------------------------------------------------------
ION Computer Systems, Inc.
SPEC CPU2000 Flags Description
Intel C/C++/FORTRAN Compilers Version 9.1
Linux
------------------------------------------------------
------------------------------------------------------
General Options (C/C++/FORTRAN)
------------------------------------------------------
-fast This option maximizes speed across the entire program by
including the following Options
-O3 -ipo -no-prec-div -static -xP
-O{1|2|3} Optimization-level options:
1: optimize for speed, but disable some optimizations which
increase code size for a small speed benefit. Includes
inline expansion for intrinsic functions, global
optimizations, string pooling optimizations.
2: This is the default level of optimization.
Optimizes for speed. The -O2 option includes O1
optimizations and in addition enables inlining of
intrinsics and more speed optimizations.
3: Builds on -01 and -02 optimizations by enabling high-level
optimization. This level does not guarantee higher performance
unless loop and memory access transformation take place. In
conjunction with -QaxK/-QxK and QaxW/QxW, this switch causes
the compiler to perform more aggressive data dependency
analysis than for -O2. This may result in longer compilation
times.
-Oa[-] Assume [do not assume] no aliasing in program.
-align
This option tells the compiler to analyze and reorder memory layout for variables
and arrays. It sets the alignment for objects of type long long, double, and
long double to values more suited to best performance. If you are not interacting
with system libraries or other libraries that are compiled without -align, this option
can improve performance by reducing misaligned accesses.
-ansi_alias
Enable/disable use of ANSI aliasing rules in
optimizations; user asserts that the program adheres to
these rules. The default for C++ is -Qansi_alias-
which is that aliasing rules are not assumed. The default for
the Fortran compiler is -Qansi_alias. For C++, the -Qansi_alias
flag will enable optimizations that would otherwise be
prevented by potential aliasing.
-auto_ilp32
Instructs the compiler to analyze the program to determine if there are
64-bit pointers which can be safely shrunk into 32-bit pointers.
-ipo 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
-msse3
Generates code for Intel Pentium 4 processors with Streaming SIMD
Extensions 3 (SSE3).
-no-prec-div[-]
Enables optimizations that give slightly less precise results than full IEEE division.
-prof_gen
Instrument program for profiling for the first phase of
two-phase profile guided optimization.
-prof_use
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.
-static
This option prevents linking with shared libraries. It causes the executable
to link all libraries statically.
-x<codes>
Generate specialized code for processor specified by <codes>
while also generating generic code.
<codes> includes one or more of the following:
K: Intel Pentium III or copmatible Intel processors (SSE)
W: Intel Pentium 4 and compatible Intel processors (SSE2)
N: Intel Pentium 4 and compatible Intel processors (SSE2)
Enables new optimizations in addition to Intel processor-specific
optimizations.
P: Intel Pentium 4 processors and compatible Intel processors with SSE3
B Intel Pentium M and compatible Intel processors (SSE2)
SSE is Streamng SIMD Extensions
Additional Notes on <codes> N and P:
------------------------------------
The N and P options target your program to run on Intel Pentium 4
and compatible Intel processors. The resulting code might
contain unconditional use of features that are not supported
on other processors. Programs, where the function main() is
compiled with this option, will detect non compatible processors
and generate an error message during execution. This option
also enables new optimizations in addition to Intel processor
specific optimizations.
These options also enable advanced data layout and code restructuring
optimizations to improve memory accesses for Intel processors.
------------------------------------------------------
Flags Specific to FORTRAN
------------------------------------------------------
-align all
Instructs compiler to align data items by adding padding bytes
wherever possible to obtain the natural alignment of data items
in common blocks, derived types, and record structures.
------------------------------------------------------
General Options
------------------------------------------------------
+FDO PASS1=-prof_gen PASS2=-prof_use
Using feedback-directed optimization, a profile is generated
on the first pass of compilation and used on the second pass.
------------------------------------------------------
Benchmark-Specific Portability Options
------------------------------------------------------
178.galgel:
-FI
Fixed-format F90 source code.
186.crafty:
-DLINUX_i386
Linux Intel system, use "long long" as 64bit variable.
252.eon:
-DHAS_ERRLIST
Tells that the system provides the "sys_nerr" and "sys_errlist[]" variables
253.perlbmk:
-DSPEC_CPU2000_LINUX_I386
Enable the code changes for porting to Linux on i386 architecture to be utilized
-DSPEC_CPU2000_NEED_BOOL
Use SPEC provided definition of the boolean type
-DSPEC_CPU2000_LP64
Compile using LP64 programming model.
254.gap:
-DSYS_IS_USG
Tells that the operating system is USG compliant
-DSPEC_CPU2000_LP64
Compile using LP64 programming model.
255.vortex:
-DSPEC_CPU2000_LP64
Compile using LP64 programming model.
------------------------------------------------------
BIOS Settings
------------------------------------------------------
Enhanced SpeedStep Disabled in BIOS
Select "Disabled" for maximum CPU speed. Select "Enabled" to
allow OS to reduce power consumption. Enabled by default.
Hardware Prefetcher Enabled in BIOS
Enables a processor mechanism that automatically fetches
data and instructions into the unified second-level cache.
Enabling this feature can result in higher performance on
some applications and operating systems. Enabled by default.
Adjacent Cache Line Prefetch Enabled in BIOS
Enables a processor mechanism to fetch the adjacent cache
line within an 128-byte sector that contains the data
needed due to a cache line miss.
Enabling this feature can result in higher performance on
some applications and operating systems. Enabled by default.