[PATCH] D33301: [Statistics] Add a method to atomically update a statistic that contains a maximum

[Phabricator via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL303318: [Statistics] Add a method to atomically update a statistic that contains a… (authored by ctopper).

Changed prior to commit:
  https://reviews.llvm.org/D33301?vs=99357&id=99381#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D33301

Files:
  llvm/trunk/include/llvm/ADT/Statistic.h
  llvm/trunk/lib/Analysis/CallGraphSCCPass.cpp
  llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
  llvm/trunk/lib/Transforms/Scalar/SROA.cpp


Index: llvm/trunk/lib/Transforms/Scalar/SROA.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Scalar/SROA.cpp
+++ llvm/trunk/lib/Transforms/Scalar/SROA.cpp
@@ -3898,8 +3898,7 @@
   }
 
   NumAllocaPartitionUses += NumUses;
-  MaxUsesPerAllocaPartition =
-      std::max<unsigned>(NumUses, MaxUsesPerAllocaPartition);
+  MaxUsesPerAllocaPartition.updateMax(NumUses);
 
   // Now that we've processed all the slices in the new partition, check if any
   // PHIs or Selects would block promotion.
@@ -4016,8 +4015,7 @@
   }
 
   NumAllocaPartitions += NumPartitions;
-  MaxPartitionsPerAlloca =
-      std::max<unsigned>(NumPartitions, MaxPartitionsPerAlloca);
+  MaxPartitionsPerAlloca.updateMax(NumPartitions);
 
   // Migrate debug information from the old alloca to the new alloca(s)
   // and the individual partitions.
Index: llvm/trunk/lib/Analysis/CallGraphSCCPass.cpp
===================================================================
--- llvm/trunk/lib/Analysis/CallGraphSCCPass.cpp
+++ llvm/trunk/lib/Analysis/CallGraphSCCPass.cpp
@@ -477,10 +477,8 @@
     if (DevirtualizedCall)
       DEBUG(dbgs() << "  CGSCCPASSMGR: Stopped iteration after " << Iteration
                    << " times, due to -max-cg-scc-iterations\n");
-    
-    if (Iteration > MaxSCCIterations)
-      MaxSCCIterations = Iteration;
-    
+
+    MaxSCCIterations.updateMax(Iteration);
   }
   Changed |= doFinalization(CG);
   return Changed;
Index: llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
+++ llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
@@ -110,8 +110,8 @@
          Builder.FuncInfo.StatepointStackSlots.size() &&
          "Broken invariant");
 
-  StatepointMaxSlotsRequired = std::max<unsigned long>(
-      StatepointMaxSlotsRequired, Builder.FuncInfo.StatepointStackSlots.size());
+  StatepointMaxSlotsRequired.updateMax(
+      Builder.FuncInfo.StatepointStackSlots.size());
 
   return SpillSlot;
 }
Index: llvm/trunk/include/llvm/ADT/Statistic.h
===================================================================
--- llvm/trunk/include/llvm/ADT/Statistic.h
+++ llvm/trunk/include/llvm/ADT/Statistic.h
@@ -101,6 +101,16 @@
     return init();
   }
 
+  void updateMax(unsigned V) {
+    unsigned PrevMax = Value.load(std::memory_order_relaxed);
+    // Keep trying to update max until we succeed or another thread produces
+    // a bigger max than us.
+    while (V > PrevMax && !Value.compare_exchange_weak(
+                              PrevMax, V, std::memory_order_relaxed)) {
+    }
+    init();
+  }
+
 #else  // Statistics are disabled in release builds.
 
   const Statistic &operator=(unsigned Val) {
@@ -131,6 +141,8 @@
     return *this;
   }
 
+  void updateMax(unsigned V) {}
+
 #endif  // !defined(NDEBUG) || defined(LLVM_ENABLE_STATS)
 
 protected:


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D33301.99381.patch
Type: text/x-patch
Size: 2978 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20170518/de17d55e/attachment.bin>