X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FMachineBranchProbabilityInfo.cpp;h=447921147f03567db30ebf73b5d3575bb59f6773;hb=e3d0e86919730784faaddcb5d9b0257c39b0804b;hp=0037d525151226ee9d3accfa14f8434deeefebd5;hpb=2770c141856eefda6a192622bf5fd5b06bef4963;p=oota-llvm.git

diff --git a/lib/CodeGen/MachineBranchProbabilityInfo.cpp b/lib/CodeGen/MachineBranchProbabilityInfo.cpp
index 0037d525151..447921147f0 100644
--- a/lib/CodeGen/MachineBranchProbabilityInfo.cpp
+++ b/lib/CodeGen/MachineBranchProbabilityInfo.cpp
@@ -26,8 +26,10 @@ INITIALIZE_PASS_END(MachineBranchProbabilityInfo, "machine-branch-prob",
 
 char MachineBranchProbabilityInfo::ID = 0;
 
+void MachineBranchProbabilityInfo::anchor() { }
+
 uint32_t MachineBranchProbabilityInfo::
-getSumForBlock(MachineBasicBlock *MBB, uint32_t &Scale) const {
+getSumForBlock(const MachineBasicBlock *MBB, uint32_t &Scale) const {
   // First we compute the sum with 64-bits of precision, ensuring that cannot
   // overflow by bounding the number of weights considered. Hopefully no one
   // actually needs 2^32 successors.
@@ -36,7 +38,7 @@ getSumForBlock(MachineBasicBlock *MBB, uint32_t &Scale) const {
   Scale = 1;
   for (MachineBasicBlock::const_succ_iterator I = MBB->succ_begin(),
        E = MBB->succ_end(); I != E; ++I) {
-    uint32_t Weight = getEdgeWeight(MBB, *I);
+    uint32_t Weight = getEdgeWeight(MBB, I);
     Sum += Weight;
   }
 
@@ -51,22 +53,30 @@ getSumForBlock(MachineBasicBlock *MBB, uint32_t &Scale) const {
   Sum = 0;
   for (MachineBasicBlock::const_succ_iterator I = MBB->succ_begin(),
        E = MBB->succ_end(); I != E; ++I) {
-    uint32_t Weight = getEdgeWeight(MBB, *I);
+    uint32_t Weight = getEdgeWeight(MBB, I);
     Sum += Weight / Scale;
   }
   assert(Sum <= UINT32_MAX);
   return Sum;
 }
 
-uint32_t
-MachineBranchProbabilityInfo::getEdgeWeight(MachineBasicBlock *Src,
-                                            MachineBasicBlock *Dst) const {
+uint32_t MachineBranchProbabilityInfo::
+getEdgeWeight(const MachineBasicBlock *Src,
+              MachineBasicBlock::const_succ_iterator Dst) const {
   uint32_t Weight = Src->getSuccWeight(Dst);
   if (!Weight)
     return DEFAULT_WEIGHT;
   return Weight;
 }
 
+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));
+}
+
 bool MachineBranchProbabilityInfo::isEdgeHot(MachineBasicBlock *Src,
                                              MachineBasicBlock *Dst) const {
   // Hot probability is at least 4/5 = 80%
@@ -76,26 +86,18 @@ bool MachineBranchProbabilityInfo::isEdgeHot(MachineBasicBlock *Src,
 
 MachineBasicBlock *
 MachineBranchProbabilityInfo::getHotSucc(MachineBasicBlock *MBB) const {
-  uint32_t Sum = 0;
   uint32_t MaxWeight = 0;
   MachineBasicBlock *MaxSucc = 0;
-
   for (MachineBasicBlock::const_succ_iterator I = MBB->succ_begin(),
        E = MBB->succ_end(); I != E; ++I) {
-    MachineBasicBlock *Succ = *I;
-    uint32_t Weight = getEdgeWeight(MBB, Succ);
-    uint32_t PrevSum = Sum;
-
-    Sum += Weight;
-    assert(Sum > PrevSum); (void) PrevSum;
-
+    uint32_t Weight = getEdgeWeight(MBB, I);
     if (Weight > MaxWeight) {
       MaxWeight = Weight;
-      MaxSucc = Succ;
+      MaxSucc = *I;
     }
   }
 
-  if (BranchProbability(MaxWeight, Sum) >= BranchProbability(4, 5))
+  if (getEdgeProbability(MBB, MaxSucc) >= BranchProbability(4, 5))
     return MaxSucc;
 
   return 0;