LLVM API Documentation

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 #include "llvm/Transforms/Instrumentation.h"
00028 using namespace llvm;
00029 
00030 namespace llvm {
00031 
00032 namespace {
00033   enum Color{
00034     WHITE,
00035     GREY,
00036     BLACK
00037   };
00038 
00039   struct EmitFunctionTable : public ModulePass {
00040     bool runOnModule(Module &M);
00041   };
00042 
00043   RegisterOpt<EmitFunctionTable>
00044   X("emitfuncs", "Emit a function table for the reoptimizer");
00045 }
00046 
00047 static char doDFS(BasicBlock * node,std::map<BasicBlock *, Color > &color){
00048   color[node] = GREY;
00049 
00050   for(succ_iterator vl = succ_begin(node), ve = succ_end(node); vl != ve; ++vl){
00051 
00052     BasicBlock *BB = *vl;
00053 
00054     if(color[BB]!=GREY && color[BB]!=BLACK){
00055       if(!doDFS(BB, color)){
00056         return 0;
00057       }
00058     }
00059 
00060     //if has backedge
00061     else if(color[BB]==GREY)
00062       return 0;
00063 
00064   }
00065 
00066   color[node] = BLACK;
00067   return 1;
00068 }
00069 
00070 static char hasBackEdge(Function *F){
00071   std::map<BasicBlock *, Color > color;
00072   return doDFS(F->begin(), color);
00073 }
00074 
00075 // Per Module pass for inserting function table
00076 bool EmitFunctionTable::runOnModule(Module &M){
00077   std::vector<const Type*> vType;
00078 
00079   std::vector<Constant *> vConsts;
00080   std::vector<Constant *> sBCons;
00081 
00082   unsigned int counter = 0;
00083   for(Module::iterator MI = M.begin(), ME = M.end(); MI != ME; ++MI)
00084     if (!MI->isExternal()) {
00085       vType.push_back(MI->getType());
00086 
00087       //std::cerr<<MI;
00088 
00089       vConsts.push_back(MI);
00090       sBCons.push_back(ConstantInt::get(Type::SByteTy, hasBackEdge(MI)));
00091 
00092       counter++;
00093     }
00094 
00095   StructType *sttype = StructType::get(vType);
00096   Constant *cstruct = ConstantStruct::get(sttype, vConsts);
00097 
00098   GlobalVariable *gb = new GlobalVariable(cstruct->getType(), true,
00099                                           GlobalValue::ExternalLinkage,
00100                                           cstruct, "llvmFunctionTable");
00101   M.getGlobalList().push_back(gb);
00102 
00103   Constant *constArray = ConstantArray::get(ArrayType::get(Type::SByteTy,
00104                                                                 sBCons.size()),
00105                                                  sBCons);
00106 
00107   GlobalVariable *funcArray = new GlobalVariable(constArray->getType(), true,
00108                                               GlobalValue::ExternalLinkage,
00109                                               constArray, "llvmSimpleFunction");
00110 
00111   M.getGlobalList().push_back(funcArray);
00112 
00113   ConstantInt *cnst = ConstantSInt::get(Type::IntTy, counter);
00114   GlobalVariable *fnCount = new GlobalVariable(Type::IntTy, true,
00115                                                GlobalValue::ExternalLinkage,
00116                                                cnst, "llvmFunctionCount");
00117   M.getGlobalList().push_back(fnCount);
00118   return true;  // Always modifies program
00119 }
00120 
00121 ModulePass *createEmitFunctionTablePass () {
00122   return new EmitFunctionTable();
00123 }
00124 
00125 } // end namespace llvm