https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106270
--- Comment #1 from qinzhao at gcc dot gnu.org ---
from Jose Marchesi:
====
We looked at this issue and these are our findings.
- When this problem happens:
When the linker (ld) fails to insert a veneer (that transforms the
immediate bl jumps generated by GCC into an indirect call) in range
with the original bl instruction.
This issue happens because it contains .text sections bigger than
~128MiB or when the range between a bl instruction and the
beginning/or/end of the containing section exceeds ~128MiB.
Note that this also happens with linker-generated PLT sections when
linking shared objects, much like the veneers.
- Proposed solutions:
We can think on two complementary solutions:
a) At the moment the aarch64 linker seems to only know how to insert a
veneer _after_ the section that contains the branch/call
instruction. We could make the linker smarter so it knows how to
insert the veneer _before_ the sect on containing the branch/call
instruction.
This would make things better, but obviously would not work in all
cases.
b) So, in any case, we propose to add a new option to GCC (aarch64
specific) that will make GCC to generate indirect branch
instructions (blr) for non-PLT calls to symbols not having local
binding/scope:
-mlong-calls -> Make aarch64_is_long_call_p return true
-> This makes GCC to generate blr instead of bl
when compiling non-PIC and calls to symbol
references with non-local binding.
-> This will have an impact in performance, but
this will _not_ impact inter-section calls nor
to calls to local objects.
