On Tue, Feb 12, 2019 at 12:41:47PM +0100, Eric Botcazou wrote:
> > Ok, stand corrected on that, 128-bit indeed, but even that is nothing not
> > really used.
>
> The irony is that I'm doing this for 32-bit SPARC (we cannot get ASAN to work
> in 64-bit mode for the time being) and the maximum alignment on 32-bit SPARC
> is 64-bit (even long doubles) so this will be totally unused. ;-)
>
> > For STRICT_ALIGNMENT targets store merging pass obviously can't do anything
> > with those, because unlike asan.c it can't figure out the alignment.
>
> OK, revised patch attached. I have manually verified that it yields the
> expected result for an array of long doubles on 64-bit SPARC.
>
>
> 2019-02-12 Eric Botcazou <ebotca...@adacore.com>
>
> * asan.c (asan_expand_mark_ifn): Take into account the alignment of
> the object to pick the size of stores on strict-alignment platforms.
Ok, thanks.
> Index: asan.c
> ===================================================================
> --- asan.c (revision 268508)
> +++ asan.c (working copy)
> @@ -3218,7 +3218,10 @@ asan_expand_mark_ifn (gimple_stmt_iterat
> /* Generate direct emission if size_in_bytes is small. */
> if (size_in_bytes <= ASAN_PARAM_USE_AFTER_SCOPE_DIRECT_EMISSION_THRESHOLD)
> {
> - unsigned HOST_WIDE_INT shadow_size = shadow_mem_size (size_in_bytes);
> + const unsigned HOST_WIDE_INT shadow_size
> + = shadow_mem_size (size_in_bytes);
> + const unsigned int shadow_align
> + = (get_pointer_alignment (base) / BITS_PER_UNIT) >> ASAN_SHADOW_SHIFT;
>
> tree shadow = build_shadow_mem_access (iter, loc, base_addr,
> shadow_ptr_types[0], true);
> @@ -3226,9 +3229,11 @@ asan_expand_mark_ifn (gimple_stmt_iterat
> for (unsigned HOST_WIDE_INT offset = 0; offset < shadow_size;)
> {
> unsigned size = 1;
> - if (shadow_size - offset >= 4)
> + if (shadow_size - offset >= 4
> + && (!STRICT_ALIGNMENT || shadow_align >= 4))
> size = 4;
> - else if (shadow_size - offset >= 2)
> + else if (shadow_size - offset >= 2
> + && (!STRICT_ALIGNMENT || shadow_align >= 2))
> size = 2;
>
> unsigned HOST_WIDE_INT last_chunk_size = 0;
Jakub
