Re: [Valgrind-developers] Dealing with 32-byte loads/stores in Cachegrind/Callgrind

[Nicholas N. <n.n...@gm...>]

On Mon, May 21, 2012 at 7:22 AM, Julian Seward <js...@ac...> wrote:
>
> I recently added some AVX support to V, and as a result added a new type
> of 32-byte values (Ity_V256) to IR.  Loads and stores of such values
> cause Cachegrind and Callgrind to assert, because the size (32 bytes)
> is larger than MIN_LINE_SIZE, which is 16.
>
> As they currently are, both tools refuse to process memory accesses
> bigger than 16, on the basis that the minimum possible line size is 16,
> and so a 16 byte access could access 2 adjacent lines, which is a
> situation they are prepared to handle.  But not 3 lines, which is a
> possible case for a 32 byte access w/ 16 byte lines (something for
> which I'm sure no hardware actually exists).

Can we model the 32-byte accesses correctly and just assert if the 3
line case occurs?  (I wrote that simulation code so long ago that I
don't have any additional insight compared to someone looking at it
afresh...)

Nick