Function clear_overwritten_gprs

objdiff-core/src/arch/ppc/mod.rs:809–826

Remove the relocation we're keeping track of in a particular register when an instruction reuses that register to hold some other value, unrelated to pool relocation addresses.

(ins: powerpc::Ins, gpr_pool_relocs: &mut BTreeMap<u8, Relocation>)

// Remove the relocation we're keeping track of in a particular register when an instruction reuses
// that register to hold some other value, unrelated to pool relocation addresses.
fn clear_overwritten_gprs(ins: powerpc::Ins, gpr_pool_relocs: &mut BTreeMap<u8, Relocation>) {
    use powerpc::{Argument, Arguments, Opcode};
    let mut def_args = Arguments::default();
    ins.parse_defs(&mut def_args);
    for arg in def_args {
        if let Argument::GPR(gpr) = arg {
            if ins.op == Opcode::Lmw {
                // `lmw` overwrites all registers from rd to r31.
                // powerpc only returns rd itself, so we manually clear the rest of them.
                for reg in gpr.0..31 {
                    gpr_pool_relocs.remove(&reg);
                }
                break;
            }
            gpr_pool_relocs.remove(&gpr.0);
        }
    }
}

// We create a fake relocation for an instruction, vaguely simulating what the actual relocation
// might have looked like if it wasn't pooled. This is so minimal changes are needed to display