[llvm] r318353 - [CodeGen] Fix the branch probability assertion in r318202

[Rong Xu via llvm-commits]

Author: xur
Date: Wed Nov 15 16:14:05 2017
New Revision: 318353

URL: http://llvm.org/viewvc/llvm-project?rev=318353&view=rev
Log:
[CodeGen] Fix the branch probability assertion in r318202

Due to integer precision, we might have numerator greater than denominator in
the branch probability scaling. Add a check to prevent this from happening.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=318353&r1=318352&r2=318353&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Wed Nov 15 16:14:05 2017
@@ -9847,8 +9847,10 @@ static BranchProbability scaleCaseProbal
   if (PeeledCaseProb == BranchProbability::getOne())
     return BranchProbability::getZero();
   BranchProbability SwitchProb = PeeledCaseProb.getCompl();
-  return BranchProbability(CaseProb.getNumerator(),
-                           SwitchProb.scale(CaseProb.getDenominator()));
+
+  uint32_t Numerator = CaseProb.getNumerator();
+  uint32_t Denominator = SwitchProb.scale(CaseProb.getDenominator());
+  return BranchProbability(Numerator, std::max(Numerator, Denominator));
 }
 
 // Try to peel the top probability case if it exceeds the threshold.