LLVM API Documentation

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/Transforms/Instrumentation.h"
00022 #include "llvm/Instructions.h"
00023 #include "ProfilingUtils.h"
00024 #include "llvm/Support/Debug.h"
00025 #include <set>
00026 #include <iostream>
00027 using namespace llvm;
00028 
00029 namespace {
00030   class TraceBasicBlocks : public ModulePass {
00031     bool runOnModule(Module &M);
00032   };
00033 
00034   RegisterOpt<TraceBasicBlocks> X("trace-basic-blocks",
00035                               "Insert instrumentation for basic block tracing");
00036 }
00037 
00038 ModulePass *llvm::createTraceBasicBlockPass()
00039 {
00040   return new TraceBasicBlocks();
00041 }
00042 
00043 static void InsertInstrumentationCall (BasicBlock *BB,
00044                                        const std::string FnName,
00045                                        unsigned BBNumber) {
00046   DEBUG (std::cerr << "InsertInstrumentationCall (\"" << BB->getName ()
00047                    << "\", \"" << FnName << "\", " << BBNumber << ")\n");
00048   Module &M = *BB->getParent ()->getParent ();
00049   Function *InstrFn = M.getOrInsertFunction (FnName, Type::VoidTy,
00050                                              Type::UIntTy, (Type *)0);
00051   std::vector<Value*> Args (1);
00052   Args[0] = ConstantUInt::get (Type::UIntTy, BBNumber);
00053 
00054   // Insert the call after any alloca or PHI instructions...
00055   BasicBlock::iterator InsertPos = BB->begin();
00056   while (isa<AllocaInst>(InsertPos) || isa<PHINode>(InsertPos))
00057     ++InsertPos;
00058 
00059   Instruction *InstrCall = new CallInst (InstrFn, Args, "", InsertPos);
00060 }
00061 
00062 bool TraceBasicBlocks::runOnModule(Module &M) {
00063   Function *Main = M.getMainFunction();
00064   if (Main == 0) {
00065     std::cerr << "WARNING: cannot insert basic-block trace instrumentation"
00066               << " into a module with no main function!\n";
00067     return false;  // No main, no instrumentation!
00068   }
00069 
00070   unsigned BBNumber = 0;
00071   for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F)
00072     for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
00073       InsertInstrumentationCall (BB, "llvm_trace_basic_block", BBNumber);
00074       ++BBNumber;
00075     }
00076 
00077   // Add the initialization call to main.
00078   InsertProfilingInitCall(Main, "llvm_start_basic_block_tracing");
00079   return true;
00080 }
00081