//
//===----------------------------------------------------------------------===//
-#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H
-#define LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H
+#ifndef LLVM_ANALYSIS_SCALAREVOLUTIONEXPANDER_H
+#define LLVM_ANALYSIS_SCALAREVOLUTIONEXPANDER_H
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/ScalarEvolutionNormalization.h"
-#include "llvm/Support/IRBuilder.h"
-#include "llvm/Support/TargetFolder.h"
-#include "llvm/Support/ValueHandle.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,
/// memory.
class SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
ScalarEvolution &SE;
- std::map<std::pair<const SCEV *, Instruction *>, AssertingVH<Value> >
+ 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;
- /// PostIncLoops - Addrecs referring to any of the given loops are expanded
+ /// 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;
- /// IVIncInsertPos - When this is non-null, addrecs expanded in the
- /// loop it indicates should be inserted with increments at
- /// IVIncInsertPos.
+ /// \brief When this is non-null, addrecs expanded in the loop it indicates
+ /// should be inserted with increments at IVIncInsertPos.
const Loop *IVIncInsertLoop;
- /// IVIncInsertPos - When expanding addrecs in the IVIncInsertLoop loop,
- /// insert the IV increment at this position.
+ /// \brief When expanding addrecs in the IVIncInsertLoop loop, insert the IV
+ /// increment at this position.
Instruction *IVIncInsertPos;
- /// CanonicalMode - 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.
+ /// \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:
- /// SCEVExpander - Construct a SCEVExpander in "canonical" mode.
- explicit SCEVExpander(ScalarEvolution &se)
- : SE(se), IVIncInsertLoop(0), CanonicalMode(true),
- Builder(se.getContext(), TargetFolder(se.TD)) {}
+ /// \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();
InsertedValues.clear();
InsertedPostIncValues.clear();
+ ChainedPhis.clear();
}
- /// 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.
- PHINode *getOrInsertCanonicalInductionVariable(const Loop *L,
- const Type *Ty);
-
- /// expandCodeFor - 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, const Type *Ty, Instruction *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);
+ }
- /// setIVIncInsertPos - Set the current IV increment loop and position.
+ /// \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 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.
+ Value *expandEqualPredicate(const SCEVEqualPredicate *Pred,
+ Instruction *Loc);
+
+ /// \brief 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.
void setIVIncInsertPos(const Loop *L, Instruction *Pos) {
assert(!CanonicalMode &&
"IV increment positions are not supported in CanonicalMode");
IVIncInsertPos = Pos;
}
- /// setPostInc - Enable post-inc expansion for addrecs referring to the
- /// given loops. Post-inc expansion is only supported in non-canonical
- /// mode.
+ /// \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;
}
- /// clearPostInc - Disable all post-inc expansion.
+ /// \brief Disable all post-inc expansion.
void clearPostInc() {
PostIncLoops.clear();
InsertedPostIncValues.clear();
}
- /// disableCanonicalMode - 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.
+ /// \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; }
- /// clearInsertPoint - Clear the current insertion point. This is useful
- /// if the instruction that had been serving as the insertion point may
- /// have been deleted.
+ 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();
}
+ /// \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);
+ }
+
+ void setChainedPhi(PHINode *PN) { ChainedPhis.insert(PN); }
+
+ /// \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 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);
+
private:
LLVMContext &getContext() const { return SE.getContext(); }
- /// InsertBinop - Insert the specified binary operator, doing a small amount
+ /// \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);
- /// ReuseOrCreateCast - Arange 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, const Type *Ty,
+ /// \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);
- /// InsertNoopCastOfTo - 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, const Type *Ty);
+ /// \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);
- /// expandAddToGEP - Expand a SCEVAddExpr with a pointer type into a GEP
+ /// \brief 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,
- const PointerType *PTy, const Type *Ty, Value *V);
+ PointerType *PTy, Type *Ty, Value *V);
Value *expand(const SCEV *S);
- /// 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(const SCEV *SH, const Type *Ty = 0);
+ /// \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);
- /// 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) || InsertedPostIncValues.count(I);
- }
+ /// \brief Determine the most "relevant" loop for the given SCEV.
+ const Loop *getRelevantLoop(const SCEV *);
Value *visitConstant(const SCEVConstant *S) {
return S->getValue();
void rememberInstruction(Value *I);
- void restoreInsertPoint(BasicBlock *BB, BasicBlock::iterator 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,
- const Type *ExpandTy,
- const Type *IntTy);
+ Type *ExpandTy,
+ Type *IntTy,
+ Type *&TruncTy,
+ bool &InvertStep);
+ Value *expandIVInc(PHINode *PN, Value *StepV, const Loop *L,
+ Type *ExpandTy, Type *IntTy, bool useSubtract);
};
}