PGI User's Guide

Getting Started with Optimizations–help–Minfo26As described in “Help with Command-line Options,” on page 18, you can see a specification of any commandlineoption by invoking any of the PGI compilers with -help in combination with the option in question,without specifying any input files.For example, you might want information on -O:$ pgfortran -help -OThe resulting output is similar to this:Reading rcfile /usr/pgi/linux86-64/7.0/bin/.pgfortranrc-O[] Set optimization level, -O0 to -O4, default -O2Or you can see the full functionality of -help itself, which can return information on either an individualoption or groups of options:$ pgfortran -help -helpThe resulting output is similar to this:Reading rcfile /usr/pgi_rel/linux86-64/7.0/bin/.pgfortranrc-help[=groups|asm|debug|language|linker|opt|other|overall|phase|prepro|suffix|switch|target|variable]You can use the -Minfo option to display compile-time optimization listings. When this option is used, thePGI compilers issue informational messages to stderr as compilation proceeds. From these messages, youcan determine which loops are optimized using unrolling, SSE instructions, vectorization, parallelization,interprocedural optimizations and various miscellaneous optimizations. You can also see where and whetherfunctions are inlined.–Mneginfo–dryrunFor more information on –Minfo, refer to “Optimization Controls” in the PGI Compiler Reference Manual.You can use the -Mneginfo option to display informational messages listing why certain optimizations areinhibited.For more information on –Mneginfo, refer to “Optimization Controls” in the PGI Compiler ReferenceManual.The –dryrun option can be useful as a diagnostic tool if you need to see the steps used by the compiler driverto preprocess, compile, assemble and link in the presence of a given set of command line inputs. When youspecify the –dryrun option, these steps will be printed to stderr but are not actually performed. For example,you can use this option to inspect the default and user-specified libraries that are searched during the linkphase, and the order in which they are searched by the linker.