as: Literal Directive
9.54.5.4 literal
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The '.literal' directive is used to define literal pool data, i.e.,
read-only 32-bit data accessed via 'L32R' instructions.
.literal LABEL, VALUE[, VALUE...]
This directive is similar to the standard '.word' directive, except
that the actual location of the literal data is determined by the
assembler and linker, not by the position of the '.literal' directive.
Using this directive gives the assembler freedom to locate the literal
data in the most appropriate place and possibly to combine identical
literals. For example, the code:
entry sp, 40
.literal .L1, sym
l32r a4, .L1
can be used to load a pointer to the symbol 'sym' into register 'a4'.
The value of 'sym' will not be placed between the 'ENTRY' and 'L32R'
instructions; instead, the assembler puts the data in a literal pool.
Literal pools are placed by default in separate literal sections;
however, when using the '--text-section-literals' option (
Command-line Options Xtensa Options.), the literal pools for
PC-relative mode 'L32R' instructions are placed in the current
section.(1) These text section literal pools are created automatically
before 'ENTRY' instructions and manually after '.literal_position'
directives (literal_position Literal Position Directive.). If
there are no preceding 'ENTRY' instructions, explicit
'.literal_position' directives must be used to place the text section
literal pools; otherwise, 'as' will report an error.
When literals are placed in separate sections, the literal section
names are derived from the names of the sections where the literals are
defined. The base literal section names are '.literal' for PC-relative
mode 'L32R' instructions and '.lit4' for absolute mode 'L32R'
instructions (absolute-literals Absolute Literals Directive.).
These base names are used for literals defined in the default '.text'
section. For literals defined in other sections or within the scope of
a 'literal_prefix' directive (literal_prefix Literal Prefix
Directive.), the following rules determine the literal section name:
1. If the current section is a member of a section group, the literal
section name includes the group name as a suffix to the base
'.literal' or '.lit4' name, with a period to separate the base name
and group name. The literal section is also made a member of the
group.
2. If the current section name (or 'literal_prefix' value) begins with
"'.gnu.linkonce.KIND.'", the literal section name is formed by
replacing "'.KIND'" with the base '.literal' or '.lit4' name. For
example, for literals defined in a section named
'.gnu.linkonce.t.func', the literal section will be
'.gnu.linkonce.literal.func' or '.gnu.linkonce.lit4.func'.
3. If the current section name (or 'literal_prefix' value) ends with
'.text', the literal section name is formed by replacing that
suffix with the base '.literal' or '.lit4' name. For example, for
literals defined in a section named '.iram0.text', the literal
section will be '.iram0.literal' or '.iram0.lit4'.
4. If none of the preceding conditions apply, the literal section name
is formed by adding the base '.literal' or '.lit4' name as a suffix
to the current section name (or 'literal_prefix' value).
---------- Footnotes ----------
(1) Literals for the '.init' and '.fini' sections are always placed
in separate sections, even when '--text-section-literals' is enabled.
Info Catalog
as: Transform Directive
as: Xtensa Directives
as: Literal Position Directive