[Bug target/31943] New: very missed optimization.

[pluto at agmk dot net]

please look at the 32-bit asm. dump:

_Z3msby:
        pushl   %ebx
        movl    12(%esp), %edx
        movl    8(%esp), %eax
        popl    %ebx
        movl    %edx, %eax
        xorl    %edx, %edx
        shrl    $24, %eax
        movzbl  %al,%ecx
        movzbl  %cl, %eax
        ret

wow! this could be done within two intructions:

        movzbl  11(%esp), %eax
        ret

the 64-bits variant looks fine:

_Z3msby:
        movq    %rdi, %rax
        shrq    $56, %rax
        ret


-- 
           Summary: very missed optimization.
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pluto at agmk dot net
GCC target triplet: i386-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31943