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     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