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Dell
SPEC CPU2000 Flags Descriptions
Intel C/C++/Visual FORTRAN Compilers Version 8.0
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General Options (C/C++/FORTRAN)
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-O{1|2|3} Optimization-level options:
1: optimize for speed, but disable some optimizations that
increase code size for a small speed benefit. Includes
inline expansion for intrinsic functions, global
optimizations, string pooling optimizations.
2: optimizes for speed (DEFAULT). 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.
-Qax{K|W|N|B|P}
(IA-32 only)
Generates specialized code for processor-specific codes (see -Qx)
while also generating generic IA-32 code.
-Qx{K|W|N|B|P}
(IA-32 only)
Generates specialized code for processor specific codes:
K: Streamng SIMD Extensions (SSE)
W: Intel processor with Streamng SIMD Extensions 2 (SSE2)
N: Intel processor with Streamng SIMD Extensions 2 (SSE2)
B: Intel processor with Streamng SIMD Extensions 2 (SSE2)
P: Intel processor with Streamng SIMD Extensions 3 (SSE3)
Notes:
-Qx{N|B|P} and -Qax{N|B|P}:
These options also enable advanced data layout and code restructuring
optimizations to improve memory accesses for Intel processors.
-Qx{N|B|P}:
Programs, where the function main()is compiled with these
options, will detect non-compatible processors and generate
an error message during execution.
-Qip Enable single-file IP optimizations (within files, same as -Ob2).
-Qipo Enable multi-file IP optimizations (between files).
- inline function expansion
- interprocedural constant propogation
- dead code elimination
- propagation of function characteristics
- passing arguments in registers
- loop-invariant code motion
-Qprof_gen Instrument program for profiling for the first phase of
two-phase profile guided optimization.
-Qprof_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.
-Qrcd The Intel compiler uses the -Qrcd option to improve the
performance of code that requires floating-point-to-integer
conversions.
The system default floating point rounding mode is
round-to-nearest. This means that values are rounded during
floating point calculations. However, the C language requires
floating point values to be truncated when a conversion to an
integer is involved. To do this, the compiler must change the
rounding mode to truncation before each floating
point-to-integer conversion and change it back afterwards.
The -Qrcd option disables the change to truncation of the
rounding mode for all floating point calculations, including
floating point-to-integer conversions. Turning on this option
can improve performance, but floating point conversions to
integer may not conform to C semantics.
-Qunroll[n]
Specifies the maximum number of times to unroll a loop. Omit n
to let the compiler decide whether to perform unrolling or not.
Use n = 0 to disable unroller.
-Qwp_ipo Additionally to -Qipo, makes the whole program assumption that
all variables and functions seen in compiled sources are
referenced only within those sources; the user must guarantee
that this assumption is safe.
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Flags Specific to C/C++
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-G{5|6|7} Optimize code specifically for a targeted processor. Includes
one or more of the following characters:
5: Pentium processors with or without MMX technology
6: Pentium Pro, Pentium II, and Pentium III processors
7: Pentium 4 processor
-GR[-] Enables [disables (DEFAULT)] C++ Runtime Type Information (RTTI).
-GX[-] Enables [disables (DEFAULT)] C++ exception handling.
-Oi[-] Enables (DEFAULT) [disables] inline expansion of standard
library functions.
-Zp(1|2|4|8|16)
Use the -Zp{n} option to determine the alignment constraint for structure
declarations, on n-byte boundary (n = 1, 2, 4, 8, 16). Generally, smaller
constraints result in smaller data sections while larger constraints
support faster execution.
For example, to specify 2 bytes as the alignment constraint for all
structures and unions in the file prog1.c, use the following command:
<compiler> -Zp2 prog1.c
The default is -Zp16.
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Flags Specific to FORTRAN
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-Ob{0|1|2} Controls the compiler's inline expansion.
0: disable inlining.
1: disables inlining unless /Qip or /Ob2 are specified.
2: enables inlining of any function.
However, the compiler decides which functions are inlined.
This option enables interprocedural optimizations
and has the same effect as specifying the /Qip option.
-Qauto Causes all variables to be allocated on the stack, rather than
in local static storage.
-Qprefetch[-]
Enable [disable (DEFAULT)] prefetch insertion. The default
with -O3 is -Qprefetch.
-Qscalar_rep[-]
Enables (DEFAULT) [disables] scalar replacement performed
during loop transformations.
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Miscellaneous
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The starting tokens "/" and "-" are both equivalent for flags passed to the
compiler. For example, -QxW and /QxW are identical switches.
+FDO PASS1= -Qprof_gen PASS2= -Qprof_use
Using feedback-directed optimization, a profile is generated
on the first pass of compilation and used on the second pass.
shlW32M.lib
MicroQuill SmartHeap Library 7.1 available from
www.microquill.com
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Portability Options For CPU2000
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176.gcc:
-Dalloca=_alloca So as to use the built-in optimized alloca.
/F10000000 176.gcc uses alloca and this option tells the
linker to pre-allocate 10MB of stack. The default
amount of stack allocated is not enough and 176.gcc
crashes with a run-time error
178.galgel:
/FI Fixed-format F90 source code.
/F32000000 Same as with 176.gcc, pre-allocates a 32MB stack
186.crafty:
-DNT_i386 Specifies that it is a Windows NT Intel processor-based
system which makes the compiler use "_int64"
as the 64-bit variable that 186.crafty needs.
253.perlbmk:
-DSPEC_CPU2000_NTOS This enables the code changes for porting to
Windows get included.
-DPERLDLL On Windows, we need a perl.exe instead of a
perl.exe and perl.dll. This pre-defines ensures
that the changes necessary to get a single, UNIX-style
executible without getting the indirect calls that
can cause a 10% performance degradation. This allows
the Windows-based executible to be as close as possible
to the Unix-based one.
/MT Use the static multi-threaded library else it
will not compile.
254.gap:
-DSYS_HAS_CALLOC_PROTO
-DSYS_HAS_MALLOC_PROTO
These two pre-defines tell of the existence of
malloc and calloc prototypes.