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TraceBasicBlocks.cpp

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00001 //===- TraceBasicBlocks.cpp - Insert basic-block trace 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 pass instruments the specified program with calls into a runtime
00011 // library that cause it to output a trace of basic blocks as a side effect
00012 // of normal execution.
00013 //
00014 //===----------------------------------------------------------------------===//
00015 
00016 #include "llvm/Constants.h"
00017 #include "llvm/DerivedTypes.h"
00018 #include "llvm/Module.h"
00019 #include "llvm/Pass.h"
00020 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
00021 #include "llvm/Instructions.h"
00022 #include "ProfilingUtils.h"
00023 #include "llvm/Support/Debug.h"
00024 #include <set>
00025 using namespace llvm;
00026 
00027 namespace {
00028   class TraceBasicBlocks : public ModulePass {
00029     bool runOnModule(Module &M);
00030   };
00031 
00032   RegisterOpt<TraceBasicBlocks> X("trace-basic-blocks",
00033                               "Insert instrumentation for basic block tracing");
00034 }
00035 
00036 static void InsertInstrumentationCall (BasicBlock *BB,
00037                                        const std::string FnName,
00038                                        unsigned BBNumber) {
00039   DEBUG (std::cerr << "InsertInstrumentationCall (\"" << BB->getName ()
00040                    << "\", \"" << FnName << "\", " << BBNumber << ")\n");
00041   Module &M = *BB->getParent ()->getParent ();
00042   Function *InstrFn = M.getOrInsertFunction (FnName, Type::VoidTy,
00043                                              Type::UIntTy, 0);
00044   std::vector<Value*> Args (1);
00045   Args[0] = ConstantUInt::get (Type::UIntTy, BBNumber);
00046 
00047   // Insert the call after any alloca or PHI instructions...
00048   BasicBlock::iterator InsertPos = BB->begin();
00049   while (isa<AllocaInst>(InsertPos) || isa<PHINode>(InsertPos))
00050     ++InsertPos;
00051 
00052   Instruction *InstrCall = new CallInst (InstrFn, Args, "", InsertPos);
00053 }
00054 
00055 bool TraceBasicBlocks::runOnModule(Module &M) {
00056   Function *Main = M.getMainFunction();
00057   if (Main == 0) {
00058     std::cerr << "WARNING: cannot insert basic-block trace instrumentation"
00059               << " into a module with no main function!\n";
00060     return false;  // No main, no instrumentation!
00061   }
00062 
00063   unsigned BBNumber = 0;
00064   for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F)
00065     for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
00066       InsertInstrumentationCall (BB, "llvm_trace_basic_block", BBNumber);
00067       ++BBNumber;
00068     }
00069 
00070   // Add the initialization call to main.
00071   InsertProfilingInitCall(Main, "llvm_start_basic_block_tracing");
00072   return true;
00073 }
00074