| // 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> |
| |
| namespace pw::bloat { |
| |
| char* volatile non_optimizable_pointer; |
| |
| void BloatThisBinary() { |
| 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); |
| } |
| |
| } // namespace pw::bloat |