REG_CX
ctx->uc_mcontext.gregs[REG_CX] = 0;
requested_regs[REG_CX] = *ssptr(ctx); /* The asm code does this. */
greg_t asm_ss = ctx->uc_mcontext.gregs[REG_CX];
if (i == REG_CX && req != res) {