[llvm] r276849 - [MBP] Added some more debug messages and some clean ups /NFC
Sjoerd Meijer via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 27 01:49:24 PDT 2016
Author: sjoerdmeijer
Date: Wed Jul 27 03:49:23 2016
New Revision: 276849
URL: http://llvm.org/viewvc/llvm-project?rev=276849&view=rev
Log:
[MBP] Added some more debug messages and some clean ups /NFC
Differential Revision: https://reviews.llvm.org/D22669
Modified:
llvm/trunk/lib/CodeGen/MachineBlockPlacement.cpp
Modified: llvm/trunk/lib/CodeGen/MachineBlockPlacement.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineBlockPlacement.cpp?rev=276849&r1=276848&r2=276849&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineBlockPlacement.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineBlockPlacement.cpp Wed Jul 27 03:49:23 2016
@@ -78,10 +78,14 @@ static cl::opt<unsigned> ExitBlockBias(
"over the original exit to be considered the new exit."),
cl::init(0), cl::Hidden);
+// Definition:
+// - Outlining: placement of a basic block outside the chain or hot path.
+
static cl::opt<bool> OutlineOptionalBranches(
"outline-optional-branches",
- cl::desc("Put completely optional branches, i.e. branches with a common "
- "post dominator, out of line."),
+ cl::desc("Outlining optional branches will place blocks that are optional "
+ "branches, i.e. branches with a common post dominator, outside "
+ "the hot path or chain"),
cl::init(false), cl::Hidden);
static cl::opt<unsigned> OutlineOptionalThreshold(
@@ -632,8 +636,10 @@ bool MachineBlockPlacement::hasBetterLay
// Forward checking. For case 2, SuccProb will be 1.
if (SuccProb < HotProb) {
- DEBUG(dbgs() << " " << getBlockName(Succ) << " -> " << SuccProb
- << " (prob) (CFG conflict)\n");
+ DEBUG(dbgs() << " Not a candidate: " << getBlockName(Succ) << " "
+ << "Respecting topological ordering because "
+ << "probability is less than prob treshold: "
+ << SuccProb << "\n");
return true;
}
@@ -669,7 +675,7 @@ bool MachineBlockPlacement::hasBetterLay
}
if (BadCFGConflict) {
- DEBUG(dbgs() << " " << getBlockName(Succ) << " -> " << SuccProb
+ DEBUG(dbgs() << " Not a candidate: " << getBlockName(Succ) << " -> " << SuccProb
<< " (prob) (non-cold CFG conflict)\n");
return true;
}
@@ -699,7 +705,7 @@ MachineBlockPlacement::selectBestSuccess
auto AdjustedSumProb =
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) {
auto RealSuccProb = MBPI->getEdgeProbability(BB, Succ);
BranchProbability SuccProb =
@@ -718,15 +724,23 @@ MachineBlockPlacement::selectBestSuccess
continue;
DEBUG(
- dbgs() << " " << getBlockName(Succ) << " -> " << SuccProb
- << " (prob)"
+ dbgs() << " Candidate: " << getBlockName(Succ) << ", probability: "
+ << SuccProb
<< (SuccChain.UnscheduledPredecessors != 0 ? " (CFG break)" : "")
<< "\n");
- if (BestSucc && BestProb >= SuccProb)
+
+ if (BestSucc && BestProb >= SuccProb) {
+ DEBUG(dbgs() << " Not the best candidate, continuing\n");
continue;
+ }
+
+ DEBUG(dbgs() << " Setting it as best candidate\n");
BestSucc = Succ;
BestProb = SuccProb;
}
+ if (BestSucc)
+ DEBUG(dbgs() << " Selected: " << getBlockName(BestSucc) << "\n");
+
return BestSucc;
}
@@ -937,7 +951,7 @@ MachineBlockPlacement::findBestLoopTop(M
for (MachineBasicBlock *Pred : L.getHeader()->predecessors()) {
if (!LoopBlockSet.count(Pred))
continue;
- DEBUG(dbgs() << " header pred: " << getBlockName(Pred) << ", "
+ DEBUG(dbgs() << " header pred: " << getBlockName(Pred) << ", has "
<< Pred->succ_size() << " successors, ";
MBFI->printBlockFreq(dbgs(), Pred) << " freq\n");
if (Pred->succ_size() > 1)
@@ -1066,8 +1080,14 @@ MachineBlockPlacement::findBestLoopExit(
}
// Without a candidate exiting block or with only a single block in the
// 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;
+ }
+ 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
// one of them as the exiting block we are rotating toward, disable loop
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