llvm/tools/llvm-reduce/deltas/ReduceDIMetadata.cpp

   1 //===- ReduceDIMetadata.cpp - Specialized Delta pass for DebugInfo --------===//
   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 // This file implements two functions used by the Generic Delta Debugging
  10 // Algorithm, which are used to reduce DebugInfo metadata nodes.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "ReduceDIMetadata.h"
  15 #include "Delta.h"
  16 #include "llvm/ADT/Sequence.h"
  17 #include "llvm/ADT/SetVector.h"
  18 #include "llvm/ADT/SmallSet.h"
  19 #include "llvm/ADT/SmallVector.h"
  20 #include "llvm/IR/DebugInfoMetadata.h"
  21 #include "llvm/IR/InstIterator.h"
  22 #include <set>
  23 #include <stack>
  24 #include <tuple>
  25 #include <vector>
  26
  27 using namespace llvm;
  28
  29 using MDNodeList = SmallVector<MDNode *>;
  30
  31 void identifyUninterestingMDNodes(Oracle &O, MDNodeList &MDs) {
  32   SetVector<std::tuple<MDNode *, size_t, MDNode *>> Tuples;
  33   std::vector<MDNode *> ToLook;
  34   SetVector<MDNode *> Visited;
  35
  36   // Start by looking at the attachments we collected
  37   for (const auto &NMD : MDs)
  38     if (NMD)
  39       ToLook.push_back(NMD);
  40
  41   while (!ToLook.empty()) {
  42     MDNode *MD = ToLook.back();
  43     ToLook.pop_back();
  44
  45     if (Visited.count(MD))
  46       continue;
  47
  48     // Determine if the current MDNode is DebugInfo
  49     if (DINode *DIM = dyn_cast_or_null<DINode>(MD)) {
  50       // Scan operands and record attached tuples
  51       for (size_t I = 0; I < DIM->getNumOperands(); ++I)
  52         if (MDTuple *MDT = dyn_cast_or_null<MDTuple>(DIM->getOperand(I)))
  53           if (!Visited.count(MDT) && MDT->getNumOperands())
  54             Tuples.insert({DIM, I, MDT});
  55     }
  56
  57     // Add all of the operands of the current node to the loop's todo list.
  58     for (Metadata *Op : MD->operands())
  59       if (MDNode *OMD = dyn_cast_or_null<MDNode>(Op))
  60         ToLook.push_back(OMD);
  61
  62     Visited.insert(MD);
  63   }
  64
  65   for (auto &T : Tuples) {
  66     auto [DbgNode, OpIdx, Tup] = T;
  67     // Remove the operands of the tuple that are not in the desired chunks.
  68     SmallVector<Metadata *, 16> TN;
  69     for (size_t I = 0; I < Tup->getNumOperands(); ++I) {
  70       // Ignore any operands that are not DebugInfo metadata nodes.
  71       if (isa_and_nonnull<DINode>(Tup->getOperand(I)))
  72         // Don't add uninteresting operands to the tuple.
  73         if (!O.shouldKeep())
  74           continue;
  75
  76       TN.push_back(Tup->getOperand(I));
  77     }
  78     if (TN.size() != Tup->getNumOperands())
  79       DbgNode->replaceOperandWith(OpIdx, DbgNode->get(DbgNode->getContext(), TN));
  80   }
  81 }
  82
  83 static void extractDIMetadataFromModule(Oracle &O, ReducerWorkItem &WorkItem) {
  84   Module &Program = WorkItem.getModule();
  85
  86   MDNodeList MDs;
  87   // Collect all !dbg metadata attachments.
  88   for (const auto &DC : Program.debug_compile_units())
  89     if (DC)
  90       MDs.push_back(DC);
  91   for (GlobalVariable &GV : Program.globals())
  92     GV.getMetadata(llvm::LLVMContext::MD_dbg, MDs);
  93   for (Function &F : Program.functions()) {
  94     F.getMetadata(llvm::LLVMContext::MD_dbg, MDs);
  95     for (Instruction &I : instructions(F))
  96       if (auto *DI = I.getMetadata(llvm::LLVMContext::MD_dbg))
  97         MDs.push_back(DI);
  98   }
  99   identifyUninterestingMDNodes(O, MDs);
 100 }
 101
 102 void llvm::reduceDIMetadataDeltaPass(TestRunner &Test) {
 103   runDeltaPass(Test, extractDIMetadataFromModule, "Reducing DIMetadata");
 104 }