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957 lines
41 KiB
C++
957 lines
41 KiB
C++
//===- llvm/Analysis/ScalarEvolution.h - Scalar Evolution -------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// The ScalarEvolution class is an LLVM pass which can be used to analyze and
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// categorize scalar expressions in loops. It specializes in recognizing
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// general induction variables, representing them with the abstract and opaque
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// SCEV class. Given this analysis, trip counts of loops and other important
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// properties can be obtained.
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//
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// This analysis is primarily useful for induction variable substitution and
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// strength reduction.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_H
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#define LLVM_ANALYSIS_SCALAREVOLUTION_H
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#include "llvm/ADT/DenseSet.h"
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#include "llvm/ADT/FoldingSet.h"
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#include "llvm/IR/ConstantRange.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/Operator.h"
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#include "llvm/IR/ValueHandle.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/Allocator.h"
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#include "llvm/Support/DataTypes.h"
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#include <map>
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namespace llvm {
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class APInt;
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class AssumptionCache;
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class Constant;
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class ConstantInt;
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class DominatorTree;
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class Type;
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class ScalarEvolution;
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class DataLayout;
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class TargetLibraryInfo;
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class LLVMContext;
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class Loop;
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class LoopInfo;
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class Operator;
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class SCEVUnknown;
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class SCEV;
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template<> struct FoldingSetTrait<SCEV>;
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/// SCEV - This class represents an analyzed expression in the program. These
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/// are opaque objects that the client is not allowed to do much with
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/// directly.
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///
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class SCEV : public FoldingSetNode {
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friend struct FoldingSetTrait<SCEV>;
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/// FastID - A reference to an Interned FoldingSetNodeID for this node.
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/// The ScalarEvolution's BumpPtrAllocator holds the data.
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FoldingSetNodeIDRef FastID;
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// The SCEV baseclass this node corresponds to
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const unsigned short SCEVType;
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protected:
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/// SubclassData - This field is initialized to zero and may be used in
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/// subclasses to store miscellaneous information.
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unsigned short SubclassData;
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private:
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SCEV(const SCEV &) = delete;
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void operator=(const SCEV &) = delete;
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public:
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/// NoWrapFlags are bitfield indices into SubclassData.
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///
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/// Add and Mul expressions may have no-unsigned-wrap <NUW> or
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/// no-signed-wrap <NSW> properties, which are derived from the IR
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/// operator. NSW is a misnomer that we use to mean no signed overflow or
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/// underflow.
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///
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/// AddRec expressions may have a no-self-wraparound <NW> property if, in
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/// the integer domain, abs(step) * max-iteration(loop) <=
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/// unsigned-max(bitwidth). This means that the recurrence will never reach
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/// its start value if the step is non-zero. Computing the same value on
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/// each iteration is not considered wrapping, and recurrences with step = 0
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/// are trivially <NW>. <NW> is independent of the sign of step and the
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/// value the add recurrence starts with.
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///
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/// Note that NUW and NSW are also valid properties of a recurrence, and
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/// either implies NW. For convenience, NW will be set for a recurrence
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/// whenever either NUW or NSW are set.
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enum NoWrapFlags { FlagAnyWrap = 0, // No guarantee.
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FlagNW = (1 << 0), // No self-wrap.
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FlagNUW = (1 << 1), // No unsigned wrap.
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FlagNSW = (1 << 2), // No signed wrap.
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NoWrapMask = (1 << 3) -1 };
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explicit SCEV(const FoldingSetNodeIDRef ID, unsigned SCEVTy) :
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FastID(ID), SCEVType(SCEVTy), SubclassData(0) {}
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unsigned getSCEVType() const { return SCEVType; }
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/// getType - Return the LLVM type of this SCEV expression.
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///
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Type *getType() const;
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/// isZero - Return true if the expression is a constant zero.
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///
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bool isZero() const;
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/// isOne - Return true if the expression is a constant one.
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///
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bool isOne() const;
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/// isAllOnesValue - Return true if the expression is a constant
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/// all-ones value.
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///
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bool isAllOnesValue() const;
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/// isNonConstantNegative - Return true if the specified scev is negated,
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/// but not a constant.
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bool isNonConstantNegative() const;
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/// print - Print out the internal representation of this scalar to the
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/// specified stream. This should really only be used for debugging
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/// purposes.
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void print(raw_ostream &OS) const;
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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/// dump - This method is used for debugging.
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///
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void dump() const;
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#endif
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};
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// Specialize FoldingSetTrait for SCEV to avoid needing to compute
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// temporary FoldingSetNodeID values.
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template<> struct FoldingSetTrait<SCEV> : DefaultFoldingSetTrait<SCEV> {
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static void Profile(const SCEV &X, FoldingSetNodeID& ID) {
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ID = X.FastID;
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}
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static bool Equals(const SCEV &X, const FoldingSetNodeID &ID,
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unsigned IDHash, FoldingSetNodeID &TempID) {
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return ID == X.FastID;
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}
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static unsigned ComputeHash(const SCEV &X, FoldingSetNodeID &TempID) {
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return X.FastID.ComputeHash();
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}
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};
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inline raw_ostream &operator<<(raw_ostream &OS, const SCEV &S) {
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S.print(OS);
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return OS;
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}
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/// SCEVCouldNotCompute - An object of this class is returned by queries that
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/// could not be answered. For example, if you ask for the number of
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/// iterations of a linked-list traversal loop, you will get one of these.
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/// None of the standard SCEV operations are valid on this class, it is just a
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/// marker.
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struct SCEVCouldNotCompute : public SCEV {
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SCEVCouldNotCompute();
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/// Methods for support type inquiry through isa, cast, and dyn_cast:
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static bool classof(const SCEV *S);
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};
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/// ScalarEvolution - This class is the main scalar evolution driver. Because
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/// client code (intentionally) can't do much with the SCEV objects directly,
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/// they must ask this class for services.
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///
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class ScalarEvolution : public FunctionPass {
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public:
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/// LoopDisposition - An enum describing the relationship between a
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/// SCEV and a loop.
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enum LoopDisposition {
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LoopVariant, ///< The SCEV is loop-variant (unknown).
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LoopInvariant, ///< The SCEV is loop-invariant.
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LoopComputable ///< The SCEV varies predictably with the loop.
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};
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/// BlockDisposition - An enum describing the relationship between a
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/// SCEV and a basic block.
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enum BlockDisposition {
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DoesNotDominateBlock, ///< The SCEV does not dominate the block.
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DominatesBlock, ///< The SCEV dominates the block.
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ProperlyDominatesBlock ///< The SCEV properly dominates the block.
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};
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/// Convenient NoWrapFlags manipulation that hides enum casts and is
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/// visible in the ScalarEvolution name space.
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static SCEV::NoWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT
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maskFlags(SCEV::NoWrapFlags Flags, int Mask) {
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return (SCEV::NoWrapFlags)(Flags & Mask);
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}
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static SCEV::NoWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT
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setFlags(SCEV::NoWrapFlags Flags, SCEV::NoWrapFlags OnFlags) {
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return (SCEV::NoWrapFlags)(Flags | OnFlags);
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}
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static SCEV::NoWrapFlags LLVM_ATTRIBUTE_UNUSED_RESULT
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clearFlags(SCEV::NoWrapFlags Flags, SCEV::NoWrapFlags OffFlags) {
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return (SCEV::NoWrapFlags)(Flags & ~OffFlags);
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}
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private:
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/// SCEVCallbackVH - A CallbackVH to arrange for ScalarEvolution to be
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/// notified whenever a Value is deleted.
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class SCEVCallbackVH : public CallbackVH {
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ScalarEvolution *SE;
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void deleted() override;
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void allUsesReplacedWith(Value *New) override;
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public:
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SCEVCallbackVH(Value *V, ScalarEvolution *SE = nullptr);
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};
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friend class SCEVCallbackVH;
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friend class SCEVExpander;
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friend class SCEVUnknown;
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/// F - The function we are analyzing.
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///
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Function *F;
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/// The tracker for @llvm.assume intrinsics in this function.
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AssumptionCache *AC;
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/// LI - The loop information for the function we are currently analyzing.
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///
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LoopInfo *LI;
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/// The DataLayout information for the target we are targeting.
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///
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const DataLayout *DL;
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/// TLI - The target library information for the target we are targeting.
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///
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TargetLibraryInfo *TLI;
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/// DT - The dominator tree.
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///
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DominatorTree *DT;
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/// CouldNotCompute - This SCEV is used to represent unknown trip
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/// counts and things.
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SCEVCouldNotCompute CouldNotCompute;
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/// ValueExprMapType - The typedef for ValueExprMap.
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///
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typedef DenseMap<SCEVCallbackVH, const SCEV *, DenseMapInfo<Value *> >
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ValueExprMapType;
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/// ValueExprMap - This is a cache of the values we have analyzed so far.
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///
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ValueExprMapType ValueExprMap;
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/// Mark predicate values currently being processed by isImpliedCond.
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DenseSet<Value*> PendingLoopPredicates;
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/// ExitLimit - Information about the number of loop iterations for which a
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/// loop exit's branch condition evaluates to the not-taken path. This is a
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/// temporary pair of exact and max expressions that are eventually
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/// summarized in ExitNotTakenInfo and BackedgeTakenInfo.
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struct ExitLimit {
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const SCEV *Exact;
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const SCEV *Max;
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/*implicit*/ ExitLimit(const SCEV *E) : Exact(E), Max(E) {}
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ExitLimit(const SCEV *E, const SCEV *M) : Exact(E), Max(M) {}
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/// hasAnyInfo - Test whether this ExitLimit contains any computed
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/// information, or whether it's all SCEVCouldNotCompute values.
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bool hasAnyInfo() const {
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return !isa<SCEVCouldNotCompute>(Exact) ||
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!isa<SCEVCouldNotCompute>(Max);
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}
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};
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/// ExitNotTakenInfo - Information about the number of times a particular
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/// loop exit may be reached before exiting the loop.
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struct ExitNotTakenInfo {
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AssertingVH<BasicBlock> ExitingBlock;
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const SCEV *ExactNotTaken;
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PointerIntPair<ExitNotTakenInfo*, 1> NextExit;
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ExitNotTakenInfo() : ExitingBlock(nullptr), ExactNotTaken(nullptr) {}
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/// isCompleteList - Return true if all loop exits are computable.
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bool isCompleteList() const {
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return NextExit.getInt() == 0;
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}
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void setIncomplete() { NextExit.setInt(1); }
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/// getNextExit - Return a pointer to the next exit's not-taken info.
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ExitNotTakenInfo *getNextExit() const {
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return NextExit.getPointer();
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}
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void setNextExit(ExitNotTakenInfo *ENT) { NextExit.setPointer(ENT); }
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};
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/// BackedgeTakenInfo - Information about the backedge-taken count
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/// of a loop. This currently includes an exact count and a maximum count.
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///
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class BackedgeTakenInfo {
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/// ExitNotTaken - A list of computable exits and their not-taken counts.
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/// Loops almost never have more than one computable exit.
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ExitNotTakenInfo ExitNotTaken;
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/// Max - An expression indicating the least maximum backedge-taken
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/// count of the loop that is known, or a SCEVCouldNotCompute.
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const SCEV *Max;
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public:
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BackedgeTakenInfo() : Max(nullptr) {}
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/// Initialize BackedgeTakenInfo from a list of exact exit counts.
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BackedgeTakenInfo(
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SmallVectorImpl< std::pair<BasicBlock *, const SCEV *> > &ExitCounts,
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bool Complete, const SCEV *MaxCount);
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/// hasAnyInfo - Test whether this BackedgeTakenInfo contains any
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/// computed information, or whether it's all SCEVCouldNotCompute
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/// values.
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bool hasAnyInfo() const {
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return ExitNotTaken.ExitingBlock || !isa<SCEVCouldNotCompute>(Max);
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}
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/// getExact - Return an expression indicating the exact backedge-taken
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/// count of the loop if it is known, or SCEVCouldNotCompute
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/// otherwise. This is the number of times the loop header can be
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/// guaranteed to execute, minus one.
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const SCEV *getExact(ScalarEvolution *SE) const;
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/// getExact - Return the number of times this loop exit may fall through
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/// to the back edge, or SCEVCouldNotCompute. The loop is guaranteed not
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/// to exit via this block before this number of iterations, but may exit
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/// via another block.
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const SCEV *getExact(BasicBlock *ExitingBlock, ScalarEvolution *SE) const;
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/// getMax - Get the max backedge taken count for the loop.
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const SCEV *getMax(ScalarEvolution *SE) const;
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/// Return true if any backedge taken count expressions refer to the given
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/// subexpression.
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bool hasOperand(const SCEV *S, ScalarEvolution *SE) const;
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/// clear - Invalidate this result and free associated memory.
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void clear();
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};
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/// BackedgeTakenCounts - Cache the backedge-taken count of the loops for
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/// this function as they are computed.
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DenseMap<const Loop*, BackedgeTakenInfo> BackedgeTakenCounts;
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/// ConstantEvolutionLoopExitValue - This map contains entries for all of
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/// the PHI instructions that we attempt to compute constant evolutions for.
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/// This allows us to avoid potentially expensive recomputation of these
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/// properties. An instruction maps to null if we are unable to compute its
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/// exit value.
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DenseMap<PHINode*, Constant*> ConstantEvolutionLoopExitValue;
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/// ValuesAtScopes - This map contains entries for all the expressions
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/// that we attempt to compute getSCEVAtScope information for, which can
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/// be expensive in extreme cases.
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DenseMap<const SCEV *,
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SmallVector<std::pair<const Loop *, const SCEV *>, 2> > ValuesAtScopes;
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/// LoopDispositions - Memoized computeLoopDisposition results.
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DenseMap<const SCEV *,
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SmallVector<PointerIntPair<const Loop *, 2, LoopDisposition>, 2>>
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LoopDispositions;
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/// computeLoopDisposition - Compute a LoopDisposition value.
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LoopDisposition computeLoopDisposition(const SCEV *S, const Loop *L);
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/// BlockDispositions - Memoized computeBlockDisposition results.
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DenseMap<
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const SCEV *,
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SmallVector<PointerIntPair<const BasicBlock *, 2, BlockDisposition>, 2>>
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BlockDispositions;
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/// computeBlockDisposition - Compute a BlockDisposition value.
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BlockDisposition computeBlockDisposition(const SCEV *S, const BasicBlock *BB);
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/// UnsignedRanges - Memoized results from getUnsignedRange
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DenseMap<const SCEV *, ConstantRange> UnsignedRanges;
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/// SignedRanges - Memoized results from getSignedRange
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DenseMap<const SCEV *, ConstantRange> SignedRanges;
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/// setUnsignedRange - Set the memoized unsigned range for the given SCEV.
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const ConstantRange &setUnsignedRange(const SCEV *S,
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const ConstantRange &CR) {
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std::pair<DenseMap<const SCEV *, ConstantRange>::iterator, bool> Pair =
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UnsignedRanges.insert(std::make_pair(S, CR));
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if (!Pair.second)
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Pair.first->second = CR;
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return Pair.first->second;
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}
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/// setUnsignedRange - Set the memoized signed range for the given SCEV.
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const ConstantRange &setSignedRange(const SCEV *S,
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const ConstantRange &CR) {
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std::pair<DenseMap<const SCEV *, ConstantRange>::iterator, bool> Pair =
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SignedRanges.insert(std::make_pair(S, CR));
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if (!Pair.second)
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Pair.first->second = CR;
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return Pair.first->second;
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}
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/// createSCEV - We know that there is no SCEV for the specified value.
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/// Analyze the expression.
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const SCEV *createSCEV(Value *V);
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/// createNodeForPHI - Provide the special handling we need to analyze PHI
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/// SCEVs.
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const SCEV *createNodeForPHI(PHINode *PN);
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/// createNodeForGEP - Provide the special handling we need to analyze GEP
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/// SCEVs.
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const SCEV *createNodeForGEP(GEPOperator *GEP);
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/// computeSCEVAtScope - Implementation code for getSCEVAtScope; called
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/// at most once for each SCEV+Loop pair.
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///
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const SCEV *computeSCEVAtScope(const SCEV *S, const Loop *L);
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/// ForgetSymbolicValue - This looks up computed SCEV values for all
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/// instructions that depend on the given instruction and removes them from
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/// the ValueExprMap map if they reference SymName. This is used during PHI
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/// resolution.
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void ForgetSymbolicName(Instruction *I, const SCEV *SymName);
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/// getBackedgeTakenInfo - Return the BackedgeTakenInfo for the given
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/// loop, lazily computing new values if the loop hasn't been analyzed
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/// yet.
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const BackedgeTakenInfo &getBackedgeTakenInfo(const Loop *L);
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/// ComputeBackedgeTakenCount - Compute the number of times the specified
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/// loop will iterate.
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BackedgeTakenInfo ComputeBackedgeTakenCount(const Loop *L);
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/// ComputeExitLimit - Compute the number of times the backedge of the
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/// specified loop will execute if it exits via the specified block.
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ExitLimit ComputeExitLimit(const Loop *L, BasicBlock *ExitingBlock);
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/// ComputeExitLimitFromCond - Compute the number of times the backedge of
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/// the specified loop will execute if its exit condition were a conditional
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/// branch of ExitCond, TBB, and FBB.
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ExitLimit ComputeExitLimitFromCond(const Loop *L,
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Value *ExitCond,
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BasicBlock *TBB,
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BasicBlock *FBB,
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bool IsSubExpr);
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/// ComputeExitLimitFromICmp - Compute the number of times the backedge of
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/// the specified loop will execute if its exit condition were a conditional
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/// branch of the ICmpInst ExitCond, TBB, and FBB.
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ExitLimit ComputeExitLimitFromICmp(const Loop *L,
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ICmpInst *ExitCond,
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BasicBlock *TBB,
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BasicBlock *FBB,
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bool IsSubExpr);
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/// ComputeExitLimitFromSingleExitSwitch - Compute the number of times the
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/// backedge of the specified loop will execute if its exit condition were a
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/// switch with a single exiting case to ExitingBB.
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ExitLimit
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ComputeExitLimitFromSingleExitSwitch(const Loop *L, SwitchInst *Switch,
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BasicBlock *ExitingBB, bool IsSubExpr);
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/// ComputeLoadConstantCompareExitLimit - Given an exit condition
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/// of 'icmp op load X, cst', try to see if we can compute the
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/// backedge-taken count.
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ExitLimit ComputeLoadConstantCompareExitLimit(LoadInst *LI,
|
|
Constant *RHS,
|
|
const Loop *L,
|
|
ICmpInst::Predicate p);
|
|
|
|
/// ComputeExitCountExhaustively - If the loop is known to execute a
|
|
/// constant number of times (the condition evolves only from constants),
|
|
/// try to evaluate a few iterations of the loop until we get the exit
|
|
/// condition gets a value of ExitWhen (true or false). If we cannot
|
|
/// evaluate the exit count of the loop, return CouldNotCompute.
|
|
const SCEV *ComputeExitCountExhaustively(const Loop *L,
|
|
Value *Cond,
|
|
bool ExitWhen);
|
|
|
|
/// HowFarToZero - Return the number of times an exit condition comparing
|
|
/// the specified value to zero will execute. If not computable, return
|
|
/// CouldNotCompute.
|
|
ExitLimit HowFarToZero(const SCEV *V, const Loop *L, bool IsSubExpr);
|
|
|
|
/// HowFarToNonZero - Return the number of times an exit condition checking
|
|
/// the specified value for nonzero will execute. If not computable, return
|
|
/// CouldNotCompute.
|
|
ExitLimit HowFarToNonZero(const SCEV *V, const Loop *L);
|
|
|
|
/// HowManyLessThans - Return the number of times an exit condition
|
|
/// containing the specified less-than comparison will execute. If not
|
|
/// computable, return CouldNotCompute. isSigned specifies whether the
|
|
/// less-than is signed.
|
|
ExitLimit HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
|
|
const Loop *L, bool isSigned, bool IsSubExpr);
|
|
ExitLimit HowManyGreaterThans(const SCEV *LHS, const SCEV *RHS,
|
|
const Loop *L, bool isSigned, bool IsSubExpr);
|
|
|
|
/// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB
|
|
/// (which may not be an immediate predecessor) which has exactly one
|
|
/// successor from which BB is reachable, or null if no such block is
|
|
/// found.
|
|
std::pair<BasicBlock *, BasicBlock *>
|
|
getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB);
|
|
|
|
/// isImpliedCond - Test whether the condition described by Pred, LHS, and
|
|
/// RHS is true whenever the given FoundCondValue value evaluates to true.
|
|
bool isImpliedCond(ICmpInst::Predicate Pred,
|
|
const SCEV *LHS, const SCEV *RHS,
|
|
Value *FoundCondValue,
|
|
bool Inverse);
|
|
|
|
/// isImpliedCondOperands - Test whether the condition described by Pred,
|
|
/// LHS, and RHS is true whenever the condition described by Pred, FoundLHS,
|
|
/// and FoundRHS is true.
|
|
bool isImpliedCondOperands(ICmpInst::Predicate Pred,
|
|
const SCEV *LHS, const SCEV *RHS,
|
|
const SCEV *FoundLHS, const SCEV *FoundRHS);
|
|
|
|
/// isImpliedCondOperandsHelper - Test whether the condition described by
|
|
/// Pred, LHS, and RHS is true whenever the condition described by Pred,
|
|
/// FoundLHS, and FoundRHS is true.
|
|
bool isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
|
|
const SCEV *LHS, const SCEV *RHS,
|
|
const SCEV *FoundLHS,
|
|
const SCEV *FoundRHS);
|
|
|
|
/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
|
|
/// in the header of its containing loop, we know the loop executes a
|
|
/// constant number of times, and the PHI node is just a recurrence
|
|
/// involving constants, fold it.
|
|
Constant *getConstantEvolutionLoopExitValue(PHINode *PN, const APInt& BEs,
|
|
const Loop *L);
|
|
|
|
/// isKnownPredicateWithRanges - Test if the given expression is known to
|
|
/// satisfy the condition described by Pred and the known constant ranges
|
|
/// of LHS and RHS.
|
|
///
|
|
bool isKnownPredicateWithRanges(ICmpInst::Predicate Pred,
|
|
const SCEV *LHS, const SCEV *RHS);
|
|
|
|
/// forgetMemoizedResults - Drop memoized information computed for S.
|
|
void forgetMemoizedResults(const SCEV *S);
|
|
|
|
/// Return false iff given SCEV contains a SCEVUnknown with NULL value-
|
|
/// pointer.
|
|
bool checkValidity(const SCEV *S) const;
|
|
|
|
public:
|
|
static char ID; // Pass identification, replacement for typeid
|
|
ScalarEvolution();
|
|
|
|
LLVMContext &getContext() const { return F->getContext(); }
|
|
|
|
/// isSCEVable - Test if values of the given type are analyzable within
|
|
/// the SCEV framework. This primarily includes integer types, and it
|
|
/// can optionally include pointer types if the ScalarEvolution class
|
|
/// has access to target-specific information.
|
|
bool isSCEVable(Type *Ty) const;
|
|
|
|
/// getTypeSizeInBits - Return the size in bits of the specified type,
|
|
/// for which isSCEVable must return true.
|
|
uint64_t getTypeSizeInBits(Type *Ty) const;
|
|
|
|
/// getEffectiveSCEVType - Return a type with the same bitwidth as
|
|
/// the given type and which represents how SCEV will treat the given
|
|
/// type, for which isSCEVable must return true. For pointer types,
|
|
/// this is the pointer-sized integer type.
|
|
Type *getEffectiveSCEVType(Type *Ty) const;
|
|
|
|
/// getSCEV - Return a SCEV expression for the full generality of the
|
|
/// specified expression.
|
|
const SCEV *getSCEV(Value *V);
|
|
|
|
const SCEV *getConstant(ConstantInt *V);
|
|
const SCEV *getConstant(const APInt& Val);
|
|
const SCEV *getConstant(Type *Ty, uint64_t V, bool isSigned = false);
|
|
const SCEV *getTruncateExpr(const SCEV *Op, Type *Ty);
|
|
const SCEV *getZeroExtendExpr(const SCEV *Op, Type *Ty);
|
|
const SCEV *getSignExtendExpr(const SCEV *Op, Type *Ty);
|
|
const SCEV *getAnyExtendExpr(const SCEV *Op, Type *Ty);
|
|
const SCEV *getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
|
|
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap);
|
|
const SCEV *getAddExpr(const SCEV *LHS, const SCEV *RHS,
|
|
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap) {
|
|
SmallVector<const SCEV *, 2> Ops;
|
|
Ops.push_back(LHS);
|
|
Ops.push_back(RHS);
|
|
return getAddExpr(Ops, Flags);
|
|
}
|
|
const SCEV *getAddExpr(const SCEV *Op0, const SCEV *Op1, const SCEV *Op2,
|
|
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap) {
|
|
SmallVector<const SCEV *, 3> Ops;
|
|
Ops.push_back(Op0);
|
|
Ops.push_back(Op1);
|
|
Ops.push_back(Op2);
|
|
return getAddExpr(Ops, Flags);
|
|
}
|
|
const SCEV *getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
|
|
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap);
|
|
const SCEV *getMulExpr(const SCEV *LHS, const SCEV *RHS,
|
|
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap)
|
|
{
|
|
SmallVector<const SCEV *, 2> Ops;
|
|
Ops.push_back(LHS);
|
|
Ops.push_back(RHS);
|
|
return getMulExpr(Ops, Flags);
|
|
}
|
|
const SCEV *getMulExpr(const SCEV *Op0, const SCEV *Op1, const SCEV *Op2,
|
|
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap) {
|
|
SmallVector<const SCEV *, 3> Ops;
|
|
Ops.push_back(Op0);
|
|
Ops.push_back(Op1);
|
|
Ops.push_back(Op2);
|
|
return getMulExpr(Ops, Flags);
|
|
}
|
|
const SCEV *getUDivExpr(const SCEV *LHS, const SCEV *RHS);
|
|
const SCEV *getUDivExactExpr(const SCEV *LHS, const SCEV *RHS);
|
|
const SCEV *getAddRecExpr(const SCEV *Start, const SCEV *Step,
|
|
const Loop *L, SCEV::NoWrapFlags Flags);
|
|
const SCEV *getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
|
|
const Loop *L, SCEV::NoWrapFlags Flags);
|
|
const SCEV *getAddRecExpr(const SmallVectorImpl<const SCEV *> &Operands,
|
|
const Loop *L, SCEV::NoWrapFlags Flags) {
|
|
SmallVector<const SCEV *, 4> NewOp(Operands.begin(), Operands.end());
|
|
return getAddRecExpr(NewOp, L, Flags);
|
|
}
|
|
const SCEV *getSMaxExpr(const SCEV *LHS, const SCEV *RHS);
|
|
const SCEV *getSMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
|
|
const SCEV *getUMaxExpr(const SCEV *LHS, const SCEV *RHS);
|
|
const SCEV *getUMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
|
|
const SCEV *getSMinExpr(const SCEV *LHS, const SCEV *RHS);
|
|
const SCEV *getUMinExpr(const SCEV *LHS, const SCEV *RHS);
|
|
const SCEV *getUnknown(Value *V);
|
|
const SCEV *getCouldNotCompute();
|
|
|
|
/// getSizeOfExpr - Return an expression for sizeof AllocTy that is type
|
|
/// IntTy
|
|
///
|
|
const SCEV *getSizeOfExpr(Type *IntTy, Type *AllocTy);
|
|
|
|
/// getOffsetOfExpr - Return an expression for offsetof on the given field
|
|
/// with type IntTy
|
|
///
|
|
const SCEV *getOffsetOfExpr(Type *IntTy, StructType *STy, unsigned FieldNo);
|
|
|
|
/// getNegativeSCEV - Return the SCEV object corresponding to -V.
|
|
///
|
|
const SCEV *getNegativeSCEV(const SCEV *V);
|
|
|
|
/// getNotSCEV - Return the SCEV object corresponding to ~V.
|
|
///
|
|
const SCEV *getNotSCEV(const SCEV *V);
|
|
|
|
/// getMinusSCEV - Return LHS-RHS. Minus is represented in SCEV as A+B*-1.
|
|
const SCEV *getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
|
|
SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap);
|
|
|
|
/// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion
|
|
/// of the input value to the specified type. If the type must be
|
|
/// extended, it is zero extended.
|
|
const SCEV *getTruncateOrZeroExtend(const SCEV *V, Type *Ty);
|
|
|
|
/// getTruncateOrSignExtend - Return a SCEV corresponding to a conversion
|
|
/// of the input value to the specified type. If the type must be
|
|
/// extended, it is sign extended.
|
|
const SCEV *getTruncateOrSignExtend(const SCEV *V, Type *Ty);
|
|
|
|
/// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of
|
|
/// the input value to the specified type. If the type must be extended,
|
|
/// it is zero extended. The conversion must not be narrowing.
|
|
const SCEV *getNoopOrZeroExtend(const SCEV *V, Type *Ty);
|
|
|
|
/// getNoopOrSignExtend - Return a SCEV corresponding to a conversion of
|
|
/// the input value to the specified type. If the type must be extended,
|
|
/// it is sign extended. The conversion must not be narrowing.
|
|
const SCEV *getNoopOrSignExtend(const SCEV *V, Type *Ty);
|
|
|
|
/// getNoopOrAnyExtend - Return a SCEV corresponding to a conversion of
|
|
/// the input value to the specified type. If the type must be extended,
|
|
/// it is extended with unspecified bits. The conversion must not be
|
|
/// narrowing.
|
|
const SCEV *getNoopOrAnyExtend(const SCEV *V, Type *Ty);
|
|
|
|
/// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the
|
|
/// input value to the specified type. The conversion must not be
|
|
/// widening.
|
|
const SCEV *getTruncateOrNoop(const SCEV *V, Type *Ty);
|
|
|
|
/// getUMaxFromMismatchedTypes - Promote the operands to the wider of
|
|
/// the types using zero-extension, and then perform a umax operation
|
|
/// with them.
|
|
const SCEV *getUMaxFromMismatchedTypes(const SCEV *LHS,
|
|
const SCEV *RHS);
|
|
|
|
/// getUMinFromMismatchedTypes - Promote the operands to the wider of
|
|
/// the types using zero-extension, and then perform a umin operation
|
|
/// with them.
|
|
const SCEV *getUMinFromMismatchedTypes(const SCEV *LHS,
|
|
const SCEV *RHS);
|
|
|
|
/// getPointerBase - Transitively follow the chain of pointer-type operands
|
|
/// until reaching a SCEV that does not have a single pointer operand. This
|
|
/// returns a SCEVUnknown pointer for well-formed pointer-type expressions,
|
|
/// but corner cases do exist.
|
|
const SCEV *getPointerBase(const SCEV *V);
|
|
|
|
/// getSCEVAtScope - Return a SCEV expression for the specified value
|
|
/// at the specified scope in the program. The L value specifies a loop
|
|
/// nest to evaluate the expression at, where null is the top-level or a
|
|
/// specified loop is immediately inside of the loop.
|
|
///
|
|
/// This method can be used to compute the exit value for a variable defined
|
|
/// in a loop by querying what the value will hold in the parent loop.
|
|
///
|
|
/// In the case that a relevant loop exit value cannot be computed, the
|
|
/// original value V is returned.
|
|
const SCEV *getSCEVAtScope(const SCEV *S, const Loop *L);
|
|
|
|
/// getSCEVAtScope - This is a convenience function which does
|
|
/// getSCEVAtScope(getSCEV(V), L).
|
|
const SCEV *getSCEVAtScope(Value *V, const Loop *L);
|
|
|
|
/// isLoopEntryGuardedByCond - Test whether entry to the loop is protected
|
|
/// by a conditional between LHS and RHS. This is used to help avoid max
|
|
/// expressions in loop trip counts, and to eliminate casts.
|
|
bool isLoopEntryGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
|
|
const SCEV *LHS, const SCEV *RHS);
|
|
|
|
/// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
|
|
/// protected by a conditional between LHS and RHS. This is used to
|
|
/// to eliminate casts.
|
|
bool isLoopBackedgeGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
|
|
const SCEV *LHS, const SCEV *RHS);
|
|
|
|
/// \brief Returns the maximum trip count of the loop if it is a single-exit
|
|
/// loop and we can compute a small maximum for that loop.
|
|
///
|
|
/// Implemented in terms of the \c getSmallConstantTripCount overload with
|
|
/// the single exiting block passed to it. See that routine for details.
|
|
unsigned getSmallConstantTripCount(Loop *L);
|
|
|
|
/// getSmallConstantTripCount - Returns the maximum trip count of this loop
|
|
/// as a normal unsigned value. Returns 0 if the trip count is unknown or
|
|
/// not constant. This "trip count" assumes that control exits via
|
|
/// ExitingBlock. More precisely, it is the number of times that control may
|
|
/// reach ExitingBlock before taking the branch. For loops with multiple
|
|
/// exits, it may not be the number times that the loop header executes if
|
|
/// the loop exits prematurely via another branch.
|
|
unsigned getSmallConstantTripCount(Loop *L, BasicBlock *ExitingBlock);
|
|
|
|
/// \brief Returns the largest constant divisor of the trip count of the
|
|
/// loop if it is a single-exit loop and we can compute a small maximum for
|
|
/// that loop.
|
|
///
|
|
/// Implemented in terms of the \c getSmallConstantTripMultiple overload with
|
|
/// the single exiting block passed to it. See that routine for details.
|
|
unsigned getSmallConstantTripMultiple(Loop *L);
|
|
|
|
/// getSmallConstantTripMultiple - Returns the largest constant divisor of
|
|
/// the trip count of this loop as a normal unsigned value, if
|
|
/// possible. This means that the actual trip count is always a multiple of
|
|
/// the returned value (don't forget the trip count could very well be zero
|
|
/// as well!). As explained in the comments for getSmallConstantTripCount,
|
|
/// this assumes that control exits the loop via ExitingBlock.
|
|
unsigned getSmallConstantTripMultiple(Loop *L, BasicBlock *ExitingBlock);
|
|
|
|
// getExitCount - Get the expression for the number of loop iterations for
|
|
// which this loop is guaranteed not to exit via ExitingBlock. Otherwise
|
|
// return SCEVCouldNotCompute.
|
|
const SCEV *getExitCount(Loop *L, BasicBlock *ExitingBlock);
|
|
|
|
/// getBackedgeTakenCount - If the specified loop has a predictable
|
|
/// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
|
|
/// object. The backedge-taken count is the number of times the loop header
|
|
/// will be branched to from within the loop. This is one less than the
|
|
/// trip count of the loop, since it doesn't count the first iteration,
|
|
/// when the header is branched to from outside the loop.
|
|
///
|
|
/// Note that it is not valid to call this method on a loop without a
|
|
/// loop-invariant backedge-taken count (see
|
|
/// hasLoopInvariantBackedgeTakenCount).
|
|
///
|
|
const SCEV *getBackedgeTakenCount(const Loop *L);
|
|
|
|
/// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except
|
|
/// return the least SCEV value that is known never to be less than the
|
|
/// actual backedge taken count.
|
|
const SCEV *getMaxBackedgeTakenCount(const Loop *L);
|
|
|
|
/// hasLoopInvariantBackedgeTakenCount - Return true if the specified loop
|
|
/// has an analyzable loop-invariant backedge-taken count.
|
|
bool hasLoopInvariantBackedgeTakenCount(const Loop *L);
|
|
|
|
/// forgetLoop - This method should be called by the client when it has
|
|
/// changed a loop in a way that may effect ScalarEvolution's ability to
|
|
/// compute a trip count, or if the loop is deleted. This call is
|
|
/// potentially expensive for large loop bodies.
|
|
void forgetLoop(const Loop *L);
|
|
|
|
/// forgetValue - This method should be called by the client when it has
|
|
/// changed a value in a way that may effect its value, or which may
|
|
/// disconnect it from a def-use chain linking it to a loop.
|
|
void forgetValue(Value *V);
|
|
|
|
/// \brief Called when the client has changed the disposition of values in
|
|
/// this loop.
|
|
///
|
|
/// We don't have a way to invalidate per-loop dispositions. Clear and
|
|
/// recompute is simpler.
|
|
void forgetLoopDispositions(const Loop *L) { LoopDispositions.clear(); }
|
|
|
|
/// GetMinTrailingZeros - Determine the minimum number of zero bits that S
|
|
/// is guaranteed to end in (at every loop iteration). It is, at the same
|
|
/// time, the minimum number of times S is divisible by 2. For example,
|
|
/// given {4,+,8} it returns 2. If S is guaranteed to be 0, it returns the
|
|
/// bitwidth of S.
|
|
uint32_t GetMinTrailingZeros(const SCEV *S);
|
|
|
|
/// getUnsignedRange - Determine the unsigned range for a particular SCEV.
|
|
///
|
|
ConstantRange getUnsignedRange(const SCEV *S);
|
|
|
|
/// getSignedRange - Determine the signed range for a particular SCEV.
|
|
///
|
|
ConstantRange getSignedRange(const SCEV *S);
|
|
|
|
/// isKnownNegative - Test if the given expression is known to be negative.
|
|
///
|
|
bool isKnownNegative(const SCEV *S);
|
|
|
|
/// isKnownPositive - Test if the given expression is known to be positive.
|
|
///
|
|
bool isKnownPositive(const SCEV *S);
|
|
|
|
/// isKnownNonNegative - Test if the given expression is known to be
|
|
/// non-negative.
|
|
///
|
|
bool isKnownNonNegative(const SCEV *S);
|
|
|
|
/// isKnownNonPositive - Test if the given expression is known to be
|
|
/// non-positive.
|
|
///
|
|
bool isKnownNonPositive(const SCEV *S);
|
|
|
|
/// isKnownNonZero - Test if the given expression is known to be
|
|
/// non-zero.
|
|
///
|
|
bool isKnownNonZero(const SCEV *S);
|
|
|
|
/// isKnownPredicate - Test if the given expression is known to satisfy
|
|
/// the condition described by Pred, LHS, and RHS.
|
|
///
|
|
bool isKnownPredicate(ICmpInst::Predicate Pred,
|
|
const SCEV *LHS, const SCEV *RHS);
|
|
|
|
/// SimplifyICmpOperands - Simplify LHS and RHS in a comparison with
|
|
/// predicate Pred. Return true iff any changes were made. If the
|
|
/// operands are provably equal or unequal, LHS and RHS are set to
|
|
/// the same value and Pred is set to either ICMP_EQ or ICMP_NE.
|
|
///
|
|
bool SimplifyICmpOperands(ICmpInst::Predicate &Pred,
|
|
const SCEV *&LHS,
|
|
const SCEV *&RHS,
|
|
unsigned Depth = 0);
|
|
|
|
/// getLoopDisposition - Return the "disposition" of the given SCEV with
|
|
/// respect to the given loop.
|
|
LoopDisposition getLoopDisposition(const SCEV *S, const Loop *L);
|
|
|
|
/// isLoopInvariant - Return true if the value of the given SCEV is
|
|
/// unchanging in the specified loop.
|
|
bool isLoopInvariant(const SCEV *S, const Loop *L);
|
|
|
|
/// hasComputableLoopEvolution - Return true if the given SCEV changes value
|
|
/// in a known way in the specified loop. This property being true implies
|
|
/// that the value is variant in the loop AND that we can emit an expression
|
|
/// to compute the value of the expression at any particular loop iteration.
|
|
bool hasComputableLoopEvolution(const SCEV *S, const Loop *L);
|
|
|
|
/// getLoopDisposition - Return the "disposition" of the given SCEV with
|
|
/// respect to the given block.
|
|
BlockDisposition getBlockDisposition(const SCEV *S, const BasicBlock *BB);
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/// dominates - Return true if elements that makes up the given SCEV
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/// dominate the specified basic block.
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bool dominates(const SCEV *S, const BasicBlock *BB);
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/// properlyDominates - Return true if elements that makes up the given SCEV
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/// properly dominate the specified basic block.
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bool properlyDominates(const SCEV *S, const BasicBlock *BB);
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/// hasOperand - Test whether the given SCEV has Op as a direct or
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/// indirect operand.
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bool hasOperand(const SCEV *S, const SCEV *Op) const;
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/// Return the size of an element read or written by Inst.
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const SCEV *getElementSize(Instruction *Inst);
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/// Compute the array dimensions Sizes from the set of Terms extracted from
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/// the memory access function of this SCEVAddRecExpr.
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void findArrayDimensions(SmallVectorImpl<const SCEV *> &Terms,
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SmallVectorImpl<const SCEV *> &Sizes,
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const SCEV *ElementSize) const;
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bool runOnFunction(Function &F) override;
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void releaseMemory() override;
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void getAnalysisUsage(AnalysisUsage &AU) const override;
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void print(raw_ostream &OS, const Module* = nullptr) const override;
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void verifyAnalysis() const override;
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private:
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/// Compute the backedge taken count knowing the interval difference, the
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/// stride and presence of the equality in the comparison.
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const SCEV *computeBECount(const SCEV *Delta, const SCEV *Stride,
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bool Equality);
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/// Verify if an linear IV with positive stride can overflow when in a
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/// less-than comparison, knowing the invariant term of the comparison,
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/// the stride and the knowledge of NSW/NUW flags on the recurrence.
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bool doesIVOverflowOnLT(const SCEV *RHS, const SCEV *Stride,
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bool IsSigned, bool NoWrap);
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/// Verify if an linear IV with negative stride can overflow when in a
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/// greater-than comparison, knowing the invariant term of the comparison,
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/// the stride and the knowledge of NSW/NUW flags on the recurrence.
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bool doesIVOverflowOnGT(const SCEV *RHS, const SCEV *Stride,
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bool IsSigned, bool NoWrap);
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private:
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FoldingSet<SCEV> UniqueSCEVs;
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BumpPtrAllocator SCEVAllocator;
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/// FirstUnknown - The head of a linked list of all SCEVUnknown
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/// values that have been allocated. This is used by releaseMemory
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/// to locate them all and call their destructors.
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SCEVUnknown *FirstUnknown;
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};
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}
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#endif
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