[llvm] r256039 - Use getEdgeProbability() instead of getEdgeWeight() in BFI and remove getEdgeWeight() interfaces from MBPI.

[Cong Hou via llvm-commits]

Author: conghou
Date: Fri Dec 18 15:53:24 2015
New Revision: 256039

URL: http://llvm.org/viewvc/llvm-project?rev=256039&view=rev
Log:
Use getEdgeProbability() instead of getEdgeWeight() in BFI and remove getEdgeWeight() interfaces from MBPI.

This patch removes all getEdgeWeight() interfaces from CodeGen directory. As
getEdgeProbability() is a little more expensive than getEdgeWeight(), I will
compose a patch soon in which BPI only stores probabilities instead of edge
weights so that getEdgeProbability() will have O(1) time.


Differential revision: http://reviews.llvm.org/D15489



Modified:
    llvm/trunk/include/llvm/Analysis/BlockFrequencyInfoImpl.h
    llvm/trunk/include/llvm/CodeGen/MachineBranchProbabilityInfo.h
    llvm/trunk/lib/CodeGen/MachineBranchProbabilityInfo.cpp
    llvm/trunk/test/Analysis/BlockFrequencyInfo/bad_input.ll

Modified: llvm/trunk/include/llvm/Analysis/BlockFrequencyInfoImpl.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/BlockFrequencyInfoImpl.h?rev=256039&r1=256038&r2=256039&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/BlockFrequencyInfoImpl.h (original)
+++ llvm/trunk/include/llvm/Analysis/BlockFrequencyInfoImpl.h Fri Dec 18 15:53:24 2015
@@ -1173,6 +1173,13 @@ void BlockFrequencyInfoImpl<BT>::compute
   updateLoopWithIrreducible(*OuterLoop);
 }
 
+namespace {
+// A helper function that converts a branch probability into weight.
+inline uint32_t getWeightFromBranchProb(const BranchProbability Prob) {
+  return Prob.getNumerator();
+}
+} // namespace
+
 template <class BT>
 bool
 BlockFrequencyInfoImpl<BT>::propagateMassToSuccessors(LoopData *OuterLoop,
@@ -1189,10 +1196,8 @@ BlockFrequencyInfoImpl<BT>::propagateMas
     const BlockT *BB = getBlock(Node);
     for (auto SI = Successor::child_begin(BB), SE = Successor::child_end(BB);
          SI != SE; ++SI)
-      // Do not dereference SI, or getEdgeWeight() is linear in the number of
-      // successors.
       if (!addToDist(Dist, OuterLoop, Node, getNode(*SI),
-                     BPI->getEdgeWeight(BB, SI)))
+                     getWeightFromBranchProb(BPI->getEdgeProbability(BB, SI))))
         // Irreducible backedge.
         return false;
   }

Modified: llvm/trunk/include/llvm/CodeGen/MachineBranchProbabilityInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/MachineBranchProbabilityInfo.h?rev=256039&r1=256038&r2=256039&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/MachineBranchProbabilityInfo.h (original)
+++ llvm/trunk/include/llvm/CodeGen/MachineBranchProbabilityInfo.h Fri Dec 18 15:53:24 2015
@@ -45,16 +45,6 @@ public:
     AU.setPreservesAll();
   }
 
-  // Return edge weight. If we don't have any informations about it - return
-  // DEFAULT_WEIGHT.
-  uint32_t getEdgeWeight(const MachineBasicBlock *Src,
-                         const MachineBasicBlock *Dst) const;
-
-  // Same thing, but using a const_succ_iterator from Src. This is faster when
-  // the iterator is already available.
-  uint32_t getEdgeWeight(const MachineBasicBlock *Src,
-                         MachineBasicBlock::const_succ_iterator Dst) const;
-
   // Return edge probability.
   BranchProbability getEdgeProbability(const MachineBasicBlock *Src,
                                        const MachineBasicBlock *Dst) const;

Modified: llvm/trunk/lib/CodeGen/MachineBranchProbabilityInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineBranchProbabilityInfo.cpp?rev=256039&r1=256038&r2=256039&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineBranchProbabilityInfo.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineBranchProbabilityInfo.cpp Fri Dec 18 15:53:24 2015
@@ -28,19 +28,6 @@ char MachineBranchProbabilityInfo::ID =
 
 void MachineBranchProbabilityInfo::anchor() { }
 
-uint32_t MachineBranchProbabilityInfo::getEdgeWeight(
-    const MachineBasicBlock *Src,
-    MachineBasicBlock::const_succ_iterator Dst) const {
-  return Src->getSuccProbability(Dst).getNumerator();
-}
-
-uint32_t MachineBranchProbabilityInfo::getEdgeWeight(
-    const MachineBasicBlock *Src, const MachineBasicBlock *Dst) const {
-  // This is a linear search. Try to use the const_succ_iterator version when
-  // possible.
-  return getEdgeWeight(Src, std::find(Src->succ_begin(), Src->succ_end(), Dst));
-}
-
 BranchProbability MachineBranchProbabilityInfo::getEdgeProbability(
     const MachineBasicBlock *Src,
     MachineBasicBlock::const_succ_iterator Dst) const {

Modified: llvm/trunk/test/Analysis/BlockFrequencyInfo/bad_input.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/BlockFrequencyInfo/bad_input.ll?rev=256039&r1=256038&r2=256039&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/BlockFrequencyInfo/bad_input.ll (original)
+++ llvm/trunk/test/Analysis/BlockFrequencyInfo/bad_input.ll Fri Dec 18 15:53:24 2015
@@ -9,8 +9,8 @@ define void @branch_weight_0(i32 %a) {
 entry:
   br label %for.body
 
-; Check that we get 1,4 instead of 0,3.
-; CHECK-NEXT: for.body: float = 4.0,
+; Check that we get 1 and a huge frequency instead of 0,3.
+; CHECK-NEXT: for.body: float = 2147483647.8,
 for.body:
   %i = phi i32 [ 0, %entry ], [ %inc, %for.body ]
   call void @g(i32 %i)