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