Re: [PATCH] linux-user: limit check to HOST_LONG_BITS == 32

[Peter Maydell]

On Thu, 21 May 2020 at 11:22, Alex Bennée <address@hidden> wrote:
>
> Newer clangs rightly spot that you can never exceed the full address
> space of 64 bit hosts with:
>
>   linux-user/elfload.c:2076:41: error: result of comparison 'unsigned
>   long' > 18446744073709551615 is always false
>   [-Werror,-Wtautological-type-limit-compare]
>   4685         if ((guest_hiaddr - guest_base) > ~(uintptr_t)0) {
>   4686             ~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~
>   4687 1 error generated.
>
> So lets limit the check to 32 bit hosts only.
>
> Fixes: ee94743034bf
> Reported-by: Thomas Huth <address@hidden>
> Signed-off-by: Alex Bennée <address@hidden>
> ---
>  linux-user/elfload.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index 01a9323a637..797fbf2337a 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -2072,6 +2072,7 @@ static void pgb_have_guest_base(const char *image_name, 
> abi_ulong guest_loaddr,
>                           image_name, (uint64_t)guest_hiaddr, reserved_va);
>              exit(EXIT_FAILURE);
>          }
> +#if HOST_LONG_BITS == 32
>      } else {
>          if ((guest_hiaddr - guest_base) > ~(uintptr_t)0) {
>              error_report("%s: requires more virtual address space "
> @@ -2079,6 +2080,7 @@ static void pgb_have_guest_base(const char *image_name, 
> abi_ulong guest_loaddr,
>                           image_name, (uint64_t)guest_hiaddr - guest_base);
>              exit(EXIT_FAILURE);
>          }
> +#endif

Could we write this so that we have the #if...#endif
conditional nested inside the if { ... } else { ... },
rather than having the two conditional constructs
oddly intermeshed?

thanks
-- PMM