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Blitz Support : |
From: Einar Otnes (eiot_at_[hidden])
Date: 2003-07-25 01:28:25
Julian,
I'm glad you're looking into the problem which I think is rather important
when it comes to optimizing the code. As far as I have understood compiling
with -DBZ_DEBUG will slow down the array operations tremendously since each
array element is checked with the array boundaries. From what I've seen
from earlier replies this problem can be resolved by including "
-strict_induction" when compiling. This option disables loop induction
variable optimizations and is generally not recommended because it can
cause considerable performance degradation. We are then left with a
suboptimized code using blitz arrays in order to make it work which is not
what Blitz++ is supposed to be...
Thanks,
Einar Otnes
Julian Cummings
<cummings_at_[hidden] To: Support list for Blitz++ <blitz-support_at_[hidden]>
> cc: (bcc: Einar Otnes)
Sent by: Subject: Re: [Blitz-support] Problems with SGI compiler and
blitz-support-bounces_at_oonu optimization
merics.org
24.07.2003 22:16
Please respond to Support
list for Blitz++
Hello Einar,
I've been looking into this problem you reported. It appears to me that
the key
change in the compilation options is adding -DBZ_DEBUG, not switching from
optimization to debug flags. By just adding -DBZ_DEBUG to your set of
optimization compiler flags, you should see that your code works properly.
-DBZ_DEBUG mostly activates some Blitz assertions that are sprinkled
throughout
the code. I'm in the process of trying to narrow down what causes the
change in
behavior. It is probably something in the expression evaluator code.
Regards, Julian C.
Einar Otnes wrote:
>I am struggling using Blitz++-0.6 on the SGI 7.3.1.3m compiler using -O3
>optimization option. The code compiles fine, but the output results are
>just zero. When using the debugging option things are working fine. I have
>attached a simple program that exhibits this behaviour. Here, we get a
>problem with initializing the array which is zero after calling the init
()
>routine. Is this a problem with the SGI compiler? Or am I doing something
>wrong?
>I have yet to try this example on the Intel Linux compiler.
>
>
> The program and the Makefile is listed below:
>
>Thanks
>Einar Otnes
>
>
>#include <iostream>
>#include <string>
>#include <blitz/array.h>
>
>namespace EPL
>{
>template<typename T>
> class Field
> {
> public:
>
> Field(int M, int N)
> {
> init(M,N);
> }
>
> protected:
>
> blitz::Array<T,2> dataArr;
>
>
> void init(int M, int N){
>
> // Initialize the array. Does not work when compiling with -O3.
>Sometimes this problem can be solved by
> // using for loops for initialization working on the array
>elementwise.
> dataArr.resize(M,N);
> dataArr = 0.34*blitz::tensor::i;
> }
>
> };
>
>
>template<typename T>
> class BnField : public Field<T>
> {
> public:
>
> BnField(int M, int N):Field<T>(M,N)
> {
> std::cerr << "Hello World!" << std::endl;
> }
>
> void multiplySelf(){
>
> T number(1,2);
> dataArr = number*dataArr;
> }
>
>
> void printAll(){
>
> std::cerr << "dataArr = " << dataArr << std::endl;
> }
>
> };
>
>
>} // End namespace EPL
>
>
>// Main program starts here
>
>using namespace EPL;
>
>int main(int argc, char *argv[])
>{
>
> int M = 4;
> int N = 5;
>
> BnField<std::complex<float> > B1(M,N);
>
> B1.printAll();
>
> B1.multiplySelf();
>
> B1.printAll();
>
> return EXIT_SUCCESS;
>}
>
>
>
>The Makefile with the two different CXXFLAGS is given below. The code
works
>with the debugging option, but not without it.
>
>
>
># Path where Blitz++ is installed
>BZDIR = /private/eiot/Blitz++-0.6
>
>ARCH = mips64
>
>CXX = CC #-Bstatic
>
># Flags for optimized executables
>CXXFLAGS = -64 \
> -DBZ_DISABLE_XOPEN_SOURCE \
> -LANG:std -LANG:restrict \
> -I$(BZDIR)/include \
> -O3 -OPT:Olimit=0 -TENV:X=0 \
> -apo
>
>
>
># Flags for debugging
>#CXXFLAGS = -64 -g3 -DBZ_DEBUG \
># -DBZ_DISABLE_XOPEN_SOURCE \
># -LANG:std -LANG:restrict \
># -I$(BZDIR)/include \
># -apo
>
>
>LDFLAGS = -64 -lCio
>
>LIBS = -L$(BZDIR)/lib -lblitz \
> -lm -lCio \
> -apo
>
># Name of executable file
>EFILE = main
>
>OBJS = main.o
>
>main: $(OBJS)
> @echo "linking..."
> $(CXX) $(LDFLAGS) -o $(EFILE) $(OBJS) $(LIBS)
>
>$(OBJS): $(HDRS)
> $(CXX) $(CXXFLAGS) -c $*.cpp
>
>clean:
> rm -f $(OBJS) $(EFILE)
> rm -rf ii_files/
> rm -rf rii_files/
>
>main.o: main.cpp
>
>
>
>
>
>
>
>
>
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-- Dr. Julian C. Cummings E-mail: cummings_at_[hidden] California Institute of Technology Phone: 626-395-2543 1200 E. California Blvd., Mail Code 158-79 Fax: 626-584-5917 Pasadena, CA 91125 _______________________________________________ Blitz-support mailing list Blitz-support_at_[hidden] http://www.oonumerics.org/mailman/listinfo.cgi/blitz-support ------------------------------------------------------------------- The information contained in this message may be CONFIDENTIAL and is intended for the addressee only. Any unauthorised use, dissemination of the information or copying of this message is prohibited. If you are not the addressee, please notify the sender immediately by return e-mail and delete this message. Thank you.