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LoopRotate: Convert the methods of LoopRotate to utility functions. NFC

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This moves the actual work to do loop rotation into standalone
functions with the analysis results they need passed in as arguments,
leaving the class itself as a relatively simple shim. This will make
the functions easy to reuse when we're ready to port this
transformation to the new pass manager.

llvm-svn: 255574
This commit is contained in:
Justin Bogner 2015-12-14 23:22:48 +00:00
parent 8f1642f744
commit 5881fcfc6b
1 changed files with 82 additions and 79 deletions
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161
lib/Transforms/Scalar/LoopRotation.cpp
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@ -45,65 +45,6 @@ DefaultRotationThreshold("rotation-max-header-size", cl::init(16), cl::Hidden,
cl::desc("The default maximum header size for automatic loop rotation"));
STATISTIC(NumRotated, "Number of loops rotated");
namespace {
class LoopRotate : public LoopPass {
public:
static char ID; // Pass ID, replacement for typeid
LoopRotate(int SpecifiedMaxHeaderSize = -1) : LoopPass(ID) {
initializeLoopRotatePass(*PassRegistry::getPassRegistry());
if (SpecifiedMaxHeaderSize == -1)
MaxHeaderSize = DefaultRotationThreshold;
else
MaxHeaderSize = unsigned(SpecifiedMaxHeaderSize);
}
// LCSSA form makes instruction renaming easier.
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addPreserved<AAResultsWrapperPass>();
AU.addRequired<AssumptionCacheTracker>();
AU.addPreserved<DominatorTreeWrapperPass>();
AU.addRequired<LoopInfoWrapperPass>();
AU.addPreserved<LoopInfoWrapperPass>();
AU.addRequiredID(LoopSimplifyID);
AU.addPreservedID(LoopSimplifyID);
AU.addRequiredID(LCSSAID);
AU.addPreservedID(LCSSAID);
AU.addPreserved<ScalarEvolutionWrapperPass>();
AU.addPreserved<SCEVAAWrapperPass>();
AU.addRequired<TargetTransformInfoWrapperPass>();
AU.addPreserved<BasicAAWrapperPass>();
AU.addPreserved<GlobalsAAWrapperPass>();
}
bool runOnLoop(Loop *L, LPPassManager &LPM) override;
bool simplifyLoopLatch(Loop *L);
bool rotateLoop(Loop *L, bool SimplifiedLatch);
private:
unsigned MaxHeaderSize;
LoopInfo *LI;
const TargetTransformInfo *TTI;
AssumptionCache *AC;
DominatorTree *DT;
};
}
char LoopRotate::ID = 0;
INITIALIZE_PASS_BEGIN(LoopRotate, "loop-rotate", "Rotate Loops", false, false)
INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
INITIALIZE_PASS_DEPENDENCY(LCSSA)
INITIALIZE_PASS_DEPENDENCY(SCEVAAWrapperPass)
INITIALIZE_PASS_DEPENDENCY(BasicAAWrapperPass)
INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass)
INITIALIZE_PASS_END(LoopRotate, "loop-rotate", "Rotate Loops", false, false)
Pass *llvm::createLoopRotatePass(int MaxHeaderSize) {
return new LoopRotate(MaxHeaderSize);
}
/// RewriteUsesOfClonedInstructions - We just cloned the instructions from the
/// old header into the preheader. If there were uses of the values produced by
@ -180,7 +121,10 @@ static void RewriteUsesOfClonedInstructions(BasicBlock *OrigHeader,
/// rotation. LoopRotate should be repeatable and converge to a canonical
/// form. This property is satisfied because simplifying the loop latch can only
/// happen once across multiple invocations of the LoopRotate pass.
bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
static bool rotateLoop(Loop *L, unsigned MaxHeaderSize, LoopInfo *LI,
const TargetTransformInfo *TTI, AssumptionCache *AC,
DominatorTree *DT, ScalarEvolution *SE,
bool SimplifiedLatch) {
// If the loop has only one block then there is not much to rotate.
if (L->getBlocks().size() == 1)
return false;
@ -235,8 +179,8 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
// Anything ScalarEvolution may know about this loop or the PHI nodes
// in its header will soon be invalidated.
if (auto *SEWP = getAnalysisIfAvailable<ScalarEvolutionWrapperPass>())
SEWP->getSE().forgetLoop(L);
if (SE)
SE->forgetLoop(L);
DEBUG(dbgs() << "LoopRotation: rotating "; L->dump());
@ -538,7 +482,7 @@ static bool shouldSpeculateInstrs(BasicBlock::iterator Begin,
/// canonical form so downstream passes can handle it.
///
/// I don't believe this invalidates SCEV.
bool LoopRotate::simplifyLoopLatch(Loop *L) {
static bool simplifyLoopLatch(Loop *L, LoopInfo *LI, DominatorTree *DT) {
BasicBlock *Latch = L->getLoopLatch();
if (!Latch || Latch->hasAddressTaken())
return false;
@ -583,31 +527,23 @@ bool LoopRotate::simplifyLoopLatch(Loop *L) {
return true;
}
/// Rotate Loop L as many times as possible. Return true if
/// the loop is rotated at least once.
bool LoopRotate::runOnLoop(Loop *L, LPPassManager &LPM) {
if (skipOptnoneFunction(L))
return false;
/// Rotate \c L as many times as possible. Return true if the loop is rotated
/// at least once.
static bool iterativelyRotateLoop(Loop *L, unsigned MaxHeaderSize, LoopInfo *LI,
const TargetTransformInfo *TTI,
AssumptionCache *AC, DominatorTree *DT,
ScalarEvolution *SE) {
// Save the loop metadata.
MDNode *LoopMD = L->getLoopID();
Function &F = *L->getHeader()->getParent();
LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
auto *DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>();
DT = DTWP ? &DTWP->getDomTree() : nullptr;
// Simplify the loop latch before attempting to rotate the header
// upward. Rotation may not be needed if the loop tail can be folded into the
// loop exit.
bool SimplifiedLatch = simplifyLoopLatch(L);
bool SimplifiedLatch = simplifyLoopLatch(L, LI, DT);
// One loop can be rotated multiple times.
bool MadeChange = false;
while (rotateLoop(L, SimplifiedLatch)) {
while (rotateLoop(L, MaxHeaderSize, LI, TTI, AC, DT, SE, SimplifiedLatch)) {
MadeChange = true;
SimplifiedLatch = false;
}
@ -619,3 +555,70 @@ bool LoopRotate::runOnLoop(Loop *L, LPPassManager &LPM) {
return MadeChange;
}
namespace {
class LoopRotate : public LoopPass {
unsigned MaxHeaderSize;
public:
static char ID; // Pass ID, replacement for typeid
LoopRotate(int SpecifiedMaxHeaderSize = -1) : LoopPass(ID) {
initializeLoopRotatePass(*PassRegistry::getPassRegistry());
if (SpecifiedMaxHeaderSize == -1)
MaxHeaderSize = DefaultRotationThreshold;
else
MaxHeaderSize = unsigned(SpecifiedMaxHeaderSize);
}
// LCSSA form makes instruction renaming easier.
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addPreserved<AAResultsWrapperPass>();
AU.addRequired<AssumptionCacheTracker>();
AU.addPreserved<DominatorTreeWrapperPass>();
AU.addRequired<LoopInfoWrapperPass>();
AU.addPreserved<LoopInfoWrapperPass>();
AU.addRequiredID(LoopSimplifyID);
AU.addPreservedID(LoopSimplifyID);
AU.addRequiredID(LCSSAID);
AU.addPreservedID(LCSSAID);
AU.addPreserved<ScalarEvolutionWrapperPass>();
AU.addPreserved<SCEVAAWrapperPass>();
AU.addRequired<TargetTransformInfoWrapperPass>();
AU.addPreserved<BasicAAWrapperPass>();
AU.addPreserved<GlobalsAAWrapperPass>();
}
bool runOnLoop(Loop *L, LPPassManager &LPM) override {
if (skipOptnoneFunction(L))
return false;
Function &F = *L->getHeader()->getParent();
auto *LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
const auto *TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
auto *AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
auto *DTWP = getAnalysisIfAvailable<DominatorTreeWrapperPass>();
auto *DT = DTWP ? &DTWP->getDomTree() : nullptr;
auto *SEWP = getAnalysisIfAvailable<ScalarEvolutionWrapperPass>();
auto *SE = SEWP ? &SEWP->getSE() : nullptr;
return iterativelyRotateLoop(L, MaxHeaderSize, LI, TTI, AC, DT, SE);
}
};
}
char LoopRotate::ID = 0;
INITIALIZE_PASS_BEGIN(LoopRotate, "loop-rotate", "Rotate Loops", false, false)
INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
INITIALIZE_PASS_DEPENDENCY(LCSSA)
INITIALIZE_PASS_DEPENDENCY(SCEVAAWrapperPass)
INITIALIZE_PASS_DEPENDENCY(BasicAAWrapperPass)
INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass)
INITIALIZE_PASS_END(LoopRotate, "loop-rotate", "Rotate Loops", false, false)
Pass *llvm::createLoopRotatePass(int MaxHeaderSize) {
return new LoopRotate(MaxHeaderSize);
}