//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "insert-optimal-edge-profiling"
+#include "llvm/Transforms/Instrumentation.h"
+#include "MaximumSpanningTree.h"
#include "ProfilingUtils.h"
-#include "llvm/Constants.h"
-#include "llvm/Function.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Module.h"
-#include "llvm/Pass.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/ProfileInfo.h"
-#include "llvm/Support/Compiler.h"
+#include "llvm/Analysis/ProfileInfoLoader.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Transforms/Instrumentation.h"
-#include "llvm/ADT/Statistic.h"
-#include "MaximumSpanningTree.h"
-#include <set>
using namespace llvm;
STATISTIC(NumEdgesInserted, "The # of edges inserted.");
namespace {
- class VISIBILITY_HIDDEN OptimalEdgeProfiler : public ModulePass {
+ class OptimalEdgeProfiler : public ModulePass {
bool runOnModule(Module &M);
- ProfileInfo *PI;
public:
static char ID; // Pass identification, replacement for typeid
- OptimalEdgeProfiler() : ModulePass(&ID) {}
+ OptimalEdgeProfiler() : ModulePass(ID) {
+ initializeOptimalEdgeProfilerPass(*PassRegistry::getPassRegistry());
+ }
void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequiredID(ProfileEstimatorPassID);
}
char OptimalEdgeProfiler::ID = 0;
-static RegisterPass<OptimalEdgeProfiler>
-X("insert-optimal-edge-profiling",
- "Insert optimal instrumentation for edge profiling");
+INITIALIZE_PASS_BEGIN(OptimalEdgeProfiler, "insert-optimal-edge-profiling",
+ "Insert optimal instrumentation for edge profiling",
+ false, false)
+INITIALIZE_PASS_DEPENDENCY(ProfileEstimatorPass)
+INITIALIZE_AG_DEPENDENCY(ProfileInfo)
+INITIALIZE_PASS_END(OptimalEdgeProfiler, "insert-optimal-edge-profiling",
+ "Insert optimal instrumentation for edge profiling",
+ false, false)
ModulePass *llvm::createOptimalEdgeProfilerPass() {
return new OptimalEdgeProfiler();
inline static void printEdgeCounter(ProfileInfo::Edge e,
BasicBlock* b,
unsigned i) {
- DEBUG(errs() << "--Edge Counter for " << (e) << " in " \
- << ((b)?(b)->getNameStr():"0") << " (# " << (i) << ")\n");
+ DEBUG(dbgs() << "--Edge Counter for " << (e) << " in " \
+ << ((b)?(b)->getName():"0") << " (# " << (i) << ")\n");
}
bool OptimalEdgeProfiler::runOnModule(Module &M) {
return false; // No main, no instrumentation!
}
- std::set<BasicBlock*> BlocksToInstrument;
+ // NumEdges counts all the edges that may be instrumented. Later on its
+ // decided which edges to actually instrument, to achieve optimal profiling.
+ // For the entry block a virtual edge (0,entry) is reserved, for each block
+ // with no successors an edge (BB,0) is reserved. These edges are necessary
+ // to calculate a truly optimal maximum spanning tree and thus an optimal
+ // instrumentation.
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.
// 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);
if (BB->getTerminator()->getNumSuccessors() == 0) {
// Reserve space for (BB,0) edge.
++NumEdges;
}
}
- const Type *Int32 = Type::getInt32Ty(M.getContext());
- const ArrayType *ATy = ArrayType::get(Int32, NumEdges);
+ // In the profiling output a counter for each edge is reserved, but only few
+ // are used. This is done to be able to read back in the profile without
+ // calulating the maximum spanning tree again, instead each edge counter that
+ // is not used is initialised with -1 to signal that this edge counter has to
+ // be calculated from other edge counters on reading the profile info back
+ // in.
+
+ Type *Int32 = Type::getInt32Ty(M.getContext());
+ ArrayType *ATy = ArrayType::get(Int32, NumEdges);
GlobalVariable *Counters =
new GlobalVariable(M, ATy, false, GlobalValue::InternalLinkage,
Constant::getNullValue(ATy), "OptEdgeProfCounters");
NumEdgesInserted = 0;
std::vector<Constant*> Initializer(NumEdges);
- Constant* zeroc = ConstantInt::get(Int32, 0);
- Constant* minusonec = ConstantInt::get(Int32, ProfileInfo::MissingValue);
+ Constant *Zero = ConstantInt::get(Int32, 0);
+ Constant *Uncounted = ConstantInt::get(Int32, ProfileInfoLoader::Uncounted);
// Instrument all of the edges not in MST...
unsigned i = 0;
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
if (F->isDeclaration()) continue;
- DEBUG(errs()<<"Working on "<<F->getNameStr()<<"\n");
+ DEBUG(dbgs() << "Working on " << F->getName() << "\n");
- PI = &getAnalysisID<ProfileInfo>(ProfileEstimatorPassID,*F);
- MaximumSpanningTree MST = MaximumSpanningTree(&(*F),PI,true);
+ // Calculate a Maximum Spanning Tree with the edge weights determined by
+ // ProfileEstimator. ProfileEstimator also assign weights to the virtual
+ // edges (0,entry) and (BB,0) (for blocks with no successors) and this
+ // edges also participate in the maximum spanning tree calculation.
+ // The third parameter of MaximumSpanningTree() has the effect that not the
+ // actual MST is returned but the edges _not_ in the MST.
+
+ ProfileInfo::EdgeWeights ECs =
+ getAnalysis<ProfileInfo>(*F).getEdgeWeights(F);
+ std::vector<ProfileInfo::EdgeWeight> EdgeVector(ECs.begin(), ECs.end());
+ MaximumSpanningTree<BasicBlock> MST(EdgeVector);
+ std::stable_sort(MST.begin(), MST.end());
+
+ // Check if (0,entry) not in the MST. If not, instrument edge
+ // (IncrementCounterInBlock()) and set the counter initially to zero, if
+ // the edge is in the MST the counter is initialised to -1.
- // Create counter for (0,entry) edge.
BasicBlock *entry = &(F->getEntryBlock());
- ProfileInfo::Edge edge = ProfileInfo::getEdge(0,entry);
- if (std::binary_search(MST.begin(),MST.end(),edge)) {
- printEdgeCounter(edge,entry,i);
- IncrementCounterInBlock(entry, i, Counters); NumEdgesInserted++;
- Initializer[i++] = (zeroc);
+ ProfileInfo::Edge edge = ProfileInfo::getEdge(0, entry);
+ if (!std::binary_search(MST.begin(), MST.end(), edge)) {
+ printEdgeCounter(edge, entry, i);
+ IncrementCounterInBlock(entry, i, Counters); ++NumEdgesInserted;
+ Initializer[i++] = (Zero);
} else{
- Initializer[i++] = (minusonec);
+ Initializer[i++] = (Uncounted);
}
+ // InsertedBlocks contains all blocks that were inserted for splitting an
+ // edge, this blocks do not have to be instrumented.
+ DenseSet<BasicBlock*> InsertedBlocks;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
- if (!BlocksToInstrument.count(BB)) continue; // Don't count new blocks
+ // Check if block was not inserted and thus does not have to be
+ // instrumented.
+ if (InsertedBlocks.count(BB)) continue;
+
// Okay, we have to add a counter of each outgoing edge not in MST. If
// the outgoing edge is not critical don't split it, just insert the
- // counter in the source or destination of the edge.
+ // counter in the source or destination of the edge. Also, if the block
+ // has no successors, the virtual edge (BB,0) is processed.
TerminatorInst *TI = BB->getTerminator();
if (TI->getNumSuccessors() == 0) {
- // Create counter for (BB,0), edge.
- ProfileInfo::Edge edge = ProfileInfo::getEdge(BB,0);
- if (std::binary_search(MST.begin(),MST.end(),edge)) {
- printEdgeCounter(edge,BB,i);
- IncrementCounterInBlock(BB, i, Counters); NumEdgesInserted++;
- Initializer[i++] = (zeroc);
+ ProfileInfo::Edge edge = ProfileInfo::getEdge(BB, 0);
+ if (!std::binary_search(MST.begin(), MST.end(), edge)) {
+ printEdgeCounter(edge, BB, i);
+ IncrementCounterInBlock(BB, i, Counters); ++NumEdgesInserted;
+ Initializer[i++] = (Zero);
} else{
- Initializer[i++] = (minusonec);
+ Initializer[i++] = (Uncounted);
}
}
for (unsigned s = 0, e = TI->getNumSuccessors(); s != e; ++s) {
BasicBlock *Succ = TI->getSuccessor(s);
ProfileInfo::Edge edge = ProfileInfo::getEdge(BB,Succ);
- if (std::binary_search(MST.begin(),MST.end(),edge)) {
+ if (!std::binary_search(MST.begin(), MST.end(), edge)) {
// If the edge is critical, split it.
- SplitCriticalEdge(TI,s,this);
+ bool wasInserted = SplitCriticalEdge(TI, s, this);
Succ = TI->getSuccessor(s);
+ if (wasInserted)
+ InsertedBlocks.insert(Succ);
- // Okay, we are guaranteed that the edge is no longer critical. If we
- // only have a single successor, insert the counter in this block,
+ // 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
- printEdgeCounter(edge,BB,i);
- IncrementCounterInBlock(BB, i, Counters); NumEdgesInserted++;
+ printEdgeCounter(edge, BB, i);
+ IncrementCounterInBlock(BB, i, Counters); ++NumEdgesInserted;
} else {
// Insert counter at the start of the block
- printEdgeCounter(edge,Succ,i);
- IncrementCounterInBlock(Succ, i, Counters); NumEdgesInserted++;
+ printEdgeCounter(edge, Succ, i);
+ IncrementCounterInBlock(Succ, i, Counters); ++NumEdgesInserted;
}
- Initializer[i++] = (zeroc);
+ Initializer[i++] = (Zero);
} else {
- Initializer[i++] = (minusonec);
+ Initializer[i++] = (Uncounted);
}
}
}
}
- // check if indeed all counters have been used
- assert(i==NumEdges && "the number of edges in counting array is wrong");
+ // Check if the number of edges counted at first was the number of edges we
+ // considered for instrumentation.
+ assert(i == NumEdges && "the number of edges in counting array is wrong");
- // assign initialiser to array
+ // Assign the now completely defined initialiser to the array.
Constant *init = ConstantArray::get(ATy, Initializer);
Counters->setInitializer(init);
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