Sun Microsystems SPEC CPU Flags

[optimizer flag]

Increase the probability that the compiler will perform memcpy/memset transformations.

[optimizer]

Ignore parallelization factors in loop interchange heuristics.

[optimizer]

When considering whether to interchange loops, set memory store operation weight to n. A higher value of n indicates a greater performance cost for stores.

[optimizer flag]

Control the optimizer's loop inliner; set the minimum call site frequency counter in order to consider a routine for inlining.

[optimizer flag]

Control the optimizer's loop inliner; Set inline callee size limit to n. The unit roughly corresponds to the number of instructions.

[optimizer flag]

Control the optimizer's loop inliner; The inliner is allowed to increase the size of the program by up to n%.

[optimizer flag]

Control the optimizer's loop inliner; Allow routines to increase by up to n. The unit roughly corresponds to the number of instructions.

[optimizer flag]

Control the optimizer's loop inliner; Perform maximum inlining (without considering code size increase).

[optimizer flag]

Control the optimizer's loop inliner; Allow routines that are called recursively to still be eligible for inlining.

[optimizer flag]

Inliner only considers routines smaller than n pseudo instructions as possible inline candidates.

[optimizer flag]

Increase the probability that loop induction variables will replaced, so that some extraneous code can be eliminated from loops.

[optimizer flag]

Ignore parallelization factors in loop distribution heuristics.

[optimizer flag]

Reconstruct array subscripts during memory allocation merging and data layout program transformation.

[optimizer flag]

Do speculative prefetching for link-list data structures; perform prefetching n iterations ahead.

[optimizer flag]

Do speculative prefetching for link-list data structures; do not attempt prefetching for innermost loops.

[optimizer flag]

Allow prefetching through up to n levels of indirect memory references.

Enable padding of arrays by n.

[optimizer flag]

Convert multiple short memory operations into single long memory operations.

[optimizer flag]

Perform loop tiling which is enabled by loop skewing. Loop skewing is a transformation that transforms a non-fully interchangeable loop nest to a fully interchangeable loop nest. The optional b<n> sets the tiling block size to n.

[optimizer flag]

Increase the probability that small-trip-count inner loops will be fully unrolled.

[optimizer flag]

Enable optimization of critical control paths

Assume data is naturally aligned.

Used for 403.gcc: allow use of compiler's internal builtin alloca.

Synonym for -xdepend.

Allows the compiler to assume that your code does not rely on setting of the errno variable.

A convenience option, this switch selects several other options that are described in this file.

A convenience option, this switch selects several other options that are described in this file.

A convenience option, this switch selects several other options that are described in this file.

A convenience option, this switch selects the following switches that are described in this file:

Allow faster math operations:

• ERRNO might not be set correctly (e.g. when a single instruction is used, such as sqrt)
• Do not check for certain error conditions on inputs to math operations
• Do not check for traps
• Do not check for signaling NaNs

Programs that depend upon strict IEEE 754 conformance should not use this option.

Enables the use of the fused multiply-add instruction. For the production release of Sun Studio 12, the recommended spelling of this switch is "-fma=fused". For pre-release versions, the same effect can be achieved via the spelling "-Wc,-fma=fused" (C) or "-Qoption cg -fma=fused" (C++, Fortran).

Enables the use of the fused multiply-add instruction.

Selects faster (but nonstandard) handling of floating point arithmetic exceptions and gradual underflow.

Controls simplifying assumptions for floating point arithmetic:

• -fsimple=0 permits no simplifying assumptions. Preserves strict IEEE 754 conformance.
• -fsimple=1 allows the optimizer to assume:
  • The IEEE 754 default rounding/trapping modes do not change after process initialization.
  • Computations producing no visible result other than potential floating-point exceptions may be deleted.
  • Computations with Infinity or NaNs as operands need not propagate NaNs to their results. For example, x*0 may be replaced by 0.
  • Computations do not depend on sign of zero.
• -fsimple=2 permits more aggressive floating point optimizations that may cause programs to produce different numeric results due to changes in rounding. Even with -fsimple=2, the optimizer still is not permitted to introduce a floating point exception in a program that otherwise produces none.

Evaluate float expressions as single precision.

Sets the IEEE 754 trapping mode to common exceptions (invalid, division by zero, and overflow).

Turns off all IEEE 754 trapping modes.

Includes symbols in the executable. If the optimization level is -xO3 or lower, some optimizations may be disabled when -g is present. At -xO4 or higher, full optimization is performed, even when -g is present.

Includes symbols in the executable. If the optimization level is -xO3 or lower, some optimizations may be disabled when -g0 is present. At -xO4 or higher, full optimization is performed, even when -g0 is present.

Links in a library of general purpose memory allocation routines which can be faster than those found in libc, at the expense of more virtual memory consumed.

This library provides faster versions of some common functions, such as malloc/free and bcopy.

Include a library containing chip-specific memory routines.

Include the optimized math library. This option usually generates faster code, but may produce slightly different results. Usually these results will differ only in the last bit.

Include a library with vectorized versions of some elementary mathematical functions.

Use STLport's Standard Library implementation instead of the default libCstd.

The libsunmath math library contains functions that are not specified by any standard but are useful in numerical software. It also contains many of the functions that are in libm.so.2 but not in libm.so.1.

Links in a library of "object caching" memory allocation routines which can be faster than those found in libc.

Do not allow C++ exceptions. A throw specification on a function is accepted but ignored; the compiler does not generate exception code.

With -O1, also spelled "-O", optimizations include: basic local and global optimizations, such as induction variable elimination, common subexpression elimination, constant propogation, register allocation, and basic block merging.

In addition to the optimizations at -O1, add global optimizations at the function level, loop unrolling, and software pipelining.

In addition to the optimizations at -O2: add automatic inlining of functions in the same file, and use optmization algorithms that may take significantly more compilation time or that do not have as high a probability of improving execution time, such as speculative code motion.

A synomym for -xO3.

[code generator flag]

There are several scheduling passes in the compiler. This option allows early passes to move instructions across call instructions.

[code generator flag]

Allow the enhanced pipeline scheduler (EPS) to use speculative (non-faulting) loads.

[code generator flag]

Use enhanced pipeline scheduling (EPS) and selective scheduling algorithms for instruction scheduling.

[code generator flag]

The number of live variables allowed at any given point is n more than the number of physical registers. Setting n to a significantly large number (e.g., 100) will disable register pressure heuristics in EPS.

[code generator flag]

Set the EPS window size, that is, the number of instructions it will consider across all paths when trying to find independent instructions to schedule a parallel group. Larger values may result in better run time, at the cost of increased compile time.

[code generator flag]

Sets the aggressiveness of the trace formation, where n is 4, 5, or 6. The higher the value of n, the lower the branch probability needed to include a basic block in a trace.

[code generator flag]

Turn on optimization to reduce branch after branch penalty: nops will be inserted to prevent one branch from occupying the delay slot of another branch.

[code generator flag]

Use profile feedback data to predict values and attempt to generate faster code along these control paths, even at the expense of possibly slower code along paths leading to different values. Correct code is generated for all paths.

[code generator flag]

Do function entry alignment at n-byte boundaries.

[code generator flag]

Peels the most frequent test branches/cases off a switch until the branch probability reaches less than 1/n. This is effective only when profile feedback is used

[code generator flag]

Control irregular loop prefetching; turns the module on (1) or off (0) (default is on for F90; off for C/C++)

[code generator flag]

Control irregular loop prefetching; sets the prefetch look ahead distance, in bytes. The default is 256.

[code generator flag]

Control irregular loop prefetching; a setting of "1" means force user settings to override internally computed values.

[code generator flag]

Control irregular loop prefetching; a setting of "1" means force the optimization to be turned on for all languages.

[code generator flag]

Insert indirect prefetches when the indirect access chain spans across basic blocks.

[code generator flag]

Indicates to the compiler to insert n extra prefetches for each indirect access in outer loops

[code generator flag]

Turns on prefetching for outer loops

[code generator flag]

Control irregular loop prefetching; use weak prefetches in the general loop prefetch.

[code generator flag]

Control irregular loop prefetching; sets the number of attempts at prefetching. If not specified, t=2 if -xprefetch_level=3 has been set; otherwise, defaults to t=1.

[code generator flag]

Specifies that all loops can be pipelined without needing to be concerned about loop-carried dependencies.

[code generator flag]

In pipelined loops, use floating point divide instructions for signed integer division.

[code generator flag]

Set number of outstanding prefetches in pipelined loops to <n>

[code generator flag]

Turn off prefetching in the prolog of modulo scheduled loops.

[code generator flag]

Turn off prefetching for stores in the pipeliner.

[code generator flag]

Turn off the use of strong prefetches in modulo scheduled loops.

[code generator flag]

Assert (to the pipeliner) that unsigned int computations will not overflow.

[code generator flag]

Reduce the probability that the compiler will hoist sethi insructions out of loops.

Allocate routine local variables on the stack.

Specifies the degree of conformance with the ISO C standard: -Xc indicates strict conformance, whereas -Xa indicates ISO C plus some K&R compatibility extensions.

Allows the compiler to perform type-based alias analysis at the specified alias level:

• basic assume that memory references that involve different C basic types do not alias each other.
• std assume aliasing rules described in the ISO 1999 C standard.
• strong in addition to the restrictions at the std level, assume that pointers of type char * are used only to access an object of type char; and assume that there are no interior pointers.

Allows the compiler to perform type-based alias analysis:

• any assumes that any type can alias any other
• simple assumes that fundamental types are not aliased
• compatible assumes that layout-incompatible types are not aliased.

Specifies which instructions can be used. Among the choices are:

• native Use the instructions available on the current processor
• generic Use instructions that are compatible with most SPARC processors
• ultra3cu Use instructions compatible with the UltraSPARC IIIcu processor
• v8plusa Use instructions that are available on the UltraSPARC processors
• v8plusb Use instructions that are available on the UltraSPARC III/IV processors
• sparcfmaf Allows use of the v8plusb set plus extensions for floating-point multiply-add

Turn on automatic parallelization for multiple processors.

Substitute intrinsic functions or inline system functions where profitable for performance.

xcache defines the cache properties for use by the optimizer. It can specify use of default assumptions ("generic"); use of whatever the compiler can assume about the current platform ("native"); or an explicit description of up to three levels of cache, using colon-separated specifiers of the form si/li/ai, where:

• si is the size of the cache, in kb
• li is the line size, in bytes
• ai is the associativity

xchip determines timing properties that are assumed by the compiler. It does not limit which instructions are allowed (see xtarget for that). Among the choices are:

• ultra3 Optimize for the UltraSPARC III processor
• ultra3cu Optimize for the UltraSPARC IIIcu processor
• sparc64vi Optimize for the SPARC64 VI processor
• native Optimize for the current processor
• generic Use timing properties for good performance on most SPARC processors

Analyze loops for inter-iteration data dependencies, and do loop restructuring.

Turn off inlining.

Perform optimizations across all object files in the link step:

• 0 = off
• 1 = on
• 2 = performs whole-program detection and analysis.

At -xipo=2, the compiler performs inter-procedural aliasing analysis as well as optimization of memory allocation and layout to improve cache performance.

Use inline expansion for math library, libm.

Select the optimized math library.

Link with Sun supplied licensed sunperf library.

Perform link-time optimizations, such as branch optimization and cache coloring.

Set maximum assumed data alignment to be at a 4 byte boundary and raise signal SIGBUS in the case of misaligned data accesses.

Specify optimization level n:

• -xO1 does only basic local optimizations (peephole.)
• -xO2 Do basic local and global optimizations, such as induction variable elimination, common subexpression elimination, constant propogation, register allocation, and basic block merging.
• -xO3 Add global optimizations at the function level, loop unrolling, and software pipelining.
• -xO4 Adds automatic inlining of functions in the same file.
• -xO5 Uses optmization algorithms that may take significantly more compilation time or that do not have as high a probability of improving execution time, such as speculative code motion.

If multiple arrays are placed in common, insert padding between them for better use of cache. n specifies the amount of padding to apply, in units that are the same size as the array elements. If no parameter is specified then the compiler selects one automatically.

Pad local variables, for better use of cache.

Set the preferred page size for running the program.

Set the preferred heap page size for running the program.

Set the preferred stack page size for running the program.

Allow generation of prefetch instructions. -xprefetch=yes and -xprefetch are synonyms for -xprefetch=auto,explicit. -xprefetch=no is a synonym for -xprefetch=no%auto,no%explicit

Generate indirect prefetches for data arrays accessed indirectly.

Adjust the compiler's assumptions about prefetch latency by the specified factor. Typically values in the range of 0.5 to 2.0 will be useful. A lower number might indicate that data will usually be cache resident; a higher number might indicate a relatively larger gap between the processor speed and the memory speed (compared to the assumptions built into the compiler).

Turn off prefetch instruction generation.

Control the level of searching that the compiler does for prefetch opportunities by setting n to 1, 2, or 3, where higher numbers mean to do more searching. The default for Sun Studio C, Sun Studio C++, and for gccfss is 1. The default for Sun Studio Fortran is 2.

Collect profile data for feedback-directed optimization. If an option directory is named, the feedback will be stored there.

When FDO is used, the training run gathers information regarding execution paths. As of the Sun Studio 11 version of the compiler suite, the training run gathers information about data values on SPARC systems, but not on x86 systems. Hardware performance counters are not used. FDO improves existing optimizations but does not introduce new classes of optimization.

For gccfss, profile collection works the same as Sun Studio on SPARC.

Use data collected for profile feedback. If an option directory is named, look for the feedback data there.

Analyze loops for reductions such as dot products, maximum and minimum finding.

Treat pointer-valued function parameters as restricted pointers.

Enables the use of non-faulting loads when used in conjunction with -xarch=v8plus. Assumes that no memory based traps will occur.

Selects options for architecture, chip timing, and cache sizes. These can also be controlled separately, via -xarch, -xchip, and -xcache, respectively. A wide variety of targets can be selected, including ultra3, ultra3cu, ultra3i, ultra3iplus, ultra4, ultra4plus, ultraT1, ultraT2, sparc64vi. In each case, appropriate options are selected for architecture, chip timing, and cache size to match that target.

If -xtarget=native is selected, options that are appropriate for the system where the compile is being done.

The default is -xtarget=generic, which sets the parameters for the best performance over most 32-bit platform architectures.

On Solaris SPARC systems, the default pointer size with -xtarget=native is 32-bit.

Enable unrolling loops n times where possible.

Allow the compiler to transform math library calls within loops into calls to the vector math library. Specifying -xvector is equivalent to -xvector=yes.

This library is necessary to get full implementation of _Complex data types on Solaris 8 and Solaris 9. It is not necessary (and should not be used) on Solaris 10.

Invoke the Sun Studio C++ Compiler

Invoke the Sun Studio C Compiler.

Invoke the Sun Studio Fortran 90 Compiler

Invoke GCC for SPARC Systems, targetting C++ programs, and automatically adding the C++ library. See http://cooltools.sunsource.net/gcc/ for more information.

Note: this compiler is sometimes referenced below as "g-plus-plus" due to a limitation in how SPEC reports flags (it uses the XML name, and under the XML specification, such names are not allowed to use plus signs). The actual spelling used on the command line is "g++".

Turns on verbose mode, showing how command options expand. Shows each component as it is invoked.

Controls compiler verbosity. There are several values that can be used with this flag:

[no%]diags

[Do not] Print the command line for each compilation pass

[no%]template

[Do not] Turn on the template instantiation verbose mode (sometimes called the "verify" mode). The verbose mode displays each phase of instantiation as it occurs during compilation.

[no%]version

[Do not] Direct the CC driver to print the names and version numbers of the programs it invokes.

%all

Invokes all of the above.

%none

-verbose=%none is the same as -verbose=no%template,no%diags,no%version.

The default is -verbose=%none.

Same as -verbose=diags.

This flag will cause the Sun Studio Fortran compiler to emit verbose messages.

Directs the compiler to print the name and version ID of each component as the compiler executes.

Same as -verbose=version.

Specify the -xjobs option to set how many processes the compiler creates to complete its work. Currently, -xjobs works only with the -xipo option. When you specify -xjobs=n, the interprocedural optimizer uses n as the maximum number of code generator instances it can invoke to compile different files.

This library is necessary to get functions used for accessing name services. As there are no network-enabled CPU2006 benchmarks, this flag should not be used.