vendor/llvm/llvm-trunk-r290819

1 files changed, 91 insertions, 85 deletions

diff --git a/include/llvm/Analysis/ScalarEvolutionExpander.h b/include/llvm/Analysis/ScalarEvolutionExpander.h
index 1acf952ab70c..517592a3d049 100644
--- a/include/llvm/Analysis/ScalarEvolutionExpander.h
+++ b/include/llvm/Analysis/ScalarEvolutionExpander.h
@@ -14,12 +14,14 @@
 #ifndef LLVM_ANALYSIS_SCALAREVOLUTIONEXPANDER_H
 #define LLVM_ANALYSIS_SCALAREVOLUTIONEXPANDER_H
 
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/Analysis/ScalarEvolutionExpressions.h"
 #include "llvm/Analysis/ScalarEvolutionNormalization.h"
 #include "llvm/Analysis/TargetFolder.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/ValueHandle.h"
-#include <set>
 
 namespace llvm {
   class TargetTransformInfo;
@@ -28,8 +30,8 @@ namespace llvm {
   /// all materialized values are safe to speculate.
   bool isSafeToExpand(const SCEV *S, ScalarEvolution &SE);
 
-  /// This class uses information about analyze scalars to
-  /// rewrite expressions in canonical form.
+  /// This class uses information about analyze scalars to rewrite expressions
+  /// in canonical form.
   ///
   /// Clients should create an instance of this class when rewriting is needed,
   /// and destroy it when finished to allow the release of the associated
@@ -42,42 +44,41 @@ namespace llvm {
     const char* IVName;
 
     // InsertedExpressions caches Values for reuse, so must track RAUW.
-    std::map<std::pair<const SCEV *, Instruction *>, TrackingVH<Value> >
-      InsertedExpressions;
+    DenseMap<std::pair<const SCEV *, Instruction *>, TrackingVH<Value>>
+        InsertedExpressions;
+
     // InsertedValues only flags inserted instructions so needs no RAUW.
-    std::set<AssertingVH<Value> > InsertedValues;
-    std::set<AssertingVH<Value> > InsertedPostIncValues;
+    DenseSet<AssertingVH<Value>> InsertedValues;
+    DenseSet<AssertingVH<Value>> InsertedPostIncValues;
 
     /// A memoization of the "relevant" loop for a given SCEV.
     DenseMap<const SCEV *, const Loop *> RelevantLoops;
 
-    /// \brief Addrecs referring to any of the given loops are expanded
-    /// in post-inc mode. For example, expanding {1,+,1}<L> in post-inc mode
-    /// returns the add instruction that adds one to the phi for {0,+,1}<L>,
-    /// as opposed to a new phi starting at 1. This is only supported in
-    /// non-canonical mode.
+    /// Addrecs referring to any of the given loops are expanded in post-inc
+    /// mode. For example, expanding {1,+,1}<L> in post-inc mode returns the add
+    /// instruction that adds one to the phi for {0,+,1}<L>, as opposed to a new
+    /// phi starting at 1. This is only supported in non-canonical mode.
     PostIncLoopSet PostIncLoops;
 
-    /// \brief When this is non-null, addrecs expanded in the loop it indicates
-    /// should be inserted with increments at IVIncInsertPos.
+    /// When this is non-null, addrecs expanded in the loop it indicates should
+    /// be inserted with increments at IVIncInsertPos.
     const Loop *IVIncInsertLoop;
 
-    /// \brief When expanding addrecs in the IVIncInsertLoop loop, insert the IV
+    /// When expanding addrecs in the IVIncInsertLoop loop, insert the IV
     /// increment at this position.
     Instruction *IVIncInsertPos;
 
-    /// \brief Phis that complete an IV chain. Reuse
-    std::set<AssertingVH<PHINode> > ChainedPhis;
+    /// Phis that complete an IV chain. Reuse
+    DenseSet<AssertingVH<PHINode>> ChainedPhis;
 
-    /// \brief When true, expressions are expanded in "canonical" form. In
-    /// particular, addrecs are expanded as arithmetic based on a canonical
-    /// induction variable. When false, expression are expanded in a more
-    /// literal form.
+    /// When true, expressions are expanded in "canonical" form. In particular,
+    /// addrecs are expanded as arithmetic based on a canonical induction
+    /// variable. When false, expression are expanded in a more literal form.
     bool CanonicalMode;
 
-    /// \brief When invoked from LSR, the expander is in "strength reduction"
-    /// mode. The only difference is that phi's are only reused if they are
-    /// already in "expanded" form.
+    /// When invoked from LSR, the expander is in "strength reduction" mode. The
+    /// only difference is that phi's are only reused if they are already in
+    /// "expanded" form.
     bool LSRMode;
 
     typedef IRBuilder<TargetFolder> BuilderType;
@@ -130,7 +131,7 @@ namespace llvm {
     friend struct SCEVVisitor<SCEVExpander, Value*>;
 
   public:
-    /// \brief Construct a SCEVExpander in "canonical" mode.
+    /// Construct a SCEVExpander in "canonical" mode.
     explicit SCEVExpander(ScalarEvolution &se, const DataLayout &DL,
                           const char *name)
         : SE(se), DL(DL), IVName(name), IVIncInsertLoop(nullptr),
@@ -150,9 +151,9 @@ namespace llvm {
     void setDebugType(const char* s) { DebugType = s; }
 #endif
 
-    /// \brief Erase the contents of the InsertedExpressions map so that users
-    /// trying to expand the same expression into multiple BasicBlocks or
-    /// different places within the same BasicBlock can do so.
+    /// Erase the contents of the InsertedExpressions map so that users trying
+    /// to expand the same expression into multiple BasicBlocks or different
+    /// places within the same BasicBlock can do so.
     void clear() {
       InsertedExpressions.clear();
       InsertedValues.clear();
@@ -160,8 +161,8 @@ namespace llvm {
       ChainedPhis.clear();
     }
 
-    /// \brief Return true for expressions that may incur non-trivial cost to
-    /// evaluate at runtime.
+    /// Return true for expressions that may incur non-trivial cost to evaluate
+    /// at runtime.
     ///
     /// At is an optional parameter which specifies point in code where user is
     /// going to expand this expression. Sometimes this knowledge can lead to a
@@ -172,63 +173,60 @@ namespace llvm {
       return isHighCostExpansionHelper(Expr, L, At, Processed);
     }
 
-    /// \brief This method returns the canonical induction variable of the
-    /// specified type for the specified loop (inserting one if there is none).
-    /// A canonical induction variable starts at zero and steps by one on each
+    /// This method returns the canonical induction variable of the specified
+    /// type for the specified loop (inserting one if there is none).  A
+    /// canonical induction variable starts at zero and steps by one on each
     /// iteration.
     PHINode *getOrInsertCanonicalInductionVariable(const Loop *L, Type *Ty);
 
-    /// \brief Return the induction variable increment's IV operand.
+    /// Return the induction variable increment's IV operand.
     Instruction *getIVIncOperand(Instruction *IncV, Instruction *InsertPos,
                                  bool allowScale);
 
-    /// \brief Utility for hoisting an IV increment.
+    /// Utility for hoisting an IV increment.
     bool hoistIVInc(Instruction *IncV, Instruction *InsertPos);
 
-    /// \brief replace congruent phis with their most canonical
-    /// representative. Return the number of phis eliminated.
+    /// replace congruent phis with their most canonical representative. Return
+    /// the number of phis eliminated.
     unsigned replaceCongruentIVs(Loop *L, const DominatorTree *DT,
                                  SmallVectorImpl<WeakVH> &DeadInsts,
                                  const TargetTransformInfo *TTI = nullptr);
 
-    /// \brief Insert code to directly compute the specified SCEV expression
-    /// into the program.  The inserted code is inserted into the specified
-    /// block.
+    /// Insert code to directly compute the specified SCEV expression into the
+    /// program.  The inserted code is inserted into the specified block.
     Value *expandCodeFor(const SCEV *SH, Type *Ty, Instruction *I);
 
-    /// \brief Insert code to directly compute the specified SCEV expression
-    /// into the program.  The inserted code is inserted into the SCEVExpander's
-    /// current insertion point. If a type is specified, the result will be
-    /// expanded to have that type, with a cast if necessary.
+    /// Insert code to directly compute the specified SCEV expression into the
+    /// program.  The inserted code is inserted into the SCEVExpander's current
+    /// insertion point. If a type is specified, the result will be expanded to
+    /// have that type, with a cast if necessary.
     Value *expandCodeFor(const SCEV *SH, Type *Ty = nullptr);
 
 
-    /// \brief Generates a code sequence that evaluates this predicate.
-    /// The inserted instructions will be at position \p Loc.
-    /// The result will be of type i1 and will have a value of 0 when the
-    /// predicate is false and 1 otherwise.
+    /// Generates a code sequence that evaluates this predicate.  The inserted
+    /// instructions will be at position \p Loc.  The result will be of type i1
+    /// and will have a value of 0 when the predicate is false and 1 otherwise.
     Value *expandCodeForPredicate(const SCEVPredicate *Pred, Instruction *Loc);
 
-    /// \brief A specialized variant of expandCodeForPredicate, handling the
-    /// case when we are expanding code for a SCEVEqualPredicate.
+    /// A specialized variant of expandCodeForPredicate, handling the case when
+    /// we are expanding code for a SCEVEqualPredicate.
     Value *expandEqualPredicate(const SCEVEqualPredicate *Pred,
                                 Instruction *Loc);
 
-    /// \brief Generates code that evaluates if the \p AR expression will
-    /// overflow.
+    /// Generates code that evaluates if the \p AR expression will overflow.
     Value *generateOverflowCheck(const SCEVAddRecExpr *AR, Instruction *Loc,
                                  bool Signed);
 
-    /// \brief A specialized variant of expandCodeForPredicate, handling the
-    /// case when we are expanding code for a SCEVWrapPredicate.
+    /// A specialized variant of expandCodeForPredicate, handling the case when
+    /// we are expanding code for a SCEVWrapPredicate.
     Value *expandWrapPredicate(const SCEVWrapPredicate *P, Instruction *Loc);
 
-    /// \brief A specialized variant of expandCodeForPredicate, handling the
-    /// case when we are expanding code for a SCEVUnionPredicate.
+    /// A specialized variant of expandCodeForPredicate, handling the case when
+    /// we are expanding code for a SCEVUnionPredicate.
     Value *expandUnionPredicate(const SCEVUnionPredicate *Pred,
                                 Instruction *Loc);
 
-    /// \brief Set the current IV increment loop and position.
+    /// Set the current IV increment loop and position.
     void setIVIncInsertPos(const Loop *L, Instruction *Pos) {
       assert(!CanonicalMode &&
              "IV increment positions are not supported in CanonicalMode");
@@ -236,7 +234,7 @@ namespace llvm {
       IVIncInsertPos = Pos;
     }
 
-    /// \brief Enable post-inc expansion for addrecs referring to the given
+    /// Enable post-inc expansion for addrecs referring to the given
     /// loops. Post-inc expansion is only supported in non-canonical mode.
     void setPostInc(const PostIncLoopSet &L) {
       assert(!CanonicalMode &&
@@ -244,7 +242,7 @@ namespace llvm {
       PostIncLoops = L;
     }
 
-    /// \brief Disable all post-inc expansion.
+    /// Disable all post-inc expansion.
     void clearPostInc() {
       PostIncLoops.clear();
 
@@ -253,30 +251,29 @@ namespace llvm {
       InsertedPostIncValues.clear();
     }
 
-    /// \brief Disable the behavior of expanding expressions in canonical form
-    /// rather than in a more literal form. Non-canonical mode is useful for
-    /// late optimization passes.
+    /// Disable the behavior of expanding expressions in canonical form rather
+    /// than in a more literal form. Non-canonical mode is useful for late
+    /// optimization passes.
     void disableCanonicalMode() { CanonicalMode = false; }
 
     void enableLSRMode() { LSRMode = true; }
 
-    /// \brief Set the current insertion point. This is useful if multiple calls
-    /// to expandCodeFor() are going to be made with the same insert point and
-    /// the insert point may be moved during one of the expansions (e.g. if the
+    /// Set the current insertion point. This is useful if multiple calls to
+    /// expandCodeFor() are going to be made with the same insert point and the
+    /// insert point may be moved during one of the expansions (e.g. if the
     /// insert point is not a block terminator).
     void setInsertPoint(Instruction *IP) {
       assert(IP);
       Builder.SetInsertPoint(IP);
     }
 
-    /// \brief Clear the current insertion point. This is useful if the
-    /// instruction that had been serving as the insertion point may have been
-    /// deleted.
+    /// Clear the current insertion point. This is useful if the instruction
+    /// that had been serving as the insertion point may have been deleted.
     void clearInsertPoint() {
       Builder.ClearInsertionPoint();
     }
 
-    /// \brief Return true if the specified instruction was inserted by the code
+    /// Return true if the specified instruction was inserted by the code
     /// rewriter.  If so, the client should not modify the instruction.
     bool isInsertedInstruction(Instruction *I) const {
       return InsertedValues.count(I) || InsertedPostIncValues.count(I);
@@ -284,7 +281,14 @@ namespace llvm {
 
     void setChainedPhi(PHINode *PN) { ChainedPhis.insert(PN); }
 
-    /// \brief Try to find LLVM IR value for S available at the point At.
+    /// Try to find existing LLVM IR value for S available at the point At.
+    Value *getExactExistingExpansion(const SCEV *S, const Instruction *At,
+                                     Loop *L);
+
+    /// Try to find the ValueOffsetPair for S. The function is mainly used to
+    /// check whether S can be expanded cheaply.  If this returns a non-None
+    /// value, we know we can codegen the `ValueOffsetPair` into a suitable
+    /// expansion identical with S so that S can be expanded cheaply.
     ///
     /// L is a hint which tells in which loop to look for the suitable value.
     /// On success return value which is equivalent to the expanded S at point
@@ -292,44 +296,46 @@ namespace llvm {
     ///
     /// Note that this function does not perform an exhaustive search. I.e if it
     /// didn't find any value it does not mean that there is no such value.
-    Value *findExistingExpansion(const SCEV *S, const Instruction *At, Loop *L);
+    ///
+    Optional<ScalarEvolution::ValueOffsetPair>
+    getRelatedExistingExpansion(const SCEV *S, const Instruction *At, Loop *L);
 
   private:
     LLVMContext &getContext() const { return SE.getContext(); }
 
-    /// \brief Recursive helper function for isHighCostExpansion.
+    /// Recursive helper function for isHighCostExpansion.
     bool isHighCostExpansionHelper(const SCEV *S, Loop *L,
                                    const Instruction *At,
                                    SmallPtrSetImpl<const SCEV *> &Processed);
 
-    /// \brief Insert the specified binary operator, doing a small amount
-    /// of work to avoid inserting an obviously redundant operation.
+    /// Insert the specified binary operator, doing a small amount of work to
+    /// avoid inserting an obviously redundant operation.
     Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS, Value *RHS);
 
-    /// \brief Arrange for there to be a cast of V to Ty at IP, reusing an
-    /// existing cast if a suitable one exists, moving an existing cast if a
-    /// suitable one exists but isn't in the right place, or or creating a new
-    /// one.
+    /// Arrange for there to be a cast of V to Ty at IP, reusing an existing
+    /// cast if a suitable one exists, moving an existing cast if a suitable one
+    /// exists but isn't in the right place, or or creating a new one.
     Value *ReuseOrCreateCast(Value *V, Type *Ty,
                              Instruction::CastOps Op,
                              BasicBlock::iterator IP);
 
-    /// \brief Insert a cast of V to the specified type, which must be possible
-    /// with a noop cast, doing what we can to share the casts.
+    /// Insert a cast of V to the specified type, which must be possible with a
+    /// noop cast, doing what we can to share the casts.
     Value *InsertNoopCastOfTo(Value *V, Type *Ty);
 
-    /// \brief Expand a SCEVAddExpr with a pointer type into a GEP
-    /// instead of using ptrtoint+arithmetic+inttoptr.
+    /// Expand a SCEVAddExpr with a pointer type into a GEP instead of using
+    /// ptrtoint+arithmetic+inttoptr.
     Value *expandAddToGEP(const SCEV *const *op_begin,
                           const SCEV *const *op_end,
                           PointerType *PTy, Type *Ty, Value *V);
 
-    /// \brief Find a previous Value in ExprValueMap for expand.
-    Value *FindValueInExprValueMap(const SCEV *S, const Instruction *InsertPt);
+    /// Find a previous Value in ExprValueMap for expand.
+    ScalarEvolution::ValueOffsetPair
+    FindValueInExprValueMap(const SCEV *S, const Instruction *InsertPt);
 
     Value *expand(const SCEV *S);
 
-    /// \brief Determine the most "relevant" loop for the given SCEV.
+    /// Determine the most "relevant" loop for the given SCEV.
     const Loop *getRelevantLoop(const SCEV *);
 
     Value *visitConstant(const SCEVConstant *S) {