MIPS JAL/JALR to BAL transformation for Linux (o32 ABI)

[Richard Sandiford]

Adam Nemet <anemet@caviumnetworks.com> writes:
> Adam Nemet <anemet@caviumnetworks.com> writes:
>> "Fu, Chao-Ying" <fu@mips.com> writes:
>>> In order to utilize this optimization, we need to
>>> use -mno-explicit-relocs for GCC to let the assembler emit
>>> BFD_RELOC_MIPS_JALR for shared libraries (-mshared).
>>
>> I agree that we should try to use BAL in shared libraries.  However it
>> seems to me that requiring -mno-explicit-relocs is a high price to pay.
>> Can't we instead change the calls in shared libraries to also use the
>> PLT (or the locally binding function directly if possible)?
>
> If we can't do this there is also the other idea which we used to do to
> avoid -mno-explicit-relocs in our toolchain.  Emit jalr and jr with an
> extra optional operand that is the symbol name of the function for PIC
> calls and use that to create the JALR relocation.

Yeah.  These days we could also use (thanks Alan!):

	.reloc	1f, R_MIPS_JALR, foo
1:	jalr	$25

Does that mean you already have a GCC patch to do this kind of thing?

Richard