qemu/host-utils: Use __builtin_bitreverseN
Clang has added some builtins for these operations; use them if available. Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
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@ -272,6 +272,9 @@ static inline int ctpop64(uint64_t val)
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*/
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static inline uint8_t revbit8(uint8_t x)
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{
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#if __has_builtin(__builtin_bitreverse8)
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return __builtin_bitreverse8(x);
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#else
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/* Assign the correct nibble position. */
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x = ((x & 0xf0) >> 4)
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| ((x & 0x0f) << 4);
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@ -281,6 +284,7 @@ static inline uint8_t revbit8(uint8_t x)
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| ((x & 0x22) << 1)
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| ((x & 0x11) << 3);
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return x;
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#endif
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}
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/**
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@ -289,6 +293,9 @@ static inline uint8_t revbit8(uint8_t x)
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*/
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static inline uint16_t revbit16(uint16_t x)
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{
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#if __has_builtin(__builtin_bitreverse16)
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return __builtin_bitreverse16(x);
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#else
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/* Assign the correct byte position. */
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x = bswap16(x);
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/* Assign the correct nibble position. */
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@ -300,6 +307,7 @@ static inline uint16_t revbit16(uint16_t x)
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| ((x & 0x2222) << 1)
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| ((x & 0x1111) << 3);
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return x;
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#endif
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}
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/**
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@ -308,6 +316,9 @@ static inline uint16_t revbit16(uint16_t x)
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*/
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static inline uint32_t revbit32(uint32_t x)
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{
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#if __has_builtin(__builtin_bitreverse32)
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return __builtin_bitreverse32(x);
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#else
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/* Assign the correct byte position. */
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x = bswap32(x);
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/* Assign the correct nibble position. */
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@ -319,6 +330,7 @@ static inline uint32_t revbit32(uint32_t x)
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| ((x & 0x22222222u) << 1)
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| ((x & 0x11111111u) << 3);
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return x;
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#endif
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}
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/**
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@ -327,6 +339,9 @@ static inline uint32_t revbit32(uint32_t x)
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*/
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static inline uint64_t revbit64(uint64_t x)
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{
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#if __has_builtin(__builtin_bitreverse64)
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return __builtin_bitreverse64(x);
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#else
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/* Assign the correct byte position. */
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x = bswap64(x);
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/* Assign the correct nibble position. */
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@ -338,6 +353,7 @@ static inline uint64_t revbit64(uint64_t x)
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| ((x & 0x2222222222222222ull) << 1)
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| ((x & 0x1111111111111111ull) << 3);
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return x;
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#endif
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}
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/* Host type specific sizes of these routines. */
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