[Bug tree-optimization/67328] range test rather than single bit test for code testing enum values

[amodra at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67328

Alan Modra <amodra at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW

--- Comment #3 from Alan Modra <amodra at gmail dot com> ---
Maybe adding #if ALT only confused the issue.  For -UALT -O1 on x86_64 I get

test_pic:
        testb   $1, (%rdi)
        je      .L1
        addl    $1, result(%rip)
.L1:
        rep ret

test_exe:
        movzbl  (%rdi), %eax
        andl    $3, %eax
        cmpb    $1, %al
        ja      .L3
        addl    $1, result(%rip)
.L3:
        rep ret

For test_exe I would like to see the following equivalent and better optimised
code.

test_exe:
        testb   $2, (%rdi)
        jne     .L3
        addl    $1, result(%rip)
.L3:
        rep ret

The optimisation to a bit test for test_pic happens in reassoc1, or at least
that's where the process starts.