[Bug target/36713] [4.4 regression] r137252 breaks -O2 optimization on x86_64-unknown-linux-gnu

["rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #16 from rguenther at suse dot de  2008-07-03 19:26 -------
Subject: Re:  [4.4 regression] r137252 breaks -O2 optimization
 on x86_64-unknown-linux-gnu

On Thu, 3 Jul 2008, dfranke at gcc dot gnu dot org wrote:

> ------- Comment #15 from dfranke at gcc dot gnu dot org  2008-07-03 18:59 -------
>> Your challenge is now to produce a testcase from your source ;)
>
> I do have a testcase that shows said flags. The difference in assembler between
> -foptimize-sibling-calls and -fno-optimize-sibling-calls is:
>
> --- without.s 2008-07-03 20:51:59.000000000 +0200
> +++ with.s    2008-07-03 20:52:26.000000000 +0200
> @@ -64,10 +64,9 @@
>        movq    %rsp, %rdi
>        call    dummy_atom_model_inertia_tensor_
>        movq    %rsp, %rdi
> -       call    inertia_tensor_to_rg_
>        addq    $80, %rsp
>        popq    %rbx
> -       ret
> +       jmp     inertia_tensor_to_rg_
> .LFE2:
>        .size   dummy_atom_model_radius_of_gyration_,
> .-dummy_atom_model_radius_of_gyration_
>        .section        .eh_frame,"a",@progbits
>
> Is this correct? Running the code compiled with -foptimize-sibling-calls seems
> to yield the correct result. Not sure if I need to investigate further.

Well, the circumstances where the miscompilation occurs may be tricky.
So you say you have a testcase but that doesn't show wrong behavior?
That's unfortunate ... :/

Richard.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36713