[llvm-commits] [llvm] r142783 - in /llvm/trunk: include/llvm/Analysis/BranchProbabilityInfo.h lib/Analysis/BranchProbabilityInfo.cpp
Chandler Carruth
chandlerc at gmail.com
Sun Oct 23 18:40:45 PDT 2011
Author: chandlerc
Date: Sun Oct 23 20:40:45 2011
New Revision: 142783
URL: http://llvm.org/viewvc/llvm-project?rev=142783&view=rev
Log:
Simplify the design of BranchProbabilityInfo by collapsing it into
a single class. Previously it was split between two classes, one
internal and one external. The concern seemed to center around exposing
the weights used, but those can remain confined to the implementation
file.
Having a single class to maintain the state and analyses in use will
also simplify several of the enhancements I want to make to our static
heuristics.
Modified:
llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h
llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
Modified: llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h?rev=142783&r1=142782&r2=142783&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h (original)
+++ llvm/trunk/include/llvm/Analysis/BranchProbabilityInfo.h Sun Oct 23 20:40:45 2011
@@ -20,29 +20,10 @@
#include "llvm/Support/BranchProbability.h"
namespace llvm {
-
+class LoopInfo;
class raw_ostream;
class BranchProbabilityInfo : public FunctionPass {
-
- // Default weight value. Used when we don't have information about the edge.
- // TODO: DEFAULT_WEIGHT makes sense during static predication, when none of
- // the successors have a weight yet. But it doesn't make sense when providing
- // weight to an edge that may have siblings with non-zero weights. This can
- // be handled various ways, but it's probably fine for an edge with unknown
- // weight to just "inherit" the non-zero weight of an adjacent successor.
- static const uint32_t DEFAULT_WEIGHT = 16;
-
- typedef std::pair<const BasicBlock *, const BasicBlock *> Edge;
-
- DenseMap<Edge, uint32_t> Weights;
-
- /// \brief Track the last function we run over for printing.
- Function *LastF;
-
- // Get sum of the block successors' weights.
- uint32_t getSumForBlock(const BasicBlock *BB) const;
-
public:
static char ID;
@@ -79,6 +60,35 @@
// has only one successor.
raw_ostream &printEdgeProbability(raw_ostream &OS, const BasicBlock *Src,
const BasicBlock *Dst) const;
+
+private:
+ typedef std::pair<const BasicBlock *, const BasicBlock *> Edge;
+
+ // Default weight value. Used when we don't have information about the edge.
+ // TODO: DEFAULT_WEIGHT makes sense during static predication, when none of
+ // the successors have a weight yet. But it doesn't make sense when providing
+ // weight to an edge that may have siblings with non-zero weights. This can
+ // be handled various ways, but it's probably fine for an edge with unknown
+ // weight to just "inherit" the non-zero weight of an adjacent successor.
+ static const uint32_t DEFAULT_WEIGHT = 16;
+
+ DenseMap<Edge, uint32_t> Weights;
+
+ /// \brief Handle to the LoopInfo analysis.
+ LoopInfo *LI;
+
+ /// \brief Track the last function we run over for printing.
+ Function *LastF;
+
+ /// \brief Get sum of the block successors' weights.
+ uint32_t getSumForBlock(const BasicBlock *BB) const;
+
+ bool calcMetadataWeights(BasicBlock *BB);
+ bool calcReturnHeuristics(BasicBlock *BB);
+ bool calcPointerHeuristics(BasicBlock *BB);
+ bool calcLoopBranchHeuristics(BasicBlock *BB);
+ bool calcZeroHeuristics(BasicBlock *BB);
+ bool calcFloatingPointHeuristics(BasicBlock *BB);
};
}
Modified: llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp?rev=142783&r1=142782&r2=142783&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp Sun Oct 23 20:40:45 2011
@@ -31,124 +31,83 @@
char BranchProbabilityInfo::ID = 0;
-namespace {
-// Please note that BranchProbabilityAnalysis is not a FunctionPass.
-// It is created by BranchProbabilityInfo (which is a FunctionPass), which
-// provides a clear interface. Thanks to that, all heuristics and other
-// private methods are hidden in the .cpp file.
-class BranchProbabilityAnalysis {
-
- typedef std::pair<const BasicBlock *, const BasicBlock *> Edge;
-
- BranchProbabilityInfo *BP;
-
- LoopInfo *LI;
-
-
- // Weights are for internal use only. They are used by heuristics to help to
- // estimate edges' probability. Example:
- //
- // Using "Loop Branch Heuristics" we predict weights of edges for the
- // block BB2.
- // ...
- // |
- // V
- // BB1<-+
- // | |
- // | | (Weight = 124)
- // V |
- // BB2--+
- // |
- // | (Weight = 4)
- // V
- // BB3
- //
- // Probability of the edge BB2->BB1 = 124 / (124 + 4) = 0.96875
- // Probability of the edge BB2->BB3 = 4 / (124 + 4) = 0.03125
-
- static const uint32_t LBH_TAKEN_WEIGHT = 124;
- static const uint32_t LBH_NONTAKEN_WEIGHT = 4;
-
- static const uint32_t RH_TAKEN_WEIGHT = 24;
- static const uint32_t RH_NONTAKEN_WEIGHT = 8;
-
- static const uint32_t PH_TAKEN_WEIGHT = 20;
- static const uint32_t PH_NONTAKEN_WEIGHT = 12;
-
- static const uint32_t ZH_TAKEN_WEIGHT = 20;
- static const uint32_t ZH_NONTAKEN_WEIGHT = 12;
-
- static const uint32_t FPH_TAKEN_WEIGHT = 20;
- static const uint32_t FPH_NONTAKEN_WEIGHT = 12;
-
- // Standard weight value. Used when none of the heuristics set weight for
- // the edge.
- static const uint32_t NORMAL_WEIGHT = 16;
-
- // Minimum weight of an edge. Please note, that weight is NEVER 0.
- static const uint32_t MIN_WEIGHT = 1;
-
- // Return TRUE if BB leads directly to a Return Instruction.
- static bool isReturningBlock(BasicBlock *BB) {
- SmallPtrSet<BasicBlock *, 8> Visited;
-
- while (true) {
- TerminatorInst *TI = BB->getTerminator();
- if (isa<ReturnInst>(TI))
- return true;
-
- if (TI->getNumSuccessors() > 1)
- break;
-
- // It is unreachable block which we can consider as a return instruction.
- if (TI->getNumSuccessors() == 0)
- return true;
-
- Visited.insert(BB);
- BB = TI->getSuccessor(0);
-
- // Stop if cycle is detected.
- if (Visited.count(BB))
- return false;
- }
-
- return false;
- }
-
- uint32_t getMaxWeightFor(BasicBlock *BB) const {
- return UINT32_MAX / BB->getTerminator()->getNumSuccessors();
- }
-
-public:
- BranchProbabilityAnalysis(BranchProbabilityInfo *BP, LoopInfo *LI)
- : BP(BP), LI(LI) {
- }
+// Weights are for internal use only. They are used by heuristics to help to
+// estimate edges' probability. Example:
+//
+// Using "Loop Branch Heuristics" we predict weights of edges for the
+// block BB2.
+// ...
+// |
+// V
+// BB1<-+
+// | |
+// | | (Weight = 124)
+// V |
+// BB2--+
+// |
+// | (Weight = 4)
+// V
+// BB3
+//
+// Probability of the edge BB2->BB1 = 124 / (124 + 4) = 0.96875
+// Probability of the edge BB2->BB3 = 4 / (124 + 4) = 0.03125
+static const uint32_t LBH_TAKEN_WEIGHT = 124;
+static const uint32_t LBH_NONTAKEN_WEIGHT = 4;
+
+static const uint32_t RH_TAKEN_WEIGHT = 24;
+static const uint32_t RH_NONTAKEN_WEIGHT = 8;
+
+static const uint32_t PH_TAKEN_WEIGHT = 20;
+static const uint32_t PH_NONTAKEN_WEIGHT = 12;
+
+static const uint32_t ZH_TAKEN_WEIGHT = 20;
+static const uint32_t ZH_NONTAKEN_WEIGHT = 12;
+
+static const uint32_t FPH_TAKEN_WEIGHT = 20;
+static const uint32_t FPH_NONTAKEN_WEIGHT = 12;
+
+// Standard weight value. Used when none of the heuristics set weight for
+// the edge.
+static const uint32_t NORMAL_WEIGHT = 16;
+
+// Minimum weight of an edge. Please note, that weight is NEVER 0.
+static const uint32_t MIN_WEIGHT = 1;
+
+// Return TRUE if BB leads directly to a Return Instruction.
+static bool isReturningBlock(BasicBlock *BB) {
+ SmallPtrSet<BasicBlock *, 8> Visited;
+
+ while (true) {
+ TerminatorInst *TI = BB->getTerminator();
+ if (isa<ReturnInst>(TI))
+ return true;
- // Metadata Weights
- bool calcMetadataWeights(BasicBlock *BB);
+ if (TI->getNumSuccessors() > 1)
+ break;
- // Return Heuristics
- bool calcReturnHeuristics(BasicBlock *BB);
+ // It is unreachable block which we can consider as a return instruction.
+ if (TI->getNumSuccessors() == 0)
+ return true;
- // Pointer Heuristics
- bool calcPointerHeuristics(BasicBlock *BB);
+ Visited.insert(BB);
+ BB = TI->getSuccessor(0);
- // Loop Branch Heuristics
- bool calcLoopBranchHeuristics(BasicBlock *BB);
+ // Stop if cycle is detected.
+ if (Visited.count(BB))
+ return false;
+ }
- // Zero Heuristics
- bool calcZeroHeuristics(BasicBlock *BB);
+ return false;
+}
- // Floating Point Heuristics
- bool calcFloatingPointHeuristics(BasicBlock *BB);
+static uint32_t getMaxWeightFor(BasicBlock *BB) {
+ return UINT32_MAX / BB->getTerminator()->getNumSuccessors();
+}
- bool runOnFunction(Function &F);
-};
-} // end anonymous namespace
// Propagate existing explicit probabilities from either profile data or
// 'expect' intrinsic processing.
-bool BranchProbabilityAnalysis::calcMetadataWeights(BasicBlock *BB) {
+bool BranchProbabilityInfo::calcMetadataWeights(BasicBlock *BB) {
TerminatorInst *TI = BB->getTerminator();
if (TI->getNumSuccessors() == 1)
return false;
@@ -179,14 +138,14 @@
}
assert(Weights.size() == TI->getNumSuccessors() && "Checked above");
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
- BP->setEdgeWeight(BB, TI->getSuccessor(i), Weights[i]);
+ setEdgeWeight(BB, TI->getSuccessor(i), Weights[i]);
return true;
}
// Calculate Edge Weights using "Return Heuristics". Predict a successor which
// leads directly to Return Instruction will not be taken.
-bool BranchProbabilityAnalysis::calcReturnHeuristics(BasicBlock *BB){
+bool BranchProbabilityInfo::calcReturnHeuristics(BasicBlock *BB){
if (BB->getTerminator()->getNumSuccessors() == 1)
return false;
@@ -208,7 +167,7 @@
for (SmallPtrSet<BasicBlock *, 4>::iterator I = StayEdges.begin(),
E = StayEdges.end(); I != E; ++I)
- BP->setEdgeWeight(BB, *I, stayWeight);
+ setEdgeWeight(BB, *I, stayWeight);
}
if (uint32_t numRetEdges = ReturningEdges.size()) {
@@ -217,7 +176,7 @@
retWeight = MIN_WEIGHT;
for (SmallPtrSet<BasicBlock *, 4>::iterator I = ReturningEdges.begin(),
E = ReturningEdges.end(); I != E; ++I) {
- BP->setEdgeWeight(BB, *I, retWeight);
+ setEdgeWeight(BB, *I, retWeight);
}
}
@@ -226,7 +185,7 @@
// Calculate Edge Weights using "Pointer Heuristics". Predict a comparsion
// between two pointer or pointer and NULL will fail.
-bool BranchProbabilityAnalysis::calcPointerHeuristics(BasicBlock *BB) {
+bool BranchProbabilityInfo::calcPointerHeuristics(BasicBlock *BB) {
BranchInst * BI = dyn_cast<BranchInst>(BB->getTerminator());
if (!BI || !BI->isConditional())
return false;
@@ -254,14 +213,14 @@
if (!isProb)
std::swap(Taken, NonTaken);
- BP->setEdgeWeight(BB, Taken, PH_TAKEN_WEIGHT);
- BP->setEdgeWeight(BB, NonTaken, PH_NONTAKEN_WEIGHT);
+ setEdgeWeight(BB, Taken, PH_TAKEN_WEIGHT);
+ setEdgeWeight(BB, NonTaken, PH_NONTAKEN_WEIGHT);
return true;
}
// Calculate Edge Weights using "Loop Branch Heuristics". Predict backedges
// as taken, exiting edges as not-taken.
-bool BranchProbabilityAnalysis::calcLoopBranchHeuristics(BasicBlock *BB) {
+bool BranchProbabilityInfo::calcLoopBranchHeuristics(BasicBlock *BB) {
uint32_t numSuccs = BB->getTerminator()->getNumSuccessors();
Loop *L = LI->getLoopFor(BB);
@@ -293,7 +252,7 @@
for (SmallPtrSet<BasicBlock *, 8>::iterator EI = BackEdges.begin(),
EE = BackEdges.end(); EI != EE; ++EI) {
BasicBlock *Back = *EI;
- BP->setEdgeWeight(BB, Back, backWeight);
+ setEdgeWeight(BB, Back, backWeight);
}
}
@@ -305,7 +264,7 @@
for (SmallPtrSet<BasicBlock *, 8>::iterator EI = InEdges.begin(),
EE = InEdges.end(); EI != EE; ++EI) {
BasicBlock *Back = *EI;
- BP->setEdgeWeight(BB, Back, inWeight);
+ setEdgeWeight(BB, Back, inWeight);
}
}
@@ -318,14 +277,14 @@
for (SmallPtrSet<BasicBlock *, 8>::iterator EI = ExitingEdges.begin(),
EE = ExitingEdges.end(); EI != EE; ++EI) {
BasicBlock *Exiting = *EI;
- BP->setEdgeWeight(BB, Exiting, exitWeight);
+ setEdgeWeight(BB, Exiting, exitWeight);
}
}
return true;
}
-bool BranchProbabilityAnalysis::calcZeroHeuristics(BasicBlock *BB) {
+bool BranchProbabilityInfo::calcZeroHeuristics(BasicBlock *BB) {
BranchInst * BI = dyn_cast<BranchInst>(BB->getTerminator());
if (!BI || !BI->isConditional())
return false;
@@ -380,13 +339,13 @@
if (!isProb)
std::swap(Taken, NonTaken);
- BP->setEdgeWeight(BB, Taken, ZH_TAKEN_WEIGHT);
- BP->setEdgeWeight(BB, NonTaken, ZH_NONTAKEN_WEIGHT);
+ setEdgeWeight(BB, Taken, ZH_TAKEN_WEIGHT);
+ setEdgeWeight(BB, NonTaken, ZH_NONTAKEN_WEIGHT);
return true;
}
-bool BranchProbabilityAnalysis::calcFloatingPointHeuristics(BasicBlock *BB) {
+bool BranchProbabilityInfo::calcFloatingPointHeuristics(BasicBlock *BB) {
BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
if (!BI || !BI->isConditional())
return false;
@@ -417,13 +376,21 @@
if (!isProb)
std::swap(Taken, NonTaken);
- BP->setEdgeWeight(BB, Taken, FPH_TAKEN_WEIGHT);
- BP->setEdgeWeight(BB, NonTaken, FPH_NONTAKEN_WEIGHT);
+ setEdgeWeight(BB, Taken, FPH_TAKEN_WEIGHT);
+ setEdgeWeight(BB, NonTaken, FPH_NONTAKEN_WEIGHT);
return true;
}
-bool BranchProbabilityAnalysis::runOnFunction(Function &F) {
+void BranchProbabilityInfo::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<LoopInfo>();
+ AU.setPreservesAll();
+}
+
+bool BranchProbabilityInfo::runOnFunction(Function &F) {
+ LastF = &F; // Store the last function we ran on for printing.
+ LI = &getAnalysis<LoopInfo>();
+
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
if (calcMetadataWeights(I))
continue;
@@ -440,18 +407,6 @@
return false;
}
-void BranchProbabilityInfo::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<LoopInfo>();
- AU.setPreservesAll();
-}
-
-bool BranchProbabilityInfo::runOnFunction(Function &F) {
- LastF = &F; // Store the last function we ran on for printing.
- LoopInfo &LI = getAnalysis<LoopInfo>();
- BranchProbabilityAnalysis BPA(this, &LI);
- return BPA.runOnFunction(F);
-}
-
void BranchProbabilityInfo::print(raw_ostream &OS, const Module *) const {
OS << "---- Branch Probabilities ----\n";
// We print the probabilities from the last function the analysis ran over,
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