[Qemu-devel] [Bug 1464611] [NEW] 4 * redundant conditions

[Qemu-devel] [Bug 1464611] [NEW] 4 * redundant conditions

[dcb]

Public bug reported:


1.

[qemu/hw/block/nvme.c:355]: (style) Redundant condition: sqid. 'A && (!A
|| B)' is equivalent to 'A || B'

  if (!sqid || (sqid && !nvme_check_sqid(n, sqid))) {

2.

[qemu/hw/block/nvme.c:429]: (style) Redundant condition: cqid. 'A && (!A
|| B)' is equivalent to 'A || B'

  if (!cqid || (cqid && !nvme_check_cqid(n, cqid))) {

3.

[qemu/hw/tpm/tpm_passthrough.c:157]: (style) Redundant condition:
tpm_pt.tpm_op_canceled. 'A && (!A || B)' is equivalent to 'A || B'

     if (!tpm_pt->tpm_op_canceled ||
            (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {

4.

[qemu/target-arm/translate-a64.c:5729]: (style) Redundant condition:
size<3. 'A && (!A || B)' is equivalent to 'A || B'

      if (size > 3
            || (size < 3 && is_q)
            || (size == 3 && !is_q)) {

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1464611

Title:
  4 * redundant conditions

Status in QEMU:
  New

Bug description:
  
  1.

  [qemu/hw/block/nvme.c:355]: (style) Redundant condition: sqid. 'A &&
  (!A || B)' is equivalent to 'A || B'

    if (!sqid || (sqid && !nvme_check_sqid(n, sqid))) {

  2.

  [qemu/hw/block/nvme.c:429]: (style) Redundant condition: cqid. 'A &&
  (!A || B)' is equivalent to 'A || B'

    if (!cqid || (cqid && !nvme_check_cqid(n, cqid))) {

  3.

  [qemu/hw/tpm/tpm_passthrough.c:157]: (style) Redundant condition:
  tpm_pt.tpm_op_canceled. 'A && (!A || B)' is equivalent to 'A || B'

       if (!tpm_pt->tpm_op_canceled ||
              (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {

  4.

  [qemu/target-arm/translate-a64.c:5729]: (style) Redundant condition:
  size<3. 'A && (!A || B)' is equivalent to 'A || B'

        if (size > 3
              || (size < 3 && is_q)
              || (size == 3 && !is_q)) {

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Re: [Qemu-devel] [Bug 1464611] [NEW] 4 * redundant conditions

[Peter Maydell]

On 12 June 2015 at 11:38, dcb <1464611@bugs.launchpad.net> wrote:
> Public bug reported:
>
>
> 1.
>
> [qemu/hw/block/nvme.c:355]: (style) Redundant condition: sqid. 'A && (!A
> || B)' is equivalent to 'A || B'
>
>   if (!sqid || (sqid && !nvme_check_sqid(n, sqid))) {
>
> 2.
>
> [qemu/hw/block/nvme.c:429]: (style) Redundant condition: cqid. 'A && (!A
> || B)' is equivalent to 'A || B'
>
>   if (!cqid || (cqid && !nvme_check_cqid(n, cqid))) {
>
> 3.
>
> [qemu/hw/tpm/tpm_passthrough.c:157]: (style) Redundant condition:
> tpm_pt.tpm_op_canceled. 'A && (!A || B)' is equivalent to 'A || B'
>
>      if (!tpm_pt->tpm_op_canceled ||
>             (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {

These three are all straightforward and would look simpler
in their simplified versions...

> 4.
>
> [qemu/target-arm/translate-a64.c:5729]: (style) Redundant condition:
> size<3. 'A && (!A || B)' is equivalent to 'A || B'
>
>       if (size > 3
>             || (size < 3 && is_q)
>             || (size == 3 && !is_q)) {

...but I'm less sure about this one. I'm not even sure
what it's trying to suggest this should simplify to:
just dropping "size < 3" is obviously wrong, and the
condition format isn't "A && (!A || B)" either.

thanks
-- PMM

Re: [Qemu-devel] [Bug 1464611] [NEW] 4 * redundant conditions

[Eric Blake]

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On 06/12/2015 05:01 AM, Peter Maydell wrote:

>> 4.
>>
>> [qemu/target-arm/translate-a64.c:5729]: (style) Redundant condition:
>> size<3. 'A && (!A || B)' is equivalent to 'A || B'
>>
>>       if (size > 3
>>             || (size < 3 && is_q)
>>             || (size == 3 && !is_q)) {
> 
> ...but I'm less sure about this one. I'm not even sure
> what it's trying to suggest this should simplify to:
> just dropping "size < 3" is obviously wrong, and the
> condition format isn't "A && (!A || B)" either.

Let's break it down into the 6 possibilities based on the binary *
ternary conditions being checked:

> 3, is_q   => accept
> 3, !is_q  => accept
== 3, is_q  => reject
== 3, !is_q => accept
< 3, is_q   => accept
< 3, !is_q  => reject

Here's a shorter conditional with the same properties, but it's gross:

if (size > 3 || (is_q != (size == 3))) {

Too much mental thought to prove it accepts the same set of conditions.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [Bug 1464611] [NEW] 4 * redundant conditions

[Peter Maydell]

On 12 June 2015 at 14:03, Eric Blake <eblake@redhat.com> wrote:
> On 06/12/2015 05:01 AM, Peter Maydell wrote:
>
>>> 4.
>>>
>>> [qemu/target-arm/translate-a64.c:5729]: (style) Redundant condition:
>>> size<3. 'A && (!A || B)' is equivalent to 'A || B'
>>>
>>>       if (size > 3
>>>             || (size < 3 && is_q)
>>>             || (size == 3 && !is_q)) {
>>
>> ...but I'm less sure about this one. I'm not even sure
>> what it's trying to suggest this should simplify to:
>> just dropping "size < 3" is obviously wrong, and the
>> condition format isn't "A && (!A || B)" either.
>
> Let's break it down into the 6 possibilities based on the binary *
> ternary conditions being checked:
>
>> 3, is_q   => accept
>> 3, !is_q  => accept
> == 3, is_q  => reject
> == 3, !is_q => accept
> < 3, is_q   => accept
> < 3, !is_q  => reject
>
> Here's a shorter conditional with the same properties, but it's gross:
>
> if (size > 3 || (is_q != (size == 3))) {
>
> Too much mental thought to prove it accepts the same set of conditions.

Yeah, I think this is the kind of thing where I say "the compiler
should do this simplification if it cares enough" :-)

-- PMM

[Qemu-devel] [Bug 1464611] Re: 4 * redundant conditions

[dcb]

>These three are all straightforward and would look simpler
>in their simplified versions...

Agreed. The first 3 look valid candidates for simplification.

> 4.
>
> [qemu/target-arm/translate-a64.c:5729]: (style) Redundant condition:
> size<3. 'A && (!A || B)' is equivalent to 'A || B'
>
>       if (size > 3
>             || (size < 3 && is_q)
>             || (size == 3 && !is_q)) {

>...but I'm less sure about this one.

Me too. Suggest regard as a false positive from the static analysis tool
and so leave the original code alone.

-- 
You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1464611

Title:
  4 * redundant conditions

Status in QEMU:
  New

Bug description:
  
  1.

  [qemu/hw/block/nvme.c:355]: (style) Redundant condition: sqid. 'A &&
  (!A || B)' is equivalent to 'A || B'

    if (!sqid || (sqid && !nvme_check_sqid(n, sqid))) {

  2.

  [qemu/hw/block/nvme.c:429]: (style) Redundant condition: cqid. 'A &&
  (!A || B)' is equivalent to 'A || B'

    if (!cqid || (cqid && !nvme_check_cqid(n, cqid))) {

  3.

  [qemu/hw/tpm/tpm_passthrough.c:157]: (style) Redundant condition:
  tpm_pt.tpm_op_canceled. 'A && (!A || B)' is equivalent to 'A || B'

       if (!tpm_pt->tpm_op_canceled ||
              (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {

  4.

  [qemu/target-arm/translate-a64.c:5729]: (style) Redundant condition:
  size<3. 'A && (!A || B)' is equivalent to 'A || B'

        if (size > 3
              || (size < 3 && is_q)
              || (size == 3 && !is_q)) {

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[Qemu-devel] [Bug 1464611] Re: 4 * redundant conditions

[Thomas Huth]

Patches have been committed:
http://git.qemu.org/?p=qemu.git;a=commitdiff;h=f96fe6b5c27b9a66dba71
http://git.qemu.org/?p=qemu.git;a=commitdiff;h=5f333d79a4337b390fa41

** Changed in: qemu
       Status: New => Fix Committed

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1464611

Title:
  4 * redundant conditions

Status in QEMU:
  Fix Committed

Bug description:
  
  1.

  [qemu/hw/block/nvme.c:355]: (style) Redundant condition: sqid. 'A &&
  (!A || B)' is equivalent to 'A || B'

    if (!sqid || (sqid && !nvme_check_sqid(n, sqid))) {

  2.

  [qemu/hw/block/nvme.c:429]: (style) Redundant condition: cqid. 'A &&
  (!A || B)' is equivalent to 'A || B'

    if (!cqid || (cqid && !nvme_check_cqid(n, cqid))) {

  3.

  [qemu/hw/tpm/tpm_passthrough.c:157]: (style) Redundant condition:
  tpm_pt.tpm_op_canceled. 'A && (!A || B)' is equivalent to 'A || B'

       if (!tpm_pt->tpm_op_canceled ||
              (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {

  4.

  [qemu/target-arm/translate-a64.c:5729]: (style) Redundant condition:
  size<3. 'A && (!A || B)' is equivalent to 'A || B'

        if (size > 3
              || (size < 3 && is_q)
              || (size == 3 && !is_q)) {

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[Qemu-devel] [Bug 1464611] Re: 4 * redundant conditions

[Thomas Huth]

Released with version 2.8

** Changed in: qemu
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1464611

Title:
  4 * redundant conditions

Status in QEMU:
  Fix Released

Bug description:
  
  1.

  [qemu/hw/block/nvme.c:355]: (style) Redundant condition: sqid. 'A &&
  (!A || B)' is equivalent to 'A || B'

    if (!sqid || (sqid && !nvme_check_sqid(n, sqid))) {

  2.

  [qemu/hw/block/nvme.c:429]: (style) Redundant condition: cqid. 'A &&
  (!A || B)' is equivalent to 'A || B'

    if (!cqid || (cqid && !nvme_check_cqid(n, cqid))) {

  3.

  [qemu/hw/tpm/tpm_passthrough.c:157]: (style) Redundant condition:
  tpm_pt.tpm_op_canceled. 'A && (!A || B)' is equivalent to 'A || B'

       if (!tpm_pt->tpm_op_canceled ||
              (tpm_pt->tpm_op_canceled && errno != ECANCELED)) {

  4.

  [qemu/target-arm/translate-a64.c:5729]: (style) Redundant condition:
  size<3. 'A && (!A || B)' is equivalent to 'A || B'

        if (size > 3
              || (size < 3 && is_q)
              || (size == 3 && !is_q)) {

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