[llvm] r318686 - Revert "[SelectionDAG] Make sorting predicate stronger to remove non-deterministic ordering"

[Mandeep Singh Grang via llvm-commits]

Author: mgrang
Date: Mon Nov 20 11:17:11 2017
New Revision: 318686

URL: http://llvm.org/viewvc/llvm-project?rev=318686&view=rev
Log:
Revert "[SelectionDAG] Make sorting predicate stronger to remove non-deterministic ordering"

This broke the bots. Reverting this until I can fix the failures.

This reverts commit 5a3db2856d12a3c4b400f487d39f8f05989e79f0.

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=318686&r1=318685&r2=318686&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Mon Nov 20 11:17:11 2017
@@ -9350,12 +9350,10 @@ bool SelectionDAGBuilder::buildBitTests(
 
   BitTestInfo BTI;
   std::sort(CBV.begin(), CBV.end(), [](const CaseBits &a, const CaseBits &b) {
-    // Sort by probability first, number of bits second, bit mask third.
+    // Sort by probability first, number of bits second.
     if (a.ExtraProb != b.ExtraProb)
       return a.ExtraProb > b.ExtraProb;
-    if (a.Bits != b.Bits)
-      return a.Bits > b.Bits;
-    return a.Mask < b.Mask;
+    return a.Bits > b.Bits;
   });
 
   for (auto &CB : CBV) {
@@ -9544,13 +9542,10 @@ void SelectionDAGBuilder::lowerWorkItem(
   }
 
   if (TM.getOptLevel() != CodeGenOpt::None) {
-    // Here, we order cases by probability so the most likely case will be
-    // checked first. However, two clusters can have the same probability in
-    // which case their relative ordering is non-deterministic. So we use Low
-    // as a tie-breaker as clusters are guaranteed to never overlap.
+    // Order cases by probability so the most likely case will be checked first.
     std::sort(W.FirstCluster, W.LastCluster + 1,
               [](const CaseCluster &a, const CaseCluster &b) {
-      return a.Prob != b.Prob ? a.Prob > b.Prob : a.Low < b.Low;
+      return a.Prob > b.Prob;
     });
 
     // Rearrange the case blocks so that the last one falls through if possible