Hi
in most common cases we have access paths that ends by read/write of a
non-composite type. When aliasing_component_refs_p finds no match in
the acccess path it asks alias oracle if the one alias set is subset of
other to figure out whether one access path can be extended to the
other.
This is unnecessarily conservatie especially for pointers where we say tru
for
foo->ptr
bar->ptr
where foo and bar are two structures containing pointers of different type.
This patch bypasses the alis oracle check for non-composite types. Along with
yesterday patch and patch to handle pointers in types_same_for_tbaa_p we now
get:
refs_may_alias_p: 3019081 disambiguations, 3318862 queries
ref_maybe_used_by_call_p: 7112 disambiguations, 3044693 queries
call_may_clobber_ref_p: 817 disambiguations, 817 queries
aliasing_component_ref_p: 2259 disambiguations, 17881 queries
TBAA oracle: 1421561 disambiguations 2922798 queries
552636 are in alias set 0
569791 queries asked about the same object
0 queries asked about the same alias set
0 access volatile
260727 are dependent in the DAG
118083 are aritificially in conflict with void *
Compared to:
refs_may_alias_p: 3013678 disambiguations, 3314059 queries
ref_maybe_used_by_call_p: 7112 disambiguations, 3039278 queries
call_may_clobber_ref_p: 817 disambiguations, 817 queries
aliasing_component_ref_p: 636 disambiguations, 15844 queries
TBAA oracle: 1417999 disambiguations 2915696 queries
552182 are in alias set 0
569795 queries asked about the same object
0 queries asked about the same alias set
0 access volatile
259437 are dependent in the DAG
116283 are aritificially in conflict with void *
(my original prototype patch did about 14000 disambiguations out of 40000
querries while passing testuite, so we are slowly getting closer).
I have a testcase but it depends on same_type_for_tbaa not giving up on
pointers, so I plan to send it as a followup.
Bootstrapped/regtested x86_64-linux (all languages<O), OK?
* tree-ssa-alias.c (access_patch_may_continue_p): New function.
(aliasing_component_refs_p): Use it.
Index: tree-ssa-alias.c
===================================================================
--- tree-ssa-alias.c (revision 271747)
@@ -822,6 +842,16 @@ same_type_for_tbaa (tree type1, tree typ
return 0;
}
+/* Return true if TYPE is a composite type (i.e. we may apply one of handled
+ components on it). */
+
+static bool
+access_patch_may_continue_p (tree type)
+{
+ return AGGREGATE_TYPE_P (type) || VECTOR_TYPE_P (type)
+ || TREE_CODE (type) == COMPLEX_TYPE;
+}
+
/* Determine if the two component references REF1 and REF2 which are
based on access types TYPE1 and TYPE2 and of which at least one is based
on an indirect reference may alias. REF2 is the only one that can
@@ -965,6 +1028,7 @@ aliasing_component_refs_p (tree ref1,
if there is no B2 in the tail of path1 and no B1 on the
tail of path2. */
if (compare_type_sizes (TREE_TYPE (ref2), type1) >= 0
+ && (access_patch_may_continue_p (TREE_TYPE (ref2)))
&& (base1_alias_set == ref2_alias_set
|| alias_set_subset_of (base1_alias_set, ref2_alias_set)))
{
@@ -974,6 +1038,7 @@ aliasing_component_refs_p (tree ref1,
/* If this is ptr vs. decl then we know there is no ptr ... decl path. */
if (!ref2_is_decl
&& compare_type_sizes (TREE_TYPE (ref1), type2) >= 0
+ && (access_patch_may_continue_p (TREE_TYPE (ref1)))
&& (base2_alias_set == ref1_alias_set
|| alias_set_subset_of (base2_alias_set, ref1_alias_set)))
{
