text: /*
   * Copyright 2017, The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #include "RemoveNonkernelsPass.h"
  
  #include "llvm/ADT/Triple.h"
  #include "llvm/IR/Constants.h"
  #include "llvm/IR/Module.h"
  #include "llvm/Pass.h"
  #include "llvm/Support/Debug.h"
  #include "llvm/Support/raw_ostream.h"
  
  #include "Context.h"
  
  #define DEBUG_TYPE "rs2spirv-remove"
  
  using namespace llvm;
  
  namespace rs2spirv {
  
  namespace {
  
  void HandleTargetTriple(llvm::Module &M) {
    Triple TT(M.getTargetTriple());
    auto Arch = TT.getArch();
  
    StringRef NewTriple;
    switch (Arch) {
    default:
      llvm_unreachable("Unrecognized architecture");
      break;
    case Triple::arm:
      NewTriple = "spir-unknown-unknown";
      break;
    case Triple::aarch64:
      NewTriple = "spir64-unknown-unknown";
      break;
    case Triple::spir:
    case Triple::spir64:
      DEBUG(dbgs() << "!!! Already a spir triple !!!\n");
    }
  
    DEBUG(dbgs() << "New triple:\t" << NewTriple << "\n");
    M.setTargetTriple(NewTriple);
  }
  
  class RemoveNonkernelsPass : public ModulePass {
  public:
    static char ID;
    explicit RemoveNonkernelsPass() : ModulePass(ID) {}
  
    const char *getPassName() const override { return "RemoveNonkernelsPass"; }
  
    bool runOnModule(Module &M) override {
      DEBUG(dbgs() << "RemoveNonkernelsPass\n");
      DEBUG(M.dump());
  
      HandleTargetTriple(M);
  
      rs2spirv::Context &Ctxt = rs2spirv::Context::getInstance();
  
      if (Ctxt.getNumForEachKernel() == 0) {
        DEBUG(dbgs() << "RemoveNonkernelsPass detected no kernel\n");
        // Returns false, since no modification is made to the Module.
        return false;
      }
  
      std::vector<Function *> Functions;
      for (auto &F : M.functions()) {
        Functions.push_back(&F);
      }
  
      for (auto &F : Functions) {
        if (F->isDeclaration())
          continue;
  
        if (Ctxt.isForEachKernel(F->getName())) {
          continue; // Skip kernels.
        }
  
        F->replaceAllUsesWith(UndefValue::get((Type *)F->getType()));
        F->eraseFromParent();
  
        DEBUG(dbgs() << "Removed:\t" << F->getName() << '\n');
      }
  
      DEBUG(M.dump());
      DEBUG(dbgs() << "Done removal\n");
  
      // Returns true, because the pass modifies the Module.
      return true;
    }
  };
  
  } // namespace
  
  char RemoveNonkernelsPass::ID = 0;
  
  ModulePass *createRemoveNonkernelsPass() {
    return new RemoveNonkernelsPass();
  }
  
  } // namespace rs2spirv
  