On Saturday, 16 August 2014 at 07:36:07 UTC, Johannes Pfau wrote:
Iain recently pushed a commit to put zero initializers into
bss, so
that's intentional:
http://bugzilla.gdcproject.org/show_bug.cgi?id=139
But I understand your point that it should be in rodata
instead, you'll
have to discuss this with Iain.
It is true that bss does not take place in the executable. But in
small processors, even there is nowadays plenty of rom there is
not enough ram. It is also a question of safety: in the long run,
data area may be corrupted by buggy program or electrical distort
while rodata in rom cannot be changed.
At least in my setup, gold maps bss to executable anyway while ld
does not.
I noticed your comment in the bug report. I was just thinking the
same: one big block of zeros that is used by all.
Another that I was thinking is that memset might be used for
these types. Then there would be no block of zeros at all. But
that would require an extra flag in typeinfo to separate these
types from others...
Regarding __Class: Can you post a short example?
Some lines from mapfile. Seems to be one for every type in the
program:
.data 0x0000000020001074 0x720
minlibd/libdruntime/libdruntime.a(object_.o)
0x0000000020001074
_D9Exception7__ClassZ
0x00000000200010c0
_D8TypeInfo7__ClassZ
0x000000002000110c
_D17TypeInfo_Function7__ClassZ
0x0000000020001158
_D17TypeInfo_Delegate7__ClassZ
0x00000000200011a4
_D14TypeInfo_Class7__ClassZ
0x00000000200011f0
_D18TypeInfo_Interface7__ClassZ
0x000000002000123c
_D15TypeInfo_Struct7__ClassZ
0x0000000020001288
_D16TypeInfo_Typedef7__ClassZ
In my application there will be several large structs. I never
create anything of these types. Instead I use them to point to
hardware registers and maybe on top of existing byte arrays
like message buffers. There will still be initial values for
these structs wasting memory. Is there any way to omit them?
See
https://github.com/D-Programming-GDC/GDC/pull/82
@attribute("noinit")
Yes this will solve the problem.
