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

   1 //===- ReduceFunctions.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 functions (and any instruction that calls it) in the provided
  11 // Module.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "ReduceFunctions.h"
  16 #include "Delta.h"
  17 #include "Utils.h"
  18 #include "llvm/ADT/STLExtras.h"
  19 #include "llvm/Transforms/Utils/ModuleUtils.h"
  20 #include <iterator>
  21
  22 using namespace llvm;
  23
  24 /// Removes all the Defined Functions
  25 /// that aren't inside any of the desired Chunks.
  26 static void extractFunctionsFromModule(Oracle &O, ReducerWorkItem &WorkItem) {
  27   Module &Program = WorkItem.getModule();
  28
  29   // Record all out-of-chunk functions.
  30   SmallPtrSet<Constant *, 8> FuncsToRemove;
  31   for (Function &F : Program.functions()) {
  32     // Intrinsics don't have function bodies that are useful to
  33     // reduce. Additionally, intrinsics may have additional operand
  34     // constraints. But, do drop intrinsics that are not referenced.
  35     if ((!F.isIntrinsic() || F.use_empty()) && !hasAliasOrBlockAddressUse(F) &&
  36         !O.shouldKeep())
  37       FuncsToRemove.insert(&F);
  38   }
  39
  40   removeFromUsedLists(Program, [&FuncsToRemove](Constant *C) {
  41     return FuncsToRemove.count(C);
  42   });
  43
  44   // Then, drop body of each of them. We want to batch this and do nothing else
  45   // here so that minimal number of remaining exteranal uses will remain.
  46   for (Constant *F : FuncsToRemove)
  47     F->dropAllReferences();
  48
  49   // And finally, we can actually delete them.
  50   for (Constant *F : FuncsToRemove) {
  51     // Replace all *still* remaining uses with the default value.
  52     F->replaceAllUsesWith(getDefaultValue(F->getType()));
  53     // And finally, fully drop it.
  54     cast<Function>(F)->eraseFromParent();
  55   }
  56 }
  57
  58 void llvm::reduceFunctionsDeltaPass(TestRunner &Test) {
  59   runDeltaPass(Test, extractFunctionsFromModule, "Reducing Functions");
  60 }