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From: "michael.hope at linaro dot org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c/48783] New: ARM: kernel compiled at -O2 has a unused reference to __aeabi_uldivmod
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48783

           Summary: ARM: kernel compiled at -O2 has a unused reference to
                    __aeabi_uldivmod
           Product: gcc
           Version: 4.5.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: michael.hope@linaro.org


Created attachment 24107
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24107
Preprocessed source

When compiled, the attached code refers to the 64 bit unsigned divmod helper
function '__aeabi_uldivmod' even though the function is never called.  This
causes a link error when cross-compiling an ARM Linux 2.6.38 kernel.

To reproduce:
 * Make a arm-linux-gnueabi cross compiler configured with --with-mode=thumb
--with-arch=armv7-a --with-tune=cortex-a9 --with-float=softfp --with-fpu=neon
 * Compile the attached code with 'arm-linux-gnueabi-gcc -O2 -S wm8974.i'
 * See a '.global __aeabi_uldivmod' in the header of wm8974_set_dai_pll

Marking pll_factors() as noinline or putting asm("" : "+r"(source)); before the
call to do_div() works around the problem.