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Add -unroll-runtime for unrolling loops with run-time trip counts.

Browse Source 
Patch by Brendon Cahoon!

This extends the existing LoopUnroll and LoopUnrollPass. Brendon
measured no regressions in the llvm test suite with -unroll-runtime
enabled. This implementation works by using the existing loop
unrolling code to unroll the loop by a power-of-two (default 8). It
generates an if-then-else sequence of code prior to the loop to
execute the extra iterations before entering the unrolled loop.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146245 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2011-12-09 06:19:40 +00:00
parent 9c181a92d8
commit 5d73448bb7
9 changed files with 644 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/llvm/Transforms/Utils/UnrollLoop.h
View File

@ -22,9 +22,12 @@ class Loop;
class LoopInfo;
class LPPassManager;
bool UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
bool UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, bool AllowRuntime,
unsigned TripMultiple, LoopInfo* LI, LPPassManager* LPM);
bool UnrollRuntimeLoopProlog(Loop *L, unsigned Count, LoopInfo *LI,
LPPassManager* LPM);
}
#endif

35
lib/Transforms/Scalar/LoopUnrollPass.cpp
View File

@ -40,6 +40,10 @@ UnrollAllowPartial("unroll-allow-partial", cl::init(false), cl::Hidden,
cl::desc("Allows loops to be partially unrolled until "
"-unroll-threshold loop size is reached."));
static cl::opt<bool>
UnrollRuntime("unroll-runtime", cl::ZeroOrMore, cl::init(false), cl::Hidden,
cl::desc("Unroll loops with run-time trip counts"));
namespace {
class LoopUnroll : public LoopPass {
public:
@ -63,6 +67,10 @@ namespace {
// explicit -unroll-threshold).
static const unsigned OptSizeUnrollThreshold = 50;
// Default unroll count for loops with run-time trip count if
// -unroll-count is not set
static const unsigned UnrollRuntimeCount = 8;
unsigned CurrentCount;
unsigned CurrentThreshold;
bool CurrentAllowPartial;
@ -151,8 +159,13 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
TripCount = SE->getSmallConstantTripCount(L, LatchBlock);
TripMultiple = SE->getSmallConstantTripMultiple(L, LatchBlock);
}
// Automatically select an unroll count.
// Use a default unroll-count if the user doesn't specify a value
// and the trip count is a run-time value. The default is different
// for run-time or compile-time trip count loops.
unsigned Count = CurrentCount;
if (UnrollRuntime && CurrentCount == 0 && TripCount == 0)
Count = UnrollRuntimeCount;
if (Count == 0) {
// Conservative heuristic: if we know the trip count, see if we can
// completely unroll (subject to the threshold, checked below); otherwise
@ -177,15 +190,23 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
if (TripCount != 1 && Size > Threshold) {
DEBUG(dbgs() << " Too large to fully unroll with count: " << Count
<< " because size: " << Size << ">" << Threshold << "\n");
if (!CurrentAllowPartial) {
if (!CurrentAllowPartial && !(UnrollRuntime && TripCount == 0)) {
DEBUG(dbgs() << " will not try to unroll partially because "
<< "-unroll-allow-partial not given\n");
return false;
}
// Reduce unroll count to be modulo of TripCount for partial unrolling
Count = Threshold / LoopSize;
while (Count != 0 && TripCount%Count != 0) {
Count--;
if (TripCount) {
// Reduce unroll count to be modulo of TripCount for partial unrolling
Count = CurrentThreshold / LoopSize;
while (Count != 0 && TripCount%Count != 0)
Count--;
}
else if (UnrollRuntime) {
// Reduce unroll count to be a lower power-of-two value
while (Count != 0 && Size > CurrentThreshold) {
Count >>= 1;
Size = LoopSize*Count;
}
}
if (Count < 2) {
DEBUG(dbgs() << " could not unroll partially\n");
@ -196,7 +217,7 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
}
// Unroll the loop.
if (!UnrollLoop(L, Count, TripCount, TripMultiple, LI, &LPM))
if (!UnrollLoop(L, Count, TripCount, UnrollRuntime, TripMultiple, LI, &LPM))
return false;
return true;

1
lib/Transforms/Utils/CMakeLists.txt
View File

@ -14,6 +14,7 @@ add_llvm_library(LLVMTransformUtils
Local.cpp
LoopSimplify.cpp
LoopUnroll.cpp
LoopUnrollRuntime.cpp
LowerExpectIntrinsic.cpp
LowerInvoke.cpp
LowerSwitch.cpp

29
lib/Transforms/Utils/LoopUnroll.cpp
View File

@ -135,7 +135,8 @@ static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI,
/// This utility preserves LoopInfo. If DominatorTree or ScalarEvolution are
/// available it must also preserve those analyses.
bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
unsigned TripMultiple, LoopInfo *LI, LPPassManager *LPM) {
bool AllowRuntime, unsigned TripMultiple,
LoopInfo *LI, LPPassManager *LPM) {
BasicBlock *Preheader = L->getLoopPreheader();
if (!Preheader) {
DEBUG(dbgs() << " Can't unroll; loop preheader-insertion failed.\n");
@ -165,12 +166,6 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
return false;
}
// Notify ScalarEvolution that the loop will be substantially changed,
// if not outright eliminated.
ScalarEvolution *SE = LPM->getAnalysisIfAvailable<ScalarEvolution>();
if (SE)
SE->forgetLoop(L);
if (TripCount != 0)
DEBUG(dbgs() << " Trip Count = " << TripCount << "\n");
if (TripMultiple != 1)
@ -188,6 +183,20 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
// Are we eliminating the loop control altogether?
bool CompletelyUnroll = Count == TripCount;
// We assume a run-time trip count if the compiler cannot
// figure out the loop trip count and the unroll-runtime
// flag is specified.
bool RuntimeTripCount = (TripCount == 0 && Count > 0 && AllowRuntime);
if (RuntimeTripCount && !UnrollRuntimeLoopProlog(L, Count, LI, LPM))
return false;
// Notify ScalarEvolution that the loop will be substantially changed,
// if not outright eliminated.
ScalarEvolution *SE = LPM->getAnalysisIfAvailable<ScalarEvolution>();
if (SE)
SE->forgetLoop(L);
// If we know the trip count, we know the multiple...
unsigned BreakoutTrip = 0;
if (TripCount != 0) {
@ -209,6 +218,8 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
DEBUG(dbgs() << " with a breakout at trip " << BreakoutTrip);
} else if (TripMultiple != 1) {
DEBUG(dbgs() << " with " << TripMultiple << " trips per branch");
} else if (RuntimeTripCount) {
DEBUG(dbgs() << " with run-time trip count");
}
DEBUG(dbgs() << "!\n");
}
@ -332,6 +343,10 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
BasicBlock *Dest = Headers[j];
bool NeedConditional = true;
if (RuntimeTripCount && j != 0) {
NeedConditional = false;
}
// For a complete unroll, make the last iteration end with a branch
// to the exit block.
if (CompletelyUnroll && j == 0) {

375
lib/Transforms/Utils/LoopUnrollRuntime.cpp Normal file
View File

@ -0,0 +1,375 @@
//===-- UnrollLoopRuntime.cpp - Runtime Loop unrolling utilities ----------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements some loop unrolling utilities for loops with run-time
// trip counts. See LoopUnroll.cpp for unrolling loops with compile-time
// trip counts.
//
// The functions in this file are used to generate extra code when the
// run-time trip count modulo the unroll factor is not 0. When this is the
// case, we need to generate code to execute these 'left over' iterations.
//
// The current strategy generates an if-then-else sequence prior to the
// unrolled loop to execute the 'left over' iterations. Other strategies
// include generate a loop before or after the unrolled loop.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "loop-unroll"
#include "llvm/Transforms/Utils/UnrollLoop.h"
#include "llvm/BasicBlock.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/LoopIterator.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include <algorithm>
using namespace llvm;
STATISTIC(NumRuntimeUnrolled,
"Number of loops unrolled with run-time trip counts");
/// Connect the unrolling prolog code to the original loop.
/// The unrolling prolog code contains code to execute the
/// 'extra' iterations if the run-time trip count modulo the
/// unroll count is non-zero.
///
/// This function performs the following:
/// - Create PHI nodes at prolog end block to combine values
/// that exit the prolog code and jump around the prolog.
/// - Add a PHI operand to a PHI node at the loop exit block
/// for values that exit the prolog and go around the loop.
/// - Branch around the original loop if the trip count is less
/// than the unroll factor.
///
static void ConnectProlog(Loop *L, Value *TripCount, unsigned Count,
BasicBlock *LastPrologBB, BasicBlock *PrologEnd,
BasicBlock *OrigPH, BasicBlock *NewPH,
ValueToValueMapTy &LVMap, Pass *P) {
BasicBlock *Latch = L->getLoopLatch();
assert(Latch != 0 && "Loop must have a latch");
// Create a PHI node for each outgoing value from the original loop
// (which means it is an outgoing value from the prolog code too).
// The new PHI node is inserted in the prolog end basic block.
// The new PHI name is added as an operand of a PHI node in either
// the loop header or the loop exit block.
for (succ_iterator SBI = succ_begin(Latch), SBE = succ_end(Latch);
SBI != SBE; ++SBI) {
for (BasicBlock::iterator BBI = (*SBI)->begin();
PHINode *PN = dyn_cast<PHINode>(BBI); ++BBI) {
// Add a new PHI node to the prolog end block and add the
// appropriate incoming values.
PHINode *NewPN = PHINode::Create(PN->getType(), 2, PN->getName()+".unr",
PrologEnd->getTerminator());
// Adding a value to the new PHI node from the original loop preheader.
// This is the value that skips all the prolog code.
if (L->contains(PN)) {
NewPN->addIncoming(PN->getIncomingValueForBlock(NewPH), OrigPH);
} else {
NewPN->addIncoming(Constant::getNullValue(PN->getType()), OrigPH);
}
Value *OrigVal = PN->getIncomingValueForBlock(Latch);
Value *V = OrigVal;
if (Instruction *I = dyn_cast<Instruction>(V)) {
if (L->contains(I)) {
V = LVMap[I];
}
}
// Adding a value to the new PHI node from the last prolog block
// that was created.
NewPN->addIncoming(V, LastPrologBB);
// Update the existing PHI node operand with the value from the
// new PHI node. How this is done depends on if the existing
// PHI node is in the original loop block, or the exit block.
if (L->contains(PN)) {
PN->setIncomingValue(PN->getBasicBlockIndex(NewPH), NewPN);
} else {
PN->addIncoming(NewPN, PrologEnd);
}
}
}
// Create a branch around the orignal loop, which is taken if the
// trip count is less than the unroll factor.
Instruction *InsertPt = PrologEnd->getTerminator();
Instruction *BrLoopExit =
new ICmpInst(InsertPt, ICmpInst::ICMP_ULT, TripCount,
ConstantInt::get(TripCount->getType(), Count));
BasicBlock *Exit = L->getUniqueExitBlock();
assert(Exit != 0 && "Loop must have a single exit block only");
// Split the exit to maintain loop canonicalization guarantees
SmallVector<BasicBlock*, 4> Preds(pred_begin(Exit), pred_end(Exit));
if (!Exit->isLandingPad()) {
SplitBlockPredecessors(Exit, Preds.data(), Preds.size(),
".unr-lcssa", P);
} else {
SmallVector<BasicBlock*, 2> NewBBs;
SplitLandingPadPredecessors(Exit, Preds, ".unr1-lcssa", ".unr2-lcssa",
P, NewBBs);
}
// Add the branch to the exit block (around the unrolled loop)
BranchInst::Create(Exit, NewPH, BrLoopExit, InsertPt);
InsertPt->eraseFromParent();
}
/// Create a clone of the blocks in a loop and connect them together.
/// This function doesn't create a clone of the loop structure.
///
/// There are two value maps that are defined and used. VMap is
/// for the values in the current loop instance. LVMap contains
/// the values from the last loop instance. We need the LVMap values
/// to update the inital values for the current loop instance.
///
static void CloneLoopBlocks(Loop *L,
bool FirstCopy,
BasicBlock *InsertTop,
BasicBlock *InsertBot,
std::vector<BasicBlock *> &NewBlocks,
LoopBlocksDFS &LoopBlocks,
ValueToValueMapTy &VMap,
ValueToValueMapTy &LVMap,
LoopInfo *LI) {
BasicBlock *Preheader = L->getLoopPreheader();
BasicBlock *Header = L->getHeader();
BasicBlock *Latch = L->getLoopLatch();
Function *F = Header->getParent();
LoopBlocksDFS::RPOIterator BlockBegin = LoopBlocks.beginRPO();
LoopBlocksDFS::RPOIterator BlockEnd = LoopBlocks.endRPO();
// For each block in the original loop, create a new copy,
// and update the value map with the newly created values.
for (LoopBlocksDFS::RPOIterator BB = BlockBegin; BB != BlockEnd; ++BB) {
BasicBlock *NewBB = CloneBasicBlock(*BB, VMap, ".unr", F);
NewBlocks.push_back(NewBB);
if (Loop *ParentLoop = L->getParentLoop())
ParentLoop->addBasicBlockToLoop(NewBB, LI->getBase());
VMap[*BB] = NewBB;
if (Header == *BB) {
// For the first block, add a CFG connection to this newly
// created block
InsertTop->getTerminator()->setSuccessor(0, NewBB);
// Change the incoming values to the ones defined in the
// previously cloned loop.
for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) {
PHINode *NewPHI = cast<PHINode>(VMap[I]);
if (FirstCopy) {
// We replace the first phi node with the value from the preheader
VMap[I] = NewPHI->getIncomingValueForBlock(Preheader);
NewBB->getInstList().erase(NewPHI);
} else {
// Update VMap with values from the previous block
unsigned idx = NewPHI->getBasicBlockIndex(Latch);
Value *InVal = NewPHI->getIncomingValue(idx);
if (Instruction *I = dyn_cast<Instruction>(InVal))
if (L->contains(I))
InVal = LVMap[InVal];
NewPHI->setIncomingValue(idx, InVal);
NewPHI->setIncomingBlock(idx, InsertTop);
}
}
}
if (Latch == *BB) {
VMap.erase((*BB)->getTerminator());
NewBB->getTerminator()->eraseFromParent();
BranchInst::Create(InsertBot, NewBB);
}
}
// LastValueMap is updated with the values for the current loop
// which are used the next time this function is called.
for (ValueToValueMapTy::iterator VI = VMap.begin(), VE = VMap.end();
VI != VE; ++VI) {
LVMap[VI->first] = VI->second;
}
}
/// Insert code in the prolog code when unrolling a loop with a
/// run-time trip-count.
///
/// This method assumes that the loop unroll factor is total number
/// of loop bodes in the loop after unrolling. (Some folks refer
/// to the unroll factor as the number of *extra* copies added).
/// We assume also that the loop unroll factor is a power-of-two. So, after
/// unrolling the loop, the number of loop bodies executed is 2,
/// 4, 8, etc. Note - LLVM converts the if-then-sequence to a switch
/// instruction in SimplifyCFG.cpp. Then, the backend decides how code for
/// the switch instruction is generated.
///
/// extraiters = tripcount % loopfactor
/// if (extraiters == 0) jump Loop:
/// if (extraiters == loopfactor) jump L1
/// if (extraiters == loopfactor-1) jump L2
/// ...
/// L1: LoopBody;
/// L2: LoopBody;
/// ...
/// if tripcount < loopfactor jump End
/// Loop:
/// ...
/// End:
///
bool llvm::UnrollRuntimeLoopProlog(Loop *L, unsigned Count, LoopInfo *LI,
LPPassManager *LPM) {
// for now, only unroll loops that contain a single exit
SmallVector<BasicBlock*, 4> ExitingBlocks;
L->getExitingBlocks(ExitingBlocks);
if (ExitingBlocks.size() > 1)
return false;
// Make sure the loop is in canonical form, and there is a single
// exit block only.
if (!L->isLoopSimplifyForm() || L->getUniqueExitBlock() == 0)
return false;
// Use Scalar Evolution to compute the trip count. This allows more
// loops to be unrolled than relying on induction var simplification
ScalarEvolution *SE = LPM->getAnalysisIfAvailable<ScalarEvolution>();
if (SE == 0)
return false;
// Only unroll loops with a computable trip count and the trip count needs
// to be an int value (allowing a pointer type is a TODO item)
const SCEV *BECount = SE->getBackedgeTakenCount(L);
if (isa<SCEVCouldNotCompute>(BECount) || !BECount->getType()->isIntegerTy())
return false;
// Add 1 since the backedge count doesn't include the first loop iteration
const SCEV *TripCountSC =
SE->getAddExpr(BECount, SE->getConstant(BECount->getType(), 1));
if (isa<SCEVCouldNotCompute>(TripCountSC))
return false;
// We only handle cases when the unroll factor is a power of 2.
// Count is the loop unroll factor, the number of extra copies added + 1.
if ((Count & (Count-1)) != 0)
return false;
// If this loop is nested, then the loop unroller changes the code in
// parent loop, so the Scalar Evolution pass needs to be run again
if (Loop *ParentLoop = L->getParentLoop())
SE->forgetLoop(ParentLoop);
BasicBlock *PH = L->getLoopPreheader();
BasicBlock *Header = L->getHeader();
BasicBlock *Latch = L->getLoopLatch();
// It helps to splits the original preheader twice, one for the end of the
// prolog code and one for a new loop preheader
BasicBlock *PEnd = SplitEdge(PH, Header, LPM->getAsPass());
BasicBlock *NewPH = SplitBlock(PEnd, PEnd->getTerminator(), LPM->getAsPass());
BranchInst *PreHeaderBR = cast<BranchInst>(PH->getTerminator());
// Compute the number of extra iterations required, which is:
// extra iterations = run-time trip count % (loop unroll factor + 1)
SCEVExpander Expander(*SE, "loop-unroll");
Value *TripCount = Expander.expandCodeFor(TripCountSC, TripCountSC->getType(),
PreHeaderBR);
Type *CountTy = TripCount->getType();
BinaryOperator *ModVal =
BinaryOperator::CreateURem(TripCount,
ConstantInt::get(CountTy, Count),
"xtraiter");
ModVal->insertBefore(PreHeaderBR);
// Check if for no extra iterations, then jump to unrolled loop
Value *BranchVal = new ICmpInst(PreHeaderBR,
ICmpInst::ICMP_NE, ModVal,
ConstantInt::get(CountTy, 0), "lcmp");
// Branch to either the extra iterations or the unrolled loop
// We will fix up the true branch label when adding loop body copies
BranchInst::Create(PEnd, PEnd, BranchVal, PreHeaderBR);
assert(PreHeaderBR->isUnconditional() &&
PreHeaderBR->getSuccessor(0) == PEnd &&
"CFG edges in Preheader are not correct");
PreHeaderBR->eraseFromParent();
ValueToValueMapTy LVMap;
Function *F = Header->getParent();
// These variables are used to update the CFG links in each iteration
BasicBlock *CompareBB = 0;
BasicBlock *LastLoopBB = PH;
// Get an ordered list of blocks in the loop to help with the ordering of the
// cloned blocks in the prolog code
LoopBlocksDFS LoopBlocks(L);
LoopBlocks.perform(LI);
//
// For each extra loop iteration, create a copy of the loop's basic blocks
// and generate a condition that branches to the copy depending on the
// number of 'left over' iterations.
//
for (unsigned leftOverIters = Count-1; leftOverIters > 0; --leftOverIters) {
std::vector<BasicBlock*> NewBlocks;
ValueToValueMapTy VMap;
// Clone all the basic blocks in the loop, but we don't clone the loop
// This function adds the appropriate CFG connections.
CloneLoopBlocks(L, (leftOverIters == Count-1), LastLoopBB, PEnd, NewBlocks,
LoopBlocks, VMap, LVMap, LI);
LastLoopBB = cast<BasicBlock>(VMap[Latch]);
// Insert the cloned blocks into function just before the original loop
F->getBasicBlockList().splice(PEnd, F->getBasicBlockList(),
NewBlocks[0], F->end());
// Generate the code for the comparison which determines if the loop
// prolog code needs to be executed.
if (leftOverIters == Count-1) {
// There is no compare block for the fall-thru case when for the last
// left over iteration
CompareBB = NewBlocks[0];
} else {
// Create a new block for the comparison
BasicBlock *NewBB = BasicBlock::Create(CompareBB->getContext(), "unr.cmp",
F, CompareBB);
if (Loop *ParentLoop = L->getParentLoop()) {
// Add the new block to the parent loop, if needed
ParentLoop->addBasicBlockToLoop(NewBB, LI->getBase());
}
// The comparison w/ the extra iteration value and branch
Value *BranchVal = new ICmpInst(*NewBB, ICmpInst::ICMP_EQ, ModVal,
ConstantInt::get(CountTy, leftOverIters),
"un.tmp");
// Branch to either the extra iterations or the unrolled loop
BranchInst::Create(NewBlocks[0], CompareBB,
BranchVal, NewBB);
CompareBB = NewBB;
PH->getTerminator()->setSuccessor(0, NewBB);
VMap[NewPH] = CompareBB;
}
// Rewrite the cloned instruction operands to use the values
// created when the clone is created.
for (unsigned i = 0, e = NewBlocks.size(); i != e; ++i) {
for (BasicBlock::iterator I = NewBlocks[i]->begin(),
E = NewBlocks[i]->end(); I != E; ++I) {
RemapInstruction(I, VMap,
RF_NoModuleLevelChanges|RF_IgnoreMissingEntries);
}
}
}
// Connect the prolog code to the original loop and update the
// PHI functions.
ConnectProlog(L, TripCount, Count, LastLoopBB, PEnd, PH, NewPH, LVMap,
LPM->getAsPass());
NumRuntimeUnrolled++;
return true;
}

109
test/Transforms/LoopUnroll/runtime-loop.ll Normal file
View File

@ -0,0 +1,109 @@
; RUN: opt < %s -S -loop-unroll -unroll-runtime=true | FileCheck %s
; Tests for unrolling loops with run-time trip counts
; CHECK: unr.cmp{{.*}}:
; CHECK: for.body.unr{{.*}}:
; CHECK: for.body:
; CHECK: br i1 %exitcond.7, label %for.end.loopexit{{.*}}, label %for.body
define i32 @test(i32* nocapture %a, i32 %n) nounwind uwtable readonly {
entry:
%cmp1 = icmp eq i32 %n, 0
br i1 %cmp1, label %for.end, label %for.body
for.body: ; preds = %for.body, %entry
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
%sum.02 = phi i32 [ %add, %for.body ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i32* %a, i64 %indvars.iv
%0 = load i32* %arrayidx, align 4
%add = add nsw i32 %0, %sum.02
%indvars.iv.next = add i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %n
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
%sum.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.body ]
ret i32 %sum.0.lcssa
}
; Still try to completely unroll loops with compile-time trip counts
; even if the -unroll-runtime is specified
; CHECK: for.body:
; CHECK-NOT: for.body.unr:
define i32 @test1(i32* nocapture %a) nounwind uwtable readonly {
entry:
br label %for.body
for.body: ; preds = %for.body, %entry
%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
%sum.01 = phi i32 [ 0, %entry ], [ %add, %for.body ]
%arrayidx = getelementptr inbounds i32* %a, i64 %indvars.iv
%0 = load i32* %arrayidx, align 4
%add = add nsw i32 %0, %sum.01
%indvars.iv.next = add i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, 5
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret i32 %add
}
; This is test 2007-05-09-UnknownTripCount.ll which can be unrolled now
; if the -unroll-runtime option is turned on
; CHECK: bb72.2:
define void @foo(i32 %trips) {
entry:
br label %cond_true.outer
cond_true.outer:
%indvar1.ph = phi i32 [ 0, %entry ], [ %indvar.next2, %bb72 ]
br label %bb72
bb72:
%indvar.next2 = add i32 %indvar1.ph, 1
%exitcond3 = icmp eq i32 %indvar.next2, %trips
br i1 %exitcond3, label %cond_true138, label %cond_true.outer
cond_true138:
ret void
}
; Test run-time unrolling for a loop that counts down by -2.
; CHECK: for.body.unr:
; CHECK: br i1 %cmp.7, label %for.cond.for.end_crit_edge{{.*}}, label %for.body
define zeroext i16 @down(i16* nocapture %p, i32 %len) nounwind uwtable readonly {
entry:
%cmp2 = icmp eq i32 %len, 0
br i1 %cmp2, label %for.end, label %for.body
for.body: ; preds = %for.body, %entry
%p.addr.05 = phi i16* [ %incdec.ptr, %for.body ], [ %p, %entry ]
%len.addr.04 = phi i32 [ %sub, %for.body ], [ %len, %entry ]
%res.03 = phi i32 [ %add, %for.body ], [ 0, %entry ]
%incdec.ptr = getelementptr inbounds i16* %p.addr.05, i64 1
%0 = load i16* %p.addr.05, align 2
%conv = zext i16 %0 to i32
%add = add i32 %conv, %res.03
%sub = add nsw i32 %len.addr.04, -2
%cmp = icmp eq i32 %sub, 0
br i1 %cmp, label %for.cond.for.end_crit_edge, label %for.body
for.cond.for.end_crit_edge: ; preds = %for.body
%phitmp = trunc i32 %add to i16
br label %for.end
for.end: ; preds = %for.cond.for.end_crit_edge, %entry
%res.0.lcssa = phi i16 [ %phitmp, %for.cond.for.end_crit_edge ], [ 0, %entry ]
ret i16 %res.0.lcssa
}

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; RUN: opt < %s -S -loop-unroll -unroll-runtime -unroll-count=4 | FileCheck %s
; This tests that setting the unroll count works
; CHECK: unr.cmp:
; CHECK: for.body.unr:
; CHECK: for.body:
; CHECK: br i1 %exitcond.3, label %for.end.loopexit{{.*}}, label %for.body
; CHECK-NOT: br i1 %exitcond.4, label %for.end.loopexit{{.*}}, label %for.body
define i32 @test(i32* nocapture %a, i32 %n) nounwind uwtable readonly {
entry:
%cmp1 = icmp eq i32 %n, 0
br i1 %cmp1, label %for.end, label %for.body
for.body: ; preds = %for.body, %entry
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
%sum.02 = phi i32 [ %add, %for.body ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i32* %a, i64 %indvars.iv
%0 = load i32* %arrayidx, align 4
%add = add nsw i32 %0, %sum.02
%indvars.iv.next = add i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %n
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
%sum.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.body ]
ret i32 %sum.0.lcssa
}

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; RUN: opt < %s -S -loop-unroll -unroll-threshold=50 -unroll-runtime -unroll-count=8 | FileCheck %s
; Choose a smaller, power-of-two, unroll count if the loop is too large.
; This test makes sure we're not unrolling 'odd' counts
; CHECK: unr.cmp:
; CHECK: for.body.unr:
; CHECK: for.body:
; CHECK: br i1 %exitcond.3, label %for.end.loopexit{{.*}}, label %for.body
; CHECK-NOT: br i1 %exitcond.4, label %for.end.loopexit{{.*}}, label %for.body
define i32 @test(i32* nocapture %a, i32 %n) nounwind uwtable readonly {
entry:
%cmp1 = icmp eq i32 %n, 0
br i1 %cmp1, label %for.end, label %for.body
for.body: ; preds = %for.body, %entry
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
%sum.02 = phi i32 [ %add, %for.body ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i32* %a, i64 %indvars.iv
%0 = load i32* %arrayidx, align 4
%add = add nsw i32 %0, %sum.02
%indvars.iv.next = add i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %n
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
%sum.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.body ]
ret i32 %sum.0.lcssa
}

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; RUN: opt < %s -disable-output -stats -loop-unroll -unroll-runtime -unroll-threshold=400 -info-output-file - | FileCheck %s --check-prefix=STATS
; Test that nested loops can be unrolled. We need to increase threshold to do it
; STATS: 2 loop-unroll - Number of loops unrolled (completely or otherwise)
define i32 @nested(i32* nocapture %a, i32 %n, i32 %m) nounwind uwtable readonly {
entry:
%cmp11 = icmp sgt i32 %n, 0
br i1 %cmp11, label %for.cond1.preheader.lr.ph, label %for.end7
for.cond1.preheader.lr.ph: ; preds = %entry
%cmp28 = icmp sgt i32 %m, 0
br label %for.cond1.preheader
for.cond1.preheader: ; preds = %for.inc5, %for.cond1.preheader.lr.ph
%indvars.iv16 = phi i64 [ 0, %for.cond1.preheader.lr.ph ], [ %indvars.iv.next17, %for.inc5 ]
%sum.012 = phi i32 [ 0, %for.cond1.preheader.lr.ph ], [ %sum.1.lcssa, %for.inc5 ]
br i1 %cmp28, label %for.body3, label %for.inc5
for.body3: ; preds = %for.cond1.preheader, %for.body3
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body3 ], [ 0, %for.cond1.preheader ]
%sum.19 = phi i32 [ %add4, %for.body3 ], [ %sum.012, %for.cond1.preheader ]
%0 = add nsw i64 %indvars.iv, %indvars.iv16
%arrayidx = getelementptr inbounds i32* %a, i64 %0
%1 = load i32* %arrayidx, align 4
%add4 = add nsw i32 %1, %sum.19
%indvars.iv.next = add i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %m
br i1 %exitcond, label %for.inc5, label %for.body3
for.inc5: ; preds = %for.body3, %for.cond1.preheader
%sum.1.lcssa = phi i32 [ %sum.012, %for.cond1.preheader ], [ %add4, %for.body3 ]
%indvars.iv.next17 = add i64 %indvars.iv16, 1
%lftr.wideiv18 = trunc i64 %indvars.iv.next17 to i32
%exitcond19 = icmp eq i32 %lftr.wideiv18, %n
br i1 %exitcond19, label %for.end7, label %for.cond1.preheader
for.end7: ; preds = %for.inc5, %entry
%sum.0.lcssa = phi i32 [ 0, %entry ], [ %sum.1.lcssa, %for.inc5 ]
ret i32 %sum.0.lcssa
}