VPlanTransforms.cpp | Explore in Territory

//===-- VPlanTransforms.cpp - Utility VPlan to VPlan transforms -----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file implements a set of utility VPlan to VPlan transformations.
///
//===----------------------------------------------------------------------===//

#include "VPlanTransforms.h"
#include "VPRecipeBuilder.h"
#include "VPlan.h"
#include "VPlanAnalysis.h"
#include "VPlanCFG.h"
#include "VPlanDominatorTree.h"
#include "VPlanPatternMatch.h"
#include "VPlanUtils.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/ScopeExit.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/TypeSwitch.h"
#include "llvm/Analysis/IVDescriptors.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/PatternMatch.h"

usingnamespacellvm;

void VPlanTransforms::VPInstructionsToVPRecipes(
    VPlanPtr &Plan,
    function_ref<const InductionDescriptor *(PHINode *)>
        GetIntOrFpInductionDescriptor,
    ScalarEvolution &SE, const TargetLibraryInfo &TLI) { … }

static bool sinkScalarOperands(VPlan &Plan) { … }

/// If \p R is a region with a VPBranchOnMaskRecipe in the entry block, return
/// the mask.
VPValue *getPredicatedMask(VPRegionBlock *R) { … }

/// If \p R is a triangle region, return the 'then' block of the triangle.
static VPBasicBlock *getPredicatedThenBlock(VPRegionBlock *R) { … }

// Merge replicate regions in their successor region, if a replicate region
// is connected to a successor replicate region with the same predicate by a
// single, empty VPBasicBlock.
static bool mergeReplicateRegionsIntoSuccessors(VPlan &Plan) { … }

static VPRegionBlock *createReplicateRegion(VPReplicateRecipe *PredRecipe,
                                            VPlan &Plan) { … }

static void addReplicateRegions(VPlan &Plan) { … }

/// Remove redundant VPBasicBlocks by merging them into their predecessor if
/// the predecessor has a single successor.
static bool mergeBlocksIntoPredecessors(VPlan &Plan) { … }

void VPlanTransforms::createAndOptimizeReplicateRegions(VPlan &Plan) { … }

/// Remove redundant casts of inductions.
///
/// Such redundant casts are casts of induction variables that can be ignored,
/// because we already proved that the casted phi is equal to the uncasted phi
/// in the vectorized loop. There is no need to vectorize the cast - the same
/// value can be used for both the phi and casts in the vector loop.
static void removeRedundantInductionCasts(VPlan &Plan) { … }

/// Try to replace VPWidenCanonicalIVRecipes with a widened canonical IV
/// recipe, if it exists.
static void removeRedundantCanonicalIVs(VPlan &Plan) { … }

/// Returns true if \p R is dead and can be removed.
static bool isDeadRecipe(VPRecipeBase &R) { … }

void VPlanTransforms::removeDeadRecipes(VPlan &Plan) { … }

static VPScalarIVStepsRecipe *
createScalarIVSteps(VPlan &Plan, InductionDescriptor::InductionKind Kind,
                    Instruction::BinaryOps InductionOpcode,
                    FPMathOperator *FPBinOp, Instruction *TruncI,
                    VPValue *StartV, VPValue *Step, VPBuilder &Builder) { … }

/// Legalize VPWidenPointerInductionRecipe, by replacing it with a PtrAdd
/// (IndStart, ScalarIVSteps (0, Step)) if only its scalar values are used, as
/// VPWidenPointerInductionRecipe will generate vectors only. If some users
/// require vectors while other require scalars, the scalar uses need to extract
/// the scalars from the generated vectors (Note that this is different to how
/// int/fp inductions are handled). Also optimize VPWidenIntOrFpInductionRecipe,
/// if any of its users needs scalar values, by providing them scalar steps
/// built on the canonical scalar IV and update the original IV's users. This is
/// an optional optimization to reduce the needs of vector extracts.
static void legalizeAndOptimizeInductions(VPlan &Plan) { … }

/// Remove redundant EpxandSCEVRecipes in \p Plan's entry block by replacing
/// them with already existing recipes expanding the same SCEV expression.
static void removeRedundantExpandSCEVRecipes(VPlan &Plan) { … }

static void recursivelyDeleteDeadRecipes(VPValue *V) { … }

void VPlanTransforms::optimizeForVFAndUF(VPlan &Plan, ElementCount BestVF,
                                         unsigned BestUF,
                                         PredicatedScalarEvolution &PSE) { … }

/// Sink users of \p FOR after the recipe defining the previous value \p
/// Previous of the recurrence. \returns true if all users of \p FOR could be
/// re-arranged as needed or false if it is not possible.
static bool
sinkRecurrenceUsersAfterPrevious(VPFirstOrderRecurrencePHIRecipe *FOR,
                                 VPRecipeBase *Previous,
                                 VPDominatorTree &VPDT) { … }

bool VPlanTransforms::adjustFixedOrderRecurrences(VPlan &Plan,
                                                  VPBuilder &LoopBuilder) { … }

static SmallVector<VPUser *> collectUsersRecursively(VPValue *V) { … }

void VPlanTransforms::clearReductionWrapFlags(VPlan &Plan) { … }

/// Try to simplify recipe \p R.
static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) { … }

/// Move loop-invariant recipes out of the vector loop region in \p Plan.
static void licm(VPlan &Plan) { … }

/// Try to simplify the recipes in \p Plan.
static void simplifyRecipes(VPlan &Plan) { … }

void VPlanTransforms::truncateToMinimalBitwidths(
    VPlan &Plan, const MapVector<Instruction *, uint64_t> &MinBWs) { … }

void VPlanTransforms::optimize(VPlan &Plan) { … }

// Add a VPActiveLaneMaskPHIRecipe and related recipes to \p Plan and replace
// the loop terminator with a branch-on-cond recipe with the negated
// active-lane-mask as operand. Note that this turns the loop into an
// uncountable one. Only the existing terminator is replaced, all other existing
// recipes/users remain unchanged, except for poison-generating flags being
// dropped from the canonical IV increment. Return the created
// VPActiveLaneMaskPHIRecipe.
//
// The function uses the following definitions:
//
//  %TripCount = DataWithControlFlowWithoutRuntimeCheck ?
//    calculate-trip-count-minus-VF (original TC) : original TC
//  %IncrementValue = DataWithControlFlowWithoutRuntimeCheck ?
//     CanonicalIVPhi : CanonicalIVIncrement
//  %StartV is the canonical induction start value.
//
// The function adds the following recipes:
//
// vector.ph:
//   %TripCount = calculate-trip-count-minus-VF (original TC)
//       [if DataWithControlFlowWithoutRuntimeCheck]
//   %EntryInc = canonical-iv-increment-for-part %StartV
//   %EntryALM = active-lane-mask %EntryInc, %TripCount
//
// vector.body:
//   ...
//   %P = active-lane-mask-phi [ %EntryALM, %vector.ph ], [ %ALM, %vector.body ]
//   ...
//   %InLoopInc = canonical-iv-increment-for-part %IncrementValue
//   %ALM = active-lane-mask %InLoopInc, TripCount
//   %Negated = Not %ALM
//   branch-on-cond %Negated
//
static VPActiveLaneMaskPHIRecipe *addVPLaneMaskPhiAndUpdateExitBranch(
    VPlan &Plan, bool DataAndControlFlowWithoutRuntimeCheck) { … }

/// Collect all VPValues representing a header mask through the (ICMP_ULE,
/// WideCanonicalIV, backedge-taken-count) pattern.
/// TODO: Introduce explicit recipe for header-mask instead of searching
/// for the header-mask pattern manually.
static SmallVector<VPValue *> collectAllHeaderMasks(VPlan &Plan) { … }

void VPlanTransforms::addActiveLaneMask(
    VPlan &Plan, bool UseActiveLaneMaskForControlFlow,
    bool DataAndControlFlowWithoutRuntimeCheck) { … }

/// Replace recipes with their EVL variants.
static void transformRecipestoEVLRecipes(VPlan &Plan, VPValue &EVL) { … }

/// Add a VPEVLBasedIVPHIRecipe and related recipes to \p Plan and
/// replaces all uses except the canonical IV increment of
/// VPCanonicalIVPHIRecipe with a VPEVLBasedIVPHIRecipe. VPCanonicalIVPHIRecipe
/// is used only for loop iterations counting after this transformation.
///
/// The function uses the following definitions:
///  %StartV is the canonical induction start value.
///
/// The function adds the following recipes:
///
/// vector.ph:
/// ...
///
/// vector.body:
/// ...
/// %EVLPhi = EXPLICIT-VECTOR-LENGTH-BASED-IV-PHI [ %StartV, %vector.ph ],
///                                               [ %NextEVLIV, %vector.body ]
/// %AVL = sub original TC, %EVLPhi
/// %VPEVL = EXPLICIT-VECTOR-LENGTH %AVL
/// ...
/// %NextEVLIV = add IVSize (cast i32 %VPEVVL to IVSize), %EVLPhi
/// ...
///
bool VPlanTransforms::tryAddExplicitVectorLength(VPlan &Plan) { … }

void VPlanTransforms::dropPoisonGeneratingRecipes(
    VPlan &Plan, function_ref<bool(BasicBlock *)> BlockNeedsPredication) { … }

void VPlanTransforms::createInterleaveGroups(
    VPlan &Plan,
    const SmallPtrSetImpl<const InterleaveGroup<Instruction> *>
        &InterleaveGroups,
    VPRecipeBuilder &RecipeBuilder, bool ScalarEpilogueAllowed) { … }
llvm/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
