On Wed, 5 Dec 2012, Jakub Jelinek wrote:
> Hi!
>
> This patch tries to handle bitfield accesses as if it were writes/reads
> from the corresponding DECL_BIT_FIELD_REPRESENTATIVE.
> Richard, does it make sense this way (the code will take ADDR_EXPR
> of the COMPONENT_REF with the DECL_BIT_FIELD_REPRESENTATIVE and use
> the size of the representative if it decides to instrument it.
>
> Fixes the first 4 asan_test.C failures. Ok for trunk?
It makes sense apart from the address-taking - is this done early
enough to not disrupt aliasing / TREE_ADDRESSABLE? Thus, before
gimplifying?
Thanks,
Richard.
> 2012-12-05 Jakub Jelinek <ja...@redhat.com>
>
> * asan.c (instrument_derefs): Handle bitfield COMPONENT_REFs
> accesses as reads/writes to their DECL_BIT_FIELD_REPRESENTATIVE.
>
> --- gcc/asan.c.jj 2012-12-05 15:30:56.000000000 +0100
> +++ gcc/asan.c 2012-12-05 17:00:56.957641944 +0100
> @@ -792,9 +792,6 @@ instrument_derefs (gimple_stmt_iterator
> || (unsigned HOST_WIDE_INT) size_in_bytes - 1 >= 16)
> return;
>
> - /* For now just avoid instrumenting bit field acceses.
> - Fixing it is doable, but expected to be messy. */
> -
> HOST_WIDE_INT bitsize, bitpos;
> tree offset;
> enum machine_mode mode;
> @@ -803,7 +800,17 @@ instrument_derefs (gimple_stmt_iterator
> &mode, &unsignedp, &volatilep, false);
> if (bitpos % (size_in_bytes * BITS_PER_UNIT)
> || bitsize != size_in_bytes * BITS_PER_UNIT)
> - return;
> + {
> + if (TREE_CODE (t) == COMPONENT_REF
> + && DECL_BIT_FIELD_REPRESENTATIVE (TREE_OPERAND (t, 1)) != NULL_TREE)
> + {
> + tree repr = DECL_BIT_FIELD_REPRESENTATIVE (TREE_OPERAND (t, 1));
> + instrument_derefs (iter, build3 (COMPONENT_REF, TREE_TYPE (repr),
> + TREE_OPERAND (t, 0), repr,
> + NULL_TREE), location, is_store);
> + }
> + return;
> + }
>
> base = build_fold_addr_expr (t);
> build_check_stmt (location, base, iter, /*before_p=*/true,
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imend
