forked from OSchip/llvm-project
663 lines
21 KiB
C++
663 lines
21 KiB
C++
//===-- BranchProbabilityInfo.cpp - Branch Probability Analysis -----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Loops should be simplified before this analysis.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "branch-prob"
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#include "llvm/Analysis/BranchProbabilityInfo.h"
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#include "llvm/ADT/PostOrderIterator.h"
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/IR/CFG.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/Metadata.h"
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#include "llvm/Support/Debug.h"
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using namespace llvm;
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INITIALIZE_PASS_BEGIN(BranchProbabilityInfo, "branch-prob",
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"Branch Probability Analysis", false, true)
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INITIALIZE_PASS_DEPENDENCY(LoopInfo)
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INITIALIZE_PASS_END(BranchProbabilityInfo, "branch-prob",
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"Branch Probability Analysis", false, true)
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char BranchProbabilityInfo::ID = 0;
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// Weights are for internal use only. They are used by heuristics to help to
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// estimate edges' probability. Example:
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//
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// Using "Loop Branch Heuristics" we predict weights of edges for the
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// block BB2.
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// ...
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// |
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// V
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// BB1<-+
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// | |
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// | | (Weight = 124)
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// V |
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// BB2--+
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// |
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// | (Weight = 4)
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// V
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// BB3
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//
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// Probability of the edge BB2->BB1 = 124 / (124 + 4) = 0.96875
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// Probability of the edge BB2->BB3 = 4 / (124 + 4) = 0.03125
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static const uint32_t LBH_TAKEN_WEIGHT = 124;
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static const uint32_t LBH_NONTAKEN_WEIGHT = 4;
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/// \brief Unreachable-terminating branch taken weight.
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///
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/// This is the weight for a branch being taken to a block that terminates
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/// (eventually) in unreachable. These are predicted as unlikely as possible.
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static const uint32_t UR_TAKEN_WEIGHT = 1;
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/// \brief Unreachable-terminating branch not-taken weight.
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///
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/// This is the weight for a branch not being taken toward a block that
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/// terminates (eventually) in unreachable. Such a branch is essentially never
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/// taken. Set the weight to an absurdly high value so that nested loops don't
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/// easily subsume it.
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static const uint32_t UR_NONTAKEN_WEIGHT = 1024*1024 - 1;
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/// \brief Weight for a branch taken going into a cold block.
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///
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/// This is the weight for a branch taken toward a block marked
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/// cold. A block is marked cold if it's postdominated by a
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/// block containing a call to a cold function. Cold functions
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/// are those marked with attribute 'cold'.
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static const uint32_t CC_TAKEN_WEIGHT = 4;
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/// \brief Weight for a branch not-taken into a cold block.
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///
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/// This is the weight for a branch not taken toward a block marked
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/// cold.
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static const uint32_t CC_NONTAKEN_WEIGHT = 64;
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static const uint32_t PH_TAKEN_WEIGHT = 20;
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static const uint32_t PH_NONTAKEN_WEIGHT = 12;
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static const uint32_t ZH_TAKEN_WEIGHT = 20;
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static const uint32_t ZH_NONTAKEN_WEIGHT = 12;
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static const uint32_t FPH_TAKEN_WEIGHT = 20;
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static const uint32_t FPH_NONTAKEN_WEIGHT = 12;
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/// \brief Invoke-terminating normal branch taken weight
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///
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/// This is the weight for branching to the normal destination of an invoke
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/// instruction. We expect this to happen most of the time. Set the weight to an
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/// absurdly high value so that nested loops subsume it.
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static const uint32_t IH_TAKEN_WEIGHT = 1024 * 1024 - 1;
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/// \brief Invoke-terminating normal branch not-taken weight.
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///
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/// This is the weight for branching to the unwind destination of an invoke
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/// instruction. This is essentially never taken.
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static const uint32_t IH_NONTAKEN_WEIGHT = 1;
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// Standard weight value. Used when none of the heuristics set weight for
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// the edge.
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static const uint32_t NORMAL_WEIGHT = 16;
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// Minimum weight of an edge. Please note, that weight is NEVER 0.
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static const uint32_t MIN_WEIGHT = 1;
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static uint32_t getMaxWeightFor(BasicBlock *BB) {
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return UINT32_MAX / BB->getTerminator()->getNumSuccessors();
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}
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/// \brief Calculate edge weights for successors lead to unreachable.
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///
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/// Predict that a successor which leads necessarily to an
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/// unreachable-terminated block as extremely unlikely.
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bool BranchProbabilityInfo::calcUnreachableHeuristics(BasicBlock *BB) {
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TerminatorInst *TI = BB->getTerminator();
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if (TI->getNumSuccessors() == 0) {
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if (isa<UnreachableInst>(TI))
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PostDominatedByUnreachable.insert(BB);
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return false;
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}
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SmallVector<unsigned, 4> UnreachableEdges;
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SmallVector<unsigned, 4> ReachableEdges;
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for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I) {
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if (PostDominatedByUnreachable.count(*I))
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UnreachableEdges.push_back(I.getSuccessorIndex());
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else
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ReachableEdges.push_back(I.getSuccessorIndex());
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}
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// If all successors are in the set of blocks post-dominated by unreachable,
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// this block is too.
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if (UnreachableEdges.size() == TI->getNumSuccessors())
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PostDominatedByUnreachable.insert(BB);
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// Skip probabilities if this block has a single successor or if all were
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// reachable.
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if (TI->getNumSuccessors() == 1 || UnreachableEdges.empty())
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return false;
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uint32_t UnreachableWeight =
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std::max(UR_TAKEN_WEIGHT / (unsigned)UnreachableEdges.size(), MIN_WEIGHT);
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for (SmallVectorImpl<unsigned>::iterator I = UnreachableEdges.begin(),
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E = UnreachableEdges.end();
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I != E; ++I)
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setEdgeWeight(BB, *I, UnreachableWeight);
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if (ReachableEdges.empty())
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return true;
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uint32_t ReachableWeight =
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std::max(UR_NONTAKEN_WEIGHT / (unsigned)ReachableEdges.size(),
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NORMAL_WEIGHT);
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for (SmallVectorImpl<unsigned>::iterator I = ReachableEdges.begin(),
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E = ReachableEdges.end();
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I != E; ++I)
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setEdgeWeight(BB, *I, ReachableWeight);
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return true;
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}
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// Propagate existing explicit probabilities from either profile data or
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// 'expect' intrinsic processing.
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bool BranchProbabilityInfo::calcMetadataWeights(BasicBlock *BB) {
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TerminatorInst *TI = BB->getTerminator();
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if (TI->getNumSuccessors() == 1)
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return false;
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if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
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return false;
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MDNode *WeightsNode = TI->getMetadata(LLVMContext::MD_prof);
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if (!WeightsNode)
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return false;
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// Ensure there are weights for all of the successors. Note that the first
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// operand to the metadata node is a name, not a weight.
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if (WeightsNode->getNumOperands() != TI->getNumSuccessors() + 1)
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return false;
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// Build up the final weights that will be used in a temporary buffer, but
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// don't add them until all weihts are present. Each weight value is clamped
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// to [1, getMaxWeightFor(BB)].
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uint32_t WeightLimit = getMaxWeightFor(BB);
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SmallVector<uint32_t, 2> Weights;
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Weights.reserve(TI->getNumSuccessors());
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for (unsigned i = 1, e = WeightsNode->getNumOperands(); i != e; ++i) {
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ConstantInt *Weight = dyn_cast<ConstantInt>(WeightsNode->getOperand(i));
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if (!Weight)
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return false;
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Weights.push_back(
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std::max<uint32_t>(1, Weight->getLimitedValue(WeightLimit)));
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}
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assert(Weights.size() == TI->getNumSuccessors() && "Checked above");
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for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
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setEdgeWeight(BB, i, Weights[i]);
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return true;
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}
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/// \brief Calculate edge weights for edges leading to cold blocks.
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///
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/// A cold block is one post-dominated by a block with a call to a
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/// cold function. Those edges are unlikely to be taken, so we give
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/// them relatively low weight.
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///
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/// Return true if we could compute the weights for cold edges.
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/// Return false, otherwise.
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bool BranchProbabilityInfo::calcColdCallHeuristics(BasicBlock *BB) {
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TerminatorInst *TI = BB->getTerminator();
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if (TI->getNumSuccessors() == 0)
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return false;
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// Determine which successors are post-dominated by a cold block.
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SmallVector<unsigned, 4> ColdEdges;
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SmallVector<unsigned, 4> NormalEdges;
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for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
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if (PostDominatedByColdCall.count(*I))
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ColdEdges.push_back(I.getSuccessorIndex());
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else
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NormalEdges.push_back(I.getSuccessorIndex());
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// If all successors are in the set of blocks post-dominated by cold calls,
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// this block is in the set post-dominated by cold calls.
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if (ColdEdges.size() == TI->getNumSuccessors())
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PostDominatedByColdCall.insert(BB);
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else {
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// Otherwise, if the block itself contains a cold function, add it to the
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// set of blocks postdominated by a cold call.
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assert(!PostDominatedByColdCall.count(BB));
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for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
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if (CallInst *CI = dyn_cast<CallInst>(I))
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if (CI->hasFnAttr(Attribute::Cold)) {
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PostDominatedByColdCall.insert(BB);
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break;
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}
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}
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// Skip probabilities if this block has a single successor.
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if (TI->getNumSuccessors() == 1 || ColdEdges.empty())
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return false;
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uint32_t ColdWeight =
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std::max(CC_TAKEN_WEIGHT / (unsigned) ColdEdges.size(), MIN_WEIGHT);
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for (SmallVectorImpl<unsigned>::iterator I = ColdEdges.begin(),
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E = ColdEdges.end();
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I != E; ++I)
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setEdgeWeight(BB, *I, ColdWeight);
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if (NormalEdges.empty())
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return true;
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uint32_t NormalWeight = std::max(
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CC_NONTAKEN_WEIGHT / (unsigned) NormalEdges.size(), NORMAL_WEIGHT);
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for (SmallVectorImpl<unsigned>::iterator I = NormalEdges.begin(),
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E = NormalEdges.end();
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I != E; ++I)
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setEdgeWeight(BB, *I, NormalWeight);
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return true;
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}
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// Calculate Edge Weights using "Pointer Heuristics". Predict a comparsion
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// between two pointer or pointer and NULL will fail.
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bool BranchProbabilityInfo::calcPointerHeuristics(BasicBlock *BB) {
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BranchInst * BI = dyn_cast<BranchInst>(BB->getTerminator());
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if (!BI || !BI->isConditional())
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return false;
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Value *Cond = BI->getCondition();
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ICmpInst *CI = dyn_cast<ICmpInst>(Cond);
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if (!CI || !CI->isEquality())
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return false;
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Value *LHS = CI->getOperand(0);
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if (!LHS->getType()->isPointerTy())
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return false;
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assert(CI->getOperand(1)->getType()->isPointerTy());
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// p != 0 -> isProb = true
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// p == 0 -> isProb = false
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// p != q -> isProb = true
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// p == q -> isProb = false;
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unsigned TakenIdx = 0, NonTakenIdx = 1;
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bool isProb = CI->getPredicate() == ICmpInst::ICMP_NE;
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if (!isProb)
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std::swap(TakenIdx, NonTakenIdx);
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setEdgeWeight(BB, TakenIdx, PH_TAKEN_WEIGHT);
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setEdgeWeight(BB, NonTakenIdx, PH_NONTAKEN_WEIGHT);
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return true;
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}
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// Calculate Edge Weights using "Loop Branch Heuristics". Predict backedges
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// as taken, exiting edges as not-taken.
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bool BranchProbabilityInfo::calcLoopBranchHeuristics(BasicBlock *BB) {
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Loop *L = LI->getLoopFor(BB);
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if (!L)
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return false;
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SmallVector<unsigned, 8> BackEdges;
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SmallVector<unsigned, 8> ExitingEdges;
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SmallVector<unsigned, 8> InEdges; // Edges from header to the loop.
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for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I) {
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if (!L->contains(*I))
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ExitingEdges.push_back(I.getSuccessorIndex());
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else if (L->getHeader() == *I)
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BackEdges.push_back(I.getSuccessorIndex());
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else
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InEdges.push_back(I.getSuccessorIndex());
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}
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if (BackEdges.empty() && ExitingEdges.empty())
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return false;
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if (uint32_t numBackEdges = BackEdges.size()) {
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uint32_t backWeight = LBH_TAKEN_WEIGHT / numBackEdges;
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if (backWeight < NORMAL_WEIGHT)
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backWeight = NORMAL_WEIGHT;
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for (SmallVectorImpl<unsigned>::iterator EI = BackEdges.begin(),
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EE = BackEdges.end(); EI != EE; ++EI) {
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setEdgeWeight(BB, *EI, backWeight);
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}
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}
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if (uint32_t numInEdges = InEdges.size()) {
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uint32_t inWeight = LBH_TAKEN_WEIGHT / numInEdges;
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if (inWeight < NORMAL_WEIGHT)
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inWeight = NORMAL_WEIGHT;
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for (SmallVectorImpl<unsigned>::iterator EI = InEdges.begin(),
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EE = InEdges.end(); EI != EE; ++EI) {
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setEdgeWeight(BB, *EI, inWeight);
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}
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}
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if (uint32_t numExitingEdges = ExitingEdges.size()) {
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uint32_t exitWeight = LBH_NONTAKEN_WEIGHT / numExitingEdges;
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if (exitWeight < MIN_WEIGHT)
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exitWeight = MIN_WEIGHT;
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for (SmallVectorImpl<unsigned>::iterator EI = ExitingEdges.begin(),
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EE = ExitingEdges.end(); EI != EE; ++EI) {
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setEdgeWeight(BB, *EI, exitWeight);
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}
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}
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return true;
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}
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bool BranchProbabilityInfo::calcZeroHeuristics(BasicBlock *BB) {
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BranchInst * BI = dyn_cast<BranchInst>(BB->getTerminator());
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if (!BI || !BI->isConditional())
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return false;
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Value *Cond = BI->getCondition();
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ICmpInst *CI = dyn_cast<ICmpInst>(Cond);
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if (!CI)
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return false;
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Value *RHS = CI->getOperand(1);
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ConstantInt *CV = dyn_cast<ConstantInt>(RHS);
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if (!CV)
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return false;
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bool isProb;
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if (CV->isZero()) {
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switch (CI->getPredicate()) {
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case CmpInst::ICMP_EQ:
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// X == 0 -> Unlikely
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isProb = false;
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break;
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case CmpInst::ICMP_NE:
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// X != 0 -> Likely
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isProb = true;
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break;
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case CmpInst::ICMP_SLT:
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// X < 0 -> Unlikely
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isProb = false;
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break;
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case CmpInst::ICMP_SGT:
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// X > 0 -> Likely
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isProb = true;
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break;
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default:
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return false;
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}
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} else if (CV->isOne() && CI->getPredicate() == CmpInst::ICMP_SLT) {
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// InstCombine canonicalizes X <= 0 into X < 1.
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// X <= 0 -> Unlikely
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isProb = false;
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} else if (CV->isAllOnesValue()) {
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switch (CI->getPredicate()) {
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case CmpInst::ICMP_EQ:
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// X == -1 -> Unlikely
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isProb = false;
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break;
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case CmpInst::ICMP_NE:
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// X != -1 -> Likely
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isProb = true;
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break;
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case CmpInst::ICMP_SGT:
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// InstCombine canonicalizes X >= 0 into X > -1.
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// X >= 0 -> Likely
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isProb = true;
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break;
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default:
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return false;
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}
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} else {
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return false;
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}
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unsigned TakenIdx = 0, NonTakenIdx = 1;
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if (!isProb)
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std::swap(TakenIdx, NonTakenIdx);
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setEdgeWeight(BB, TakenIdx, ZH_TAKEN_WEIGHT);
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setEdgeWeight(BB, NonTakenIdx, ZH_NONTAKEN_WEIGHT);
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return true;
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}
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bool BranchProbabilityInfo::calcFloatingPointHeuristics(BasicBlock *BB) {
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BranchInst *BI = dyn_cast<BranchInst>(BB->getTerminator());
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if (!BI || !BI->isConditional())
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return false;
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Value *Cond = BI->getCondition();
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FCmpInst *FCmp = dyn_cast<FCmpInst>(Cond);
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if (!FCmp)
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return false;
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bool isProb;
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if (FCmp->isEquality()) {
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// f1 == f2 -> Unlikely
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// f1 != f2 -> Likely
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isProb = !FCmp->isTrueWhenEqual();
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} else if (FCmp->getPredicate() == FCmpInst::FCMP_ORD) {
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// !isnan -> Likely
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isProb = true;
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} else if (FCmp->getPredicate() == FCmpInst::FCMP_UNO) {
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// isnan -> Unlikely
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isProb = false;
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} else {
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return false;
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}
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unsigned TakenIdx = 0, NonTakenIdx = 1;
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if (!isProb)
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std::swap(TakenIdx, NonTakenIdx);
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setEdgeWeight(BB, TakenIdx, FPH_TAKEN_WEIGHT);
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setEdgeWeight(BB, NonTakenIdx, FPH_NONTAKEN_WEIGHT);
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return true;
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}
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bool BranchProbabilityInfo::calcInvokeHeuristics(BasicBlock *BB) {
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InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator());
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if (!II)
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return false;
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setEdgeWeight(BB, 0/*Index for Normal*/, IH_TAKEN_WEIGHT);
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setEdgeWeight(BB, 1/*Index for Unwind*/, IH_NONTAKEN_WEIGHT);
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return true;
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}
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void BranchProbabilityInfo::getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<LoopInfo>();
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AU.setPreservesAll();
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}
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bool BranchProbabilityInfo::runOnFunction(Function &F) {
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DEBUG(dbgs() << "---- Branch Probability Info : " << F.getName()
|
|
<< " ----\n\n");
|
|
LastF = &F; // Store the last function we ran on for printing.
|
|
LI = &getAnalysis<LoopInfo>();
|
|
assert(PostDominatedByUnreachable.empty());
|
|
assert(PostDominatedByColdCall.empty());
|
|
|
|
// Walk the basic blocks in post-order so that we can build up state about
|
|
// the successors of a block iteratively.
|
|
for (po_iterator<BasicBlock *> I = po_begin(&F.getEntryBlock()),
|
|
E = po_end(&F.getEntryBlock());
|
|
I != E; ++I) {
|
|
DEBUG(dbgs() << "Computing probabilities for " << I->getName() << "\n");
|
|
if (calcUnreachableHeuristics(*I))
|
|
continue;
|
|
if (calcMetadataWeights(*I))
|
|
continue;
|
|
if (calcColdCallHeuristics(*I))
|
|
continue;
|
|
if (calcLoopBranchHeuristics(*I))
|
|
continue;
|
|
if (calcPointerHeuristics(*I))
|
|
continue;
|
|
if (calcZeroHeuristics(*I))
|
|
continue;
|
|
if (calcFloatingPointHeuristics(*I))
|
|
continue;
|
|
calcInvokeHeuristics(*I);
|
|
}
|
|
|
|
PostDominatedByUnreachable.clear();
|
|
PostDominatedByColdCall.clear();
|
|
return false;
|
|
}
|
|
|
|
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,
|
|
// or the function it is currently running over.
|
|
assert(LastF && "Cannot print prior to running over a function");
|
|
for (Function::const_iterator BI = LastF->begin(), BE = LastF->end();
|
|
BI != BE; ++BI) {
|
|
for (succ_const_iterator SI = succ_begin(BI), SE = succ_end(BI);
|
|
SI != SE; ++SI) {
|
|
printEdgeProbability(OS << " ", BI, *SI);
|
|
}
|
|
}
|
|
}
|
|
|
|
uint32_t BranchProbabilityInfo::getSumForBlock(const BasicBlock *BB) const {
|
|
uint32_t Sum = 0;
|
|
|
|
for (succ_const_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I) {
|
|
uint32_t Weight = getEdgeWeight(BB, I.getSuccessorIndex());
|
|
uint32_t PrevSum = Sum;
|
|
|
|
Sum += Weight;
|
|
assert(Sum > PrevSum); (void) PrevSum;
|
|
}
|
|
|
|
return Sum;
|
|
}
|
|
|
|
bool BranchProbabilityInfo::
|
|
isEdgeHot(const BasicBlock *Src, const BasicBlock *Dst) const {
|
|
// Hot probability is at least 4/5 = 80%
|
|
// FIXME: Compare against a static "hot" BranchProbability.
|
|
return getEdgeProbability(Src, Dst) > BranchProbability(4, 5);
|
|
}
|
|
|
|
BasicBlock *BranchProbabilityInfo::getHotSucc(BasicBlock *BB) const {
|
|
uint32_t Sum = 0;
|
|
uint32_t MaxWeight = 0;
|
|
BasicBlock *MaxSucc = nullptr;
|
|
|
|
for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I) {
|
|
BasicBlock *Succ = *I;
|
|
uint32_t Weight = getEdgeWeight(BB, Succ);
|
|
uint32_t PrevSum = Sum;
|
|
|
|
Sum += Weight;
|
|
assert(Sum > PrevSum); (void) PrevSum;
|
|
|
|
if (Weight > MaxWeight) {
|
|
MaxWeight = Weight;
|
|
MaxSucc = Succ;
|
|
}
|
|
}
|
|
|
|
// Hot probability is at least 4/5 = 80%
|
|
if (BranchProbability(MaxWeight, Sum) > BranchProbability(4, 5))
|
|
return MaxSucc;
|
|
|
|
return nullptr;
|
|
}
|
|
|
|
/// Get the raw edge weight for the edge. If can't find it, return
|
|
/// DEFAULT_WEIGHT value. Here an edge is specified using PredBlock and an index
|
|
/// to the successors.
|
|
uint32_t BranchProbabilityInfo::
|
|
getEdgeWeight(const BasicBlock *Src, unsigned IndexInSuccessors) const {
|
|
DenseMap<Edge, uint32_t>::const_iterator I =
|
|
Weights.find(std::make_pair(Src, IndexInSuccessors));
|
|
|
|
if (I != Weights.end())
|
|
return I->second;
|
|
|
|
return DEFAULT_WEIGHT;
|
|
}
|
|
|
|
uint32_t BranchProbabilityInfo::getEdgeWeight(const BasicBlock *Src,
|
|
succ_const_iterator Dst) const {
|
|
return getEdgeWeight(Src, Dst.getSuccessorIndex());
|
|
}
|
|
|
|
/// Get the raw edge weight calculated for the block pair. This returns the sum
|
|
/// of all raw edge weights from Src to Dst.
|
|
uint32_t BranchProbabilityInfo::
|
|
getEdgeWeight(const BasicBlock *Src, const BasicBlock *Dst) const {
|
|
uint32_t Weight = 0;
|
|
DenseMap<Edge, uint32_t>::const_iterator MapI;
|
|
for (succ_const_iterator I = succ_begin(Src), E = succ_end(Src); I != E; ++I)
|
|
if (*I == Dst) {
|
|
MapI = Weights.find(std::make_pair(Src, I.getSuccessorIndex()));
|
|
if (MapI != Weights.end())
|
|
Weight += MapI->second;
|
|
}
|
|
return (Weight == 0) ? DEFAULT_WEIGHT : Weight;
|
|
}
|
|
|
|
/// Set the edge weight for a given edge specified by PredBlock and an index
|
|
/// to the successors.
|
|
void BranchProbabilityInfo::
|
|
setEdgeWeight(const BasicBlock *Src, unsigned IndexInSuccessors,
|
|
uint32_t Weight) {
|
|
Weights[std::make_pair(Src, IndexInSuccessors)] = Weight;
|
|
DEBUG(dbgs() << "set edge " << Src->getName() << " -> "
|
|
<< IndexInSuccessors << " successor weight to "
|
|
<< Weight << "\n");
|
|
}
|
|
|
|
/// Get an edge's probability, relative to other out-edges from Src.
|
|
BranchProbability BranchProbabilityInfo::
|
|
getEdgeProbability(const BasicBlock *Src, unsigned IndexInSuccessors) const {
|
|
uint32_t N = getEdgeWeight(Src, IndexInSuccessors);
|
|
uint32_t D = getSumForBlock(Src);
|
|
|
|
return BranchProbability(N, D);
|
|
}
|
|
|
|
/// Get the probability of going from Src to Dst. It returns the sum of all
|
|
/// probabilities for edges from Src to Dst.
|
|
BranchProbability BranchProbabilityInfo::
|
|
getEdgeProbability(const BasicBlock *Src, const BasicBlock *Dst) const {
|
|
|
|
uint32_t N = getEdgeWeight(Src, Dst);
|
|
uint32_t D = getSumForBlock(Src);
|
|
|
|
return BranchProbability(N, D);
|
|
}
|
|
|
|
raw_ostream &
|
|
BranchProbabilityInfo::printEdgeProbability(raw_ostream &OS,
|
|
const BasicBlock *Src,
|
|
const BasicBlock *Dst) const {
|
|
|
|
const BranchProbability Prob = getEdgeProbability(Src, Dst);
|
|
OS << "edge " << Src->getName() << " -> " << Dst->getName()
|
|
<< " probability is " << Prob
|
|
<< (isEdgeHot(Src, Dst) ? " [HOT edge]\n" : "\n");
|
|
|
|
return OS;
|
|
}
|