On Fri, 31 May 2019, Jan Hubicka wrote:
> 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)
'path', but I think type_has_components_p would be a better fit?
> +{
> + 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)))
extra parens around the call here and below.
OK with all these issues fixed.
Richard.
> && (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)))
> {
>
--
Richard Biener <rguent...@suse.de>
SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany;
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah; HRB 21284 (AG Nürnberg)
