[llvm-commits] [llvm] r136398 - /llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp

[Jakub Staszak]

Author: kuba
Date: Thu Jul 28 16:33:46 2011
New Revision: 136398

URL: http://llvm.org/viewvc/llvm-project?rev=136398&view=rev
Log:
Add InEdges (edges from header to the loop) in Loop Branch Heuristics, so
there is no frequency difference whether condition is in the header or in
the latch.

Modified:
    llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp

Modified: llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp?rev=136398&r1=136397&r2=136398&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp Thu Jul 28 16:33:46 2011
@@ -205,6 +205,9 @@
 
   SmallVector<BasicBlock *, 8> BackEdges;
   SmallVector<BasicBlock *, 8> ExitingEdges;
+  SmallVector<BasicBlock *, 8> InEdges; // Edges from header to the loop.
+
+  bool isHeader = BB == L->getHeader();
 
   for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I) {
     BasicBlock *Succ = *I;
@@ -213,6 +216,8 @@
       ExitingEdges.push_back(Succ);
     else if (Succ == L->getHeader())
       BackEdges.push_back(Succ);
+    else if (isHeader)
+      InEdges.push_back(Succ);
   }
 
   if (uint32_t numBackEdges = BackEdges.size()) {
@@ -227,6 +232,18 @@
     }
   }
 
+  if (uint32_t numInEdges = InEdges.size()) {
+    uint32_t inWeight = LBH_TAKEN_WEIGHT / numInEdges;
+    if (inWeight < NORMAL_WEIGHT)
+      inWeight = NORMAL_WEIGHT;
+
+    for (SmallVector<BasicBlock *, 8>::iterator EI = InEdges.begin(),
+         EE = InEdges.end(); EI != EE; ++EI) {
+      BasicBlock *Back = *EI;
+      BP->setEdgeWeight(BB, Back, inWeight);
+    }
+  }
+
   uint32_t numExitingEdges = ExitingEdges.size();
   if (uint32_t numNonExitingEdges = numSuccs - numExitingEdges) {
     uint32_t exitWeight = LBH_NONTAKEN_WEIGHT / numNonExitingEdges;