On Thu, 18 Jan 2024, Jakub Jelinek wrote:
> Hi!
>
> On aarch64 the backend decides to use non-BLKmode for some arrays
> like unsigned long[4] - OImode in that case, but the corresponding
> BITINT_TYPEs have BLKmode (like structures containing that many limb
> elements). This both isn't a good idea (we really want such underlying vars
> to live in memory and access them there, rather than live in registers and
> access their parts in there) and causes ICEs during expansion
> (VIEW_CONVERT_EXPR from such OImode array to BLKmode BITINT_TYPE), so the
> following patch makes sure such arrays reflect the BLKmode of BITINT_TYPEs
> it is accessed with (if any).
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
So the issue is only manifesting during expansion? I think it would
be better to detect the specific issue (V_C_E from register to BLKmode)
in discover_nonconstant_array_refs_r and force the register argument
to stack?
> 2024-01-18 Jakub Jelinek <ja...@redhat.com>
>
> * gimple-lower-bitint.cc (gimple_lower_bitint): When creating
> array VAR_DECL for BITINT_TYPE SSA_NAMEs which have BLKmode, force
> DECL_MODE of those vars to be BLKmode as well.
>
> --- gcc/gimple-lower-bitint.cc.jj 2024-01-17 14:43:33.498961304 +0100
> +++ gcc/gimple-lower-bitint.cc 2024-01-17 14:50:50.252889131 +0100
> @@ -6348,7 +6348,15 @@ gimple_lower_bitint (void)
> tree s = ssa_name (i);
> int p = var_to_partition (large_huge.m_map, s);
> if (large_huge.m_vars[p] != NULL_TREE)
> - continue;
> + {
> + /* If BITINT_TYPE is BLKmode, make sure the underlying
> + variable is BLKmode as well. */
> + if (TYPE_MODE (TREE_TYPE (s)) == BLKmode
> + && VAR_P (large_huge.m_vars[p])
> + && DECL_MODE (large_huge.m_vars[p]) != BLKmode)
> + DECL_MODE (large_huge.m_vars[p]) = BLKmode;
> + continue;
> + }
> if (atype == NULL_TREE
> || !tree_int_cst_equal (TYPE_SIZE (atype),
> TYPE_SIZE (TREE_TYPE (s))))
> @@ -6359,6 +6367,11 @@ gimple_lower_bitint (void)
> }
> large_huge.m_vars[p] = create_tmp_var (atype, "bitint");
> mark_addressable (large_huge.m_vars[p]);
> + /* If BITINT_TYPE is BLKmode, make sure the underlying
> + variable is BLKmode as well. */
> + if (TYPE_MODE (TREE_TYPE (s)) == BLKmode
> + && DECL_MODE (large_huge.m_vars[p]) != BLKmode)
> + DECL_MODE (large_huge.m_vars[p]) = BLKmode;
> }
> }
>
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
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