[cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Markus Elfring]

Hello,

I got into the mood to try another simple source code transformation out which
can be achieved also by the means of the semantic patch language.

@replacement@
expression object, size, source, target;
@@
 target =
-         object;
 memcpy(
-       target
+       object
        , source,
        size);


Test result (according to the software combination “Coccinelle 1.3.0”):
Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --timeout 23 -j4 --chunksize 1 --no-loops -dir . …/Projekte/Coccinelle/janitor/use_memcpy_assignment.cocci > …/Projekte/Bau/Linux/scripts/Coccinelle/use_memcpy_assignment-no_loops-20251029.diff 2> …/Projekte/Bau/Linux/scripts/Coccinelle/use_memcpy_assignment-no_loops-errors-20251029.txt
real    5m35,579s
user    20m20,037s
sys     0m14,467s


It can be determined then from the generated diff file that mentioned
implementation details can be transformed in 304 source files at the moment.
Thus I became curious if it would be supported to adjust any places there
according to (Linux) coding style preferences.

Regards,
Markus

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Julia Lawall]

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On Wed, 29 Oct 2025, Markus Elfring wrote:

> Hello,
>
> I got into the mood to try another simple source code transformation out which
> can be achieved also by the means of the semantic patch language.
>
> @replacement@
> expression object, size, source, target;
> @@
>  target =
> -         object;
>  memcpy(
> -       target
> +       object
>         , source,
>         size);
>
>
> Test result (according to the software combination “Coccinelle 1.3.0”):
> Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --timeout 23 -j4 --chunksize 1 --no-loops -dir . …/Projekte/Coccinelle/janitor/use_memcpy_assignment.cocci > …/Projekte/Bau/Linux/scripts/Coccinelle/use_memcpy_assignment-no_loops-20251029.diff 2> …/Projekte/Bau/Linux/scripts/Coccinelle/use_memcpy_assignment-no_loops-errors-20251029.txt
> real    5m35,579s
> user    20m20,037s
> sys     0m14,467s
>
>
> It can be determined then from the generated diff file that mentioned
> implementation details can be transformed in 304 source files at the moment.
> Thus I became curious if it would be supported to adjust any places there
> according to (Linux) coding style preferences.

If you have a concern, you have to say what it is.  It doesn't seem it is
about the running time, so why do you include that information?

I should not have to repeat your experiment to figure out what you are
asking about.

julia

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Markus Elfring]

>> It can be determined then from the generated diff file that mentioned
>> implementation details can be transformed in 304 source files at the moment.
>> Thus I became curious if it would be supported to adjust any places there
>> according to (Linux) coding style preferences.
> 
> If you have a concern, you have to say what it is.

I expressed something for further development considerations.
The source code analysis result can be interpreted in some directions.


>                                                     It doesn't seem it is
> about the running time,

Not directly in this case.


>                         so why do you include that information?

Further software users can compare such a measurement with other observations.


> I should not have to repeat your experiment to figure out what you are
> asking about.

You can recognise recurring development challenges, can't you?

* Change resistance

* Varying coding style preferences

* Code improvement possibilities

* Development resources

* Pretty-printing issues


Another test result representation for your convenience:
https://elixir.bootlin.com/linux/v6.18-rc3/source/arch/arm64/kvm/arm.c#L2554-L2726

Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment.cocci arch/arm64/kvm/arm.c
…
@@ -2600,8 +2600,8 @@ static int __init init_hyp_mode(void)
                        goto out_err;
                }
 
-               page_addr = page_address(page);
-               memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
+               page_addr =
+               memcpy(page_address(page), CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
                kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] = (unsigned long)page_addr;
        }
 

real    0m0,606s
user    0m0,576s
sys     0m0,030s



Another SmPL script example might become helpful.

@replacement2@
expression object, size, source, target;
@@
 target =
-         object; memcpy(target, source, size)
+         memcpy(object, source, size)
 ;


Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment2.cocci arch/arm64/kvm/arm.c
…
@@ -2600,8 +2600,8 @@ static int __init init_hyp_mode(void)
                        goto out_err;
                }
 
-               page_addr = page_address(page);
-               memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
+               page_addr =memcpy(page_address(page), CHOOSE_NVHE_SYM(__per_cpu_start),
+                                 nvhe_percpu_size());
                kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] = (unsigned long)page_addr;
        }
 

real    0m0,626s
user    0m0,588s
sys     0m0,037s


Regards,
Markus

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Julia Lawall]

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On Thu, 30 Oct 2025, Markus Elfring wrote:

> >> It can be determined then from the generated diff file that mentioned
> >> implementation details can be transformed in 304 source files at the moment.
> >> Thus I became curious if it would be supported to adjust any places there
> >> according to (Linux) coding style preferences.
> >
> > If you have a concern, you have to say what it is.
>
> I expressed something for further development considerations.
> The source code analysis result can be interpreted in some directions.
>
>
> >                                                     It doesn't seem it is
> > about the running time,
>
> Not directly in this case.
>
>
> >                         so why do you include that information?
>
> Further software users can compare such a measurement with other observations.
>
>
> > I should not have to repeat your experiment to figure out what you are
> > asking about.
>
> You can recognise recurring development challenges, can't you?
>
> * Change resistance
>
> * Varying coding style preferences
>
> * Code improvement possibilities
>
> * Development resources
>
> * Pretty-printing issues
>
>
> Another test result representation for your convenience:
> https://elixir.bootlin.com/linux/v6.18-rc3/source/arch/arm64/kvm/arm.c#L2554-L2726
>
> Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment.cocci arch/arm64/kvm/arm.c
> …
> @@ -2600,8 +2600,8 @@ static int __init init_hyp_mode(void)
>                         goto out_err;
>                 }
>
> -               page_addr = page_address(page);
> -               memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
> +               page_addr =
> +               memcpy(page_address(page), CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
>                 kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] = (unsigned long)page_addr;

This is all I wanted.  The rest is complete noise.

I think you would get a more satisfactory result by just removing all of
the code and adding it back. Then Coccinelle would take charge of laying
out the whole thing.

thanks,
julia

>         }
>
>
> real    0m0,606s
> user    0m0,576s
> sys     0m0,030s
>
>
>
> Another SmPL script example might become helpful.
>
> @replacement2@
> expression object, size, source, target;
> @@
>  target =
> -         object; memcpy(target, source, size)
> +         memcpy(object, source, size)
>  ;
>
>
> Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment2.cocci arch/arm64/kvm/arm.c
> …
> @@ -2600,8 +2600,8 @@ static int __init init_hyp_mode(void)
>                         goto out_err;
>                 }
>
> -               page_addr = page_address(page);
> -               memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
> +               page_addr =memcpy(page_address(page), CHOOSE_NVHE_SYM(__per_cpu_start),
> +                                 nvhe_percpu_size());
>                 kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] = (unsigned long)page_addr;
>         }
>
>
> real    0m0,626s
> user    0m0,588s
> sys     0m0,037s
>
>
> Regards,
> Markus
>

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Markus Elfring]

…> I think you would get a more satisfactory result by just removing all of
> the code and adding it back. Then Coccinelle would take charge of laying
> out the whole thing.
…

See also once more:

>> Another SmPL script example might become helpful.
>>
>> @replacement2@
>> expression object, size, source, target;
>> @@
>>  target =
>> -         object; memcpy(target, source, size)
>> +         memcpy(object, source, size)
>>  ;
>>
>>
>> Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment2.cocci arch/arm64/kvm/arm.c
…>> real    0m0,626s
>> user    0m0,588s
>> sys     0m0,037s


Regards,
Markus

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Julia Lawall]

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On Thu, 30 Oct 2025, Markus Elfring wrote:

> …> I think you would get a more satisfactory result by just removing all of
> > the code and adding it back. Then Coccinelle would take charge of laying
> > out the whole thing.
> …
>
> See also once more:
>
> >> Another SmPL script example might become helpful.
> >>
> >> @replacement2@
> >> expression object, size, source, target;
> >> @@
> >>  target =
> >> -         object; memcpy(target, source, size)
> >> +         memcpy(object, source, size)
> >>  ;

I said to remove everything.  target = also.

julia

> >>
> >>
> >> Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment2.cocci arch/arm64/kvm/arm.c
> …>> real    0m0,626s
> >> user    0m0,588s
> >> sys     0m0,037s
>
>
> Regards,
> Markus
>

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Markus Elfring]

> If you have a concern, you have to say what it is.  It doesn't seem it is
> about the running time, so why do you include that information?

How will remaining open issues be resolved?


> I should not have to repeat your experiment

It would be nice if further software users would occasionally reproduce
presented data processing possibilities.


>                                             to figure out what you are
> asking about.

I “accidentally” tried also the following SmPL script variants out.

A)
@replacement3@
expression object, size, source, target;
@@
 target =
-object; memcpy(target, source, size)
+object; memcpy(object, source, size)
 ;

Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment3.cocci arch/arm64/kvm/arm.c
…
@@ -2600,8 +2600,8 @@ static int __init init_hyp_mode(void)
                        goto out_err;
                }
 
-               page_addr = page_address(page);
-               memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
+               page_addr =memcpy(page_address(page), CHOOSE_NVHE_SYM(__per_cpu_start),
+                                 nvhe_percpu_size());page_address(page);
                kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] = (unsigned long)page_addr;
        }
 

real    0m0,578s
user    0m0,524s
sys     0m0,047s



B)
@replacement4@
expression object, size, source, target;
@@
-target = object; memcpy(target, source, size)
+target = object; memcpy(object, source, size)
 ;

Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment4.cocci arch/arm64/kvm/arm.c
…
@@ -2600,8 +2600,8 @@ static int __init init_hyp_mode(void)
                        goto out_err;
                }
 
+               memcpy(page_address(page), CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
                page_addr = page_address(page);
-               memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
                kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] = (unsigned long)page_addr;
        }
 

real    0m0,565s
user    0m0,533s
sys     0m0,032s



Would you like to reconsider implementation details accordingly?

Regards,
Markus

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Julia Lawall]

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On Thu, 30 Oct 2025, Markus Elfring wrote:

> > If you have a concern, you have to say what it is.  It doesn't seem it is
> > about the running time, so why do you include that information?
>
> How will remaining open issues be resolved?
>
>
> > I should not have to repeat your experiment
>
> It would be nice if further software users would occasionally reproduce
> presented data processing possibilities.
>
>
> >                                             to figure out what you are
> > asking about.
>
> I “accidentally” tried also the following SmPL script variants out.
>
> A)
> @replacement3@
> expression object, size, source, target;
> @@
>  target =
> -object; memcpy(target, source, size)
> +object; memcpy(object, source, size)
>  ;
>
> Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment3.cocci arch/arm64/kvm/arm.c
> …
> @@ -2600,8 +2600,8 @@ static int __init init_hyp_mode(void)
>                         goto out_err;
>                 }
>
> -               page_addr = page_address(page);
> -               memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
> +               page_addr =memcpy(page_address(page), CHOOSE_NVHE_SYM(__per_cpu_start),
> +                                 nvhe_percpu_size());page_address(page);
>                 kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] = (unsigned long)page_addr;
>         }
>
>
> real    0m0,578s
> user    0m0,524s
> sys     0m0,047s
>
>
>
> B)
> @replacement4@
> expression object, size, source, target;
> @@
> -target = object; memcpy(target, source, size)
> +target = object; memcpy(object, source, size)
>  ;
>
> Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment4.cocci arch/arm64/kvm/arm.c
> …
> @@ -2600,8 +2600,8 @@ static int __init init_hyp_mode(void)
>                         goto out_err;
>                 }
>
> +               memcpy(page_address(page), CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
>                 page_addr = page_address(page);
> -               memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
>                 kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] = (unsigned long)page_addr;
>         }

Not sure what is the point of all this.  Try:

- target = object; memcpy(target, source, size);
+ target = memcpy(target, source, size);

Then it will add newlines in the argument of memcpy if needed to stay in a
reasonable number of columns.

julia

>
>
> real    0m0,565s
> user    0m0,533s
> sys     0m0,032s
>
>
>
> Would you like to reconsider implementation details accordingly?
>
> Regards,
> Markus
>

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Markus Elfring]

>> I “accidentally” tried also the following SmPL script variants out.
>>
>> A)
>> @replacement3@
>> expression object, size, source, target;
>> @@
>>  target =
>> -object; memcpy(target, source, size)
>> +object; memcpy(object, source, size)
>>  ;
>>
>> Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment3.cocci arch/arm64/kvm/arm.c
>> …
>> @@ -2600,8 +2600,8 @@ static int __init init_hyp_mode(void)
>>                         goto out_err;
>>                 }
>>
>> -               page_addr = page_address(page);
>> -               memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
>> +               page_addr =memcpy(page_address(page), CHOOSE_NVHE_SYM(__per_cpu_start),
>> +                                 nvhe_percpu_size());page_address(page);
>>                 kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] = (unsigned long)page_addr;
>>         }
…>> B)
>> @replacement4@
>> expression object, size, source, target;
>> @@
>> -target = object; memcpy(target, source, size)
>> +target = object; memcpy(object, source, size)
>>  ;
>>
>> Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment4.cocci arch/arm64/kvm/arm.c
>> …
>> @@ -2600,8 +2600,8 @@ static int __init init_hyp_mode(void)
>>                         goto out_err;
>>                 }
>>
>> +               memcpy(page_address(page), CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
>>                 page_addr = page_address(page);
>> -               memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
>>                 kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] = (unsigned long)page_addr;
>>         }
> 
> Not sure what is the point of all this.  Try:
…

Would you like to acknowledge that undesirable difference displays were generated anyhow
for these test cases?


>> Would you like to reconsider implementation details accordingly?

Are we looking for corresponding software improvements?

Regards,
Markus

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Julia Lawall]

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On Thu, 30 Oct 2025, Markus Elfring wrote:

> >> I “accidentally” tried also the following SmPL script variants out.
> >>
> >> A)
> >> @replacement3@
> >> expression object, size, source, target;
> >> @@
> >>  target =
> >> -object; memcpy(target, source, size)
> >> +object; memcpy(object, source, size)
> >>  ;
> >>
> >> Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment3.cocci arch/arm64/kvm/arm.c
> >> …
> >> @@ -2600,8 +2600,8 @@ static int __init init_hyp_mode(void)
> >>                         goto out_err;
> >>                 }
> >>
> >> -               page_addr = page_address(page);
> >> -               memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
> >> +               page_addr =memcpy(page_address(page), CHOOSE_NVHE_SYM(__per_cpu_start),
> >> +                                 nvhe_percpu_size());page_address(page);
> >>                 kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] = (unsigned long)page_addr;
> >>         }
> …>> B)
> >> @replacement4@
> >> expression object, size, source, target;
> >> @@
> >> -target = object; memcpy(target, source, size)
> >> +target = object; memcpy(object, source, size)
> >>  ;
> >>
> >> Markus_Elfring@Sonne:…/Projekte/Linux/next-analyses> time /usr/bin/spatch --max-width 100 --no-loops …/Projekte/Coccinelle/janitor/use_memcpy_assignment4.cocci arch/arm64/kvm/arm.c
> >> …
> >> @@ -2600,8 +2600,8 @@ static int __init init_hyp_mode(void)
> >>                         goto out_err;
> >>                 }
> >>
> >> +               memcpy(page_address(page), CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
> >>                 page_addr = page_address(page);
> >> -               memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
> >>                 kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] = (unsigned long)page_addr;
> >>         }
> >
> > Not sure what is the point of all this.  Try:
> …
>
> Would you like to acknowledge that undesirable difference displays were generated anyhow
> for these test cases?

Sure.

>
>
> >> Would you like to reconsider implementation details accordingly?
>
> Are we looking for corresponding software improvements?

If time permits.

julia

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Dan Carpenter]

On Thu, Oct 30, 2025 at 01:31:49PM +0100, Julia Lawall wrote:
> 
> 
> On Thu, 30 Oct 2025, Markus Elfring wrote:
> > @@ -2600,8 +2600,8 @@ static int __init init_hyp_mode(void)
> >                         goto out_err;
> >                 }
> >
> > +               memcpy(page_address(page), CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
> >                 page_addr = page_address(page);
> > -               memcpy(page_addr, CHOOSE_NVHE_SYM(__per_cpu_start), nvhe_percpu_size());
> >                 kvm_nvhe_sym(kvm_arm_hyp_percpu_base)[cpu] = (unsigned long)page_addr;
> >         }
> 
> Not sure what is the point of all this.  Try:
> 
> - target = object; memcpy(target, source, size);
> + target = memcpy(target, source, size);

No one will thank you for making these changes...  :(  Please don't do
it.

regards,
dan carpenter

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Markus Elfring]

>> - target = object; memcpy(target, source, size);
+ target = memcpy(object, source, size);


> No one will thank you for making these changes...  🙁

Will any more contributors dare to try adjustments out at such source code places?


>                                                        Please don't do it.

How will change tolerance evolve further?

Regards,
Markus

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Markus Elfring]

> If you have a concern, you have to say what it is.  It doesn't seem it is
> about the running time, so why do you include that information?

How will the chances evolve to integrate another coccicheck script for
the discussed source code transformation approach?

Regards,
Markus

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Julia Lawall]

On Thu, 30 Oct 2025, Markus Elfring wrote:

> > If you have a concern, you have to say what it is.  It doesn't seem it is
> > about the running time, so why do you include that information?
>
> How will the chances evolve to integrate another coccicheck script for
> the discussed source code transformation approach?

No chance, given Dan's negative feedback.

julia

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Markus Elfring]

> No chance, given Dan's negative feedback.

Will any additional arguments become more convincing for change possibilities?

Regards,
Markus

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Markus Elfring]

> No one will thank you for making these changes...  :(  Please don't do it.

I am curious if further developers would dare to try another source code search pattern out.

@display@
expression destination, size, source, target;
@@
*target = memcpy(destination, source, size);


I would like to point out that return values from memcpy() calls are assigned
to variables in 16 source files of the software “Linux next-20251030”.

Under which circumstances can development interests grow to reduce “unused”
return values also for this kind of function?
https://wiki.sei.cmu.edu/confluence/display/c/MSC13-C.+Detect+and+remove+unused+values

Regards,
Markus

Re: [cocci] [RFC] Increasing usage of direct pointer assignments from memcpy() calls with SmPL?

[Markus Elfring]

> If you have a concern, you have to say what it is.

The initial search pattern might be too simple so far.
Thus I became interested in further software extensions also according to
the discussed source code transformation approach.
Can it be determined anyhow (by the means of the semantic patch language)
that the variable from the assignment statement would not be used any more
after the adjustment within the affected scope?

Regards,
Markus