Chapter 42.

Xtensa Dependent Features

This chapter covers features of the gnu assembler that are specific to the Xtensa architecture. For

details about the Xtensa instruction set, please consult the [Xtensa Instruction Set Architecture (ISA)

Reference Manual].

42.1. Command Line Options

The Xtensa version of the gnu assembler supports these special options:

 density |  no density

Enable or disable use of the Xtensa code density option (16 bit instructions). Section 42.3.1

Using Density Instructions. If the processor is configured with the density option, this is enabled

by default; otherwise, it is always disabled.

 relax |  no relax

Enable or disable relaxation of instructions with immediate operands that are outside the le 

gal range for the instructions. Section 42.4 Xtensa Relaxation. The default is

 relax

and this

default should almost always be used. If relaxation is disabled with

 no relax

, instruction

operands that are out of range will cause errors. Note: In the current implementation, these op 

tions also control whether assembler optimizations are performed, making these options equiva 

lent to

 generics

and

 no generics

.

 generics |  no generics

Enable or disable all assembler transformations of Xtensa instructions, including both relax 

ation and optimization. The default is

 generics

;

 no generics

should only be used in the

rare cases when the instructions must be exactly as specified in the assembly source. As with

 no relax

, using

 no generics

causes out of range instruction operands to be errors.

 text section literals |  no text section literals

Control the treatment of literal pools. The default is

 no text section literals

, which

places literals in a separate section in the output file. This allows the literal pool to be placed

in a data RAM/ROM, and it also allows the linker to combine literal pools from separate object

files to remove redundant literals and improve code size. With

 text section literals

, the

literals are interspersed in the text section in order to keep them as close as possible to their

references. This may be necessary for large assembly files.

 target align |  no target align

Enable or disable automatic alignment to reduce branch penalties at some expense in code size.

Section 42.3.2 Automatic Instruction Alignment. This optimization is enabled by default. Note

that the assembler will always align instructions like

LOOP

that have fixed alignment require 

ments.

 longcalls |  no longcalls

Enable or disable transformation of call instructions to allow calls across a greater range of

addresses. Section 42.4.2 Function Call Relaxation. This option should be used when call targets

can potentially be out of range, but it degrades both code size and performance. The default is

 no longcalls

.