[Vm-dev] '-DNDEBUG=0' and '-DDEBUGVM=1'

[Mariano Martinez Peck]

On Tue, Apr 26, 2011 at 7:40 PM, Eliot Miranda <eliot.miranda at gmail.com>wrote:

>
>
>
> On Tue, Apr 26, 2011 at 10:29 AM, Igor Stasenko <siguctua at gmail.com>wrote:
>
>>
>> On 26 April 2011 19:01, Eliot Miranda <eliot.miranda at gmail.com> wrote:
>> >
>> >
>> >
>> > On Tue, Apr 26, 2011 at 6:21 AM, Igor Stasenko <siguctua at gmail.com>
>> wrote:
>> >>
>> >> On 26 April 2011 04:03, Eliot Miranda <eliot.miranda at gmail.com> wrote:
>> >> >
>> >> >
>> >> >
>> >> > On Mon, Apr 25, 2011 at 6:39 PM, Igor Stasenko <siguctua at gmail.com>
>> wrote:
>> >> >>
>> >> >> On 26 April 2011 03:05, Mariano Martinez Peck <
>> marianopeck at gmail.com> wrote:
>> >> >> >
>> >> >> > Hi guys. I don't know why but with CMakeVMMaker the asserts are
>> not working.  I can see the flags are being set correct in CmakeList.txt:
>> >> >> >
>> >> >> > add_definitions(-arch i386 -mmacosx-version-min=10.5 -g3 -O0
>> -msse3 -funroll-loops -fasm-blocks -finline-functions -mfpmath=sse
>> -march=pentium-m -falign-functions=16 -fno-gcse -fno-cse-follow-jumps
>> -std=gnu99 -DBUILD_FOR_OSX -DUSE_INLINE_MEMORY_ACCESSORS -DLSB_FIRST
>> -DHAVE_SYS_TIME_H -DHAVE_NANOSLEEP -DNDEBUG=1 -DDEBUGVM=1 -DCOGMTVM=1
>> -DUSE_GLOBAL_STRUCT=0 -DBASE_HEADER_SIZE=4 -DCOGVM)
>> >> >> >
>> >> >>
>> >> >> AFAIK, code checks
>> >> >>
>> >> >> #ifdef NDEBUG
>> >> >>
>> >> >>
>> >> >> which means
>> >> >> 'if defined NDEBUG'
>> >> >>
>> >> >> and so it doesn't matters if it = 1 or = 0
>> >> >> because it is defined, but don't cares which value.
>> >> >>
>> >> >> Also,
>> >> >> NDEBUG and DEBUGVM should be mutually exclusive?
>> >> >
>> >> > NO!!  NO!!  NO!!  [ :) ].  I said earlier, NDEBUG is a linux-ism for
>> enabling asserts.  See /usr/include/assert.h.  So if defined(NDEBUG)
>> assert(foo) does nothing, but if !defined(NDEBUG) assert(foo) prints a
>> warning and in unix/linux aborts, but in Cog continues.
>> >> > DEBUGVM includes some extra code that allows break-pointing jumping
>> from the interpreter into machien code.  Arguably it could be eliminated but
>> it'll be useful when we port to new ISAs.
>> >> > I said all this last week.  Please take note this time :)
>> >>
>> >>
>> >> But hey, i insist that they are mutually exclusive.
>> >
>> > You can insist all you like but you're wrong.  NDEBUG controls
>> assertions and these are orthogonal to the enilopmart debugging introduced
>> by using DEBUGVM.  Simple as that.  They are *not* mutually exclusive.
>> >
>>
>> Eliot, i understand this stuff. Now you taking my words too literally.
>> I meant to say that for existing cmake configurations they should be
>> mutually exclusive.
>>
>
> Ah, agreed :)  Sorry :)
>
>
>>
>> But for current variants for release we should have:
>>  a) turn debugging off  (-DDEBUGVM=0)
>>  b) suppress assertions (-DNDEBUG)
>>
>> and when building VM for debugging we doing otherwise:
>>  - turn all debugging on (-DDEBUGVM=1)
>>  - enable assertions (omit defining -DNDEBUG)
>>
>>

Yes, exactly. Finally I understood. So...I will commit the fix becuase now
CMake confs are wrong.

Cheers

Mariano



> so in the above two configurations its easy to see that these two
>> options are mutually exclusive.
>>
>> And of course, in case of need, one can create configuration where you
>> can use different combination of these two flags, but the above two is
>> most logical choice for release and debug versions of VM configs.
>>
>>
>> --
>> Best regards,
>> Igor Stasenko AKA sig.
>>
>
>
>


-- 
Mariano
http://marianopeck.wordpress.com
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