Hi Jeff, Steven,
I have filed a bug at http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50663
Could somebody confirm it?
I am studying this piece of codes and have spent some time on it,
I'm working on a patch and hoping could help on this issue,
Please help me review it later. Thanks.
--
Best Regar
Hi,
> Though conditional const information "r684 <- 0" is collected by
> find_implicit_sets, the conditional information is recorded as local
> information of bb 97, and it is not recorded in avout of bb 96, so not
> in avin of bb 97 either.
To have the set in avout of bb 96 would be wrong becaus
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On 09/29/11 22:43, Amker.Cheng wrote:
>>>
>>> I believe, the optimization you may be referring to is value
>>> range propagation which does predication of values based on
>>> predicates of conditions. GCC definitely applies VRP at the
>>> tree stage,
>>
>> I believe, the optimization you may be referring to is value range
>> propagation which does predication of values based on predicates of
>> conditions. GCC definitely applies VRP at the tree stage, I am not
>> sure if there is an RTL pass to do the same.
> There are also RTL optimizers which
>
> Nobody mentioned this so I might be way off but cc doesn't get (minus
> (reg r684) (const_int 0)). It gets the `condition codes` modification as
> a consequence of the subtraction.
>
Hi Paulo,
According to section "comparison operations" in internal:
"The comparison operators may be used to co
"Amker.Cheng" writes:
>
> Thanks for replying.
> Sorry if I misunderstood anything below, and please correct me.
>
> insn 882 : cc <- compare (r684, 0)
> jump_insn 883 : if (cc != 0) goto insn 46
> insn 49: r291 <- r684
> ..
> insn 46
>
> cc contains the result of subtract
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On 09/29/11 09:48, Rahul Kharche wrote:
>> On 09/29/11 17:36, Jeff Law wrote:
>>> On 09/29/11 09:26, Bernd Schmidt wrote:
ISTR cse.c has some support for this.
>>> cprop.c -- see references to implicit_sets.
>>
>> cse too: record_jump_equiv.
>
>
> On 09/29/11 17:36, Jeff Law wrote:
> > On 09/29/11 09:26, Bernd Schmidt wrote:
> >> ISTR cse.c has some support for this.
> > cprop.c -- see references to implicit_sets.
>
> cse too: record_jump_equiv.
Interesting. Are the two approaches subtly different
or do they apply precisely the same pred
On 09/29/11 17:36, Jeff Law wrote:
> On 09/29/11 09:26, Bernd Schmidt wrote:
>> ISTR cse.c has some support for this.
> cprop.c -- see references to implicit_sets.
cse too: record_jump_equiv.
Bernd
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On 09/29/11 08:43, Rahul Kharche wrote:
>
>> insn 882 : cc <- compare (r684, 0) jump_insn 883 : if
>> (cc != 0) goto insn 46 insn 49: r291 <- r684 ..
>> insn 46
>>
>> cc contains the result of subtracting 0 from r684; contro
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On 09/29/11 09:26, Bernd Schmidt wrote:
> On 09/29/11 16:43, Rahul Kharche wrote:
>>
>>> insn 882 : cc <- compare (r684, 0) jump_insn 883 : if
>>> (cc != 0) goto insn 46 insn 49: r291 <- r684
>>> .. insn 46
>>>
>>> cc contai
On 09/29/11 16:43, Rahul Kharche wrote:
>
>> insn 882 : cc <- compare (r684, 0)
>> jump_insn 883 : if (cc != 0) goto insn 46
>> insn 49: r291 <- r684
>> ..
>> insn 46
>>
>> cc contains the result of subtracting 0 from r684; control flow goes to
>> insn_49 only if (cc == 0)
> insn 882 : cc <- compare (r684, 0)
> jump_insn 883 : if (cc != 0) goto insn 46
> insn 49: r291 <- r684
> ..
> insn 46
>
> cc contains the result of subtracting 0 from r684; control flow goes to
> insn_49 only if (cc == 0), which implies (r684 == 0).
> Then at insn_49 we
> Unless there's something arch specific related to arm, insn 882 is a
> compare, which won't change r684. Why do you think 0 should
> propagated to r291 if r684 is not zero?
>
Thanks for replying.
Sorry if I misunderstood anything below, and please correct me.
insn 882 : cc <- compare (
"Amker.Cheng" writes:
> (insn 882 881 883 96 (set (reg:CC 24 cc)
> (compare:CC (reg:SI 684 [ default_num_contexts ])
> (const_int 0 [0]))) core_main.c:265 211 {*arm_cmpsi_insn}
> (nil))
>
>
> The insn49 should be propagated with conditional const from insn882
> and jump_i
On Tue, Sep 27, 2011 at 4:19 PM, Amker.Cheng wrote:
> Hi,
> I ran into a case and found conditional (const) propagation is
> mishandled in cprop pass.
> With following insn sequence after cprop1 pass:
>
> (note 878 877 880 96 [bb 96] NOTE_INSN_B
Hi,
I ran into a case and found conditional (const) propagation is
mishandled in cprop pass.
With following insn sequence after cprop1 pass:
(note 878 877 880 96 [bb 96] NOTE_INSN_BASIC_BLOCK)
(insn 882 881 883 96 (set (reg:CC 24 cc)
(co
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