//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the Evan Cheng and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "ifcvt"
+#include "BranchFolding.h"
#include "llvm/Function.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/STLExtras.h"
using namespace llvm;
-namespace {
- // Hidden options for help debugging.
- cl::opt<int> IfCvtFnStart("ifcvt-fn-start", cl::init(-1), cl::Hidden);
- cl::opt<int> IfCvtFnStop("ifcvt-fn-stop", cl::init(-1), cl::Hidden);
- cl::opt<int> IfCvtLimit("ifcvt-limit", cl::init(-1), cl::Hidden);
- cl::opt<bool> DisableSimple("disable-ifcvt-simple",
- cl::init(false), cl::Hidden);
- cl::opt<bool> DisableSimpleF("disable-ifcvt-simple-false",
- cl::init(false), cl::Hidden);
- cl::opt<bool> DisableTriangle("disable-ifcvt-triangle",
- cl::init(false), cl::Hidden);
- cl::opt<bool> DisableTriangleR("disable-ifcvt-triangle-rev",
- cl::init(false), cl::Hidden);
- cl::opt<bool> DisableTriangleF("disable-ifcvt-triangle-false",
- cl::init(false), cl::Hidden);
- cl::opt<bool> DisableTriangleFR("disable-ifcvt-triangle-false-rev",
- cl::init(false), cl::Hidden);
- cl::opt<bool> DisableDiamond("disable-ifcvt-diamond",
- cl::init(false), cl::Hidden);
-}
+// 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);
+static cl::opt<int> IfCvtLimit("ifcvt-limit", cl::init(-1), cl::Hidden);
+static cl::opt<bool> DisableSimple("disable-ifcvt-simple",
+ cl::init(false), cl::Hidden);
+static cl::opt<bool> DisableSimpleF("disable-ifcvt-simple-false",
+ cl::init(false), cl::Hidden);
+static cl::opt<bool> DisableTriangle("disable-ifcvt-triangle",
+ cl::init(false), cl::Hidden);
+static cl::opt<bool> DisableTriangleR("disable-ifcvt-triangle-rev",
+ cl::init(false), cl::Hidden);
+static cl::opt<bool> DisableTriangleF("disable-ifcvt-triangle-false",
+ cl::init(false), cl::Hidden);
+static cl::opt<bool> DisableTriangleFR("disable-ifcvt-triangle-false-rev",
+ cl::init(false), cl::Hidden);
+static cl::opt<bool> DisableDiamond("disable-ifcvt-diamond",
+ cl::init(false), cl::Hidden);
+static cl::opt<bool> IfCvtBranchFold("ifcvt-branch-fold",
+ cl::init(true), cl::Hidden);
STATISTIC(NumSimple, "Number of simple if-conversions performed");
STATISTIC(NumSimpleFalse, "Number of simple (F) if-conversions performed");
namespace {
class IfConverter : public MachineFunctionPass {
- enum BBICKind {
+ enum IfcvtKind {
ICNotClassfied, // BB data valid, but not classified.
- ICSimple, // BB is entry of an one split, no rejoin sub-CFG.
ICSimpleFalse, // Same as ICSimple, but on the false path.
- ICTriangle, // BB is entry of a triangle sub-CFG.
+ ICSimple, // BB is entry of an one split, no rejoin sub-CFG.
+ ICTriangleFRev, // Same as ICTriangleFalse, but false path rev condition.
ICTriangleRev, // Same as ICTriangle, but true path rev condition.
ICTriangleFalse, // Same as ICTriangle, but on the false path.
- ICTriangleFRev, // Same as ICTriangleFalse, but false path rev condition.
+ ICTriangle, // BB is entry of a triangle sub-CFG.
ICDiamond // BB is entry of a diamond sub-CFG.
};
/// diamond shape), its size, whether it's predicable, and whether any
/// instruction can clobber the 'would-be' predicate.
///
- /// Kind - Type of block. See BBICKind.
/// IsDone - True if BB is not to be considered for ifcvt.
/// IsBeingAnalyzed - True if BB is currently being analyzed.
/// IsAnalyzed - True if BB has been analyzed (info is still valid).
/// IsBrAnalyzable - True if AnalyzeBranch() returns false.
/// HasFallThrough - True if BB may fallthrough to the following BB.
/// IsUnpredicable - True if BB is known to be unpredicable.
- /// ClobbersPredicate- True if BB would modify the predicate (e.g. has
+ /// ClobbersPred - True if BB could modify predicates (e.g. has
/// cmp, call, etc.)
/// NonPredSize - Number of non-predicated instructions.
/// BB - Corresponding MachineBasicBlock.
/// BrCond - Conditions for end of block conditional branches.
/// Predicate - Predicate used in the BB.
struct BBInfo {
- BBICKind Kind;
bool IsDone : 1;
bool IsBeingAnalyzed : 1;
bool IsAnalyzed : 1;
bool IsBrAnalyzable : 1;
bool HasFallThrough : 1;
bool IsUnpredicable : 1;
+ bool CannotBeCopied : 1;
bool ClobbersPred : 1;
unsigned NonPredSize;
MachineBasicBlock *BB;
MachineBasicBlock *TrueBB;
MachineBasicBlock *FalseBB;
- MachineBasicBlock *TailBB;
- std::vector<MachineOperand> BrCond;
- std::vector<MachineOperand> Predicate;
- BBInfo() : Kind(ICNotClassfied), IsDone(false), IsBeingAnalyzed(false),
+ SmallVector<MachineOperand, 4> BrCond;
+ SmallVector<MachineOperand, 4> Predicate;
+ BBInfo() : IsDone(false), IsBeingAnalyzed(false),
IsAnalyzed(false), IsEnqueued(false), IsBrAnalyzable(false),
HasFallThrough(false), IsUnpredicable(false),
- ClobbersPred(false), NonPredSize(0),
- BB(0), TrueBB(0), FalseBB(0), TailBB(0) {}
+ CannotBeCopied(false), ClobbersPred(false), NonPredSize(0),
+ BB(0), TrueBB(0), FalseBB(0) {}
+ };
+
+ /// IfcvtToken - Record information about pending if-conversions to attempt:
+ /// BBI - Corresponding BBInfo.
+ /// Kind - Type of block. See IfcvtKind.
+ /// NeedSubsumption - True if the to-be-predicated BB has already been
+ /// predicated.
+ /// NumDups - Number of instructions that would be duplicated due
+ /// to this if-conversion. (For diamonds, the number of
+ /// identical instructions at the beginnings of both
+ /// paths).
+ /// NumDups2 - For diamonds, the number of identical instructions
+ /// at the ends of both paths.
+ struct IfcvtToken {
+ BBInfo &BBI;
+ IfcvtKind Kind;
+ bool NeedSubsumption;
+ unsigned NumDups;
+ unsigned NumDups2;
+ IfcvtToken(BBInfo &b, IfcvtKind k, bool s, unsigned d, unsigned d2 = 0)
+ : BBI(b), Kind(k), NeedSubsumption(s), NumDups(d), NumDups2(d2) {}
};
/// Roots - Basic blocks that do not have successors. These are the starting
const TargetLowering *TLI;
const TargetInstrInfo *TII;
+ const TargetRegisterInfo *TRI;
bool MadeChange;
+ int FnNum;
public:
static char ID;
- IfConverter() : MachineFunctionPass((intptr_t)&ID) {}
+ IfConverter() : MachineFunctionPass(ID), FnNum(-1) {}
virtual bool runOnMachineFunction(MachineFunction &MF);
- virtual const char *getPassName() const { return "If converter"; }
+ virtual const char *getPassName() const { return "If Converter"; }
private:
bool ReverseBranchCondition(BBInfo &BBI);
- bool ValidSimple(BBInfo &TrueBBI) const;
+ bool ValidSimple(BBInfo &TrueBBI, unsigned &Dups) const;
bool ValidTriangle(BBInfo &TrueBBI, BBInfo &FalseBBI,
- bool FalseBranch = false) const;
- bool ValidDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI) const;
+ bool FalseBranch, unsigned &Dups) const;
+ bool ValidDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI,
+ unsigned &Dups1, unsigned &Dups2) const;
void ScanInstructions(BBInfo &BBI);
- BBInfo &AnalyzeBlock(MachineBasicBlock *BB);
- bool FeasibilityAnalysis(BBInfo &BBI, std::vector<MachineOperand> &Cond,
+ BBInfo &AnalyzeBlock(MachineBasicBlock *BB,
+ std::vector<IfcvtToken*> &Tokens);
+ bool FeasibilityAnalysis(BBInfo &BBI, SmallVectorImpl<MachineOperand> &Cond,
bool isTriangle = false, bool RevBranch = false);
- bool AttemptRestructuring(BBInfo &BBI);
- bool AnalyzeBlocks(MachineFunction &MF,
- std::vector<BBInfo*> &Candidates);
- void ReTryPreds(MachineBasicBlock *BB);
+ void AnalyzeBlocks(MachineFunction &MF, std::vector<IfcvtToken*> &Tokens);
+ void InvalidatePreds(MachineBasicBlock *BB);
void RemoveExtraEdges(BBInfo &BBI);
- bool IfConvertSimple(BBInfo &BBI);
- bool IfConvertTriangle(BBInfo &BBI);
- bool IfConvertDiamond(BBInfo &BBI);
+ bool IfConvertSimple(BBInfo &BBI, IfcvtKind Kind);
+ bool IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind);
+ bool IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
+ unsigned NumDups1, unsigned NumDups2);
void PredicateBlock(BBInfo &BBI,
- std::vector<MachineOperand> &Cond,
- bool IgnoreTerm = false);
+ MachineBasicBlock::iterator E,
+ SmallVectorImpl<MachineOperand> &Cond,
+ SmallSet<unsigned, 4> &Redefs);
void CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI,
- std::vector<MachineOperand> &Cond,
+ SmallVectorImpl<MachineOperand> &Cond,
+ SmallSet<unsigned, 4> &Redefs,
bool IgnoreBr = false);
- void MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI);
+ void MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI, bool AddEdges = true);
+
+ bool MeetIfcvtSizeLimit(MachineBasicBlock &BB, unsigned Size) const {
+ return Size > 0 && TII->isProfitableToIfCvt(BB, Size);
+ }
+
+ bool MeetIfcvtSizeLimit(MachineBasicBlock &TBB, unsigned TSize,
+ MachineBasicBlock &FBB, unsigned FSize) const {
+ return TSize > 0 && FSize > 0 &&
+ TII->isProfitableToIfCvt(TBB, TSize, FBB, FSize);
+ }
// blockAlwaysFallThrough - Block ends without a terminator.
bool blockAlwaysFallThrough(BBInfo &BBI) const {
return BBI.IsBrAnalyzable && BBI.TrueBB == NULL;
}
- // IfcvtCandidateCmp - Used to sort if-conversion candidates.
- static bool IfcvtCandidateCmp(BBInfo* C1, BBInfo* C2){
- // Favor diamond over triangle, etc.
- return (unsigned)C1->Kind < (unsigned)C2->Kind;
+ // IfcvtTokenCmp - Used to sort if-conversion candidates.
+ static bool IfcvtTokenCmp(IfcvtToken *C1, IfcvtToken *C2) {
+ int Incr1 = (C1->Kind == ICDiamond)
+ ? -(int)(C1->NumDups + C1->NumDups2) : (int)C1->NumDups;
+ int Incr2 = (C2->Kind == ICDiamond)
+ ? -(int)(C2->NumDups + C2->NumDups2) : (int)C2->NumDups;
+ if (Incr1 > Incr2)
+ return true;
+ else if (Incr1 == Incr2) {
+ // Favors subsumption.
+ if (C1->NeedSubsumption == false && C2->NeedSubsumption == true)
+ return true;
+ else if (C1->NeedSubsumption == C2->NeedSubsumption) {
+ // Favors diamond over triangle, etc.
+ if ((unsigned)C1->Kind < (unsigned)C2->Kind)
+ return true;
+ else if (C1->Kind == C2->Kind)
+ return C1->BBI.BB->getNumber() < C2->BBI.BB->getNumber();
+ }
+ }
+ return false;
}
};
+
char IfConverter::ID = 0;
}
+INITIALIZE_PASS(IfConverter, "if-converter", "If Converter", false, false);
+
FunctionPass *llvm::createIfConverterPass() { return new IfConverter(); }
bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
TLI = MF.getTarget().getTargetLowering();
TII = MF.getTarget().getInstrInfo();
+ TRI = MF.getTarget().getRegisterInfo();
if (!TII) return false;
- static int FnNum = -1;
- DOUT << "\nIfcvt: function (" << ++FnNum << ") \'"
- << MF.getFunction()->getName() << "\'";
+ // Tail merge tend to expose more if-conversion opportunities.
+ BranchFolder BF(true);
+ bool BFChange = BF.OptimizeFunction(MF, TII,
+ MF.getTarget().getRegisterInfo(),
+ getAnalysisIfAvailable<MachineModuleInfo>());
+
+ DEBUG(dbgs() << "\nIfcvt: function (" << ++FnNum << ") \'"
+ << MF.getFunction()->getName() << "\'");
if (FnNum < IfCvtFnStart || (IfCvtFnStop != -1 && FnNum > IfCvtFnStop)) {
- DOUT << " skipped\n";
+ DEBUG(dbgs() << " skipped\n");
return false;
}
- DOUT << "\n";
+ DEBUG(dbgs() << "\n");
MF.RenumberBlocks();
BBAnalysis.resize(MF.getNumBlockIDs());
// Look for root nodes, i.e. blocks without successors.
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
- if (I->succ_size() == 0)
+ if (I->succ_empty())
Roots.push_back(I);
- std::vector<BBInfo*> Candidates;
+ std::vector<IfcvtToken*> Tokens;
MadeChange = false;
unsigned NumIfCvts = NumSimple + NumSimpleFalse + NumTriangle +
NumTriangleRev + NumTriangleFalse + NumTriangleFRev + NumDiamonds;
while (IfCvtLimit == -1 || (int)NumIfCvts < IfCvtLimit) {
- // Do an intial analysis for each basic block and finding all the potential
- // candidates to perform if-convesion.
- bool Change = AnalyzeBlocks(MF, Candidates);
- while (!Candidates.empty()) {
- BBInfo &BBI = *Candidates.back();
- Candidates.pop_back();
+ // Do an initial analysis for each basic block and find all the potential
+ // candidates to perform if-conversion.
+ bool Change = false;
+ AnalyzeBlocks(MF, Tokens);
+ while (!Tokens.empty()) {
+ IfcvtToken *Token = Tokens.back();
+ Tokens.pop_back();
+ BBInfo &BBI = Token->BBI;
+ IfcvtKind Kind = Token->Kind;
+ unsigned NumDups = Token->NumDups;
+ unsigned NumDups2 = Token->NumDups2;
+
+ delete Token;
// If the block has been evicted out of the queue or it has already been
// marked dead (due to it being predicated), then skip it.
- if (!BBI.IsEnqueued || BBI.IsDone)
+ if (BBI.IsDone)
+ BBI.IsEnqueued = false;
+ if (!BBI.IsEnqueued)
continue;
+
BBI.IsEnqueued = false;
bool RetVal = false;
- switch (BBI.Kind) {
+ switch (Kind) {
default: assert(false && "Unexpected!");
break;
case ICSimple:
case ICSimpleFalse: {
- bool isFalse = BBI.Kind == ICSimpleFalse;
+ bool isFalse = Kind == ICSimpleFalse;
if ((isFalse && DisableSimpleF) || (!isFalse && DisableSimple)) break;
- DOUT << "Ifcvt (Simple" << (BBI.Kind == ICSimpleFalse ? " false" : "")
- << "): BB#" << BBI.BB->getNumber() << " ("
- << ((BBI.Kind == ICSimpleFalse)
- ? BBI.FalseBB->getNumber() : BBI.TrueBB->getNumber()) << ") ";
- RetVal = IfConvertSimple(BBI);
- DOUT << (RetVal ? "succeeded!" : "failed!") << "\n";
- if (RetVal)
- if (isFalse) NumSimpleFalse++;
- else NumSimple++;
+ DEBUG(dbgs() << "Ifcvt (Simple" << (Kind == ICSimpleFalse ?
+ " false" : "")
+ << "): BB#" << BBI.BB->getNumber() << " ("
+ << ((Kind == ICSimpleFalse)
+ ? BBI.FalseBB->getNumber()
+ : BBI.TrueBB->getNumber()) << ") ");
+ RetVal = IfConvertSimple(BBI, Kind);
+ DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
+ if (RetVal) {
+ if (isFalse) ++NumSimpleFalse;
+ else ++NumSimple;
+ }
break;
}
case ICTriangle:
case ICTriangleRev:
case ICTriangleFalse:
case ICTriangleFRev: {
- bool isFalse = BBI.Kind == ICTriangleFalse;
- bool isRev = (BBI.Kind == ICTriangleRev || BBI.Kind == ICTriangleFRev);
+ bool isFalse = Kind == ICTriangleFalse;
+ bool isRev = (Kind == ICTriangleRev || Kind == ICTriangleFRev);
if (DisableTriangle && !isFalse && !isRev) break;
if (DisableTriangleR && !isFalse && isRev) break;
if (DisableTriangleF && isFalse && !isRev) break;
if (DisableTriangleFR && isFalse && isRev) break;
- DOUT << "Ifcvt (Triangle";
+ DEBUG(dbgs() << "Ifcvt (Triangle");
if (isFalse)
- DOUT << " false";
+ DEBUG(dbgs() << " false");
if (isRev)
- DOUT << " rev";
- DOUT << "): BB#" << BBI.BB->getNumber() << " (T:"
- << BBI.TrueBB->getNumber() << ",F:" << BBI.FalseBB->getNumber()
- << ") ";
- RetVal = IfConvertTriangle(BBI);
- DOUT << (RetVal ? "succeeded!" : "failed!") << "\n";
+ DEBUG(dbgs() << " rev");
+ DEBUG(dbgs() << "): BB#" << BBI.BB->getNumber() << " (T:"
+ << BBI.TrueBB->getNumber() << ",F:"
+ << BBI.FalseBB->getNumber() << ") ");
+ RetVal = IfConvertTriangle(BBI, Kind);
+ DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
if (RetVal) {
if (isFalse) {
- if (isRev) NumTriangleFRev++;
- else NumTriangleFalse++;
+ if (isRev) ++NumTriangleFRev;
+ else ++NumTriangleFalse;
} else {
- if (isRev) NumTriangleRev++;
- else NumTriangle++;
+ if (isRev) ++NumTriangleRev;
+ else ++NumTriangle;
}
}
break;
}
- case ICDiamond:
+ case ICDiamond: {
if (DisableDiamond) break;
- DOUT << "Ifcvt (Diamond): BB#" << BBI.BB->getNumber() << " (T:"
- << BBI.TrueBB->getNumber() << ",F:" << BBI.FalseBB->getNumber();
- if (BBI.TailBB)
- DOUT << "," << BBI.TailBB->getNumber() ;
- DOUT << ") ";
- RetVal = IfConvertDiamond(BBI);
- DOUT << (RetVal ? "succeeded!" : "failed!") << "\n";
- if (RetVal) NumDiamonds++;
+ DEBUG(dbgs() << "Ifcvt (Diamond): BB#" << BBI.BB->getNumber() << " (T:"
+ << BBI.TrueBB->getNumber() << ",F:"
+ << BBI.FalseBB->getNumber() << ") ");
+ RetVal = IfConvertDiamond(BBI, Kind, NumDups, NumDups2);
+ DEBUG(dbgs() << (RetVal ? "succeeded!" : "failed!") << "\n");
+ if (RetVal) ++NumDiamonds;
break;
}
+ }
+
Change |= RetVal;
NumIfCvts = NumSimple + NumSimpleFalse + NumTriangle + NumTriangleRev +
MadeChange |= Change;
}
+ // Delete tokens in case of early exit.
+ while (!Tokens.empty()) {
+ IfcvtToken *Token = Tokens.back();
+ Tokens.pop_back();
+ delete Token;
+ }
+
+ Tokens.clear();
Roots.clear();
BBAnalysis.clear();
+ if (MadeChange && IfCvtBranchFold) {
+ BranchFolder BF(false);
+ BF.OptimizeFunction(MF, TII,
+ MF.getTarget().getRegisterInfo(),
+ getAnalysisIfAvailable<MachineModuleInfo>());
+ }
+
+ MadeChange |= BFChange;
return MadeChange;
}
+/// findFalseBlock - BB has a fallthrough. Find its 'false' successor given
+/// its 'true' successor.
static MachineBasicBlock *findFalseBlock(MachineBasicBlock *BB,
MachineBasicBlock *TrueBB) {
for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
return NULL;
}
+/// ReverseBranchCondition - Reverse the condition of the end of the block
+/// branch. Swap block's 'true' and 'false' successors.
bool IfConverter::ReverseBranchCondition(BBInfo &BBI) {
+ DebugLoc dl; // FIXME: this is nowhere
if (!TII->ReverseBranchCondition(BBI.BrCond)) {
TII->RemoveBranch(*BBI.BB);
- TII->InsertBranch(*BBI.BB, BBI.FalseBB, BBI.TrueBB, BBI.BrCond);
+ TII->InsertBranch(*BBI.BB, BBI.FalseBB, BBI.TrueBB, BBI.BrCond, dl);
std::swap(BBI.TrueBB, BBI.FalseBB);
return true;
}
}
/// ValidSimple - Returns true if the 'true' block (along with its
-/// predecessor) forms a valid simple shape for ifcvt.
-bool IfConverter::ValidSimple(BBInfo &TrueBBI) const {
- if (TrueBBI.IsBeingAnalyzed)
+/// predecessor) forms a valid simple shape for ifcvt. It also returns the
+/// number of instructions that the ifcvt would need to duplicate if performed
+/// in Dups.
+bool IfConverter::ValidSimple(BBInfo &TrueBBI, unsigned &Dups) const {
+ Dups = 0;
+ if (TrueBBI.IsBeingAnalyzed || TrueBBI.IsDone)
+ return false;
+
+ if (TrueBBI.IsBrAnalyzable)
return false;
- if (TrueBBI.BB->pred_size() != 1) {
- if (TrueBBI.NonPredSize > TLI->getIfCvtDupBlockSizeLimit())
+ if (TrueBBI.BB->pred_size() > 1) {
+ if (TrueBBI.CannotBeCopied ||
+ !TII->isProfitableToDupForIfCvt(*TrueBBI.BB, TrueBBI.NonPredSize))
return false;
+ Dups = TrueBBI.NonPredSize;
}
- return !blockAlwaysFallThrough(TrueBBI) && TrueBBI.BrCond.size() == 0;
+ return true;
}
/// ValidTriangle - Returns true if the 'true' and 'false' blocks (along
/// with their common predecessor) forms a valid triangle shape for ifcvt.
+/// If 'FalseBranch' is true, it checks if 'true' block's false branch
+/// branches to the 'false' block rather than the other way around. It also
+/// returns the number of instructions that the ifcvt would need to duplicate
+/// if performed in 'Dups'.
bool IfConverter::ValidTriangle(BBInfo &TrueBBI, BBInfo &FalseBBI,
- bool FalseBranch) const {
- if (TrueBBI.IsBeingAnalyzed)
+ bool FalseBranch, unsigned &Dups) const {
+ Dups = 0;
+ if (TrueBBI.IsBeingAnalyzed || TrueBBI.IsDone)
return false;
- if (TrueBBI.BB->pred_size() != 1) {
+ if (TrueBBI.BB->pred_size() > 1) {
+ if (TrueBBI.CannotBeCopied)
+ return false;
+
unsigned Size = TrueBBI.NonPredSize;
- if (TrueBBI.FalseBB)
- ++Size;
- if (Size > TLI->getIfCvtDupBlockSizeLimit())
+ if (TrueBBI.IsBrAnalyzable) {
+ if (TrueBBI.TrueBB && TrueBBI.BrCond.empty())
+ // Ends with an unconditional branch. It will be removed.
+ --Size;
+ else {
+ MachineBasicBlock *FExit = FalseBranch
+ ? TrueBBI.TrueBB : TrueBBI.FalseBB;
+ if (FExit)
+ // Require a conditional branch
+ ++Size;
+ }
+ }
+ if (!TII->isProfitableToDupForIfCvt(*TrueBBI.BB, Size))
return false;
+ Dups = Size;
}
MachineBasicBlock *TExit = FalseBranch ? TrueBBI.FalseBB : TrueBBI.TrueBB;
return TExit && TExit == FalseBBI.BB;
}
+static
+MachineBasicBlock::iterator firstNonBranchInst(MachineBasicBlock *BB,
+ const TargetInstrInfo *TII) {
+ MachineBasicBlock::iterator I = BB->end();
+ while (I != BB->begin()) {
+ --I;
+ if (!I->getDesc().isBranch())
+ break;
+ }
+ return I;
+}
+
/// ValidDiamond - Returns true if the 'true' and 'false' blocks (along
/// with their common predecessor) forms a valid diamond shape for ifcvt.
-bool IfConverter::ValidDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI) const {
- if (TrueBBI.IsBeingAnalyzed || FalseBBI.IsBeingAnalyzed)
+bool IfConverter::ValidDiamond(BBInfo &TrueBBI, BBInfo &FalseBBI,
+ unsigned &Dups1, unsigned &Dups2) const {
+ Dups1 = Dups2 = 0;
+ if (TrueBBI.IsBeingAnalyzed || TrueBBI.IsDone ||
+ FalseBBI.IsBeingAnalyzed || FalseBBI.IsDone)
return false;
MachineBasicBlock *TT = TrueBBI.TrueBB;
return false;
if (TT == NULL && (TrueBBI.IsBrAnalyzable || FalseBBI.IsBrAnalyzable))
return false;
- // FIXME: Allow false block to have an early exit?
- return (TrueBBI.BB->pred_size() == 1 &&
- FalseBBI.BB->pred_size() == 1 &&
- !TrueBBI.FalseBB && !FalseBBI.FalseBB);
+ if (TrueBBI.BB->pred_size() > 1 || FalseBBI.BB->pred_size() > 1)
+ return false;
+
+ // FIXME: Allow true block to have an early exit?
+ if (TrueBBI.FalseBB || FalseBBI.FalseBB ||
+ (TrueBBI.ClobbersPred && FalseBBI.ClobbersPred))
+ return false;
+
+ MachineBasicBlock::iterator TI = TrueBBI.BB->begin();
+ MachineBasicBlock::iterator FI = FalseBBI.BB->begin();
+ MachineBasicBlock::iterator TIE = TrueBBI.BB->end();
+ MachineBasicBlock::iterator FIE = FalseBBI.BB->end();
+ // Skip dbg_value instructions
+ while (TI != TIE && TI->isDebugValue())
+ ++TI;
+ while (FI != FIE && FI->isDebugValue())
+ ++FI;
+ while (TI != TIE && FI != FIE) {
+ // Skip dbg_value instructions. These do not count.
+ if (TI->isDebugValue()) {
+ while (TI != TIE && TI->isDebugValue())
+ ++TI;
+ if (TI == TIE)
+ break;
+ }
+ if (FI->isDebugValue()) {
+ while (FI != FIE && FI->isDebugValue())
+ ++FI;
+ if (FI == FIE)
+ break;
+ }
+ if (!TI->isIdenticalTo(FI))
+ break;
+ ++Dups1;
+ ++TI;
+ ++FI;
+ }
+
+ TI = firstNonBranchInst(TrueBBI.BB, TII);
+ FI = firstNonBranchInst(FalseBBI.BB, TII);
+ MachineBasicBlock::iterator TIB = TrueBBI.BB->begin();
+ MachineBasicBlock::iterator FIB = FalseBBI.BB->begin();
+ // Skip dbg_value instructions at end of the bb's.
+ while (TI != TIB && TI->isDebugValue())
+ --TI;
+ while (FI != FIB && FI->isDebugValue())
+ --FI;
+ while (TI != TIB && FI != FIB) {
+ // Skip dbg_value instructions. These do not count.
+ if (TI->isDebugValue()) {
+ while (TI != TIB && TI->isDebugValue())
+ --TI;
+ if (TI == TIB)
+ break;
+ }
+ if (FI->isDebugValue()) {
+ while (FI != FIB && FI->isDebugValue())
+ --FI;
+ if (FI == FIB)
+ break;
+ }
+ if (!TI->isIdenticalTo(FI))
+ break;
+ ++Dups2;
+ --TI;
+ --FI;
+ }
+
+ return true;
}
/// ScanInstructions - Scan all the instructions in the block to determine if
/// the block is predicable. In most cases, that means all the instructions
-/// in the block has M_PREDICABLE flag. Also checks if the block contains any
+/// in the block are isPredicable(). Also checks if the block contains any
/// instruction which can clobber a predicate (e.g. condition code register).
/// If so, the block is not predicable unless it's the last instruction.
void IfConverter::ScanInstructions(BBInfo &BBI) {
if (BBI.IsDone)
return;
+ bool AlreadyPredicated = BBI.Predicate.size() > 0;
// First analyze the end of BB branches.
BBI.TrueBB = BBI.FalseBB = NULL;
BBI.BrCond.clear();
// No false branch. This BB must end with a conditional branch and a
// fallthrough.
if (!BBI.FalseBB)
- BBI.FalseBB = findFalseBlock(BBI.BB, BBI.TrueBB);
- assert(BBI.FalseBB && "Expected to find the fallthrough block!");
+ BBI.FalseBB = findFalseBlock(BBI.BB, BBI.TrueBB);
+ if (!BBI.FalseBB) {
+ // Malformed bcc? True and false blocks are the same?
+ BBI.IsUnpredicable = true;
+ return;
+ }
}
// Then scan all the instructions.
BBI.NonPredSize = 0;
BBI.ClobbersPred = false;
- bool SeenCondBr = false;
for (MachineBasicBlock::iterator I = BBI.BB->begin(), E = BBI.BB->end();
I != E; ++I) {
- const TargetInstrDescriptor *TID = I->getInstrDescriptor();
- bool isPredicated = TII->isPredicated(I);
- bool isCondBr = BBI.IsBrAnalyzable &&
- (TID->Flags & M_BRANCH_FLAG) != 0 && (TID->Flags & M_BARRIER_FLAG) == 0;
+ if (I->isDebugValue())
+ continue;
+
+ const TargetInstrDesc &TID = I->getDesc();
+ if (TID.isNotDuplicable())
+ BBI.CannotBeCopied = true;
- if (!isPredicated && !isCondBr)
- BBI.NonPredSize++;
+ bool isPredicated = TII->isPredicated(I);
+ bool isCondBr = BBI.IsBrAnalyzable && TID.isConditionalBranch();
+
+ if (!isCondBr) {
+ if (!isPredicated)
+ BBI.NonPredSize++;
+ else if (!AlreadyPredicated) {
+ // FIXME: This instruction is already predicated before the
+ // if-conversion pass. It's probably something like a conditional move.
+ // Mark this block unpredicable for now.
+ BBI.IsUnpredicable = true;
+ return;
+ }
+ }
if (BBI.ClobbersPred && !isPredicated) {
// Predicate modification instruction should end the block (except for
// already predicated instructions and end of block branches).
if (isCondBr) {
- SeenCondBr = true;
-
- // Conditional branches is not predicable. But it may be eliminated.
+ // A conditional branch is not predicable, but it may be eliminated.
continue;
}
// Predicate may have been modified, the subsequent (currently)
- // unpredocated instructions cannot be correctly predicated.
+ // unpredicated instructions cannot be correctly predicated.
BBI.IsUnpredicable = true;
return;
}
- if (TID->Flags & M_CLOBBERS_PRED)
+ // FIXME: Make use of PredDefs? e.g. ADDC, SUBC sets predicates but are
+ // still potentially predicable.
+ std::vector<MachineOperand> PredDefs;
+ if (TII->DefinesPredicate(I, PredDefs))
BBI.ClobbersPred = true;
- if ((TID->Flags & M_PREDICABLE) == 0) {
+ if (!TII->isPredicable(I)) {
BBI.IsUnpredicable = true;
return;
}
/// FeasibilityAnalysis - Determine if the block is a suitable candidate to be
/// predicated by the specified predicate.
bool IfConverter::FeasibilityAnalysis(BBInfo &BBI,
- std::vector<MachineOperand> &Pred,
+ SmallVectorImpl<MachineOperand> &Pred,
bool isTriangle, bool RevBranch) {
- // Forget about it if it's unpredicable.
- if (BBI.IsUnpredicable)
- return false;
-
- // If the block is dead, or it is going to be the entry block of a sub-CFG
- // that will be if-converted, then it cannot be predicated.
- if (BBI.IsDone || BBI.IsEnqueued)
- return false;
-
- // Check predication threshold.
- if (BBI.NonPredSize == 0 || BBI.NonPredSize > TLI->getIfCvtBlockSizeLimit())
+ // If the block is dead or unpredicable, then it cannot be predicated.
+ if (BBI.IsDone || BBI.IsUnpredicable)
return false;
// If it is already predicated, check if its predicate subsumes the new
if (!isTriangle)
return false;
- // Test predicate subsumsion.
- std::vector<MachineOperand> RevPred(Pred);
- std::vector<MachineOperand> Cond(BBI.BrCond);
+ // Test predicate subsumption.
+ SmallVector<MachineOperand, 4> RevPred(Pred.begin(), Pred.end());
+ SmallVector<MachineOperand, 4> Cond(BBI.BrCond.begin(), BBI.BrCond.end());
if (RevBranch) {
if (TII->ReverseBranchCondition(Cond))
return false;
/// AnalyzeBlock - Analyze the structure of the sub-CFG starting from
/// the specified block. Record its successors and whether it looks like an
/// if-conversion candidate.
-IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB) {
+IfConverter::BBInfo &IfConverter::AnalyzeBlock(MachineBasicBlock *BB,
+ std::vector<IfcvtToken*> &Tokens) {
BBInfo &BBI = BBAnalysis[BB->getNumber()];
if (BBI.IsAnalyzed || BBI.IsBeingAnalyzed)
BBI.BB = BB;
BBI.IsBeingAnalyzed = true;
- BBI.Kind = ICNotClassfied;
ScanInstructions(BBI);
- // Unanalyable or ends with fallthrough or unconditional branch.
- if (!BBI.IsBrAnalyzable || BBI.BrCond.size() == 0) {
+ // Unanalyzable or ends with fallthrough or unconditional branch.
+ if (!BBI.IsBrAnalyzable || BBI.BrCond.empty()) {
BBI.IsBeingAnalyzed = false;
BBI.IsAnalyzed = true;
return BBI;
return BBI;
}
- BBInfo &TrueBBI = AnalyzeBlock(BBI.TrueBB);
- BBInfo &FalseBBI = AnalyzeBlock(BBI.FalseBB);
+ // Do not ifcvt if true and false fallthrough blocks are the same.
+ if (!BBI.FalseBB) {
+ BBI.IsBeingAnalyzed = false;
+ BBI.IsAnalyzed = true;
+ return BBI;
+ }
+
+ BBInfo &TrueBBI = AnalyzeBlock(BBI.TrueBB, Tokens);
+ BBInfo &FalseBBI = AnalyzeBlock(BBI.FalseBB, Tokens);
if (TrueBBI.IsDone && FalseBBI.IsDone) {
BBI.IsBeingAnalyzed = false;
return BBI;
}
- std::vector<MachineOperand> RevCond(BBI.BrCond);
+ SmallVector<MachineOperand, 4> RevCond(BBI.BrCond.begin(), BBI.BrCond.end());
bool CanRevCond = !TII->ReverseBranchCondition(RevCond);
- if (CanRevCond && ValidDiamond(TrueBBI, FalseBBI) &&
- !(TrueBBI.ClobbersPred && FalseBBI.ClobbersPred) &&
+ unsigned Dups = 0;
+ unsigned Dups2 = 0;
+ bool TNeedSub = TrueBBI.Predicate.size() > 0;
+ bool FNeedSub = FalseBBI.Predicate.size() > 0;
+ bool Enqueued = false;
+ if (CanRevCond && ValidDiamond(TrueBBI, FalseBBI, Dups, Dups2) &&
+ MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize - (Dups + Dups2),
+ *FalseBBI.BB, FalseBBI.NonPredSize - (Dups + Dups2)) &&
FeasibilityAnalysis(TrueBBI, BBI.BrCond) &&
FeasibilityAnalysis(FalseBBI, RevCond)) {
// Diamond:
// \ /
// TailBB
// Note TailBB can be empty.
- BBI.Kind = ICDiamond;
- BBI.TailBB = TrueBBI.TrueBB;
- } else {
- // FIXME: Consider duplicating if BB is small.
- if (ValidTriangle(TrueBBI, FalseBBI) &&
- FeasibilityAnalysis(TrueBBI, BBI.BrCond, true)) {
- // Triangle:
- // EBB
- // | \_
- // | |
- // | TBB
- // | /
- // FBB
- BBI.Kind = ICTriangle;
- } else if (ValidTriangle(TrueBBI, FalseBBI, true) &&
- FeasibilityAnalysis(TrueBBI, BBI.BrCond, true, true)) {
- BBI.Kind = ICTriangleRev;
- } else if (ValidSimple(TrueBBI) &&
- FeasibilityAnalysis(TrueBBI, BBI.BrCond)) {
- // Simple (split, no rejoin):
- // EBB
- // | \_
- // | |
- // | TBB---> exit
- // |
- // FBB
- BBI.Kind = ICSimple;
- } else if (CanRevCond) {
- // Try the other path...
- if (ValidTriangle(FalseBBI, TrueBBI) &&
- FeasibilityAnalysis(FalseBBI, RevCond, true)) {
- BBI.Kind = ICTriangleFalse;
- } else if (ValidTriangle(FalseBBI, TrueBBI, true) &&
- FeasibilityAnalysis(FalseBBI, RevCond, true, true)) {
- BBI.Kind = ICTriangleFRev;
- } else if (ValidSimple(FalseBBI) &&
- FeasibilityAnalysis(FalseBBI, RevCond)) {
- BBI.Kind = ICSimpleFalse;
- }
+ Tokens.push_back(new IfcvtToken(BBI, ICDiamond, TNeedSub|FNeedSub, Dups,
+ Dups2));
+ Enqueued = true;
+ }
+
+ if (ValidTriangle(TrueBBI, FalseBBI, false, Dups) &&
+ MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize) &&
+ FeasibilityAnalysis(TrueBBI, BBI.BrCond, true)) {
+ // Triangle:
+ // EBB
+ // | \_
+ // | |
+ // | TBB
+ // | /
+ // FBB
+ Tokens.push_back(new IfcvtToken(BBI, ICTriangle, TNeedSub, Dups));
+ Enqueued = true;
+ }
+
+ if (ValidTriangle(TrueBBI, FalseBBI, true, Dups) &&
+ MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize) &&
+ FeasibilityAnalysis(TrueBBI, BBI.BrCond, true, true)) {
+ Tokens.push_back(new IfcvtToken(BBI, ICTriangleRev, TNeedSub, Dups));
+ Enqueued = true;
+ }
+
+ if (ValidSimple(TrueBBI, Dups) &&
+ MeetIfcvtSizeLimit(*TrueBBI.BB, TrueBBI.NonPredSize) &&
+ FeasibilityAnalysis(TrueBBI, BBI.BrCond)) {
+ // Simple (split, no rejoin):
+ // EBB
+ // | \_
+ // | |
+ // | TBB---> exit
+ // |
+ // FBB
+ Tokens.push_back(new IfcvtToken(BBI, ICSimple, TNeedSub, Dups));
+ Enqueued = true;
+ }
+
+ if (CanRevCond) {
+ // Try the other path...
+ if (ValidTriangle(FalseBBI, TrueBBI, false, Dups) &&
+ MeetIfcvtSizeLimit(*FalseBBI.BB, FalseBBI.NonPredSize) &&
+ FeasibilityAnalysis(FalseBBI, RevCond, true)) {
+ Tokens.push_back(new IfcvtToken(BBI, ICTriangleFalse, FNeedSub, Dups));
+ Enqueued = true;
+ }
+
+ if (ValidTriangle(FalseBBI, TrueBBI, true, Dups) &&
+ MeetIfcvtSizeLimit(*FalseBBI.BB, FalseBBI.NonPredSize) &&
+ FeasibilityAnalysis(FalseBBI, RevCond, true, true)) {
+ Tokens.push_back(new IfcvtToken(BBI, ICTriangleFRev, FNeedSub, Dups));
+ Enqueued = true;
+ }
+
+ if (ValidSimple(FalseBBI, Dups) &&
+ MeetIfcvtSizeLimit(*FalseBBI.BB, FalseBBI.NonPredSize) &&
+ FeasibilityAnalysis(FalseBBI, RevCond)) {
+ Tokens.push_back(new IfcvtToken(BBI, ICSimpleFalse, FNeedSub, Dups));
+ Enqueued = true;
}
}
+ BBI.IsEnqueued = Enqueued;
BBI.IsBeingAnalyzed = false;
BBI.IsAnalyzed = true;
return BBI;
}
-/// AttemptRestructuring - Restructure the sub-CFG rooted in the given block to
-/// expose more if-conversion opportunities. e.g.
-///
-/// cmp
-/// b le BB1
-/// / \____
-/// / |
-/// cmp |
-/// b eq BB1 |
-/// / \____ |
-/// / \ |
-/// BB1
-/// ==>
-///
-/// cmp
-/// b eq BB1
-/// / \____
-/// / |
-/// cmp |
-/// b le BB1 |
-/// / \____ |
-/// / \ |
-/// BB1
-bool IfConverter::AttemptRestructuring(BBInfo &BBI) {
- return false;
-}
-
/// AnalyzeBlocks - Analyze all blocks and find entries for all if-conversion
-/// candidates. It returns true if any CFG restructuring is done to expose more
-/// if-conversion opportunities.
-bool IfConverter::AnalyzeBlocks(MachineFunction &MF,
- std::vector<BBInfo*> &Candidates) {
- bool Change = false;
+/// candidates.
+void IfConverter::AnalyzeBlocks(MachineFunction &MF,
+ std::vector<IfcvtToken*> &Tokens) {
std::set<MachineBasicBlock*> Visited;
for (unsigned i = 0, e = Roots.size(); i != e; ++i) {
for (idf_ext_iterator<MachineBasicBlock*> I=idf_ext_begin(Roots[i],Visited),
E = idf_ext_end(Roots[i], Visited); I != E; ++I) {
MachineBasicBlock *BB = *I;
- BBInfo &BBI = AnalyzeBlock(BB);
- switch (BBI.Kind) {
- case ICSimple:
- case ICSimpleFalse:
- case ICTriangle:
- case ICTriangleRev:
- case ICTriangleFalse:
- case ICTriangleFRev:
- case ICDiamond:
- BBI.IsEnqueued = true;
- Candidates.push_back(&BBI);
- break;
- default:
- Change |= AttemptRestructuring(BBI);
- break;
- }
+ AnalyzeBlock(BB, Tokens);
}
}
// Sort to favor more complex ifcvt scheme.
- std::stable_sort(Candidates.begin(), Candidates.end(), IfcvtCandidateCmp);
-
- return Change;
+ std::stable_sort(Tokens.begin(), Tokens.end(), IfcvtTokenCmp);
}
/// canFallThroughTo - Returns true either if ToBB is the next block after BB or
/// that all the intervening blocks are empty (given BB can fall through to its
/// next block).
static bool canFallThroughTo(MachineBasicBlock *BB, MachineBasicBlock *ToBB) {
- MachineFunction::iterator I = BB;
+ MachineFunction::iterator PI = BB;
+ MachineFunction::iterator I = llvm::next(PI);
MachineFunction::iterator TI = ToBB;
MachineFunction::iterator E = BB->getParent()->end();
- while (++I != TI)
- if (I == E || !I->empty())
+ while (I != TI) {
+ // Check isSuccessor to avoid case where the next block is empty, but
+ // it's not a successor.
+ if (I == E || !I->empty() || !PI->isSuccessor(I))
return false;
+ PI = I++;
+ }
return true;
}
-/// ReTryPreds - Invalidate predecessor BB info so it would be re-analyzed
-/// to determine if it can be if-converted. If predecessor is already
-/// enqueud, dequeue it!
-void IfConverter::ReTryPreds(MachineBasicBlock *BB) {
+/// InvalidatePreds - Invalidate predecessor BB info so it would be re-analyzed
+/// 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()];
if (PBBI.IsDone || PBBI.BB == BB)
continue;
- PBBI.Kind = ICNotClassfied;
PBBI.IsAnalyzed = false;
PBBI.IsEnqueued = false;
}
///
static void InsertUncondBranch(MachineBasicBlock *BB, MachineBasicBlock *ToBB,
const TargetInstrInfo *TII) {
- std::vector<MachineOperand> NoCond;
- TII->InsertBranch(*BB, ToBB, NULL, NoCond);
+ DebugLoc dl; // FIXME: this is nowhere
+ SmallVector<MachineOperand, 0> NoCond;
+ TII->InsertBranch(*BB, ToBB, NULL, NoCond, dl);
}
/// RemoveExtraEdges - Remove true / false edges if either / both are no longer
/// successors.
void IfConverter::RemoveExtraEdges(BBInfo &BBI) {
MachineBasicBlock *TBB = NULL, *FBB = NULL;
- std::vector<MachineOperand> Cond;
- bool isAnalyzable = !TII->AnalyzeBranch(*BBI.BB, TBB, FBB, Cond);
- bool CanFallthrough = isAnalyzable && (TBB == NULL || FBB == NULL);
- if (BBI.TrueBB && BBI.BB->isSuccessor(BBI.TrueBB))
- if (!(BBI.TrueBB == TBB || BBI.TrueBB == FBB ||
- (CanFallthrough && getNextBlock(BBI.BB) == BBI.TrueBB)))
- BBI.BB->removeSuccessor(BBI.TrueBB);
- if (BBI.FalseBB && BBI.BB->isSuccessor(BBI.FalseBB))
- if (!(BBI.FalseBB == TBB || BBI.FalseBB == FBB ||
- (CanFallthrough && getNextBlock(BBI.BB) == BBI.FalseBB)))
- BBI.BB->removeSuccessor(BBI.FalseBB);
+ SmallVector<MachineOperand, 4> Cond;
+ if (!TII->AnalyzeBranch(*BBI.BB, TBB, FBB, Cond))
+ BBI.BB->CorrectExtraCFGEdges(TBB, FBB, !Cond.empty());
+}
+
+/// InitPredRedefs / UpdatePredRedefs - Defs by predicated instructions are
+/// modeled as read + write (sort like two-address instructions). These
+/// routines track register liveness and add implicit uses to if-converted
+/// instructions to conform to the model.
+static void InitPredRedefs(MachineBasicBlock *BB, SmallSet<unsigned,4> &Redefs,
+ const TargetRegisterInfo *TRI) {
+ for (MachineBasicBlock::livein_iterator I = BB->livein_begin(),
+ E = BB->livein_end(); I != E; ++I) {
+ unsigned Reg = *I;
+ Redefs.insert(Reg);
+ for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
+ *Subreg; ++Subreg)
+ Redefs.insert(*Subreg);
+ }
+}
+
+static void UpdatePredRedefs(MachineInstr *MI, SmallSet<unsigned,4> &Redefs,
+ const TargetRegisterInfo *TRI,
+ bool AddImpUse = false) {
+ SmallVector<unsigned, 4> Defs;
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isReg())
+ continue;
+ unsigned Reg = MO.getReg();
+ if (!Reg)
+ continue;
+ if (MO.isDef())
+ Defs.push_back(Reg);
+ else if (MO.isKill()) {
+ Redefs.erase(Reg);
+ for (const unsigned *SR = TRI->getSubRegisters(Reg); *SR; ++SR)
+ Redefs.erase(*SR);
+ }
+ }
+ for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
+ unsigned Reg = Defs[i];
+ if (Redefs.count(Reg)) {
+ if (AddImpUse)
+ // Treat predicated update as read + write.
+ MI->addOperand(MachineOperand::CreateReg(Reg, false/*IsDef*/,
+ true/*IsImp*/,false/*IsKill*/));
+ } else {
+ Redefs.insert(Reg);
+ for (const unsigned *SR = TRI->getSubRegisters(Reg); *SR; ++SR)
+ Redefs.insert(*SR);
+ }
+ }
+}
+
+static void UpdatePredRedefs(MachineBasicBlock::iterator I,
+ MachineBasicBlock::iterator E,
+ SmallSet<unsigned,4> &Redefs,
+ const TargetRegisterInfo *TRI) {
+ while (I != E) {
+ UpdatePredRedefs(I, Redefs, TRI);
+ ++I;
+ }
}
/// IfConvertSimple - If convert a simple (split, no rejoin) sub-CFG.
///
-bool IfConverter::IfConvertSimple(BBInfo &BBI) {
+bool IfConverter::IfConvertSimple(BBInfo &BBI, IfcvtKind Kind) {
BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
BBInfo *CvtBBI = &TrueBBI;
BBInfo *NextBBI = &FalseBBI;
- std::vector<MachineOperand> Cond(BBI.BrCond);
- if (BBI.Kind == ICSimpleFalse) {
+ SmallVector<MachineOperand, 4> Cond(BBI.BrCond.begin(), BBI.BrCond.end());
+ if (Kind == ICSimpleFalse)
std::swap(CvtBBI, NextBBI);
- TII->ReverseBranchCondition(Cond);
+
+ if (CvtBBI->IsDone ||
+ (CvtBBI->CannotBeCopied && CvtBBI->BB->pred_size() > 1)) {
+ // Something has changed. It's no longer safe to predicate this block.
+ BBI.IsAnalyzed = false;
+ CvtBBI->IsAnalyzed = false;
+ return false;
}
+ if (Kind == ICSimpleFalse)
+ if (TII->ReverseBranchCondition(Cond))
+ assert(false && "Unable to reverse branch condition!");
+
+ // Initialize liveins to the first BB. These are potentiall redefined by
+ // predicated instructions.
+ SmallSet<unsigned, 4> Redefs;
+ InitPredRedefs(CvtBBI->BB, Redefs, TRI);
+ InitPredRedefs(NextBBI->BB, Redefs, TRI);
+
if (CvtBBI->BB->pred_size() > 1) {
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
- // Copy instructions in the true block, predicate them add them to
+ // Copy instructions in the true block, predicate them, and add them to
// the entry block.
- CopyAndPredicateBlock(BBI, *CvtBBI, Cond);
+ CopyAndPredicateBlock(BBI, *CvtBBI, Cond, Redefs);
} else {
- PredicateBlock(*CvtBBI, Cond);
+ PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond, Redefs);
// Merge converted block into entry block.
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
// Update block info. BB can be iteratively if-converted.
if (!IterIfcvt)
BBI.IsDone = true;
- ReTryPreds(BBI.BB);
+ InvalidatePreds(BBI.BB);
CvtBBI->IsDone = true;
// FIXME: Must maintain LiveIns.
/// IfConvertTriangle - If convert a triangle sub-CFG.
///
-bool IfConverter::IfConvertTriangle(BBInfo &BBI) {
+bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
BBInfo *CvtBBI = &TrueBBI;
BBInfo *NextBBI = &FalseBBI;
+ DebugLoc dl; // FIXME: this is nowhere
- std::vector<MachineOperand> Cond(BBI.BrCond);
- if (BBI.Kind == ICTriangleFalse || BBI.Kind == ICTriangleFRev) {
+ SmallVector<MachineOperand, 4> Cond(BBI.BrCond.begin(), BBI.BrCond.end());
+ if (Kind == ICTriangleFalse || Kind == ICTriangleFRev)
std::swap(CvtBBI, NextBBI);
- TII->ReverseBranchCondition(Cond);
+
+ if (CvtBBI->IsDone ||
+ (CvtBBI->CannotBeCopied && CvtBBI->BB->pred_size() > 1)) {
+ // Something has changed. It's no longer safe to predicate this block.
+ BBI.IsAnalyzed = false;
+ CvtBBI->IsAnalyzed = false;
+ return false;
}
- if (BBI.Kind == ICTriangleRev || BBI.Kind == ICTriangleFRev) {
- ReverseBranchCondition(*CvtBBI);
- // BB has been changed, modify its predecessors (except for this
- // one) so they don't get ifcvt'ed based on bad intel.
- for (MachineBasicBlock::pred_iterator PI = CvtBBI->BB->pred_begin(),
- E = CvtBBI->BB->pred_end(); PI != E; ++PI) {
- MachineBasicBlock *PBB = *PI;
- if (PBB == BBI.BB)
- continue;
- BBInfo &PBBI = BBAnalysis[PBB->getNumber()];
- if (PBBI.IsEnqueued) {
- PBBI.Kind = ICNotClassfied;
- PBBI.IsAnalyzed = false;
- PBBI.IsEnqueued = false;
+
+ if (Kind == ICTriangleFalse || Kind == ICTriangleFRev)
+ if (TII->ReverseBranchCondition(Cond))
+ assert(false && "Unable to reverse branch condition!");
+
+ if (Kind == ICTriangleRev || Kind == ICTriangleFRev) {
+ if (ReverseBranchCondition(*CvtBBI)) {
+ // BB has been changed, modify its predecessors (except for this
+ // one) so they don't get ifcvt'ed based on bad intel.
+ for (MachineBasicBlock::pred_iterator PI = CvtBBI->BB->pred_begin(),
+ E = CvtBBI->BB->pred_end(); PI != E; ++PI) {
+ MachineBasicBlock *PBB = *PI;
+ if (PBB == BBI.BB)
+ continue;
+ BBInfo &PBBI = BBAnalysis[PBB->getNumber()];
+ if (PBBI.IsEnqueued) {
+ PBBI.IsAnalyzed = false;
+ PBBI.IsEnqueued = false;
+ }
}
}
}
+ // Initialize liveins to the first BB. These are potentially redefined by
+ // predicated instructions.
+ SmallSet<unsigned, 4> Redefs;
+ InitPredRedefs(CvtBBI->BB, Redefs, TRI);
+ InitPredRedefs(NextBBI->BB, Redefs, TRI);
+
bool HasEarlyExit = CvtBBI->FalseBB != NULL;
- bool DupBB = CvtBBI->BB->pred_size() > 1;
- if (DupBB) {
+ if (CvtBBI->BB->pred_size() > 1) {
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
- // Copy instructions in the true block, predicate them add them to
+ // Copy instructions in the true block, predicate them, and add them to
// the entry block.
- CopyAndPredicateBlock(BBI, *CvtBBI, Cond, true);
+ CopyAndPredicateBlock(BBI, *CvtBBI, Cond, Redefs, true);
} else {
// Predicate the 'true' block after removing its branch.
CvtBBI->NonPredSize -= TII->RemoveBranch(*CvtBBI->BB);
- PredicateBlock(*CvtBBI, Cond);
+ PredicateBlock(*CvtBBI, CvtBBI->BB->end(), Cond, Redefs);
+
+ // Now merge the entry of the triangle with the true block.
+ BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
+ MergeBlocks(BBI, *CvtBBI, false);
}
// If 'true' block has a 'false' successor, add an exit branch to it.
if (HasEarlyExit) {
- std::vector<MachineOperand> RevCond(CvtBBI->BrCond);
+ SmallVector<MachineOperand, 4> RevCond(CvtBBI->BrCond.begin(),
+ CvtBBI->BrCond.end());
if (TII->ReverseBranchCondition(RevCond))
assert(false && "Unable to reverse branch condition!");
- if (DupBB) {
- TII->InsertBranch(*BBI.BB, CvtBBI->FalseBB, NULL, RevCond);
- BBI.BB->addSuccessor(CvtBBI->FalseBB);
- } else {
- TII->InsertBranch(*CvtBBI->BB, CvtBBI->FalseBB, NULL, RevCond);
- }
- }
-
- if (!DupBB) {
- // Now merge the entry of the triangle with the true block.
- BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
- MergeBlocks(BBI, *CvtBBI);
+ TII->InsertBranch(*BBI.BB, CvtBBI->FalseBB, NULL, RevCond, dl);
+ BBI.BB->addSuccessor(CvtBBI->FalseBB);
}
// Merge in the 'false' block if the 'false' block has no other
- // predecessors. Otherwise, add a unconditional branch from to 'false'.
+ // predecessors. Otherwise, add an unconditional branch to 'false'.
bool FalseBBDead = false;
bool IterIfcvt = true;
bool isFallThrough = canFallThroughTo(BBI.BB, NextBBI->BB);
// Only merge them if the true block does not fallthrough to the false
// block. By not merging them, we make it possible to iteratively
// ifcvt the blocks.
- if (!HasEarlyExit && NextBBI->BB->pred_size() == 1) {
+ if (!HasEarlyExit &&
+ NextBBI->BB->pred_size() == 1 && !NextBBI->HasFallThrough) {
MergeBlocks(BBI, *NextBBI);
FalseBBDead = true;
} else {
RemoveExtraEdges(BBI);
// Update block info. BB can be iteratively if-converted.
- if (!IterIfcvt)
+ if (!IterIfcvt)
BBI.IsDone = true;
- ReTryPreds(BBI.BB);
+ InvalidatePreds(BBI.BB);
CvtBBI->IsDone = true;
if (FalseBBDead)
NextBBI->IsDone = true;
/// IfConvertDiamond - If convert a diamond sub-CFG.
///
-bool IfConverter::IfConvertDiamond(BBInfo &BBI) {
+bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
+ unsigned NumDups1, unsigned NumDups2) {
BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
-
- SmallVector<MachineInstr*, 2> Dups;
- if (!BBI.TailBB) {
- // No common merge block. Check if the terminators (e.g. return) are
- // the same or predicable.
- MachineBasicBlock::iterator TT = BBI.TrueBB->getFirstTerminator();
- MachineBasicBlock::iterator FT = BBI.FalseBB->getFirstTerminator();
- while (TT != BBI.TrueBB->end() && FT != BBI.FalseBB->end()) {
- if (TT->isIdenticalTo(FT))
- Dups.push_back(TT); // Will erase these later.
- else if ((TT->getInstrDescriptor()->Flags & M_PREDICABLE) == 0 ||
- (FT->getInstrDescriptor()->Flags & M_PREDICABLE) == 0)
- return false; // Can't if-convert. Abort!
- ++TT;
- ++FT;
- }
-
- // One of the two pathes have more terminators, make sure they are
- // all predicable.
- while (TT != BBI.TrueBB->end()) {
- if ((TT->getInstrDescriptor()->Flags & M_PREDICABLE) == 0)
- return false; // Can't if-convert. Abort!
- ++TT;
- }
- while (FT != BBI.FalseBB->end()) {
- if ((FT->getInstrDescriptor()->Flags & M_PREDICABLE) == 0)
- return false; // Can't if-convert. Abort!
- ++FT;
- }
+ MachineBasicBlock *TailBB = TrueBBI.TrueBB;
+ // True block must fall through or end with an unanalyzable terminator.
+ if (!TailBB) {
+ if (blockAlwaysFallThrough(TrueBBI))
+ TailBB = FalseBBI.TrueBB;
+ assert((TailBB || !TrueBBI.IsBrAnalyzable) && "Unexpected!");
}
- // Remove the duplicated instructions from the 'true' block.
- for (unsigned i = 0, e = Dups.size(); i != e; ++i) {
- Dups[i]->eraseFromParent();
- --TrueBBI.NonPredSize;
+ if (TrueBBI.IsDone || FalseBBI.IsDone ||
+ TrueBBI.BB->pred_size() > 1 ||
+ FalseBBI.BB->pred_size() > 1) {
+ // Something has changed. It's no longer safe to predicate these blocks.
+ BBI.IsAnalyzed = false;
+ TrueBBI.IsAnalyzed = false;
+ FalseBBI.IsAnalyzed = false;
+ return false;
}
-
- // Merge the 'true' and 'false' blocks by copying the instructions
- // from the 'false' block to the 'true' block. That is, unless the true
- // block would clobber the predicate, in that case, do the opposite.
+
+ // Put the predicated instructions from the 'true' block before the
+ // instructions from the 'false' block, unless the true block would clobber
+ // the predicate, in which case, do the opposite.
BBInfo *BBI1 = &TrueBBI;
BBInfo *BBI2 = &FalseBBI;
- std::vector<MachineOperand> RevCond(BBI.BrCond);
- TII->ReverseBranchCondition(RevCond);
- std::vector<MachineOperand> *Cond1 = &BBI.BrCond;
- std::vector<MachineOperand> *Cond2 = &RevCond;
- // Check the 'true' and 'false' blocks if either isn't ended with a branch.
- // Either the block fallthrough to another block or it ends with a
- // return. If it's the former, add a branch to its successor.
- bool NeedBr1 = !BBI1->TrueBB && BBI1->BB->succ_size();
- bool NeedBr2 = !BBI2->TrueBB && BBI2->BB->succ_size();
-
- if ((TrueBBI.ClobbersPred && !FalseBBI.ClobbersPred) ||
- (!TrueBBI.ClobbersPred && !FalseBBI.ClobbersPred &&
- NeedBr1 && !NeedBr2)) {
+ SmallVector<MachineOperand, 4> RevCond(BBI.BrCond.begin(), BBI.BrCond.end());
+ if (TII->ReverseBranchCondition(RevCond))
+ assert(false && "Unable to reverse branch condition!");
+ SmallVector<MachineOperand, 4> *Cond1 = &BBI.BrCond;
+ SmallVector<MachineOperand, 4> *Cond2 = &RevCond;
+
+ // Figure out the more profitable ordering.
+ bool DoSwap = false;
+ if (TrueBBI.ClobbersPred && !FalseBBI.ClobbersPred)
+ DoSwap = true;
+ else if (TrueBBI.ClobbersPred == FalseBBI.ClobbersPred) {
+ if (TrueBBI.NonPredSize > FalseBBI.NonPredSize)
+ DoSwap = true;
+ }
+ if (DoSwap) {
std::swap(BBI1, BBI2);
std::swap(Cond1, Cond2);
- std::swap(NeedBr1, NeedBr2);
- }
-
- // Predicate the 'true' block after removing its branch.
- BBI1->NonPredSize -= TII->RemoveBranch(*BBI1->BB);
- PredicateBlock(*BBI1, *Cond1);
-
- // Add an early exit branch if needed.
- if (NeedBr1)
- TII->InsertBranch(*BBI1->BB, *BBI1->BB->succ_begin(), NULL, *Cond1);
-
- // Predicate the 'false' block.
- PredicateBlock(*BBI2, *Cond2, true);
-
- // Add an unconditional branch from 'false' to to 'false' successor if it
- // will not be the fallthrough block.
- if (NeedBr2 && !NeedBr1) {
- // If BBI2 isn't going to be merged in, then the existing fallthrough
- // or branch is fine.
- if (!canFallThroughTo(BBI.BB, *BBI2->BB->succ_begin())) {
- InsertUncondBranch(BBI2->BB, *BBI2->BB->succ_begin(), TII);
- BBI2->HasFallThrough = false;
- }
}
- // Keep them as two separate blocks if there is an early exit.
- if (!NeedBr1)
- MergeBlocks(*BBI1, *BBI2);
-
// Remove the conditional branch from entry to the blocks.
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
- // Merge the combined block into the entry of the diamond.
- MergeBlocks(BBI, *BBI1);
+ // Initialize liveins to the first BB. These are potentially redefined by
+ // predicated instructions.
+ SmallSet<unsigned, 4> Redefs;
+ InitPredRedefs(BBI1->BB, Redefs, TRI);
+
+ // Remove the duplicated instructions at the beginnings of both paths.
+ MachineBasicBlock::iterator DI1 = BBI1->BB->begin();
+ MachineBasicBlock::iterator DI2 = BBI2->BB->begin();
+ MachineBasicBlock::iterator DIE1 = BBI1->BB->end();
+ MachineBasicBlock::iterator DIE2 = BBI2->BB->end();
+ // Skip dbg_value instructions
+ while (DI1 != DIE1 && DI1->isDebugValue())
+ ++DI1;
+ while (DI2 != DIE2 && DI2->isDebugValue())
+ ++DI2;
+ BBI1->NonPredSize -= NumDups1;
+ BBI2->NonPredSize -= NumDups1;
+
+ // Skip past the dups on each side separately since there may be
+ // differing dbg_value entries.
+ for (unsigned i = 0; i < NumDups1; ++DI1) {
+ if (!DI1->isDebugValue())
+ ++i;
+ }
+ while (NumDups1 != 0) {
+ ++DI2;
+ if (!DI2->isDebugValue())
+ --NumDups1;
+ }
+
+ UpdatePredRedefs(BBI1->BB->begin(), DI1, Redefs, TRI);
+ BBI.BB->splice(BBI.BB->end(), BBI1->BB, BBI1->BB->begin(), DI1);
+ BBI2->BB->erase(BBI2->BB->begin(), DI2);
- // 'True' and 'false' aren't combined, see if we need to add a unconditional
- // branch to the 'false' block.
- if (NeedBr1 && !canFallThroughTo(BBI.BB, BBI2->BB)) {
- InsertUncondBranch(BBI.BB, BBI2->BB, TII);
- BBI1->HasFallThrough = false;
+ // Predicate the 'true' block after removing its branch.
+ BBI1->NonPredSize -= TII->RemoveBranch(*BBI1->BB);
+ DI1 = BBI1->BB->end();
+ for (unsigned i = 0; i != NumDups2; ) {
+ // NumDups2 only counted non-dbg_value instructions, so this won't
+ // run off the head of the list.
+ assert (DI1 != BBI1->BB->begin());
+ --DI1;
+ // skip dbg_value instructions
+ if (!DI1->isDebugValue())
+ ++i;
}
+ BBI1->BB->erase(DI1, BBI1->BB->end());
+ PredicateBlock(*BBI1, BBI1->BB->end(), *Cond1, Redefs);
- // If the if-converted block fallthrough or unconditionally branch into the
- // tail block, and the tail block does not have other predecessors, then
- // fold the tail block in as well.
- BBInfo *CvtBBI = NeedBr1 ? BBI2 : &BBI;
- if (BBI.TailBB &&
- BBI.TailBB->pred_size() == 1 && CvtBBI->BB->succ_size() == 1) {
- CvtBBI->NonPredSize -= TII->RemoveBranch(*CvtBBI->BB);
- BBInfo TailBBI = BBAnalysis[BBI.TailBB->getNumber()];
- MergeBlocks(*CvtBBI, TailBBI);
- TailBBI.IsDone = true;
+ // Predicate the 'false' block.
+ BBI2->NonPredSize -= TII->RemoveBranch(*BBI2->BB);
+ DI2 = BBI2->BB->end();
+ while (NumDups2 != 0) {
+ // NumDups2 only counted non-dbg_value instructions, so this won't
+ // run off the head of the list.
+ assert (DI2 != BBI2->BB->begin());
+ --DI2;
+ // skip dbg_value instructions
+ if (!DI2->isDebugValue())
+ --NumDups2;
+ }
+ PredicateBlock(*BBI2, DI2, *Cond2, Redefs);
+
+ // Merge the true block into the entry of the diamond.
+ MergeBlocks(BBI, *BBI1, TailBB == 0);
+ MergeBlocks(BBI, *BBI2, TailBB == 0);
+
+ // If the if-converted block falls through or unconditionally branches into
+ // the tail block, and the tail block does not have other predecessors, then
+ // fold the tail block in as well. Otherwise, unless it falls through to the
+ // tail, add a unconditional branch to it.
+ if (TailBB) {
+ BBInfo TailBBI = BBAnalysis[TailBB->getNumber()];
+ bool CanMergeTail = !TailBBI.HasFallThrough;
+ // There may still be a fall-through edge from BBI1 or BBI2 to TailBB;
+ // check if there are any other predecessors besides those.
+ unsigned NumPreds = TailBB->pred_size();
+ if (NumPreds > 1)
+ CanMergeTail = false;
+ else if (NumPreds == 1 && CanMergeTail) {
+ MachineBasicBlock::pred_iterator PI = TailBB->pred_begin();
+ if (*PI != BBI1->BB && *PI != BBI2->BB)
+ CanMergeTail = false;
+ }
+ if (CanMergeTail) {
+ MergeBlocks(BBI, TailBBI);
+ TailBBI.IsDone = true;
+ } else {
+ BBI.BB->addSuccessor(TailBB);
+ InsertUncondBranch(BBI.BB, TailBB, TII);
+ BBI.HasFallThrough = false;
+ }
}
+ // RemoveExtraEdges won't work if the block has an unanalyzable branch,
+ // which can happen here if TailBB is unanalyzable and is merged, so
+ // explicitly remove BBI1 and BBI2 as successors.
+ BBI.BB->removeSuccessor(BBI1->BB);
+ BBI.BB->removeSuccessor(BBI2->BB);
RemoveExtraEdges(BBI);
// Update block info.
BBI.IsDone = TrueBBI.IsDone = FalseBBI.IsDone = true;
+ InvalidatePreds(BBI.BB);
// FIXME: Must maintain LiveIns.
return true;
}
-/// PredicateBlock - Predicate every instruction in the block with the specified
-/// condition. If IgnoreTerm is true, skip over all terminator instructions.
+/// PredicateBlock - Predicate instructions from the start of the block to the
+/// specified end with the specified condition.
void IfConverter::PredicateBlock(BBInfo &BBI,
- std::vector<MachineOperand> &Cond,
- bool IgnoreTerm) {
- for (MachineBasicBlock::iterator I = BBI.BB->begin(), E = BBI.BB->end();
- I != E; ++I) {
- if (IgnoreTerm && TII->isTerminatorInstr(I->getOpcode()))
- continue;
- if (TII->isPredicated(I))
+ MachineBasicBlock::iterator E,
+ SmallVectorImpl<MachineOperand> &Cond,
+ SmallSet<unsigned, 4> &Redefs) {
+ for (MachineBasicBlock::iterator I = BBI.BB->begin(); I != E; ++I) {
+ if (I->isDebugValue() || TII->isPredicated(I))
continue;
if (!TII->PredicateInstruction(I, Cond)) {
- cerr << "Unable to predicate " << *I << "!\n";
- abort();
+#ifndef NDEBUG
+ dbgs() << "Unable to predicate " << *I << "!\n";
+#endif
+ llvm_unreachable(0);
}
+
+ // If the predicated instruction now redefines a register as the result of
+ // if-conversion, add an implicit kill.
+ UpdatePredRedefs(I, Redefs, TRI, true);
}
std::copy(Cond.begin(), Cond.end(), std::back_inserter(BBI.Predicate));
BBI.IsAnalyzed = false;
BBI.NonPredSize = 0;
- NumIfConvBBs++;
+ ++NumIfConvBBs;
}
/// CopyAndPredicateBlock - Copy and predicate instructions from source BB to
/// the destination block. Skip end of block branches if IgnoreBr is true.
void IfConverter::CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI,
- std::vector<MachineOperand> &Cond,
+ SmallVectorImpl<MachineOperand> &Cond,
+ SmallSet<unsigned, 4> &Redefs,
bool IgnoreBr) {
+ MachineFunction &MF = *ToBBI.BB->getParent();
+
for (MachineBasicBlock::iterator I = FromBBI.BB->begin(),
E = FromBBI.BB->end(); I != E; ++I) {
- const TargetInstrDescriptor *TID = I->getInstrDescriptor();
- bool isPredicated = TII->isPredicated(I);
+ const TargetInstrDesc &TID = I->getDesc();
// Do not copy the end of the block branches.
- if (IgnoreBr && !isPredicated && (TID->Flags & M_BRANCH_FLAG) != 0)
+ if (IgnoreBr && TID.isBranch())
break;
- MachineInstr *MI = I->clone();
+ MachineInstr *MI = MF.CloneMachineInstr(I);
ToBBI.BB->insert(ToBBI.BB->end(), MI);
ToBBI.NonPredSize++;
- if (!isPredicated)
+ if (!TII->isPredicated(I) && !MI->isDebugValue()) {
if (!TII->PredicateInstruction(MI, Cond)) {
- cerr << "Unable to predicate " << *MI << "!\n";
- abort();
+#ifndef NDEBUG
+ dbgs() << "Unable to predicate " << *I << "!\n";
+#endif
+ llvm_unreachable(0);
}
+ }
+
+ // If the predicated instruction now redefines a register as the result of
+ // if-conversion, add an implicit kill.
+ UpdatePredRedefs(MI, Redefs, TRI, true);
+ }
+
+ if (!IgnoreBr) {
+ std::vector<MachineBasicBlock *> Succs(FromBBI.BB->succ_begin(),
+ FromBBI.BB->succ_end());
+ MachineBasicBlock *NBB = getNextBlock(FromBBI.BB);
+ MachineBasicBlock *FallThrough = FromBBI.HasFallThrough ? NBB : NULL;
+
+ for (unsigned i = 0, e = Succs.size(); i != e; ++i) {
+ MachineBasicBlock *Succ = Succs[i];
+ // Fallthrough edge can't be transferred.
+ if (Succ == FallThrough)
+ continue;
+ ToBBI.BB->addSuccessor(Succ);
+ }
}
std::copy(FromBBI.Predicate.begin(), FromBBI.Predicate.end(),
ToBBI.ClobbersPred |= FromBBI.ClobbersPred;
ToBBI.IsAnalyzed = false;
- NumDupBBs++;
+ ++NumDupBBs;
}
/// MergeBlocks - Move all instructions from FromBB to the end of ToBB.
-///
-void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI) {
+/// This will leave FromBB as an empty block, so remove all of its
+/// successor edges except for the fall-through edge. If AddEdges is true,
+/// i.e., when FromBBI's branch is being moved, add those successor edges to
+/// ToBBI.
+void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI, bool AddEdges) {
ToBBI.BB->splice(ToBBI.BB->end(),
FromBBI.BB, FromBBI.BB->begin(), FromBBI.BB->end());
- // Redirect all branches to FromBB to ToBB.
- std::vector<MachineBasicBlock *> Preds(FromBBI.BB->pred_begin(),
- FromBBI.BB->pred_end());
- for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
- MachineBasicBlock *Pred = Preds[i];
- if (Pred == ToBBI.BB)
- continue;
- Pred->ReplaceUsesOfBlockWith(FromBBI.BB, ToBBI.BB);
- }
-
std::vector<MachineBasicBlock *> Succs(FromBBI.BB->succ_begin(),
FromBBI.BB->succ_end());
MachineBasicBlock *NBB = getNextBlock(FromBBI.BB);
if (Succ == FallThrough)
continue;
FromBBI.BB->removeSuccessor(Succ);
- if (!ToBBI.BB->isSuccessor(Succ))
+ if (AddEdges)
ToBBI.BB->addSuccessor(Succ);
}
- // Now FromBBI always fall through to the next block!
- if (NBB)
+ // Now FromBBI always falls through to the next block!
+ if (NBB && !FromBBI.BB->isSuccessor(NBB))
FromBBI.BB->addSuccessor(NBB);
std::copy(FromBBI.Predicate.begin(), FromBBI.Predicate.end(),
projects / oota-llvm.git / blobdiff