[PATCH] hw/openrisc/openrisc_sim: Add assertion to silent GCC warning

[PATCH] hw/openrisc/openrisc_sim: Add assertion to silent GCC warning

[Philippe Mathieu-Daudé]

When compiling with GCC 10 (Fedora 32) using CFLAGS=-O2 we get:

    CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
  hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
  hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
     87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
        |                                  ~~~~~~~~^~~

While humans can tell smp_cpus will always be in the [1, 2] range,
(openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
can't.

Add an assertion to give the compiler a hint there's no use of
uninitialized data.

Buglink: https://bugs.launchpad.net/qemu/+bug/1874073
Reported-by: Martin Liška <mliska@suse.cz>
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 hw/openrisc/openrisc_sim.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
index d08ce61811..02f5259e5e 100644
--- a/hw/openrisc/openrisc_sim.c
+++ b/hw/openrisc/openrisc_sim.c
@@ -134,6 +134,7 @@ static void openrisc_sim_init(MachineState *machine)
     int n;
     unsigned int smp_cpus = machine->smp.cpus;
 
+    assert(smp_cpus >= 1 && smp_cpus <= 2);
     for (n = 0; n < smp_cpus; n++) {
         cpu = OPENRISC_CPU(cpu_create(machine->cpu_type));
         if (cpu == NULL) {
-- 
2.21.3

[Bug 1874073] [PATCH] hw/openrisc/openrisc_sim: Add assertion to silent GCC warning

[Philippe Mathieu-Daudé]

When compiling with GCC 10 (Fedora 32) using CFLAGS=-O2 we get:

    CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
  hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
  hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
     87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
        |                                  ~~~~~~~~^~~

While humans can tell smp_cpus will always be in the [1, 2] range,
(openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
can't.

Add an assertion to give the compiler a hint there's no use of
uninitialized data.

Buglink: https://bugs.launchpad.net/qemu/+bug/1874073
Reported-by: Martin Liška <mliska@suse.cz>
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 hw/openrisc/openrisc_sim.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
index d08ce61811..02f5259e5e 100644
--- a/hw/openrisc/openrisc_sim.c
+++ b/hw/openrisc/openrisc_sim.c
@@ -134,6 +134,7 @@ static void openrisc_sim_init(MachineState *machine)
     int n;
     unsigned int smp_cpus = machine->smp.cpus;
 
+    assert(smp_cpus >= 1 && smp_cpus <= 2);
     for (n = 0; n < smp_cpus; n++) {
         cpu = OPENRISC_CPU(cpu_create(machine->cpu_type));
         if (cpu == NULL) {
-- 
2.21.3


** Changed in: qemu
     Assignee: (unassigned) => Philippe Mathieu-Daudé (philmd)

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Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  Confirmed

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

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Re: [PATCH] hw/openrisc/openrisc_sim: Add assertion to silent GCC warning

[Thomas Huth]

On 08/06/2020 09.14, Philippe Mathieu-Daudé wrote:
> When compiling with GCC 10 (Fedora 32) using CFLAGS=-O2 we get:
> 
>     CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
>   hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
>   hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>      87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
>         |                                  ~~~~~~~~^~~
> 
> While humans can tell smp_cpus will always be in the [1, 2] range,
> (openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
> can't.
> 
> Add an assertion to give the compiler a hint there's no use of
> uninitialized data.
> 
> Buglink: https://bugs.launchpad.net/qemu/+bug/1874073
> Reported-by: Martin Liška <mliska@suse.cz>
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  hw/openrisc/openrisc_sim.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
> index d08ce61811..02f5259e5e 100644
> --- a/hw/openrisc/openrisc_sim.c
> +++ b/hw/openrisc/openrisc_sim.c
> @@ -134,6 +134,7 @@ static void openrisc_sim_init(MachineState *machine)
>      int n;
>      unsigned int smp_cpus = machine->smp.cpus;
>  
> +    assert(smp_cpus >= 1 && smp_cpus <= 2);
>      for (n = 0; n < smp_cpus; n++) {
>          cpu = OPENRISC_CPU(cpu_create(machine->cpu_type));
>          if (cpu == NULL) {
> 

Reviewed-by: Thomas Huth <thuth@redhat.com>

Re: [PATCH] hw/openrisc/openrisc_sim: Add assertion to silent GCC warning

[Eric Blake]

On 6/8/20 2:14 AM, Philippe Mathieu-Daudé wrote:
> When compiling with GCC 10 (Fedora 32) using CFLAGS=-O2 we get:

In the subject: s/silent/silence/

> 
>      CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
>    hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
>    hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>       87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
>          |                                  ~~~~~~~~^~~
> 
> While humans can tell smp_cpus will always be in the [1, 2] range,
> (openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
> can't.
> 
> Add an assertion to give the compiler a hint there's no use of
> uninitialized data.
> 
> Buglink: https://bugs.launchpad.net/qemu/+bug/1874073
> Reported-by: Martin Liška <mliska@suse.cz>
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>   hw/openrisc/openrisc_sim.c | 1 +
>   1 file changed, 1 insertion(+)

Tested-by: Eric Blake <eblake@redhat.com>

With the typo fixed,
Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

[Bug 1874073] Re: [PATCH] hw/openrisc/openrisc_sim: Add assertion to silent GCC warning

[Eric Blake]

On 6/8/20 2:14 AM, Philippe Mathieu-Daudé wrote:
> When compiling with GCC 10 (Fedora 32) using CFLAGS=-O2 we get:

In the subject: s/silent/silence/

> 
>      CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
>    hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
>    hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>       87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
>          |                                  ~~~~~~~~^~~
> 
> While humans can tell smp_cpus will always be in the [1, 2] range,
> (openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
> can't.
> 
> Add an assertion to give the compiler a hint there's no use of
> uninitialized data.
> 
> Buglink: https://bugs.launchpad.net/qemu/+bug/1874073
> Reported-by: Martin Liška <mliska@suse.cz>
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>   hw/openrisc/openrisc_sim.c | 1 +
>   1 file changed, 1 insertion(+)

Tested-by: Eric Blake <eblake@redhat.com>

With the typo fixed,
Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

-- 
You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1874073

Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  Confirmed

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

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Re: [PATCH] hw/openrisc/openrisc_sim: Add assertion to silent GCC warning

[Stafford Horne]

On Mon, Jun 08, 2020 at 10:33:24AM -0500, Eric Blake wrote:
> On 6/8/20 2:14 AM, Philippe Mathieu-Daudé wrote:
> > When compiling with GCC 10 (Fedora 32) using CFLAGS=-O2 we get:
> 
> In the subject: s/silent/silence/
> 
> > 
> >      CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
> >    hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
> >    hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> >       87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
> >          |                                  ~~~~~~~~^~~
> > 
> > While humans can tell smp_cpus will always be in the [1, 2] range,
> > (openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
> > can't.
> > 
> > Add an assertion to give the compiler a hint there's no use of
> > uninitialized data.
> > 
> > Buglink: https://bugs.launchpad.net/qemu/+bug/1874073
> > Reported-by: Martin Liška <mliska@suse.cz>
> > Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> > Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> > ---
> >   hw/openrisc/openrisc_sim.c | 1 +
> >   1 file changed, 1 insertion(+)
> 
> Tested-by: Eric Blake <eblake@redhat.com>
> 
> With the typo fixed,
> Reviewed-by: Eric Blake <eblake@redhat.com>

Acked-by: Stafford Horne <shorne@gmail.com>

I see there are now two patches for this, I kind of like this assert fix.

Shall I queue it for OpenRISC pulling?  Or can someone else pick this up?

-Stafford

Re: [PATCH] hw/openrisc/openrisc_sim: Add assertion to silent GCC warning

[Stafford Horne]

On Wed, Jun 10, 2020 at 05:42:27AM +0900, Stafford Horne wrote:
> On Mon, Jun 08, 2020 at 10:33:24AM -0500, Eric Blake wrote:
> > On 6/8/20 2:14 AM, Philippe Mathieu-Daudé wrote:
> > > When compiling with GCC 10 (Fedora 32) using CFLAGS=-O2 we get:
> > 
> > In the subject: s/silent/silence/
> > 
> > > 
> > >      CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
> > >    hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
> > >    hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> > >       87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
> > >          |                                  ~~~~~~~~^~~
> > > 
> > > While humans can tell smp_cpus will always be in the [1, 2] range,
> > > (openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
> > > can't.
> > > 
> > > Add an assertion to give the compiler a hint there's no use of
> > > uninitialized data.
> > > 
> > > Buglink: https://bugs.launchpad.net/qemu/+bug/1874073
> > > Reported-by: Martin Liška <mliska@suse.cz>
> > > Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> > > Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> > > ---
> > >   hw/openrisc/openrisc_sim.c | 1 +
> > >   1 file changed, 1 insertion(+)
> > 
> > Tested-by: Eric Blake <eblake@redhat.com>
> > 
> > With the typo fixed,
> > Reviewed-by: Eric Blake <eblake@redhat.com>
> 
> Acked-by: Stafford Horne <shorne@gmail.com>
> 
> I see there are now two patches for this, I kind of like this assert fix.
> 
> Shall I queue it for OpenRISC pulling?  Or can someone else pick this up?

Hello,
Sorry, I see v2 of this patch has already been picked up.

-Stafford

Re: [PATCH] hw/openrisc/openrisc_sim: Add assertion to silent GCC warning

[Eric Blake]

On 6/9/20 3:42 PM, Stafford Horne wrote:

>>> While humans can tell smp_cpus will always be in the [1, 2] range,
>>> (openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
>>> can't.
>>>
>>> Add an assertion to give the compiler a hint there's no use of
>>> uninitialized data.
>>>

> Acked-by: Stafford Horne <shorne@gmail.com>
> 
> I see there are now two patches for this, I kind of like this assert fix.
> 
> Shall I queue it for OpenRISC pulling?  Or can someone else pick this up?

Looks like Laurent already volunteered to queue it through the trivial 
patches tree.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

[Bug 1874073] Re: [PATCH] hw/openrisc/openrisc_sim: Add assertion to silent GCC warning

[Eric Blake]

On 6/9/20 3:42 PM, Stafford Horne wrote:

>>> While humans can tell smp_cpus will always be in the [1, 2] range,
>>> (openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
>>> can't.
>>>
>>> Add an assertion to give the compiler a hint there's no use of
>>> uninitialized data.
>>>

> Acked-by: Stafford Horne <shorne@gmail.com>
> 
> I see there are now two patches for this, I kind of like this assert fix.
> 
> Shall I queue it for OpenRISC pulling?  Or can someone else pick this up?

Looks like Laurent already volunteered to queue it through the trivial 
patches tree.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

-- 
You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1874073

Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  Confirmed

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

To manage notifications about this bug go to:
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[PATCH] or1k: Fix compilation hiccup

[Eric Blake]

On my Fedora 32 machine, gcc 10.1.1 at -O2 (the default for a bare
'./configure') has a false-positive complaint:

  CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
/home/eblake/qemu/hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
/home/eblake/qemu/hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
   87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
      |                                  ~~~~~~~~^~~

Initializing both pointers of cpu_irqs[] to NULL is sufficient to shut
up the compiler, even though they are definitely assigned in
openrisc_sim_init() prior to the inlined call to
openrisc_sim_ompic_init() containing the line in question.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 hw/openrisc/openrisc_sim.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
index d08ce6181199..95011a8015b4 100644
--- a/hw/openrisc/openrisc_sim.c
+++ b/hw/openrisc/openrisc_sim.c
@@ -129,7 +129,7 @@ static void openrisc_sim_init(MachineState *machine)
     const char *kernel_filename = machine->kernel_filename;
     OpenRISCCPU *cpu = NULL;
     MemoryRegion *ram;
-    qemu_irq *cpu_irqs[2];
+    qemu_irq *cpu_irqs[2] = {};
     qemu_irq serial_irq;
     int n;
     unsigned int smp_cpus = machine->smp.cpus;
-- 
2.26.2

Re: [PATCH] or1k: Fix compilation hiccup

[no-reply]

Patchew URL: https://patchew.org/QEMU/20200526185132.1652355-1-eblake@redhat.com/



Hi,

This series seems to have some coding style problems. See output below for
more information:

Message-id: 20200526185132.1652355-1-eblake@redhat.com
Subject: [PATCH] or1k: Fix compilation hiccup
Type: series

=== TEST SCRIPT BEGIN ===
#!/bin/bash
git rev-parse base > /dev/null || exit 0
git config --local diff.renamelimit 0
git config --local diff.renames True
git config --local diff.algorithm histogram
./scripts/checkpatch.pl --mailback base..
=== TEST SCRIPT END ===

Switched to a new branch 'test'
d96d2fb or1k: Fix compilation hiccup

=== OUTPUT BEGIN ===
ERROR: spaces required around that '*' (ctx:WxV)
#33: FILE: hw/openrisc/openrisc_sim.c:132:
+    qemu_irq *cpu_irqs[2] = {};
              ^

total: 1 errors, 0 warnings, 8 lines checked

Commit d96d2fbbc5db (or1k: Fix compilation hiccup) has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.
=== OUTPUT END ===

Test command exited with code: 1


The full log is available at
http://patchew.org/logs/20200526185132.1652355-1-eblake@redhat.com/testing.checkpatch/?type=message.
---
Email generated automatically by Patchew [https://patchew.org/].
Please send your feedback to patchew-devel@redhat.com

Re: [PATCH] or1k: Fix compilation hiccup

[Eric Blake]

On 5/26/20 6:21 PM, no-reply@patchew.org wrote:
> Patchew URL: https://patchew.org/QEMU/20200526185132.1652355-1-eblake@redhat.com/
> 
> 
> 
> Hi,
> 
> This series seems to have some coding style problems. See output below for
> more information:
> 

> === OUTPUT BEGIN ===
> ERROR: spaces required around that '*' (ctx:WxV)
> #33: FILE: hw/openrisc/openrisc_sim.c:132:
> +    qemu_irq *cpu_irqs[2] = {};
>                ^
> 
> total: 1 errors, 0 warnings, 8 lines checked
> 
> Commit d96d2fbbc5db (or1k: Fix compilation hiccup) has style problems, please review.  If any of these errors
> are false positives report them to the maintainer, see
> CHECKPATCH in MAINTAINERS.

False positive, due to 'qemu_irq' not following the normal naming 
conventions for typedefs.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

Re: [PATCH] or1k: Fix compilation hiccup

[Thomas Huth]

On 26/05/2020 20.51, Eric Blake wrote:
> On my Fedora 32 machine, gcc 10.1.1 at -O2 (the default for a bare
> './configure') has a false-positive complaint:
> 
>   CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
> /home/eblake/qemu/hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
> /home/eblake/qemu/hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>    87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
>       |                                  ~~~~~~~~^~~
> 
> Initializing both pointers of cpu_irqs[] to NULL is sufficient to shut
> up the compiler, even though they are definitely assigned in
> openrisc_sim_init() prior to the inlined call to
> openrisc_sim_ompic_init() containing the line in question.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>  hw/openrisc/openrisc_sim.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
> index d08ce6181199..95011a8015b4 100644
> --- a/hw/openrisc/openrisc_sim.c
> +++ b/hw/openrisc/openrisc_sim.c
> @@ -129,7 +129,7 @@ static void openrisc_sim_init(MachineState *machine)
>      const char *kernel_filename = machine->kernel_filename;
>      OpenRISCCPU *cpu = NULL;
>      MemoryRegion *ram;
> -    qemu_irq *cpu_irqs[2];
> +    qemu_irq *cpu_irqs[2] = {};
>      qemu_irq serial_irq;
>      int n;
>      unsigned int smp_cpus = machine->smp.cpus;
> 

Reviewed-by: Thomas Huth <thuth@redhat.com>

Re: [PATCH] or1k: Fix compilation hiccup

[Philippe Mathieu-Daudé]

On 5/26/20 8:51 PM, Eric Blake wrote:
> On my Fedora 32 machine, gcc 10.1.1 at -O2 (the default for a bare
> './configure') has a false-positive complaint:
> 
>   CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
> /home/eblake/qemu/hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
> /home/eblake/qemu/hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>    87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
>       |                                  ~~~~~~~~^~~
> 
> Initializing both pointers of cpu_irqs[] to NULL is sufficient to shut
> up the compiler, even though they are definitely assigned in
> openrisc_sim_init() prior to the inlined call to
> openrisc_sim_ompic_init() containing the line in question.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>  hw/openrisc/openrisc_sim.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
> index d08ce6181199..95011a8015b4 100644
> --- a/hw/openrisc/openrisc_sim.c
> +++ b/hw/openrisc/openrisc_sim.c
> @@ -129,7 +129,7 @@ static void openrisc_sim_init(MachineState *machine)
>      const char *kernel_filename = machine->kernel_filename;
>      OpenRISCCPU *cpu = NULL;
>      MemoryRegion *ram;
> -    qemu_irq *cpu_irqs[2];
> +    qemu_irq *cpu_irqs[2] = {};

Ah I now remembered why this warning sound familiar:
https://bugs.launchpad.net/qemu/+bug/1874073

Peter suggested a different fix, I tested it, and was expecting Martin
Liska to post an updated patch.

>      qemu_irq serial_irq;
>      int n;
>      unsigned int smp_cpus = machine->smp.cpus;
> 

[Bug 1874073] Re: [PATCH] or1k: Fix compilation hiccup

[Philippe Mathieu-Daudé]

On 5/26/20 8:51 PM, Eric Blake wrote:
> On my Fedora 32 machine, gcc 10.1.1 at -O2 (the default for a bare
> './configure') has a false-positive complaint:
> 
>   CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
> /home/eblake/qemu/hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
> /home/eblake/qemu/hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>    87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
>       |                                  ~~~~~~~~^~~
> 
> Initializing both pointers of cpu_irqs[] to NULL is sufficient to shut
> up the compiler, even though they are definitely assigned in
> openrisc_sim_init() prior to the inlined call to
> openrisc_sim_ompic_init() containing the line in question.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>  hw/openrisc/openrisc_sim.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
> index d08ce6181199..95011a8015b4 100644
> --- a/hw/openrisc/openrisc_sim.c
> +++ b/hw/openrisc/openrisc_sim.c
> @@ -129,7 +129,7 @@ static void openrisc_sim_init(MachineState *machine)
>      const char *kernel_filename = machine->kernel_filename;
>      OpenRISCCPU *cpu = NULL;
>      MemoryRegion *ram;
> -    qemu_irq *cpu_irqs[2];
> +    qemu_irq *cpu_irqs[2] = {};

Ah I now remembered why this warning sound familiar:
https://bugs.launchpad.net/qemu/+bug/1874073

Peter suggested a different fix, I tested it, and was expecting Martin
Liska to post an updated patch.

>      qemu_irq serial_irq;
>      int n;
>      unsigned int smp_cpus = machine->smp.cpus;
>

-- 
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https://bugs.launchpad.net/bugs/1874073

Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  New

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

To manage notifications about this bug go to:
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Re: [PATCH] or1k: Fix compilation hiccup

[Christophe de Dinechin]

On 2020-05-26 at 20:51 CEST, Eric Blake wrote...
> On my Fedora 32 machine, gcc 10.1.1 at -O2 (the default for a bare
> './configure') has a false-positive complaint:
>
>   CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
> /home/eblake/qemu/hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
> /home/eblake/qemu/hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>    87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
>       |                                  ~~~~~~~~^~~
>
> Initializing both pointers of cpu_irqs[] to NULL is sufficient to shut
> up the compiler, even though they are definitely assigned in
> openrisc_sim_init() prior to the inlined call to
> openrisc_sim_ompic_init() containing the line in question.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>  hw/openrisc/openrisc_sim.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
> index d08ce6181199..95011a8015b4 100644
> --- a/hw/openrisc/openrisc_sim.c
> +++ b/hw/openrisc/openrisc_sim.c
> @@ -129,7 +129,7 @@ static void openrisc_sim_init(MachineState *machine)
>      const char *kernel_filename = machine->kernel_filename;
>      OpenRISCCPU *cpu = NULL;
>      MemoryRegion *ram;
> -    qemu_irq *cpu_irqs[2];
> +    qemu_irq *cpu_irqs[2] = {};

Why is the value [2] correct here? The loop that initializes loops over
machine->smp.cpus. Is it always less than 2 on this machine?


>      qemu_irq serial_irq;
>      int n;
>      unsigned int smp_cpus = machine->smp.cpus;


--
Cheers,
Christophe de Dinechin (IRC c3d)

Re: [PATCH] or1k: Fix compilation hiccup

[Peter Maydell]

On Fri, 29 May 2020 at 17:23, Christophe de Dinechin
<dinechin@redhat.com> wrote:
> On 2020-05-26 at 20:51 CEST, Eric Blake wrote...
> > diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
> > index d08ce6181199..95011a8015b4 100644
> > --- a/hw/openrisc/openrisc_sim.c
> > +++ b/hw/openrisc/openrisc_sim.c
> > @@ -129,7 +129,7 @@ static void openrisc_sim_init(MachineState *machine)
> >      const char *kernel_filename = machine->kernel_filename;
> >      OpenRISCCPU *cpu = NULL;
> >      MemoryRegion *ram;
> > -    qemu_irq *cpu_irqs[2];
> > +    qemu_irq *cpu_irqs[2] = {};
>
> Why is the value [2] correct here? The loop that initializes loops over
> machine->smp.cpus. Is it always less than 2 on this machine?

Yes: openrisc_sim_machine_init() sets mc->max_cpus = 2.
My suggestion of adding an assert() is essentially telling the
compiler that indeed smp_cpus must always be in the range [1,2],
which we can tell but it can't.

thanks
-- PMM

Re: [PATCH] or1k: Fix compilation hiccup

[Markus Armbruster]

Peter Maydell <peter.maydell@linaro.org> writes:

> On Fri, 29 May 2020 at 17:23, Christophe de Dinechin
> <dinechin@redhat.com> wrote:
>> On 2020-05-26 at 20:51 CEST, Eric Blake wrote...
>> > diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
>> > index d08ce6181199..95011a8015b4 100644
>> > --- a/hw/openrisc/openrisc_sim.c
>> > +++ b/hw/openrisc/openrisc_sim.c
>> > @@ -129,7 +129,7 @@ static void openrisc_sim_init(MachineState *machine)
>> >      const char *kernel_filename = machine->kernel_filename;
>> >      OpenRISCCPU *cpu = NULL;
>> >      MemoryRegion *ram;
>> > -    qemu_irq *cpu_irqs[2];
>> > +    qemu_irq *cpu_irqs[2] = {};
>>
>> Why is the value [2] correct here? The loop that initializes loops over
>> machine->smp.cpus. Is it always less than 2 on this machine?
>
> Yes: openrisc_sim_machine_init() sets mc->max_cpus = 2.
> My suggestion of adding an assert() is essentially telling the
> compiler that indeed smp_cpus must always be in the range [1,2],
> which we can tell but it can't.

Do we have a proper patch for this on the list?

Re: [PATCH] or1k: Fix compilation hiccup

[Markus Armbruster]

Markus Armbruster <armbru@redhat.com> writes:

> Peter Maydell <peter.maydell@linaro.org> writes:
>
>> On Fri, 29 May 2020 at 17:23, Christophe de Dinechin
>> <dinechin@redhat.com> wrote:
>>> On 2020-05-26 at 20:51 CEST, Eric Blake wrote...
>>> > diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
>>> > index d08ce6181199..95011a8015b4 100644
>>> > --- a/hw/openrisc/openrisc_sim.c
>>> > +++ b/hw/openrisc/openrisc_sim.c
>>> > @@ -129,7 +129,7 @@ static void openrisc_sim_init(MachineState *machine)
>>> >      const char *kernel_filename = machine->kernel_filename;
>>> >      OpenRISCCPU *cpu = NULL;
>>> >      MemoryRegion *ram;
>>> > -    qemu_irq *cpu_irqs[2];
>>> > +    qemu_irq *cpu_irqs[2] = {};
>>>
>>> Why is the value [2] correct here? The loop that initializes loops over
>>> machine->smp.cpus. Is it always less than 2 on this machine?
>>
>> Yes: openrisc_sim_machine_init() sets mc->max_cpus = 2.
>> My suggestion of adding an assert() is essentially telling the
>> compiler that indeed smp_cpus must always be in the range [1,2],
>> which we can tell but it can't.
>
> Do we have a proper patch for this on the list?

Apparently not.

Philippe did try Peter's suggestion, found it works, but then posted it
only to Launchpad.  Philippe, please post to the list, so we can finally
get this fixed.

Re: [PATCH] or1k: Fix compilation hiccup

[Philippe Mathieu-Daudé]

On 6/8/20 8:03 AM, Markus Armbruster wrote:
> Markus Armbruster <armbru@redhat.com> writes:
> 
>> Peter Maydell <peter.maydell@linaro.org> writes:
>>
>>> On Fri, 29 May 2020 at 17:23, Christophe de Dinechin
>>> <dinechin@redhat.com> wrote:
>>>> On 2020-05-26 at 20:51 CEST, Eric Blake wrote...
>>>>> diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
>>>>> index d08ce6181199..95011a8015b4 100644
>>>>> --- a/hw/openrisc/openrisc_sim.c
>>>>> +++ b/hw/openrisc/openrisc_sim.c
>>>>> @@ -129,7 +129,7 @@ static void openrisc_sim_init(MachineState *machine)
>>>>>      const char *kernel_filename = machine->kernel_filename;
>>>>>      OpenRISCCPU *cpu = NULL;
>>>>>      MemoryRegion *ram;
>>>>> -    qemu_irq *cpu_irqs[2];
>>>>> +    qemu_irq *cpu_irqs[2] = {};
>>>>
>>>> Why is the value [2] correct here? The loop that initializes loops over
>>>> machine->smp.cpus. Is it always less than 2 on this machine?
>>>
>>> Yes: openrisc_sim_machine_init() sets mc->max_cpus = 2.
>>> My suggestion of adding an assert() is essentially telling the
>>> compiler that indeed smp_cpus must always be in the range [1,2],
>>> which we can tell but it can't.
>>
>> Do we have a proper patch for this on the list?
> 
> Apparently not.
> 
> Philippe did try Peter's suggestion, found it works, but then posted it
> only to Launchpad.  Philippe, please post to the list, so we can finally
> get this fixed.

Sorry since it was Eric finding, I didn't understood I had to post it.
Will do.

Re: [PATCH] or1k: Fix compilation hiccup

[Markus Armbruster]

Philippe Mathieu-Daudé <philmd@redhat.com> writes:

> On 6/8/20 8:03 AM, Markus Armbruster wrote:
>> Markus Armbruster <armbru@redhat.com> writes:
>> 
>>> Peter Maydell <peter.maydell@linaro.org> writes:
>>>
>>>> On Fri, 29 May 2020 at 17:23, Christophe de Dinechin
>>>> <dinechin@redhat.com> wrote:
>>>>> On 2020-05-26 at 20:51 CEST, Eric Blake wrote...
>>>>>> diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
>>>>>> index d08ce6181199..95011a8015b4 100644
>>>>>> --- a/hw/openrisc/openrisc_sim.c
>>>>>> +++ b/hw/openrisc/openrisc_sim.c
>>>>>> @@ -129,7 +129,7 @@ static void openrisc_sim_init(MachineState *machine)
>>>>>>      const char *kernel_filename = machine->kernel_filename;
>>>>>>      OpenRISCCPU *cpu = NULL;
>>>>>>      MemoryRegion *ram;
>>>>>> -    qemu_irq *cpu_irqs[2];
>>>>>> +    qemu_irq *cpu_irqs[2] = {};
>>>>>
>>>>> Why is the value [2] correct here? The loop that initializes loops over
>>>>> machine->smp.cpus. Is it always less than 2 on this machine?
>>>>
>>>> Yes: openrisc_sim_machine_init() sets mc->max_cpus = 2.
>>>> My suggestion of adding an assert() is essentially telling the
>>>> compiler that indeed smp_cpus must always be in the range [1,2],
>>>> which we can tell but it can't.
>>>
>>> Do we have a proper patch for this on the list?
>> 
>> Apparently not.
>> 
>> Philippe did try Peter's suggestion, found it works, but then posted it
>> only to Launchpad.  Philippe, please post to the list, so we can finally
>> get this fixed.
>
> Sorry since it was Eric finding, I didn't understood I had to post it.
> Will do.

You didn't *have* to, but it'll help if you do :)

Re: [PATCH] or1k: Fix compilation hiccup

[Eric Blake]

On 6/8/20 4:15 AM, Markus Armbruster wrote:

>>>>> Yes: openrisc_sim_machine_init() sets mc->max_cpus = 2.
>>>>> My suggestion of adding an assert() is essentially telling the
>>>>> compiler that indeed smp_cpus must always be in the range [1,2],
>>>>> which we can tell but it can't.
>>>>
>>>> Do we have a proper patch for this on the list?
>>>
>>> Apparently not.
>>>
>>> Philippe did try Peter's suggestion, found it works, but then posted it
>>> only to Launchpad.  Philippe, please post to the list, so we can finally
>>> get this fixed.
>>
>> Sorry since it was Eric finding, I didn't understood I had to post it.
>> Will do.
> 
> You didn't *have* to, but it'll help if you do :)

Now at https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg01779.html

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

[Bug 1874073] [NEW] openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized in this function [-Werror=maybe-uninitialized]

[Martin Liska]

Public bug reported:

I see the warning since gcc10:

static void openrisc_sim_init(MachineState *machine):
...
    qemu_irq *cpu_irqs[2];
...


    serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                   115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

I would initialize cpu_irqs[2] with {}.

** Affects: qemu
     Importance: Undecided
         Status: New

-- 
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Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  New

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

To manage notifications about this bug go to:
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[Bug 1874073] Re: openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized in this function [-Werror=maybe-uninitialized]

[Martin Liska]

Suggested patch:

diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
index 79e7049..724dcd0 100644
--- a/hw/openrisc/openrisc_sim.c
+++ b/hw/openrisc/openrisc_sim.c
@@ -129,7 +129,7 @@ static void openrisc_sim_init(MachineState *machine)
     const char *kernel_filename = machine->kernel_filename;
     OpenRISCCPU *cpu = NULL;
     MemoryRegion *ram;
-    qemu_irq *cpu_irqs[2];
+    qemu_irq *cpu_irqs[2] = {};
     qemu_irq serial_irq;
     int n;
     unsigned int smp_cpus = machine->smp.cpus;

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Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  New

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

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[Bug 1874073] Re: openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized in this function [-Werror=maybe-uninitialized]

[Peter Maydell]

I'm not sure why the compiler thinks it might be uninitialized here --
is it just that it's not aware that smp_cpus can't be zero and so the
loop will always initialize cpu_irqs[0] ?

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Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  New

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

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[Bug 1874073] Re: openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized in this function [-Werror=maybe-uninitialized]

[Martin Liska]

Note that our -Wmaybe-uninitialized warnings tends to report false positives. We have a rich meta bug for it:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=24639

That's why it can't prove the variable is initialized in all possible
execution paths.

** Bug watch added: GCC Bugzilla #24639
   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=24639

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Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  New

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

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[Bug 1874073] Re: openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized in this function [-Werror=maybe-uninitialized]

[Peter Maydell]

Does adding "assert(smp_cpus >= 1 && smp_cpus <= 2);" after the
assignment to smp_cpus give the compiler enough information to know
there's no use of uninitialized data?

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Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  New

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

To manage notifications about this bug go to:
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[Bug 1874073] Re: openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized in this function [-Werror=maybe-uninitialized]

[Philippe Mathieu-Daudé]

Confirming Peter's suggestion does silent the warning.

-- >8 --
diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
index d08ce61811..02f5259e5e 100644
--- a/hw/openrisc/openrisc_sim.c
+++ b/hw/openrisc/openrisc_sim.c
@@ -134,6 +134,7 @@ static void openrisc_sim_init(MachineState *machine)
     int n;
     unsigned int smp_cpus = machine->smp.cpus;
 
+    assert(smp_cpus >= 1 && smp_cpus <= 2);
     for (n = 0; n < smp_cpus; n++) {
         cpu = OPENRISC_CPU(cpu_create(machine->cpu_type));
         if (cpu == NULL) {
---

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Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  New

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

To manage notifications about this bug go to:
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[Bug 1874073] Re: openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized in this function [-Werror=maybe-uninitialized]

[Martin Liska]

Hello. The assert approach is preferred.

-- 
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Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  New

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

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[Bug 1874073] Re: openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized in this function [-Werror=maybe-uninitialized]

[Philippe Mathieu-Daudé]

** Changed in: qemu
       Status: New => Confirmed

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Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  Confirmed

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

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[PATCH v2] hw/openrisc/openrisc_sim: Add assertion to silence GCC warning

[Philippe Mathieu-Daudé]

When compiling with GCC 10 (Fedora 32) using CFLAGS=-O2 we get:

    CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
  hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
  hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
     87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
        |                                  ~~~~~~~~^~~

While humans can tell smp_cpus will always be in the [1, 2] range,
(openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
can't.

Add an assertion to give the compiler a hint there's no use of
uninitialized data.

Buglink: https://bugs.launchpad.net/qemu/+bug/1874073
Reported-by: Martin Liška <mliska@suse.cz>
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
v2: Fixed typo in subject (eblake)
Supersedes: <20200608071409.17024-1-philmd@redhat.com>
---
 hw/openrisc/openrisc_sim.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
index d08ce61811..02f5259e5e 100644
--- a/hw/openrisc/openrisc_sim.c
+++ b/hw/openrisc/openrisc_sim.c
@@ -134,6 +134,7 @@ static void openrisc_sim_init(MachineState *machine)
     int n;
     unsigned int smp_cpus = machine->smp.cpus;
 
+    assert(smp_cpus >= 1 && smp_cpus <= 2);
     for (n = 0; n < smp_cpus; n++) {
         cpu = OPENRISC_CPU(cpu_create(machine->cpu_type));
         if (cpu == NULL) {
-- 
2.21.3

[Bug 1874073] [PATCH v2] hw/openrisc/openrisc_sim: Add assertion to silence GCC warning

[Philippe Mathieu-Daudé]

When compiling with GCC 10 (Fedora 32) using CFLAGS=-O2 we get:

    CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
  hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
  hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
     87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
        |                                  ~~~~~~~~^~~

While humans can tell smp_cpus will always be in the [1, 2] range,
(openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
can't.

Add an assertion to give the compiler a hint there's no use of
uninitialized data.

Buglink: https://bugs.launchpad.net/qemu/+bug/1874073
Reported-by: Martin Liška <mliska@suse.cz>
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
v2: Fixed typo in subject (eblake)
Supersedes: <20200608071409.17024-1-philmd@redhat.com>
---
 hw/openrisc/openrisc_sim.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
index d08ce61811..02f5259e5e 100644
--- a/hw/openrisc/openrisc_sim.c
+++ b/hw/openrisc/openrisc_sim.c
@@ -134,6 +134,7 @@ static void openrisc_sim_init(MachineState *machine)
     int n;
     unsigned int smp_cpus = machine->smp.cpus;
 
+    assert(smp_cpus >= 1 && smp_cpus <= 2);
     for (n = 0; n < smp_cpus; n++) {
         cpu = OPENRISC_CPU(cpu_create(machine->cpu_type));
         if (cpu == NULL) {
-- 
2.21.3

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https://bugs.launchpad.net/bugs/1874073

Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  Confirmed

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

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Re: [PATCH v2] hw/openrisc/openrisc_sim: Add assertion to silence GCC warning

[Richard Henderson]

On 6/8/20 9:06 AM, Philippe Mathieu-Daudé wrote:
> When compiling with GCC 10 (Fedora 32) using CFLAGS=-O2 we get:
> 
>     CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
>   hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
>   hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>      87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
>         |                                  ~~~~~~~~^~~
> 
> While humans can tell smp_cpus will always be in the [1, 2] range,
> (openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
> can't.
> 
> Add an assertion to give the compiler a hint there's no use of
> uninitialized data.
> 
> Buglink: https://bugs.launchpad.net/qemu/+bug/1874073
> Reported-by: Martin Liška <mliska@suse.cz>
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> Tested-by: Eric Blake <eblake@redhat.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> v2: Fixed typo in subject (eblake)
> Supersedes: <20200608071409.17024-1-philmd@redhat.com>
> ---
>  hw/openrisc/openrisc_sim.c | 1 +
>  1 file changed, 1 insertion(+)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

[Bug 1874073] Re: [PATCH v2] hw/openrisc/openrisc_sim: Add assertion to silence GCC warning

[Laurent Vivier]

Le 08/06/2020 à 18:06, Philippe Mathieu-Daudé a écrit :
> When compiling with GCC 10 (Fedora 32) using CFLAGS=-O2 we get:
> 
>     CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
>   hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
>   hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>      87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
>         |                                  ~~~~~~~~^~~
> 
> While humans can tell smp_cpus will always be in the [1, 2] range,
> (openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
> can't.
> 
> Add an assertion to give the compiler a hint there's no use of
> uninitialized data.
> 
> Buglink: https://bugs.launchpad.net/qemu/+bug/1874073
> Reported-by: Martin Liška <mliska@suse.cz>
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> Tested-by: Eric Blake <eblake@redhat.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> v2: Fixed typo in subject (eblake)
> Supersedes: <20200608071409.17024-1-philmd@redhat.com>
> ---
>  hw/openrisc/openrisc_sim.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
> index d08ce61811..02f5259e5e 100644
> --- a/hw/openrisc/openrisc_sim.c
> +++ b/hw/openrisc/openrisc_sim.c
> @@ -134,6 +134,7 @@ static void openrisc_sim_init(MachineState *machine)
>      int n;
>      unsigned int smp_cpus = machine->smp.cpus;
>  
> +    assert(smp_cpus >= 1 && smp_cpus <= 2);
>      for (n = 0; n < smp_cpus; n++) {
>          cpu = OPENRISC_CPU(cpu_create(machine->cpu_type));
>          if (cpu == NULL) {
> 

Applied to my trivial-patches branch.

Thanks,
Laurent

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1874073

Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  Confirmed

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1874073/+subscriptions

Re: [PATCH v2] hw/openrisc/openrisc_sim: Add assertion to silence GCC warning

[Laurent Vivier]

Le 08/06/2020 à 18:06, Philippe Mathieu-Daudé a écrit :
> When compiling with GCC 10 (Fedora 32) using CFLAGS=-O2 we get:
> 
>     CC      or1k-softmmu/hw/openrisc/openrisc_sim.o
>   hw/openrisc/openrisc_sim.c: In function ‘openrisc_sim_init’:
>   hw/openrisc/openrisc_sim.c:87:42: error: ‘cpu_irqs[0]’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>      87 |         sysbus_connect_irq(s, i, cpu_irqs[i][irq_pin]);
>         |                                  ~~~~~~~~^~~
> 
> While humans can tell smp_cpus will always be in the [1, 2] range,
> (openrisc_sim_machine_init sets mc->max_cpus = 2), the compiler
> can't.
> 
> Add an assertion to give the compiler a hint there's no use of
> uninitialized data.
> 
> Buglink: https://bugs.launchpad.net/qemu/+bug/1874073
> Reported-by: Martin Liška <mliska@suse.cz>
> Suggested-by: Peter Maydell <peter.maydell@linaro.org>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> Tested-by: Eric Blake <eblake@redhat.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> v2: Fixed typo in subject (eblake)
> Supersedes: <20200608071409.17024-1-philmd@redhat.com>
> ---
>  hw/openrisc/openrisc_sim.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
> index d08ce61811..02f5259e5e 100644
> --- a/hw/openrisc/openrisc_sim.c
> +++ b/hw/openrisc/openrisc_sim.c
> @@ -134,6 +134,7 @@ static void openrisc_sim_init(MachineState *machine)
>      int n;
>      unsigned int smp_cpus = machine->smp.cpus;
>  
> +    assert(smp_cpus >= 1 && smp_cpus <= 2);
>      for (n = 0; n < smp_cpus; n++) {
>          cpu = OPENRISC_CPU(cpu_create(machine->cpu_type));
>          if (cpu == NULL) {
> 

Applied to my trivial-patches branch.

Thanks,
Laurent

[Bug 1874073] Re: openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized in this function [-Werror=maybe-uninitialized]

[Philippe Mathieu-Daudé]

Merged in commit 1db889c71f37d5bad411b2ef83a69739d9d598f9.

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

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https://bugs.launchpad.net/bugs/1874073

Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  Fix Committed

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

To manage notifications about this bug go to:
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[Bug 1874073] Re: openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized in this function [-Werror=maybe-uninitialized]

[Thomas Huth]

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

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https://bugs.launchpad.net/bugs/1874073

Title:
  openrisc_sim.c:87:42: error: 'cpu_irqs[0]' may be used uninitialized
  in this function [-Werror=maybe-uninitialized]

Status in QEMU:
  Fix Released

Bug description:
  I see the warning since gcc10:

  static void openrisc_sim_init(MachineState *machine):
  ...
      qemu_irq *cpu_irqs[2];
  ...

  
      serial_mm_init(get_system_memory(), 0x90000000, 0, serial_irq,
                     115200, serial_hd(0), DEVICE_NATIVE_ENDIAN);

  I would initialize cpu_irqs[2] with {}.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1874073/+subscriptions