On Tue, 24 Sep 2013, Richard Biener wrote:
> On Tue, 24 Sep 2013, Jakub Jelinek wrote:
>
> > Hi!
> >
> > On Mon, Sep 23, 2013 at 05:26:13PM -0700, Cong Hou wrote:
> >
> > Missing ChangeLog entry.
> >
> > > --- gcc/testsuite/gcc.dg/alias-14.c (revision 0)
> > > +++ gcc/testsuite/gcc.dg/alias-14.c (revision 0)
> >
> > Vectorizer tests should go into gcc.dg/vect/ instead, or, if they are
> > for a single target (but there is no reason why this should be a single
> > target), into gcc.target/<target>/.
> >
> > > --- gcc/fold-const.c (revision 202662)
> > > +++ gcc/fold-const.c (working copy)
> > > @@ -2693,8 +2693,9 @@ operand_equal_p (const_tree arg0, const_
> > > && operand_equal_p (TYPE_SIZE (TREE_TYPE (arg0)),
> > > TYPE_SIZE (TREE_TYPE (arg1)), flags)))
> > > && types_compatible_p (TREE_TYPE (arg0), TREE_TYPE (arg1))
> > > - && (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg0, 1)))
> > > - == TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg1, 1))))
> > > + && types_compatible_p (
> > > + TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg0, 1))),
> > > + TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg1, 1))))
> > > && OP_SAME (0) && OP_SAME (1));
> >
> > This looks wrong. types_compatible_p will happily return true say
> > for unsigned long and unsigned long long types on x86_64, because
> > they are both integral types with the same precision, but the second
> > argument of MEM_REF contains aliasing information, where the distinction
> > between the two is important.
> > So, while == comparison of main variant is too strict, types_compatible_p
> > is too weak, so I guess you need to write a new predicate that will either
> > handle the == and a few special cases that are safe to be handled, or
> > look for what exactly we use the type of the second MEM_REF argument
> > and check those properties. We certainly need that
> > get_deref_alias_set_1 and get_deref_alias_set return the same values
> > for both the types, but whether that is the only information we are using,
> > not sure, CCing Richard.
>
> Using TYPE_MAIN_VARIANT is exactly correct - this is the best we
> can do that will work with all frontends. TYPE_MAIN_VARIANT
> guarantees that the alias-sets stay the same:
>
> /* If the innermost reference is a MEM_REF that has a
> conversion embedded treat it like a VIEW_CONVERT_EXPR above,
> using the memory access type for determining the alias-set. */
> if (TREE_CODE (inner) == MEM_REF
> && TYPE_MAIN_VARIANT (TREE_TYPE (inner))
> != TYPE_MAIN_VARIANT
> (TREE_TYPE (TREE_TYPE (TREE_OPERAND (inner, 1)))))
> return get_deref_alias_set (TREE_OPERAND (inner, 1));
>
> so we cannot change the compatibility checks without touching the
> alias-set deriving code. For the testcase in question we have
> MEM[(const int &)_7] vs. MEM[(int *)_7] and unfortunately pointer
> and reference types are not variant types.
>
> We also cannot easily resort to pointed-to types as our all-beloved
> ref-all qualification is on the pointer type rather than on the
> pointed-to type.
>
> But yes, we could implement a more complicated predicate
>
> bool
> alias_ptr_types_compatible_p (const_tree t1, const_tree t2)
> {
> t1 = TYPE_MAIN_VARIANT (t1);
> t2 = TYPE_MAIN_VARIANT (t2);
> if (t1 == t2)
> return true;
>
> if (TYPE_REF_CAN_ALIAS_ALL (t1)
> || TYPE_REF_CAN_ALIAS_ALL (t2))
> return false;
>
> return (TYPE_MAIN_VARIANT (TREE_TYPE (t1))
> == TYPE_MAIN_VARIANT (TREE_TYPE (t2)));
> }
>
> Note that the fold-const code in question is
>
> return ((TYPE_SIZE (TREE_TYPE (arg0)) == TYPE_SIZE (TREE_TYPE
> (arg1))
> || (TYPE_SIZE (TREE_TYPE (arg0))
> && TYPE_SIZE (TREE_TYPE (arg1))
> && operand_equal_p (TYPE_SIZE (TREE_TYPE (arg0)),
> TYPE_SIZE (TREE_TYPE (arg1)),
> flags)))
> && types_compatible_p (TREE_TYPE (arg0), TREE_TYPE
> (arg1))
> && (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg0,
> 1)))
> == TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg1,
> 1))))
> && OP_SAME (0) && OP_SAME (1));
>
> which you may notice uses types_compatible_p on the reference type
> which is at least suspicious as that can let through reference trees
> that will end up using different alias sets due to the stricter
> check in get_alias_set.
>
> So in addition to alias_ptr_types_compatible_p we may want to have
>
> bool
> reference_alias_ptr_types_compatible_p (const_tree t1, const_tree t2)
> {
> ...
> }
>
> abstracting this away for the actual reference trees (also noting
> that reference_alias_ptr_type isn't 1:1 following what get_alias_set
> does either).
>
> I will give this a try.
The following is an untested (well, the testcase from PR58513 is now
vectorized) patch doing that refactoring.
Richard.
Index: gcc/tree.c
===================================================================
*** gcc/tree.c (revision 202859)
--- gcc/tree.c (working copy)
*************** mem_ref_offset (const_tree t)
*** 4263,4286 ****
return tree_to_double_int (toff).sext (TYPE_PRECISION (TREE_TYPE (toff)));
}
- /* Return the pointer-type relevant for TBAA purposes from the
- gimple memory reference tree T. This is the type to be used for
- the offset operand of MEM_REF or TARGET_MEM_REF replacements of T. */
-
- tree
- reference_alias_ptr_type (const_tree t)
- {
- const_tree base = t;
- while (handled_component_p (base))
- base = TREE_OPERAND (base, 0);
- if (TREE_CODE (base) == MEM_REF)
- return TREE_TYPE (TREE_OPERAND (base, 1));
- else if (TREE_CODE (base) == TARGET_MEM_REF)
- return TREE_TYPE (TMR_OFFSET (base));
- else
- return build_pointer_type (TYPE_MAIN_VARIANT (TREE_TYPE (base)));
- }
-
/* Return an invariant ADDR_EXPR of type TYPE taking the address of BASE
offsetted by OFFSET units. */
--- 4263,4268 ----
Index: gcc/tree.h
===================================================================
*** gcc/tree.h (revision 202859)
--- gcc/tree.h (working copy)
*************** extern tree build_simple_mem_ref_loc (lo
*** 4345,4351 ****
#define build_simple_mem_ref(T)\
build_simple_mem_ref_loc (UNKNOWN_LOCATION, T)
extern double_int mem_ref_offset (const_tree);
- extern tree reference_alias_ptr_type (const_tree);
extern tree build_invariant_address (tree, tree, HOST_WIDE_INT);
extern tree constant_boolean_node (bool, tree);
extern tree div_if_zero_remainder (enum tree_code, const_tree, const_tree);
--- 4345,4350 ----
Index: gcc/alias.c
===================================================================
*** gcc/alias.c (revision 202859)
--- gcc/alias.c (working copy)
*************** component_uses_parent_alias_set (const_t
*** 547,552 ****
--- 547,564 ----
}
}
+
+ /* Return whether the pointer-type T effective for aliasing may
+ access everything and thus the reference has to be assigned
+ alias-set zero. */
+
+ static bool
+ ref_all_alias_ptr_type_p (const_tree t)
+ {
+ return (TREE_CODE (TREE_TYPE (t)) == VOID_TYPE
+ || TYPE_REF_CAN_ALIAS_ALL (t));
+ }
+
/* Return the alias set for the memory pointed to by T, which may be
either a type or an expression. Return -1 if there is nothing
special about dereferencing T. */
*************** component_uses_parent_alias_set (const_t
*** 554,564 ****
static alias_set_type
get_deref_alias_set_1 (tree t)
{
- /* If we're not doing any alias analysis, just assume everything
- aliases everything else. */
- if (!flag_strict_aliasing)
- return 0;
-
/* All we care about is the type. */
if (! TYPE_P (t))
t = TREE_TYPE (t);
--- 566,571 ----
*************** get_deref_alias_set_1 (tree t)
*** 566,573 ****
/* If we have an INDIRECT_REF via a void pointer, we don't
know anything about what that might alias. Likewise if the
pointer is marked that way. */
! if (TREE_CODE (TREE_TYPE (t)) == VOID_TYPE
! || TYPE_REF_CAN_ALIAS_ALL (t))
return 0;
return -1;
--- 573,579 ----
/* If we have an INDIRECT_REF via a void pointer, we don't
know anything about what that might alias. Likewise if the
pointer is marked that way. */
! if (ref_all_alias_ptr_type_p (t))
return 0;
return -1;
*************** get_deref_alias_set_1 (tree t)
*** 579,584 ****
--- 585,595 ----
alias_set_type
get_deref_alias_set (tree t)
{
+ /* If we're not doing any alias analysis, just assume everything
+ aliases everything else. */
+ if (!flag_strict_aliasing)
+ return 0;
+
alias_set_type set = get_deref_alias_set_1 (t);
/* Fall back to the alias-set of the pointed-to type. */
*************** get_deref_alias_set (tree t)
*** 592,597 ****
--- 603,698 ----
return set;
}
+ static tree
+ reference_alias_ptr_type_1 (tree *t)
+ {
+ tree inner;
+
+ /* Get the base object of the reference. */
+ inner = *t;
+ while (handled_component_p (inner))
+ {
+ /* If there is a VIEW_CONVERT_EXPR in the chain we cannot use
+ the type of any component references that wrap it to
+ determine the alias-set. */
+ if (TREE_CODE (inner) == VIEW_CONVERT_EXPR)
+ *t = TREE_OPERAND (inner, 0);
+ inner = TREE_OPERAND (inner, 0);
+ }
+
+ /* Handle pointer dereferences here, they can override the
+ alias-set. */
+ if (INDIRECT_REF_P (inner)
+ && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner, 0))))
+ return TREE_TYPE (TREE_OPERAND (inner, 0));
+ else if (TREE_CODE (inner) == TARGET_MEM_REF)
+ return TREE_TYPE (TMR_OFFSET (inner));
+ else if (TREE_CODE (inner) == MEM_REF
+ && ref_all_alias_ptr_type_p (TREE_TYPE (TREE_OPERAND (inner, 1))))
+ return TREE_TYPE (TREE_OPERAND (inner, 1));
+
+ /* If the innermost reference is a MEM_REF that has a
+ conversion embedded treat it like a VIEW_CONVERT_EXPR above,
+ using the memory access type for determining the alias-set. */
+ if (TREE_CODE (inner) == MEM_REF
+ && (TYPE_MAIN_VARIANT (TREE_TYPE (inner))
+ != TYPE_MAIN_VARIANT
+ (TREE_TYPE (TREE_TYPE (TREE_OPERAND (inner, 1))))))
+ return TREE_TYPE (TREE_OPERAND (inner, 1));
+
+ /* Otherwise, pick up the outermost object that we could have a pointer
+ to, processing conversions as above. */
+ /* ??? Ick, this is worse than quadratic! */
+ while (component_uses_parent_alias_set (*t))
+ {
+ *t = TREE_OPERAND (*t, 0);
+ STRIP_NOPS (*t);
+ }
+
+ return NULL_TREE;
+ }
+
+ /* Return the pointer-type relevant for TBAA purposes from the
+ gimple memory reference tree T. This is the type to be used for
+ the offset operand of MEM_REF or TARGET_MEM_REF replacements of T
+ and guarantees that get_alias_set will return the same alias
+ set for T and the replacement. */
+
+ tree
+ reference_alias_ptr_type (tree t)
+ {
+ tree ptype = reference_alias_ptr_type_1 (&t);
+ /* If there is a given pointer type for aliasing purposes, return it. */
+ if (ptype != NULL_TREE)
+ return ptype;
+
+ /* Otherwise build one from the outermost component reference we
+ may use. */
+ if (TREE_CODE (t) == MEM_REF
+ || TREE_CODE (t) == TARGET_MEM_REF)
+ return TREE_TYPE (TREE_OPERAND (t, 1));
+ else
+ return build_pointer_type (TYPE_MAIN_VARIANT (TREE_TYPE (t)));
+ }
+
+ /* Return whether the pointer-types T1 and T2 used to determine
+ two alias sets of two references will yield the same answer
+ from get_deref_alias_set. */
+
+ bool
+ alias_ptr_types_compatible_p (tree t1, tree t2)
+ {
+ if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
+ return true;
+
+ if (ref_all_alias_ptr_type_p (t1)
+ || ref_all_alias_ptr_type_p (t2))
+ return false;
+
+ return (TYPE_MAIN_VARIANT (TREE_TYPE (t1))
+ == TYPE_MAIN_VARIANT (TREE_TYPE (t2)));
+ }
+
/* Return the alias set for T, which may be either a type or an
expression. Call language-specific routine for help, if needed. */
*************** get_alias_set (tree t)
*** 615,622 ****
aren't types. */
if (! TYPE_P (t))
{
- tree inner;
-
/* Give the language a chance to do something with this tree
before we look at it. */
STRIP_NOPS (t);
--- 716,721 ----
*************** get_alias_set (tree t)
*** 624,674 ****
if (set != -1)
return set;
! /* Get the base object of the reference. */
! inner = t;
! while (handled_component_p (inner))
! {
! /* If there is a VIEW_CONVERT_EXPR in the chain we cannot use
! the type of any component references that wrap it to
! determine the alias-set. */
! if (TREE_CODE (inner) == VIEW_CONVERT_EXPR)
! t = TREE_OPERAND (inner, 0);
! inner = TREE_OPERAND (inner, 0);
! }
!
! /* Handle pointer dereferences here, they can override the
! alias-set. */
! if (INDIRECT_REF_P (inner))
! {
! set = get_deref_alias_set_1 (TREE_OPERAND (inner, 0));
! if (set != -1)
! return set;
! }
! else if (TREE_CODE (inner) == TARGET_MEM_REF)
! return get_deref_alias_set (TMR_OFFSET (inner));
! else if (TREE_CODE (inner) == MEM_REF)
! {
! set = get_deref_alias_set_1 (TREE_OPERAND (inner, 1));
! if (set != -1)
! return set;
! }
!
! /* If the innermost reference is a MEM_REF that has a
! conversion embedded treat it like a VIEW_CONVERT_EXPR above,
! using the memory access type for determining the alias-set. */
! if (TREE_CODE (inner) == MEM_REF
! && TYPE_MAIN_VARIANT (TREE_TYPE (inner))
! != TYPE_MAIN_VARIANT
! (TREE_TYPE (TREE_TYPE (TREE_OPERAND (inner, 1)))))
! return get_deref_alias_set (TREE_OPERAND (inner, 1));
!
! /* Otherwise, pick up the outermost object that we could have a pointer
! to, processing conversions as above. */
! while (component_uses_parent_alias_set (t))
! {
! t = TREE_OPERAND (t, 0);
! STRIP_NOPS (t);
! }
/* If we've already determined the alias set for a decl, just return
it. This is necessary for C++ anonymous unions, whose component
--- 723,733 ----
if (set != -1)
return set;
! /* Get the alias pointer-type to use or the outermost object
! that we could have a pointer to. */
! tree ptype = reference_alias_ptr_type_1 (&t);
! if (ptype != NULL)
! return get_deref_alias_set (ptype);
/* If we've already determined the alias set for a decl, just return
it. This is necessary for C++ anonymous unions, whose component
Index: gcc/alias.h
===================================================================
*** gcc/alias.h (revision 202859)
--- gcc/alias.h (working copy)
*************** extern int alias_sets_conflict_p (alias_
*** 41,46 ****
--- 41,48 ----
extern int alias_sets_must_conflict_p (alias_set_type, alias_set_type);
extern int objects_must_conflict_p (tree, tree);
extern int nonoverlapping_memrefs_p (const_rtx, const_rtx, bool);
+ tree reference_alias_ptr_type (tree);
+ bool alias_ptr_types_compatible_p (tree, tree);
/* This alias set can be used to force a memory to conflict with all
other memories, creating a barrier across which no memory reference
Index: gcc/fold-const.c
===================================================================
*** gcc/fold-const.c (revision 202859)
--- gcc/fold-const.c (working copy)
*************** operand_equal_p (const_tree arg0, const_
*** 2693,2700 ****
&& operand_equal_p (TYPE_SIZE (TREE_TYPE (arg0)),
TYPE_SIZE (TREE_TYPE (arg1)),
flags)))
&& types_compatible_p (TREE_TYPE (arg0), TREE_TYPE (arg1))
! && (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg0, 1)))
! == TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (arg1, 1))))
&& OP_SAME (0) && OP_SAME (1));
case ARRAY_REF:
--- 2693,2701 ----
&& operand_equal_p (TYPE_SIZE (TREE_TYPE (arg0)),
TYPE_SIZE (TREE_TYPE (arg1)),
flags)))
&& types_compatible_p (TREE_TYPE (arg0), TREE_TYPE (arg1))
! && alias_ptr_types_compatible_p
! (TREE_TYPE (TREE_OPERAND (arg0, 1)),
! TREE_TYPE (TREE_OPERAND (arg1, 1)))
&& OP_SAME (0) && OP_SAME (1));
case ARRAY_REF:
