[IRCE] Don't use an allocator for range checks; NFC

The InductiveRangeCheck struct is only five words long; so passing these
around value is fine.  The allocator makes the code look more complex
than it is.

llvm-svn: 270309

1 files changed, 28 insertions, 37 deletions

diff --git a/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp b/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
index 984b4c4..5b4b6c1 100644
--- a/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
@@ -179,8 +179,6 @@ public:
     const SCEV *getEnd() const { return End; }
   };
 
-  typedef SpecificBumpPtrAllocator<InductiveRangeCheck> AllocatorTy;
-
   /// This is the value the condition of the branch needs to evaluate to for the
   /// branch to take the hot successor (see (1) above).
   bool getPassingDirection() { return true; }
@@ -191,16 +189,13 @@ public:
   Optional<Range> computeSafeIterationSpace(ScalarEvolution &SE,
                                             const SCEVAddRecExpr *IndVar) const;
 
-  /// Create an inductive range check out of BI if possible, else return
-  /// nullptr.
-  static InductiveRangeCheck *create(AllocatorTy &Alloc, BranchInst *BI,
-                                     Loop *L, ScalarEvolution &SE,
-                                     BranchProbabilityInfo &BPI);
+  /// Create an inductive range check out of BI if possible, else return None.
+  static Optional<InductiveRangeCheck> create(BranchInst *BI, Loop *L,
+                                              ScalarEvolution &SE,
+                                              BranchProbabilityInfo &BPI);
 };
 
 class InductiveRangeCheckElimination : public LoopPass {
-  InductiveRangeCheck::AllocatorTy Allocator;
-
 public:
   static char ID;
   InductiveRangeCheckElimination() : LoopPass(ID) {
@@ -376,19 +371,17 @@ InductiveRangeCheck::parseRangeCheck(Loop *L, ScalarEvolution &SE,
   return InductiveRangeCheck::RANGE_CHECK_UNKNOWN;
 }
 
-
-InductiveRangeCheck *
-InductiveRangeCheck::create(InductiveRangeCheck::AllocatorTy &A, BranchInst *BI,
-                            Loop *L, ScalarEvolution &SE,
+Optional<InductiveRangeCheck>
+InductiveRangeCheck::create(BranchInst *BI, Loop *L, ScalarEvolution &SE,
                             BranchProbabilityInfo &BPI) {
 
   if (BI->isUnconditional() || BI->getParent() == L->getLoopLatch())
-    return nullptr;
+    return None;
 
   BranchProbability LikelyTaken(15, 16);
 
   if (BPI.getEdgeProbability(BI->getParent(), (unsigned) 0) < LikelyTaken)
-    return nullptr;
+    return None;
 
   Value *Length = nullptr;
   const SCEV *IndexSCEV = nullptr;
@@ -397,7 +390,7 @@ InductiveRangeCheck::create(InductiveRangeCheck::AllocatorTy &A, BranchInst *BI,
                                                      IndexSCEV, Length);
 
   if (RCKind == InductiveRangeCheck::RANGE_CHECK_UNKNOWN)
-    return nullptr;
+    return None;
 
   assert(IndexSCEV && "contract with SplitRangeCheckCondition!");
   assert((!(RCKind & InductiveRangeCheck::RANGE_CHECK_UPPER) || Length) &&
@@ -408,14 +401,14 @@ InductiveRangeCheck::create(InductiveRangeCheck::AllocatorTy &A, BranchInst *BI,
       IndexAddRec && (IndexAddRec->getLoop() == L) && IndexAddRec->isAffine();
 
   if (!IsAffineIndex)
-    return nullptr;
-
-  InductiveRangeCheck *IRC = new (A.Allocate()) InductiveRangeCheck;
-  IRC->Length = Length;
-  IRC->Offset = IndexAddRec->getStart();
-  IRC->Scale = IndexAddRec->getStepRecurrence(SE);
-  IRC->Branch = BI;
-  IRC->Kind = RCKind;
+    return None;
+
+  InductiveRangeCheck IRC;
+  IRC.Length = Length;
+  IRC.Offset = IndexAddRec->getStart();
+  IRC.Scale = IndexAddRec->getStepRecurrence(SE);
+  IRC.Branch = BI;
+  IRC.Kind = RCKind;
   return IRC;
 }
 
@@ -1396,17 +1389,15 @@ bool InductiveRangeCheckElimination::runOnLoop(Loop *L, LPPassManager &LPM) {
   }
 
   LLVMContext &Context = Preheader->getContext();
-  InductiveRangeCheck::AllocatorTy IRCAlloc;
-  SmallVector<InductiveRangeCheck *, 16> RangeChecks;
+  SmallVector<InductiveRangeCheck, 16> RangeChecks;
   ScalarEvolution &SE = getAnalysis<ScalarEvolutionWrapperPass>().getSE();
   BranchProbabilityInfo &BPI =
       getAnalysis<BranchProbabilityInfoWrapperPass>().getBPI();
 
   for (auto BBI : L->getBlocks())
     if (BranchInst *TBI = dyn_cast<BranchInst>(BBI->getTerminator()))
-      if (InductiveRangeCheck *IRC =
-          InductiveRangeCheck::create(IRCAlloc, TBI, L, SE, BPI))
-        RangeChecks.push_back(IRC);
+      if (auto MaybeIRC = InductiveRangeCheck::create(TBI, L, SE, BPI))
+        RangeChecks.push_back(*MaybeIRC);
 
   if (RangeChecks.empty())
     return false;
@@ -1415,8 +1406,8 @@ bool InductiveRangeCheckElimination::runOnLoop(Loop *L, LPPassManager &LPM) {
     OS << "irce: looking at loop "; L->print(OS);
     OS << "irce: loop has " << RangeChecks.size()
        << " inductive range checks: \n";
-    for (InductiveRangeCheck *IRC : RangeChecks)
-      IRC->print(OS);
+    for (InductiveRangeCheck &IRC : RangeChecks)
+      IRC.print(OS);
   };
 
   DEBUG(PrintRecognizedRangeChecks(dbgs()));
@@ -1442,11 +1433,11 @@ bool InductiveRangeCheckElimination::runOnLoop(Loop *L, LPPassManager &LPM) {
   Optional<InductiveRangeCheck::Range> SafeIterRange;
   Instruction *ExprInsertPt = Preheader->getTerminator();
 
-  SmallVector<InductiveRangeCheck *, 4> RangeChecksToEliminate;
+  SmallVector<InductiveRangeCheck, 4> RangeChecksToEliminate;
 
   IRBuilder<> B(ExprInsertPt);
-  for (InductiveRangeCheck *IRC : RangeChecks) {
-    auto Result = IRC->computeSafeIterationSpace(SE, IndVar);
+  for (InductiveRangeCheck &IRC : RangeChecks) {
+    auto Result = IRC.computeSafeIterationSpace(SE, IndVar);
     if (Result.hasValue()) {
       auto MaybeSafeIterRange =
           IntersectRange(SE, SafeIterRange, Result.getValue());
@@ -1479,11 +1470,11 @@ bool InductiveRangeCheckElimination::runOnLoop(Loop *L, LPPassManager &LPM) {
 
     // Optimize away the now-redundant range checks.
 
-    for (InductiveRangeCheck *IRC : RangeChecksToEliminate) {
-      ConstantInt *FoldedRangeCheck = IRC->getPassingDirection()
+    for (InductiveRangeCheck &IRC : RangeChecksToEliminate) {
+      ConstantInt *FoldedRangeCheck = IRC.getPassingDirection()
                                           ? ConstantInt::getTrue(Context)
                                           : ConstantInt::getFalse(Context);
-      IRC->getBranch()->setCondition(FoldedRangeCheck);
+      IRC.getBranch()->setCondition(FoldedRangeCheck);
     }
   }