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HP C

HP C
User's Guide for OpenVMS Systems

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Index

Your code may execute faster if it contains float variables and is compiled with /PRECISION=SINGLE. However, the results of your floating-point operations will be less precise. See the HP C Language Reference Manual for more information on floating-point variables.

The default is /PRECISION=DOUBLE for /STANDARD=VAXC and /STANDARD=COMMON compiler modes.

The default is /PRECISION=SINGLE for /STANDARD=ANSI89 and /STANDARD=RELAXED compiler modes.

/[NO]PREFIX_LIBRARY_ENTRIES[=(option[,...])]

The HP C Run-Time Library (RTL) shareable image, DECC$SHR.EXE, resides in SYS$LIBRARY with a DECC$ prefix for its entry points. The linker searches IMAGELIB.OLB to locate the shareable image. Every external name in IMAGELIB.OLB has a DECC$ prefix, and, therefore, has an OpenVMS conformant name space (a requirement for inclusion in IMAGELIB).

The /[NO]PREFIX_LIBRARY_ENTRIES qualifier lets you control the HP C RTL name prefixing. Table 1-20 describes the /PREFIX_LIBRARY_ENTRIES qualifier options.

Table 1-20 /PREFIX_LIBRARY_ENTRIES Qualifier Options
Option Usage

EXCEPT = ( name,...) The names specified are not prefixed.

ALL_ENTRIES All HP C RTL names, as well as C99 names not supported by the underlying C RTL, are prefixed.

ANSI_C89_ENTRIES Only C Standard 89 (C89) library names are prefixed.

C99_ENTRIES Only C Standard 99 (C99) library names are prefixed. These are a superset of the external names prefixed under /PREFIX=ANSI_C89_ENTRIES and a subset of those prefixed under /PREFIX=ALL_ENTRIES.
The compiler will prefix C99 entries based on their inclusion in the standard, not on the availability of their implementations in the run-time library. So calling functions introduced in C99 that are not yet implemented in the HP C RTL will produce unresolved references to symbols prefixed by DECC$ when the program is linked. In addition, the compiler will issue a CC-W-NOTINCRTL message when it prefixes a name that is not in the current C RTL.

RTL=" name" Generates references to the C RTL indicated by the name keyword. (The name keyword has a length limit of 24 characters for OpenVMS VAX systems and 1017 characters for OpenVMS Alpha systems.) If no keyword is specified, then references to the HP C RTL are generated by default. To use an alternate RTL, see its documentation for the name to use.

If you want no names prefixed, specify /NOPREFIX_LIBRARY_ENTRIES.

For /STANDARD=ANSI89, the default is /PREFIX=ANSI_C89_ENTRIES.

For /STANDARD=C99, the default is /PREFIX=C99_ENTRIES.

For all other compiler modes, the default is /PREFIX=ALL.

/[NO]PREPROCESS_ONLY[=filename]

Gives the same functionality as the -E qualifier on UNIX C compilers. When specified, it performs only the actions of the preprocessor phase and writes the resulting processed text to a file. No semantic or syntax processing is done. Furthermore, no object file or analysis file can be produced.

If you do not specify a file name for the preprocessor output, the name of the output file defaults to the file name of the input file with a .I file type.

The default is /NOPREPROCESS_ONLY.

/[NO]PROTOTYPE[=(option[,...])]

Creates an output file containing function prototypes for all global functions defined in the module being compiled.

Standard-style prototypes are created even for functions defined with Kernighan and Ritchie style syntax.

This qualifier can be used to convert to Standard-sytle prototypes or just to ensure that every function definition has a compatible explicit declaration, thereby avoiding implicit declarations that can sometimes produce surprising results.

Table 1-21 describes the /PROTOTYPE qualifier options.

Table 1-21 /PROTOTYPE Qualifier Options
Option Usage

[NO]IDENTIFIERS Indicates that identifier names are to be included in the prototype declarations that appear in the output file. The default is NOIDENTIFIERS.

[NO]STATIC_FUNCTIONS Indicates that prototypes for static function definitions are to be included in the output file. The default is NOSTATIC_FUNCTIONS.

FILE= filename Specifies the output file name. When not specified, the output file name has the same defaults as the listing file, except that the file extension is .CH instead of .LIS.

The default is /NOPROTOTYPES.

/PSECT_MODEL=[NO]MULTILANGUAGE

Controls whether the compiler allocates the size of overlaid psects to ensure compatibility when the psect is shared by code created by other HP compilers.

The problem this switch solves can occur when a psect generated by a FORTRAN COMMON block is overlaid with a psect consisting of a C struct. Because FORTRAN COMMON blocks are not padded, if the C struct is padded, the inconsistent psect sizes can cause linker error messages.

Compiling with /PSECT_MODEL=MULTILANGUAGE ensures that HP C uses a consistent psect size allocation scheme. The corresponding FORTRAN switch is /ALIGN=COMMON=[NO]MULTILANGUAGE.

The default is /PSECT=NOMULTILANGUAGE, which is the old default behavior of the compiler, and is sufficient for most applications.

/REENTRANCY=option

Controls the type of reentrancy that reentrant HP C RTL routines will exhibit. (See the decc$set_reentrancy RTL routine.)

This qualifier is for use only with a module containing the main routine.

The reentrancy level is set at runtime according to the /REENTRANCY qualifier specified while compiling the module containing the main routine.

Table 1-22 describes the /REENTRANCY qualifier options.

Table 1-22 /REENTRANCY Qualifier Options
Option Usage

AST Uses the __TESTBITSSI built-in function to perform simple locking around critical sections of RTL code, and may additionally disable asynchronous system traps (ASTs) in locked region of codes. This type of locking should be used when AST code contains calls to HP C RTL I/O routines.

MULTITHREAD Designed to be used in conjunction with the DECthreads product. It performs DECthreads locking and never disables ASTs.

NONE Gives optimal performance in the RTL, but does absolutely no locking around critical sections of RTL code. It should only be used in a single threaded environment when there is no chance that the thread of execution will be interrupted by an AST that would call the HP C RTL.

TOLERANT Uses the __TESTBITSSI built-in function to perform simple locking around critical sections of RTL code, but ASTs are not disabled. This type of locking should be used when ASTs are used and must be delivered immediately.

The default is /REENTRANCY=TOLERANT.

/REPOSITORY=option

Specifies a repository for the compiler to store shortened external name information. When /NAMES=SHORTENED is specified, the compiler stores to the repository any external names that were shortened. The demangler utility can then be used to map the shortened names back to the names used in the original C program.

By default, the qualifier is not active unless /NAMES=SHORTENED has been specified, in which case the default is /REPOSITORY=[.CXX_REPOSITORY].

The default name of the repository is the same as that used by the HP C++ compiler for decoding mangled names. This is intentional. A C++ mangled name cannot match a shortened name, so a single repository can be used by both the HP C and HP C++ compilers.

/ROUNDING_MODE=option

If /FLOAT=IEEE_MODE is specified, the /ROUNDING_MODE qualifier lets you select one of the following IEEE rounding modes:

Option	Usage
NEAREST	Sets the normal rounding mode (unbiased round to nearest). This is the default.
DYNAMIC	Sets the rounding mode for IEEE floating-point instructions dynamically, as determined from the contents of the floating-point control register.
MINUS_INFINITY	Rounds toward minus infinity.
CHOPPED	Rounds toward 0.

If /FLOAT=G_FLOAT or /FLOAT=D_FLOAT is specified, then rounding defaults to /ROUNDING_MODE=NEAREST, with no other choice of rounding mode.

/[NO]SHARE_GLOBALS

Controls whether the compiler will treat declarations of objects with the globaldef keyword as shared or not shared.

Also, in conjunction with the /EXTERN_MODEL qualifier, controls whether the initial extern_model is shared or not shared (for those extern_model s where it is allowed). The initial extern_model of the compiler is a fictitious pragma constructed from the settings of the /EXTERN_MODEL and /SHARE_GLOBALS qualifiers.

The default value is /NOSHARE_GLOBALS. This default value is different from VAX C, which treats external objects as shared by default. As a result, you may experience the following impact:

Linking old object files or object libraries with newly produced object files might generate "conflicting attributes for psect" messages. As long as you are not building shareable libraries, you can safely ignore these messages.
Building shareable libraries will be easier.
On OpenVMS VAX systems, when linking external symbols against FORTRAN common blocks, you should specify /SHARE_GLOBALS to suppress "conflicting attributes for psect" messages; although they can otherwise be ignored. (VAX ONLY)

/SHOW[=(option[,...])]

Sets or cancels listing options. You must use the /LIST qualifier with the /SHOW qualifier to use any of the /SHOW options. Table 1-23 describes the /SHOW qualifier options.

Table 1-23 /SHOW Qualifier Options
Option Usage

ALL Prints all listing information.

[NO]BRIEF Creates the same listing as the option SYMBOLS except that BRIEF eliminates from the list any identifiers that are not referenced in the program, and are not members of a structure or union that is referenced in the program.
The NOBRIEF option is the default.

[NO]CROSS_REFERENCE Specifies whether the compiler generates cross-references. If you specify /SHOW=CROSS_REFERENCE, the compiler lists, for each variable referenced in the procedure, the line numbers of the lines on which the variable is referenced.
You may use /SHOW=CROSS_REFERENCE with /SHOW=SYMBOLS. Otherwise, specifying /SHOW=CROSS_REFERENCE also gives you /SHOW=BRIEF. To obtain any type of listing, you must specify /LIST. Specifying /SHOW=[NO]CROSS_REFERENCE is the same as specifying /[NO]CROSS_REFERENCE.
The NOCROSS_REFERENCE option is the default.

[NO]DICTIONARY Places CDD/Repository definitions---included in the program with the #pragma dictionary preprocessor directive---into the listing file. These data definitions are marked in the listing file with an uppercase letter D in the listing margin.
The NODICTIONARY option is the default.

[NO]EXPANSION Places final macro expansions in the program listing. However, expansion text for preprocessing directives is not shown. When you specify this option, the number printed in the margin indicates the maximum depth of macro substitutions that occur on each line.
The NOEXPANSION option is the default.

[NO]HEADER Produces the header lines at the top of each page of a listing.
The HEADER option is the default.

[NO]INCLUDE Places the contents of #include files and modules in the program listing.
The NOINCLUDE option is the default.

[NO]INTERMEDIATE (VAX ONLY) Places all intermediate and final macro expansions in the program listing.
The NOINTERMEDIATE option is the default.

[NO]MESSAGES Lists all messages that are in effect at compilation (based on the settings of /STANDARD, /WARNINGS, and #pragma message).
The NOMESSAGE option is the default.

NONE Creates an empty listing file with only the header. If you specify this option on a CC command line that contains /LIST and /MACHINE_CODE, the compiler places machine code in the listing file.

[NO]SOURCE Places the source program statements in the program listing.
The SOURCE option is the default.

[NO]STATISTICS Places compiler performance statistics in the program listing.
The NOSTATISTICS option is the default.

[NO]SYMBOLS Places the symbol table of the compiled program in the program listing. The symbol table includes a list of all functions, the sizes and attributes of all variables referenced in the program, and a program section summary and function definition map.
The NOSYMBOLS option is the default.

[NO]TERMINAL (VAX ONLY) Displays compiler messages to the terminal. Use /SHOW=NOTERMINAL to suppress compiler messages to the terminal or to a batch log file.
The TERMINAL option is the default.

[NO]TRANSLATION (VAX ONLY) Places into the listing file all UNIX system file specifications that the compiler translates to OpenVMS file specifications. See the HP C Run-Time Library Reference Manual for OpenVMS Systems for more information on file translation.
The NOTRANSLATION option is the default.

/[NO]STANDARD[=(option[,...])]

Defines the compilation mode, directing the compiler to flag certain HP C-specific constructs and HP C relaxations of conventional C language constructs and rules. For example, the conversions from pointer to integer and back again are subject to more stringent tests when you specify /STANDARD=ANSI89.

Table 1-24 describes the /STANDARD qualifier options.

Table 1-24 /STANDARD Qualifier Options
Option Usage

ANSI89 Places the compiler in strict C Standard mode.

C99 Places the compiler in strict ISO/IEC C99 Standard mode. Note that /STANDARD=C99 is not fully supported on VAX systems. Specifying /STANDARD=C99 on OpenVMS VAX systems produces a warning and puts the compiler into /STANDARD=RELAXED mode.

LATEST Places the compiler in the latest ISO C standard dialect. /STANDARD=LATEST is currently equivalent to /STANDARD=C99, but is subject to change when newer versions of the ISO C standard are released.

RELAXED Places the compiler in relaxed C Standard mode.

MS Interprets source programs according to certain language rules followed by Microsoft's Visual C++ compiler.

ISOC94 Places the compiler in ISO C 94 mode, which enables digraph processing and defines the macro __STDC_VERSION__=199409L .
Digraphs are pairs of characters that translate into a single character, much like trigraphs, except that trigraphs get replaced inside string literals, but digraphs do not. The digraphs are:

Digraph Character Represented

<: [

:> ]

<% {

%> }

%: #

%:%: ##

The ISOC94 option can be specified alone or in combination with any other option except VAXC. If specified alone, ISOC94 provides a default major mode of RELAXED.

COMMON Places the compiler in common C mode. This mode enforces K & R programming style; that is, compatibility with older UNIX compilers such as pcc and gcc .

VAXC Places the compiler in VAX C mode.

PORTABLE Places the compiler in RELAXED mode, and enables the issuance of diagnostics that warn about any nonportable usages encountered.
/STANDARD=PORTABLE is supported for VAX C compatibility only. It is equivalent to the recommended combination of qualifiers /STANDARD= RELAXED/WARNINGS=ENABLE=PORTABLE.

MIA Places the compiler in strict C Standard mode with some behavior differences, as required by the MIA standard:

On OpenVMS VAX systems, G_floating becomes the default floating-point format for double variables. (VAX ONLY)
On OpenVMS Alpha systems, G_floating is the default in any case. (ALPHA ONLY)
In structures, zero-length bit fields cause the next bit field to start on an integer boundary, rather than on a character boundary.

Compiling a program with /STANDARD=MIA sets the __MIA predefined macro to 1.

The default is /NOSTANDARD, which is equivalent to /STANDARD=RELAXED.

If you specify /STANDARD, you must supply at least one option.

With one exception, the /STANDARD qualifier options are mutually exclusive. Do not combine them. The exception is that you can specify /STANDARD=ISOC94 with any other option except VAXC.

HP C modules compiled in different modes can be linked and executed together.

Also see the __HIDE_FORBIDDEN_NAMES predefined macro ( Section 6.1.7).

/[NO]TIE

Enables the compiled code to be used in combination with translated images, either because the code might call into a translated image or might be called from a translated image. The default is /NOTIE.

/[NO]UNDEFINE=(identifier[,...])

See /[NO]DEFINE in this section.

/[NO]UNSIGNED_CHAR

By default, char is a signed character type. The /UNSIGNED_CHAR qualifier lets you change this default to an unsigned character type, which causes all plain char declarations to have the same representation and set of values as unsigned char declarations. The default is /NOUNSIGNED_CHAR.

/VAXC (VAX ONLY)

Invokes the VAX C compiler.

The CC command is used to invoke either the VAX C or HP C compiler. If your system has a VAX C compiler installed on it, the HP C installation procedure provides the option of specifying which compiler will be invoked by default when just the CC command is used. To invoke the compiler that is not the default, use the CC command with the appropriate qualifier: CC/DECC for the HP C compiler, or CC/VAXC for the VAX C compiler.

If your system does not have a VAX C compiler installed on it, the CC command will invoke the HP C compiler, and the /VAXC qualifier is not supported.

/[NO]VERSION

Directs the compiler to print out the compiler version and platform. The compiler version is the same as in the listing file.

This qualifier makes it easier for you to report what compiler you are using.

Note

To display the compiler version and platform when issuing the CC command for a source file that does not exist, enter:

CC/DECC/VERSION NL:

/[NO]WARNINGS[=(option[,...])]

Controls the issuance of compiler diagnostic messages or groups of messages. It also allows for the severity of messages to be modified. The default qualifier, /WARNINGS, enables all warning and informational messages for the compiler mode you are using. The /NOWARNINGS qualifier suppresses the warning and informational messages. Also see the #pragma message preprocessor directive.

Table 1-25 describes the /WARNING qualifier options.

For a description of what to specify for the message-list, see the #pragma message preprocessor directive ( Section 5.4.14).

Table 1-25 /WARNINGS Qualifier Options
Option Usage

DISABLE= message-list Suppresses the issuance of the specified messages.
Only messages of severity Warning (W) or Information (I) can be disabled. If the message has severity of Error (E) or Fatal (F), it is issued regardless of any attempt to disable it.

ENABLE= message-list Enables issuance of the specified messages.

NOINFORMATIONALS Suppresses informational messages.

EMIT_ONCE= message-list Emits the specified messages only once per compilation.
Certain messages are emitted only the first time the compiler encounters the causal condition. When the compiler encounters the same condition later in the program, no message is emitted. Messages about the use of language extensions are an example of this kind of message. To emit one of these messages every time the causal condition is encountered, use the EMIT_ALWAYS option.
Errors and Fatals are always emitted. You cannot set them to EMIT_ONCE.

EMIT_ALWAYS= message-list Emits the specified messages at every occurrence of the causal condition.

ERRORS= message-list Sets the severity of the specified messages to Error.
Supplied Error messages and Fatal messages cannot be made less severe. (Exception: A message can be upgraded from Error to Fatal, then later downgraded to Error again, but it can never be downgraded from Error.)
Warnings and Informationals can be made any severity.

FATALS= message-list Sets the severity of the specified messages to Fatal.

INFORMATIONALS= message-list Sets the severity of the specified messages to Informational. Note that Fatal and Error messages cannot be made less severe.

WARNINGS= message-list Sets the severity of the specified messages to Warning. Note that Fatal and Error messages cannot be made less severe.

VERBOSE Displays the full message information for every compiler message encountered. This information includes the message description and user action, as well as the identifier, severity, and message text.
When /WARNINGS=VERBOSE is used with /LIST/SHOW=MESSAGES, a list of all messages in effect at compilation are added to the listing file, showing the full information for each message.

Notes

If a message is on both the enabled and disabled list, it is disabled.
If a message is on both the EMIT_ONCE and the EMIT_ALWAYS list, it is considered to be on the EMIT_ONCE list.
If a message is on more than one of the FATALS, ERRORS, WARNINGS, or INFORMATIONALS lists, the message is given the least severe level.
The NOINFORMATIONALS option is not the negation of INFORMATIONALS=msg-list. It is valid to specify:
/WARNINGS=(INFORMATIONALS=message_list,NOINFORMATIONALS)
This has the effect of making the messages on the message_list informationals, and causing the compiler to suppress any informational messages.
One of the message groups described in the #pragma message description in Section 5.4.14 is UNUSED, which enables messages that report apparently unnecessary #include files and CDD records.

However, unlike any other messages, these messages must be enabled on the command line (/WARNINGS=ENABLE=UNUSED) to be effective. Any #pragma message directives within the source have no effect on these messages; their state is determined only by processing the command line.