[llvm-bugs] [Bug 47193] New: Missed btc opportunities

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=47193

            Bug ID: 47193
           Summary: Missed btc opportunities
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: david.bolvansky at gmail.com
                CC: craig.topper at gmail.com, llvm-bugs at lists.llvm.org,
                    llvm-dev at redking.me.uk, spatel+llvm at rotateright.com

uint16_t toggle16(uint16_t num, uint16_t bit) {
  num ^= 1ULL << bit;
  return num;
}


uint32_t toggle32(uint32_t num, uint32_t bit) {
  num ^= 1ULL << bit;
  return num;
}

uint64_t toggle64(uint64_t num, uint32_t bit) {
  num ^= 1ULL << bit;
  return num;
}

uint64_t case1(unsigned long num, uint64_t bit)
{
  num ^= 1U << bit;
  return num;
}


uint64_t case2(unsigned long num, uint64_t bit)
{
  num ^= 1UL << bit;
  return num;
}


Clang:

toggle16:                               # @toggle16
        mov     ecx, esi
        mov     eax, 1
        shl     rax, cl
        xor     eax, edi
        ret
toggle32:                               # @toggle32
        mov     ecx, esi
        mov     eax, 1
        shl     rax, cl
        xor     eax, edi
        ret
toggle64:                               # @toggle64
        mov     rax, rdi
        btc     rax, rsi
        ret

case1(unsigned long, unsigned long):                             #
@case1(unsigned long, unsigned long)
        mov     rcx, rsi
        mov     eax, 1
        shl     eax, cl
        xor     rax, rdi
        ret
case2(unsigned long, unsigned long):                             #
@case2(unsigned long, unsigned long)
        mov     rax, rdi
        btc     rax, rsi
        ret


MSVC can catch all cases and produce btc.
https://gcc.godbolt.org/z/oE9qdz

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