A scalar data type holds a single value, such as the integer value 42 or the real value 112.6. The next table lists Fortran scalar data types, their size, format and range. Table 3 shows the range and approximate precision for Fortran real data types. Table 4 shows the alignment for different scalar data types. The alignments apply to all scalars, whether they are independent or contained in an array, a structure or a union.

⁽¹⁾ Approximate value

The logical constants .TRUE. and .FALSE. are all ones and all zeroes, respectively. Internally, the value of a logical variable is true if the least significant bit is one and false otherwise. When the option -⁠Munixlogical is set, a logical variable with a non-zero value is true and with a zero value is false.

The NVFORTRAN compiler supports real(2) data type which makes it possible to declare and use data in half precision floating point. It is explicitly required to use the kind attribute with value of 2 on real data type to take advantage of this support. The following operators are supported for this data type: + , -, *, /, .lt., .le., .gt., .ge., .eq.,.ne..

There are several ways to create real(2) constants:

  ! Using kind attribute of 2 by appending _2 to the floating point value:
  real(2) :: val1 = 2.0_2
  ! Using a hexadecimal constant:
  real(2) :: val2 = z'4000'
  ! Explicitly calling real() intrinsic with the value to be converted:
  real(2) :: val3 = real(2, kind=2)
  ! Implicitly relying on compiler to convert value to real(2):
  real(2) :: val4 = 2d0
    

Half precision native support is not available on all of the architecture targets that NVFORTRAN supports. It is still possible to use this type, but be aware that implementation relies on conversion to real(4), handling operation in real(4), and then converting back to real(2). NVIDIA GPUs which support CUDA Compute Capability 6.0 and above implement operations natively and do not rely on conversion.

Half precision is represented as IEEE 754 binary16. Out of the 16-bits available to represent the floating point value, one bit is used for sign, five bits are used for exponent, and ten bits are used for significand. When encountering values that cannot be precisely represented in the format, such as when adding two real(2) numbers, IEEE 754 defines rounding rules. In the case of real(2), the default rule is round-to-nearest with ties-to-even property which is described in detail in the IEEE 754-2008 standard in section 4.3.1. This format has a small dynamic range and thus values greater than 65520 are rounded to infinity.

The NVFORTRAN compiler supports de facto standard extensions to FORTRAN 77 that allow for aggregate data types. An aggregate data type consists of one or more scalar data type objects. You can declare the following aggregate data types:

• An array consists of one or more elements of a single data type placed in contiguous locations from first to last.
• A structure can contain different data types. The members are allocated in the order they appear in the definition but may not occupy contiguous locations.
• A union is a single location that can contain any of a specified set of scalar or aggregate data types. A union can have only one value at a time. The data type of the union member to which data is assigned determines the data type of the union after that assignment.

The alignment of an array, a structure or union (an aggregate) affects how much space the object occupies and how efficiently the processor can address members. Arrays use the alignment of their members.

Array types

align according to the alignment of the array elements. For example, an array of INTEGER*2 data aligns on a 2-byte boundary. The exception to this rule is that aligment of REAL*2 arrays is on a 4-byte boundary.

Structures and Unions

align according to the alignment of the most restricted data type of the structure or union. In the next example, the union aligns on a 4-byte boundary since the alignment of c, the most restrictive element, is four.

STRUCTURE /astr/
UNION
 MAP
 INTEGER*2 a ! 2 bytes
 END MAP
 MAP
 BYTE b ! 1 byte
 END MAP
 MAP
 INTEGER*4 c ! 4 bytes
 END MAP
END UNION
END STRUCTURE

Structure alignment can result in unused space called padding. Padding between members of the structure is called internal padding. Padding between the last member and the end of the space is called tail padding.

The offset of a structure member from the beginning of the structure is a multiple of the member's alignment. For example, since an INTEGER*2 aligns on a 2-byte boundary, the offset of an INTEGER*2 member from the beginning of a structure is a multiple of two bytes.

The Fortran 90 standard added formal support for aggregate data types. The TYPE statement begins a derived type data specification or declares variables of a specified user-defined type. For example, the following would define a derived type ATTENDEE:

TYPE ATTENDEE
 CHARACTER(LEN=30) NAME
 CHARACTER(LEN=30) ORGANIZATION
 CHARACTER (LEN=30) EMAIL
END TYPE ATTENDEE

In order to declare a variable of type ATTENDEE and access the contents of such a variable, code such as the following would be used:

TYPE (ATTENDEE) ATTLIST(100)
. . .
ATTLIST(1)%NAME = ‘JOHN DOE’

Table 5 lists C and C++ scalar data types, providing their size and format. The alignment of a scalar data type is equal to its size. Table 6 shows scalar alignments that apply to individual scalars and to scalars that are elements of an array or members of a structure or union. Wide characters are supported (character constants prefixed with an L). The size of each wide character is 4 bytes.

⁽¹⁾ Approximate value

⁽²⁾ Bit fields occupy as many bits as you assign them, up to 4 bytes, and their length need not be a multiple of 8 bits (1 byte)

An aggregate data type consists of one or more scalar data type objects. You can declare the following aggregate data types:

array

consists of one or more elements of a single data type placed in contiguous locations from first to last.

class

(C++ only) is a class that defines an object and its member functions. The object can contain fundamental data types or other aggregates including other classes. The class members are allocated in the order they appear in the definition but may not occupy contiguous locations.

struct

is a structure that can contain different data types. The members are allocated in the order they appear in the definition but may not occupy contiguous locations. When a struct is defined with member functions, its alignment rules are the same as those for a class.

union

is a single location that can contain any of a specified set of scalar or aggregate data types. A union can have only one value at a time. The data type of the union member to which data is assigned determines the data type of the union after that assignment.

Class and structure objects with no virtual entities and with no base classes, that is just direct data field members, are laid out in the same manner as C structures. The following section describes the alignment and size of these C-like structures. C++ classes (and structures as a special case of a class) are more difficult to describe. Their alignment and size is determined by compiler generated fields in addition to user-specified fields. The following paragraphs describe how storage is laid out for more general classes. The user is warned that the alignment and size of a class (or structure) is dependent on the existence and placement of direct and virtual base classes and of virtual function information. The information that follows is for informational purposes only, reflects the current implementation, and is subject to change. Do not make assumptions about the layout of complex classes or structures.

All classes are laid out in the same general way, using the following pattern (in the sequence indicated):

• First, storage for all of the direct base classes (which implicitly includes storage for non-virtual indirect base classes as well):
  • When the direct base class is also virtual, only enough space is set aside for a pointer to the actual storage, which appears later.
  • In the case of a non-virtual direct base class, enough storage is set aside for its own non-virtual base classes, its virtual base class pointers, its own fields, and its virtual function information, but no space is allocated for its virtual base classes.
• Next, storage for the class’s own fields.
• Next, storage for virtual function information (typically, a pointer to a virtual function table).
• Finally, storage for its virtual base classes, with space enough in each case for its own non-virtual base classes, virtual base class pointers, fields, and virtual function information.

The alignment of an array, a structure or union (an aggregate) affects how much space the object occupies and how efficiently the processor can address members.

Arrays

align according to the alignment of the array elements. For example, an array of short data type aligns on a 2-byte boundary.

Structures and Unions

align according to the most restrictive alignment of the enclosing members. In the following example, the union un1 aligns on a 4-byte boundary since the alignment of c, the most restrictive element, is four:

union un1 {
 short a; /* 2 bytes */
 char b; /* 1 byte */
 int c; /* 4 bytes */
 };

Structure alignment can result in unused space, called padding. Padding between members of a structure is called internal padding. Padding between the last member and the end of the space occupied by the structure is called tail padding. Figure 1 illustrates structure alignment. Consider the following structure:

struct strc1 {
 char a; /* occupies byte 0 */
 short b; /* occupies bytes 2 and 3 */
 char c; /* occupies byte 4 */
 int d; /* occupies bytes 8 through 11 */
 };

Figure 1. Internal Padding in a Structure

Figure 2 shows how tail padding is applied to a structure aligned on a doubleword (8 byte) boundary.

struct strc2{
 int m1[4]; /* occupies bytes
0 through 15 */
 double m2; /* occupies bytes 16 through 23 */
 short m3; /* occupies bytes 24 and 25 */
} st;

Bit-fields have the same size and alignment rules as other aggregates, with several additions to these rules:

• Bit-fields are allocated from right to left.
• A bit-field must entirely reside in a storage unit appropriate for its type. Bit-fields never cross unit boundaries.
• Bit-fields may share a storage unit with other structure/union members, including members that are not bit-fields.
• Unnamed bit-field's types do not affect the alignment of a structure or union.

Figure 2. Tail Padding in a Structure

The void data type is neither a scalar nor an aggregate. You can use void or void* as the return type of a function to indicate the function does not return a value, or as a pointer to an unspecified data type, respectively.

The const and volatile type qualifiers do not in themselves define data types, but associate attributes with other types. Use const to specify that an identifier is a constant and is not to be changed. Use volatile to prevent optimization problems with data that can be changed from outside the program, such as memory-mapped I/O buffers.

Extended integer types __int128 and unsigned __int128 are now supported by NVC and NVC++. 128-bit integer support can be turned on with the -Mint128 flag. Note, 128-bit integer support is not supported with OpenMP, OpenACC and CUDA.

The options included in the following table pertain to optimizing your program or application code.

The options included in the following table pertain to the initial building of your program or application.

The options included in the following table pertain to debugging your program or application.

The options included in the following table pertain to defining parameters related to linking and running your program or application.

This section describes the -⁠M<nvflag> options that control code generation.

Default: For arguments that you do not specify, the default code generation controls are these:

Related options:-⁠D, -⁠I, -⁠L, -⁠l, -⁠U.

The following list provides the syntax for each -⁠M<nvflag> option that controls code generation. Each option has a description and, if appropriate, any related options.

-Mdaz

Set IEEE denormalized floating point operands to zero; there is a performance benefit but misleading results can occur, such as when dividing a small normalized number by a denormalized number. To take effect, this option must be set when compiling the main program/function. [default - x86_64 and aarch64; does not apply to ppc64le]

Note: Same functionality can be achieved with the runtime environment variable NVCOMPILER_FPU_STATE

-Mnodaz

Do not treat denormalized numbers as zero. To take effect, this option must be set for the main program.

Note: Same functionality can be achieved with the runtime environment variable NVCOMPILER_FPU_STATE

-Mnodwarf

Specifies not to add DWARF debug information.

-Mdwarf2

Generate DWARF2 format debug information. To take effect, this option must be used in combination with -⁠g.

-Mdwarf3

Generate DWARF3 format debug information. To take effect, this option must be used in combination with -⁠g.

-Mflushz

Set floating point control register to flush-to-zero mode; if a floating-point underflow occurs, the result is set to zero. To take effect, this option must be set when compiling the main program/function. [default - x86_64 and aarch64; does not apply to ppc64le]

Note: Same functionality can be achieved with the runtime environment variable NVCOMPILER_FPU_STATE

-Mnoflushz

Do not set flush-to-zero mode; generate underflows. To take effect, this option must be set for the main program.

Note: Same functionality can be achieved with the runtime environment variable NVCOMPILER_FPU_STATE

-Mfunc32

Align functions on 32-byte boundaries.

-Minstrument[=functions]

Generate additional code to enable instrumentation of functions. The option -⁠Minstrument=functions is the same as -⁠Minstrument. Implies -⁠Mframe.

-Mlarge_arrays

Enable support for 64-bit indexing and single static data objects larger than 2 GB in size. This option is the default in the presence of -⁠mcmodel=medium. It can be used separately together with the default small memory model for certain 64-bit applications that manage their own memory space. For more information, refer to the ‘Programming Considerations for 64-Bit Environments’ section of the HPC Compilers User Guide

-Mnolarge_arrays

Disable support for 64-bit indexing and single static data objects larger than 2 GB in size. When this option is placed after -⁠mcmodel=medium on the command line, it disables use of 64-bit indexing for applications that have no single data object larger than 2 GB. For more information, refer to the ‘Programming Considerations for 64-Bit Environments’ section of the HPC Compilers User Guide.

-Mnomain

Instructs the compiler not to include the object file that calls the Fortran main program as part of the link step. This option is useful for linking programs in which the main program is written in C/C++ and one or more subroutines are written in Fortran (Fortran only).

-M[no]pre

enables [disables] partial redundancy elimination.

-Mrecursive

instructs the compiler to allow Fortran subprograms to be called recursively.

-Mnorecursive

Fortran subprograms may not be called recursively.

-Mref_externals

force references to names appearing in EXTERNAL statements (Fortran only).

-Mnoref_externals

do not force references to names appearing in EXTERNAL statements (Fortran only).

-Mreentrant

instructs the compiler to avoid optimizations that can prevent code from being reentrant.

-Mnoreentrant

instructs the compiler not to avoid optimizations that can prevent code from being reentrant.

-Msecond_underscore

instructs the compiler to add a second underscore to the name of a Fortran global symbol if its name already contains an underscore. This option is useful for maintaining compatibility with object code compiled using gfortran, which uses this convention by default (Fortran only).

-Mnosecond_underscore

instructs the compiler not to add a second underscore to the name of a Fortran global symbol if its name already contains an underscore (Fortran only).

-Msafe_lastval

When a scalar is used after a loop, but is not defined on every iteration of the loop, the compiler does not by default parallelize the loop. However, this option tells the compiler it’s safe to parallelize the loop. For a given loop, the last value computed for all scalars makes it safe to parallelize the loop.

-Msignextend

instructs the compiler to extend the sign bit that is set as a result of converting an object of one data type to an object of a larger signed data type.

-Mnosignextend

instructs the compiler not to extend the sign bit that is set as the result of converting an object of one data type to an object of a larger data type.

-Mstack_arrays

places automatic arrays on the stack.

-Mnostack_arrays

allocates automatic arrays on the heap. -Mnostack_arrays is the default and what traditionally has been the approach used.

-Mstride0

instructs the compiler to inhibit certain optimizations and to allow for stride 0 array references. This option may degrade performance and should only be used if zero-stride induction variables are possible.

-Mnostride0

instructs the compiler to perform certain optimizations and to disallow for stride 0 array references.

-Mvarargs

force Fortran program units to assume procedure calls are to C functions with a varargs-type interface (nvfortran only).

This section describes the -⁠M<nvflag> options that affect C++ and C language interpretations by the NVC++ and NVC compilers. These options are only valid to the nvc++ and nvc compiler drivers.

Default: For arguments that you do not specify, the defaults are as follows:

Usage:

In this example, the compiler allows the asm keyword in the source file.

	$ nvc -Masmkeyword myprog.c

In the following example, the compiler maps the dollar sign to the dot character.

	$ nvc -Mdollar,. myprog.c

In the following example, the compiler treats floating-point constants as float values, rather than the default double.

	$ nvc -Mfcon myprog.c

In the following example, the compiler does not convert float parameters to double parameters.

	$ nvc -Msingle myprog.c

Without -⁠Muchar or with -⁠Mschar, the variable ch is a signed character:

	char ch;
	signed char sch;

If -⁠Muchar is specified on the command line:

	$ nvc -Muchar myprog.c

char ch in the preceding declaration is equivalent to:

 unsigned char ch;

The following list provides the syntax for each -⁠M<nvflag> option that controls code generation in C++ and C. Each option has a description and, if appropriate, any related options.

-Masmkeyword

instructs the compiler to allow the asm keyword in C source files. The syntax of the asm statement is as follows:

asm("statement");

Where statement is a legal assembly-language statement. The quote marks are required.

Note: The current default is to support gcc's extended asm, where the syntax of extended asm includes asm strings. The -⁠M[no]asmkeyword switch is useful only if the target device is a Pentium 3 or older cpu type (-⁠tp piii|p6|k7|athlon|athlonxp|px).

-Mnoasmkeyword

instructs the compiler not to allow the asm keyword in C source files. If you use this option and your program includes the asm keyword, unresolved references are generated

-Mdollar,char

char specifies the character to which the compiler maps the dollar sign ($). The NVC compiler allows the dollar sign in names; ANSI C does not allow the dollar sign in names.

-M[no]eh_frame

instructs the linker to keep eh_frame call frame sections in the executable.

Note: The eh_frame option is available only on newer Linux systems that supply the system unwind libraries.

-Mfcon

instructs the compiler to treat floating-point constants as float data types, instead of double data types. This option can improve the performance of single-precision code.

-M[no]m128

instructs the compiler to recognize [ignore] __m128, __m128d, and __m128i datatypes.

-Mschar

specifies signed char characters. The compiler treats "plain" char declarations as signed char.

-Msingle

do not to convert float parameters to double parameters in non-prototyped functions. This option can result in faster code if your program uses only float parameters. However, since ANSI C specifies that routines must convert float parameters to double parameters in non-prototyped functions, this option results in non-ANSI conformant code.

-Mnosingle

instructs the compiler to convert float parameters to double parameters in non-prototyped functions.

-Muchar

instructs the compiler to treat "plain" char declarations as unsigned char.

This section describes the -⁠M<nvflag> options that control environments.

Default: For arguments that you do not specify, the default environment option depends on your configuration.

The following list provides the syntax for each -⁠M<nvflag> option that controls environments. Each option has a description and, if appropriate, a list of any related options.

-Mnostartup

instructs the linker not to link in the standard startup routine that contains the entry point (_start) for the program.

Note: If you use the -⁠Mnostartup option and do not supply an entry point, the linker issues the following error message: Warning: cannot find entry symbol _start

-M[no]hugetlb

links in the huge page runtime library. Enables large 2-megabyte pages to be allocated. The effect is to reduce the number of TLB entries required to execute a program. This option is most effective on newer architectures; older architectures do not have enough TLB entries for this option to be beneficial. By itself, the huge suboption tries to allocate as many huge pages as required. You can also limit the pages allocated by using the environment variable NVCOMPILER_HUGE_PAGES.

-M[no]stddef

instructs the compiler not to predefine any macros to the preprocessor when compiling a C program.

-Mnostdinc

instructs the compiler to not search the standard location for include files.

-Mnostdlib

instructs the linker not to link in the standard libraries libnvf.a, libm.a, libc.a, and libnvc.a in the library directory lib within the standard directory. You can link in your own library with the -⁠l option or specify a library directory with the -⁠L option.

This section describes the -⁠M<nvflag> options that affect Fortran language interpretations by the NVIDIA Fortran compiler. These options are valid only for the nvfortran compiler driver.

Default: Before looking at all the options, let's look at the defaults. For arguments that you do not specify, the defaults are as follows:

The following list provides the syntax for each -⁠M<nvflag> option that affect Fortran language interpretations. Each option has a description and, if appropriate, a list of any related options.

-Mallocatable=95|03

controls whether Fortran 95 or Fortran 2003 semantics are used in allocatable array assignments. The default behavior is to use Fortran 95 semantics; the 03 option instructs the compiler to use Fortran 2003 semantics.

-Mbackslash

instructs the compiler to treat the backslash as a normal character, and not as an escape character in quoted strings.

-Mnobackslash

instructs the compiler to recognize a backslash as an escape character in quoted strings (in accordance with standard C usage).

-Mdclchk

instructs the compiler to require that all program variables be declared.

-Mnodclchk

instructs the compiler not to require that all program variables be declared.

-Mdefaultunit

instructs the compiler to treat "*" as a synonym for standard input for reading and standard output for writing.

-Mnodefaultunit

instructs the compiler to treat "*" as a synonym for unit 5 on input and unit 6 on output.

-Mdlines

instructs the compiler to treat lines containing "D" in column 1 as executable statements (ignoring the "D").

-Mnodlines

instructs the compiler not to treat lines containing "D" in column 1 as executable statements. The compiler does not ignore the "D".

-Mdollar,char

char specifies the character to which the compiler maps the dollar sign. The compiler allows the dollar sign in names.

-Mextend

instructs the compiler to accept 132-column source code; otherwise it accepts 72-column code.

-Mfixed

instructs the compiler to assume input source files are in FORTRAN 77-style fixed form format.

-Mfree

instructs the compiler to assume input source files are in Fortran 90/95 freeform format.

-Miomutex

instructs the compiler to generate critical section calls around Fortran I/O statements.

-Mnoiomutex

instructs the compiler not to generate critical section calls around Fortran I/O statements.

-Monetrip

instructs the compiler to force each DO loop to execute at least once. This option is useful for programs written for earlier versions of Fortran.

-Mnoonetrip

instructs the compiler not to force each DO loop to execute at least once.

-Msave

instructs the compiler to assume that all local variables are subject to the SAVE statement. This may allow older Fortran programs to run, but it can greatly reduce performance.

-Mnosave

instructs the compiler not to assume that all local variables are subject to the SAVE statement.

-Mstandard

instructs the compiler to flag non-ANSI-conforming source code.

-Munixlogical

directs the compiler to treat logical values as true if the value is non-zero and false if the value is zero (UNIX F77 convention). When -⁠Munixlogical is enabled, a logical value or test that is non-zero is .TRUE., and a value or test that is zero is .FALSE.. In addition, the value of a logical expression is guaranteed to be one (1) when the result is .TRUE..

-Mnounixlogical

directs the compiler to use the VMS convention for logical values for true and false. Even values are true and odd values are false.

-Mupcase

instructs the compiler to preserve uppercase letters in identifiers. With -⁠Mupcase, the identifiers "X" and "x" are different. Keywords must be in lower case. This selection affects the linking process. If you compile and link the same source code using -⁠Mupcase on one occasion and -⁠Mnoupcase on another, you may get two different executables – depending on whether the source contains uppercase letters. The standard libraries are compiled using the default -⁠Mnoupcase .

-Mnoupcase

instructs the compiler to convert all identifiers to lower case. This selection affects the linking process. If you compile and link the same source code using -⁠Mupcase on one occasion and -⁠Mnoupcase on another, you may get two different executables, depending on whether the source contains uppercase letters. The standard libraries are compiled using -⁠Mnoupcase.

This section describes the -⁠M<nvflag> options that control function inlining.

Usage: Before looking at all the options, let’s look at a few examples. In the following example, the compiler extracts functions that have 500 or fewer statements from the source file myprog.f and saves them in the file extract.il.

$ nvfortran -Mextract=500 -o extract.il myprog.f

In the following example, the compiler inlines functions with fewer than approximately 100 statements in the source file myprog.f.

$ nvfortran -Minline=maxsize:100 myprog.f

Related options: -⁠o, -⁠Mextract

The following list provides the syntax for each -⁠M<nvflag> option that controls function inlining. Each option has a description and, if appropriate, a list of any related options.

-M[no]autoinline[=option[,option,...]]

instructs the compiler to inline [not to inline] a C++ and C functions at -⁠O2, where the option can be any of these:

maxsize:n

instructs the compiler not to inline functions of size > n. The default size is 100.

nostatic

do not inline static functions without the inline keyword

totalsize:n

instructs the compiler to stop inlining when the size equals n. The default size is 800.

-Mextract[=option[,option,...]]

Extracts functions from the file indicated on the command line and creates or appends to the specified extract directory where option can be any of the following:

name:func

instructs the extractor to extract function func from the file.

size:number

instructs the extractor to extract functions with number or fewer statements from the file.

lib:filename.ext

instructs the extractor to use directory filename.ext as the extract directory, which is required to save and re-use inline libraries.

If you specify both name and size, the compiler extracts functions that match func, or that have number or fewer statements. For examples of extracting functions, refer to the ‘Using Function Inlining’ section of the HPC Compilers User Guide.

-Minline[=option[,option,...]]

instructs the compiler to pass options to the function inliner, where the option can be any of the following:

except:func

Inlines all eligible functions except func, a function in the source text. You can use a comma-separated list to specify multiple functions.

[name:]func

Inlines all functions in the source text whose name matches func. You can use a comma-separated list to specify multiple functions.

The function name should be a non-numeric string that does not contain a period. You can also use a name: prefix followed by the function name. If name: is specified, what follows is always the name of a function.

[maxsize:]number

A numeric option is assumed to be a size. Functions of size number or less are inlined. If both number and function are specified, then functions matching the given name(s) or meeting the size requirements are inlined.

The size number need not exactly equal the number of statements in a selected function; the size parameter is merely a rough gauge.

[no]reshape

instructs the inliner to allow [disallow] inlining in Fortran even when array shapes do not match. The default is -⁠Minline=noreshape, except with -⁠Mconcur or -⁠mp, where the default is -⁠Minline=reshape.

smallsize:number

Always inline functions of size smaller than number regardless of other size limits.

totalsize:number

Stop inlining in a function when the function's total inlined size reaches the number specified.

[lib:]filename.ext

instructs the inliner to inline the functions within the library file filename.ext. The compiler assumes that a filename.ext option containing a period is a library file.

Tip: Create the library file using the -⁠Mextract option. You can also use a lib: prefix followed by the library name.

• If lib: is specified, no period is necessary in the library name. Functions from the specified library are inlined.
• If no library is specified, functions are extracted from a temporary library created during an extract prepass.

If you specify both func and number, the compiler inlines functions that match the function name or have number or fewer statements.

Inlining can be disabled with -⁠Mnoinline.

For examples of inlining functions, refer to the ‘Using Function Inlining’ section of the HPC Compilers User Guide.

This section describes the -⁠M<nvflag> options that control optimization.

Default: Before looking at all the options, let's look at the defaults. For arguments that you do not specify, the default optimization control options are as follows:

Usage: In this example, the compiler invokes the vectorizer with use of packed SIMD instructions enabled.

$ nvfortran -Mvect=simd -Mcache_align myprog.f

Related options:-⁠g, -⁠O

The following list provides the syntax for each -⁠M<nvflag> option that controls optimization. Each option has a description and, if appropriate, a list of any related options.

-Mcache_align

Align unconstrained objects of length greater than or equal to 16 bytes on cache-line boundaries. An unconstrained object is a data object that is not a member of an aggregate structure or common block. This option does not affect the alignment of allocatable or automatic arrays. To effect cache-line alignment of stack-based local variables, the main program or function must be compiled with -⁠Mcache_align.

-Mconcur[=option [,option,...]]

Instructs the compiler to enable auto-parallelization of loops for multicore CPUs. If -⁠Mconcur is specified, multiple CPU cores will be used to execute loops that the compiler determines to be parallelizable. option is one of the following:

allcores

Instructs the compiler to use all available cores. Use this option at link time.

[no]altcode:n

Instructs the parallelizer to generate alternate serial code for parallelized loops.

• If altcode is specified without arguments, the parallelizer determines an appropriate cutoff length and generates serial code to be executed whenever the loop count is less than or equal to that length.
• If altcode:n is specified, the serial altcode is executed whenever the loop count is less than or equal to n.
• If noaltcode is specified, the parallelized version of the loop is always executed regardless of the loop count.

cncall

Indicates that calls in parallel loops are safe to parallelize. Also, no minimum loop count threshold must be satisfied before parallelization will occur, and last values of scalars are assumed to be safe.

[no]innermost

Instructs the parallelizer to enable parallelization of innermost loops. The default is to not parallelize innermost loops, since it is usually not profitable on dual-core processors.

levels:n

Parallelize loops nested at most n levels deep.

noassoc

Instructs the parallelizer to disable parallelization of loops with reductions.

When linking, the -⁠Mconcur switch must be specified or unresolved references result.

Note: This option applies only on shared-memory multi-processor (SMP) or multicore CPU-based systems.

-Mcray[=option[,option,...]]

(Fortran only) Force Cray Fortran compatibility with respect to the listed options. Possible values of option include:

pointer

for purposes of optimization, it is assumed that pointer-based variables do not overlay the storage of any other variable.

-Mdepchk

instructs the compiler to assume unresolved data dependencies actually conflict.

-Mnodepchk

Instructs the compiler to assume potential data dependencies do not conflict. However, if data dependencies exist, this option can produce incorrect code.

-Mdse

Enables a dead store elimination phase that is useful for programs that rely on extensive use of inline function calls for performance. This is disabled by default.

-Mnodse

Disables the dead store elimination phase. This is the default.

-M[no]fpapprox[=option]

Perform certain floating point operations using low-precision approximation. -⁠Mnofpapprox specifies not to use low-precision fp approximation operations. By default -⁠Mfpapprox is not used. If -⁠Mfpapprox is used without suboptions, it defaults to use approximate div, sqrt, and rsqrt. The available suboptions are these:

div

Approximate floating point division

sqrt

Approximate floating point square root

rsqrt

Approximate floating point reciprocal square root

-M[no]fpmisalign

Instructs the compiler to allow (not allow) vector arithmetic instructions with memory operands that are not aligned on 16-byte boundaries. The default is -⁠Mnofpmisalign on all processors.

-M[no]fprelaxed[=option]

Instructs the compiler to use [not use] relaxed precision in the calculation of some intrinsic functions. Can result in improved performance at the expense of numerical accuracy. The possible values for option are:

div

Perform divide using relaxed precision.

intrinsic

Enables use of relaxed precision intrinsics.

noorder

Do not allow expression reordering or factoring.

order

Allow expression reordering, including factoring.

recip

Perform reciprocal using relaxed precision.

rsqrt

Perform reciprocal square root (1/sqrt) using relaxed precision.

sqrt

Perform square root with relaxed precision.

With no options, -⁠Mfprelaxed generates relaxed precision code for those operations that generate a significant performance improvement, depending on the target processor. The default is -⁠Mnofprelaxed which instructs the compiler to not use relaxed precision in the calculation of intrinsic functions.

-Mi4

(Fortran only) instructs the compiler to treat INTEGER variables as INTEGER*4.

-Mlre[=array | assoc | noassoc]

Enables loop-carried redundancy elimination, an optimization that can reduce the number of arithmetic operations and memory references in loops. The available suboptions are:

assoc

allow expression re-association. Specifying this suboption can increase opportunities for loop-carried redundancy elimination but may alter numerical results.

noassoc

disallow expression re-association.

-Mnolre

Disable loop-carried redundancy elimination.

-Mnoframe

Eliminate operations that set up a true stack frame pointer for every function. With this option enabled, you cannot perform a traceback on the generated code and you cannot access local variables.

-Mnoi4

(Fortran only) instructs the compiler to treat INTEGER variables as INTEGER*2.

-Mpre

Enables partial redundancy elimination.

-Mprefetch[=option [,option...]]

enables generation of prefetch instructions on processors where they are supported. Possible values for option include:

d:m

set the fetch-ahead distance for prefetch instructions to m cache lines.

n:p

set the maximum number of prefetch instructions to generate for a given loop to p.

nta

use the prefetch instruction.

plain

use the prefetch instruction (default).

t0

use the prefetcht0 instruction.

w

use the AMD-specific prefetchw instruction.

-Mnoprefetch

Disables generation of prefetch instructions.

-M[no]propcond

Enables or disables constant propagation from assertions derived from equality conditionals. The default is enabled.

-Mr8

(Fortran only) The compiler promotes REAL variables and constants to DOUBLE PRECISION variables and constants, respectively. DOUBLE PRECISION elements are 8 bytes in length.

-Mnor8

(Fortran only) The compiler does not promote REAL variables and constants to DOUBLE PRECISION. REAL variables will be single precision (4 bytes in length).

-Mr8intrinsics

(Fortran only) The compiler treats the intrinsics CMPLX and REAL as DCMPLX and DBLE, respectively.

-Mnor8intrinsics

(Fortran only) The compiler does not promote the intrinsics CMPLX and REAL to DCMPLX and DBLE, respectively.

-Msafeptr[=option[,option,...]]

(C++ and C only) instructs the C++ or C compiler to override data dependencies between pointers of a given storage class. Possible values of option include:

all

assume all pointers and arrays are independent and safe for aggressive optimizations, and in particular that no pointers or arrays overlap or conflict with each other.

arg

instructs the compiler to treat arrays and pointers with the same copyin and copyout semantics as Fortran dummy arguments.

global

instructs the compiler that global or external pointers and arrays do not overlap or conflict with each other and are independent.

local/auto

instructs the compiler that local pointers and arrays do not overlap or conflict with each other and are independent.

static

instructs the compiler that static pointers and arrays do not overlap or conflict with each other and are independent.

-M[no]target_temps

instructs the compiler to enable [disable] using temporaries when passing an array for a callee assumed-shape variable with the target attribute.

-Munroll[=option [,option...]]

invokes the loop unroller to execute multiple instances of the loop during each iteration. This also sets the optimization level to 2 if the level is set to less than 2, or if no -⁠O or -⁠g options are supplied. The option is one of the following:

c:m

instructs the compiler to completely unroll loops with a constant loop count less than or equal to m, a supplied constant. If this value is not supplied, the m count is set to 1.

m:<n>

instructs the compiler to unroll multi-block loops n times. This option is useful for loops that have conditional statements. If n is not supplied, then the default value is 1. The default setting is not to enable -⁠Munroll=m.

n:<n>

instructs the compiler to unroll single-block loops n times, a loop that is not completely unrolled, or has a non-constant loop count. If n is not supplied, the unroller computes the number of times a candidate loop is unrolled.

-Mnounroll

instructs the compiler not to unroll loops.

-M[no]vect[=option [,option,...]]

enable [disable] the code vectorizer, where option is one of the following:

[no]altcode

Enable [disable] generation of alternate code (altcode) for vectorized loops when appropriate. For each vectorized loop the compiler decides whether to generate altcode and what type or types to generate, which may be any or all of: altcode without iteration peeling, altcode with non-temporal stores and other data cache optimizations, and altcode based on array alignments calculated dynamically at runtime. The compiler also determines suitable loop count and array alignment conditionals for executing the altcode. This option is enabled by default.

[no]assoc

Enable [disable] certain associativity conversions that can change the results of a computation due to roundoff error. A typical optimization is to change an arithmetic operation to an arithmetic operation that is mathematically correct, but can be computationally different, due to round-off error.

cachesize:n

Instructs the vectorizer, when performing cache tiling optimizations, to assume a cache size of n. The default is set per processor type, either using the -⁠tp switch or auto-detected from the host computer.

[no]fuse

Enable [disable] automatic loop fusion by the vectorizer.

[no]gather

Enable [disable] vectorization of loops containing indirect array references, such as this one:

sum = 0.d0
do k=d(j),d(j+1)-1
     sum = sum + a(k)*b(c(k))
enddo

The default is gather.

[no]idiom

Enable [disable] idiom recognition by the vectorizer.

levels:n

Maximum nest level of loops to optimize

nocond

Disable vectorization of loops with conditionals.

[no]partial

Enable [disable] partial loop vectorization through innermost loop distribution.

prefetch

Instructs the vectorizer to search for vectorizable loops and, wherever possible, make use of prefetch instructions.

[no]short

Enable [disable] short vector operations. -Mvect=short enables generation of packed SIMD instructions for short vector operations that arise from scalar code outside of loops or within the body of a loop iteration.

[no]simd[:{128|256|512}]

Enable [disable] vectorization using SIMD instructions and data, either 128 bits, 256 bits or 512 bits wide, on processors where there is a choice.

[no]simdresidual

Enable [disable] vectorization using SIMD instructions of the residual iterations of a vectorized loop.

[no]sizelimit:n

Instructs the vectorizer to generate vector code for all loops where possible regardless of the number of statements in the loop. This overrides a heuristic in the vectorizer that ordinarily prevents vectorization of loops with a number of statements that exceeds a certain threshold. The default is nosizelimit.

[no]uniform

Instructs the vectorizer to perform the same optimizations in the vectorized and residual loops.

Note: This option may affect the performance of the residual loop.

-Mnovintr

instructs the compiler not to perform idiom recognition or introduce calls to hand-optimized vector functions.

This section describes the -⁠M<nvflag> options that do not easily fit into one of the other categories of -⁠M<nvflag> options.

Default: Before looking at all the options, let’s look at the defaults. For arguments that you do not specify, the default miscellaneous options are as follows:

Related options: -⁠m, -⁠S, -⁠V, -⁠v

Usage: In the following example, the compiler includes Fortran source code with the assembly code.

 $ nvfortran -Manno -S myprog.f

In the following example, the assembler does not delete the assembly file myprog.s after the assembly pass.

 $ nvfortran -Mkeepasm myprog.f

In the following example, the compiler displays information about inlined functions with fewer than approximately 20 source lines in the source file myprog.f.

 $ nvfortran -Minfo=inline -Minline=20 myprog.f

In the following example, the compiler creates the listing file myprog.lst.

 $ nvfortran -Mlist myprog.f

In the following example, array bounds checking is enabled.

 $ nvfortran -Mbounds myprog.f

The following list provides the syntax for each miscellaneous -⁠M<nvflag> option. Each option has a description and, if appropriate, a list of any related options.

-Manno

annotate the generated assembly code with source code. Implies -⁠Mkeepasm.

-M[no]bounds

Enables [disables] array bounds checking.

• If an array is an assumed size array, the bounds checking only applies to the lower bound.
• If an array bounds violation occurs during execution, an error message describing the error is printed and the program terminates. The text of the error message includes the name of the array, the location where the error occurred (the source file and the line number in the source), and information about the out of bounds subscript (its value, its lower and upper bounds, and its dimension).

The following is a sample error message:

NVFTN-F-Subscript out of range for array a (a.f: 2)
subscript=3, lower bound=1, upper bound=2, dimension=2

-Mbyteswapio

swap byte-order from big-endian to little-endian or vice versa upon input/output of Fortran unformatted data files.

-Mchkptr

instructs the compiler to check for pointers that are dereferenced while initialized to NULL (Fortran only).

-Mchkstk

instructs the compiler to check the stack for available space in the prologue of a function and before the start of a parallel region. Prints a warning message and aborts the program gracefully if stack space is insufficient. This option is useful when many local and private variables are declared in an OpenMP program.

-Mcpp[=option [,option,...]]

run the cpp-like preprocessor without execution of any subsequent compilation steps. This option is useful for generating dependence information to be included in makefiles.

Note: Only one of the m, md, mm or mmd options can be present; if multiple of these options are listed, the last one listed is accepted and the others are ignored.

The option is one or more of the following:

m

print makefile dependencies to stdout.

md

print makefile dependencies to filename.d, where filename is the root name of the input file being processed, ignoring system include files.

mm

print makefile dependencies to stdout, ignoring system include files.

mmd

print makefile dependencies to filename.d, where filename is the root name of the input file being processed, ignoring system include files.

[no]comment

do [do not] retain comments in output.

[suffix:]<suff>

use <suff> as the suffix of the output file containing makefile dependencies.

-Mgccbug[s]

instructs the compiler to match the behavior of certain gcc bugs.

-Miface[=option]

adjusts the calling conventions for Fortran, where option is one of the following:

cref

uses CREF calling conventions, no trailing underscores.

mixed_str_len_arg

places the lengths of character arguments immediately after their corresponding argument. Has affect only with the CREF calling convention.

nomixed_str_len_arg

places the lengths of character arguments at the end of the argument list. Has affect only with the CREF calling convention.

-Minfo[=option [,option,...]]

instructs the compiler to produce information on standard error, where option is one of the following:

all

instructs the compiler to produce all available -⁠Minfo information. Implies a number of suboptions:

-Minfo=accel,inline,ipa,loop,lre,mp,opt,par,vect,stdpar 

accel

instructs the compiler to enable accelerator information.

ftn

instructs the compiler to enable Fortran-specific information.

inline

instructs the compiler to display information about extracted or inlined functions. This option is not useful without either the -⁠Mextract or -⁠Minline option.

intensity

instructs the compiler to provide informational messages about the intensity of the loop. Specify <n> to get messages on nested loops.

• For floating point loops, intensity is defined as the number of floating point operations divided by the number of floating point loads and stores.
• For integer loops, the loop intensity is defined as the total number of integer arithmetic operations, which may include updates of loop counts and addresses, divided by the total number of integer loads and stores.
• By default, the messages just apply to innermost loops.

loop

instructs the compiler to display information about loops, such as information on vectorization.

lre

instructs the compiler to enable LRE, loop-carried redundancy elimination, information.

mp

instructs the compiler to display information about parallelization.

opt

instructs the compiler to display information about optimization.

par

instructs the compiler to enable parallelizer information.

stdpar

instructs the compiler to emit information about parallelization of C⁠+⁠+ parallel algorithms and Fortran DO CONCURRENT loops.

time

instructs the compiler to display compilation statistics.

unroll

instructs the compiler to display information about loop unrolling.

vect

instructs the compiler to enable vectorizer information.

-Minform=level

instructs the compiler to display error messages at the specified and higher levels, where level is one of the following:

fatal

instructs the compiler to display fatal error messages.

[no]file

instructs the compiler to print or not print source file names as they are compiled. The default is to print the names: -⁠Minform=file.

inform

instructs the compiler to display all error messages (inform, warn, severe and fatal).

severe

instructs the compiler to display severe and fatal error messages.

warn

instructs the compiler to display warning, severe and fatal error messages.

-Minstrumentation=option

Specifies the level of instrumentation calls generated, implies -Mframe. option is one of the following:

level

specifies the level of instrumentation calls generated.

function (default)

generates instrumentation calls for entry and exit to functions. Just after function entry and just before function exit, the following profiling functions are called with the address of the current function and its call site. (x86-64 only).

void __cyg_profile_func_enter (void *this_fn, void *call_site);
void __cyg_profile_func_exit (void *this_fn, void *call_site);

In these calls, the first argument is the address of the start of the current function.

-Mkeepasm

instructs the compiler to keep the assembly file as compilation continues. Normally, the assembler deletes this file when it is finished. The assembly file has the same filename as the source file, but with a .s extension.

-Mlist

instructs the compiler to create a listing file. The listing file is filename.lst, where the name of the source file is filename.f.

-Mnames={lowercase|uppercase}

specifies the case for the names of Fortran externals.

• lowercase - Use lowercase for Fortran externals.
• uppercase - Use uppercase for Fortran externals.

-Mneginfo[=option[,option,...]]

instructs the compiler to produce information on standard error, where option is one of the following:

all

instructs the compiler to produce all available information on why various optimizations are not performed.

accel

instructs the compiler to enable accelerator information.

concur

instructs the compiler to produce all available information on why loops are not automatically parallelized. In particular, if a loop is not parallelized due to potential data dependence, the variable(s) that cause the potential dependence are listed in the messages that you see when using the option -⁠Mneginfo.

ftn

instructs the compiler to enable Fortran-specific information.

inline

instructs the compiler to display information about extracted or inlined functions. This option is not useful without either the -⁠Mextract or -⁠Minline option.

loop

instructs the compiler to display information about loops, such as information on vectorization.

lre

instructs the compiler to enable LRE, loop-carried redundancy elimination, information.

mp

instructs the compiler to display information about parallelization.

opt

instructs the compiler to display information about optimization.

par

instructs the compiler to enable parallelizer information.

vect

instructs the compiler to enable vectorizer information.

-Mnolist

the compiler does not create a listing file. This is the default.

-Mnorpath

Do not add -⁠rpath to the link line.

-Mpreprocess

instruct the compiler to perform cpp-like preprocessing on assembly and Fortran input source files.

-Mwritable_strings

stores string constants in the writable data segment.

Note: Options -⁠Xs and -⁠Xst include -⁠Mwritable_strings.

This section describes the standard function calling sequence, including the stack frame, register usage, and parameter passing.

typedef struct {
    int a, b;
    double d; 
    } 
    structparam; 
    structparam s;
    int e, f, g, h, i, j, k; 
    float flt;  
    double m, n; 
    extern void func(int e, int f, structparam s, int g, int h,  
    float flt, double m, double n, int i, int j, int k);
    void func2() 
    {  
    func(e, f, s, g, h, flt, m, n, i, j, k); 
    }

/* File: testmain.c */
#include <stdio.h>
int
main() {
 long l_para1 = 2;
 float f_para2 = 1.0;
 double d_para3 = 0.5;
 float f_return;
 extern float sum_3(long para1, float para2, double para3);
 f_return = sum_3(l_para1, f_para2, d_para3);
 printf("Parameter one, type long = %ld\n", l_para1);
 printf("Parameter two, type float = %f\n", f_para2);
 printf("Parameter three, type double = %f\n", d_para3);
 printf("The sum after conversion = %f\n", f_return);
 return 0;
}
# File: sum_3.s
# Computes ( para1 + para2 ) + para3
	.text
	.align	16
	.globl	sum_3
sum_3:
	pushq	%rbp
	movq	%rsp, %rbp
	cvtsi2ssq %rdi, %xmm2
	addss	%xmm0, %xmm2
	cvtss2sd %xmm2,%xmm2
	addsd %xmm1, %xmm2
	cvtsd2ss %xmm2, %xmm2
	movaps	%xmm2, %xmm0
	popq	%rbp
	ret
	.type	sum_3, @function
	.size	sum_3,.-sum_3

Sections A2.4.1 through A2.4.4 of the ABI for Linux defines the Fortran supplement. The register usage conventions set forth in that document remain the same for Fortran.

INTEGER I, J
COMPLEX C
DOUBLE COMPLEX CD
DOUBLE PRECISION D
COMMON /COM/ i, j, c, cd, d

extern struct {
    int i;
    int j;
    struct {float real, imag;} c;
    struct {double real, imag;} cd;
    double d;
} com_;

extern "C" struct {
    int i;
    int j;
    struct {float real, imag;} c;
    struct {double real, imag;} cd;
    double d;
} com_;

CHARACTER*(*) FUNCTION CHF(C1, I)
CHARACTER*(*) C1
INTEGER I
END

extern void chf_();
char tmp[10];
char c1[9];
int i;
chf_(tmp, 10, c1, &i, 9);

To call these intrinsic functions from a C/C++ source, you must include the corresponding header file – one of the following:

The following table describes the data types that are defined for intrinsics:

The MMX/SSE intrinsics include functions for initializing variables of the types defined in the preceding table. The following sample program, example.c, illustrates the use of the SSE intrinsics _mm_add_ps and _mm_set_ps.

#include<xmmintrin.h>
 int main(){
 __m128 A, B, result;
 A = _mm_set_ps(23.3, 43.7, 234.234, 98.746); /* initialize A */
 B = _mm_set_ps(15.4, 34.3, 4.1, 8.6); /* initialize B */
 result = _mm_add_ps(A, B);
 return 0;
 }

$ nvc example.c -o myprog

Each message is numbered. Each message also lists the line and column number where the error occurs. A dollar sign ($) in a message represents information that is specific to each occurrence of the message.

Error message severities:

I

informative

W

warning

S

severe error

F

fatal error

V

variable

V000 Internal compiler error. $ $

This message indicates an error in the compiler, rather than a user error – although it may be possible for a user error to cause an internal error. The severity may vary; if it is informative or warning, correct object code was probably generated, but it is not safe to rely on this.

F001 Source input file name not specified

On the command line, source file name should be specified either before all the switches, or after them.

F002 Unable to open source input file: $

Source file name is misspelled, file is not in current working directory, or file is read protected.

F003 Unable to open listing file

This message typically occurs when the user does not have write permission for the current working directory.

F004 $ $

Generic message for file errors.

F005 Unable to open temporary file

Compiler uses directory "/usr/tmp" or "/tmp" in which to create temporary files. If neither of these directories is available on the node on which the compiler is being used, this error will occur.

S006 Input file empty

Source input file does not contain any Fortran statements other than comments or compiler directives.

F007 Subprogram too large to compile at this optimization level $

Internal compiler data structure overflow, working storage exhausted, or some other non-recoverable problem related to the size of the subprogram. If this error occurs at opt level 2, reducing the opt level to 1 may work around the problem. Moving the subprogram being compiled to its own source file may eliminate the problem.

F008 Error limit exceeded

The compiler gives up because too many severe errors were issued; the error limit can be reset on the command line.

F009 Unable to open assembly file

This message typically occurs when the user does not have write permission for the current working directory.

F010 File write error occurred $

The file system may be full.

S011 Unrecognized command line switch: $

Refer to the HPC Compiler User Guide for a list of allowed compiler switches.

S012 Value required for command line switch: $

Certain switches require an immediately following value, such as "-opt 2".

S013 Unrecognized value specified for command line switch: $

S014 Ambiguous command line switch: $

Too short an abbreviation was used for one of the switches.

W015 Hexadecimal or octal constant truncated to fit data type

I016 Identifier, $, truncated to 63 chars

An identifier may be at most 63 characters in length; characters after the 63rd are ignored.

S017 Unable to open include file: $

File is missing, read protected, or maximum include depth (10) exceeded. Remember that the file name should be enclosed in quotes.

S018 Illegal label $ $

Used for label ‘field’ errors or illegal values. E.g., in fixed source form, the label field (first five characters) of the indicated line contains a non-numeric character.

S019 Illegally placed continuation line

A continuation line does not follow an initial line, or more than 99 continuation lines were specified.

S020 Unrecognized compiler directive

S021 Label field of continuation line is not blank

The first five characters of a continuation line must be blank.

S022 Unexpected end of file - missing END statement

The source file is missing and END statement, or the file is truncated.

S023 Syntax error - unbalanced $

Unbalanced parentheses or brackets.

W024 CHARACTER or Hollerith constant truncated to fit data type

A character or hollerith constant was converted to a data type that was not large enough to contain all of the characters in the constant. This type conversion occurs when the constant is used in an arithmetic expression or is assigned to a non-character variable. The character or hollerith constant is truncated on the right, that is, if 4 characters are needed then the first 4 are used and the remaining characters are discarded.

W025 Illegal character ($) - ignored

The current line contains a character, possibly non-printing, which is not a legal Fortran character (characters inside of character or Hollerith constants cannot cause this error). As a general rule, all non-printing characters are treated as white space characters (blanks and tabs); no error message is generated when this occurs. If for some reason, a non-printing character is not treated as a white space character, its hex representation is printed in the form dd where each d is a hex digit.

S026 Unmatched quote

A character constant is missing a closing quote or the source file is truncated.

S027 Illegal integer constant: $

Integer constant is too large for 32 bit word.

S028 Illegal real or double precision constant: $

S029 Illegal $ constant: $

Illegal hexadecimal, octal, or binary constant. A hexadecimal constant consists of digits 0..9 and letters A..F or a..f; any other character in a hexadecimal constant is illegal. An octal constant consists of digits 0..7; any other digit or character in an octal constant is illegal. A binary constant consists of digits 0 or 1; any other digit or character in a binary constant is illegal.

S030 Explicit shape must be specified for $

A shape for an array expression is effected in this context.

S031 Illegal data type length specifier for $

The data type length specifier (e.g. 4 in INTEGER*4) is not a constant expression that is a member of the set of allowed values for this particular data type.

W032 Data type length specifier not allowed for $

The data type length specifier (e.g. 4 in INTEGER*4) is not allowed in the given syntax (e.g. DIMENSION A(10)*4).

S033 Illegal use of constant $

A constant was used in an illegal context, such as on the left side of an assignment statement or as the target of a data initialization statement.

S034 Syntax error at or near $

Illegal command specified.

I035 Predefined intrinsic $ loses intrinsic property

An intrinsic name was used in a manner inconsistent with the language definition for that intrinsic. The compiler, based on the context, will treat the name as a variable or an external function.

S036 Illegal implicit character range

First character must alphabetically precede second.

S037 Contradictory data type specified for $

The indicated identifier appears in more than one type specification statement and different data types are specified for it.

S038 Symbol, $, has not been explicitly declared

The indicated identifier must be declared in a type statement; this is required when the IMPLICIT NONE statement occurs in the subprogram.

W039 Symbol, $, appears illegally in a SAVE statement $

An identifier appearing in a SAVE statement must be a local variable or array.

S040 Illegal common variable $

Indicated identifier is a dummy variable, is already in a common block, or has previously been defined to be something other than a variable or array.

W041 Illegal use of dummy argument $

This error can occur in several situations. It can occur if dummy arguments were specified on a PROGRAM statement. It can also occur if a dummy argument name occurs in a DATA, COMMON, SAVE, or EQUIVALENCE statement. A program statement must have an empty argument list.

S042 $ is a duplicate dummy argument

Each dummy argument must have a unique name.

S043 Illegal attempt to redefine $ $

An attempt was made to define a symbol in a manner inconsistent with an earlier definition of the same symbol. This can happen for a number of reasons. The message attempts to indicate the situation that occurred.

intrinsic – An attempt was made to redefine an intrinsic function. A symbol that represents an intrinsic function may be redefined if that symbol has not been previously verified to be an intrinsic function. For example, the intrinsic sin can be defined to be an integer array. If a symbol is verified to be an intrinsic function via the INTRINSIC statement or via an intrinsic function reference then it must be referred to as an intrinsic function for the remainder of the program unit.

symbol – An attempt was made to redefine a symbol that was previously defined. An example of this is to declare a symbol to be a PARAMETER which was previously declared to be a subprogram argument.

S044 Multiple declaration for symbol $

A redundant declaration of a symbol has occurred. For example, an attempt was made to declare a symbol as an ENTRY when that symbol was previously declared as an ENTRY.

S045 Data type of entry point $ disagrees with function $

The current function has entry points with data types inconsistent with the data type of the current function. For example, the function returns type character and an entry point returns type complex.

S046 Data type length specifier in wrong position

The CHARACTER data type specifier has a different position for the length specifier from the other data types. Suppose, we want to declare arrays ARRAYA and ARRAYB to have 8 elements each having an element length of 4 bytes. The difference is that ARRAYA is character and ARRAYB is integer. The declarations would be CHARACTER ARRAYA(8)*4 and INTEGER ARRAYB*4(8).

S047 More than seven dimensions specified for array

The compiler currently supports up to seven dimensions for arrays.

S048 Illegal use of '*' in declaration of array $

An asterisk may be used only as the upper bound of the last dimension.

S049 Illegal use of '*' in non-subroutine subprogram

The alternate return specifier ‘*’ is legal only in the subroutine statement. Programs, functions, and block data are not allowed to have alternate return specifiers.

S050 Assumed size array, $, is not a dummy argument

Arrays with ‘*’ in their dimension(s) may only be declared as dummy arguments.

S051 Unrecognized built-in % function

The allowable built-in functions are %VAL, %REF, %LOC, and %FILL. One was encountered that did not match one of these allowed forms.

S052 Illegal argument to %VAL or %LOC

S053 %REF or %VAL not legal in this context

The built-in functions %REF and %VAL can only be used as actual parameters in procedure calls.

W054 Implicit character $ used in a previous implicit statement

An implicit character has been given an implied data type more than once. The implied data type for the implicit character is changed anyway.

W055 Multiple implicit none statements

The IMPLICIT NONE statement can occur only once in a subprogram.

W056 Implicit type declaration