9.54.5 Directives

The Xtensa assembler supports a region-based directive syntax:

         .begin directive [options]
         ...
         .end directive

All the Xtensa-specific directives that apply to a region of code use this syntax.

The directive applies to code between the .begin and the .end. The state of the option after the .end reverts to what it was before the .begin. A nested .begin/.end region can further change the state of the directive without having to be aware of its outer state. For example, consider:

         .begin no-transform
     L:  add a0, a1, a2
         .begin transform
     M:  add a0, a1, a2
         .end transform
     N:  add a0, a1, a2
         .end no-transform

The ADD opcodes at L and N in the outer no-transform region both result in ADD machine instructions, but the assembler selects an ADD.N instruction for the ADD at M in the inner transform region.

The advantage of this style is that it works well inside macros which can preserve the context of their callers.

The following directives are available:

• Schedule Directive: Enable instruction scheduling.
• Longcalls Directive: Use Indirect Calls for Greater Range.
• Transform Directive: Disable All Assembler Transformations.
• Literal Directive: Intermix Literals with Instructions.
• Literal Position Directive: Specify Inline Literal Pool Locations.
• Literal Prefix Directive: Specify Literal Section Name Prefix.
• Absolute Literals Directive: Control PC-Relative vs. Absolute Literals.