mirror of
https://github.com/c64scene-ar/llvm-6502.git
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187 lines
6.8 KiB
C++
187 lines
6.8 KiB
C++
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//===- OptimalEdgeProfiling.cpp - Insert counters for opt. edge profiling -===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass instruments the specified program with counters for edge profiling.
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// Edge profiling can give a reasonable approximation of the hot paths through a
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// program, and is used for a wide variety of program transformations.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "insert-optimal-edge-profiling"
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#include "ProfilingUtils.h"
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#include "llvm/Constants.h"
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#include "llvm/Function.h"
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#include "llvm/LLVMContext.h"
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#include "llvm/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Analysis/Passes.h"
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#include "llvm/Analysis/ProfileInfo.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Instrumentation.h"
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#include "llvm/ADT/Statistic.h"
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#include "MaximumSpanningTree.h"
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#include <set>
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using namespace llvm;
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STATISTIC(NumEdgesInserted, "The # of edges inserted.");
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namespace {
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class VISIBILITY_HIDDEN OptimalEdgeProfiler : public ModulePass {
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bool runOnModule(Module &M);
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ProfileInfo *PI;
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public:
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static char ID; // Pass identification, replacement for typeid
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OptimalEdgeProfiler() : ModulePass(&ID) {}
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void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequiredID(ProfileEstimatorPassID);
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AU.addRequired<ProfileInfo>();
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}
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virtual const char *getPassName() const {
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return "Optimal Edge Profiler";
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}
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};
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}
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char OptimalEdgeProfiler::ID = 0;
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static RegisterPass<OptimalEdgeProfiler>
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X("insert-optimal-edge-profiling",
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"Insert optimal instrumentation for edge profiling");
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ModulePass *llvm::createOptimalEdgeProfilerPass() {
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return new OptimalEdgeProfiler();
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}
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inline static void printEdgeCounter(ProfileInfo::Edge e,
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BasicBlock* b,
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unsigned i) {
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DEBUG(errs() << "--Edge Counter for " << (e) << " in " \
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<< ((b)?(b)->getNameStr():"0") << " (# " << (i) << ")\n");
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}
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bool OptimalEdgeProfiler::runOnModule(Module &M) {
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Function *Main = M.getFunction("main");
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if (Main == 0) {
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errs() << "WARNING: cannot insert edge profiling into a module"
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<< " with no main function!\n";
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return false; // No main, no instrumentation!
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}
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std::set<BasicBlock*> BlocksToInstrument;
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unsigned NumEdges = 0;
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for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
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if (F->isDeclaration()) continue;
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// Reserve space for (0,entry) edge.
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++NumEdges;
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for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
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// Keep track of which blocks need to be instrumented. We don't want to
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// instrument blocks that are added as the result of breaking critical
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// edges!
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BlocksToInstrument.insert(BB);
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if (BB->getTerminator()->getNumSuccessors() == 0) {
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// Reserve space for (BB,0) edge.
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++NumEdges;
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} else {
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NumEdges += BB->getTerminator()->getNumSuccessors();
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}
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}
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}
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const Type *Int32 = Type::getInt32Ty(M.getContext());
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const ArrayType *ATy = ArrayType::get(Int32, NumEdges);
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GlobalVariable *Counters =
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new GlobalVariable(M, ATy, false, GlobalValue::InternalLinkage,
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Constant::getNullValue(ATy), "OptEdgeProfCounters");
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NumEdgesInserted = 0;
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std::vector<Constant*> Initializer(NumEdges);
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Constant* zeroc = ConstantInt::get(Int32, 0);
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Constant* minusonec = ConstantInt::get(Int32, ProfileInfo::MissingValue);
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// Instrument all of the edges not in MST...
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unsigned i = 0;
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for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
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if (F->isDeclaration()) continue;
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DEBUG(errs()<<"Working on "<<F->getNameStr()<<"\n");
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PI = &getAnalysisID<ProfileInfo>(ProfileEstimatorPassID,*F);
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MaximumSpanningTree MST = MaximumSpanningTree(&(*F),PI,true);
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// Create counter for (0,entry) edge.
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BasicBlock *entry = &(F->getEntryBlock());
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ProfileInfo::Edge edge = ProfileInfo::getEdge(0,entry);
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if (std::binary_search(MST.begin(),MST.end(),edge)) {
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printEdgeCounter(edge,entry,i);
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IncrementCounterInBlock(entry, i, Counters); NumEdgesInserted++;
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Initializer[i++] = (zeroc);
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} else{
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Initializer[i++] = (minusonec);
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}
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for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
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if (!BlocksToInstrument.count(BB)) continue; // Don't count new blocks
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// Okay, we have to add a counter of each outgoing edge not in MST. If
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// the outgoing edge is not critical don't split it, just insert the
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// counter in the source or destination of the edge.
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TerminatorInst *TI = BB->getTerminator();
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if (TI->getNumSuccessors() == 0) {
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// Create counter for (BB,0), edge.
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ProfileInfo::Edge edge = ProfileInfo::getEdge(BB,0);
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if (std::binary_search(MST.begin(),MST.end(),edge)) {
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printEdgeCounter(edge,BB,i);
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IncrementCounterInBlock(BB, i, Counters); NumEdgesInserted++;
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Initializer[i++] = (zeroc);
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} else{
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Initializer[i++] = (minusonec);
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}
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}
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for (unsigned s = 0, e = TI->getNumSuccessors(); s != e; ++s) {
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BasicBlock *Succ = TI->getSuccessor(s);
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ProfileInfo::Edge edge = ProfileInfo::getEdge(BB,Succ);
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if (std::binary_search(MST.begin(),MST.end(),edge)) {
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// If the edge is critical, split it.
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SplitCriticalEdge(TI,s,this);
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Succ = TI->getSuccessor(s);
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// Okay, we are guaranteed that the edge is no longer critical. If we
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// only have a single successor, insert the counter in this block,
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// otherwise insert it in the successor block.
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if (TI->getNumSuccessors() == 1) {
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// Insert counter at the start of the block
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printEdgeCounter(edge,BB,i);
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IncrementCounterInBlock(BB, i, Counters); NumEdgesInserted++;
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} else {
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// Insert counter at the start of the block
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printEdgeCounter(edge,Succ,i);
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IncrementCounterInBlock(Succ, i, Counters); NumEdgesInserted++;
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}
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Initializer[i++] = (zeroc);
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} else {
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Initializer[i++] = (minusonec);
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}
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}
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}
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}
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// check if indeed all counters have been used
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assert(i==NumEdges && "the number of edges in counting array is wrong");
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// assign initialiser to array
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Constant *init = ConstantArray::get(ATy, Initializer);
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Counters->setInitializer(init);
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// Add the initialization call to main.
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InsertProfilingInitCall(Main, "llvm_start_opt_edge_profiling", Counters);
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return true;
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}
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