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Re: RISC-V problem with weak function references and -mcmodel=medany
On 05/29/2018 04:19 AM, Sebastian Huber wrote:
Changing the code to something like this
void f(void) __attribute__((__weak__));
void _start(void)
{
void (*g)(void) = f;
if (g != 0) {
(*g)();
}
}
This testcase works for me also, using -mcmodel=medany -O tmp.c
-Ttext=0x80000000 -nostdlib -nostartfiles.
I need enough info to reproduce your problem in order to look at it.
One thing you can try is adding -Wl,--noinhibit-exec, which will produce
an executable even though there was a linker error, and then you can
disassemble the binary to see what you have for the weak call. That
might give a clue as to what is wrong.
Why doesn't the RISC-V generate a trampoline code to call far functions?
RISC-V is a new target. The answer to questions like this is that we
haven't needed it yet, and hence haven't implemented it yet. But I
don't see any need for trampolines to support a call to 0. We can reach
anywhere in the low 32-bit address space with auipc/jalr. We can also
use zero-relative addressing via the x0 register if necessary. We
already have some linker relaxation support for that, but it doesn't
seem to be triggering for this testcase.
Jim