//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "loop-unswitch"
#include "llvm/Transforms/Scalar.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/CodeMetrics.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Module.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <set>
using namespace llvm;
+#define DEBUG_TYPE "loop-unswitch"
+
STATISTIC(NumBranches, "Number of branches unswitched");
STATISTIC(NumSwitches, "Number of switches unswitched");
STATISTIC(NumSelects , "Number of selects unswitched");
public:
LUAnalysisCache() :
- CurLoopInstructions(0), CurrentLoopProperties(0),
+ CurLoopInstructions(nullptr), CurrentLoopProperties(nullptr),
MaxSize(Threshold)
{}
// Analyze loop. Check its size, calculate is it possible to unswitch
// it. Returns true if we can unswitch this loop.
- bool countLoop(const Loop *L, const TargetTransformInfo &TTI);
+ bool countLoop(const Loop *L, const TargetTransformInfo &TTI,
+ AssumptionCache *AC);
// Clean all data related to given loop.
void forgetLoop(const Loop *L);
class LoopUnswitch : public LoopPass {
LoopInfo *LI; // Loop information
LPPassManager *LPM;
+ AssumptionCache *AC;
// LoopProcessWorklist - Used to check if second loop needs processing
// after RewriteLoopBodyWithConditionConstant rewrites first loop.
static char ID; // Pass ID, replacement for typeid
explicit LoopUnswitch(bool Os = false) :
LoopPass(ID), OptimizeForSize(Os), redoLoop(false),
- currentLoop(0), DT(0), loopHeader(0),
- loopPreheader(0) {
+ currentLoop(nullptr), DT(nullptr), loopHeader(nullptr),
+ loopPreheader(nullptr) {
initializeLoopUnswitchPass(*PassRegistry::getPassRegistry());
}
/// loop preheaders be inserted into the CFG.
///
void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequired<AssumptionCacheTracker>();
AU.addRequiredID(LoopSimplifyID);
AU.addPreservedID(LoopSimplifyID);
- AU.addRequired<LoopInfo>();
- AU.addPreserved<LoopInfo>();
+ AU.addRequired<LoopInfoWrapperPass>();
+ AU.addPreserved<LoopInfoWrapperPass>();
AU.addRequiredID(LCSSAID);
AU.addPreservedID(LCSSAID);
AU.addPreserved<DominatorTreeWrapperPass>();
AU.addPreserved<ScalarEvolution>();
- AU.addRequired<TargetTransformInfo>();
+ AU.addRequired<TargetTransformInfoWrapperPass>();
}
private:
BranchesInfo.forgetLoop(currentLoop);
}
- /// RemoveLoopFromWorklist - If the specified loop is on the loop worklist,
- /// remove it.
- void RemoveLoopFromWorklist(Loop *L) {
- std::vector<Loop*>::iterator I = std::find(LoopProcessWorklist.begin(),
- LoopProcessWorklist.end(), L);
- if (I != LoopProcessWorklist.end())
- LoopProcessWorklist.erase(I);
- }
-
void initLoopData() {
loopHeader = currentLoop->getHeader();
loopPreheader = currentLoop->getLoopPreheader();
Instruction *InsertPt);
void SimplifyCode(std::vector<Instruction*> &Worklist, Loop *L);
- void RemoveLoopFromHierarchy(Loop *L);
- bool IsTrivialUnswitchCondition(Value *Cond, Constant **Val = 0,
- BasicBlock **LoopExit = 0);
+ bool IsTrivialUnswitchCondition(Value *Cond, Constant **Val = nullptr,
+ BasicBlock **LoopExit = nullptr);
};
}
// Analyze loop. Check its size, calculate is it possible to unswitch
// it. Returns true if we can unswitch this loop.
-bool LUAnalysisCache::countLoop(const Loop *L, const TargetTransformInfo &TTI) {
+bool LUAnalysisCache::countLoop(const Loop *L, const TargetTransformInfo &TTI,
+ AssumptionCache *AC) {
LoopPropsMapIt PropsIt;
bool Inserted;
// large numbers of branches which cause loop unswitching to go crazy.
// This is a very ad-hoc heuristic.
+ SmallPtrSet<const Value *, 32> EphValues;
+ CodeMetrics::collectEphemeralValues(L, AC, EphValues);
+
// FIXME: This is overly conservative because it does not take into
// consideration code simplification opportunities and code that can
// be shared by the resultant unswitched loops.
CodeMetrics Metrics;
for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
I != E; ++I)
- Metrics.analyzeBasicBlock(*I, TTI);
+ Metrics.analyzeBasicBlock(*I, TTI, EphValues);
Props.SizeEstimation = std::min(Metrics.NumInsts, Metrics.NumBlocks * 5);
Props.CanBeUnswitchedCount = MaxSize / (Props.SizeEstimation);
LoopsProperties.erase(LIt);
}
- CurrentLoopProperties = 0;
- CurLoopInstructions = 0;
+ CurrentLoopProperties = nullptr;
+ CurLoopInstructions = nullptr;
}
// Mark case value as unswitched.
char LoopUnswitch::ID = 0;
INITIALIZE_PASS_BEGIN(LoopUnswitch, "loop-unswitch", "Unswitch loops",
false, false)
-INITIALIZE_AG_DEPENDENCY(TargetTransformInfo)
+INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
-INITIALIZE_PASS_DEPENDENCY(LoopInfo)
+INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LCSSA)
INITIALIZE_PASS_END(LoopUnswitch, "loop-unswitch", "Unswitch loops",
false, false)
// We can never unswitch on vector conditions.
if (Cond->getType()->isVectorTy())
- return 0;
+ return nullptr;
// Constants should be folded, not unswitched on!
- if (isa<Constant>(Cond)) return 0;
+ if (isa<Constant>(Cond)) return nullptr;
// TODO: Handle: br (VARIANT|INVARIANT).
return RHS;
}
- return 0;
+ return nullptr;
}
bool LoopUnswitch::runOnLoop(Loop *L, LPPassManager &LPM_Ref) {
if (skipOptnoneFunction(L))
return false;
- LI = &getAnalysis<LoopInfo>();
+ AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(
+ *L->getHeader()->getParent());
+ LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
LPM = &LPM_Ref;
DominatorTreeWrapperPass *DTWP =
getAnalysisIfAvailable<DominatorTreeWrapperPass>();
- DT = DTWP ? &DTWP->getDomTree() : 0;
+ DT = DTWP ? &DTWP->getDomTree() : nullptr;
currentLoop = L;
Function *F = currentLoop->getHeader()->getParent();
bool Changed = false;
// Probably we reach the quota of branches for this loop. If so
// stop unswitching.
- if (!BranchesInfo.countLoop(currentLoop, getAnalysis<TargetTransformInfo>()))
+ if (!BranchesInfo.countLoop(
+ currentLoop, getAnalysis<TargetTransformInfoWrapperPass>().getTTI(
+ *currentLoop->getHeader()->getParent()),
+ AC))
return false;
// Loop over all of the basic blocks in the loop. If we find an interior
// Find a value to unswitch on:
// FIXME: this should chose the most expensive case!
// FIXME: scan for a case with a non-critical edge?
- Constant *UnswitchVal = 0;
+ Constant *UnswitchVal = nullptr;
// Do not process same value again and again.
// At this point we have some cases already unswitched and
if (!L->contains(BB)) {
// Otherwise, this is a loop exit, this is fine so long as this is the
// first exit.
- if (ExitBB != 0) return false;
+ if (ExitBB) return false;
ExitBB = BB;
return true;
}
static BasicBlock *isTrivialLoopExitBlock(Loop *L, BasicBlock *BB) {
std::set<BasicBlock*> Visited;
Visited.insert(L->getHeader()); // Branches to header make infinite loops.
- BasicBlock *ExitBB = 0;
+ BasicBlock *ExitBB = nullptr;
if (isTrivialLoopExitBlockHelper(L, BB, ExitBB, Visited))
return ExitBB;
- return 0;
+ return nullptr;
}
/// IsTrivialUnswitchCondition - Check to see if this unswitch condition is
TerminatorInst *HeaderTerm = Header->getTerminator();
LLVMContext &Context = Header->getContext();
- BasicBlock *LoopExitBB = 0;
+ BasicBlock *LoopExitBB = nullptr;
if (BranchInst *BI = dyn_cast<BranchInst>(HeaderTerm)) {
// If the header block doesn't end with a conditional branch on Cond, we
// can't handle it.
/// unswitch the loop, reprocess the pieces, then return true.
bool LoopUnswitch::UnswitchIfProfitable(Value *LoopCond, Constant *Val) {
Function *F = loopHeader->getParent();
- Constant *CondVal = 0;
- BasicBlock *ExitBlock = 0;
+ Constant *CondVal = nullptr;
+ BasicBlock *ExitBlock = nullptr;
if (IsTrivialUnswitchCondition(LoopCond, &CondVal, &ExitBlock)) {
// If the condition is trivial, always unswitch. There is no code growth
// Check to see if it would be profitable to unswitch current loop.
// Do not do non-trivial unswitch while optimizing for size.
- if (OptimizeForSize ||
- F->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
- Attribute::OptimizeForSize))
+ if (OptimizeForSize || F->hasFnAttribute(Attribute::OptimizeForSize))
return false;
UnswitchNontrivialCondition(LoopCond, Val, currentLoop);
for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
I != E; ++I)
if (LI->getLoopFor(*I) == L)
- New->addBasicBlockToLoop(cast<BasicBlock>(VM[*I]), LI->getBase());
+ New->addBasicBlockToLoop(cast<BasicBlock>(VM[*I]), *LI);
// Add all of the subloops to the new loop.
for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
// If either edge is critical, split it. This helps preserve LoopSimplify
// form for enclosing loops.
- SplitCriticalEdge(BI, 0, this, false, false, true);
- SplitCriticalEdge(BI, 1, this, false, false, true);
+ auto Options = CriticalEdgeSplittingOptions(DT, LI).setPreserveLCSSA();
+ SplitCriticalEdge(BI, 0, Options);
+ SplitCriticalEdge(BI, 1, Options);
}
/// UnswitchTrivialCondition - Given a loop that has a trivial unswitchable
// First step, split the preheader, so that we know that there is a safe place
// to insert the conditional branch. We will change loopPreheader to have a
// conditional branch on Cond.
- BasicBlock *NewPH = SplitEdge(loopPreheader, loopHeader, this);
+ BasicBlock *NewPH = SplitEdge(loopPreheader, loopHeader, DT, LI);
// Now that we have a place to insert the conditional branch, create a place
// to branch to: this is the exit block out of the loop that we should
// without actually branching to it (the exit block should be dominated by the
// loop header, not the preheader).
assert(!L->contains(ExitBlock) && "Exit block is in the loop?");
- BasicBlock *NewExit = SplitBlock(ExitBlock, ExitBlock->begin(), this);
+ BasicBlock *NewExit = SplitBlock(ExitBlock, ExitBlock->begin(), DT, LI);
// Okay, now we have a position to branch from and a position to branch to,
// insert the new conditional branch.
// Although SplitBlockPredecessors doesn't preserve loop-simplify in
// general, if we call it on all predecessors of all exits then it does.
- if (!ExitBlock->isLandingPad()) {
- SplitBlockPredecessors(ExitBlock, Preds, ".us-lcssa", this);
- } else {
- SmallVector<BasicBlock*, 2> NewBBs;
- SplitLandingPadPredecessors(ExitBlock, Preds, ".us-lcssa", ".us-lcssa",
- this, NewBBs);
- }
+ SplitBlockPredecessors(ExitBlock, Preds, ".us-lcssa",
+ /*AliasAnalysis*/ nullptr, DT, LI,
+ /*PreserveLCSSA*/ true);
}
}
// First step, split the preheader and exit blocks, and add these blocks to
// the LoopBlocks list.
- BasicBlock *NewPreheader = SplitEdge(loopPreheader, loopHeader, this);
+ BasicBlock *NewPreheader = SplitEdge(loopPreheader, loopHeader, DT, LI);
LoopBlocks.push_back(NewPreheader);
// We want the loop to come after the preheader, but before the exit blocks.
F->getBasicBlockList().splice(NewPreheader, F->getBasicBlockList(),
NewBlocks[0], F->end());
+ // FIXME: We could register any cloned assumptions instead of clearing the
+ // whole function's cache.
+ AC->clear();
+
// Now we create the new Loop object for the versioned loop.
Loop *NewLoop = CloneLoop(L, L->getParentLoop(), VMap, LI, LPM);
if (ParentLoop) {
// Make sure to add the cloned preheader and exit blocks to the parent loop
// as well.
- ParentLoop->addBasicBlockToLoop(NewBlocks[0], LI->getBase());
+ ParentLoop->addBasicBlockToLoop(NewBlocks[0], *LI);
}
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
BasicBlock *NewExit = cast<BasicBlock>(VMap[ExitBlocks[i]]);
// The new exit block should be in the same loop as the old one.
if (Loop *ExitBBLoop = LI->getLoopFor(ExitBlocks[i]))
- ExitBBLoop->addBasicBlockToLoop(NewExit, LI->getBase());
+ ExitBBLoop->addBasicBlockToLoop(NewExit, *LI);
assert(NewExit->getTerminator()->getNumSuccessors() == 1 &&
"Exit block should have been split to have one successor!");
++NumSimplify;
}
-/// RemoveLoopFromHierarchy - We have discovered that the specified loop has
-/// become unwrapped, either because the backedge was deleted, or because the
-/// edge into the header was removed. If the edge into the header from the
-/// latch block was removed, the loop is unwrapped but subloops are still alive,
-/// so they just reparent loops. If the loops are actually dead, they will be
-/// removed later.
-void LoopUnswitch::RemoveLoopFromHierarchy(Loop *L) {
- LPM->deleteLoopFromQueue(L);
- RemoveLoopFromWorklist(L);
-}
-
// RewriteLoopBodyWithConditionConstant - We know either that the value LIC has
// the value specified by Val in the specified loop, or we know it does NOT have
// that value. Rewrite any uses of LIC or of properties correlated to it.
// If we know that LIC is not Val, use this info to simplify code.
SwitchInst *SI = dyn_cast<SwitchInst>(UI);
- if (SI == 0 || !isa<ConstantInt>(Val)) continue;
+ if (!SI || !isa<ConstantInt>(Val)) continue;
SwitchInst::CaseIt DeadCase = SI->findCaseValue(cast<ConstantInt>(Val));
// Default case is live for multiple values.
// and hooked up so as to preserve the loop structure, because
// trying to update it is complicated. So instead we preserve the
// loop structure and put the block on a dead code path.
- SplitEdge(Switch, SISucc, this);
+ SplitEdge(Switch, SISucc, DT, LI);
// Compute the successors instead of relying on the return value
// of SplitEdge, since it may have split the switch successor
// after PHI nodes.
/// pass.
///
void LoopUnswitch::SimplifyCode(std::vector<Instruction*> &Worklist, Loop *L) {
+ const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
while (!Worklist.empty()) {
Instruction *I = Worklist.back();
Worklist.pop_back();
// See if instruction simplification can hack this up. This is common for
// things like "select false, X, Y" after unswitching made the condition be
// 'false'. TODO: update the domtree properly so we can pass it here.
- if (Value *V = SimplifyInstruction(I))
+ if (Value *V = SimplifyInstruction(I, DL))
if (LI->replacementPreservesLCSSAForm(I, V)) {
ReplaceUsesOfWith(I, V, Worklist, L, LPM);
continue;
projects / oota-llvm.git / blobdiff