Hi folks,
I am having a little bit of trouble with ar and objcopy.
Unsure if I am doing something that I should not expect the tools to do,
or encountering a bug.
I am trying to localize some symbols in objects inside an archive.
Ultimately, it seems like the tools are failing because the .a appears
to contain an object with the name "bin/thumbv7em-none-eabihf.o".
This all started from trying:
arm-none-eabi-objcopy --localize-hidden librustlib.a
So operations like:
arm-none-eabi-objcopy -L __aeabi_dcmpgt librustlib.a
result in the error:
arm-none-eabi-objcopy: stsJ3ObR/bin/thumbv7em-none-eabihf.o: No such file or
directory
with apparently no change to the archive file.
The symbol is definitely in there:
arm-none-eabi-objdump -x librustlib.a
gives
compiler_builtins-2ff80b98fa64b741.compiler_builtins.6207f1bb-cgu.122.rcgu.o:
file format elf32-littlearm
rw-r--r-- 0/0 10176 Dec 31 16:00 1969
compiler_builtins-2ff80b98fa64b741.compiler_builtins.6207f1bb-cgu.122.rcgu.o
architecture: armv7e-m, flags 0x00000011:
...
SYMBOL TABLE:
00000000 l df *ABS* 00000000 compiler_builtins.6207f1bb-cgu.122
00000000 l d .text.__aeabi_dcmpgt 00000000 .text.__aeabi_dcmpgt
...
00000000 g F .text.__aeabi_dcmpgt 00000078 .hidden __aeabi_dcmpgt
So the symbol is there, flagged as a Function, .hidden, but still global.
Checking the contents of the archive:
arm-none-eabi-ar tv librustlib.a | grep thumb
it does appear that something is there:
rw-r--r-- 0/0 22732 Dec 31 16:00 1969 bin/thumbv7em-none-eabihf.o
When I try to extract everything in the archive:
arm-none-eabi-ar x librustlib.a
it extracts all objects up to that problem object with the '/' in the
name, but none after it.
Is this a bug?
This is actually part of a bigger effort on another issue of symbol
collision at link time:
https://github.com/rust-lang/compiler-builtins/issues/345
In short, both Rust and C export "builtins" for basic operations, e.g.
IEEE 754 float operations here, which collide when trying to statically
link the outputs together for an embedded target.
So I am trying to localize all the symbols in the .a before linking,
such that each of Rust and C will use their own impls of the builtins,
to avoid collision.
(I assume there is probably some more-correct way of resolving this
collision, so any input here would also be great!)
Thanks,
Andrew
