[PATCH] D29088: Do not create ctlz/cttz(X, false) when the target do not support zero defined ctlz/cttz.

[Amaury SECHET via Phabricator via llvm-commits]

deadalnix added a comment.

And the codegen:

  _D2gc1d4util6decodeFMKAxhZm:
        movq    8(%rdi), %rax
        movb    (%rax), %al
        cmpb    $-1, %al
        je      .LBB2_5
        je      .LBB2_2
        notb    %al
        movzbl  %al, %eax
        bsrl    %eax, %eax
        xorl    $7, %eax
        movzbl  %al, %eax
        retq
  .LBB2_5:
        movl    $23, %eax
        retq
  .LBB2_2:
        movb    $8, %al
        movzbl  %al, %eax
        retq

Note the double branch.


https://reviews.llvm.org/D29088