As illustrated in the example below, when initializing a global
variable using a symbol reference, GCC generates .quad assembly
statement; and when initializing a local variable using a symbol
reference, GCC generates instructions.
Is there a way to make GCC generate instructions within the crti.S
_init function to initialize a global variable, instead of generating
.long or .quad assembly statement ?
The idea being to make GCC generate instructions to initialize a
global variable, just like it generates instructions to initialize a
local variable.
Example for illustrating GCC default initialization behavior when
initializing global variable myglobal and local variable mylocal:
void myfunc (void) {}
void *myglobal = myfunc;
void main (void) {
void *mylocal = myfunc;
}
GCC generates the following assembly:
.text
.globl myfunc
.type myfunc, @function
myfunc:
pushq %rbp #
movq %rsp, %rbp #,
# test.c:1: void myfunc (void) {}
nop
popq %rbp #
ret
.size myfunc, .-myfunc
.globl myglobal
.section .data.rel.local,"aw",@progbits
.align 8
.type myglobal, @object
.size myglobal, 8
myglobal:
.quad myfunc
.text
.globl main
.type main, @function
main:
pushq %rbp #
movq %rsp, %rbp #,
# test.c:4: void *mylocal = myfunc;
leaq myfunc(%rip), %rax #, tmp87
movq %rax, -8(%rbp) # tmp87, mylocal
# test.c:5: }
nop
popq %rbp #
ret
.size main, .-main
