[llvm] r282511 - [SCEV] Make PendingLoopPredicates more frugal; NFCI

[Sanjoy Das via llvm-commits]

Author: sanjoy
Date: Tue Sep 27 13:01:38 2016
New Revision: 282511

URL: http://llvm.org/viewvc/llvm-project?rev=282511&view=rev
Log:
[SCEV] Make PendingLoopPredicates more frugal; NFCI

I don't expect `PendingLoopPredicates` to have very many
elements (e.g. when -O3'ing the sqlite3 amalgamation,
`PendingLoopPredicates` has at most 3 elements).  So now we use a
`SmallPtrSet` for it instead of the more heavyweight `DenseSet`.

Modified:
    llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp

Modified: llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ScalarEvolution.h?rev=282511&r1=282510&r2=282511&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ScalarEvolution.h (original)
+++ llvm/trunk/include/llvm/Analysis/ScalarEvolution.h Tue Sep 27 13:01:38 2016
@@ -533,7 +533,7 @@ private:
   ValueExprMapType ValueExprMap;
 
   /// Mark predicate values currently being processed by isImpliedCond.
-  DenseSet<Value *> PendingLoopPredicates;
+  SmallPtrSet<Value *, 6> PendingLoopPredicates;
 
   /// Set to true by isLoopBackedgeGuardedByCond when we're walking the set of
   /// conditions dominating the backedge of a loop.

Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=282511&r1=282510&r2=282511&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Tue Sep 27 13:01:38 2016
@@ -8064,11 +8064,11 @@ namespace {
 /// currently evaluating isImpliedCond.
 struct MarkPendingLoopPredicate {
   Value *Cond;
-  DenseSet<Value*> &LoopPreds;
+  SmallPtrSetImpl<Value *> &LoopPreds;
   bool Pending;
 
-  MarkPendingLoopPredicate(Value *C, DenseSet<Value*> &LP)
-    : Cond(C), LoopPreds(LP) {
+  MarkPendingLoopPredicate(Value *C, SmallPtrSetImpl<Value *> &LP)
+      : Cond(C), LoopPreds(LP) {
     Pending = !LoopPreds.insert(Cond).second;
   }
   ~MarkPendingLoopPredicate() {
@@ -9577,6 +9577,7 @@ ScalarEvolution::ScalarEvolution(ScalarE
     : F(Arg.F), HasGuards(Arg.HasGuards), TLI(Arg.TLI), AC(Arg.AC), DT(Arg.DT),
       LI(Arg.LI), CouldNotCompute(std::move(Arg.CouldNotCompute)),
       ValueExprMap(std::move(Arg.ValueExprMap)),
+      PendingLoopPredicates(std::move(Arg.PendingLoopPredicates)),
       WalkingBEDominatingConds(false), ProvingSplitPredicate(false),
       BackedgeTakenCounts(std::move(Arg.BackedgeTakenCounts)),
       PredicatedBackedgeTakenCounts(