llvm/lib/Transforms/Vectorize/VPlanVerifier.cpp

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