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- Change a few operator[] to lookup which is cheaper. 

- Add some constantness.

llvm-svn: 147090
This commit is contained in:
Jakub Staszak 2011-12-21 20:18:54 +00:00
parent e49fbd0755
commit df5133455f
1 changed files with 43 additions and 45 deletions
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88
llvm/lib/CodeGen/MachineBlockPlacement.cpp
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@ -116,7 +116,7 @@ public:
/// a contiguous sequence of basic blocks, updating the edge list, and
/// updating the block -> chain mapping. It does not free or tear down the
/// old chain, but the old chain's block list is no longer valid.
void merge(MachineBasicBlock *BB, BlockChain *Chain) {
void merge(MachineBasicBlock *BB, const BlockChain *Chain) {
assert(BB);
assert(!Blocks.empty());
@ -185,28 +185,27 @@ class MachineBlockPlacement : public MachineFunctionPass {
/// between basic blocks.
DenseMap<MachineBasicBlock *, BlockChain *> BlockToChain;
void markChainSuccessors(BlockChain &Chain,
MachineBasicBlock *LoopHeaderBB,
void markChainSuccessors(const BlockChain &Chain,
const MachineBasicBlock *LoopHeaderBB,
SmallVectorImpl<MachineBasicBlock *> &BlockWorkList,
const BlockFilterSet *BlockFilter = 0);
MachineBasicBlock *selectBestSuccessor(MachineBasicBlock *BB,
BlockChain &Chain,
const BlockFilterSet *BlockFilter);
const BlockFilterSet *BlockFilter = 0) const;
MachineBasicBlock *selectBestSuccessor(const MachineBasicBlock *BB,
const BlockChain &Chain, const BlockFilterSet *BlockFilter) const;
MachineBasicBlock *selectBestCandidateBlock(
BlockChain &Chain, SmallVectorImpl<MachineBasicBlock *> &WorkList,
const BlockFilterSet *BlockFilter);
const BlockChain &Chain, SmallVectorImpl<MachineBasicBlock *> &WorkList,
const BlockFilterSet *BlockFilter) const;
MachineBasicBlock *getFirstUnplacedBlock(
MachineFunction &F,
const BlockChain &PlacedChain,
MachineFunction::iterator &PrevUnplacedBlockIt,
const BlockFilterSet *BlockFilter);
const BlockFilterSet *BlockFilter) const;
void buildChain(MachineBasicBlock *BB, BlockChain &Chain,
SmallVectorImpl<MachineBasicBlock *> &BlockWorkList,
const BlockFilterSet *BlockFilter = 0);
const BlockFilterSet *BlockFilter = 0) const;
MachineBasicBlock *findBestLoopTop(MachineFunction &F,
MachineLoop &L,
const BlockFilterSet &LoopBlockSet);
void buildLoopChains(MachineFunction &F, MachineLoop &L);
const BlockFilterSet &LoopBlockSet) const;
void buildLoopChains(MachineFunction &F, MachineLoop &L) const;
void buildCFGChains(MachineFunction &F);
void AlignLoops(MachineFunction &F);
@ -246,7 +245,7 @@ FunctionPass *llvm::createMachineBlockPlacementPass() {
/// \brief Helper to print the name of a MBB.
///
/// Only used by debug logging.
static std::string getBlockName(MachineBasicBlock *BB) {
static std::string getBlockName(const MachineBasicBlock *BB) {
std::string Result;
raw_string_ostream OS(Result);
OS << "BB#" << BB->getNumber()
@ -258,7 +257,7 @@ static std::string getBlockName(MachineBasicBlock *BB) {
/// \brief Helper to print the number of a MBB.
///
/// Only used by debug logging.
static std::string getBlockNum(MachineBasicBlock *BB) {
static std::string getBlockNum(const MachineBasicBlock *BB) {
std::string Result;
raw_string_ostream OS(Result);
OS << "BB#" << BB->getNumber();
@ -274,10 +273,10 @@ static std::string getBlockNum(MachineBasicBlock *BB) {
/// having one fewer active predecessor. It also adds any successors of this
/// chain which reach the zero-predecessor state to the worklist passed in.
void MachineBlockPlacement::markChainSuccessors(
BlockChain &Chain,
MachineBasicBlock *LoopHeaderBB,
const BlockChain &Chain,
const MachineBasicBlock *LoopHeaderBB,
SmallVectorImpl<MachineBasicBlock *> &BlockWorkList,
const BlockFilterSet *BlockFilter) {
const BlockFilterSet *BlockFilter) const {
// Walk all the blocks in this chain, marking their successors as having
// a predecessor placed.
for (BlockChain::iterator CBI = Chain.begin(), CBE = Chain.end();
@ -291,7 +290,7 @@ void MachineBlockPlacement::markChainSuccessors(
SI != SE; ++SI) {
if (BlockFilter && !BlockFilter->count(*SI))
continue;
BlockChain &SuccChain = *BlockToChain[*SI];
BlockChain &SuccChain = *BlockToChain.lookup(*SI);
// Disregard edges within a fixed chain, or edges to the loop header.
if (&Chain == &SuccChain || *SI == LoopHeaderBB)
continue;
@ -314,8 +313,8 @@ void MachineBlockPlacement::markChainSuccessors(
///
/// \returns The best successor block found, or null if none are viable.
MachineBasicBlock *MachineBlockPlacement::selectBestSuccessor(
MachineBasicBlock *BB, BlockChain &Chain,
const BlockFilterSet *BlockFilter) {
const MachineBasicBlock *BB, const BlockChain &Chain,
const BlockFilterSet *BlockFilter) const {
const BranchProbability HotProb(4, 5); // 80%
MachineBasicBlock *BestSucc = 0;
@ -329,12 +328,11 @@ MachineBasicBlock *MachineBlockPlacement::selectBestSuccessor(
uint32_t WeightScale = 0;
uint32_t SumWeight = MBPI->getSumForBlock(BB, WeightScale);
DEBUG(dbgs() << "Attempting merge from: " << getBlockName(BB) << "\n");
for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
SE = BB->succ_end();
SI != SE; ++SI) {
for (MachineBasicBlock::const_succ_iterator SI = BB->succ_begin(),
SE = BB->succ_end(); SI != SE; ++SI) {
if (BlockFilter && !BlockFilter->count(*SI))
continue;
BlockChain &SuccChain = *BlockToChain[*SI];
const BlockChain &SuccChain = *BlockToChain.lookup(*SI);
if (&SuccChain == &Chain) {
DEBUG(dbgs() << " " << getBlockName(*SI) << " -> Already merged!\n");
continue;
@ -364,7 +362,7 @@ MachineBasicBlock *MachineBlockPlacement::selectBestSuccessor(
PE = (*SI)->pred_end();
PI != PE; ++PI) {
if (*PI == *SI || (BlockFilter && !BlockFilter->count(*PI)) ||
BlockToChain[*PI] == &Chain)
BlockToChain.lookup(*PI) == &Chain)
continue;
BlockFrequency PredEdgeFreq
= MBFI->getBlockFreq(*PI) * MBPI->getEdgeProbability(*PI, *SI);
@ -420,8 +418,8 @@ public:
///
/// \returns The best block found, or null if none are viable.
MachineBasicBlock *MachineBlockPlacement::selectBestCandidateBlock(
BlockChain &Chain, SmallVectorImpl<MachineBasicBlock *> &WorkList,
const BlockFilterSet *BlockFilter) {
const BlockChain &Chain, SmallVectorImpl<MachineBasicBlock *> &WorkList,
const BlockFilterSet *BlockFilter) const {
// Once we need to walk the worklist looking for a candidate, cleanup the
// worklist of already placed entries.
// FIXME: If this shows up on profiles, it could be folded (at the cost of
@ -436,7 +434,7 @@ MachineBasicBlock *MachineBlockPlacement::selectBestCandidateBlock(
WBE = WorkList.end();
WBI != WBE; ++WBI) {
assert(!BlockFilter || BlockFilter->count(*WBI));
BlockChain &SuccChain = *BlockToChain[*WBI];
const BlockChain &SuccChain = *BlockToChain.lookup(*WBI);
if (&SuccChain == &Chain) {
DEBUG(dbgs() << " " << getBlockName(*WBI)
<< " -> Already merged!\n");
@ -465,17 +463,17 @@ MachineBasicBlock *MachineBlockPlacement::selectBestCandidateBlock(
MachineBasicBlock *MachineBlockPlacement::getFirstUnplacedBlock(
MachineFunction &F, const BlockChain &PlacedChain,
MachineFunction::iterator &PrevUnplacedBlockIt,
const BlockFilterSet *BlockFilter) {
const BlockFilterSet *BlockFilter) const {
for (MachineFunction::iterator I = PrevUnplacedBlockIt, E = F.end(); I != E;
++I) {
if (BlockFilter && !BlockFilter->count(I))
continue;
if (BlockToChain[I] != &PlacedChain) {
if (BlockToChain.lookup(I) != &PlacedChain) {
PrevUnplacedBlockIt = I;
// Now select the head of the chain to which the unplaced block belongs
// as the block to place. This will force the entire chain to be placed,
// and satisfies the requirements of merging chains.
return *BlockToChain[I]->begin();
return *BlockToChain.lookup(I)->begin();
}
}
return 0;
@ -485,9 +483,9 @@ void MachineBlockPlacement::buildChain(
MachineBasicBlock *BB,
BlockChain &Chain,
SmallVectorImpl<MachineBasicBlock *> &BlockWorkList,
const BlockFilterSet *BlockFilter) {
const BlockFilterSet *BlockFilter) const {
assert(BB);
assert(BlockToChain[BB] == &Chain);
assert(BlockToChain.lookup(BB) == &Chain);
MachineFunction &F = *BB->getParent();
MachineFunction::iterator PrevUnplacedBlockIt = F.begin();
@ -496,7 +494,7 @@ void MachineBlockPlacement::buildChain(
BB = *llvm::prior(Chain.end());
for (;;) {
assert(BB);
assert(BlockToChain[BB] == &Chain);
assert(BlockToChain.lookup(BB) == &Chain);
assert(*llvm::prior(Chain.end()) == BB);
MachineBasicBlock *BestSucc = 0;
@ -521,7 +519,7 @@ void MachineBlockPlacement::buildChain(
}
// Place this block, updating the datastructures to reflect its placement.
BlockChain &SuccChain = *BlockToChain[BestSucc];
BlockChain &SuccChain = *BlockToChain.lookup(BestSucc);
// Zero out LoopPredecessors for the successor we're about to merge in case
// we selected a successor that didn't fit naturally into the CFG.
SuccChain.LoopPredecessors = 0;
@ -544,7 +542,7 @@ void MachineBlockPlacement::buildChain(
MachineBasicBlock *
MachineBlockPlacement::findBestLoopTop(MachineFunction &F,
MachineLoop &L,
const BlockFilterSet &LoopBlockSet) {
const BlockFilterSet &LoopBlockSet) const {
BlockFrequency BestExitEdgeFreq;
MachineBasicBlock *ExitingBB = 0;
MachineBasicBlock *LoopingBB = 0;
@ -558,7 +556,7 @@ MachineBlockPlacement::findBestLoopTop(MachineFunction &F,
for (MachineLoop::block_iterator I = L.block_begin(),
E = L.block_end();
I != E; ++I) {
BlockChain &Chain = *BlockToChain[*I];
const BlockChain &Chain = *BlockToChain.lookup(*I);
// Ensure that this block is at the end of a chain; otherwise it could be
// mid-way through an inner loop or a successor of an analyzable branch.
if (*I != *llvm::prior(Chain.end()))
@ -588,7 +586,7 @@ MachineBlockPlacement::findBestLoopTop(MachineFunction &F,
continue;
if (*SI == *I)
continue;
BlockChain &SuccChain = *BlockToChain[*SI];
const BlockChain &SuccChain = *BlockToChain.lookup(*SI);
// Don't split chains, either this chain or the successor's chain.
if (&Chain == &SuccChain || *SI != *SuccChain.begin()) {
DEBUG(dbgs() << " " << (LoopBlockSet.count(*SI) ? "looping: "
@ -665,7 +663,7 @@ MachineBlockPlacement::findBestLoopTop(MachineFunction &F,
/// both preserves the topological structure and minimizes taken conditional
/// branches.
void MachineBlockPlacement::buildLoopChains(MachineFunction &F,
MachineLoop &L) {
MachineLoop &L) const {
// First recurse through any nested loops, building chains for those inner
// loops.
for (MachineLoop::iterator LI = L.begin(), LE = L.end(); LI != LE; ++LI)
@ -675,29 +673,29 @@ void MachineBlockPlacement::buildLoopChains(MachineFunction &F,
BlockFilterSet LoopBlockSet(L.block_begin(), L.block_end());
MachineBasicBlock *LayoutTop = findBestLoopTop(F, L, LoopBlockSet);
BlockChain &LoopChain = *BlockToChain[LayoutTop];
BlockChain &LoopChain = *BlockToChain.lookup(LayoutTop);
// FIXME: This is a really lame way of walking the chains in the loop: we
// walk the blocks, and use a set to prevent visiting a particular chain
// twice.
SmallPtrSet<BlockChain *, 4> UpdatedPreds;
SmallPtrSet<const BlockChain *, 4> UpdatedPreds;
assert(LoopChain.LoopPredecessors == 0);
UpdatedPreds.insert(&LoopChain);
for (MachineLoop::block_iterator BI = L.block_begin(),
BE = L.block_end();
BI != BE; ++BI) {
BlockChain &Chain = *BlockToChain[*BI];
BlockChain &Chain = *BlockToChain.lookup(*BI);
if (!UpdatedPreds.insert(&Chain))
continue;
assert(Chain.LoopPredecessors == 0);
for (BlockChain::iterator BCI = Chain.begin(), BCE = Chain.end();
BCI != BCE; ++BCI) {
assert(BlockToChain[*BCI] == &Chain);
assert(BlockToChain.lookup(*BCI) == &Chain);
for (MachineBasicBlock::pred_iterator PI = (*BCI)->pred_begin(),
PE = (*BCI)->pred_end();
PI != PE; ++PI) {
if (BlockToChain[*PI] == &Chain || !LoopBlockSet.count(*PI))
if (BlockToChain.lookup(*PI) == &Chain || !LoopBlockSet.count(*PI))
continue;
++Chain.LoopPredecessors;
}