// Copyright 2018 The Clspv Authors. All rights reserved.
//
// 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 <vector>

#include "llvm/IR/CallingConv.h"
#include "llvm/IR/Instructions.h"
#include "llvm/Pass.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/Cloning.h"

#include "clspv/Option.h"

#include "ArgKind.h"
#include "Passes.h"

using namespace llvm;

namespace {
class InlineFuncWithSingleCallSitePass : public ModulePass {
public:
  static char ID;
  InlineFuncWithSingleCallSitePass() : ModulePass(ID) {}

  bool runOnModule(Module &M) override;

private:
  bool InlineFunctions(Module &M);
};
} // namespace

namespace clspv {
ModulePass *createInlineFuncWithSingleCallSitePass() {
  return new InlineFuncWithSingleCallSitePass();
}
} // namespace clspv

char InlineFuncWithSingleCallSitePass::ID = 0;
INITIALIZE_PASS(InlineFuncWithSingleCallSitePass,
                "InlineFuncWithSingleCallSite",
                "Inline functions with a single call site pass", false, false)

bool InlineFuncWithSingleCallSitePass::runOnModule(Module &M) {
  if (!clspv::Option::InlineSingleCallSite())
    return false;

  bool Changed = false;
  for (bool local_changed = true; local_changed; Changed |= local_changed) {
    local_changed = InlineFunctions(M);
  }

  // Clean up dead functions. This done here to avoid ordering requirements on
  // inlining.
  std::vector<Function *> to_delete;
  for (auto &F : M) {
    if (F.isDeclaration() || F.getCallingConv() == CallingConv::SPIR_KERNEL)
      continue;

    if (F.user_empty())
      to_delete.push_back(&F);
  }
  for (auto func : to_delete) {
    func->eraseFromParent();
  }

  return Changed;
}

bool InlineFuncWithSingleCallSitePass::InlineFunctions(Module &M) {
  bool Changed = false;
  std::vector<CallInst *> to_inline;
  for (auto &F : M) {
    if (F.isDeclaration() || F.getCallingConv() == CallingConv::SPIR_KERNEL)
      continue;

    bool has_local_ptr_arg = false;
    for (auto &Arg : F.args()) {
      if (clspv::IsLocalPtr(Arg.getType()))
        has_local_ptr_arg = true;
    }

    // Only inline if the function has a local address space parameter.
    if (!has_local_ptr_arg)
      continue;

    if (F.getNumUses() == 1) {
      if (auto *call = dyn_cast<CallInst>(*F.user_begin()))
        to_inline.push_back(call);
    }
  }

  for (auto call : to_inline) {
    InlineFunctionInfo IFI;
    // Disable generation of lifetime intrinsic.
    Changed |= InlineFunction(*call, IFI, nullptr, false).isSuccess();
  }

  return Changed;
}