-qdirectstorage

Description

Informs the compiler that write-through enabled or cache-inhibited storage may be referenced.

Syntax

Read syntax diagramSkip visual syntax diagram        .-nodirectstorage-.
>>- -q--+-directstorage---+------------------------------------><

Notes

The -qdirectstorage compiler option informs the compiler that write-through enabled or cache-inhibited storage may be referenced, and that appropriate compiler output should be generated.

The PowerPC architecture allows many different implementations of cache organization. To ensure that your application will execute correctly on all implementations, you should assume that separate instruction and data caches exist and program your application accordingly.

Depending on the storage control attributes specified by the program and the function being performed, your program may use cache instructions to guarantee that the function is performed correctly.

For example, the dcbz instruction allocates a block of data in the cache and then initializes it to a series of zeroes. Though it can be used to boost performance when zeroing a large block of data, the dcbz instruction should be used with caution because it will cause an alignment error to occur under any of the following conditions:

Specifying -qdirectstorage will suppress generation of the dcbz instruction, and avoid the alignment errors mentioned above.

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