Syntax:
The /transform_loops (or /optimize:5) option activates a group of loop transformation optimizations that apply to array references within loops. These optimizations can improve the performance of the memory system and usually apply to multiple nested loops. The loops chosen for loop transformation optimizations are always counted loops (which include DO or IF loops), but not uncounted DO WHILE loops).
In the visual development environment, specify the Apply Loop Transformation Optimizations in the Optimizations Compiler Option Category.
Conditions that typically prevent the loop transformation optimizations from occurring include subprogram references that are not inlined (such as an external function call), complicated exit conditions, and uncounted loops.
The types of optimizations associated with /transform_loops include the following:
The loop transformation optimizations are a subset of optimizations activated by /optimize:5. On ia32 systems, instead of specifying /transform_loops, you can specify /optimize:5. On ia64 systems, instead of specifying both /pipeline and /transform_loops, you can specify /optimize:5.
On ia64 systems, to specify loop transformation optimizations without software pipelining, do one of the following:
To determine whether using /transform_loops benefits your particular program, you should time program execution for the same program (or subprogram) compiled with and without loop transformation optimizations (such as with /transform_loops and /notransform_loops).
For more information, see Loop Transformations.