Re: [Xen-devel] [PATCH] libxc/arm: initialise p2m_size to make gcc happy

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 14/03/18 12:32, Wei Liu wrote:
> Gcc with -O3 failed to spot the loop to initialise p2m_size runs at
> least once.

It is -Og in this case, rather than -O3.  My -O3 comment on the thread
was for the more generic cases.

~Andrew

>
> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> ---
>  tools/libxc/xc_dom_arm.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/tools/libxc/xc_dom_arm.c b/tools/libxc/xc_dom_arm.c
> index 5b9eca6087..97d08f055a 100644
> --- a/tools/libxc/xc_dom_arm.c
> +++ b/tools/libxc/xc_dom_arm.c
> @@ -395,7 +395,7 @@ static int meminit(struct xc_dom_image *dom)
>      const uint64_t modsize = dtb_size + ramdisk_size;
>      const uint64_t ram128mb = bankbase[0] + (128<<20);
>  
> -    xen_pfn_t p2m_size;
> +    xen_pfn_t p2m_size = 0; /* make gcc -O3 happy */
>      uint64_t bank0end;
>  
>      assert(dom->rambase_pfn << XC_PAGE_SHIFT == bankbase[0]);
> @@ -438,6 +438,7 @@ static int meminit(struct xc_dom_image *dom)
>  
>      assert(dom->rambank_size[0] != 0);
>      assert(ramsize == 0); /* Too much RAM is rejected above */
> +    assert(p2m_size != 0);
>  
>      dom->p2m_size = p2m_size;
>      dom->p2m_host = xc_dom_malloc(dom, sizeof(xen_pfn_t) * p2m_size);


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