I've been looking into compiling smaller executables, and the
trick I learned from watching sessions from the last DConf is to
use the KEEP symbol in a linker script with something like
gc-sections. So at the compilation stage, symbols are put in
different sections, a linker script marks some symbols to be kept
if they are not referenced, and then unreferenced symbols are
removed, resulting in sometimes very small executables.
The problem is that if you don't KEEP some symbols for druntime,
or in your own program, you can run into errors because symbols
which weren't apparently referenced now get used and your program
breaks. I was just thinking, "There must be a GCC extension for
doing this without a linker script," I *think* there might be.
From what I just read, __attribute__((used)) in GCC should do the
job, and I think it should be usable from GDC with its attribute
pragmas. I believe there's also an attribute for putting symbols
in particular sections. I'm wondering, supposing I'm not
completely wrong and this actually works, would it behoove us to
add some version() blocks for GDC (Also LDC?) in druntime and
flag all of the symbols like this appropriately, so that creating
executables with gc-sections will Just Work in some cases without
a linker script?
What do people think? Am I on to something, or I am just making
fanciful ideas which won't work?
- __attribute__((used)) and druntime w0rp via Digitalmars-d
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