Re: [Valgrind-users] uninitialized value error with packed structure

[Tom H. <to...@co...>]

Julian Seward wrote:

>> Thanks. I don't think it actually makes any difference though. I can
>> reproduce what you're seeing on F10 x86 with the original program.
> 
> Could you pls send the objdump -d of the insn it's complaining about
> + the few preceding ones, so as to show how the flags get set?

Here's the dump of main - the jp at 0x80484ff is the one that valgrind 
is complaining about:

080484c4 <main>:
  80484c4:	8d 4c 24 04          	lea    0x4(%esp),%ecx
  80484c8:	83 e4 f0             	and    $0xfffffff0,%esp
  80484cb:	ff 71 fc             	pushl  -0x4(%ecx)
  80484ce:	55                   	push   %ebp
  80484cf:	89 e5                	mov    %esp,%ebp
  80484d1:	51                   	push   %ecx
  80484d2:	83 ec 24             	sub    $0x24,%esp
  80484d5:	c7 04 24 02 00 00 00 	movl   $0x2,(%esp)
  80484dc:	e8 f7 fe ff ff       	call   80483d8 <_Znwj@plt>
  80484e1:	0f b6 10             	movzbl (%eax),%edx
  80484e4:	83 e2 c0             	and    $0xffffffc0,%edx
  80484e7:	88 10                	mov    %dl,(%eax)
  80484e9:	89 45 ec             	mov    %eax,-0x14(%ebp)
  80484ec:	d9 ee                	fldz
  80484ee:	dd 5d f0             	fstpl  -0x10(%ebp)
  80484f1:	dd 45 f0             	fldl   -0x10(%ebp)
  80484f4:	d9 ee                	fldz
  80484f6:	d9 c9                	fxch   %st(1)
  80484f8:	da e9                	fucompp
  80484fa:	df e0                	fnstsw %ax
  80484fc:	9e                   	sahf
  80484fd:	75 0e                	jne    804850d <main+0x49>
  80484ff:	7a 0c                	jp     804850d <main+0x49>
  8048501:	c7 04 24 e4 85 04 08 	movl   $0x80485e4,(%esp)
  8048508:	e8 db fe ff ff       	call   80483e8 <puts@plt>
  804850d:	b8 00 00 00 00       	mov    $0x0,%eax
  8048512:	83 c4 24             	add    $0x24,%esp
  8048515:	59                   	pop    %ecx
  8048516:	5d                   	pop    %ebp
  8048517:	8d 61 fc             	lea    -0x4(%ecx),%esp
  804851a:	c3                   	ret

Tom

-- 
Tom Hughes (to...@co...)
http://www.compton.nu/