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January 19, 2005
SGI® Altix™Introduction to Intel Compilers
Reiner VogelsangSGI GmbH
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Objectives
• After completion you understand –some fundamental optimizations of the Intel compiler and–the informations of the optimizer report provided by the
compiler
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New command line switches
Run-time checking (-check)
Floating point exception handling (-fpe)
Non-native I/O conversion (-convert)
Detect FP stack corruption (-fpstkchk)
Display traceback on errors (-trace)
Link in threaded libraries (-threads)
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Compiler Directives
Fortran:cdir$ ivdep
cdir$ swp
cdir$ noswp
cdir$ loop count (NN)
cdir$ distribute point
cdir$ unroll (n)
cdir$ nounroll
cdir$ prefetch a
cdir$ noprefetch c
no aliasing
try to software-pipeline
disable software-pipelining
hint for SWP
split this large loop
unroll n times
do not unroll
prefetch array “a”
do not prefetch array “c”
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Compiler Directives
C/C++:#pragma ivdep
#pragma swp
#pragma noswp
#pragma loop count (NN)
#pragma distribute point
#pragma unroll (n)
#pragma nounroll
#pragma prefetch a
#pragma noprefetch c
no aliasing
try to software-pipeline
disable software-pipelining
hint for SWP
split this large loop
unroll n times
do not unroll
prefetch array “a”
do not prefetch array “c”
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