Experimental Physics and
Industrial Control System

"Zimoch Dirk \(PSI\) via Core-talk" <core-talk at aps.anl.gov> · Thu, 4 Jun 2020 13:10:17 +0000

The problem seems to be that -fno-implicit-fp forbids to inline floating point functions into non-floating point
functions. In case of expire, the function uses no float/double explicitly:

epicsTimerNotify::expireStatus timerForOldFdmgr::expire ( const epicsTime & )
{
    (*this->pFunc) (this->pParam);
    return noRestart;
}

But epicsTimerNotify::expireStatus is a class containing a double. As the error happens at the closing } it probably
inlining the implicit operator= of the return value.

What I did now to solve the problem is to remove -fno-implicit-fp from ARCH_DEP_CFLAGS (which is used for C and C++) and
to add it to CODE_CFLAGS, which is used for C but not for C++. This is under the assumption that interrupt handlers are
written in C, not C++. But this does not cover extern "C" ISRs in C++.

Maybe using __attribute__((optimize ("-fno-implicit-fp"))) or #pragma GCC ("-fno-implicit-fp") would be a better choice
to treat ISRs, but unfortunately both are not understood by the VxWorks 6.9 compiler. At least it warns: "'optimize'
attribute directive ignored".

On Thu, 2020-06-04 at 09:24 +0000, Zimoch Dirk (PSI) via Core-talk wrote:
> It was on TechTalk in 2014 already: https://epics.anl.gov/tech-talk/2014/msg01579.php
> 
> On Thu, 2020-06-04 at 08:55 +0000, Zimoch Dirk (PSI) via Core-talk wrote:
> > I found that the option -fno-implicit-fp causes the problem. When adding it to the generic ppc32 configuration, I get
> > the same "unable to find a register to spill in class 'FLOAT_REGS'" error unless I add -fno-expensive-optimizations as
> > well.
> > 
> > I had originally added this option when I ran into strange run-time errors because an interrupt handler of some driver
> > had used floating point registers without being asked to do so for moving "long long" values. As the floating point
> > registers are not saved when entering interrupt mode, bad things happened to the interrupted thread.
> > 
> > 
> > On Wed, 2020-06-03 at 17:51 +0000, Johnson, Andrew N. wrote:
> > > I suspect that the CPU-specific code in gcc for the ppc604 target is older than for the ppc32 target and can’t cope with newer constructs, we’ve had similar issues before. That’s why I really want to encourage you try the ppc32 targets, I don’t think they will show these errors at all and switching will save you time investigating the problems.
> > > 
> > > - Andrew
> > > 
> > > On Jun 3, 2020, at 12:30 PM, Zimoch Dirk (PSI) via Core-talk <core-talk at aps.anl.gov> wrote:
> > > > 3 files have problems implementing the pure virtual function epicsTimerNotify::expire(): fdmgr.cc line 152, epicsTime.cpp line 62 and epicsTimerTest.cpp line 319. What helps is -O1 or -no-expensive-optimizations.
> > > > 
> > > > As I expect problems with any code that implements expire() I have now added 'CXXFLAGS += -fno-expensive-optimizations' to the general options for that architecture, not only for the 3 failing files.
> > > > 
> > > > This does not yet solve the problem with typeCast.h.
> > > > 
> > > > More tests tomorrow.
> > > > 
> > > > > -----Ursprüngliche Nachricht-----
> > > > > Von: Michael Davidsaver <mdavidsaver at gmail.com>
> > > > > Gesendet: Mittwoch, 3. Juni 2020 18:48
> > > > > An: Zimoch Dirk (PSI) <dirk.zimoch at psi.ch>; 'core-talk at aps.anl.gov' <core-
> > > > > talk at aps.anl.gov>
> > > > > Betreff: Re: AW: EPICS 7 and VxWorks 6.9 for PPC604?
> > > > > 
> > > > > On 6/3/20 8:31 AM, Zimoch Dirk (PSI) wrote:
> > > > > > I will try the selective -fno-inline ...
> > > > > 
> > > > >  
> > > > > If vxworks 6.7 had gcc 4.1 then the threshold for using
> > > > > __attribute__((always_inline)) is now being crossed.
> > > > > 
> > > > > https://github.com/epics-
> > > > > base/pvDataCPP/blob/0fa927afa7d92f490f92eb4906e27046080309e2/src/misc
> > > > > /pv/templateMeta.h#L15-L16
> > > > > 
> > > > > > > -----Ursprüngliche Nachricht-----
> > > > > > > Von: Zimoch Dirk (PSI)
> > > > > > > Gesendet: Mittwoch, 3. Juni 2020 17:30
> > > > > > > An: 'Michael Davidsaver' <mdavidsaver at gmail.com>; 'core-
> > > > > 
> > > > >  talk at aps.anl.gov'
> > > > > > > <core-talk at aps.anl.gov>
> > > > > > > Betreff: AW: EPICS 7 and VxWorks 6.9 for PPC604?
> > > > > > > 
> > > > > > > It's gcc 4.3.3.
> > > > > > > 
> > > > > > > Using -O0 (as used to fix bug 1702298) in helps for fdmgr.cpp but not for
> > > > > > > typeCast.h.
> > > > > > > 
> > > > > > > > -----Ursprüngliche Nachricht-----
> > > > > > > > Von: Michael Davidsaver <mdavidsaver at gmail.com>
> > > > > > > > Gesendet: Mittwoch, 3. Juni 2020 17:13
> > > > > > > > An: Zimoch Dirk (PSI) <dirk.zimoch at psi.ch>; 'core-talk at aps.anl.gov' <core-
> > > > > > > > talk at aps.anl.gov>
> > > > > > > > Betreff: Re: EPICS 7 and VxWorks 6.9 for PPC604?
> > > > > > > > 
> > > > > > > > For those of us who aren't so familiar with vxworks, which GCC version(s)
> > > > > 
> > > > >  are
> > > > > > > > involved.
> > > > > > > > 
> > > > > > > > You may remember https://bugs.launchpad.net/epics-base/+bug/1702298
> > > > > > > > 
> > > > > > > > 
> > > > > > > > On 6/3/20 8:04 AM, Zimoch Dirk (PSI) via Core-talk wrote:
> > > > > > > > > Has anyone already compiled EPICS 7 for VxWorks 6.9 for PPC604?
> > > > > > > > > I have problems:
> > > > > > > > > 
> > > > > > > > > With -O2 it fails here:
> > > > > > > > > 
> > > > > > > > > ../fdmgr/fdmgr.cpp: In member function 'virtual
> > > > > > > > 
> > > > > > > >  epicsTimerNotify::expireStatus timerForOldFdmgr::expire(const
> > > > > 
> > > > >  epicsTime&)':
> > > > > > > > > ../fdmgr/fdmgr.cpp:152: error: unable to find a register to spill in class
> > > > > > > > 
> > > > > > > >  'FLOAT_REGS'
> > > > > > > > > ../fdmgr/fdmgr.cpp:152: error: this is the insn:
> > > > > > > > > (insn:HI 16 15 17 2 ../fdmgr/fdmgr.cpp:151 (set (reg:DF 126 [
> > > > > 
> > > > >  D.11913.delay
> > > > > > > ])
> > > > > > > > >        (mem/s/j/c:DF (plus:SI (reg/f:SI 113 sfp)
> > > > > > > > >                (const_int 8 [0x8])) [0 D.11913.delay+0 S8 A64])) 336
> > > > > > > > 
> > > > > > > >  {*movdf_hardfloat32} (expr_list:REG_EQUIV (mem/s/j/c:DF (plus:SI (reg/f:SI
> > > > > > > 
> > > > > > >  113
> > > > > > > > sfp)
> > > > > > > > >                (const_int 8 [0x8])) [0 D.11913.delay+0 S8 A64])
> > > > > > > > >        (nil)))
> > > > > > > > > ../fdmgr/fdmgr.cpp:152: confused by earlier errors, bailing out
> > > > > > > > > 
> > > > > > > > > With -O1 (or lower) it comliles the above but then fails here:
> > > > > > > > > 
> > > > > > > > > ../../src/misc/pv/typeCast.h: In function
> > > > > > > 
> > > > > > >  'void<unnamed>::castVTyped(size_t,
> > > > > > > > void*, const void*) [with TO = std::basic_string<char, std::char_traits<char>,
> > > > > > > > std::allocator<char> >, FROM = float]':
> > > > > > > > > ../../src/misc/pv/typeCast.h:195: sorry, unimplemented: inlining failed in
> > > > > 
> > > > >  call
> > > > > > > > to 'TO epics::pvData::castUnsafe(const FROM&) [with TO =
> > > > > > > > std::basic_string<char, std::char_traits<char>, std::allocator<char> >, FROM
> > > > > 
> > > > >  =
> > > > > > > > float]': recursive inlining
> > > > > > > > > ../../src/misc/typeCast.cpp:38: sorry, unimplemented: called from here
> > > > > > > > > 
> > > > > > > > > At least the compiler is "sorry".  I feel much better.
> > > > > > > > > 
> > > > > > > > > BTW: VxWorks 6.7 has no such problems.
> > > > > > > > > 
> > > > > > > > > Dirk
> > > > > > > > > 
> > > > > > 
> > > > > >  
> > > > 
> > > >  
> > > 
> > > -- 
> > > Complexity comes for free, simplicity you have to work for.
> > > 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System