[Bug target/57907] New: warning: switch -mcpu=cortex-a15 conflicts with -march=armv7-a switch [enabled by default]

[Bug target/57907] New: warning: switch -mcpu=cortex-a15 conflicts with -march=armv7-a switch [enabled by default]

[christian.helmuth@genode-labs.com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57907

            Bug ID: 57907
           Summary: warning: switch -mcpu=cortex-a15 conflicts with
                    -march=armv7-a switch [enabled by default]
           Product: gcc
           Version: 4.7.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: christian.helmuth@genode-labs.com

The manpage states that "This option [-march] can be used in conjunction with
or instead of the -mcpu= option." and this works for, e.g., -mcpu=cortex-a9. On
the other GCC complains for -mcpu=cortex-a15 and -mcpu=cortex-a7 in conjunction
with -march=armv7-a.

The following command line reproduces the issue:

> echo "int main() {}" | /usr/local/genode-gcc/bin/genode-arm-g++ -c -x c++ - -o /tmp/stdin.o -march=armv7-a -mcpu=cortex-a15
<stdin>:1:0: warning: switch -mcpu=cortex-a15 conflicts with -march=armv7-a
switch [enabled by default]

Examples in bugzilla never user both options for ARM but just -mcpu. Will the
combination be supported in the future or should I adapt the mcpu-only
approach? Does it have drawbacks?

[Bug target/57907] warning: switch -mcpu=cortex-a15 conflicts with -march=armv7-a switch [enabled by default]

[rearnsha at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57907

--- Comment #1 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
You get the warning because Cortex-A15 implements a superset of ARM-v7a, due to
the addition of the HW division instructions.  This means that -march=armv7-a
and -mcpu=cortex-a15 leads to an ambiguity as to what architectural features
you want and hence the warning.

It's not currently possible to specify the exact architecture variant that A15
supports in the command line; we're looking at fixing that in future.

[Bug target/57907] warning: switch -mcpu=cortex-a15 conflicts with -march=armv7-a switch [enabled by default]

[ramana at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57907

Ramana Radhakrishnan <ramana at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-08-14
                 CC|                            |ramana at gcc dot gnu.org
     Ever confirmed|0                           |1

[Bug target/57907] warning: switch -mcpu=cortex-a15 conflicts with -march=armv7-a switch [enabled by default]

[alexander.stohr at gmx dot de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57907

Alexander Stohr <alexander.stohr at gmx dot de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |alexander.stohr at gmx dot de

--- Comment #2 from Alexander Stohr <alexander.stohr at gmx dot de> ---
Cortex-A15 is getting pretty widespread with even a speed up / follow up /
revised variant popping up from the chip vendors.
having no matching command set profile for that core should not be the long
term state.
ticking this report now in the hope it can be resolved in a near future now.

[Bug target/57907] warning: switch -mcpu=cortex-a15 conflicts with -march=armv7-a switch [enabled by default]

[ramana at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57907

Ramana Radhakrishnan <ramana at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.9.0

--- Comment #3 from Ramana Radhakrishnan <ramana at gcc dot gnu.org> ---
This is now fixed. 

With the commit for v7ve http://gcc.gnu.org/ml/gcc-cvs/2014-01/msg00982.html

Ramana

[Bug target/57907] warning: switch -mcpu=cortex-a15 conflicts with -march=armv7-a switch [enabled by default]

[ramana at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57907

Ramana Radhakrishnan <ramana at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #4 from Ramana Radhakrishnan <ramana at gcc dot gnu.org> ---
fixed.