mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-17 21:29:20 +00:00
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37344 91177308-0d34-0410-b5e6-96231b3b80d8
621 lines
21 KiB
C++
621 lines
21 KiB
C++
//===-- IfConversion.cpp - Machine code if conversion pass. ---------------===//
|
|
//
|
|
// 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 implements the machine instruction level if-conversion pass.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define DEBUG_TYPE "ifconversion"
|
|
#include "llvm/CodeGen/Passes.h"
|
|
#include "llvm/CodeGen/MachineModuleInfo.h"
|
|
#include "llvm/CodeGen/MachineFunctionPass.h"
|
|
#include "llvm/Target/TargetInstrInfo.h"
|
|
#include "llvm/Target/TargetLowering.h"
|
|
#include "llvm/Target/TargetMachine.h"
|
|
#include "llvm/Support/Debug.h"
|
|
#include "llvm/ADT/DepthFirstIterator.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
using namespace llvm;
|
|
|
|
STATISTIC(NumIfConvBBs, "Number of if-converted blocks");
|
|
|
|
namespace {
|
|
class IfConverter : public MachineFunctionPass {
|
|
enum BBICKind {
|
|
ICNotAnalyzed, // BB has not been analyzed.
|
|
ICReAnalyze, // BB must be re-analyzed.
|
|
ICNotClassfied, // BB data valid, but not classified.
|
|
ICEarlyExit, // BB is entry of an early-exit sub-CFG.
|
|
ICTriangle, // BB is entry of a triangle sub-CFG.
|
|
ICDiamond, // BB is entry of a diamond sub-CFG.
|
|
ICChild, // BB is part of the sub-CFG that'll be predicated.
|
|
ICDead // BB has been converted and merged, it's now dead.
|
|
};
|
|
|
|
/// BBInfo - One per MachineBasicBlock, this is used to cache the result
|
|
/// if-conversion feasibility analysis. This includes results from
|
|
/// TargetInstrInfo::AnalyzeBranch() (i.e. TBB, FBB, and Cond), and its
|
|
/// classification, and common tail block of its successors (if it's a
|
|
/// diamond shape), its size, whether it's predicable, and whether any
|
|
/// instruction can clobber the 'would-be' predicate.
|
|
///
|
|
/// Kind - Type of block. See BBICKind.
|
|
/// NonPredSize - Number of non-predicated instructions.
|
|
/// isPredicable - Is it predicable. (FIXME: Remove.)
|
|
/// hasEarlyExit - Ends with a return, indirect jump or br to jumptable.
|
|
/// ModifyPredicate - FIXME: Not used right now. True if BB would modify
|
|
/// the predicate (e.g. has cmp, call, etc.)
|
|
/// BB - Corresponding MachineBasicBlock.
|
|
/// TrueBB / FalseBB- See AnalyzeBranch().
|
|
/// BrCond - Conditions for end of block conditional branches.
|
|
/// Predicate - Predicate used in the BB.
|
|
struct BBInfo {
|
|
BBICKind Kind;
|
|
unsigned NonPredSize;
|
|
bool isPredicable;
|
|
bool hasEarlyExit;
|
|
bool ModifyPredicate;
|
|
MachineBasicBlock *BB;
|
|
MachineBasicBlock *TrueBB;
|
|
MachineBasicBlock *FalseBB;
|
|
MachineBasicBlock *TailBB;
|
|
std::vector<MachineOperand> BrCond;
|
|
std::vector<MachineOperand> Predicate;
|
|
BBInfo() : Kind(ICNotAnalyzed), NonPredSize(0), isPredicable(false),
|
|
hasEarlyExit(false), ModifyPredicate(false),
|
|
BB(0), TrueBB(0), FalseBB(0), TailBB(0) {}
|
|
};
|
|
|
|
/// BBAnalysis - Results of if-conversion feasibility analysis indexed by
|
|
/// basic block number.
|
|
std::vector<BBInfo> BBAnalysis;
|
|
|
|
const TargetLowering *TLI;
|
|
const TargetInstrInfo *TII;
|
|
bool MadeChange;
|
|
public:
|
|
static char ID;
|
|
IfConverter() : MachineFunctionPass((intptr_t)&ID) {}
|
|
|
|
virtual bool runOnMachineFunction(MachineFunction &MF);
|
|
virtual const char *getPassName() const { return "If converter"; }
|
|
|
|
private:
|
|
void StructuralAnalysis(MachineBasicBlock *BB);
|
|
void FeasibilityAnalysis(BBInfo &BBI,
|
|
std::vector<MachineOperand> &Cond);
|
|
void AnalyzeBlocks(MachineFunction &MF,
|
|
std::vector<BBInfo*> &Candidates);
|
|
void InvalidatePreds(MachineBasicBlock *BB);
|
|
bool IfConvertEarlyExit(BBInfo &BBI);
|
|
bool IfConvertTriangle(BBInfo &BBI);
|
|
bool IfConvertDiamond(BBInfo &BBI);
|
|
void PredicateBlock(BBInfo &BBI,
|
|
std::vector<MachineOperand> &Cond,
|
|
bool IgnoreTerm = false);
|
|
void MergeBlocks(BBInfo &TrueBBI, BBInfo &FalseBBI);
|
|
};
|
|
char IfConverter::ID = 0;
|
|
}
|
|
|
|
FunctionPass *llvm::createIfConverterPass() { return new IfConverter(); }
|
|
|
|
bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
|
|
TLI = MF.getTarget().getTargetLowering();
|
|
TII = MF.getTarget().getInstrInfo();
|
|
if (!TII) return false;
|
|
|
|
MF.RenumberBlocks();
|
|
unsigned NumBBs = MF.getNumBlockIDs();
|
|
BBAnalysis.resize(NumBBs);
|
|
|
|
std::vector<BBInfo*> Candidates;
|
|
MadeChange = false;
|
|
while (true) {
|
|
bool Change = false;
|
|
|
|
// Do an intial analysis for each basic block and finding all the potential
|
|
// candidates to perform if-convesion.
|
|
AnalyzeBlocks(MF, Candidates);
|
|
while (!Candidates.empty()) {
|
|
BBInfo &BBI = *Candidates.back();
|
|
Candidates.pop_back();
|
|
switch (BBI.Kind) {
|
|
default: assert(false && "Unexpected!");
|
|
break;
|
|
case ICEarlyExit:
|
|
Change |= IfConvertEarlyExit(BBI);
|
|
break;
|
|
case ICTriangle:
|
|
Change |= IfConvertTriangle(BBI);
|
|
break;
|
|
case ICDiamond:
|
|
Change |= IfConvertDiamond(BBI);
|
|
break;
|
|
}
|
|
}
|
|
|
|
MadeChange |= Change;
|
|
if (!Change)
|
|
break;
|
|
}
|
|
|
|
BBAnalysis.clear();
|
|
|
|
return MadeChange;
|
|
}
|
|
|
|
static MachineBasicBlock *findFalseBlock(MachineBasicBlock *BB,
|
|
MachineBasicBlock *TrueBB) {
|
|
for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
|
|
E = BB->succ_end(); SI != E; ++SI) {
|
|
MachineBasicBlock *SuccBB = *SI;
|
|
if (SuccBB != TrueBB)
|
|
return SuccBB;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/// StructuralAnalysis - Analyze the structure of the sub-CFG starting from
|
|
/// the specified block. Record its successors and whether it looks like an
|
|
/// if-conversion candidate.
|
|
void IfConverter::StructuralAnalysis(MachineBasicBlock *BB) {
|
|
BBInfo &BBI = BBAnalysis[BB->getNumber()];
|
|
|
|
if (BBI.Kind != ICReAnalyze) {
|
|
if (BBI.Kind != ICNotAnalyzed)
|
|
return; // Already analyzed.
|
|
BBI.BB = BB;
|
|
BBI.NonPredSize = std::distance(BB->begin(), BB->end());
|
|
}
|
|
|
|
// Look for 'root' of a simple (non-nested) triangle or diamond.
|
|
BBI.Kind = ICNotClassfied;
|
|
bool CanAnalyze = !TII->AnalyzeBranch(*BB, BBI.TrueBB, BBI.FalseBB,
|
|
BBI.BrCond);
|
|
// Does it end with a return, indirect jump, or jumptable branch?
|
|
BBI.hasEarlyExit = TII->BlockHasNoFallThrough(*BB) && !BBI.TrueBB;
|
|
if (!CanAnalyze || !BBI.TrueBB || BBI.BrCond.size() == 0)
|
|
return;
|
|
|
|
// Not a candidate if 'true' block is going to be if-converted.
|
|
StructuralAnalysis(BBI.TrueBB);
|
|
BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
|
|
if (TrueBBI.Kind != ICNotClassfied)
|
|
return;
|
|
|
|
// TODO: Only handle very simple cases for now.
|
|
if (TrueBBI.FalseBB || TrueBBI.BrCond.size())
|
|
return;
|
|
|
|
// No false branch. This BB must end with a conditional branch and a
|
|
// fallthrough.
|
|
if (!BBI.FalseBB)
|
|
BBI.FalseBB = findFalseBlock(BB, BBI.TrueBB);
|
|
assert(BBI.FalseBB && "Expected to find the fallthrough block!");
|
|
|
|
// Not a candidate if 'false' block is going to be if-converted.
|
|
StructuralAnalysis(BBI.FalseBB);
|
|
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
|
|
if (FalseBBI.Kind != ICNotClassfied)
|
|
return;
|
|
|
|
// TODO: Only handle very simple cases for now.
|
|
if (FalseBBI.FalseBB || FalseBBI.BrCond.size())
|
|
return;
|
|
|
|
unsigned TrueNumPreds = BBI.TrueBB->pred_size();
|
|
unsigned FalseNumPreds = BBI.FalseBB->pred_size();
|
|
if ((TrueBBI.hasEarlyExit && TrueNumPreds <= 1) &&
|
|
!(FalseBBI.hasEarlyExit && FalseNumPreds <=1)) {
|
|
BBI.Kind = ICEarlyExit;
|
|
TrueBBI.Kind = ICChild;
|
|
} else if (!(TrueBBI.hasEarlyExit && TrueNumPreds <= 1) &&
|
|
(FalseBBI.hasEarlyExit && FalseNumPreds <=1)) {
|
|
BBI.Kind = ICEarlyExit;
|
|
FalseBBI.Kind = ICChild;
|
|
} else if (TrueBBI.TrueBB && TrueBBI.TrueBB == BBI.FalseBB) {
|
|
// Triangle:
|
|
// EBB
|
|
// | \_
|
|
// | |
|
|
// | TBB
|
|
// | /
|
|
// FBB
|
|
BBI.Kind = ICTriangle;
|
|
TrueBBI.Kind = FalseBBI.Kind = ICChild;
|
|
} else if (TrueBBI.TrueBB == FalseBBI.TrueBB &&
|
|
TrueNumPreds <= 1 && FalseNumPreds <= 1) {
|
|
// Diamond:
|
|
// EBB
|
|
// / \_
|
|
// | |
|
|
// TBB FBB
|
|
// \ /
|
|
// TailBB
|
|
// Note MBB can be empty in case both TBB and FBB are return blocks.
|
|
BBI.Kind = ICDiamond;
|
|
TrueBBI.Kind = FalseBBI.Kind = ICChild;
|
|
BBI.TailBB = TrueBBI.TrueBB;
|
|
}
|
|
return;
|
|
}
|
|
|
|
/// FeasibilityAnalysis - 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 instruction which can clobber a
|
|
/// predicate (e.g. condition code register). If so, the block is not
|
|
/// predicable unless it's the last instruction. Note, this function assumes
|
|
/// all the terminator instructions can be converted or deleted so it ignore
|
|
/// them.
|
|
void IfConverter::FeasibilityAnalysis(BBInfo &BBI,
|
|
std::vector<MachineOperand> &Cond) {
|
|
if (BBI.NonPredSize == 0 || BBI.NonPredSize > TLI->getIfCvtBlockSizeLimit())
|
|
return;
|
|
|
|
for (MachineBasicBlock::iterator I = BBI.BB->begin(), E = BBI.BB->end();
|
|
I != E; ++I) {
|
|
// TODO: check if instruction clobbers predicate.
|
|
if (TII->isTerminatorInstr(I->getOpcode()))
|
|
break;
|
|
if (!I->isPredicable())
|
|
return;
|
|
}
|
|
|
|
if (BBI.Predicate.size() && !TII->SubsumesPredicate(BBI.Predicate, Cond))
|
|
return;
|
|
|
|
BBI.isPredicable = true;
|
|
}
|
|
|
|
/// AnalyzeBlocks - Analyze all blocks and find entries for all
|
|
/// if-conversion candidates.
|
|
void IfConverter::AnalyzeBlocks(MachineFunction &MF,
|
|
std::vector<BBInfo*> &Candidates) {
|
|
std::set<MachineBasicBlock*> Visited;
|
|
MachineBasicBlock *Entry = MF.begin();
|
|
for (df_ext_iterator<MachineBasicBlock*> DFI = df_ext_begin(Entry, Visited),
|
|
E = df_ext_end(Entry, Visited); DFI != E; ++DFI) {
|
|
MachineBasicBlock *BB = *DFI;
|
|
StructuralAnalysis(BB);
|
|
BBInfo &BBI = BBAnalysis[BB->getNumber()];
|
|
switch (BBI.Kind) {
|
|
default: break;
|
|
case ICEarlyExit:
|
|
case ICTriangle:
|
|
case ICDiamond:
|
|
Candidates.push_back(&BBI);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// TransferPreds - Transfer all the predecessors of FromBB to ToBB.
|
|
///
|
|
static void TransferPreds(MachineBasicBlock *ToBB, MachineBasicBlock *FromBB) {
|
|
std::vector<MachineBasicBlock*> Preds(FromBB->pred_begin(),
|
|
FromBB->pred_end());
|
|
for (unsigned i = 0, e = Preds.size(); i != e; ++i) {
|
|
MachineBasicBlock *Pred = Preds[i];
|
|
Pred->removeSuccessor(FromBB);
|
|
if (!Pred->isSuccessor(ToBB))
|
|
Pred->addSuccessor(ToBB);
|
|
}
|
|
}
|
|
|
|
/// TransferSuccs - Transfer all the successors of FromBB to ToBB.
|
|
///
|
|
static void TransferSuccs(MachineBasicBlock *ToBB, MachineBasicBlock *FromBB) {
|
|
std::vector<MachineBasicBlock*> Succs(FromBB->succ_begin(),
|
|
FromBB->succ_end());
|
|
for (unsigned i = 0, e = Succs.size(); i != e; ++i) {
|
|
MachineBasicBlock *Succ = Succs[i];
|
|
FromBB->removeSuccessor(Succ);
|
|
if (!ToBB->isSuccessor(Succ))
|
|
ToBB->addSuccessor(Succ);
|
|
}
|
|
}
|
|
|
|
/// isNextBlock - Returns true if ToBB the next basic block after BB.
|
|
///
|
|
static bool isNextBlock(MachineBasicBlock *BB, MachineBasicBlock *ToBB) {
|
|
MachineFunction::iterator Fallthrough = BB;
|
|
return MachineFunction::iterator(ToBB) == ++Fallthrough;
|
|
}
|
|
|
|
/// InvalidatePreds - Invalidate predecessor BB info so it would be re-analyzed
|
|
/// to determine if it can be if-converted.
|
|
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()];
|
|
PBBI.Kind = ICReAnalyze;
|
|
}
|
|
}
|
|
|
|
/// InsertUncondBranch - Inserts an unconditional branch from BB to ToBB.
|
|
///
|
|
static void InsertUncondBranch(MachineBasicBlock *BB, MachineBasicBlock *ToBB,
|
|
const TargetInstrInfo *TII) {
|
|
std::vector<MachineOperand> NoCond;
|
|
TII->InsertBranch(*BB, ToBB, NULL, NoCond);
|
|
}
|
|
|
|
/// IfConvertEarlyExit - If convert a early exit sub-CFG.
|
|
///
|
|
bool IfConverter::IfConvertEarlyExit(BBInfo &BBI) {
|
|
BBI.Kind = ICNotClassfied;
|
|
|
|
BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
|
|
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
|
|
BBInfo *CvtBBI = &TrueBBI;
|
|
BBInfo *NextBBI = &FalseBBI;
|
|
|
|
bool ReserveCond = false;
|
|
if (TrueBBI.Kind != ICChild) {
|
|
std::swap(CvtBBI, NextBBI);
|
|
ReserveCond = true;
|
|
}
|
|
|
|
std::vector<MachineOperand> NewCond(BBI.BrCond);
|
|
if (ReserveCond)
|
|
TII->ReverseBranchCondition(NewCond);
|
|
FeasibilityAnalysis(*CvtBBI, NewCond);
|
|
if (!CvtBBI->isPredicable)
|
|
return false;
|
|
|
|
PredicateBlock(*CvtBBI, NewCond);
|
|
|
|
// Merge converted block into entry block. Also convert the end of the
|
|
// block conditional branch (to the non-converted block) into an
|
|
// unconditional one.
|
|
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
|
|
MergeBlocks(BBI, *CvtBBI);
|
|
if (!isNextBlock(BBI.BB, NextBBI->BB))
|
|
InsertUncondBranch(BBI.BB, NextBBI->BB, TII);
|
|
std::copy(NewCond.begin(), NewCond.end(), std::back_inserter(BBI.Predicate));
|
|
|
|
// Update block info. BB can be iteratively if-converted.
|
|
BBI.Kind = ICNotAnalyzed;
|
|
BBI.TrueBB = BBI.FalseBB = NULL;
|
|
BBI.BrCond.clear();
|
|
TII->AnalyzeBranch(*BBI.BB, BBI.TrueBB, BBI.FalseBB, BBI.BrCond);
|
|
InvalidatePreds(BBI.BB);
|
|
CvtBBI->Kind = ICDead;
|
|
|
|
// FIXME: Must maintain LiveIns.
|
|
NumIfConvBBs++;
|
|
return true;
|
|
}
|
|
|
|
/// IfConvertTriangle - If convert a triangle sub-CFG.
|
|
///
|
|
bool IfConverter::IfConvertTriangle(BBInfo &BBI) {
|
|
BBI.Kind = ICNotClassfied;
|
|
|
|
BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
|
|
FeasibilityAnalysis(TrueBBI, BBI.BrCond);
|
|
if (!TrueBBI.isPredicable)
|
|
return false;
|
|
|
|
// Predicate the 'true' block after removing its branch.
|
|
TrueBBI.NonPredSize -= TII->RemoveBranch(*BBI.TrueBB);
|
|
PredicateBlock(TrueBBI, BBI.BrCond);
|
|
|
|
// Join the 'true' and 'false' blocks by copying the instructions
|
|
// from the 'false' block to the 'true' block.
|
|
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
|
|
MergeBlocks(TrueBBI, FalseBBI);
|
|
|
|
// Now merge the entry of the triangle with the true block.
|
|
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
|
|
MergeBlocks(BBI, TrueBBI);
|
|
std::copy(BBI.BrCond.begin(), BBI.BrCond.end(),
|
|
std::back_inserter(BBI.Predicate));
|
|
|
|
// Update block info. BB can be iteratively if-converted.
|
|
BBI.Kind = ICNotClassfied;
|
|
BBI.TrueBB = BBI.FalseBB = NULL;
|
|
BBI.BrCond.clear();
|
|
TII->AnalyzeBranch(*BBI.BB, BBI.TrueBB, BBI.FalseBB, BBI.BrCond);
|
|
TrueBBI.Kind = ICDead;
|
|
|
|
// FIXME: Must maintain LiveIns.
|
|
NumIfConvBBs++;
|
|
return true;
|
|
}
|
|
|
|
/// IfConvertDiamond - If convert a diamond sub-CFG.
|
|
///
|
|
bool IfConverter::IfConvertDiamond(BBInfo &BBI) {
|
|
BBI.Kind = ICNotClassfied;
|
|
|
|
bool TrueNeedBr;
|
|
bool FalseNeedBr;
|
|
BBInfo &TrueBBI = BBAnalysis[BBI.TrueBB->getNumber()];
|
|
BBInfo &FalseBBI = BBAnalysis[BBI.FalseBB->getNumber()];
|
|
FeasibilityAnalysis(TrueBBI, BBI.BrCond);
|
|
std::vector<MachineOperand> RevCond(BBI.BrCond);
|
|
TII->ReverseBranchCondition(RevCond);
|
|
FeasibilityAnalysis(FalseBBI, RevCond);
|
|
|
|
SmallVector<MachineInstr*, 2> Dups;
|
|
bool Proceed = TrueBBI.isPredicable && FalseBBI.isPredicable;
|
|
if (Proceed) {
|
|
// 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.
|
|
TrueNeedBr = !TrueBBI.TrueBB && BBI.TrueBB->succ_size();
|
|
FalseNeedBr = !FalseBBI.TrueBB && BBI.FalseBB->succ_size();
|
|
if (TrueNeedBr && TrueBBI.ModifyPredicate) {
|
|
TrueBBI.isPredicable = false;
|
|
Proceed = false;
|
|
}
|
|
if (FalseNeedBr && FalseBBI.ModifyPredicate) {
|
|
FalseBBI.isPredicable = false;
|
|
Proceed = false;
|
|
}
|
|
|
|
if (Proceed) {
|
|
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->isPredicable() && !FT->isPredicable()) {
|
|
Proceed = false;
|
|
break; // Can't if-convert. Abort!
|
|
}
|
|
++TT;
|
|
++FT;
|
|
}
|
|
|
|
// One of the two pathes have more terminators, make sure they are
|
|
// all predicable.
|
|
while (Proceed && TT != BBI.TrueBB->end())
|
|
if (!TT->isPredicable()) {
|
|
Proceed = false;
|
|
break; // Can't if-convert. Abort!
|
|
}
|
|
while (Proceed && FT != BBI.FalseBB->end())
|
|
if (!FT->isPredicable()) {
|
|
Proceed = false;
|
|
break; // Can't if-convert. Abort!
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if (!Proceed)
|
|
return false;
|
|
|
|
// Remove the duplicated instructions from the 'true' block.
|
|
for (unsigned i = 0, e = Dups.size(); i != e; ++i) {
|
|
Dups[i]->eraseFromParent();
|
|
--TrueBBI.NonPredSize;
|
|
}
|
|
|
|
// Predicate the 'true' block after removing its branch.
|
|
TrueBBI.NonPredSize -= TII->RemoveBranch(*BBI.TrueBB);
|
|
PredicateBlock(TrueBBI, BBI.BrCond);
|
|
|
|
// Predicate the 'false' block.
|
|
PredicateBlock(FalseBBI, RevCond, true);
|
|
|
|
// 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.
|
|
BBInfo *CvtBBI;
|
|
if (!TrueBBI.ModifyPredicate) {
|
|
// Add a conditional branch from 'true' to 'true' successor if needed.
|
|
if (TrueNeedBr)
|
|
TII->InsertBranch(*BBI.TrueBB, *BBI.TrueBB->succ_begin(), NULL,
|
|
BBI.BrCond);
|
|
// Add an unconditional branch from 'false' to to 'false' successor if it
|
|
// will not be the fallthrough block.
|
|
if (FalseNeedBr &&
|
|
!isNextBlock(BBI.BB, *BBI.FalseBB->succ_begin()))
|
|
InsertUncondBranch(BBI.FalseBB, *BBI.FalseBB->succ_begin(), TII);
|
|
MergeBlocks(TrueBBI, FalseBBI);
|
|
CvtBBI = &TrueBBI;
|
|
} else {
|
|
// Add a conditional branch from 'false' to 'false' successor if needed.
|
|
if (FalseNeedBr)
|
|
TII->InsertBranch(*BBI.FalseBB, *BBI.FalseBB->succ_begin(), NULL,
|
|
RevCond);
|
|
// Add an unconditional branch from 'true' to to 'true' successor if it
|
|
// will not be the fallthrough block.
|
|
if (TrueNeedBr &&
|
|
!isNextBlock(BBI.BB, *BBI.TrueBB->succ_begin()))
|
|
InsertUncondBranch(BBI.TrueBB, *BBI.TrueBB->succ_begin(), TII);
|
|
MergeBlocks(FalseBBI, TrueBBI);
|
|
CvtBBI = &FalseBBI;
|
|
}
|
|
|
|
// Remove the conditional branch from entry to the blocks.
|
|
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
|
|
|
|
bool OkToIfcvt = true;
|
|
// Merge the combined block into the entry of the diamond if the entry
|
|
// block is its only predecessor. Otherwise, insert an unconditional
|
|
// branch from entry to the if-converted block.
|
|
if (CvtBBI->BB->pred_size() == 1) {
|
|
MergeBlocks(BBI, *CvtBBI);
|
|
CvtBBI = &BBI;
|
|
OkToIfcvt = false;
|
|
} else
|
|
InsertUncondBranch(BBI.BB, CvtBBI->BB, TII);
|
|
|
|
// If the if-converted block fallthrough into the tail block, then
|
|
// fold the tail block in as well.
|
|
if (BBI.TailBB && CvtBBI->BB->succ_size() == 1) {
|
|
CvtBBI->NonPredSize -= TII->RemoveBranch(*CvtBBI->BB);
|
|
BBInfo TailBBI = BBAnalysis[BBI.TailBB->getNumber()];
|
|
MergeBlocks(*CvtBBI, TailBBI);
|
|
TailBBI.Kind = ICDead;
|
|
}
|
|
|
|
// Update block info. BB may be iteratively if-converted.
|
|
if (OkToIfcvt) {
|
|
BBI.Kind = ICNotClassfied;
|
|
BBI.TrueBB = BBI.FalseBB = NULL;
|
|
BBI.BrCond.clear();
|
|
TII->AnalyzeBranch(*BBI.BB, BBI.TrueBB, BBI.FalseBB, BBI.BrCond);
|
|
InvalidatePreds(BBI.BB);
|
|
}
|
|
TrueBBI.Kind = ICDead;
|
|
FalseBBI.Kind = ICDead;
|
|
|
|
// FIXME: Must maintain LiveIns.
|
|
NumIfConvBBs += 2;
|
|
return true;
|
|
}
|
|
|
|
/// PredicateBlock - Predicate every instruction in the block with the specified
|
|
/// condition. If IgnoreTerm is true, skip over all terminator instructions.
|
|
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) {
|
|
MachineInstr *MI = I;
|
|
if (IgnoreTerm && TII->isTerminatorInstr(MI->getOpcode()))
|
|
continue;
|
|
if (TII->isPredicated(MI))
|
|
continue;
|
|
if (!TII->PredicateInstruction(MI, Cond)) {
|
|
cerr << "Unable to predication " << *I << "!\n";
|
|
abort();
|
|
}
|
|
}
|
|
|
|
BBI.NonPredSize = 0;
|
|
}
|
|
|
|
/// MergeBlocks - Move all instructions from FromBB to the end of ToBB.
|
|
///
|
|
void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI) {
|
|
ToBBI.BB->splice(ToBBI.BB->end(),
|
|
FromBBI.BB, FromBBI.BB->begin(), FromBBI.BB->end());
|
|
|
|
// If FromBBI is previously a successor, remove it from ToBBI's successor
|
|
// list and update its TrueBB / FalseBB field if needed.
|
|
if (ToBBI.BB->isSuccessor(FromBBI.BB))
|
|
ToBBI.BB->removeSuccessor(FromBBI.BB);
|
|
|
|
// Transfer preds / succs and update size.
|
|
TransferPreds(ToBBI.BB, FromBBI.BB);
|
|
TransferSuccs(ToBBI.BB, FromBBI.BB);
|
|
ToBBI.NonPredSize += FromBBI.NonPredSize;
|
|
FromBBI.NonPredSize = 0;
|
|
}
|