https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111134
Bug ID: 111134
Summary: Sections for static data declared in functions with
section attribute
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: manuelhohmann at online dot de
Target Milestone: ---
Using the section attribute, functions can be placed in specific sections.
However, this only places the code in the named section. However, static
variables, static constants and string literals are not affected by this.
Example:
void __attribute__ ((section ".my.text")) testfunc(void)
{
static char data[] = {0, 1, 2, 3};
static const char rodata[] = {4, 5, 6, 7};
puts("test");
}
This will place data in .data, rodata in .rodata and "test" in .rodata.strM.N
(where M and N is related to alignment). The function code itself is in
.my.text.
For the two arrays, one can change the section:
void __attribute__ ((section ".my.text")) testfunc(void)
{
static char __attribute__ ((section ".my.data")) data[] = {0, 1, 2, 3};
static const char __attribute__ ((section ".my.rodata")) rodata[] = {4, 5,
6, 7};
puts("test");
}
This will place them in .my.data and .my.rodata, respectively. However, there
does not seem to be a possibility to do this with string literals. One could
define them as constant char arrays as a workaround. Also there does not seem
to be a possibility to change the section of all static data items in a
function at once.
Would it be possible to allow such functionality e.g. by introducing function
attributes such as
data_section
rodata_section
string_section
which change the names of the sections, but otherwise retain their attributes
(such as mergeable, string for the string literals)? Or / and e.g. a function
attribute along the lines of
__attribute__ ((section_prefix ".my"))
that will prefix all section names (.text, .data, .rodata, .rodata.strM.N) with
the given string for the function and its associated data?
---
Rationale / example use: For certain environments, such as embedded code or
operating system kernels, a boot loader will load a single executable into
memory, containing both initialization and permanent code. Placing
initialization code into a separate section allows to free the occupied memory
once initialization is completed and the code is no longer used. It would be
helpful if along with a function's code also all of its associated data could
be assigned a custom section.
