tools/llvm-reduce/deltas/ReduceArguments.cpp

   1 //===- ReduceArguments.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 a function which calls the Generic Delta pass in order
  10 // to reduce uninteresting Arguments from defined functions.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "ReduceArguments.h"
  15 #include "Delta.h"
  16 #include "llvm/ADT/SmallVector.h"
  17 #include <set>
  18 #include <vector>
  19
  20 using namespace llvm;
  21
  22 /// Goes over OldF calls and replaces them with a call to NewF
  23 static void replaceFunctionCalls(Function &OldF, Function &NewF,
  24                                  const std::set<int> &ArgIndexesToKeep) {
  25   const auto &Users = OldF.users();
  26   for (auto I = Users.begin(), E = Users.end(); I != E; )
  27     if (auto *CI = dyn_cast<CallInst>(*I++)) {
  28       SmallVector<Value *, 8> Args;
  29       for (auto ArgI = CI->arg_begin(), E = CI->arg_end(); ArgI != E; ++ArgI)
  30         if (ArgIndexesToKeep.count(ArgI - CI->arg_begin()))
  31           Args.push_back(*ArgI);
  32
  33       CallInst *NewCI = CallInst::Create(&NewF, Args);
  34       NewCI->setCallingConv(NewF.getCallingConv());
  35       if (!CI->use_empty())
  36         CI->replaceAllUsesWith(NewCI);
  37       ReplaceInstWithInst(CI, NewCI);
  38     }
  39 }
  40
  41 /// Removes out-of-chunk arguments from functions, and modifies their calls
  42 /// accordingly. It also removes allocations of out-of-chunk arguments.
  43 static void extractArgumentsFromModule(std::vector<Chunk> ChunksToKeep,
  44                                        Module *Program) {
  45   int I = 0, ArgCount = 0;
  46   std::set<Argument *> ArgsToKeep;
  47   std::vector<Function *> Funcs;
  48   // Get inside-chunk arguments, as well as their parent function
  49   for (auto &F : *Program)
  50     if (!F.isDeclaration()) {
  51       Funcs.push_back(&F);
  52       for (auto &A : F.args())
  53         if (I < (int)ChunksToKeep.size()) {
  54           if (ChunksToKeep[I].contains(++ArgCount))
  55             ArgsToKeep.insert(&A);
  56           if (ChunksToKeep[I].end == ArgCount)
  57             ++I;
  58         }
  59     }
  60
  61   for (auto *F : Funcs) {
  62     ValueToValueMapTy VMap;
  63     std::vector<Instruction *> InstToDelete;
  64     for (auto &A : F->args())
  65       if (!ArgsToKeep.count(&A)) {
  66         // By adding undesired arguments to the VMap, CloneFunction will remove
  67         // them from the resulting Function
  68         VMap[&A] = UndefValue::get(A.getType());
  69         for (auto *U : A.users())
  70           if (auto *I = dyn_cast<Instruction>(*&U))
  71             InstToDelete.push_back(I);
  72       }
  73     // Delete any instruction that uses the argument
  74     for (auto *I : InstToDelete) {
  75       I->replaceAllUsesWith(UndefValue::get(I->getType()));
  76       I->eraseFromParent();
  77     }
  78
  79     // No arguments to reduce
  80     if (VMap.empty())
  81       continue;
  82
  83     std::set<int> ArgIndexesToKeep;
  84     int ArgI = 0;
  85     for (auto &Arg : F->args())
  86       if (ArgsToKeep.count(&Arg))
  87         ArgIndexesToKeep.insert(++ArgI);
  88
  89     auto *ClonedFunc = CloneFunction(F, VMap);
  90     // In order to preserve function order, we move Clone after old Function
  91     ClonedFunc->removeFromParent();
  92     Program->getFunctionList().insertAfter(F->getIterator(), ClonedFunc);
  93
  94     replaceFunctionCalls(*F, *ClonedFunc, ArgIndexesToKeep);
  95     // Rename Cloned Function to Old's name
  96     std::string FName = F->getName();
  97     F->eraseFromParent();
  98     ClonedFunc->setName(FName);
  99   }
 100 }
 101
 102 /// Counts the amount of arguments in non-declaration functions and prints their
 103 /// respective name, index, and parent function name
 104 static int countArguments(Module *Program) {
 105   // TODO: Silence index with --quiet flag
 106   outs() << "----------------------------\n";
 107   outs() << "Param Index Reference:\n";
 108   int ArgsCount = 0;
 109   for (auto &F : *Program)
 110     if (!F.isDeclaration() && F.arg_size()) {
 111       outs() << "  " << F.getName() << "\n";
 112       for (auto &A : F.args())
 113         outs() << "\t" << ++ArgsCount << ": " << A.getName() << "\n";
 114
 115       outs() << "----------------------------\n";
 116     }
 117
 118   return ArgsCount;
 119 }
 120
 121 void llvm::reduceArgumentsDeltaPass(TestRunner &Test) {
 122   outs() << "*** Reducing Arguments...\n";
 123   int ArgCount = countArguments(Test.getProgram());
 124   runDeltaPass(Test, ArgCount, extractArgumentsFromModule);
 125 }