[llvm-commits] [llvm] r136428 - /llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp

[Jakub Staszak]

Author: kuba
Date: Thu Jul 28 18:42:08 2011
New Revision: 136428

URL: http://llvm.org/viewvc/llvm-project?rev=136428&view=rev
Log:
Change LBH_TAKEN_WEIGHT to 124 (from 128). Right now, sum of
LBH_TAKEN_WEIGHT + LBH_NONTAKEN_WEIGHT = 128 which in _most_ cases reduce
number of rounding errors.


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=136428&r1=136427&r2=136428&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp Thu Jul 28 18:42:08 2011
@@ -52,7 +52,7 @@
   //          V
   //         BB1<-+
   //          |   |
-  //          |   | (Weight = 128)
+  //          |   | (Weight = 124)
   //          V   |
   //         BB2--+
   //          |
@@ -60,10 +60,10 @@
   //          V
   //         BB3
   //
-  // Probability of the edge BB2->BB1 = 128 / (128 + 4) = 0.9696..
-  // Probability of the edge BB2->BB3 = 4 / (128 + 4) = 0.0303..
+  // Probability of the edge BB2->BB1 = 124 / (124 + 4) = 0.96875
+  // Probability of the edge BB2->BB3 = 4 / (124 + 4) = 0.03125
 
-  static const uint32_t LBH_TAKEN_WEIGHT = 128;
+  static const uint32_t LBH_TAKEN_WEIGHT = 124;
   static const uint32_t LBH_NONTAKEN_WEIGHT = 4;
 
   // Standard weight value. Used when none of the heuristics set weight for