[Bug target/54461] New: [avr] add configure option for better AVR-Libc integration

[Bug target/54461] New: [avr] add configure option for better AVR-Libc integration

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54461

             Bug #: 54461
           Summary: [avr] add configure option for better AVR-Libc
                    integration
    Classification: Unclassified
           Product: gcc
           Version: 4.7.1
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: gjl@gcc.gnu.org
        ReportedBy: gjl@gcc.gnu.org
            Target: avr


For historical reasons, AVR-Libc implements functions that GCC expects to live
in libgcc, namely float functions like __fixsfsi.

Currently, avr-gcc is not configurable to accommodate that situation which
leads to performance loss if the float support functions from libgcc are used.

This happens at least in the following situations:

* The user does not specify -lm.  -lm should only be needed
  if function from math.h are used, not for language core
  features like int i = (int) float.

* The application is LTO compiled, i.e. linked with -flto.
  The plugin machinery passes lgcc -lc lgcc through to the
  linker by means of -plugin-opt=-pass-through=-lgcc etc.
  so that -lgcc is linked prior to -lm.

* The user uses fixed <-> float conversion routines from
  libgcc.  These routines refer float functions, and the linker
  resolves these function in libgcc if they are there.

* avr-g++ is used as linker driver.

See also PR28718 and
http://lists.gnu.org/archive/html/avr-gcc-list/2012-08/msg00070.html

[Bug target/54461] [avr] add configure option for better AVR-Libc integration

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54461

Georg-Johann Lay <gjl at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P4
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-09-02
                 CC|                            |eric.weddington at atmel
                   |                            |dot com
   Target Milestone|---                         |4.7.2
     Ever Confirmed|0                           |1
           Severity|normal                      |enhancement

[Bug target/54461] [avr] add configure option for better AVR-Libc integration

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54461

--- Comment #1 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2012-09-05 08:48:00 UTC ---
Author: gjl
Date: Wed Sep  5 08:47:50 2012
New Revision: 190967

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=190967
Log:
    PR target/54461
    * configure.ac (noconfigdirs,target=avr-*-*): Add target-newlib,
    target-libgloss if not configured --with-avrlibc=no.
    * configure: Regenerate.

libgcc/
    PR target/54461
    * config.host (tmake_file,host=avr-*-*): Add avr/t-avrlibc if
    not configured --with-avrlibc=no.
    * config/avr/t-avrlibc: New file.
    * Makefile.in (FPBIT_FUNCS): filter-out LIB2FUNCS_EXCLUDE.
    (DPBIT_FUNCS): Ditto.
    (TPBIT_FUNCS): Ditto.

gcc/
    PR target/54461
    * config.gcc (tm_file,target=avr-*-*): Add avr/avrlibc.h if
    not configured --with-avrlibc=no.
    (tm_defines,target=avr-*-*): Add WITH_AVRLIBC if not configured
    --with-avrlibc=no.
    * config/avr/avrlibc.h: New file.
    * config/avr/avr-c.c: Build-in define __WITH_AVRLIBC__ if
    not configured --with-avrlibc=no.
    * doc/invoke.texi (AVR Built-in Macros): Document __WITH_AVRLIBC__


Added:
    trunk/gcc/config/avr/avrlibc.h
    trunk/libgcc/config/avr/t-avrlibc
Modified:
    trunk/ChangeLog
    trunk/configure
    trunk/configure.ac
    trunk/gcc/ChangeLog
    trunk/gcc/config.gcc
    trunk/gcc/config/avr/avr-c.c
    trunk/gcc/doc/invoke.texi
    trunk/libgcc/ChangeLog
    trunk/libgcc/Makefile.in
    trunk/libgcc/config.host

[Bug target/54461] [avr] add configure option for better AVR-Libc integration

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54461

--- Comment #2 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2012-09-05 12:19:54 UTC ---
Author: gjl
Date: Wed Sep  5 12:19:47 2012
New Revision: 190973

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=190973
Log:
    Backport from 2012-09-05 mainline r190697.

    PR target/54461
    * configure.ac (noconfigdirs,target=avr-*-*): Add target-newlib,
    target-libgloss if configured --with-avrlibc.
    * configure: Regenerate.

libgcc/
    Backport from 2012-09-05 mainline r190697.

    PR target/54461
    * config.host (tmake_file,host=avr-*-*): Add avr/t-avrlibc if
    configured --with-avrlibc.
    * Makefile.in (FPBIT_FUNCS): filter-out LIB2FUNCS_EXCLUDE.
    (DPBIT_FUNCS): Ditto.
    (TPBIT_FUNCS): Ditto.
    * config/avr/t-avrlibc: New file.

gcc/
    Backport from 2012-09-05 mainline r190697.

    PR target/54461
    * config.gcc (tm_file,target=avr-*-*): Add avr/avrlibc.h if
    configured --with-avrlibc.
    (tm_defines,target=avr-*-*): Add WITH_AVRLIBC if configured
    --with-avrlibc.
    * config/avr/avrlibc.h: New file.
    * config/avr/avr-c.c: Build-in define __WITH_AVRLIBC__ if
    configured --with-avrlibc.
    * doc/invoke.texi (AVR Built-in Macros): Document __WITH_AVRLIBC__


Added:
    branches/gcc-4_7-branch/gcc/config/avr/avrlibc.h
    branches/gcc-4_7-branch/libgcc/config/avr/t-avrlibc
Modified:
    branches/gcc-4_7-branch/ChangeLog
    branches/gcc-4_7-branch/configure
    branches/gcc-4_7-branch/configure.ac
    branches/gcc-4_7-branch/gcc/ChangeLog
    branches/gcc-4_7-branch/gcc/config.gcc
    branches/gcc-4_7-branch/gcc/config/avr/avr-c.c
    branches/gcc-4_7-branch/gcc/doc/invoke.texi
    branches/gcc-4_7-branch/libgcc/ChangeLog
    branches/gcc-4_7-branch/libgcc/Makefile.in
    branches/gcc-4_7-branch/libgcc/config.host

[Bug target/54461] [avr] add configure option for better AVR-Libc integration

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54461

Georg-Johann Lay <gjl at gcc dot gnu.org> changed:

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

--- Comment #3 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2012-09-05 12:23:00 UTC ---
Fixed in 4.7.2

[Bug target/54461] [avr] add configure option for better AVR-Libc integration

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54461

Georg-Johann Lay <gjl at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |j at uriah dot heep.sax.de

--- Comment #4 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2012-09-05 13:02:24 UTC ---
*** Bug 28718 has been marked as a duplicate of this bug. ***

[Bug target/54461] [avr] add configure option for better AVR-Libc integration

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54461

--- Comment #5 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2013-01-07 16:23:13 UTC ---
Author: gjl
Date: Mon Jan  7 16:22:59 2013
New Revision: 194981

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=194981
Log:
    Backport from 2013-01-07 trunk r194978.
    PR target/54461
    * doc/install.texi (Cross-Compiler-Specific Options): Document
    --with-avrlibc.


Modified:
    branches/gcc-4_7-branch/gcc/ChangeLog
    branches/gcc-4_7-branch/gcc/doc/install.texi