VPlanTransforms.cpp revision 360784 
1//===-- VPlanTransforms.cpp - Utility VPlan to VPlan transforms -----------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8///
9/// \file
10/// This file implements a set of utility VPlan to VPlan transformations.
11///
12//===----------------------------------------------------------------------===//
13
14#include "VPlanTransforms.h"
15#include "llvm/ADT/PostOrderIterator.h"
16
17using namespace llvm;
18
19void VPlanTransforms::VPInstructionsToVPRecipes(
20    Loop *OrigLoop, VPlanPtr &Plan,
21    LoopVectorizationLegality::InductionList *Inductions,
22    SmallPtrSetImpl<Instruction *> &DeadInstructions) {
23
24  auto *TopRegion = cast<VPRegionBlock>(Plan->getEntry());
25  ReversePostOrderTraversal<VPBlockBase *> RPOT(TopRegion->getEntry());
26
27  // Condition bit VPValues get deleted during transformation to VPRecipes.
28  // Create new VPValues and save away as condition bits. These will be deleted
29  // after finalizing the vector IR basic blocks.
30  for (VPBlockBase *Base : RPOT) {
31    VPBasicBlock *VPBB = Base->getEntryBasicBlock();
32    if (auto *CondBit = VPBB->getCondBit()) {
33      auto *NCondBit = new VPValue(CondBit->getUnderlyingValue());
34      VPBB->setCondBit(NCondBit);
35      Plan->addCBV(NCondBit);
36    }
37  }
38  for (VPBlockBase *Base : RPOT) {
39    // Do not widen instructions in pre-header and exit blocks.
40    if (Base->getNumPredecessors() == 0 || Base->getNumSuccessors() == 0)
41      continue;
42
43    VPBasicBlock *VPBB = Base->getEntryBasicBlock();
44    VPRecipeBase *LastRecipe = nullptr;
45    // Introduce each ingredient into VPlan.
46    for (auto I = VPBB->begin(), E = VPBB->end(); I != E;) {
47      VPRecipeBase *Ingredient = &*I++;
48      // Can only handle VPInstructions.
49      VPInstruction *VPInst = cast<VPInstruction>(Ingredient);
50      Instruction *Inst = cast<Instruction>(VPInst->getUnderlyingValue());
51      if (DeadInstructions.count(Inst)) {
52        Ingredient->eraseFromParent();
53        continue;
54      }
55
56      VPRecipeBase *NewRecipe = nullptr;
57      // Create VPWidenMemoryInstructionRecipe for loads and stores.
58      if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst))
59        NewRecipe = new VPWidenMemoryInstructionRecipe(
60            *Inst, Plan->getOrAddVPValue(getLoadStorePointerOperand(Inst)),
61            nullptr /*Mask*/);
62      else if (PHINode *Phi = dyn_cast<PHINode>(Inst)) {
63        InductionDescriptor II = Inductions->lookup(Phi);
64        if (II.getKind() == InductionDescriptor::IK_IntInduction ||
65            II.getKind() == InductionDescriptor::IK_FpInduction) {
66          NewRecipe = new VPWidenIntOrFpInductionRecipe(Phi);
67        } else
68          NewRecipe = new VPWidenPHIRecipe(Phi);
69      } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
70        NewRecipe = new VPWidenGEPRecipe(GEP, OrigLoop);
71      } else {
72        // If the last recipe is a VPWidenRecipe, add Inst to it instead of
73        // creating a new recipe.
74        if (VPWidenRecipe *WidenRecipe =
75                dyn_cast_or_null<VPWidenRecipe>(LastRecipe)) {
76          WidenRecipe->appendInstruction(Inst);
77          Ingredient->eraseFromParent();
78          continue;
79        }
80        NewRecipe = new VPWidenRecipe(Inst);
81      }
82
83      NewRecipe->insertBefore(Ingredient);
84      LastRecipe = NewRecipe;
85      Ingredient->eraseFromParent();
86    }
87  }
88}
89