1 //===---- CodePreparation.cpp - Code preparation for Scop Detection -------===//
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 // The Polly code preparation pass is executed before SCoP detection. Its
11 // currently only splits the entry block of the SCoP to make room for alloc
12 // instructions as they are generated during code generation.
13 //
14 // XXX: In the future, we should remove the need for this pass entirely and
15 // instead add this spitting to the code generation pass.
16 //
17 //===----------------------------------------------------------------------===//
18 
19 #include "polly/LinkAllPasses.h"
20 #include "polly/CodeGen/BlockGenerators.h"
21 #include "polly/ScopDetection.h"
22 #include "polly/Support/ScopHelper.h"
23 #include "llvm/Analysis/DominanceFrontier.h"
24 #include "llvm/Analysis/LoopInfo.h"
25 #include "llvm/Analysis/RegionInfo.h"
26 #include "llvm/Analysis/ScalarEvolution.h"
27 #include "llvm/Transforms/Utils/Local.h"
28 
29 using namespace llvm;
30 using namespace polly;
31 
32 namespace {
33 
34 /// @brief Prepare the IR for the scop detection.
35 ///
36 class CodePreparation : public FunctionPass {
37   CodePreparation(const CodePreparation &) = delete;
38   const CodePreparation &operator=(const CodePreparation &) = delete;
39 
40   LoopInfo *LI;
41   ScalarEvolution *SE;
42 
43   void clear();
44 
45   bool eliminatePHINodes(Function &F);
46 
47 public:
48   static char ID;
49 
50   explicit CodePreparation() : FunctionPass(ID) {}
51   ~CodePreparation();
52 
53   /// @name FunctionPass interface.
54   //@{
55   virtual void getAnalysisUsage(AnalysisUsage &AU) const;
56   virtual void releaseMemory();
57   virtual bool runOnFunction(Function &F);
58   virtual void print(raw_ostream &OS, const Module *) const;
59   //@}
60 };
61 }
62 
63 void CodePreparation::clear() {}
64 
65 CodePreparation::~CodePreparation() { clear(); }
66 
67 void CodePreparation::getAnalysisUsage(AnalysisUsage &AU) const {
68   AU.addRequired<LoopInfoWrapperPass>();
69   AU.addRequired<ScalarEvolutionWrapperPass>();
70 
71   AU.addPreserved<LoopInfoWrapperPass>();
72   AU.addPreserved<RegionInfoPass>();
73   AU.addPreserved<DominatorTreeWrapperPass>();
74   AU.addPreserved<DominanceFrontier>();
75 }
76 
77 bool CodePreparation::runOnFunction(Function &F) {
78   LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
79   SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
80 
81   splitEntryBlockForAlloca(&F.getEntryBlock(), this);
82 
83   return false;
84 }
85 
86 void CodePreparation::releaseMemory() { clear(); }
87 
88 void CodePreparation::print(raw_ostream &OS, const Module *) const {}
89 
90 char CodePreparation::ID = 0;
91 char &polly::CodePreparationID = CodePreparation::ID;
92 
93 Pass *polly::createCodePreparationPass() { return new CodePreparation(); }
94 
95 INITIALIZE_PASS_BEGIN(CodePreparation, "polly-prepare",
96                       "Polly - Prepare code for polly", false, false)
97 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
98 INITIALIZE_PASS_END(CodePreparation, "polly-prepare",
99                     "Polly - Prepare code for polly", false, false)
100