Re: [Qemu-devel] [PATCH 2/5] Add a PowerPC branch detector

[Thiemo Seufer <ths@networkno.de>]

Alexander Graf wrote:
> PowerPCs have static instruction lengths, so writing an "in-between" brl
> detection is quite simple on this architecture. You are welcome to write
> something like this for any other platform, but if a compile doesn't
> trigger build errors on PowerPC, it shouldn't on other platforms either,
> as PowerPC has quite advanced branch instructions.
> 
> This patch is not mandatory, makes debugging a lot easier though.

> Index: qemu-snapshot-2008-01-15_05/dyngen.c
> ===================================================================
> --- qemu-snapshot-2008-01-15_05.orig/dyngen.c
> +++ qemu-snapshot-2008-01-15_05/dyngen.c
> @@ -1488,6 +1488,16 @@ void gen_code(const char *name, host_ulo
>          if (get32((uint32_t *)p) != 0x4e800020)
>              error("blr expected at the end of %s", name);
>          copy_size = p - p_start;
> +
> +/* blr check for inline returns */
> +
> +        if(strstart(name, "op_", NULL) && !strstart(name, "op_exit", NULL)) {
> +            for(p=p_start; p < p_end - 4; p+=4) {
> +                if ((get32((uint32_t *)p) & 0xfc00fff0) == 0x4c000020) {
> +                    error("Inline blr detected in %s. Please append FORCE_RET to the function.", name);
> +                }
> +            }
> +        }

Is check_ops.sh not enough for debugging micro-ops?


Thiemo