[llvm-bugs] [Bug 47191] New: Missing bswap

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=47191

            Bug ID: 47191
           Summary: Missing bswap
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Common Code Generator Code
          Assignee: unassignedbugs at nondot.org
          Reporter: david.bolvansky at gmail.com
                CC: llvm-bugs at lists.llvm.org

64-bit cases:
#include <stdint.h>
#include <cstddef>

uint64_t problem1(uint64_t input) {
  return (((input & 0xFF00000000000000ULL) >> 56) +
          ((input & 0x00FF000000000000ULL) >> 40) +
          ((input & 0x0000FF0000000000ULL) >> 24) +
          ((input & 0x000000FF00000000ULL) >> 8) +
          ((input & 0x00000000000000FFULL) << 56) +
          ((input & 0x000000000000FF00ULL) << 40) +
          ((input & 0x0000000000FF0000ULL) << 24) +
          ((input & 0x00000000FF000000ULL) << 8));
}

uint64_t problem2(uint64_t input) {
  return (((input >> 56) & 0x00000000000000FFULL) ^
          ((input >> 40) & 0x000000000000FF00ULL) ^
          ((input >> 24) & 0x0000000000FF0000ULL) ^
          ((input >> 8) & 0x00000000FF000000ULL) ^
          ((input << 56) & 0xFF00000000000000ULL) ^
          ((input << 40) & 0x00FF000000000000ULL) ^
          ((input << 24) & 0x0000FF0000000000ULL) ^
          ((input << 8) & 0x000000FF00000000ULL));
}

uint64_t problem3(uint64_t input) {
  return (((input & 0xFF00000000000000ULL) >> 56) ^
          ((input & 0x00FF000000000000ULL) >> 40) ^
          ((input & 0x0000FF0000000000ULL) >> 24) ^
          ((input & 0x000000FF00000000ULL) >> 8) ^
          ((input & 0x00000000000000FFULL) << 56) ^
          ((input & 0x000000000000FF00ULL) << 40) ^
          ((input & 0x0000000000FF0000ULL) << 24) ^
          ((input & 0x00000000FF000000ULL) << 8));
}

uint64_t problem4(uint64_t input) {
  return (((input >> 56) & 0x00000000000000FFULL) +
          ((input << 56) & 0xFF00000000000000ULL) +
          ((input >> 40) & 0x000000000000FF00ULL) +
          ((input << 40) & 0x00FF000000000000ULL) +
          ((input >> 24) & 0x0000000000FF0000ULL) +
          ((input << 24) & 0x0000FF0000000000ULL) +
          ((input >> 8) & 0x00000000FF000000ULL) +
          ((input << 8) & 0x000000FF00000000ULL));
}

https://godbolt.org/z/vzznPz

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