IPF_intel91_flags
SPEC CPU2006 Flag Description for the Intel(R) C++ Compiler 9.1
and the Intel(R) Fortran Compiler 9.1 for IPF Linux64
Copyright © 2006 Intel Corporation. All Rights Reserved.
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Invoke the Intel C++ compiler for IPF Linux64 to compile C applications
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Invoke the Intel C++ compiler for IPF Linux64 to compiler C++ applications
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Invoke the Intel Fortran compiler for IPF Linux64
Invoke the Intel C++ compiler in C99 mode for IPF Linux64
Disable all warnings. Display error messages only.
For mixed-language benchmarks, tell the compiler that the main program is not written in Fortran
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Enables optimizations for speed and disables some optimizations that
increase code size and affect speed.
To limit code size, this option:
- Enables global optimization; this includes data-flow analysis,
code motion, strength reduction and test replacement, split-lifetime
analysis, and instruction scheduling.
- Disables intrinsic recognition and intrinsics inlining.
The O1 option may improve performance for applications with very large
code size, many branches, and execution time not dominated by code within loops.
On IPF Linux64 platforms, -O1 disable software pipelining and global code scheduling.
On Intel Itanium processors, this option also enables optimizations for server applications
(straight-line and branch-like code with a flat profile).
-unroll0, -fbuiltin, -mno-ieee-fp, -fomit-frame-pointer (same as -fp), -ffunction-sections
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Enables optimizations for speed. This is the generally recommended
optimization level. This option also enables:
- Inlining of intrinsics
- Intra-file interprocedural optimizations, which include:
- inlining
- constant propagation
- forward substitution
- routine attribute propagation
- variable address-taken analysis
- dead static function elimination
- removal of unreferenced variables
- The following capabilities for performance gain:
- constant propagation
- copy propagation
- dead-code elimination
- global register allocation
- global instruction scheduling and control speculation
- loop unrolling
- optimized code selection
- partial redundancy elimination
- strength reduction/induction variable simplification
- variable renaming
- exception handling optimizations
- tail recursions
- peephole optimizations
- structure assignment lowering and optimizations
- dead store elimination
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Enables O2 optimizations plus more aggressive optimizations,
such as prefetching, scalar replacement, and loop and memory
access transformations. Enables optimizations for maximum speed,
such as:
- Loop unrolling, including instruction scheduling
- Code replication to eliminate branches
- Padding the size of certain power-of-two arrays to allow
more efficient cache use.
On Intel Itanium processors, the O3 option enables optimizations
for technical computing applications (loop-intensive code):
loop optimizations and data prefetch.
The O3 optimizations may not cause higher performance unless loop and
memory access transformations take place. The optimizations may slow
down code in some cases compared to O2 optimizations.
The O3 option is recommended for applications that have loops that heavily
use floating-point calculations and process large data sets.
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This option enables additional interprocedural optimizations for single
file compilation. These optimizations are a subset of full intra-file
interprocedural optimizations. One of these optimizations enables the
compiler to perform inline function expansion for calls to functions
defined within the current source file.
Multi-file ip optimizations that includes:
- inline function expansion
- interprocedural constant propogation
- dead code elimination
- propagation of function characteristics
- passing arguments in registers
- loop-invariant code motion
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The -fast option enhances execution speed across the entire program
by including the following options that can improve run-time performance:
-O3 (maximum speed and high-level optimizations)
-ipo (enables interprocedural optimizations across files)
-static (link libraries statically)
To override one of the options set by /fast, specify that option after the
-fast option on the command line. The options set by /fast may change from
release to release.
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Instrument program for profiling for the first phase of
two-phase profile guided otimization. This instrumentation gathers information
about a program's execution paths and data values but does not gather
information from hardware performance counters. The profile instrumentation
also gathers data for optimizations which are unique to profile-feedback
optimization.
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Instructs the compiler to produce a profile-optimized
executable and merges available dynamic information (.dyn)
files into a pgopti.dpi file. If you perform multiple
executions of the instrumented program, -Qprof_use merges
the dynamic information files again and overwrites the
previous pgopti.dpi file.
Without any other options, the current directory is
searched for .dyn files
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Tells the compiler the maximum number of times (n) to unroll loops.
Enables inline expansion of all intrinsic functions.
Disables conformance to the ANSI C and IEEE 754 standards for
floating-point arithmetic.
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Allows use of EBP as a general-purpose register in optimizations.
Places each function in its own COMDAT section.
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Specifies the level of inline function expansion.
Ob0 - Disables inlining of user-defined functions. Note that
statement functions are always inlined.
Ob1 - Enables inlining when an inline keyword or an inline
attribute is specified. Also enables inlining according
to the C++ language.
Ob2 - Enables inlining of any function at the compiler's
discretion.
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-static prevents linking with shared libraries.
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This option enables read only string-pooling optimization.
This option enables read/write string-pooling optimization.
This option disables stack-checking for routines with 4096 bytes
of local variables and compiler temporaries.
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Enable SmartHeap library usage by forcing the linker to
ignore multiple definitions
Enable SmartHeap library usage by forcing the linker to
ignore multiple definitions
-inline-factor=n
Specifies the percentage multiplier that should be applied to all inlining
options that define upper limits: -inline-max-size, -inline-max-total-size,
-inline-max-per-routine, and -inline-max-per-compile.
This option takes the default value for each of the above options
and multiplies it by n divided by 100. For example, if 200 is specified,
all inlining options that define upper limits are multiplied by a factor of 2.
n is a positive integer specifying the percentage value. The default value
is 100 (a factor of 1).
Disables the insertion of software prefetching by the compiler.
Enables use of faster but slightly less accurate code sequences for math functions,
including sqrt, reciprocal sqrt, divide and reciprocal. When compared to strict IEEE*
precision, this option slightly reduces the accuracy of floating-point calculations
performed by these functions, usually limited to the least significant digit.
This option also performs reassociation transformations, which can alter the order of
operations, over a larger scope. The increased reasssociation enables generation of
more optimal sequences of Floating point Multiply Add instructions than not using
this option. Note that use of Floating point Multiply Add can cause programs to
produce different numerical results due to changes in rounding.
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Tells the compiler to assume the program does adhere to
to the Fortran 95 Standard type
aliasability rules (default).
Specifies that aliasing should not be assumed in the program.
Do not assume arguments may be aliased.
Tells the compiler to assume the program does adhere to
the rules defined in the ISO C Standard. The default is to not assume such
adherence. If your C/C++ program adheres to these
rules, then -ansi-alias will allow the compiler to optimize
more aggressively. If it doesn't adhere to these
rules, then assuming so can cause the compiler to generate
incorrect code.
The -Wl option directs the compiler to pass a list of arguments
to the linker. In this case, "-z muldefs" is passed to the
linker. For the Gnu linker (ld), the "-z keyword" option accepts
several recognized keywords. Keyword "muldefs" allows multiple
definitions. The muldefs keyword will enable, for example,
linking with third party libraries like SmartHeap from
Microquill.
MicroQuill SmartHeap Library available from http://www.microquill.com/
MicroQuill SmartHeap Library for C++ (must be linked with libsmartheap64.a).
available from http://www.microquill.com/
Specifies that the application should run within a 32-bit address space.
Also tells the compiler to use 32-bit pointers whenever possible. To use
this option, you must specify -ipo.
Enable the auto-parallelizer to generate multi-threaded code for loops
that can be safely executed in parallel. The -parallel option enables
the auto-parallelizer if either the -O2 or -O3 optimization option is
also on (the default is -O2).
-opt-mem-bandwidth n
Enables or disables performance tuning and heuristics that control memory
bandwidth use among processors. It allows the compiler to be less aggres-
sive with optimizations that might consume more bandwidth, so that the band-
width can be well-shared among multiple processors for a parallel program.
For values of n greater than 0, the option tells the compiler to enable a
set of performance tuning and heuristics in compiler optimizations such as
prefetching, privatization, aggressive code motion, and so forth, for reduc-
ing memory bandwidth pressure and balancing memory bandwidth traffic among
threads. The n value is the level of optimizing for memory bandwidth
usage. You can specify one of the following values for n:
0 -- Disables a set of performance tuning and heuristics in compiler opti-
mizations for parallel code. This is the default for serial code.
1 -- Enables a set of performance tuning and heuristics in compiler opti-
mizations for multithreaded code generated by the compiler. This is the
default if compiler option -parallel or -openmp is specified, or Cluster
OpenMP option -cluster-openmp is specified (see the Cluster OpenMP documen-
tation).
2 -- Enables a set of performance tuning and heuristics in compiler opti-
mizations for parallel code such as Windows Threads, pthreads, and MPI code,
besides multithreaded code generated by the compiler.