XL Fortran Enterprise Edition for AIX : User's Guide - IBM

Table 5. Options for Performance Optimization (continued)
Command-Line
Option
@PROCESS
Directive
-qcache={
auto |
assoc=number |
cost=cycles |
level=level |
line=bytes |
size=Kbytes |
type={C|c|D|d|I|i}}[:...]
-qcompact
-qnocompact
-qdirectstorage
-qnodirectstorage
-qessl
-qfdpr
-qnofdpr
-qhot[=suboptions]
-qnohot
-qipa[=suboptions]
| -qnoipa
-qkeepparm
-qnokeepparm
COMPACT
NOCOMPACT
HOT[=suboptions]
NOHOT
Description
Specifies the cache configuration for a
specific execution machine. The compiler
uses this information to tune program
performance, especially for loop operations
that can be structured (or blocked) to process
only the amount of data that can fit into
the data cache.
Default: The compiler uses typical values
based on the -qtune setting, the -qarch
setting, or both settings.
Reduces optimizations that increase code
size.
Default: -qnocompact
Informs the compiler that a given
compilation unit may reference
write-through-enabled or cache-inhibited
storage. Use this option with discretion. It
is intended for programmers who know
how the memory and cache blocks work,
and how to tune their applications for
optimal performance.
Default: -qnodirectstorage
Allows the use of ESSL routines in place of
Fortran 90 Intrinsic Procedures. Use the
ESSL Serial Library when linking with
-lessl. Use the ESSL SMP Library when
linking with -lesslsmp.
Default: -qnoessl
Provides object files with information
needed for theAIX fdpr (Feedback Directed
Program Restructuring) performance-tuning
utility to optimize the resulting executable
file.
Default: -qnofdpr
The -qhot compiler option is a powerful
alternative to hand tuning that provides
opportunities to optimize loops and array
language. The -qhot compiler option will
always attempt to optimize loops,
regardless of the suboptions you specify.
Default: -qnohot
Enhances -O optimization by doing
detailed analysis across procedures
(interprocedural analysis or IPA).
Default: -O analyzes each subprogram
separately, ruling out certain optimizations
that apply across subprogram boundaries.
Note that specifying -O5 is equivalent to
specifying -O4 and -qipa=level=2.
Ensures that incoming procedure
parameters are stored on the stack even
when optimizing.
Default: -qnokeepparm
See
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72 XL Fortran Enterprise Edition for AIX : User’s Guide