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Move more logic to shouldTailDuplicate and only duplicate regular bb before

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register allocation if it has a indirectbr or if we can duplicate it to
every predecessor.

This fixes the SingleSource/Benchmarks/Shootout-C++/matrix.cpp regression but
keeps the previous improvements to sunspider.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133682 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola 2011-06-23 03:41:29 +00:00
parent 2fa82bc3da
commit 9dbbd87938
1 changed files with 45 additions and 21 deletions
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66
lib/CodeGen/TailDuplication.cpp
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@ -95,10 +95,10 @@ namespace {
SmallSetVector<MachineBasicBlock*, 8> &Succs);
bool TailDuplicateBlocks(MachineFunction &MF);
bool shouldTailDuplicate(const MachineFunction &MF,
MachineBasicBlock &TailBB);
bool IsSimple, MachineBasicBlock &TailBB);
bool isSimpleBB(MachineBasicBlock *TailBB);
bool canCompletelyDuplicateSimpleBB(MachineBasicBlock &BB);
bool duplicateSimpleBB(MachineBasicBlock *TailBB,
bool canCompletelyDuplicateBB(MachineBasicBlock &BB, bool IsSimple);
void duplicateSimpleBB(MachineBasicBlock *TailBB,
SmallVector<MachineBasicBlock*, 8> &TDBBs,
const DenseSet<unsigned> &RegsUsedByPhi,
SmallVector<MachineInstr*, 16> &Copies);
@ -501,6 +501,7 @@ TailDuplicatePass::UpdateSuccessorsPHIs(MachineBasicBlock *FromBB, bool isDead,
/// shouldTailDuplicate - Determine if it is profitable to duplicate this block.
bool
TailDuplicatePass::shouldTailDuplicate(const MachineFunction &MF,
bool IsSimple,
MachineBasicBlock &TailBB) {
// Only duplicate blocks that end with unconditional branches.
if (TailBB.canFallThrough())
@ -526,10 +527,13 @@ 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 TargetInstrDesc &TID = TailBB.back().getDesc();
if (TID.isIndirectBranch())
if (TID.isIndirectBranch()) {
MaxDuplicateCount = 20;
hasIndirectBR = true;
}
}
// Check the instructions in the block to determine whether tail-duplication
@ -560,7 +564,16 @@ TailDuplicatePass::shouldTailDuplicate(const MachineFunction &MF,
return false;
}
return true;
if (hasIndirectBR)
return true;
if (IsSimple)
return canCompletelyDuplicateBB(TailBB, IsSimple);
if (!PreRegAlloc)
return true;
return canCompletelyDuplicateBB(TailBB, IsSimple);
}
/// isSimpleBB - True if this BB has only one unconditional jump.
@ -568,6 +581,8 @@ bool
TailDuplicatePass::isSimpleBB(MachineBasicBlock *TailBB) {
if (TailBB->succ_size() != 1)
return false;
if (TailBB->pred_empty())
return false;
MachineBasicBlock::iterator I = TailBB->begin();
MachineBasicBlock::iterator E = TailBB->end();
while (I != E && I->isDebugValue())
@ -591,33 +606,40 @@ bothUsedInPHI(const MachineBasicBlock &A,
}
bool
TailDuplicatePass::canCompletelyDuplicateSimpleBB(MachineBasicBlock &BB) {
TailDuplicatePass::canCompletelyDuplicateBB(MachineBasicBlock &BB,
bool isSimple) {
SmallPtrSet<MachineBasicBlock*, 8> Succs(BB.succ_begin(), BB.succ_end());
for (MachineBasicBlock::pred_iterator PI = BB.pred_begin(),
PE = BB.pred_end(); PI != PE; ++PI) {
MachineBasicBlock *PredBB = *PI;
if (PredBB->getLandingPadSuccessor())
return false;
if (bothUsedInPHI(*PredBB, Succs))
return false;
if (isSimple) {
if (PredBB->getLandingPadSuccessor())
return false;
if (bothUsedInPHI(*PredBB, Succs))
return false;
} else {
if (PredBB->succ_size() > 1)
return false;
}
MachineBasicBlock *PredTBB = NULL, *PredFBB = NULL;
SmallVector<MachineOperand, 4> PredCond;
if (TII->AnalyzeBranch(*PredBB, PredTBB, PredFBB, PredCond, true))
return false;
if (!isSimple && !PredCond.empty())
return false;
}
return true;
}
bool
void
TailDuplicatePass::duplicateSimpleBB(MachineBasicBlock *TailBB,
SmallVector<MachineBasicBlock*, 8> &TDBBs,
const DenseSet<unsigned> &UsedByPhi,
SmallVector<MachineInstr*, 16> &Copies) {
if (!canCompletelyDuplicateSimpleBB(*TailBB))
return false;
bool Changed = false;
SmallVector<MachineBasicBlock*, 8> Preds(TailBB->pred_begin(),
TailBB->pred_end());
for (SmallSetVector<MachineBasicBlock *, 8>::iterator PI = Preds.begin(),
@ -692,10 +714,7 @@ TailDuplicatePass::duplicateSimpleBB(MachineBasicBlock *TailBB,
PredBB->addSuccessor(NewTarget);
TDBBs.push_back(PredBB);
Changed = true;
}
return Changed;
}
/// TailDuplicate - If it is profitable, duplicate TailBB's contents in each
@ -704,7 +723,9 @@ bool
TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
SmallVector<MachineBasicBlock*, 8> &TDBBs,
SmallVector<MachineInstr*, 16> &Copies) {
if (!shouldTailDuplicate(MF, *TailBB))
bool IsSimple = isSimpleBB(TailBB);
if (!shouldTailDuplicate(MF, IsSimple, *TailBB))
return false;
DEBUG(dbgs() << "\n*** Tail-duplicating BB#" << TailBB->getNumber() << '\n');
@ -712,8 +733,11 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
DenseSet<unsigned> UsedByPhi;
getRegsUsedByPHIs(*TailBB, &UsedByPhi);
if (isSimpleBB(TailBB))
return duplicateSimpleBB(TailBB, TDBBs, UsedByPhi, Copies);
if (IsSimple) {
duplicateSimpleBB(TailBB, TDBBs, UsedByPhi, Copies);
return true;
}
// Iterate through all the unique predecessors and tail-duplicate this
// block into them, if possible. Copying the list ahead of time also