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Merge pull request #8560 from liamwhite/bitfield-may-alias 

common: fix bitfield aliasing on GCC/Clang
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bunnei 2022-07-15 22:16:52 -07:00 committed by GitHub
parent d2c0b45bca a1c1ad096d
commit 93a4ca11fa
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1 changed files with 9 additions and 0 deletions
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9
src/common/bit_field.h
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@ -146,7 +146,16 @@ public:
} }
constexpr void Assign(const T& value) { constexpr void Assign(const T& value) {
#ifdef _MSC_VER
storage = static_cast<StorageType>((storage & ~mask) | FormatValue(value)); storage = static_cast<StorageType>((storage & ~mask) | FormatValue(value));
#else
// Explicitly reload with memcpy to avoid compiler aliasing quirks
// regarding optimization: GCC/Clang clobber chained stores to
// different bitfields in the same struct with the last value.
StorageTypeWithEndian storage_;
std::memcpy(&storage_, &storage, sizeof(storage_));
storage = static_cast<StorageType>((storage_ & ~mask) | FormatValue(value));
#endif
} }
[[nodiscard]] constexpr T Value() const { [[nodiscard]] constexpr T Value() const {