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 
17 using namespace llvm;
18 
19 void 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     // Introduce each ingredient into VPlan.
45     for (auto I = VPBB->begin(), E = VPBB->end(); I != E;) {
46       VPRecipeBase *Ingredient = &*I++;
47       // Can only handle VPInstructions.
48       VPInstruction *VPInst = cast<VPInstruction>(Ingredient);
49       Instruction *Inst = cast<Instruction>(VPInst->getUnderlyingValue());
50       if (DeadInstructions.count(Inst)) {
51         VPValue DummyValue;
52         VPInst->replaceAllUsesWith(&DummyValue);
53         Ingredient->eraseFromParent();
54         continue;
55       }
56 
57       VPRecipeBase *NewRecipe = nullptr;
58       // Create VPWidenMemoryInstructionRecipe for loads and stores.
59       if (LoadInst *Load = dyn_cast<LoadInst>(Inst))
60         NewRecipe = new VPWidenMemoryInstructionRecipe(
61             *Load, Plan->getOrAddVPValue(getLoadStorePointerOperand(Inst)),
62             nullptr /*Mask*/);
63       else if (StoreInst *Store = dyn_cast<StoreInst>(Inst))
64         NewRecipe = new VPWidenMemoryInstructionRecipe(
65             *Store, Plan->getOrAddVPValue(getLoadStorePointerOperand(Inst)),
66             Plan->getOrAddVPValue(Store->getValueOperand()), nullptr /*Mask*/);
67       else if (PHINode *Phi = dyn_cast<PHINode>(Inst)) {
68         InductionDescriptor II = Inductions.lookup(Phi);
69         if (II.getKind() == InductionDescriptor::IK_IntInduction ||
70             II.getKind() == InductionDescriptor::IK_FpInduction) {
71           VPValue *Start = Plan->getOrAddVPValue(II.getStartValue());
72           NewRecipe = new VPWidenIntOrFpInductionRecipe(Phi, Start);
73         } else
74           NewRecipe = new VPWidenPHIRecipe(Phi);
75       } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
76         NewRecipe = new VPWidenGEPRecipe(
77             GEP, Plan->mapToVPValues(GEP->operands()), OrigLoop);
78       } else
79         NewRecipe =
80             new VPWidenRecipe(*Inst, Plan->mapToVPValues(Inst->operands()));
81 
82       NewRecipe->insertBefore(Ingredient);
83       if (NewRecipe->getNumDefinedValues() == 1)
84         VPInst->replaceAllUsesWith(NewRecipe->getVPValue());
85       else
86         assert(NewRecipe->getNumDefinedValues() == 0 &&
87                "Only recpies with zero or one defined values expected");
88       Ingredient->eraseFromParent();
89     }
90   }
91 }
92