AN3350 datasheet(172/185 Pages) STMICROELECTRONICS

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Pragmas for optimization

AN3350

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Doc ID 018512 Rev 2

22.7

opt_propagation

Controls the use of copy and constant propagation optimization.

Syntax

#pragma opt_propagation on | off | reset

Remarks

If you enable this pragma, the compiler replaces multiple occurrences of one variable with a

single occurrence.

This pragma does not correspond to any panel setting. By default, this settings is related to

the global_optimizer level.

22.8

opt_strength_reduction

Controls the use of strength reduction optimization.

Syntax

#pragma opt_strength_reduction on | off | reset

Remarks

If you enable this pragma, the compiler replaces array element arithmetic instructions with

pointer arithmetic instructions to make loops faster.

This pragma does not correspond to any panel setting. By default, this settings is related to

the global_optimizer level.

22.9

opt_strength_reduction_strict

Uses a safer variation of strength reduction optimization.

Syntax

#pragma opt_strength_reduction_strict on | off | reset

Remarks

Like the opt_strength_reduction pragma, this setting replaces multiplication instructions that

are inside loops with addition instructions to speed up the loops. However, unlike the regular

strength reduction optimization, this variation ensures that the optimization is only applied

when the array element arithmetic is not of an unsigned type that is smaller than a pointer

type.

This pragma does not correspond to any panel setting. The default varies according to the

compiler.

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