Reapply "blockfreq: Rewrite BlockFrequencyInfoImpl" (llvm-mirror#2)

This reverts commit r206628, reapplying r206622 (and r206626).

Two tests are failing only on buildbots [1][2]: i.e., I can't reproduce
on Darwin, and Chandler can't reproduce on Linux.  Asan and valgrind
don't tell us anything, but we're hoping the msan bot will catch it.

So, I'm applying this again to get more feedback from the bots.  I'll
leave it in long enough to trigger builds in at least the sanitizer
buildbots (it was failing for reasons unrelated to my commit last time
it was in), and hopefully a few others.... and then I expect to revert a
third time.

[1]: http://bb.pgr.jp/builders/ninja-x64-msvc-RA-centos6/builds/1816
[2]: http://llvm-amd64.freebsd.your.org/b/builders/clang-i386-freebsd/builds/18445

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206666 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/BlockFrequencyInfo.cpp

@@ -11,6 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#define DEBUG_TYPE "block-freq"
 #include "llvm/Analysis/BlockFrequencyInfo.h"
 #include "llvm/Analysis/BlockFrequencyInfoImpl.h"
 #include "llvm/Analysis/BranchProbabilityInfo.h"
@@ -106,6 +107,7 @@ struct DOTGraphTraits<BlockFrequencyInfo*> : public DefaultDOTGraphTraits {
 INITIALIZE_PASS_BEGIN(BlockFrequencyInfo, "block-freq",
                       "Block Frequency Analysis", true, true)
 INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfo)
+INITIALIZE_PASS_DEPENDENCY(LoopInfo)
 INITIALIZE_PASS_END(BlockFrequencyInfo, "block-freq",
                     "Block Frequency Analysis", true, true)
 
@@ -120,14 +122,16 @@ BlockFrequencyInfo::~BlockFrequencyInfo() {}
 
 void BlockFrequencyInfo::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addRequired<BranchProbabilityInfo>();
+  AU.addRequired<LoopInfo>();
   AU.setPreservesAll();
 }
 
 bool BlockFrequencyInfo::runOnFunction(Function &F) {
   BranchProbabilityInfo &BPI = getAnalysis<BranchProbabilityInfo>();
+  LoopInfo &LI = getAnalysis<LoopInfo>();
   if (!BFI)
     BFI.reset(new ImplType);
-  BFI->doFunction(&F, &BPI);
+  BFI->doFunction(&F, &BPI, &LI);
 #ifndef NDEBUG
   if (ViewBlockFreqPropagationDAG != GVDT_None)
     view();
@@ -158,7 +162,7 @@ void BlockFrequencyInfo::view() const {
 }
 
 const Function *BlockFrequencyInfo::getFunction() const {
-  return BFI ? BFI->Fn : nullptr;
+  return BFI ? BFI->getFunction() : nullptr;
 }
 
 raw_ostream &BlockFrequencyInfo::