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Move most of the pre BB code to TailDuplicateAndUpdate. Change the 

HasIndirectbr variable to be just that. No functionality change.

llvm-svn: 134371
This commit is contained in:
Rafael Espindola 2011-07-04 01:21:42 +00:00
parent 79dc4e7709
commit f9f012ea88
1 changed files with 125 additions and 112 deletions
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97
llvm/lib/CodeGen/TailDuplication.cpp
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@ -102,9 +102,15 @@ namespace {
SmallVector<MachineBasicBlock*, 8> &TDBBs,
const DenseSet<unsigned> &RegsUsedByPhi,
SmallVector<MachineInstr*, 16> &Copies);
bool TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
bool TailDuplicate(MachineBasicBlock *TailBB,
bool IsSimple,
MachineFunction &MF,
SmallVector<MachineBasicBlock*, 8> &TDBBs,
SmallVector<MachineInstr*, 16> &Copies);
bool TailDuplicateAndUpdate(MachineBasicBlock *MBB,
bool IsSimple,
MachineFunction &MF);
void RemoveDeadBlock(MachineBasicBlock *MBB);
};
@ -175,37 +181,25 @@ static void VerifyPHIs(MachineFunction &MF, bool CheckExtra) {
}
}
/// TailDuplicateBlocks - Look for small blocks that are unconditionally
/// branched to and do not fall through. Tail-duplicate their instructions
/// into their predecessors to eliminate (dynamic) branches.
bool TailDuplicatePass::TailDuplicateBlocks(MachineFunction &MF) {
bool MadeChange = false;
if (PreRegAlloc && TailDupVerify) {
DEBUG(dbgs() << "\n*** Before tail-duplicating\n");
VerifyPHIs(MF, true);
}
SmallVector<MachineInstr*, 8> NewPHIs;
MachineSSAUpdater SSAUpdate(MF, &NewPHIs);
for (MachineFunction::iterator I = ++MF.begin(), E = MF.end(); I != E; ) {
MachineBasicBlock *MBB = I++;
if (NumTails == TailDupLimit)
break;
/// TailDuplicateAndUpdate - Tail duplicate the block and cleanup.
bool
TailDuplicatePass::TailDuplicateAndUpdate(MachineBasicBlock *MBB,
bool IsSimple,
MachineFunction &MF) {
// Save the successors list.
SmallSetVector<MachineBasicBlock*, 8> Succs(MBB->succ_begin(),
MBB->succ_end());
SmallVector<MachineBasicBlock*, 8> TDBBs;
SmallVector<MachineInstr*, 16> Copies;
if (!TailDuplicate(MBB, MF, TDBBs, Copies))
continue;
if (!TailDuplicate(MBB, IsSimple, MF, TDBBs, Copies))
return false;
++NumTails;
SmallVector<MachineInstr*, 8> NewPHIs;
MachineSSAUpdater SSAUpdate(MF, &NewPHIs);
// TailBB's immediate successors are now successors of those predecessors
// which duplicated TailBB. Add the predecessors as sources to the PHI
// instructions.
@ -222,7 +216,6 @@ bool TailDuplicatePass::TailDuplicateBlocks(MachineFunction &MF) {
// Update SSA form.
if (!SSAUpdateVRs.empty()) {
NewPHIs.clear();
for (unsigned i = 0, e = SSAUpdateVRs.size(); i != e; ++i) {
unsigned VReg = SSAUpdateVRs[i];
SSAUpdate.Initialize(VReg);
@ -285,14 +278,39 @@ bool TailDuplicatePass::TailDuplicateBlocks(MachineFunction &MF) {
}
}
if (PreRegAlloc && TailDupVerify)
VerifyPHIs(MF, false);
MadeChange = true;
if (NewPHIs.size())
NumAddedPHIs += NewPHIs.size();
return true;
}
/// TailDuplicateBlocks - Look for small blocks that are unconditionally
/// branched to and do not fall through. Tail-duplicate their instructions
/// into their predecessors to eliminate (dynamic) branches.
bool TailDuplicatePass::TailDuplicateBlocks(MachineFunction &MF) {
bool MadeChange = false;
if (PreRegAlloc && TailDupVerify) {
DEBUG(dbgs() << "\n*** Before tail-duplicating\n");
VerifyPHIs(MF, true);
}
for (MachineFunction::iterator I = ++MF.begin(), E = MF.end(); I != E; ) {
MachineBasicBlock *MBB = I++;
if (NumTails == TailDupLimit)
break;
bool IsSimple = isSimpleBB(MBB);
if (!shouldTailDuplicate(MF, IsSimple, *MBB))
continue;
MadeChange |= TailDuplicateAndUpdate(MBB, IsSimple, MF);
}
if (PreRegAlloc && TailDupVerify)
VerifyPHIs(MF, false);
return MadeChange;
}
@ -532,14 +550,12 @@ TailDuplicatePass::shouldTailDuplicate(const MachineFunction &MF,
// to allow undoing the effects of tail merging and other optimizations
// that rearrange the predecessors of the indirect branch.
bool hasIndirectBR = false;
if (PreRegAlloc && !TailBB.empty()) {
const MCInstrDesc &MCID = TailBB.back().getDesc();
if (MCID.isIndirectBranch()) {
bool HasIndirectbr = false;
if (!TailBB.empty())
HasIndirectbr = TailBB.back().getDesc().isIndirectBranch();
if (HasIndirectbr && PreRegAlloc)
MaxDuplicateCount = 20;
hasIndirectBR = true;
}
}
// Check the instructions in the block to determine whether tail-duplication
// is invalid or unlikely to be profitable.
@ -569,7 +585,7 @@ TailDuplicatePass::shouldTailDuplicate(const MachineFunction &MF,
return false;
}
if (hasIndirectBR)
if (HasIndirectbr && PreRegAlloc)
return true;
if (IsSimple)
@ -711,14 +727,11 @@ TailDuplicatePass::duplicateSimpleBB(MachineBasicBlock *TailBB,
/// TailDuplicate - If it is profitable, duplicate TailBB's contents in each
/// of its predecessors.
bool
TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB,
bool IsSimple,
MachineFunction &MF,
SmallVector<MachineBasicBlock*, 8> &TDBBs,
SmallVector<MachineInstr*, 16> &Copies) {
bool IsSimple = isSimpleBB(TailBB);
if (!shouldTailDuplicate(MF, IsSimple, *TailBB))
return false;
DEBUG(dbgs() << "\n*** Tail-duplicating BB#" << TailBB->getNumber() << '\n');
DenseSet<unsigned> UsedByPhi;