Vax C90-EL SERIES Service Manual download pdf (Page 117)

#pragma Directives [3]

from memory at the first reference following the directive. The local suppress

directive has the following format:

#pragma _CRI suppress [var...]

The net effect of the local suppress directive is similar to declaring the affected

variables to be volatile except that the volatile qualifier affects the entire

program whereas the local suppress directive affects only the block of code

in which it resides.

On UNICOS/mk systems, suppress, with no arguments specified, invalidates

the entire cache or forces all entities in the cache to be read from memory. This

gives suppress a higher performance cost than it has on other architectures, so

specifying particular variables can be more efficient.

3.10.9 symmetric Directive (UNICOS/mk Systems)

Scope: Local

The symmetric directive declares that an auto or register variable has the

same local address on all processing elements (PEs). This is useful for global

addressing using the shmem library functions. For information on the shmem

library functions, see the intro_shmem(3) man page. The format for this

compiler directive is as follows:

#pragma _CRI symmetric var...

The symmetric directive must appear in local scope. Each variable listed on

the directive must:

• Be declared in the same scope as the directive.

• Have auto or register storage class.

• Not be a function parameter.

Because all PEs must participate in the allocation of symmetric stack variables,

there is an implicit barrier before the first executable statement in a block

containing symmetric variables.

If a goto statement jumps into a block where a symmetric variable has been

declared, the behavior is undefined. If a block is exited by means of a goto,

longjmp, and so on, the memory associated with any symmetric variables

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Vax C90-EL SERIES Service Manual Page 117