//
//===----------------------------------------------------------------------===//
-#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H
-#define LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H
+#ifndef LLVM_ANALYSIS_SCALAREVOLUTIONEXPANDER_H
+#define LLVM_ANALYSIS_SCALAREVOLUTIONEXPANDER_H
-#include "llvm/Instructions.h"
-#include "llvm/Type.h"
-#include "llvm/Analysis/ScalarEvolution.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 {
- /// SCEVExpander - This class uses information about analyze scalars to
+ class TargetTransformInfo;
+
+ /// Return true if the given expression is safe to expand in the sense that
+ /// 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.
///
/// Clients should create an instance of this class when rewriting is needed,
- /// and destroy it when finished to allow the release of the associated
+ /// and destroy it when finished to allow the release of the associated
/// memory.
- struct SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
+ class SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
ScalarEvolution &SE;
- std::map<SCEVHandle, AssertingVH<Value> > InsertedExpressions;
- std::set<Value*> InsertedValues;
-
- BasicBlock::iterator InsertPt;
+ const DataLayout &DL;
+
+ // New instructions receive a name to identifies them with the current pass.
+ const char* IVName;
+
+ // InsertedExpressions caches Values for reuse, so must track RAUW.
+ std::map<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;
+
+ /// 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.
+ PostIncLoopSet PostIncLoops;
+
+ /// \brief 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
+ /// increment at this position.
+ Instruction *IVIncInsertPos;
+
+ /// \brief Phis that complete an IV chain. Reuse
+ std::set<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.
+ 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.
+ bool LSRMode;
+
+ typedef IRBuilder<true, TargetFolder> BuilderType;
+ BuilderType Builder;
+
+#ifndef NDEBUG
+ const char *DebugType;
+#endif
friend struct SCEVVisitor<SCEVExpander, Value*>;
+
public:
- explicit SCEVExpander(ScalarEvolution &se)
- : SE(se) {}
+ /// \brief Construct a SCEVExpander in "canonical" mode.
+ explicit SCEVExpander(ScalarEvolution &se, const DataLayout &DL,
+ const char *name)
+ : SE(se), DL(DL), IVName(name), IVIncInsertLoop(nullptr),
+ IVIncInsertPos(nullptr), CanonicalMode(true), LSRMode(false),
+ Builder(se.getContext(), TargetFolder(DL)) {
+#ifndef NDEBUG
+ DebugType = "";
+#endif
+ }
- /// clear - Erase the contents of the InsertedExpressions map so that users
+#ifndef NDEBUG
+ 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.
- void clear() { InsertedExpressions.clear(); }
+ void clear() {
+ InsertedExpressions.clear();
+ InsertedValues.clear();
+ InsertedPostIncValues.clear();
+ ChainedPhis.clear();
+ }
- /// isInsertedInstruction - 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);
+ /// \brief 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 more accurate cost estimation.
+ bool isHighCostExpansion(const SCEV *Expr, Loop *L,
+ const Instruction *At = nullptr) {
+ SmallPtrSet<const SCEV *, 8> Processed;
+ return isHighCostExpansionHelper(Expr, L, At, Processed);
}
- /// isInsertedExpression - Return true if the the code rewriter has a
- /// Value* recorded for the given expression.
- bool isInsertedExpression(const SCEV *S) const {
- return InsertedExpressions.count(S);
+ /// \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
+ /// iteration.
+ PHINode *getOrInsertCanonicalInductionVariable(const Loop *L, Type *Ty);
+
+ /// \brief Return the induction variable increment's IV operand.
+ Instruction *getIVIncOperand(Instruction *IncV, Instruction *InsertPos,
+ bool allowScale);
+
+ /// \brief 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.
+ 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.
+ Value *expandCodeFor(const SCEV *SH, Type *Ty, Instruction *I);
+
+ /// \brief 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");
+ IVIncInsertLoop = L;
+ IVIncInsertPos = Pos;
}
- /// getOrInsertCanonicalInductionVariable - 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.
- Value *getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty);
-
- /// addInsertedValue - Remember the specified instruction as being the
- /// canonical form for the specified SCEV.
- void addInsertedValue(Value *V, const SCEV *S) {
- InsertedExpressions[S] = V;
- InsertedValues.insert(V);
+ /// \brief 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 &&
+ "Post-inc expansion is not supported in CanonicalMode");
+ PostIncLoops = L;
}
- void setInsertionPoint(BasicBlock::iterator NewIP) { InsertPt = NewIP; }
+ /// \brief Disable all post-inc expansion.
+ void clearPostInc() {
+ PostIncLoops.clear();
- BasicBlock::iterator getInsertionPoint() const { return InsertPt; }
+ // When we change the post-inc loop set, cached expansions may no
+ // longer be valid.
+ InsertedPostIncValues.clear();
+ }
- /// expandCodeFor - 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(SCEVHandle SH, const Type *Ty = 0);
+ /// \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.
+ void disableCanonicalMode() { CanonicalMode = false; }
- /// expandCodeFor - Insert code to directly compute the specified SCEV
- /// expression into the program. The inserted code is inserted into the
- /// specified block.
- Value *expandCodeFor(SCEVHandle SH, const Type *Ty,
- BasicBlock::iterator IP) {
- setInsertionPoint(IP);
- return expandCodeFor(SH, Ty);
+ void enableLSRMode() { LSRMode = true; }
+
+ /// \brief 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();
}
- /// InsertCastOfTo - Insert a cast of V to the specified type, doing what
- /// we can to share the casts.
- Value *InsertCastOfTo(Instruction::CastOps opcode, Value *V,
- const Type *Ty);
+ /// \brief 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);
+ }
- /// InsertNoopCastOfTo - Insert a cast of V to the specified type,
- /// which must be possible with a noop cast.
- Value *InsertNoopCastOfTo(Value *V, const Type *Ty);
+ void setChainedPhi(PHINode *PN) { ChainedPhis.insert(PN); }
- /// InsertBinop - 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, BasicBlock::iterator InsertPt);
+ /// \brief Try to find LLVM IR value for 'S' available at the point 'At'.
+ // '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
+ // 'At'. Return nullptr if value was not found.
+ // Note that this function does not perform 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);
private:
- /// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP
+ LLVMContext &getContext() const { return SE.getContext(); }
+
+ /// \brief 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.
+ 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.
+ 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.
+ Value *InsertNoopCastOfTo(Value *V, Type *Ty);
+
+ /// \brief Expand a SCEVAddExpr with a pointer type into a GEP
/// instead of using ptrtoint+arithmetic+inttoptr.
- Value *expandAddToGEP(const SCEVHandle *op_begin, const SCEVHandle *op_end,
- const PointerType *PTy, const Type *Ty, Value *V);
+ Value *expandAddToGEP(const SCEV *const *op_begin,
+ const SCEV *const *op_end,
+ PointerType *PTy, Type *Ty, Value *V);
Value *expand(const SCEV *S);
+ /// \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.
+ Value *expandCodeFor(const SCEV *SH, Type *Ty = nullptr);
+
+ /// \brief Determine the most "relevant" loop for the given SCEV.
+ const Loop *getRelevantLoop(const SCEV *);
+
Value *visitConstant(const SCEVConstant *S) {
return S->getValue();
}
Value *visitUnknown(const SCEVUnknown *S) {
return S->getValue();
}
+
+ void rememberInstruction(Value *I);
+
+ bool isNormalAddRecExprPHI(PHINode *PN, Instruction *IncV, const Loop *L);
+
+ bool isExpandedAddRecExprPHI(PHINode *PN, Instruction *IncV, const Loop *L);
+
+ Value *expandAddRecExprLiterally(const SCEVAddRecExpr *);
+ PHINode *getAddRecExprPHILiterally(const SCEVAddRecExpr *Normalized,
+ const Loop *L,
+ Type *ExpandTy,
+ Type *IntTy,
+ Type *&TruncTy,
+ bool &InvertStep);
+ Value *expandIVInc(PHINode *PN, Value *StepV, const Loop *L,
+ Type *ExpandTy, Type *IntTy, bool useSubtract);
};
}
#endif
-
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