|
Using PGO
To use profile-guided optimization, you must compile at least twice.
Follow these steps:
-
Instrumented compilation
Compile using the -Qprof_gen option
(-prof_gen on Linux*).
Example: prompt>icl -Qprof_gen
test.c
-
Instrumented execution
Run the application through a representative
workload to generate a profile. This step generates a data file
with a .dyn suffix.
Example: prompt>test.exe
-
Feedback compilation
Set the compiler to use the profile information the next time
you recompile the application, using the -Qprof_use
option (-prof_use on Linux). This step uses
the dynamic information (.dyn file) generated
in the previous step. Besides the optimization, the compiler produces
a pgopti.dpi file. You typically specify
the default optimizations (-O2) for phase
1, and specify more advanced optimizations (-Qip
or -Qipo) for phase 3.
Example: prompt>icl -Qprof_use
test.c
|
|