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must be called in the pass's constructor. This function uses static dependency declarations to recursively initialize the pass's dependencies. Clients that only create passes through the createFooPass() APIs will require no changes. Clients that want to use the CommandLine options for passes will need to manually call the appropriate initialization functions in PassInitialization.h before parsing commandline arguments. I have tested this with all standard configurations of clang and llvm-gcc on Darwin. It is possible that there are problems with the static dependencies that will only be visible with non-standard options. If you encounter any crash in pass registration/creation, please send the testcase to me directly. llvm-svn: 116820
117 lines
4.4 KiB
C++
117 lines
4.4 KiB
C++
//===- EdgeProfiling.cpp - Insert counters for 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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// Note that this implementation is very naive. We insert a counter for *every*
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// edge in the program, instead of using control flow information to prune the
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// number of counters inserted.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "insert-edge-profiling"
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#include "ProfilingUtils.h"
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#include "llvm/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/raw_ostream.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 <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 EdgeProfiler : public ModulePass {
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bool runOnModule(Module &M);
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public:
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static char ID; // Pass identification, replacement for typeid
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EdgeProfiler() : ModulePass(ID) {
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initializeEdgeProfilerPass(*PassRegistry::getPassRegistry());
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}
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virtual const char *getPassName() const {
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return "Edge Profiler";
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}
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};
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}
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char EdgeProfiler::ID = 0;
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INITIALIZE_PASS(EdgeProfiler, "insert-edge-profiling",
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"Insert instrumentation for edge profiling", false, false)
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ModulePass *llvm::createEdgeProfilerPass() { return new EdgeProfiler(); }
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bool EdgeProfiler::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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NumEdges += BB->getTerminator()->getNumSuccessors();
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}
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}
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const Type *ATy = ArrayType::get(Type::getInt32Ty(M.getContext()), 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), "EdgeProfCounters");
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NumEdgesInserted = NumEdges;
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// Instrument all of the edges...
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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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// Create counter for (0,entry) edge.
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IncrementCounterInBlock(&F->getEntryBlock(), i++, Counters);
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for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
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if (BlocksToInstrument.count(BB)) { // Don't instrument inserted blocks
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// Okay, we have to add a counter of each outgoing edge. If the
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// outgoing edge is not critical don't split it, just insert the counter
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// in the source or destination of the edge.
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TerminatorInst *TI = BB->getTerminator();
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for (unsigned s = 0, e = TI->getNumSuccessors(); s != e; ++s) {
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// If the edge is critical, split it.
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SplitCriticalEdge(TI, s, this);
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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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IncrementCounterInBlock(BB, i++, Counters);
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} else {
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// Insert counter at the start of the block
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IncrementCounterInBlock(TI->getSuccessor(s), i++, Counters);
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}
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}
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}
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}
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// Add the initialization call to main.
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InsertProfilingInitCall(Main, "llvm_start_edge_profiling", Counters);
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return true;
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}
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