1 //===-- VPlanVerifier.cpp -------------------------------------------------===//
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 defines the class VPlanVerifier, which contains utility functions
11 /// to check the consistency and invariants of a VPlan.
12 ///
13 //===----------------------------------------------------------------------===//
14
15 #include "VPlanVerifier.h"
16 #include "llvm/ADT/DepthFirstIterator.h"
17 #include "llvm/Support/CommandLine.h"
18
19 #define DEBUG_TYPE "loop-vectorize"
20
21 using namespace llvm;
22
23 static cl::opt<bool> EnableHCFGVerifier("vplan-verify-hcfg", cl::init(false),
24 cl::Hidden,
25 cl::desc("Verify VPlan H-CFG."));
26
27 #ifndef NDEBUG
28 /// Utility function that checks whether \p VPBlockVec has duplicate
29 /// VPBlockBases.
hasDuplicates(const SmallVectorImpl<VPBlockBase * > & VPBlockVec)30 static bool hasDuplicates(const SmallVectorImpl<VPBlockBase *> &VPBlockVec) {
31 SmallDenseSet<const VPBlockBase *, 8> VPBlockSet;
32 for (const auto *Block : VPBlockVec) {
33 if (VPBlockSet.count(Block))
34 return true;
35 VPBlockSet.insert(Block);
36 }
37 return false;
38 }
39 #endif
40
41 /// Helper function that verifies the CFG invariants of the VPBlockBases within
42 /// \p Region. Checks in this function are generic for VPBlockBases. They are
43 /// not specific for VPBasicBlocks or VPRegionBlocks.
verifyBlocksInRegion(const VPRegionBlock * Region)44 static void verifyBlocksInRegion(const VPRegionBlock *Region) {
45 for (const VPBlockBase *VPB :
46 make_range(df_iterator<const VPBlockBase *>::begin(Region->getEntry()),
47 df_iterator<const VPBlockBase *>::end(Region->getExit()))) {
48 // Check block's parent.
49 assert(VPB->getParent() == Region && "VPBlockBase has wrong parent");
50
51 // Check block's condition bit.
52 if (VPB->getNumSuccessors() > 1)
53 assert(VPB->getCondBit() && "Missing condition bit!");
54 else
55 assert(!VPB->getCondBit() && "Unexpected condition bit!");
56
57 // Check block's successors.
58 const auto &Successors = VPB->getSuccessors();
59 // There must be only one instance of a successor in block's successor list.
60 // TODO: This won't work for switch statements.
61 assert(!hasDuplicates(Successors) &&
62 "Multiple instances of the same successor.");
63
64 for (const VPBlockBase *Succ : Successors) {
65 // There must be a bi-directional link between block and successor.
66 const auto &SuccPreds = Succ->getPredecessors();
67 assert(std::find(SuccPreds.begin(), SuccPreds.end(), VPB) !=
68 SuccPreds.end() &&
69 "Missing predecessor link.");
70 (void)SuccPreds;
71 }
72
73 // Check block's predecessors.
74 const auto &Predecessors = VPB->getPredecessors();
75 // There must be only one instance of a predecessor in block's predecessor
76 // list.
77 // TODO: This won't work for switch statements.
78 assert(!hasDuplicates(Predecessors) &&
79 "Multiple instances of the same predecessor.");
80
81 for (const VPBlockBase *Pred : Predecessors) {
82 // Block and predecessor must be inside the same region.
83 assert(Pred->getParent() == VPB->getParent() &&
84 "Predecessor is not in the same region.");
85
86 // There must be a bi-directional link between block and predecessor.
87 const auto &PredSuccs = Pred->getSuccessors();
88 assert(std::find(PredSuccs.begin(), PredSuccs.end(), VPB) !=
89 PredSuccs.end() &&
90 "Missing successor link.");
91 (void)PredSuccs;
92 }
93 }
94 }
95
96 /// Verify the CFG invariants of VPRegionBlock \p Region and its nested
97 /// VPBlockBases. Do not recurse inside nested VPRegionBlocks.
verifyRegion(const VPRegionBlock * Region)98 static void verifyRegion(const VPRegionBlock *Region) {
99 const VPBlockBase *Entry = Region->getEntry();
100 const VPBlockBase *Exit = Region->getExit();
101
102 // Entry and Exit shouldn't have any predecessor/successor, respectively.
103 assert(!Entry->getNumPredecessors() && "Region entry has predecessors.");
104 assert(!Exit->getNumSuccessors() && "Region exit has successors.");
105 (void)Entry;
106 (void)Exit;
107
108 verifyBlocksInRegion(Region);
109 }
110
111 /// Verify the CFG invariants of VPRegionBlock \p Region and its nested
112 /// VPBlockBases. Recurse inside nested VPRegionBlocks.
verifyRegionRec(const VPRegionBlock * Region)113 static void verifyRegionRec(const VPRegionBlock *Region) {
114 verifyRegion(Region);
115
116 // Recurse inside nested regions.
117 for (const VPBlockBase *VPB :
118 make_range(df_iterator<const VPBlockBase *>::begin(Region->getEntry()),
119 df_iterator<const VPBlockBase *>::end(Region->getExit()))) {
120 if (const auto *SubRegion = dyn_cast<VPRegionBlock>(VPB))
121 verifyRegionRec(SubRegion);
122 }
123 }
124
verifyHierarchicalCFG(const VPRegionBlock * TopRegion) const125 void VPlanVerifier::verifyHierarchicalCFG(
126 const VPRegionBlock *TopRegion) const {
127 if (!EnableHCFGVerifier)
128 return;
129
130 LLVM_DEBUG(dbgs() << "Verifying VPlan H-CFG.\n");
131 assert(!TopRegion->getParent() && "VPlan Top Region should have no parent.");
132 verifyRegionRec(TopRegion);
133 }
134