llvm dev - Jun 2013 - [LLVMdev] does clang and llvm take more time to compile c code

Hi, Ben
gcc version is: 4.7.0
clang version is: 3.2

The command options are:
1) clang
generated object files: clang -O3 -c *.c -o x.o
link:  clang  *.o -lm -o  mpeg2enc

2) gcc
generated object files: gcc -O3 -c *.c -o x.o
link:  gcc  *.o -lm -o  mpeg2enc


Yes, maybe it is the config introduced problems, I build it with enable
debug options.

Thanks!

Eric




On Thu, Jun 27, 2013 at 7:49 PM, Benjamin Kramer <benny.kra at
gmail.com>wrote:
>
> On 27.06.2013, at 13:40, Eric Lu <eirc.lew at gmail.com> wrote:
>
> > Hello, all
> >
> > When I compile mpeg2enc of Mediabench, it seems clang and llvm take
> longer time than gcc. I meausre the time as follow:
> >
> > gcc -O3   8.190s
> > clang  -O3  20.253s
> >
> > will this means clang and llvm are slower than gcc in compiling c
code.
>
> Possibly. The timings are useless without information about the versions
> of GCC and clang used and the build configuration (clang is extremely slow
> when built without optimization).
>
> - Ben
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On Thu, Jun 27, 2013 at 6:04 PM, Eric Lu <eirc.lew at gmail.com>
wrote:
> Hi, Ben
> gcc version is: 4.7.0
> clang version is: 3.2
>
> The command options are:
> 1) clang
> generated object files: clang -O3 -c *.c -o x.o
> link:  clang  *.o -lm -o  mpeg2enc
>
> 2) gcc
> generated object files: gcc -O3 -c *.c -o x.o
> link:  gcc  *.o -lm -o  mpeg2enc
>
>
> Yes, maybe it is the config introduced problems, I build it with enable
> debug options.
>
More the point did you build it optimized or unoptimized. Can you show
your configure/make commands?

-eric
> Thanks!
>
> Eric
>
>
>
>
> On Thu, Jun 27, 2013 at 7:49 PM, Benjamin Kramer <benny.kra at
gmail.com>
> wrote:
>>
>>
>> On 27.06.2013, at 13:40, Eric Lu <eirc.lew at gmail.com> wrote:
>>
>> > Hello, all
>> >
>> > When I compile mpeg2enc of Mediabench, it seems clang and llvm
take
>> > longer time than gcc. I meausre the time as follow:
>> >
>> > gcc -O3   8.190s
>> > clang  -O3  20.253s
>> >
>> > will this means clang and llvm are slower than gcc in compiling c
code.
>>
>> Possibly. The timings are useless without information about the
versions
>> of GCC and clang used and the build configuration (clang is extremely
slow
>> when built without optimization).
>>
>> - Ben
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

The options is
cmake -DCMAKE_BUILD_TYPE="Debug" 
-DCMAKE_INSTALL_PREFIX=~software/llvmsvn
-DCMAKE_EXPORT_COMPILE_COMMANDS=ON /home/xxx/lsoftware/llvm-3.2-svn

$make
$make install


On Fri, Jun 28, 2013 at 12:37 PM, Eric Christopher <echristo at
gmail.com>wrote:
> On Thu, Jun 27, 2013 at 6:04 PM, Eric Lu <eirc.lew at gmail.com>
wrote:
> > Hi, Ben
> > gcc version is: 4.7.0
> > clang version is: 3.2
> >
> > The command options are:
> > 1) clang
> > generated object files: clang -O3 -c *.c -o x.o
> > link:  clang  *.o -lm -o  mpeg2enc
> >
> > 2) gcc
> > generated object files: gcc -O3 -c *.c -o x.o
> > link:  gcc  *.o -lm -o  mpeg2enc
> >
> >
> > Yes, maybe it is the config introduced problems, I build it with
enable
> > debug options.
> >
>
> More the point did you build it optimized or unoptimized. Can you show
> your configure/make commands?
>
> -eric
>
> > Thanks!
> >
> > Eric
> >
> >
> >
> >
> > On Thu, Jun 27, 2013 at 7:49 PM, Benjamin Kramer <benny.kra at
gmail.com>
> > wrote:
> >>
> >>
> >> On 27.06.2013, at 13:40, Eric Lu <eirc.lew at gmail.com>
wrote:
> >>
> >> > Hello, all
> >> >
> >> > When I compile mpeg2enc of Mediabench, it seems clang and
llvm take
> >> > longer time than gcc. I meausre the time as follow:
> >> >
> >> > gcc -O3   8.190s
> >> > clang  -O3  20.253s
> >> >
> >> > will this means clang and llvm are slower than gcc in
compiling c
> code.
> >>
> >> Possibly. The timings are useless without information about the
versions
> >> of GCC and clang used and the build configuration (clang is
extremely
> slow
> >> when built without optimization).
> >>
> >> - Ben
> >
> >
> >
> > _______________________________________________
> > LLVM Developers mailing list
> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >
>
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