SPEC CPU Flags Description file for HP HP-UX March 2010 Compilers

Perform minimal optimizations.

Perform optimizations within basic blocks only.

Perform level 1 as well as function level global optimizations, and intramodule interprodedural optimizations, including function inlining. Same as -O.

Perform level 2 as well as additional loop nest optimizations.

Perform level 3 as well as doing interprocedural optimizations across translation units (link time optimizations). See -ipo.

Enable interprocedural optimizations across files. This option is ignored at optimization levels +O0 and +O1. It is enabled by default when +O4 or +Ofaster are used. NOTE: Object files produced using this option contain intermediate code in the IELF format. At link time, ld automatically invokes the interprocedural optimizer u2comp if any of the input object files is an IELF file. These IELF object files are intended to be temporary files. They are not guaranteed to be compatible from one version of the compiler to the next.

Instrument the application to enable collection of profile based optimization data. Qualifiers are a comma-separated list of profile collection qualifiers. The profile collection qualifiers are:

• arc - Enable collection of arc counts.
• dcache - Enable collection of data cache misses via hardware performance counters.
• stride - Enable collection of stride data.
• loopiter - Enable collection of loop iteration counts.
• all - Enable collection of all types of profile data. Equivalent to the command +Oprofile=collect:arc,dcache,stride,loopiter.

Examine the profile database file produced by an instrumented program to perform profile based optimizations on the code. Some optimizations are only enabled when a feedback data file is available.

This option selects +Ofast, but with the optimization level increased to +O4.

This option selects a combination of compilation and link options for optimum execution speed and reasonable build times. Currently implies the following:

This option selects a combination of compilation and link options for optimum execution speed and reasonable build times. Currently implies the following:

Specifies whether shared or archive libraries are searched with the -l option. For archive_shared, the archive form is preferred, but the shared form is allowed.

Request a particular virtual memory page size that should be used for instructions. Sizes of 4K, 16K, 64K, 256K, 1M, 4M, 16M, 64M, 256M, 1G, 4G, D, and L are supported. A size of D allows the kernel to choose what page size should be used. A size of L results in using the largest page size available. The actual page size may vary if the requested size cannot be fulfilled.

Request a particular virtual memory page size that should be used for data. Sizes of 4K, 16K, 64K, 256K, 1M, 4M, 16M, 64M, 256M, 1G, 4G, D, and L are supported. A size of D allows the kernel to choose what page size should be used. A size of L results in using the largest page size available. The actual page size may vary if the requested size cannot be fulfilled.

In 32-bit mode only, cause the data to be placed immediately following the text, and make the text writable. Files of this type cannot be shared.

Enable sudden underflow (flush to zero) of denormalized values.

Sets a flag in the executable which causes the dynamic loader to merge all data segments of shared libraries loaded at startup time into one block. Data segments for each dynamically loaded library will also be merged with the data segments of dependent libraries. This increases run-time performance by allowing the kernel to use larger size page table entries.

Use the instruction scheduler tuned to the model specified. The defined values for model are:

• blended - Tune for the best performance on a combination of processors (i.e. Itanium, Itanium2, or native processor).
• itanium - Tune for best performance on an Intel(R) Itanium(R) processor.
• itanium2 - Tune for best performance on a Intel(R) Itanium(R) 2 processor.
• native - Tune for best performance on the processor on which the compiler is running.

The default model is blended.

Controls the integer overflow assumptions made by the compiler to provide the best runtime performance. The defined values for type are:

• aggressive - Allows the compiler to make a broad set of assumptions so that the integer arithmetic expressions do not overflow.
• moderate - This is the same as aggressive except that the LFTR (linear function test replacement) optimization is not performed. The default at optimization levels 2, 3 and 4.
• conservative - Directs the compiler to make fewer assumptions so that the integer arithmetic expressions do not overflow.

Enable [disable] aliasing across types.

• off - The default. Specifies that aliasing can occur freely across types. This is a synonym to +Onoptrs_ansi and +Onoptrs_strongly_typed options in legacy cc.
• limited - Code follows ANSI aliasing rules. Unnamed objects should be treated as if they had an unknown type.
• ansi - Code follows ANSI aliasing rules, and unnamed objects should be treated the same as named objects. This option is synonym to +Optrs_ansi option in legacy cc.
• strong - Code follows ANSI aliasing rules, except that accesses through lvalues of a character type are not permitted to touch objects of other types. This assumes that field addresses are not taken. This option is synonym to +Optrs_strongly_typed option in legacy cc.

Controls the level of floating point optimizations that the compiler may perform. The defined values for level are:

• default - Allows contractions, such as fused multiply-add (FMA), but disallows any other floating point optimization that can result in numerical differences.
• limited - Like default, but also allows floating point optimizations which may affect the generation and propagation of infinities, NaNs, and the sign of zero.
• relaxed - In addition to the optimizations allowed by limited, permits optimizations, such as reordering of expressions, even if parenthesized, that may affect rounding error. This is the same as +Onofltacc.
• strict - Disallows any floating point optimization that can result in numerical differences. This is the same as +Ofltacc.

The default is +Ofltacc=default.

Use low-call-overhead versions of select library routines. This option can be used at any level. At optimization level 0 or 1, the default is +Onolibcalls; at optimization level 2 or higher, the default is +Olibcalls.

NOTE: This option is deprecated and may not be supported in future releases. On HP-UX HP Integrity Servers, including a system header file will cause the functions declared therein to be eligible for libcalls transformations, regardless of the state of +O[no]libcalls.

Do not suppress optimizations that significantly increase compile-time or consume enormous amounts of memory.

Link with the Next Generation Malloc library.

+Odataprefetch=kind

Control generation of data prefetch instructions for data structures referenced within innermost loops. The defined values for kind are:

• direct - Enable generation of data prefetch instructions for the benefit of direct memory accesses, but not indirect memory accesses.
• indirect - Enable generation of data prefetch instructions for the benefit of both direct and indirect memory accesses. This is the default at optimization levels +O2 and above.
• none - Disable generation of data prefetch instructions. This is the default at optimization levels +O1 and below.

Optimize with the assumption that subprogram arguments do [do not] refer to the same memory. This option can be used at optimization levels 2, 3, and 4.

Do not generate recovery code for control speculation. The default is +Orecovery. NOTE: For code which writes to uncacheable memory which may not be properly identified as volatile, the +Orecovery option reduces the risk of incorrect behavior.

Do not postpend underscores at the end of definitions of and references to externally visible symbols.

Invoke the HP ANSI C compiler in Extended ANSI mode. Same as -Aa -D_HPUX_SOURCE +e. This would define the names (macros and typedefs) provided by the HP-UX Operating System and, in addition, allows extensions such as C99 features in this release (complex and imaginary data types, STDC pragmas), $ characters in identifier names, sized enums, and sized bit-fields, and 64-bit integral types.

Invoke the HP aC++ compiler in ANSI mode. Turns on newly supported ANSI C++ Standard features like Koenig lookup and correct scoping for variables declared in conditional statements like for-loops.

Invoke the HP C compiler in partial support for the C99 Standard mode. ANSI programming language C standard ISO/IEC 9899:1999

Invoke the HP Fortran90 compiler.