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EmitFunctions.cpp

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00001 //===-- EmitFunctions.cpp - interface to insert instrumentation -----------===//
00002 // 
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by the LLVM research group and is distributed under
00006 // the University of Illinois Open Source License. See LICENSE.TXT for details.
00007 // 
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This inserts into the input module three new global constants containing
00011 // mapping information pertinent to the Reoptimizer's runtime library:
00012 // 1) a structure containing a pointer to each function;
00013 // 2) an array containing a boolean which is true iff the corresponding
00014 //    function in 1) contains a back-edge branch suitable for the Reoptimizer's
00015 //    first-level instrumentation;
00016 // 3) an integer containing the number of entries in 1) and 2).
00017 //
00018 // NOTE: This pass is used by the reoptimizer only.
00019 //
00020 //===----------------------------------------------------------------------===//
00021 
00022 #include "llvm/Constants.h"
00023 #include "llvm/DerivedTypes.h"
00024 #include "llvm/Module.h"
00025 #include "llvm/Pass.h"
00026 #include "llvm/Support/CFG.h"
00027 using namespace llvm;
00028 
00029 namespace llvm { 
00030 
00031 namespace {
00032   enum Color{
00033     WHITE,
00034     GREY,
00035     BLACK
00036   };
00037   
00038   struct EmitFunctionTable : public ModulePass {
00039     bool runOnModule(Module &M);
00040   };
00041   
00042   RegisterOpt<EmitFunctionTable>
00043   X("emitfuncs", "Emit a function table for the reoptimizer");
00044 }
00045 
00046 static char doDFS(BasicBlock * node,std::map<BasicBlock *, Color > &color){
00047   color[node] = GREY;
00048 
00049   for(succ_iterator vl = succ_begin(node), ve = succ_end(node); vl != ve; ++vl){
00050    
00051     BasicBlock *BB = *vl; 
00052     
00053     if(color[BB]!=GREY && color[BB]!=BLACK){
00054       if(!doDFS(BB, color)){
00055   return 0;
00056       }
00057     }
00058 
00059     //if has backedge
00060     else if(color[BB]==GREY)
00061       return 0;
00062 
00063   }
00064 
00065   color[node] = BLACK;
00066   return 1;
00067 }
00068 
00069 static char hasBackEdge(Function *F){
00070   std::map<BasicBlock *, Color > color;
00071   return doDFS(F->begin(), color);
00072 }
00073 
00074 // Per Module pass for inserting function table
00075 bool EmitFunctionTable::runOnModule(Module &M){
00076   std::vector<const Type*> vType;
00077  
00078   std::vector<Constant *> vConsts;
00079   std::vector<Constant *> sBCons;
00080 
00081   unsigned int counter = 0;
00082   for(Module::iterator MI = M.begin(), ME = M.end(); MI != ME; ++MI)
00083     if (!MI->isExternal()) {
00084       vType.push_back(MI->getType());
00085     
00086       //std::cerr<<MI;
00087 
00088       vConsts.push_back(MI);
00089       sBCons.push_back(ConstantInt::get(Type::SByteTy, hasBackEdge(MI)));
00090       
00091       counter++;
00092     }
00093   
00094   StructType *sttype = StructType::get(vType);
00095   Constant *cstruct = ConstantStruct::get(sttype, vConsts);
00096 
00097   GlobalVariable *gb = new GlobalVariable(cstruct->getType(), true,
00098                                           GlobalValue::ExternalLinkage, 
00099                                           cstruct, "llvmFunctionTable");
00100   M.getGlobalList().push_back(gb);
00101 
00102   Constant *constArray = ConstantArray::get(ArrayType::get(Type::SByteTy, 
00103                 sBCons.size()),
00104              sBCons);
00105 
00106   GlobalVariable *funcArray = new GlobalVariable(constArray->getType(), true,
00107                 GlobalValue::ExternalLinkage,
00108                 constArray, "llvmSimpleFunction");
00109 
00110   M.getGlobalList().push_back(funcArray);
00111 
00112   ConstantInt *cnst = ConstantSInt::get(Type::IntTy, counter); 
00113   GlobalVariable *fnCount = new GlobalVariable(Type::IntTy, true, 
00114                  GlobalValue::ExternalLinkage, 
00115                  cnst, "llvmFunctionCount");
00116   M.getGlobalList().push_back(fnCount);
00117   return true;  // Always modifies program
00118 }
00119 
00120 ModulePass *createEmitFunctionTablePass () {
00121   return new EmitFunctionTable();
00122 }
00123 
00124 } // end namespace llvm