llvm-6502/include/llvm/Analysis/ScalarEvolutionExpander.h
Alexander Kornienko cd52a7a381 Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC)
Apparently, the style needs to be agreed upon first.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240390 91177308-0d34-0410-b5e6-96231b3b80d8
2015-06-23 09:49:53 +00:00

281 lines
11 KiB
C++

//===---- llvm/Analysis/ScalarEvolutionExpander.h - SCEV Exprs --*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the classes used to generate code from scalar expressions.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_SCALAREVOLUTIONEXPANDER_H
#define LLVM_ANALYSIS_SCALAREVOLUTIONEXPANDER_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;
/// 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
/// memory.
class SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
ScalarEvolution &SE;
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:
/// \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
}
#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();
}
/// \brief Return true for expressions that may incur non-trivial cost to
/// evaluate at runtime.
bool isHighCostExpansion(const SCEV *Expr, Loop *L) {
SmallPtrSet<const SCEV *, 8> Processed;
return isHighCostExpansionHelper(Expr, L, 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
/// 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;
}
/// \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;
}
/// \brief Disable all post-inc expansion.
void clearPostInc() {
PostIncLoops.clear();
// When we change the post-inc loop set, cached expansions may no
// longer be valid.
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.
void disableCanonicalMode() { CanonicalMode = false; }
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); }
private:
LLVMContext &getContext() const { return SE.getContext(); }
/// \brief Recursive helper function for isHighCostExpansion.
bool isHighCostExpansionHelper(const SCEV *S, Loop *L,
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 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 *visitTruncateExpr(const SCEVTruncateExpr *S);
Value *visitZeroExtendExpr(const SCEVZeroExtendExpr *S);
Value *visitSignExtendExpr(const SCEVSignExtendExpr *S);
Value *visitAddExpr(const SCEVAddExpr *S);
Value *visitMulExpr(const SCEVMulExpr *S);
Value *visitUDivExpr(const SCEVUDivExpr *S);
Value *visitAddRecExpr(const SCEVAddRecExpr *S);
Value *visitSMaxExpr(const SCEVSMaxExpr *S);
Value *visitUMaxExpr(const SCEVUMaxExpr *S);
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