//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "ifcvt"
#include "llvm/CodeGen/Passes.h"
#include "BranchFolding.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/LivePhysRegs.h"
+#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
using namespace llvm;
+#define DEBUG_TYPE "ifcvt"
+
// Hidden options for help debugging.
static cl::opt<int> IfCvtFnStart("ifcvt-fn-start", cl::init(-1), cl::Hidden);
static cl::opt<int> IfCvtFnStop("ifcvt-fn-stop", cl::init(-1), cl::Hidden);
IsAnalyzed(false), IsEnqueued(false), IsBrAnalyzable(false),
HasFallThrough(false), IsUnpredicable(false),
CannotBeCopied(false), ClobbersPred(false), NonPredSize(0),
- ExtraCost(0), ExtraCost2(0), BB(0), TrueBB(0), FalseBB(0) {}
+ ExtraCost(0), ExtraCost2(0), BB(nullptr), TrueBB(nullptr),
+ FalseBB(nullptr) {}
};
/// IfcvtToken - Record information about pending if-conversions to attempt:
const TargetLoweringBase *TLI;
const TargetInstrInfo *TII;
const TargetRegisterInfo *TRI;
+ const MachineBlockFrequencyInfo *MBFI;
const MachineBranchProbabilityInfo *MBPI;
MachineRegisterInfo *MRI;
initializeIfConverterPass(*PassRegistry::getPassRegistry());
}
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequired<MachineBlockFrequencyInfo>();
AU.addRequired<MachineBranchProbabilityInfo>();
MachineFunctionPass::getAnalysisUsage(AU);
}
- virtual bool runOnMachineFunction(MachineFunction &MF);
+ bool runOnMachineFunction(MachineFunction &MF) override;
private:
bool ReverseBranchCondition(BBInfo &BBI);
void PredicateBlock(BBInfo &BBI,
MachineBasicBlock::iterator E,
SmallVectorImpl<MachineOperand> &Cond,
- SmallSet<unsigned, 4> *LaterRedefs = 0);
+ SmallSet<unsigned, 4> *LaterRedefs = nullptr);
void CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI,
SmallVectorImpl<MachineOperand> &Cond,
bool IgnoreBr = false);
// blockAlwaysFallThrough - Block ends without a terminator.
bool blockAlwaysFallThrough(BBInfo &BBI) const {
- return BBI.IsBrAnalyzable && BBI.TrueBB == NULL;
+ return BBI.IsBrAnalyzable && BBI.TrueBB == nullptr;
}
// IfcvtTokenCmp - Used to sort if-conversion candidates.
INITIALIZE_PASS_END(IfConverter, "if-converter", "If Converter", false, false)
bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
- TLI = MF.getTarget().getTargetLowering();
- TII = MF.getTarget().getInstrInfo();
- TRI = MF.getTarget().getRegisterInfo();
+ TLI = MF.getSubtarget().getTargetLowering();
+ TII = MF.getSubtarget().getInstrInfo();
+ TRI = MF.getSubtarget().getRegisterInfo();
+ MBFI = &getAnalysis<MachineBlockFrequencyInfo>();
MBPI = &getAnalysis<MachineBranchProbabilityInfo>();
MRI = &MF.getRegInfo();
bool BFChange = false;
if (!PreRegAlloc) {
// Tail merge tend to expose more if-conversion opportunities.
- BranchFolder BF(true, false);
- BFChange = BF.OptimizeFunction(MF, TII,
- MF.getTarget().getRegisterInfo(),
+ BranchFolder BF(true, false, *MBFI, *MBPI);
+ BFChange = BF.OptimizeFunction(MF, TII, MF.getSubtarget().getRegisterInfo(),
getAnalysisIfAvailable<MachineModuleInfo>());
}
BBAnalysis.clear();
if (MadeChange && IfCvtBranchFold) {
- BranchFolder BF(false, false);
- BF.OptimizeFunction(MF, TII,
- MF.getTarget().getRegisterInfo(),
+ BranchFolder BF(false, false, *MBFI, *MBPI);
+ BF.OptimizeFunction(MF, TII, MF.getSubtarget().getRegisterInfo(),
getAnalysisIfAvailable<MachineModuleInfo>());
}
if (SuccBB != TrueBB)
return SuccBB;
}
- return NULL;
+ return nullptr;
}
/// ReverseBranchCondition - Reverse the condition of the end of the block
MachineFunction::iterator I = BB;
MachineFunction::iterator E = BB->getParent()->end();
if (++I == E)
- return NULL;
+ return nullptr;
return I;
}
FT = getNextBlock(FalseBBI.BB);
if (TT != FT)
return false;
- if (TT == NULL && (TrueBBI.IsBrAnalyzable || FalseBBI.IsBrAnalyzable))
+ if (!TT && (TrueBBI.IsBrAnalyzable || FalseBBI.IsBrAnalyzable))
return false;
if (TrueBBI.BB->pred_size() > 1 || FalseBBI.BB->pred_size() > 1)
return false;
bool AlreadyPredicated = !BBI.Predicate.empty();
// First analyze the end of BB branches.
- BBI.TrueBB = BBI.FalseBB = NULL;
+ BBI.TrueBB = BBI.FalseBB = nullptr;
BBI.BrCond.clear();
BBI.IsBrAnalyzable =
!TII->AnalyzeBranch(*BBI.BB, BBI.TrueBB, BBI.FalseBB, BBI.BrCond);
- BBI.HasFallThrough = BBI.IsBrAnalyzable && BBI.FalseBB == NULL;
+ BBI.HasFallThrough = BBI.IsBrAnalyzable && BBI.FalseBB == nullptr;
if (BBI.BrCond.size()) {
// No false branch. This BB must end with a conditional branch and a
/// next block).
static bool canFallThroughTo(MachineBasicBlock *BB, MachineBasicBlock *ToBB) {
MachineFunction::iterator PI = BB;
- MachineFunction::iterator I = llvm::next(PI);
+ MachineFunction::iterator I = std::next(PI);
MachineFunction::iterator TI = ToBB;
MachineFunction::iterator E = BB->getParent()->end();
while (I != TI) {
/// to determine if it can be if-converted. If predecessor is already enqueued,
/// dequeue it!
void IfConverter::InvalidatePreds(MachineBasicBlock *BB) {
- for (MachineBasicBlock::pred_iterator PI = BB->pred_begin(),
- E = BB->pred_end(); PI != E; ++PI) {
- BBInfo &PBBI = BBAnalysis[(*PI)->getNumber()];
+ for (const auto &Predecessor : BB->predecessors()) {
+ BBInfo &PBBI = BBAnalysis[Predecessor->getNumber()];
if (PBBI.IsDone || PBBI.BB == BB)
continue;
PBBI.IsAnalyzed = false;
const TargetInstrInfo *TII) {
DebugLoc dl; // FIXME: this is nowhere
SmallVector<MachineOperand, 0> NoCond;
- TII->InsertBranch(*BB, ToBB, NULL, NoCond, dl);
+ TII->InsertBranch(*BB, ToBB, nullptr, NoCond, dl);
}
/// RemoveExtraEdges - Remove true / false edges if either / both are no longer
/// successors.
void IfConverter::RemoveExtraEdges(BBInfo &BBI) {
- MachineBasicBlock *TBB = NULL, *FBB = NULL;
+ MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
SmallVector<MachineOperand, 4> Cond;
if (!TII->AnalyzeBranch(*BBI.BB, TBB, FBB, Cond))
BBI.BB->CorrectExtraCFGEdges(TBB, FBB, !Cond.empty());
return true;
}
+/// Scale down weights to fit into uint32_t. NewTrue is the new weight
+/// for successor TrueBB, and NewFalse is the new weight for successor
+/// FalseBB.
+static void ScaleWeights(uint64_t NewTrue, uint64_t NewFalse,
+ MachineBasicBlock *MBB,
+ const MachineBasicBlock *TrueBB,
+ const MachineBasicBlock *FalseBB,
+ const MachineBranchProbabilityInfo *MBPI) {
+ uint64_t NewMax = (NewTrue > NewFalse) ? NewTrue : NewFalse;
+ uint32_t Scale = (NewMax / UINT32_MAX) + 1;
+ for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
+ SE = MBB->succ_end();
+ SI != SE; ++SI) {
+ if (*SI == TrueBB)
+ MBB->setSuccWeight(SI, (uint32_t)(NewTrue / Scale));
+ else if (*SI == FalseBB)
+ MBB->setSuccWeight(SI, (uint32_t)(NewFalse / Scale));
+ else
+ MBB->setSuccWeight(SI, MBPI->getEdgeWeight(MBB, SI) / Scale);
+ }
+}
+
/// IfConvertTriangle - If convert a triangle sub-CFG.
///
bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
DontKill.clear();
- bool HasEarlyExit = CvtBBI->FalseBB != NULL;
+ bool HasEarlyExit = CvtBBI->FalseBB != nullptr;
+ uint64_t CvtNext = 0, CvtFalse = 0, BBNext = 0, BBCvt = 0, SumWeight = 0;
+ uint32_t WeightScale = 0;
+
+ if (HasEarlyExit) {
+ // Get weights before modifying CvtBBI->BB and BBI.BB.
+ CvtNext = MBPI->getEdgeWeight(CvtBBI->BB, NextBBI->BB);
+ CvtFalse = MBPI->getEdgeWeight(CvtBBI->BB, CvtBBI->FalseBB);
+ BBNext = MBPI->getEdgeWeight(BBI.BB, NextBBI->BB);
+ BBCvt = MBPI->getEdgeWeight(BBI.BB, CvtBBI->BB);
+ SumWeight = MBPI->getSumForBlock(CvtBBI->BB, WeightScale);
+ }
+
if (CvtBBI->BB->pred_size() > 1) {
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
// Copy instructions in the true block, predicate them, and add them to
CvtBBI->BrCond.end());
if (TII->ReverseBranchCondition(RevCond))
llvm_unreachable("Unable to reverse branch condition!");
- TII->InsertBranch(*BBI.BB, CvtBBI->FalseBB, NULL, RevCond, dl);
+ TII->InsertBranch(*BBI.BB, CvtBBI->FalseBB, nullptr, RevCond, dl);
BBI.BB->addSuccessor(CvtBBI->FalseBB);
+ // Update the edge weight for both CvtBBI->FalseBB and NextBBI.
+ // New_Weight(BBI.BB, NextBBI->BB) =
+ // Weight(BBI.BB, NextBBI->BB) * getSumForBlock(CvtBBI->BB) +
+ // Weight(BBI.BB, CvtBBI->BB) * Weight(CvtBBI->BB, NextBBI->BB)
+ // New_Weight(BBI.BB, CvtBBI->FalseBB) =
+ // Weight(BBI.BB, CvtBBI->BB) * Weight(CvtBBI->BB, CvtBBI->FalseBB)
+
+ uint64_t NewNext = BBNext * SumWeight + (BBCvt * CvtNext) / WeightScale;
+ uint64_t NewFalse = (BBCvt * CvtFalse) / WeightScale;
+ // We need to scale down all weights of BBI.BB to fit uint32_t.
+ // Here BBI.BB is connected to CvtBBI->FalseBB and will fall through to
+ // the next block.
+ ScaleWeights(NewNext, NewFalse, BBI.BB, getNextBlock(BBI.BB),
+ CvtBBI->FalseBB, MBPI);
}
// Merge in the 'false' block if the 'false' block has no other
PredicateBlock(*BBI2, DI2, *Cond2);
// Merge the true block into the entry of the diamond.
- MergeBlocks(BBI, *BBI1, TailBB == 0);
- MergeBlocks(BBI, *BBI2, TailBB == 0);
+ MergeBlocks(BBI, *BBI1, TailBB == nullptr);
+ MergeBlocks(BBI, *BBI2, TailBB == nullptr);
// If the if-converted block falls through or unconditionally branches into
// the tail block, and the tail block does not have other predecessors, then
SmallSet<unsigned, 4> &LaterRedefs,
const TargetInstrInfo *TII) {
bool SawStore = true;
- if (!MI->isSafeToMove(TII, 0, SawStore))
+ if (!MI->isSafeToMove(TII, nullptr, SawStore))
return false;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
SmallVectorImpl<MachineOperand> &Cond,
SmallSet<unsigned, 4> *LaterRedefs) {
bool AnyUnpred = false;
- bool MaySpec = LaterRedefs != 0;
+ bool MaySpec = LaterRedefs != nullptr;
for (MachineBasicBlock::iterator I = BBI.BB->begin(); I != E; ++I) {
if (I->isDebugValue() || TII->isPredicated(I))
continue;
#ifndef NDEBUG
dbgs() << "Unable to predicate " << *I << "!\n";
#endif
- llvm_unreachable(0);
+ llvm_unreachable(nullptr);
}
// If the predicated instruction now redefines a register as the result of
#ifndef NDEBUG
dbgs() << "Unable to predicate " << *I << "!\n";
#endif
- llvm_unreachable(0);
+ llvm_unreachable(nullptr);
}
}
std::vector<MachineBasicBlock *> Succs(FromBBI.BB->succ_begin(),
FromBBI.BB->succ_end());
MachineBasicBlock *NBB = getNextBlock(FromBBI.BB);
- MachineBasicBlock *FallThrough = FromBBI.HasFallThrough ? NBB : NULL;
+ MachineBasicBlock *FallThrough = FromBBI.HasFallThrough ? NBB : nullptr;
for (unsigned i = 0, e = Succs.size(); i != e; ++i) {
MachineBasicBlock *Succ = Succs[i];
std::vector<MachineBasicBlock *> Succs(FromBBI.BB->succ_begin(),
FromBBI.BB->succ_end());
MachineBasicBlock *NBB = getNextBlock(FromBBI.BB);
- MachineBasicBlock *FallThrough = FromBBI.HasFallThrough ? NBB : NULL;
+ MachineBasicBlock *FallThrough = FromBBI.HasFallThrough ? NBB : nullptr;
for (unsigned i = 0, e = Succs.size(); i != e; ++i) {
MachineBasicBlock *Succ = Succs[i];
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