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[MBP] Added some more debug messages and some clean ups /NFC 

Differential Revision: https://reviews.llvm.org/D22669

llvm-svn: 276849
This commit is contained in:
Sjoerd Meijer 2016-07-27 08:49:23 +00:00
parent d196fa524f
commit 5e11a18f5a
1 changed files with 31 additions and 11 deletions
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42
llvm/lib/CodeGen/MachineBlockPlacement.cpp
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@ -78,10 +78,14 @@ static cl::opt<unsigned> ExitBlockBias(
"over the original exit to be considered the new exit."), "over the original exit to be considered the new exit."),
cl::init(0), cl::Hidden); cl::init(0), cl::Hidden);
// Definition:
// - Outlining: placement of a basic block outside the chain or hot path.
static cl::opt<bool> OutlineOptionalBranches( static cl::opt<bool> OutlineOptionalBranches(
"outline-optional-branches", "outline-optional-branches",
cl::desc("Put completely optional branches, i.e. branches with a common " cl::desc("Outlining optional branches will place blocks that are optional "
"post dominator, out of line."), "branches, i.e. branches with a common post dominator, outside "
"the hot path or chain"),
cl::init(false), cl::Hidden); cl::init(false), cl::Hidden);
static cl::opt<unsigned> OutlineOptionalThreshold( static cl::opt<unsigned> OutlineOptionalThreshold(
@ -632,8 +636,10 @@ bool MachineBlockPlacement::hasBetterLayoutPredecessor(
// Forward checking. For case 2, SuccProb will be 1. // Forward checking. For case 2, SuccProb will be 1.
if (SuccProb < HotProb) { if (SuccProb < HotProb) {
DEBUG(dbgs() << " " << getBlockName(Succ) << " -> " << SuccProb DEBUG(dbgs() << " Not a candidate: " << getBlockName(Succ) << " "
<< " (prob) (CFG conflict)\n"); << "Respecting topological ordering because "
<< "probability is less than prob treshold: "
<< SuccProb << "\n");
return true; return true;
} }
@ -669,7 +675,7 @@ bool MachineBlockPlacement::hasBetterLayoutPredecessor(
} }
if (BadCFGConflict) { if (BadCFGConflict) {
DEBUG(dbgs() << " " << getBlockName(Succ) << " -> " << SuccProb DEBUG(dbgs() << " Not a candidate: " << getBlockName(Succ) << " -> " << SuccProb
<< " (prob) (non-cold CFG conflict)\n"); << " (prob) (non-cold CFG conflict)\n");
return true; return true;
} }
@ -699,7 +705,7 @@ MachineBlockPlacement::selectBestSuccessor(MachineBasicBlock *BB,
auto AdjustedSumProb = auto AdjustedSumProb =
collectViableSuccessors(BB, Chain, BlockFilter, Successors); collectViableSuccessors(BB, Chain, BlockFilter, Successors);
DEBUG(dbgs() << "Attempting merge from: " << getBlockName(BB) << "\n"); DEBUG(dbgs() << "Selecting best successor for: " << getBlockName(BB) << "\n");
for (MachineBasicBlock *Succ : Successors) { for (MachineBasicBlock *Succ : Successors) {
auto RealSuccProb = MBPI->getEdgeProbability(BB, Succ); auto RealSuccProb = MBPI->getEdgeProbability(BB, Succ);
BranchProbability SuccProb = BranchProbability SuccProb =
@ -718,15 +724,23 @@ MachineBlockPlacement::selectBestSuccessor(MachineBasicBlock *BB,
continue; continue;
DEBUG( DEBUG(
dbgs() << " " << getBlockName(Succ) << " -> " << SuccProb dbgs() << " Candidate: " << getBlockName(Succ) << ", probability: "
<< " (prob)" << SuccProb
<< (SuccChain.UnscheduledPredecessors != 0 ? " (CFG break)" : "") << (SuccChain.UnscheduledPredecessors != 0 ? " (CFG break)" : "")
<< "\n"); << "\n");
if (BestSucc && BestProb >= SuccProb)
if (BestSucc && BestProb >= SuccProb) {
DEBUG(dbgs() << " Not the best candidate, continuing\n");
continue; continue;
}
DEBUG(dbgs() << " Setting it as best candidate\n");
BestSucc = Succ; BestSucc = Succ;
BestProb = SuccProb; BestProb = SuccProb;
} }
if (BestSucc)
DEBUG(dbgs() << " Selected: " << getBlockName(BestSucc) << "\n");
return BestSucc; return BestSucc;
} }
@ -937,7 +951,7 @@ MachineBlockPlacement::findBestLoopTop(MachineLoop &L,
for (MachineBasicBlock *Pred : L.getHeader()->predecessors()) { for (MachineBasicBlock *Pred : L.getHeader()->predecessors()) {
if (!LoopBlockSet.count(Pred)) if (!LoopBlockSet.count(Pred))
continue; continue;
DEBUG(dbgs() << " header pred: " << getBlockName(Pred) << ", " DEBUG(dbgs() << " header pred: " << getBlockName(Pred) << ", has "
<< Pred->succ_size() << " successors, "; << Pred->succ_size() << " successors, ";
MBFI->printBlockFreq(dbgs(), Pred) << " freq\n"); MBFI->printBlockFreq(dbgs(), Pred) << " freq\n");
if (Pred->succ_size() > 1) if (Pred->succ_size() > 1)
@ -1066,8 +1080,14 @@ MachineBlockPlacement::findBestLoopExit(MachineLoop &L,
} }
// Without a candidate exiting block or with only a single block in the // Without a candidate exiting block or with only a single block in the
// loop, just use the loop header to layout the loop. // loop, just use the loop header to layout the loop.
if (!ExitingBB || L.getNumBlocks() == 1) if (!ExitingBB) {
DEBUG(dbgs() << " No other candidate exit blocks, using loop header\n");
return nullptr; return nullptr;
}
if (L.getNumBlocks() == 1) {
DEBUG(dbgs() << " Loop has 1 block, using loop header as exit\n");
return nullptr;
}
// Also, if we have exit blocks which lead to outer loops but didn't select // Also, if we have exit blocks which lead to outer loops but didn't select
// one of them as the exiting block we are rotating toward, disable loop // one of them as the exiting block we are rotating toward, disable loop