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

   1 //===- ReduceMetadata.cpp - Specialized Delta Pass ------------------------===//
   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 Metadata nodes.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "ReduceMetadata.h"
  15 #include "Delta.h"
  16 #include "llvm/ADT/Sequence.h"
  17 #include "llvm/ADT/SmallVector.h"
  18 #include "llvm/IR/InstIterator.h"
  19 #include "llvm/IR/IntrinsicInst.h"
  20
  21 using namespace llvm;
  22
  23 extern cl::OptionCategory LLVMReduceOptions;
  24
  25 static cl::opt<bool> AggressiveMetadataReduction(
  26     "aggressive-named-md-reduction",
  27     cl::desc("Reduce named metadata without taking its type into account"),
  28     cl::cat(LLVMReduceOptions));
  29
  30 static bool shouldKeepDebugIntrinsicMetadata(Instruction &I, MDNode &MD) {
  31   return isa<DILocation>(MD) && isa<DbgInfoIntrinsic>(I);
  32 }
  33
  34 static bool shouldKeepDebugNamedMetadata(NamedMDNode &MD) {
  35   return MD.getName() == "llvm.dbg.cu" && MD.getNumOperands() != 0;
  36 }
  37
  38 // Named metadata with simple list-like behavior, so that it's valid to remove
  39 // operands individually.
  40 static constexpr StringLiteral ListNamedMetadata[] = {
  41   "llvm.module.flags",
  42   "llvm.ident",
  43   "opencl.spir.version",
  44   "opencl.ocl.version",
  45   "opencl.used.extensions",
  46   "opencl.used.optional.core.features",
  47   "opencl.compiler.options"
  48 };
  49
  50 /// Remove unneeded arguments to named metadata.
  51 static void reduceNamedMetadataOperands(Oracle &O, ReducerWorkItem &WorkItem) {
  52   Module &M = WorkItem.getModule();
  53
  54   for (NamedMDNode &I : M.named_metadata()) {
  55     // If we don't want to reduce mindlessly, check if our node is part of
  56     // ListNamedMetadata before reducing it
  57     if (!AggressiveMetadataReduction &&
  58         !is_contained(ListNamedMetadata, I.getName()))
  59       continue;
  60
  61     bool MadeChange = false;
  62     SmallVector<MDNode *> KeptOperands;
  63     for (auto J : seq<unsigned>(0, I.getNumOperands())) {
  64       if (O.shouldKeep())
  65         KeptOperands.push_back(I.getOperand(J));
  66       else
  67         MadeChange = true;
  68     }
  69
  70     if (MadeChange) {
  71       I.clearOperands();
  72       for (MDNode *KeptOperand : KeptOperands)
  73         I.addOperand(KeptOperand);
  74     }
  75   }
  76 }
  77
  78 /// Removes all the Named and Unnamed Metadata Nodes, as well as any debug
  79 /// functions that aren't inside the desired Chunks.
  80 static void extractMetadataFromModule(Oracle &O, ReducerWorkItem &WorkItem) {
  81   Module &Program = WorkItem.getModule();
  82
  83   // Get out-of-chunk Named metadata nodes
  84   SmallVector<NamedMDNode *> NamedNodesToDelete;
  85   for (NamedMDNode &MD : Program.named_metadata())
  86     if (!shouldKeepDebugNamedMetadata(MD) && !O.shouldKeep())
  87       NamedNodesToDelete.push_back(&MD);
  88
  89   for (NamedMDNode *NN : NamedNodesToDelete) {
  90     for (auto I : seq<unsigned>(0, NN->getNumOperands()))
  91       NN->setOperand(I, nullptr);
  92     NN->eraseFromParent();
  93   }
  94
  95   // Delete out-of-chunk metadata attached to globals.
  96   for (GlobalVariable &GV : Program.globals()) {
  97     SmallVector<std::pair<unsigned, MDNode *>> MDs;
  98     GV.getAllMetadata(MDs);
  99     for (std::pair<unsigned, MDNode *> &MD : MDs)
 100       if (!O.shouldKeep())
 101         GV.setMetadata(MD.first, nullptr);
 102   }
 103
 104   for (Function &F : Program) {
 105     {
 106       SmallVector<std::pair<unsigned, MDNode *>> MDs;
 107       // Delete out-of-chunk metadata attached to functions.
 108       F.getAllMetadata(MDs);
 109       for (std::pair<unsigned, MDNode *> &MD : MDs)
 110         if (!O.shouldKeep())
 111           F.setMetadata(MD.first, nullptr);
 112     }
 113
 114     // Delete out-of-chunk metadata attached to instructions.
 115     for (Instruction &I : instructions(F)) {
 116       SmallVector<std::pair<unsigned, MDNode *>> MDs;
 117       I.getAllMetadata(MDs);
 118       for (std::pair<unsigned, MDNode *> &MD : MDs) {
 119         if (!shouldKeepDebugIntrinsicMetadata(I, *MD.second) && !O.shouldKeep())
 120           I.setMetadata(MD.first, nullptr);
 121       }
 122     }
 123   }
 124 }
 125
 126 void llvm::reduceMetadataDeltaPass(TestRunner &Test) {
 127   runDeltaPass(Test, extractMetadataFromModule, "Reducing Metadata");
 128 }
 129
 130 void llvm::reduceNamedMetadataDeltaPass(TestRunner &Test) {
 131   runDeltaPass(Test, reduceNamedMetadataOperands, "Reducing Named Metadata");
 132 }