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// 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
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