diff options
Diffstat (limited to 'contrib/llvm/lib/Transforms/Instrumentation/EdgeProfiling.cpp')
-rw-r--r-- | contrib/llvm/lib/Transforms/Instrumentation/EdgeProfiling.cpp | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Transforms/Instrumentation/EdgeProfiling.cpp b/contrib/llvm/lib/Transforms/Instrumentation/EdgeProfiling.cpp new file mode 100644 index 0000000..9ae3786 --- /dev/null +++ b/contrib/llvm/lib/Transforms/Instrumentation/EdgeProfiling.cpp @@ -0,0 +1,114 @@ +//===- EdgeProfiling.cpp - Insert counters for edge profiling -------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This pass instruments the specified program with counters for edge profiling. +// Edge profiling can give a reasonable approximation of the hot paths through a +// program, and is used for a wide variety of program transformations. +// +// Note that this implementation is very naive. We insert a counter for *every* +// edge in the program, instead of using control flow information to prune the +// number of counters inserted. +// +//===----------------------------------------------------------------------===// +#define DEBUG_TYPE "insert-edge-profiling" +#include "ProfilingUtils.h" +#include "llvm/Module.h" +#include "llvm/Pass.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Transforms/Utils/BasicBlockUtils.h" +#include "llvm/Transforms/Instrumentation.h" +#include "llvm/ADT/Statistic.h" +#include <set> +using namespace llvm; + +STATISTIC(NumEdgesInserted, "The # of edges inserted."); + +namespace { + class EdgeProfiler : public ModulePass { + bool runOnModule(Module &M); + public: + static char ID; // Pass identification, replacement for typeid + EdgeProfiler() : ModulePass(&ID) {} + + virtual const char *getPassName() const { + return "Edge Profiler"; + } + }; +} + +char EdgeProfiler::ID = 0; +static RegisterPass<EdgeProfiler> +X("insert-edge-profiling", "Insert instrumentation for edge profiling"); + +ModulePass *llvm::createEdgeProfilerPass() { return new EdgeProfiler(); } + +bool EdgeProfiler::runOnModule(Module &M) { + Function *Main = M.getFunction("main"); + if (Main == 0) { + errs() << "WARNING: cannot insert edge profiling into a module" + << " with no main function!\n"; + return false; // No main, no instrumentation! + } + + std::set<BasicBlock*> BlocksToInstrument; + unsigned NumEdges = 0; + for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) { + if (F->isDeclaration()) continue; + // Reserve space for (0,entry) edge. + ++NumEdges; + for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) { + // Keep track of which blocks need to be instrumented. We don't want to + // instrument blocks that are added as the result of breaking critical + // edges! + BlocksToInstrument.insert(BB); + NumEdges += BB->getTerminator()->getNumSuccessors(); + } + } + + const Type *ATy = ArrayType::get(Type::getInt32Ty(M.getContext()), NumEdges); + GlobalVariable *Counters = + new GlobalVariable(M, ATy, false, GlobalValue::InternalLinkage, + Constant::getNullValue(ATy), "EdgeProfCounters"); + NumEdgesInserted = NumEdges; + + // Instrument all of the edges... + unsigned i = 0; + for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) { + if (F->isDeclaration()) continue; + // Create counter for (0,entry) edge. + IncrementCounterInBlock(&F->getEntryBlock(), i++, Counters); + for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) + if (BlocksToInstrument.count(BB)) { // Don't instrument inserted blocks + // Okay, we have to add a counter of each outgoing edge. If the + // outgoing edge is not critical don't split it, just insert the counter + // in the source or destination of the edge. + TerminatorInst *TI = BB->getTerminator(); + for (unsigned s = 0, e = TI->getNumSuccessors(); s != e; ++s) { + // If the edge is critical, split it. + SplitCriticalEdge(TI, s, this); + + // Okay, we are guaranteed that the edge is no longer critical. If we + // only have a single successor, insert the counter in this block, + // otherwise insert it in the successor block. + if (TI->getNumSuccessors() == 1) { + // Insert counter at the start of the block + IncrementCounterInBlock(BB, i++, Counters); + } else { + // Insert counter at the start of the block + IncrementCounterInBlock(TI->getSuccessor(s), i++, Counters); + } + } + } + } + + // Add the initialization call to main. + InsertProfilingInitCall(Main, "llvm_start_edge_profiling", Counters); + return true; +} + |