OptimalEdgeProfiling: Creation of profiles.

This adds the instrumentation and runtime part of OptimalEdgeProfiling.

llvm-svn: 80712

include/llvm/Analysis/ProfileInfoTypes.h

@@ -22,7 +22,8 @@ enum ProfilingType {
   BlockInfo     = 3,   /* Block profiling information     */
   EdgeInfo      = 4,   /* Edge profiling information      */
   PathInfo      = 5,   /* Path profiling information      */
-  BBTraceInfo   = 6    /* Basic block trace information   */
+  BBTraceInfo   = 6,   /* Basic block trace information   */
+  OptEdgeInfo   = 7    /* Edge profiling information, optimal version */
 };
 
 #endif /* LLVM_ANALYSIS_PROFILEINFOTYPES_H */

lib/Transforms/Instrumentation/CMakeLists.txt

@@ -2,6 +2,7 @@ add_llvm_library(LLVMInstrumentation
   BlockProfiling.cpp
   EdgeProfiling.cpp
   MaximumSpanningTree.cpp
+  OptimalEdgeProfiling.cpp
   ProfilingUtils.cpp
   RSProfiling.cpp
   )

lib/Transforms/Instrumentation/OptimalEdgeProfiling.cpp

@@ -0,0 +1,186 @@
+//===- OptimalEdgeProfiling.cpp - Insert counters for opt. 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.
+//
+//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "insert-optimal-edge-profiling"
+#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/Analysis/Passes.h"
+#include "llvm/Analysis/ProfileInfo.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.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 {
+    bool runOnModule(Module &M);
+    ProfileInfo *PI;
+  public:
+    static char ID; // Pass identification, replacement for typeid
+    OptimalEdgeProfiler() : ModulePass(&ID) {}
+
+    void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.addRequiredID(ProfileEstimatorPassID);
+      AU.addRequired<ProfileInfo>();
+    }
+
+    virtual const char *getPassName() const {
+      return "Optimal Edge Profiler";
+    }
+  };
+}
+
+char OptimalEdgeProfiler::ID = 0;
+static RegisterPass<OptimalEdgeProfiler>
+X("insert-optimal-edge-profiling", 
+  "Insert optimal instrumentation for edge profiling");
+
+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");
+}
+
+bool OptimalEdgeProfiler::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);
+      if (BB->getTerminator()->getNumSuccessors() == 0) {
+        // Reserve space for (BB,0) edge.
+        ++NumEdges;
+      } else {
+        NumEdges += BB->getTerminator()->getNumSuccessors();
+      }
+    }
+  }
+
+  const Type *Int32 = Type::getInt32Ty(M.getContext());
+  const 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);
+
+  // 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");
+
+    PI = &getAnalysisID<ProfileInfo>(ProfileEstimatorPassID,*F);
+    MaximumSpanningTree MST = MaximumSpanningTree(&(*F),PI,true);
+
+    // 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);
+    } else{
+      Initializer[i++] = (minusonec);
+    }
+
+    for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
+      if (!BlocksToInstrument.count(BB)) continue; // Don't count new blocks
+      // 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.
+      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);
+        } else{
+          Initializer[i++] = (minusonec);
+        }
+      }
+      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 the edge is critical, split it.
+          SplitCriticalEdge(TI,s,this);
+          Succ = TI->getSuccessor(s);
+
+          // 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++;
+          } else {
+            // Insert counter at the start of the block
+            printEdgeCounter(edge,Succ,i);
+            IncrementCounterInBlock(Succ, i, Counters); NumEdgesInserted++;
+          }
+          Initializer[i++] = (zeroc);
+        } else {
+          Initializer[i++] = (minusonec);
+        }
+      }
+    }
+  }
+
+  // check if indeed all counters have been used
+  assert(i==NumEdges && "the number of edges in counting array is wrong");
+
+  // assign initialiser to array
+  Constant *init = ConstantArray::get(ATy, Initializer);
+  Counters->setInitializer(init);
+
+  // Add the initialization call to main.
+  InsertProfilingInitCall(Main, "llvm_start_opt_edge_profiling", Counters);
+  return true;
+}
+

runtime/libprofile/OptimalEdgeProfiling.c

@@ -0,0 +1,45 @@
+/*===-- OptimalEdgeProfiling.c - Support library for opt. edge profiling --===*\
+|*
+|*                     The LLVM Compiler Infrastructure
+|*
+|* This file is distributed under the University of Illinois Open Source      
+|* License. See LICENSE.TXT for details.                                      
+|* 
+|*===----------------------------------------------------------------------===*|
+|* 
+|* This file implements the call back routines for the edge profiling
+|* instrumentation pass.  This should be used with the
+|* -insert-opt-edge-profiling LLVM pass.
+|*
+\*===----------------------------------------------------------------------===*/
+
+#include "Profiling.h"
+#include <stdlib.h>
+
+static unsigned *ArrayStart;
+static unsigned NumElements;
+
+/* OptEdgeProfAtExitHandler - When the program exits, just write out the
+ * profiling data.
+ */
+static void OptEdgeProfAtExitHandler() {
+  /* Note that, although the array has a counter for each edge, not all
+   * counters are updated, the ones that are not used are initialised with -1.
+   * When loading this information the counters with value -1 have to be
+   * recalculated, it is guranteed that this is possible.
+   */
+  write_profiling_data(OptEdgeInfo, ArrayStart, NumElements);
+}
+
+
+/* llvm_start_opt_edge_profiling - This is the main entry point of the edge
+ * profiling library.  It is responsible for setting up the atexit handler.
+ */
+int llvm_start_opt_edge_profiling(int argc, const char **argv,
+                                  unsigned *arrayStart, unsigned numElements) {
+  int Ret = save_arguments(argc, argv);
+  ArrayStart = arrayStart;
+  NumElements = numElements;
+  atexit(OptEdgeProfAtExitHandler);
+  return Ret;
+}

runtime/libprofile/exported_symbols.lst

@@ -2,5 +2,6 @@
 llvm_start_func_profiling
 llvm_start_block_profiling
 llvm_start_edge_profiling
+llvm_start_opt_edge_profiling
 llvm_start_basic_block_tracing
 llvm_trace_basic_block