StripUnkAttr/strip_unknown_attributes.cpp

/*
 * 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 "strip_unknown_attributes.h"

#include "llvm/IR/Function.h"

namespace slang {

bool stripUnknownAttributes(llvm::Function &F) {
  bool changed = false;
  for (llvm::Function::arg_iterator I = F.arg_begin(), E = F.arg_end();
       I != E; ++I) {
    llvm::Argument &A = *I;
    // Remove any readnone/readonly attributes from function parameters.
    if (A.onlyReadsMemory()) {
      llvm::AttrBuilder B;
      B.addAttribute(llvm::Attribute::ReadNone);
      B.addAttribute(llvm::Attribute::ReadOnly);
      llvm::AttributeSet ToStrip = llvm::AttributeSet::get(F.getContext(),
          A.getArgNo() + 1, B);
      A.removeAttr(ToStrip);
      changed = true;
    }
  }
  F.removeFnAttr(llvm::Attribute::ArgMemOnly);
  return changed;
}

}  // namespace slang