[PATCH] D32124: [BPI] Ignore tail while distributing the remaining probability from unreachanble

[Serguei Katkov via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL302883: [BPI] Ignore remainder while distributing the remaining probability from… (authored by skatkov).

Changed prior to commit:
  https://reviews.llvm.org/D32124?vs=97406&id=98733#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D32124

Files:
  llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
  llvm/trunk/test/Analysis/BranchProbabilityInfo/basic.ll


Index: llvm/trunk/test/Analysis/BranchProbabilityInfo/basic.ll
===================================================================
--- llvm/trunk/test/Analysis/BranchProbabilityInfo/basic.ll
+++ llvm/trunk/test/Analysis/BranchProbabilityInfo/basic.ll
@@ -452,7 +452,7 @@
                                  i32 3, label %case_d
                                  i32 4, label %case_e ], !prof !8
 ; CHECK: edge entry -> case_a probability is 0x00000800 / 0x80000000 = 0.00%
-; CHECK: edge entry -> case_b probability is 0x07fffe01 / 0x80000000 = 6.25%
+; CHECK: edge entry -> case_b probability is 0x07fffdff / 0x80000000 = 6.25%
 ; CHECK: edge entry -> case_c probability is 0x67fffdff / 0x80000000 = 81.25% [HOT edge]
 ; CHECK: edge entry -> case_d probability is 0x07fffdff / 0x80000000 = 6.25%
 ; CHECK: edge entry -> case_e probability is 0x07fffdff / 0x80000000 = 6.25%
@@ -495,7 +495,7 @@
                                  i32 4, label %case_e ], !prof !9
 ; CHECK: edge entry -> case_a probability is 0x00000400 / 0x80000000 = 0.00%
 ; CHECK: edge entry -> case_b probability is 0x00000400 / 0x80000000 = 0.00%
-; CHECK: edge entry -> case_c probability is 0x6aaaa800 / 0x80000000 = 83.33% [HOT edge]
+; CHECK: edge entry -> case_c probability is 0x6aaaa7ff / 0x80000000 = 83.33% [HOT edge]
 ; CHECK: edge entry -> case_d probability is 0x0aaaa7ff / 0x80000000 = 8.33%
 ; CHECK: edge entry -> case_e probability is 0x0aaaa7ff / 0x80000000 = 8.33%
 
@@ -535,7 +535,7 @@
                                  i32 4, label %case_e ], !prof !10
 ; CHECK: edge entry -> case_a probability is 0x00000000 / 0x80000000 = 0.00%
 ; CHECK: edge entry -> case_b probability is 0x00000400 / 0x80000000 = 0.00%
-; CHECK: edge entry -> case_c probability is 0x6e08fa2e / 0x80000000 = 85.96% [HOT edge]
+; CHECK: edge entry -> case_c probability is 0x6e08fa2d / 0x80000000 = 85.96% [HOT edge]
 ; CHECK: edge entry -> case_d probability is 0x08fb80e9 / 0x80000000 = 7.02%
 ; CHECK: edge entry -> case_e probability is 0x08fb80e9 / 0x80000000 = 7.02%
 
Index: llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
===================================================================
--- llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
+++ llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
@@ -301,6 +301,8 @@
       WeightSum += Weights[i];
     }
   }
+  assert(WeightSum <= UINT32_MAX &&
+         "Expected weights to scale down to 32 bits");
 
   if (WeightSum == 0 || ReachableIdxs.size() == 0) {
     for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
@@ -328,21 +330,14 @@
     // the difference between reachable blocks.
     if (ToDistribute > BranchProbability::getZero()) {
       BranchProbability PerEdge = ToDistribute / ReachableIdxs.size();
-      for (auto i : ReachableIdxs) {
+      for (auto i : ReachableIdxs)
         BP[i] += PerEdge;
-        ToDistribute -= PerEdge;
-      }
-      // Tail goes to the first reachable edge.
-      BP[ReachableIdxs[0]] += ToDistribute;
     }
   }
 
   for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
     setEdgeProbability(BB, i, BP[i]);
 
-  assert(WeightSum <= UINT32_MAX &&
-         "Expected weights to scale down to 32 bits");
-
   return true;
 }
 


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