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1 //=======-------- BlockFrequencyInfo.cpp - Block Frequency Analysis -------=======//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Loops should be simplified before this analysis.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/InitializePasses.h"
15 #include "llvm/Analysis/BlockFrequencyImpl.h"
16 #include "llvm/Analysis/BlockFrequencyInfo.h"
17 #include "llvm/Analysis/LoopInfo.h"
18 #include "llvm/Analysis/Passes.h"
19 #include "llvm/Analysis/BranchProbabilityInfo.h"
20 
21 using namespace llvm;
22 
23 INITIALIZE_PASS_BEGIN(BlockFrequencyInfo, "block-freq", "Block Frequency Analysis",
24                       true, true)
25 INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfo)
26 INITIALIZE_PASS_END(BlockFrequencyInfo, "block-freq", "Block Frequency Analysis",
27                     true, true)
28 
29 char BlockFrequencyInfo::ID = 0;
30 
31 
BlockFrequencyInfo()32 BlockFrequencyInfo::BlockFrequencyInfo() : FunctionPass(ID) {
33   initializeBlockFrequencyInfoPass(*PassRegistry::getPassRegistry());
34   BFI = new BlockFrequencyImpl<BasicBlock, Function, BranchProbabilityInfo>();
35 }
36 
~BlockFrequencyInfo()37 BlockFrequencyInfo::~BlockFrequencyInfo() {
38   delete BFI;
39 }
40 
getAnalysisUsage(AnalysisUsage & AU) const41 void BlockFrequencyInfo::getAnalysisUsage(AnalysisUsage &AU) const {
42   AU.addRequired<BranchProbabilityInfo>();
43   AU.setPreservesAll();
44 }
45 
runOnFunction(Function & F)46 bool BlockFrequencyInfo::runOnFunction(Function &F) {
47   BranchProbabilityInfo &BPI = getAnalysis<BranchProbabilityInfo>();
48   BFI->doFunction(&F, &BPI);
49   return false;
50 }
51 
print(raw_ostream & O,const Module *) const52 void BlockFrequencyInfo::print(raw_ostream &O, const Module *) const {
53   if (BFI) BFI->print(O);
54 }
55 
56 /// getblockFreq - Return block frequency. Return 0 if we don't have the
57 /// information. Please note that initial frequency is equal to 1024. It means
58 /// that we should not rely on the value itself, but only on the comparison to
59 /// the other block frequencies. We do this to avoid using of floating points.
60 ///
getBlockFreq(BasicBlock * BB) const61 BlockFrequency BlockFrequencyInfo::getBlockFreq(BasicBlock *BB) const {
62   return BFI->getBlockFreq(BB);
63 }
64