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Re: [PATCH] -fsanitize=vptr instrumentation (take 2)
- From: Jason Merrill <jason at redhat dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: Alexey Samsonov <vonosmas at gmail dot com>, Marek Polacek <mpolacek at redhat dot com>, gcc-patches at gcc dot gnu dot org
- Date: Wed, 26 Nov 2014 11:18:11 -0500
- Subject: Re: [PATCH] -fsanitize=vptr instrumentation (take 2)
- Authentication-results: sourceware.org; auth=none
- References: <20140916145644 dot GZ17454 at tucnak dot redhat dot com> <54199A36 dot 1080604 at redhat dot com> <20141027161605 dot GX10376 at tucnak dot redhat dot com> <20141028124450 dot GJ10376 at tucnak dot redhat dot com>
On 10/28/2014 08:44 AM, Jakub Jelinek wrote:
+cp_ubsan_check_member_access_r (tree *stmt_p, int *walk_subtrees, void *data)
This function needs a longer comment about exactly what forms it's
trying to instrument.
+ /* T t; t.foo (); doesn't need instrumentation, if the type is known. */
+ if (is_addr
+ && TREE_CODE (op) == ADDR_EXPR
+ && DECL_P (TREE_OPERAND (op, 0))
+ && same_type_p (type,
+ TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (op, 0)))))
+ return NULL_TREE;
How do we know the decl's vptr hasn't been clobbered? This seems like
one of the optimizations we decided to drop.
+ if (TREE_CODE (base) == COMPONENT_REF
+ && DECL_ARTIFICIAL (TREE_OPERAND (base, 1)))
+ {
+ tree base2 = TREE_OPERAND (base, 0);
+ while (TREE_CODE (base2) == COMPONENT_REF
+ || TREE_CODE (base2) == ARRAY_REF
+ || TREE_CODE (base2) == ARRAY_RANGE_REF)
+ base2 = TREE_OPERAND (base2, 0);
+ if (TREE_CODE (base2) != INDIRECT_REF
+ && TREE_CODE (base2) != MEM_REF)
+ return;
+ }
+ else if (TREE_CODE (base) != INDIRECT_REF
+ && TREE_CODE (base) != MEM_REF)
+ return;
Why do you look through ARRAY_REF here? An element of an array is its
own complete object.
Jason