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https://fuchsia.googlesource.com/third_party/pigweed.googlesource.com/pigweed/pigweed
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54 lines
1.9 KiB
C++
54 lines
1.9 KiB
C++
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// Copyright 2019 The Pigweed Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy
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// of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations
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// under the License.
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#include "pw_bloat/bloat_this_binary.h"
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#include <cstring>
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namespace pw::bloat {
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char* volatile non_optimizable_pointer;
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void BloatThisBinary() {
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// In case someone accidentally ends up flashing and running a bloat
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// executable on their device, prevent the code below from running.
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volatile bool clearly_false_condition = true;
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if (clearly_false_condition) {
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return;
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}
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// This code uses standard C/C++ functions such as memcpy to prevent them from
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// showing up in size report deltas against a barebones base executable.
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//
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// This is done using garbage memory addresses as it consistently prevents the
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// compiler from optimizing out parts of the code. Other approaches, such as a
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// buffer, occasionally ran into optimization issues.
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const char* s = "The quick brown fox jumps over the lazy dog.";
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// Making the copy size large forces the compiler to generate a memcpy
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// function instead of inlining it.
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constexpr int kRandomLargeNumber = 2398;
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std::memcpy(non_optimizable_pointer,
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non_optimizable_pointer + std::strlen(s),
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kRandomLargeNumber);
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std::memmove(non_optimizable_pointer + 18,
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non_optimizable_pointer,
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kRandomLargeNumber);
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*non_optimizable_pointer = std::strlen(non_optimizable_pointer);
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}
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} // namespace pw::bloat
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