<chandrakumar@xxxxxxxxxxxxxxx> writes: > I am working with gcc-2.95.3 ported to a RISC architecture. gcc 2.95.3 is really old. > I did a modification in the port to insert 'nop' instruction. This is done > to fix a defect. When I built the compiler (with this fix) and used it to > build the glibc I got the assembler error "Relocation overflow". > > On analysis it is found that the RISC architecture has conditional > branches that can address destinations with a depth of 4000 bytes. This > limitation is not considered while doing the port. > > After the fix I did, some conditional branches addressed destination that > were beyond the 4000 bytes breaking the limitation. > > Now I want to fix this case as follows: > 1. Conditionally branch to the maximum depth it (a conditional branch) can > address (i.e. branch to a temporary place within the allowed range) > 2. Then jump from there to the actual destination. Most gcc ports address this by counting instruction sizes and choosing either a long or a short branch depending on how far the branch has to go. E.g., the MIPS port does this. For MIPS the long branch is a short conditional branch around a long unconditional branch. In mips.md see mips_output_conditional_branch and the value of the "length" attribute for an instruction with type "branch". If you are inserting nops in the compiler, then you should be able to calculate lenghts correctly. However, I have no idea if the framework for this was present in gcc 2.95.3. Ian
