better c99 struct handling

[oota-llvm.git] / lib / Analysis / ProfileInfo.cpp

diff --git a/lib/Analysis/ProfileInfo.cpp b/lib/Analysis/ProfileInfo.cpp
index 24a26c872131edcc96c306ad6875dc17785cab46..fa3af80044fa66f1cc4eebb13a00350267dbe018 100644 (file)
--- a/lib/Analysis/ProfileInfo.cpp
+++ b/lib/Analysis/ProfileInfo.cpp
@@ -1,10 +1,10 @@
 //===- ProfileInfo.cpp - Profile Info Interface ---------------------------===//
-// 
+//
 //                     The LLVM Compiler Infrastructure
 //
 // This file was developed by the LLVM research group and is distributed under
 // the University of Illinois Open Source License. See LICENSE.TXT for details.
-// 
+//
 //===----------------------------------------------------------------------===//
 //
 // This file implements the abstract ProfileInfo interface, and the default
@@ -12,31 +12,84 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Analysis/Passes.h"
 #include "llvm/Analysis/ProfileInfo.h"
 #include "llvm/Pass.h"
+#include "llvm/Support/CFG.h"
+#include <set>
 using namespace llvm;
 
-// Register the AliasAnalysis interface, providing a nice name to refer to.
+// Register the ProfileInfo interface, providing a nice name to refer to.
 namespace {
   RegisterAnalysisGroup<ProfileInfo> Z("Profile Information");
 }
 
 ProfileInfo::~ProfileInfo() {}
 
+unsigned ProfileInfo::getExecutionCount(BasicBlock *BB) const {
+  pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
+
+  // Are there zero predecessors of this block?
+  if (PI == PE) {
+    // If this is the entry block, look for the Null -> Entry edge.
+    if (BB == &BB->getParent()->front())
+      return getEdgeWeight(0, BB);
+    else
+      return 0;   // Otherwise, this is a dead block.
+  }
+
+  // Otherwise, if there are predecessors, the execution count of this block is
+  // the sum of the edge frequencies from the incoming edges.  Note that if
+  // there are multiple edges from a predecessor to this block that we don't
+  // want to count its weight multiple times.  For this reason, we keep track of
+  // the predecessors we've seen and only count them if we haven't run into them
+  // yet.
+  //
+  // We don't want to create an std::set unless we are dealing with a block that
+  // has a LARGE number of in-edges.  Handle the common case of having only a
+  // few in-edges with special code.
+  //
+  BasicBlock *FirstPred = *PI;
+  unsigned Count = getEdgeWeight(FirstPred, BB);
+  ++PI;
+  if (PI == PE) return Count;   // Quick exit for single predecessor blocks
+
+  BasicBlock *SecondPred = *PI;
+  if (SecondPred != FirstPred) Count += getEdgeWeight(SecondPred, BB);
+  ++PI;
+  if (PI == PE) return Count;   // Quick exit for two predecessor blocks
+
+  BasicBlock *ThirdPred = *PI;
+  if (ThirdPred != FirstPred && ThirdPred != SecondPred)
+    Count += getEdgeWeight(ThirdPred, BB);
+  ++PI;
+  if (PI == PE) return Count;   // Quick exit for three predecessor blocks
+
+  std::set<BasicBlock*> ProcessedPreds;
+  ProcessedPreds.insert(FirstPred);
+  ProcessedPreds.insert(SecondPred);
+  ProcessedPreds.insert(ThirdPred);
+  for (; PI != PE; ++PI)
+    if (ProcessedPreds.insert(*PI).second)
+      Count += getEdgeWeight(*PI, BB);
+  return Count;
+}
+
+
 
 //===----------------------------------------------------------------------===//
 //  NoProfile ProfileInfo implementation
 //
 
 namespace {
-  struct NoProfileInfo : public ImmutablePass, public ProfileInfo {
-    unsigned getExecutionCount(BasicBlock *BB) { return 0; }
-  };
- 
+  struct NoProfileInfo : public ImmutablePass, public ProfileInfo {};
+
   // Register this pass...
   RegisterOpt<NoProfileInfo>
   X("no-profile", "No Profile Information");
 
-  // Declare that we implement the AliasAnalysis interface
+  // Declare that we implement the ProfileInfo interface
   RegisterAnalysisGroup<ProfileInfo, NoProfileInfo, true> Y;
 }  // End of anonymous namespace
+
+ImmutablePass *llvm::createNoProfileInfoPass() { return new NoProfileInfo(); }