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[optimization missed] Why do x86 gcc need extension here?

Simple test:

struct U {
  unsigned s: 1;

struct V {
  unsigned short o: 7;
  unsigned short u: 1;

extern struct U t[];
extern struct V d[];

foo ()
    struct V descr = d[0];
    unsigned osize = descr.o;
    if ( descr.u )
        struct U udata = t[osize];
        if (udata.s) osize++;
    return osize;

Compiled with specified gcc:

>gcc -v
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-5.2.0/configure
--prefix=/tools/local/gcc-5.2.0 --program-suffix=-5.2.0
Thread model: posix
gcc version 5.2.0 (GCC)


with options:  -02 -S


Yields assembler:


        movzbl  d(%rip), %eax
        andl    $127, %eax
        cmpb    $0, d(%rip)
        movzbl  %al, %eax // <----- why this is here?
        jns     .L2
        movl    %eax, %edx
        movl    t(,%rdx,4), %edx
        andl    $1, %edx
        cmpb    $1, %dl
        sbbl    $-1, %eax
        rep ret

I can not understand why second movzbl is here? andl already bitwise
and register eax with 127, why do someone need to zero-extend it one
more time?

May be some optimization missed here and it makes sense to file a
ticket in bugzilla? Or maybe I do not understand something?

Problem go away if I change unsigned short to unsigned int in bitfield
type inside structure V.

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