Re: Ping: Re: [patch middle-end]: Fix PR/48814 - [4.4/4.5/4.6/4.7 Regression] Incorrect scalar increment result

[Richard Guenther <richard dot guenther at gmail dot com>]

On Thu, Feb 9, 2012 at 11:29 AM, Richard Guenther
<richard.guenther@gmail.com> wrote:
> On Wed, Feb 8, 2012 at 10:25 PM, Kai Tietz <ktietz70@googlemail.com> wrote:
>> 2012/1/11 Richard Guenther <richard.guenther@gmail.com>:
>>>
>>> count despite being declared volatile and only loaded once in the source
>>> is loaded twice in gimple. ?If it were a HW register which destroys the
>>> device after the 2nd load without an intervening store you'd wrecked
>>> the device ;)
>>>
>>> Richard.
>>
>> Thanks for explaination. ?I tried to flip order for lhs/rhs in
>> gimplify_modify_expr & co. ?Issue here is that for some cases we are
>> relying here on lhs for gimplifying rhs (is_gimple_reg_rhs_or_call vs
>> is_gimple_mem_rhs_or_call) and this doesn't work for cases in C++
>> like:
>>
>> typedef const unsigned char _Jv_Utf8Const;
>> typedef __SIZE_TYPE__ uaddr;
>>
>> void maybe_adjust_signature (_Jv_Utf8Const *&s, uaddr &special)
>> {
>> ?union {
>> ? ?_Jv_Utf8Const *signature;
>> ? ?uaddr signature_bits;
>> ?};
>> ?signature = s;
>> ?special = signature_bits & 1;
>> ?signature_bits -= special;
>> ?s = signature;
>> }
>>
>> So I modified gimplify_self_mod_expr for post-inc/dec so that we use
>> following sequence
>> and add it to pre_p for it:
>>
>> tmp = lhs;
>> lvalue = tmp (+/-) rhs
>> *expr_p = tmp;
>
> As I explained this is the wrong place to fix the PR. ?The issue is not
> about self-modifying expressions but about evaluating call argument
> side-effects before side-effects of the lhs.

I am testing the attached instead.

Richard.

2012-02-09  Richard Guenther  <rguenther@suse.de>

        PR middle-end/48814
        * gimplify.c (gimplify_modify_expr): Perform side-effects of
        the RHS before those of the LHS.

2012-02-08  Kai Tietz  <ktietz@redhat.com>

        * gcc.c-torture/execute/pr48814-1.c: New test.
        * gcc.c-torture/execute/pr48814-2.c: New test.
        * gcc.dg/tree-ssa/assign-1.c: New test.
        * gcc.dg/tree-ssa/assign-2.c: New test.

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