[Bug web/62211] New: ./configure --with-float= and ARM

["dilyan.palauzov at aegee dot org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62211

            Bug ID: 62211
           Summary: ./configure --with-float= and ARM
           Product: gcc
           Version: 4.9.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: web
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dilyan.palauzov at aegee dot org

At https://gcc.gnu.org/install/configure.html is written:

Options specification

--with-fpu=type
--with-float=type
  These configure options provide default values for the -mfpu= option and for
-mhard-float or -msoft-float.

I want to configure for ARM.  In the gcc manual, node 3.1 Option Summary under
_ARM Options_ is mentioned the option -mfloat-abi= but -m(hard,sort)-float are
not mentioned.

In node 3.17.4 ARM Options is mentioned, that -mfloat-abi can be hard, soft or
softfp.

Does ./configure-ing gcc --with-float=X lead to defaulting the -mfloat-abi
option later, when gcc is not called?  In such a case, the documentation for
configuring gcc shall mention, that --with-float=type on ARM has no impact on
-msoft-float or -mhard-float, but on -mfloat-abi .

The documentation of GCC does mention neither -mhard-float nor -msoft-float as
general options nor as ARM-specific options, so I conclude that these are not
permitted.

However, the documentation of -mfpu= , where the ARM options are described,
mentions:

     If '-msoft-float' is specified this specifies the format of floating-point
values.


So apparently, -msoft-float can be passed, when gcc produces ARM-code.

Please clarify in the gcc manual if -msoft-float is the same as
-mfloat-abi=soft, if -mhard-float is the same as -mfloat-abi=hard and if these,
including -mfloag-abu=softfp are impacted by ./configure --with-float .