[llvm-bugs] [Bug 43650] New: [X86] Poor +/-1 integer sign extraction

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=43650

            Bug ID: 43650
           Summary: [X86] Poor +/-1 integer sign extraction
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: llvm-dev at redking.me.uk
                CC: craig.topper at gmail.com, llvm-bugs at lists.llvm.org,
                    llvm-dev at redking.me.uk, spatel+llvm at rotateright.com

https://godbolt.org/z/1ZT4eo

int sign_negone_one(int x)
{
    return x < 0 ? -1 : 1;
}

clang:

sign_negone_one:
  notl %edi
  shrl $31, %edi
  leal (%rdi,%rdi), %eax
  addl $-1, %eax
  retq

vs gcc:

sign_negone_one:
  movl %edi, %eax
  sarl $31, %eax
  orl $1, %eax
  ret

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