On Sun, 4 Dec 2011, Richard Guenther wrote:
> On Sat, Dec 3, 2011 at 7:56 PM, Richard Henderson <r...@redhat.com> wrote:
> > On 12/03/2011 06:30 AM, Richard Guenther wrote:
> >> Not if you look at the respective gimple level dependency routines
> >> in tree-ssa-alias.c, OTOH tree-data-ref.c simply refuses to handle
> >> volatile references at all.
> >
> > That's something we'd better fix, then, regardless of whether
> > some pass currently refuses to handle them.
>
> I'll prepare a patch.
Like the following.
Bootstrap/regtest pending on x86_64-unknown-linux-gnu.
Richard.
2011-12-05 Richard Guenther <rguent...@suse.de>
* tree-ssa-alias.h (struct ao_ref_s): Add volatile_p field.
* tree-ssa-alias.c (ao_ref_init): Initialize it.
(ao_ref_init_from_ptr_and_size): Likewise.
(refs_may_alias_p_1): Two volatile accesses conflict.
(ref_maybe_used_by_call_p_1): Likewise.
(call_may_clobber_ref_p_1): Likewise.
* tree-ssa-sccvn.c (ao_ref_init_from_vn_reference): Initialize
volatile_p field.
Index: gcc/tree-ssa-alias.h
===================================================================
*** gcc/tree-ssa-alias.h (revision 182001)
--- gcc/tree-ssa-alias.h (working copy)
*************** typedef struct ao_ref_s
*** 86,91 ****
--- 86,94 ----
/* The alias set of the base object or -1 if not yet computed. */
alias_set_type base_alias_set;
+
+ /* Whether the memory is considered a volatile access. */
+ bool volatile_p;
} ao_ref;
Index: gcc/tree-ssa-alias.c
===================================================================
*** gcc/tree-ssa-alias.c (revision 182001)
--- gcc/tree-ssa-alias.c (working copy)
*************** ao_ref_init (ao_ref *r, tree ref)
*** 456,461 ****
--- 456,462 ----
r->max_size = -1;
r->ref_alias_set = -1;
r->base_alias_set = -1;
+ r->volatile_p = ref ? TREE_THIS_VOLATILE (ref) : false;
}
/* Returns the base object of the memory reference *REF. */
*************** ao_ref_init_from_ptr_and_size (ao_ref *r
*** 525,530 ****
--- 526,532 ----
ref->max_size = ref->size = -1;
ref->ref_alias_set = 0;
ref->base_alias_set = 0;
+ ref->volatile_p = false;
}
/* Return 1 if TYPE1 and TYPE2 are to be considered equivalent for the
*************** refs_may_alias_p_1 (ao_ref *ref1, ao_ref
*** 1021,1026 ****
--- 1023,1033 ----
|| TREE_CODE (base2) == LABEL_DECL)
return true;
+ /* Two volatile accesses always conflict. */
+ if (ref1->volatile_p
+ && ref2->volatile_p)
+ return true;
+
/* Defer to simple offset based disambiguation if we have
references based on two decls. Do this before defering to
TBAA to handle must-alias cases in conformance with the
*************** ref_maybe_used_by_call_p_1 (gimple call,
*** 1144,1149 ****
--- 1151,1161 ----
if (!base)
return true;
+ /* A call that is not without side-effects might involve volatile
+ accesses and thus conflicts with all other volatile accesses. */
+ if (ref->volatile_p)
+ return true;
+
/* If the reference is based on a decl that is not aliased the call
cannot possibly use it. */
if (DECL_P (base)
*************** call_may_clobber_ref_p_1 (gimple call, a
*** 1477,1482 ****
--- 1489,1499 ----
|| CONSTANT_CLASS_P (base))
return false;
+ /* A call that is not without side-effects might involve volatile
+ accesses and thus conflicts with all other volatile accesses. */
+ if (ref->volatile_p)
+ return true;
+
/* If the reference is based on a decl that is not aliased the call
cannot possibly clobber it. */
if (DECL_P (base)
Index: gcc/tree-ssa-sccvn.c
===================================================================
*** gcc/tree-ssa-sccvn.c (revision 182001)
--- gcc/tree-ssa-sccvn.c (working copy)
*************** ao_ref_init_from_vn_reference (ao_ref *r
*** 918,923 ****
--- 918,925 ----
ref->base_alias_set = base_alias_set;
else
ref->base_alias_set = get_alias_set (base);
+ /* We discount volatiles from value-numbering elsewhere. */
+ ref->volatile_p = false;
return true;
}
