Vax C90-EL SERIES Service Manual download pdf (Page 35)

Compiler Commands [2]

(=f), or each this pointer (=t) points to a unique object. This assumption

eliminates those pointers as sources of potential aliasing, and may allow

additional vectorization or other optimizations. These options cause only

data dependencies from pointer aliasing to be ignored, rather than all data

dependencies, so they can be used safely for more programs than the -h ivdep

option.

Caution: Like -h ivdep, the arguments make assertions about your program

that, if incorrect, can introduce undefined behavior. You should not use

-h restrict=a if, during the execution of any function, an object is modified

and that object is referenced through either of the following:

• Two different pointers

• The declared name of the object and a pointer

The -h restrict=f and -h restrict=t options are subject to the

analogous restriction, with "function parameter pointer" replacing "pointer."

2.7.3 -h [no]calchars (CC, cc)

Default option: -h nocalchars

The -h calchars option allows the use of the @ and $ characters in identifier

names. This option is useful for porting codes in which identifiers include these

characters. With -h nocalchars, these characters are not allowed in identifier

names.

Caution: Use this option with extreme care, because identifiers with these

characters are within UNICOS and UNICOS/mk name space and are included

in many library identifiers, internal compiler labels, objects, and functions.

You must prevent conflicts between any of these uses, current or future, and

identifier declarations or references in your code; any such conflict is an error.

2.7.4 -h [no]signedshifts (CC, cc)

Default option: -h signedshifts

(UNICOS/mk systems) The -h [no]signedshifts option affects the result

of the right shift operator. For the expression e1 e2 where e1 has a signed

type, when -h signedshifts is in effect, the vacated bits are filled with the

sign bit of e1. When -h nosignedshifts is in effect, the vacated bits are

filled with zeros, identical to the behavior when e1 has an unsigned type. The

-h nosignedshifts option forces the operator to have the same behavior on

UNICOS/mk operating systems as on UNICOS operating systems.

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Vax C90-EL SERIES Service Manual Page 35