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98 lines
3.3 KiB
C++
98 lines
3.3 KiB
C++
//===- ProfileInfo.cpp - Profile Info Interface ---------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the abstract ProfileInfo interface, and the default
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// "no profile" implementation.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/Passes.h"
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#include "llvm/Analysis/ProfileInfo.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/CFG.h"
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#include "llvm/Support/Compiler.h"
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#include <set>
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using namespace llvm;
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// Register the ProfileInfo interface, providing a nice name to refer to.
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namespace {
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RegisterAnalysisGroup<ProfileInfo> Z("Profile Information");
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}
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ProfileInfo::~ProfileInfo() {}
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unsigned ProfileInfo::getExecutionCount(BasicBlock *BB) const {
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pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
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// Are there zero predecessors of this block?
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if (PI == PE) {
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// If this is the entry block, look for the Null -> Entry edge.
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if (BB == &BB->getParent()->getEntryBlock())
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return getEdgeWeight(0, BB);
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else
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return 0; // Otherwise, this is a dead block.
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}
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// Otherwise, if there are predecessors, the execution count of this block is
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// the sum of the edge frequencies from the incoming edges. Note that if
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// there are multiple edges from a predecessor to this block that we don't
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// want to count its weight multiple times. For this reason, we keep track of
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// the predecessors we've seen and only count them if we haven't run into them
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// yet.
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//
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// We don't want to create an std::set unless we are dealing with a block that
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// has a LARGE number of in-edges. Handle the common case of having only a
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// few in-edges with special code.
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//
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BasicBlock *FirstPred = *PI;
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unsigned Count = getEdgeWeight(FirstPred, BB);
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++PI;
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if (PI == PE) return Count; // Quick exit for single predecessor blocks
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BasicBlock *SecondPred = *PI;
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if (SecondPred != FirstPred) Count += getEdgeWeight(SecondPred, BB);
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++PI;
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if (PI == PE) return Count; // Quick exit for two predecessor blocks
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BasicBlock *ThirdPred = *PI;
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if (ThirdPred != FirstPred && ThirdPred != SecondPred)
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Count += getEdgeWeight(ThirdPred, BB);
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++PI;
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if (PI == PE) return Count; // Quick exit for three predecessor blocks
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std::set<BasicBlock*> ProcessedPreds;
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ProcessedPreds.insert(FirstPred);
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ProcessedPreds.insert(SecondPred);
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ProcessedPreds.insert(ThirdPred);
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for (; PI != PE; ++PI)
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if (ProcessedPreds.insert(*PI).second)
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Count += getEdgeWeight(*PI, BB);
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return Count;
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}
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//===----------------------------------------------------------------------===//
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// NoProfile ProfileInfo implementation
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//
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namespace {
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struct VISIBILITY_HIDDEN NoProfileInfo
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: public ImmutablePass, public ProfileInfo {};
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// Register this pass...
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RegisterPass<NoProfileInfo>
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X("no-profile", "No Profile Information");
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// Declare that we implement the ProfileInfo interface
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RegisterAnalysisGroup<ProfileInfo, true> Y(X);
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} // End of anonymous namespace
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ImmutablePass *llvm::createNoProfileInfoPass() { return new NoProfileInfo(); }
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