text: // Copyright 2019 The Pigweed Authors
  //
  // 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
  //
  //     https://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 "pw_bloat/bloat_this_binary.h"
  
  #include <cstring>
  
  #include "pw_assert/assert.h"
  #include "pw_assert/check.h"
  #include "pw_log/log.h"
  
  namespace pw::bloat {
  
  char* volatile non_optimizable_pointer;
  
  void BloatThisBinary() {
    [[maybe_unused]] volatile unsigned counter = 0;
  
    // In case someone accidentally ends up flashing and running a bloat
    // executable on their device, loop forever instead of running this code.
    volatile bool clearly_false_condition = true;
    while (clearly_false_condition) {
      counter += 1;
    }
  
    // This code uses standard C/C++ functions such as memcpy to prevent them from
    // showing up in size report deltas against a barebones base executable.
    //
    // This is done using garbage memory addresses as it consistently prevents the
    // compiler from optimizing out parts of the code. Other approaches, such as a
    // buffer, occasionally ran into optimization issues.
    const char* s = "The quick brown fox jumps over the lazy dog.";
  
    // Making the copy size large forces the compiler to generate a memcpy
    // function instead of inlining it.
    constexpr int kRandomLargeNumber = 2398;
    std::memcpy(non_optimizable_pointer,
                non_optimizable_pointer + std::strlen(s),
                kRandomLargeNumber);
  
    std::memmove(non_optimizable_pointer + 18,
                 non_optimizable_pointer,
                 kRandomLargeNumber);
  
    *non_optimizable_pointer = std::strlen(non_optimizable_pointer);
  
    // This code ensures users do not have to pay for the base cost of using
    // asserts and logging.
    PW_ASSERT(*non_optimizable_pointer);
    PW_DASSERT(*non_optimizable_pointer);
    PW_CHECK_INT_GE(*non_optimizable_pointer, 0, "Ensure this logic stays");
    PW_DCHECK_INT_GE(*non_optimizable_pointer, 0, "Ensure this logic stays");
    PW_LOG_INFO("We care about optimizing: %d", *non_optimizable_pointer);
  }
  
  }  // namespace pw::bloat
  