AllRoots.count(J))
+ continue;
+
+ if (Reductions.isSelectedPHI(J))
+ continue;
+
+ DEBUG(dbgs() << "LRR: aborting reroll based on " << *RealIV <<
+ " unprocessed instruction found: " << *J << "\n");
+ MatchFailed = true;
+ break;
+ }
+
+ if (MatchFailed)
+ return false;
+
+ DEBUG(dbgs() << "LRR: all instructions processed from " <<
+ *RealIV << "\n");
+
+ if (!Reductions.validateSelected())
+ return false;
+
+ // At this point, we've validated the rerolling, and we're committed to
+ // making changes!
+
+ Reductions.replaceSelected();
+
+ // Remove instructions associated with non-base iterations.
+ for (BasicBlock::reverse_iterator J = Header->rbegin();
+ J != Header->rend();) {
+ if (AllRootUses.count(&*J)) {
+ Instruction *D = &*J;
+ DEBUG(dbgs() << "LRR: removing: " << *D << "\n");
+ D->eraseFromParent();
+ continue;
+ }
+
+ ++J;
+ }
+
+ // Insert the new induction variable.
+ const SCEV *Start = RealIVSCEV->getStart();
+ if (Inc == 1)
+ Start = SE->getMulExpr(Start,
+ SE->getConstant(Start->getType(), Scale));
+ const SCEVAddRecExpr *H =
+ cast<SCEVAddRecExpr>(SE->getAddRecExpr(Start,
+ SE->getConstant(RealIVSCEV->getType(), 1),
+ L, SCEV::FlagAnyWrap));
+ { // Limit the lifetime of SCEVExpander.
+ SCEVExpander Expander(*SE, "reroll");
+ PHINode *NewIV =
+ cast<PHINode>(Expander.expandCodeFor(H, IV->getType(),
+ Header->begin()));
+ for (DenseSet<Instruction *>::iterator J = BaseUseSet.begin(),
+ JE = BaseUseSet.end(); J != JE; ++J)
+ (*J)->replaceUsesOfWith(IV, NewIV);
+
+ if (BranchInst *BI = dyn_cast<BranchInst>(Header->getTerminator())) {
+ if (LoopIncUseSet.count(BI)) {
+ const SCEV *ICSCEV = RealIVSCEV->evaluateAtIteration(IterCount, *SE);
+ if (Inc == 1)
+ ICSCEV =
+ SE->getMulExpr(ICSCEV, SE->getConstant(ICSCEV->getType(), Scale));
+ Value *IC;
+ if (isa<SCEVConstant>(ICSCEV)) {
+ IC = Expander.expandCodeFor(ICSCEV, NewIV->getType(), BI);
+ } else {
+ BasicBlock *Preheader = L->getLoopPreheader();
+ if (!Preheader)
+ Preheader = InsertPreheaderForLoop(L, this);
+
+ IC = Expander.expandCodeFor(ICSCEV, NewIV->getType(),
+ Preheader->getTerminator());
+ }
+
+ Value *NewIVNext = NewIV->getIncomingValueForBlock(Header);
+ Value *Cond = new ICmpInst(BI, CmpInst::ICMP_EQ, NewIVNext, IC,
+ "exitcond");
+ BI->setCondition(Cond);
+
+ if (BI->getSuccessor(1) != Header)
+ BI->swapSuccessors();
+ }
+ }
+ }
+
+ SimplifyInstructionsInBlock(Header, DL, TLI);
+ DeleteDeadPHIs(Header, TLI);
+ ++NumRerolledLoops;
+ return true;
+}
+
+bool LoopReroll::runOnLoop(Loop *L, LPPassManager &LPM) {
+ AA = &getAnalysis<AliasAnalysis>();
+ LI = &getAnalysis<LoopInfo>();
+ SE = &getAnalysis<ScalarEvolution>();
+ TLI = &getAnalysis<TargetLibraryInfo>();
+ DL = getAnalysisIfAvailable<DataLayout>();
+ DT = &getAnalysis<DominatorTree>();
+
+ BasicBlock *Header = L->getHeader();
+ DEBUG(dbgs() << "LRR: F[" << Header->getParent()->getName() <<
+ "] Loop %" << Header->getName() << " (" <<
+ L->getNumBlocks() << " block(s))\n");
+
+ bool Changed = false;
+
+ // For now, we'll handle only single BB loops.
+ if (L->getNumBlocks() > 1)
+ return Changed;
+
+ if (!SE->hasLoopInvariantBackedgeTakenCount(L))
+ return Changed;
+
+ const SCEV *LIBETC = SE->getBackedgeTakenCount(L);
+ const SCEV *IterCount =
+ SE->getAddExpr(LIBETC, SE->getConstant(LIBETC->getType(), 1));
+ DEBUG(dbgs() << "LRR: iteration count = " << *IterCount << "\n");
+
+ // First, we need to find the induction variable with respect to which we can
+ // reroll (there may be several possible options).
+ SmallInstructionVector PossibleIVs;
+ collectPossibleIVs(L, PossibleIVs);
+
+ if (PossibleIVs.empty()) {
+ DEBUG(dbgs() << "LRR: No possible IVs found\n");
+ return Changed;
+ }
+
+ ReductionTracker Reductions;
+ collectPossibleReductions(L, Reductions);
+
+ // For each possible IV, collect the associated possible set of 'root' nodes
+ // (i+1, i+2, etc.).
+ for (SmallInstructionVector::iterator I = PossibleIVs.begin(),
+ IE = PossibleIVs.end(); I != IE; ++I)
+ if (reroll(*I, L, Header, IterCount, Reductions)) {
+ Changed = true;
+ break;
+ }
+
+ return Changed;
+}
+
diff --git a/lib/Transforms/Scalar/Scalar.cpp b/lib/Transforms/Scalar/Scalar.cpp
index 72e00e170c..857597e474 100644
--- a/lib/Transforms/Scalar/Scalar.cpp
+++ b/lib/Transforms/Scalar/Scalar.cpp
@@ -44,6 +44,7 @@ void llvm::initializeScalarOpts(PassRegistry &Registry) {
initializeLoopInstSimplifyPass(Registry);
initializeLoopRotatePass(Registry);
initializeLoopStrengthReducePass(Registry);
+ initializeLoopRerollPass(Registry);
initializeLoopUnrollPass(Registry);
initializeLoopUnswitchPass(Registry);
initializeLoopIdiomRecognizePass(Registry);
@@ -112,6 +113,10 @@ void LLVMAddLoopRotatePass(LLVMPassManagerRef PM) {
unwrap(PM)->add(createLoopRotatePass());
}
+void LLVMAddLoopRerollPass(LLVMPassManagerRef PM) {
+ unwrap(PM)->add(createLoopRerollPass());
+}
+
void LLVMAddLoopUnrollPass(LLVMPassManagerRef PM) {
unwrap(PM)->add(createLoopUnrollPass());
}
diff --git a/test/Transforms/LoopReroll/basic.ll b/test/Transforms/LoopReroll/basic.ll
new file mode 100644
index 0000000000..314a14947e
--- /dev/null
+++ b/test/Transforms/LoopReroll/basic.ll
@@ -0,0 +1,327 @@
+; RUN: opt < %s -loop-reroll -S | FileCheck %s
+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"
+target triple = "x86_64-unknown-linux-gnu"
+
+; int foo(int a);
+; void bar(int *x) {
+; for (int i = 0; i < 500; i += 3) {
+; foo(i);
+; foo(i+1);
+; foo(i+2);
+; }
+; }
+
+; Function Attrs: nounwind uwtable
+define void @bar(i32* nocapture readnone %x) #0 {
+entry:
+ br label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %i.08 = phi i32 [ 0, %entry ], [ %add3, %for.body ]
+ %call = tail call i32 @foo(i32 %i.08) #1
+ %add = add nsw i32 %i.08, 1
+ %call1 = tail call i32 @foo(i32 %add) #1
+ %add2 = add nsw i32 %i.08, 2
+ %call3 = tail call i32 @foo(i32 %add2) #1
+ %add3 = add nsw i32 %i.08, 3
+ %exitcond = icmp eq i32 %add3, 500
+ br i1 %exitcond, label %for.end, label %for.body
+
+; CHECK-LABEL: @bar
+
+; CHECK: for.body:
+; CHECK: %indvar = phi i32 [ %indvar.next, %for.body ], [ 0, %entry ]
+; CHECK: %call = tail call i32 @foo(i32 %indvar) #1
+; CHECK: %indvar.next = add i32 %indvar, 1
+; CHECK: %exitcond1 = icmp eq i32 %indvar.next, 498
+; CHECK: br i1 %exitcond1, label %for.end, label %for.body
+
+; CHECK: ret
+
+for.end: ; preds = %for.body
+ ret void
+}
+
+declare i32 @foo(i32)
+
+; void hi1(int *x) {
+; for (int i = 0; i < 1500; i += 3) {
+; x[i] = foo(0);
+; x[i+1] = foo(0);
+; x[i+2] = foo(0);
+; }
+; }
+
+; Function Attrs: nounwind uwtable
+define void @hi1(i32* nocapture %x) #0 {
+entry:
+ br label %for.body
+
+for.body: ; preds = %entry, %for.body
+ %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+ %call = tail call i32 @foo(i32 0) #1
+ %arrayidx = getelementptr inbounds i32* %x, i64 %indvars.iv
+ store i32 %call, i32* %arrayidx, align 4
+ %call1 = tail call i32 @foo(i32 0) #1
+ %0 = add nsw i64 %indvars.iv, 1
+ %arrayidx3 = getelementptr inbounds i32* %x, i64 %0
+ store i32 %call1, i32* %arrayidx3, align 4
+ %call4 = tail call i32 @foo(i32 0) #1
+ %1 = add nsw i64 %indvars.iv, 2
+ %arrayidx7 = getelementptr inbounds i32* %x, i64 %1
+ store i32 %call4, i32* %arrayidx7, align 4
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 3
+ %2 = trunc i64 %indvars.iv.next to i32
+ %cmp = icmp slt i32 %2, 1500
+ br i1 %cmp, label %for.body, label %for.end
+
+; CHECK-LABEL: @hi1
+
+; CHECK: for.body:
+; CHECK: %indvar = phi i64 [ %indvar.next, %for.body ], [ 0, %entry ]
+; CHECK: %call = tail call i32 @foo(i32 0) #1
+; CHECK: %arrayidx = getelementptr inbounds i32* %x, i64 %indvar
+; CHECK: store i32 %call, i32* %arrayidx, align 4
+; CHECK: %indvar.next = add i64 %indvar, 1
+; CHECK: %exitcond = icmp eq i64 %indvar.next, 1500
+; CHECK: br i1 %exitcond, label %for.end, label %for.body
+
+; CHECK: ret
+
+for.end: ; preds = %for.body
+ ret void
+}
+
+; void hi2(int *x) {
+; for (int i = 0; i < 500; ++i) {
+; x[3*i] = foo(0);
+; x[3*i+1] = foo(0);
+; x[3*i+2] = foo(0);
+; }
+; }
+
+; Function Attrs: nounwind uwtable
+define void @hi2(i32* nocapture %x) #0 {
+entry:
+ br label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+ %call = tail call i32 @foo(i32 0) #1
+ %0 = mul nsw i64 %indvars.iv, 3
+ %arrayidx = getelementptr inbounds i32* %x, i64 %0
+ store i32 %call, i32* %arrayidx, align 4
+ %call1 = tail call i32 @foo(i32 0) #1
+ %1 = add nsw i64 %0, 1
+ %arrayidx4 = getelementptr inbounds i32* %x, i64 %1
+ store i32 %call1, i32* %arrayidx4, align 4
+ %call5 = tail call i32 @foo(i32 0) #1
+ %2 = add nsw i64 %0, 2
+ %arrayidx9 = getelementptr inbounds i32* %x, i64 %2
+ store i32 %call5, i32* %arrayidx9, align 4
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+ %exitcond = icmp eq i64 %indvars.iv.next, 500
+ br i1 %exitcond, label %for.end, label %for.body
+
+; CHECK-LABEL: @hi2
+
+; CHECK: for.body:
+; CHECK: %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+; CHECK: %call = tail call i32 @foo(i32 0) #1
+; CHECK: %arrayidx = getelementptr inbounds i32* %x, i64 %indvars.iv
+; CHECK: store i32 %call, i32* %arrayidx, align 4
+; CHECK: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+; CHECK: %exitcond1 = icmp eq i64 %indvars.iv.next, 1500
+; CHECK: br i1 %exitcond1, label %for.end, label %for.body
+
+; CHECK: ret
+
+for.end: ; preds = %for.body
+ ret void
+}
+
+; void goo(float alpha, float *a, float *b) {
+; for (int i = 0; i < 3200; i += 5) {
+; a[i] += alpha * b[i];
+; a[i + 1] += alpha * b[i + 1];
+; a[i + 2] += alpha * b[i + 2];
+; a[i + 3] += alpha * b[i + 3];
+; a[i + 4] += alpha * b[i + 4];
+; }
+; }
+
+; Function Attrs: nounwind uwtable
+define void @goo(float %alpha, float* nocapture %a, float* nocapture readonly %b) #0 {
+entry:
+ br label %for.body
+
+for.body: ; preds = %entry, %for.body
+ %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+ %arrayidx = getelementptr inbounds float* %b, i64 %indvars.iv
+ %0 = load float* %arrayidx, align 4
+ %mul = fmul float %0, %alpha
+ %arrayidx2 = getelementptr inbounds float* %a, i64 %indvars.iv
+ %1 = load float* %arrayidx2, align 4
+ %add = fadd float %1, %mul
+ store float %add, float* %arrayidx2, align 4
+ %2 = add nsw i64 %indvars.iv, 1
+ %arrayidx5 = getelementptr inbounds float* %b, i64 %2
+ %3 = load float* %arrayidx5, align 4
+ %mul6 = fmul float %3, %alpha
+ %arrayidx9 = getelementptr inbounds float* %a, i64 %2
+ %4 = load float* %arrayidx9, align 4
+ %add10 = fadd float %4, %mul6
+ store float %add10, float* %arrayidx9, align 4
+ %5 = add nsw i64 %indvars.iv, 2
+ %arrayidx13 = getelementptr inbounds float* %b, i64 %5
+ %6 = load float* %arrayidx13, align 4
+ %mul14 = fmul float %6, %alpha
+ %arrayidx17 = getelementptr inbounds float* %a, i64 %5
+ %7 = load float* %arrayidx17, align 4
+ %add18 = fadd float %7, %mul14
+ store float %add18, float* %arrayidx17, align 4
+ %8 = add nsw i64 %indvars.iv, 3
+ %arrayidx21 = getelementptr inbounds float* %b, i64 %8
+ %9 = load float* %arrayidx21, align 4
+ %mul22 = fmul float %9, %alpha
+ %arrayidx25 = getelementptr inbounds float* %a, i64 %8
+ %10 = load float* %arrayidx25, align 4
+ %add26 = fadd float %10, %mul22
+ store float %add26, float* %arrayidx25, align 4
+ %11 = add nsw i64 %indvars.iv, 4
+ %arrayidx29 = getelementptr inbounds float* %b, i64 %11
+ %12 = load float* %arrayidx29, align 4
+ %mul30 = fmul float %12, %alpha
+ %arrayidx33 = getelementptr inbounds float* %a, i64 %11
+ %13 = load float* %arrayidx33, align 4
+ %add34 = fadd float %13, %mul30
+ store float %add34, float* %arrayidx33, align 4
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 5
+ %14 = trunc i64 %indvars.iv.next to i32
+ %cmp = icmp slt i32 %14, 3200
+ br i1 %cmp, label %for.body, label %for.end
+
+; CHECK-LABEL: @goo
+
+; CHECK: for.body:
+; CHECK: %indvar = phi i64 [ %indvar.next, %for.body ], [ 0, %entry ]
+; CHECK: %arrayidx = getelementptr inbounds float* %b, i64 %indvar
+; CHECK: %0 = load float* %arrayidx, align 4
+; CHECK: %mul = fmul float %0, %alpha
+; CHECK: %arrayidx2 = getelementptr inbounds float* %a, i64 %indvar
+; CHECK: %1 = load float* %arrayidx2, align 4
+; CHECK: %add = fadd float %1, %mul
+; CHECK: store float %add, float* %arrayidx2, align 4
+; CHECK: %indvar.next = add i64 %indvar, 1
+; CHECK: %exitcond = icmp eq i64 %indvar.next, 3200
+; CHECK: br i1 %exitcond, label %for.end, label %for.body
+
+; CHECK: ret
+
+for.end: ; preds = %for.body
+ ret void
+}
+
+; void hoo(float alpha, float *a, float *b, int *ip) {
+; for (int i = 0; i < 3200; i += 5) {
+; a[i] += alpha * b[ip[i]];
+; a[i + 1] += alpha * b[ip[i + 1]];
+; a[i + 2] += alpha * b[ip[i + 2]];
+; a[i + 3] += alpha * b[ip[i + 3]];
+; a[i + 4] += alpha * b[ip[i + 4]];
+; }
+; }
+
+; Function Attrs: nounwind uwtable
+define void @hoo(float %alpha, float* nocapture %a, float* nocapture readonly %b, i32* nocapture readonly %ip) #0 {
+entry:
+ br label %for.body
+
+for.body: ; preds = %entry, %for.body
+ %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+ %arrayidx = getelementptr inbounds i32* %ip, i64 %indvars.iv
+ %0 = load i32* %arrayidx, align 4
+ %idxprom1 = sext i32 %0 to i64
+ %arrayidx2 = getelementptr inbounds float* %b, i64 %idxprom1
+ %1 = load float* %arrayidx2, align 4
+ %mul = fmul float %1, %alpha
+ %arrayidx4 = getelementptr inbounds float* %a, i64 %indvars.iv
+ %2 = load float* %arrayidx4, align 4
+ %add = fadd float %2, %mul
+ store float %add, float* %arrayidx4, align 4
+ %3 = add nsw i64 %indvars.iv, 1
+ %arrayidx7 = getelementptr inbounds i32* %ip, i64 %3
+ %4 = load i32* %arrayidx7, align 4
+ %idxprom8 = sext i32 %4 to i64
+ %arrayidx9 = getelementptr inbounds float* %b, i64 %idxprom8
+ %5 = load float* %arrayidx9, align 4
+ %mul10 = fmul float %5, %alpha
+ %arrayidx13 = getelementptr inbounds float* %a, i64 %3
+ %6 = load float* %arrayidx13, align 4
+ %add14 = fadd float %6, %mul10
+ store float %add14, float* %arrayidx13, align 4
+ %7 = add nsw i64 %indvars.iv, 2
+ %arrayidx17 = getelementptr inbounds i32* %ip, i64 %7
+ %8 = load i32* %arrayidx17, align 4
+ %idxprom18 = sext i32 %8 to i64
+ %arrayidx19 = getelementptr inbounds float* %b, i64 %idxprom18
+ %9 = load float* %arrayidx19, align 4
+ %mul20 = fmul float %9, %alpha
+ %arrayidx23 = getelementptr inbounds float* %a, i64 %7
+ %10 = load float* %arrayidx23, align 4
+ %add24 = fadd float %10, %mul20
+ store float %add24, float* %arrayidx23, align 4
+ %11 = add nsw i64 %indvars.iv, 3
+ %arrayidx27 = getelementptr inbounds i32* %ip, i64 %11
+ %12 = load i32* %arrayidx27, align 4
+ %idxprom28 = sext i32 %12 to i64
+ %arrayidx29 = getelementptr inbounds float* %b, i64 %idxprom28
+ %13 = load float* %arrayidx29, align 4
+ %mul30 = fmul float %13, %alpha
+ %arrayidx33 = getelementptr inbounds float* %a, i64 %11
+ %14 = load float* %arrayidx33, align 4
+ %add34 = fadd float %14, %mul30
+ store float %add34, float* %arrayidx33, align 4
+ %15 = add nsw i64 %indvars.iv, 4
+ %arrayidx37 = getelementptr inbounds i32* %ip, i64 %15
+ %16 = load i32* %arrayidx37, align 4
+ %idxprom38 = sext i32 %16 to i64
+ %arrayidx39 = getelementptr inbounds float* %b, i64 %idxprom38
+ %17 = load float* %arrayidx39, align 4
+ %mul40 = fmul float %17, %alpha
+ %arrayidx43 = getelementptr inbounds float* %a, i64 %15
+ %18 = load float* %arrayidx43, align 4
+ %add44 = fadd float %18, %mul40
+ store float %add44, float* %arrayidx43, align 4
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 5
+ %19 = trunc i64 %indvars.iv.next to i32
+ %cmp = icmp slt i32 %19, 3200
+ br i1 %cmp, label %for.body, label %for.end
+
+; CHECK-LABEL: @hoo
+
+; CHECK: for.body:
+; CHECK: %indvar = phi i64 [ %indvar.next, %for.body ], [ 0, %entry ]
+; CHECK: %arrayidx = getelementptr inbounds i32* %ip, i64 %indvar
+; CHECK: %0 = load i32* %arrayidx, align 4
+; CHECK: %idxprom1 = sext i32 %0 to i64
+; CHECK: %arrayidx2 = getelementptr inbounds float* %b, i64 %idxprom1
+; CHECK: %1 = load float* %arrayidx2, align 4
+; CHECK: %mul = fmul float %1, %alpha
+; CHECK: %arrayidx4 = getelementptr inbounds float* %a, i64 %indvar
+; CHECK: %2 = load float* %arrayidx4, align 4
+; CHECK: %add = fadd float %2, %mul
+; CHECK: store float %add, float* %arrayidx4, align 4
+; CHECK: %indvar.next = add i64 %indvar, 1
+; CHECK: %exitcond = icmp eq i64 %indvar.next, 3200
+; CHECK: br i1 %exitcond, label %for.end, label %for.body
+
+; CHECK: ret
+
+for.end: ; preds = %for.body
+ ret void
+}
+
+attributes #0 = { nounwind uwtable }
+attributes #1 = { nounwind }
+
diff --git a/test/Transforms/LoopReroll/reduction.ll b/test/Transforms/LoopReroll/reduction.ll
new file mode 100644
index 0000000000..aed7670b66
--- /dev/null
+++ b/test/Transforms/LoopReroll/reduction.ll
@@ -0,0 +1,96 @@
+; RUN: opt < %s -loop-reroll -S | FileCheck %s
+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"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @foo(i32* nocapture readonly %x) #0 {
+entry:
+ br label %for.body
+
+for.body: ; preds = %entry, %for.body
+ %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+ %r.029 = phi i32 [ 0, %entry ], [ %add12, %for.body ]
+ %arrayidx = getelementptr inbounds i32* %x, i64 %indvars.iv
+ %0 = load i32* %arrayidx, align 4
+ %add = add nsw i32 %0, %r.029
+ %1 = or i64 %indvars.iv, 1
+ %arrayidx3 = getelementptr inbounds i32* %x, i64 %1
+ %2 = load i32* %arrayidx3, align 4
+ %add4 = add nsw i32 %add, %2
+ %3 = or i64 %indvars.iv, 2
+ %arrayidx7 = getelementptr inbounds i32* %x, i64 %3
+ %4 = load i32* %arrayidx7, align 4
+ %add8 = add nsw i32 %add4, %4
+ %5 = or i64 %indvars.iv, 3
+ %arrayidx11 = getelementptr inbounds i32* %x, i64 %5
+ %6 = load i32* %arrayidx11, align 4
+ %add12 = add nsw i32 %add8, %6
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 4
+ %7 = trunc i64 %indvars.iv.next to i32
+ %cmp = icmp slt i32 %7, 400
+ br i1 %cmp, label %for.body, label %for.end
+
+; CHECK-LABEL: @foo
+
+; CHECK: for.body:
+; CHECK: %indvar = phi i64 [ %indvar.next, %for.body ], [ 0, %entry ]
+; CHECK: %r.029 = phi i32 [ 0, %entry ], [ %add, %for.body ]
+; CHECK: %arrayidx = getelementptr inbounds i32* %x, i64 %indvar
+; CHECK: %0 = load i32* %arrayidx, align 4
+; CHECK: %add = add nsw i32 %0, %r.029
+; CHECK: %indvar.next = add i64 %indvar, 1
+; CHECK: %exitcond = icmp eq i64 %indvar.next, 400
+; CHECK: br i1 %exitcond, label %for.end, label %for.body
+
+; CHECK: ret
+
+for.end: ; preds = %for.body
+ ret i32 %add12
+}
+
+define float @bar(float* nocapture readonly %x) #0 {
+entry:
+ br label %for.body
+
+for.body: ; preds = %entry, %for.body
+ %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+ %r.029 = phi float [ 0.0, %entry ], [ %add12, %for.body ]
+ %arrayidx = getelementptr inbounds float* %x, i64 %indvars.iv
+ %0 = load float* %arrayidx, align 4
+ %add = fadd float %0, %r.029
+ %1 = or i64 %indvars.iv, 1
+ %arrayidx3 = getelementptr inbounds float* %x, i64 %1
+ %2 = load float* %arrayidx3, align 4
+ %add4 = fadd float %add, %2
+ %3 = or i64 %indvars.iv, 2
+ %arrayidx7 = getelementptr inbounds float* %x, i64 %3
+ %4 = load float* %arrayidx7, align 4
+ %add8 = fadd float %add4, %4
+ %5 = or i64 %indvars.iv, 3
+ %arrayidx11 = getelementptr inbounds float* %x, i64 %5
+ %6 = load float* %arrayidx11, align 4
+ %add12 = fadd float %add8, %6
+ %indvars.iv.next = add nuw nsw i64 %indvars.iv, 4
+ %7 = trunc i64 %indvars.iv.next to i32
+ %cmp = icmp slt i32 %7, 400
+ br i1 %cmp, label %for.body, label %for.end
+
+; CHECK-LABEL: @bar
+
+; CHECK: for.body:
+; CHECK: %indvar = phi i64 [ %indvar.next, %for.body ], [ 0, %entry ]
+; CHECK: %r.029 = phi float [ 0.000000e+00, %entry ], [ %add, %for.body ]
+; CHECK: %arrayidx = getelementptr inbounds float* %x, i64 %indvar
+; CHECK: %0 = load float* %arrayidx, align 4
+; CHECK: %add = fadd float %0, %r.029
+; CHECK: %indvar.next = add i64 %indvar, 1
+; CHECK: %exitcond = icmp eq i64 %indvar.next, 400
+; CHECK: br i1 %exitcond, label %for.end, label %for.body
+
+; CHECK: ret
+
+for.end: ; preds = %for.body
+ ret float %add12
+}
+
+attributes #0 = { nounwind readonly uwtable }
+
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-23 17:18:40 +0000