On Fri, Aug 4, 2017 at 11:28 AM, Richard Sandiford <richard.sandif...@linaro.org> wrote: > Richard Biener <richard.guent...@gmail.com> writes: >> On Thu, Jul 27, 2017 at 2:19 PM, Richard Sandiford >> <richard.sandif...@linaro.org> wrote: >>> Richard Sandiford <richard.sandif...@linaro.org> writes: >>>> Eric Botcazou <ebotca...@adacore.com> writes: >>>>> [Sorry for missing the previous messages] >>>>> >>>>>> Thanks. Just been retesting, and I think I must have forgotten >>>>>> to include Ada last time. It turns out that the patch causes a dg-scan >>>>>> regression in gnat.dg/vect17.adb, because we now think that if the >>>>>> array RECORD_TYPEs *do* alias in: >>>>>> >>>>>> procedure Add (X, Y : aliased Sarray; R : aliased out Sarray) is >>>>>> begin >>>>>> for I in Sarray'Range loop >>>>>> R(I) := X(I) + Y(I); >>>>>> end loop; >>>>>> end; >>>>>> >>>>>> then the dependence distance must be zero. Eric, does that hold true >>>>>> for Ada? I.e. if X and R (or Y and R) alias, must it be the case that >>>>>> X(I) can only alias R(I) and not for example R(I-1) or R(I+1)? >>>>> >>>>> Yes, I'd think so (even without the artificial RECORD_TYPE around >> the arrays). >>>> >>>> Good! >>>> >>>>>> 2017-06-07 Richard Sandiford <richard.sandif...@linaro.org> >>>>>> >>>>>> gcc/testsuite/ >>>>>> * gnat.dg/vect17.ads (Sarray): Increase range to 1 .. 5. >>>>>> * gnat.dg/vect17.adb (Add): Create a dependence distance of 1 >>>>>> when X = R or Y = R. >>>>> >>>>> I think that you need to modify vect15 and vect16 the same way. >>>> >>>> Ah, yeah. And doing that shows that I'd not handled safelen for >>>> DDR_COULD_BE_INDEPENDENT_P. I've fixed that locally. >>>> >>>> How does this look? Tested on x86_64-linux-gnu both without the >>>> vectoriser changes and with the fixed vectoriser patch. >>> >>> Here's a version of the patch that handles safelen. I split the >>> handling out into a new function (vect_analyze_possibly_independent_ddr) >>> since it was getting too big to do inline. >>> >>> Tested on aarch64-linux-gnu and x86_64-linux-gnu. OK to install? >> >> Ok. > > Thanks! > >> Did you check whether BB vectorization is affected? See >> vect_slp_analyze_instance_dependence >> and friends. It's quite conservative but given the prefetching change >> I wonder if we need >> to rule out DDR_COULD_BE_INDEPENDENT_P? > > I think it should be OK. When DDR_COULD_BE_INDEPENDENT_P is set, > we've effectively changed from DDR_ARE_DEPENDENT == chrec_dont_know > to a conservatively-correct distance vector. It looks like > vect_slp_analyze_data_ref_dependence handles both cases in the > same way (by returning true).
Yes. Could be improved of course. Thanks for double-checking. Richard. > Thanks, > Richard > >> >> Thanks, >> Richard. >> >>> Thanks, >>> Richard >>> >>> >>> 2017-07-27 Richard Sandiford <richard.sandif...@linaro.org> >>> >>> gcc/ >>> * tree-data-ref.h (subscript): Add access_fn field. >>> (data_dependence_relation): Add could_be_independent_p. >>> (SUB_ACCESS_FN, DDR_COULD_BE_INDEPENDENT_P): New macros. >>> (same_access_functions): Move to tree-data-ref.c. >>> * tree-data-ref.c (ref_contains_union_access_p): New function. >>> (access_fn_component_p): Likewise. >>> (access_fn_components_comparable_p): Likewise. >>> (dr_analyze_indices): Add a reference to access_fn_component_p. >>> (dump_data_dependence_relation): Use SUB_ACCESS_FN instead of >>> DR_ACCESS_FN. >>> (constant_access_functions): Likewise. >>> (add_other_self_distances): Likewise. >>> (same_access_functions): Likewise. (Moved from tree-data-ref.h.) >>> (initialize_data_dependence_relation): Use XCNEW and remove >>> explicit zeroing of DDR_REVERSED_P. Look for a subsequence >>> of access functions that have the same type. Allow the >>> subsequence to end with different bases in some circumstances. >>> Record the chosen access functions in SUB_ACCESS_FN. >>> (build_classic_dist_vector_1): Replace ddr_a and ddr_b with >>> a_index and b_index. Use SUB_ACCESS_FN instead of DR_ACCESS_FN. >>> (subscript_dependence_tester_1): Likewise dra and drb. >>> (build_classic_dist_vector): Update calls accordingly. >>> (subscript_dependence_tester): Likewise. >>> * tree-ssa-loop-prefetch.c (determine_loop_nest_reuse): Check >>> DDR_COULD_BE_INDEPENDENT_P. >>> * tree-vectorizer.h (LOOP_REQUIRES_VERSIONING_FOR_ALIAS): Test >>> comp_alias_ddrs instead of may_alias_ddrs. >>> * tree-vect-data-refs.c (vect_analyze_possibly_independent_ddr): >>> New function. >>> (vect_analyze_data_ref_dependence): Use it if >>> DDR_COULD_BE_INDEPENDENT_P, but fall back to using the recorded >>> distance vectors if that fails. >>> (dependence_distance_ge_vf): New function. >>> (vect_prune_runtime_alias_test_list): Use it. Don't clear >>> LOOP_VINFO_MAY_ALIAS_DDRS. >>> >>> gcc/testsuite/ >>> * gcc.dg/vect/vect-alias-check-3.c: New test. >>> * gcc.dg/vect/vect-alias-check-4.c: Likewise. >>> * gcc.dg/vect/vect-alias-check-5.c: Likewise. >>> >>> Index: gcc/tree-data-ref.h >>> =================================================================== >>> --- gcc/tree-data-ref.h 2017-07-27 13:10:29.620045506 +0100 >>> +++ gcc/tree-data-ref.h 2017-07-27 13:10:33.023912613 +0100 >>> @@ -260,6 +260,9 @@ struct conflict_function >>> >>> struct subscript >>> { >>> + /* The access functions of the two references. */ >>> + tree access_fn[2]; >>> + >>> /* A description of the iterations for which the elements are >>> accessed twice. */ >>> conflict_function *conflicting_iterations_in_a; >>> @@ -278,6 +281,7 @@ struct subscript >>> >>> typedef struct subscript *subscript_p; >>> >>> +#define SUB_ACCESS_FN(SUB, I) (SUB)->access_fn[I] >>> #define SUB_CONFLICTS_IN_A(SUB) (SUB)->conflicting_iterations_in_a >>> #define SUB_CONFLICTS_IN_B(SUB) (SUB)->conflicting_iterations_in_b >>> #define SUB_LAST_CONFLICT(SUB) (SUB)->last_conflict >>> @@ -333,6 +337,33 @@ struct data_dependence_relation >>> /* Set to true when the dependence relation is on the same data >>> access. */ >>> bool self_reference_p; >>> + >>> + /* True if the dependence described is conservatively correct rather >>> + than exact, and if it is still possible for the accesses to be >>> + conditionally independent. For example, the a and b references in: >>> + >>> + struct s *a, *b; >>> + for (int i = 0; i < n; ++i) >>> + a->f[i] += b->f[i]; >>> + >>> + conservatively have a distance vector of (0), for the case in which >>> + a == b, but the accesses are independent if a != b. Similarly, >>> + the a and b references in: >>> + >>> + struct s *a, *b; >>> + for (int i = 0; i < n; ++i) >>> + a[0].f[i] += b[i].f[i]; >>> + >>> + conservatively have a distance vector of (0), but they are indepenent >>> + when a != b + i. In contrast, the references in: >>> + >>> + struct s *a; >>> + for (int i = 0; i < n; ++i) >>> + a->f[i] += a->f[i]; >>> + >>> + have the same distance vector of (0), but the accesses can never be >>> + independent. */ >>> + bool could_be_independent_p; >>> }; >>> >>> typedef struct data_dependence_relation *ddr_p; >>> @@ -363,6 +394,7 @@ #define DDR_DIR_VECT(DDR, I) \ >>> #define DDR_DIST_VECT(DDR, I) \ >>> DDR_DIST_VECTS (DDR)[I] >>> #define DDR_REVERSED_P(DDR) (DDR)->reversed_p >>> +#define DDR_COULD_BE_INDEPENDENT_P(DDR) (DDR)->could_be_independent_p >>> >>> >>> bool dr_analyze_innermost (innermost_loop_behavior *, tree, struct loop *); >>> @@ -457,22 +489,6 @@ same_data_refs (data_reference_p a, data >>> return false; >>> >>> return true; >>> -} >>> - >>> -/* Return true when the DDR contains two data references that have the >>> - same access functions. */ >>> - >>> -static inline bool >>> -same_access_functions (const struct data_dependence_relation *ddr) >>> -{ >>> - unsigned i; >>> - >>> - for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++) >>> - if (!eq_evolutions_p (DR_ACCESS_FN (DDR_A (ddr), i), >>> - DR_ACCESS_FN (DDR_B (ddr), i))) >>> - return false; >>> - >>> - return true; >>> } >>> >>> /* Returns true when all the dependences are computable. */ >>> Index: gcc/tree-data-ref.c >>> =================================================================== >>> --- gcc/tree-data-ref.c 2017-07-27 13:10:29.620045506 +0100 >>> +++ gcc/tree-data-ref.c 2017-07-27 13:10:33.023912613 +0100 >>> @@ -124,8 +124,7 @@ Software Foundation; either version 3, o >>> } dependence_stats; >>> >>> static bool subscript_dependence_tester_1 (struct data_dependence_relation >>> *, >>> - struct data_reference *, >>> - struct data_reference *, >>> + unsigned int, unsigned int, >>> struct loop *); >>> /* Returns true iff A divides B. */ >>> >>> @@ -145,6 +144,21 @@ int_divides_p (int a, int b) >>> return ((b % a) == 0); >>> } >>> >>> +/* Return true if reference REF contains a union access. */ >>> + >>> +static bool >>> +ref_contains_union_access_p (tree ref) >>> +{ >>> + while (handled_component_p (ref)) >>> + { >>> + ref = TREE_OPERAND (ref, 0); >>> + if (TREE_CODE (TREE_TYPE (ref)) == UNION_TYPE >>> + || TREE_CODE (TREE_TYPE (ref)) == QUAL_UNION_TYPE) >>> + return true; >>> + } >>> + return false; >>> +} >>> + >>> >>> >>> /* Dump into FILE all the data references from DATAREFS. */ >>> @@ -434,13 +448,14 @@ dump_data_dependence_relation (FILE *out >>> unsigned int i; >>> struct loop *loopi; >>> >>> - for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++) >>> + subscript *sub; >>> + FOR_EACH_VEC_ELT (DDR_SUBSCRIPTS (ddr), i, sub) >>> { >>> fprintf (outf, " access_fn_A: "); >>> - print_generic_stmt (outf, DR_ACCESS_FN (dra, i)); >>> + print_generic_stmt (outf, SUB_ACCESS_FN (sub, 0)); >>> fprintf (outf, " access_fn_B: "); >>> - print_generic_stmt (outf, DR_ACCESS_FN (drb, i)); >>> - dump_subscript (outf, DDR_SUBSCRIPT (ddr, i)); >>> + print_generic_stmt (outf, SUB_ACCESS_FN (sub, 1)); >>> + dump_subscript (outf, sub); >>> } >>> >>> fprintf (outf, " inner loop index: %d\n", DDR_INNER_LOOP (ddr)); >>> @@ -920,6 +935,27 @@ dr_analyze_innermost (innermost_loop_beh >>> return true; >>> } >>> >>> +/* Return true if OP is a valid component reference for a DR access >>> + function. This accepts a subset of what handled_component_p accepts. >>> */ >>> + >>> +static bool >>> +access_fn_component_p (tree op) >>> +{ >>> + switch (TREE_CODE (op)) >>> + { >>> + case REALPART_EXPR: >>> + case IMAGPART_EXPR: >>> + case ARRAY_REF: >>> + return true; >>> + >>> + case COMPONENT_REF: >>> + return TREE_CODE (TREE_TYPE (TREE_OPERAND (op, 0))) == RECORD_TYPE; >>> + >>> + default: >>> + return false; >>> + } >>> +} >>> + >>> /* Determines the base object and the list of indices of memory reference >>> DR, analyzed in LOOP and instantiated in loop nest NEST. */ >>> >>> @@ -957,7 +993,9 @@ dr_analyze_indices (struct data_referenc >>> access_fns.safe_push (integer_one_node); >>> } >>> >>> - /* Analyze access functions of dimensions we know to be independent. */ >>> + /* Analyze access functions of dimensions we know to be independent. >>> + The list of component references handled here should be kept in >>> + sync with access_fn_component_p. */ >>> while (handled_component_p (ref)) >>> { >>> if (TREE_CODE (ref) == ARRAY_REF) >>> @@ -2148,6 +2186,38 @@ dr_may_alias_p (const struct data_refere >>> return refs_may_alias_p (addr_a, addr_b); >>> } >>> >>> +/* REF_A and REF_B both satisfy access_fn_component_p. Return true >>> + if it is meaningful to compare their associated access functions >>> + when checking for dependencies. */ >>> + >>> +static bool >>> +access_fn_components_comparable_p (tree ref_a, tree ref_b) >>> +{ >>> + /* Allow pairs of component refs from the following sets: >>> + >>> + { REALPART_EXPR, IMAGPART_EXPR } >>> + { COMPONENT_REF } >>> + { ARRAY_REF }. */ >>> + tree_code code_a = TREE_CODE (ref_a); >>> + tree_code code_b = TREE_CODE (ref_b); >>> + if (code_a == IMAGPART_EXPR) >>> + code_a = REALPART_EXPR; >>> + if (code_b == IMAGPART_EXPR) >>> + code_b = REALPART_EXPR; >>> + if (code_a != code_b) >>> + return false; >>> + >>> + if (TREE_CODE (ref_a) == COMPONENT_REF) >>> + /* ??? We cannot simply use the type of operand #0 of the refs here as >>> + the Fortran compiler smuggles type punning into COMPONENT_REFs. >>> + Use the DECL_CONTEXT of the FIELD_DECLs instead. */ >>> + return (DECL_CONTEXT (TREE_OPERAND (ref_a, 1)) >>> + == DECL_CONTEXT (TREE_OPERAND (ref_b, 1))); >>> + >>> + return types_compatible_p (TREE_TYPE (TREE_OPERAND (ref_a, 0)), >>> + TREE_TYPE (TREE_OPERAND (ref_b, 0))); >>> +} >>> + >>> /* Initialize a data dependence relation between data accesses A and >>> B. NB_LOOPS is the number of loops surrounding the references: the >>> size of the classic distance/direction vectors. */ >>> @@ -2160,11 +2230,10 @@ initialize_data_dependence_relation (str >>> struct data_dependence_relation *res; >>> unsigned int i; >>> >>> - res = XNEW (struct data_dependence_relation); >>> + res = XCNEW (struct data_dependence_relation); >>> DDR_A (res) = a; >>> DDR_B (res) = b; >>> DDR_LOOP_NEST (res).create (0); >>> - DDR_REVERSED_P (res) = false; >>> DDR_SUBSCRIPTS (res).create (0); >>> DDR_DIR_VECTS (res).create (0); >>> DDR_DIST_VECTS (res).create (0); >>> @@ -2182,82 +2251,277 @@ initialize_data_dependence_relation (str >>> return res; >>> } >>> >>> - /* The case where the references are exactly the same. */ >>> - if (operand_equal_p (DR_REF (a), DR_REF (b), 0)) >>> + unsigned int num_dimensions_a = DR_NUM_DIMENSIONS (a); >>> + unsigned int num_dimensions_b = DR_NUM_DIMENSIONS (b); >>> + if (num_dimensions_a == 0 || num_dimensions_b == 0) >>> { >>> - if ((loop_nest.exists () >>> - && !object_address_invariant_in_loop_p (loop_nest[0], >>> - DR_BASE_OBJECT (a))) >>> - || DR_NUM_DIMENSIONS (a) == 0) >>> + DDR_ARE_DEPENDENT (res) = chrec_dont_know; >>> + return res; >>> + } >>> + >>> + /* For unconstrained bases, the root (highest-indexed) subscript >>> + describes a variation in the base of the original DR_REF rather >>> + than a component access. We have no type that accurately describes >>> + the new DR_BASE_OBJECT (whose TREE_TYPE describes the type *after* >>> + applying this subscript) so limit the search to the last real >>> + component access. >>> + >>> + E.g. for: >>> + >>> + void >>> + f (int a[][8], int b[][8]) >>> + { >>> + for (int i = 0; i < 8; ++i) >>> + a[i * 2][0] = b[i][0]; >>> + } >>> + >>> + the a and b accesses have a single ARRAY_REF component reference [0] >>> + but have two subscripts. */ >>> + if (DR_UNCONSTRAINED_BASE (a)) >>> + num_dimensions_a -= 1; >>> + if (DR_UNCONSTRAINED_BASE (b)) >>> + num_dimensions_b -= 1; >>> + >>> + /* These structures describe sequences of component references in >>> + DR_REF (A) and DR_REF (B). Each component reference is tied to a >>> + specific access function. */ >>> + struct { >>> + /* The sequence starts at DR_ACCESS_FN (A, START_A) of A and >>> + DR_ACCESS_FN (B, START_B) of B (inclusive) and extends to higher >>> + indices. In C notation, these are the indices of the rightmost >>> + component references; e.g. for a sequence .b.c.d, the start >>> + index is for .d. */ >>> + unsigned int start_a; >>> + unsigned int start_b; >>> + >>> + /* The sequence contains LENGTH consecutive access functions from >>> + each DR. */ >>> + unsigned int length; >>> + >>> + /* The enclosing objects for the A and B sequences respectively, >>> + i.e. the objects to which DR_ACCESS_FN (A, START_A + LENGTH - 1) >>> + and DR_ACCESS_FN (B, START_B + LENGTH - 1) are applied. */ >>> + tree object_a; >>> + tree object_b; >>> + } full_seq = {}, struct_seq = {}; >>> + >>> + /* Before each iteration of the loop: >>> + >>> + - REF_A is what you get after applying DR_ACCESS_FN (A, INDEX_A) and >>> + - REF_B is what you get after applying DR_ACCESS_FN (B, INDEX_B). */ >>> + unsigned int index_a = 0; >>> + unsigned int index_b = 0; >>> + tree ref_a = DR_REF (a); >>> + tree ref_b = DR_REF (b); >>> + >>> + /* Now walk the component references from the final DR_REFs back up to >>> + the enclosing base objects. Each component reference corresponds >>> + to one access function in the DR, with access function 0 being for >>> + the final DR_REF and the highest-indexed access function being the >>> + one that is applied to the base of the DR. >>> + >>> + Look for a sequence of component references whose access functions >>> + are comparable (see access_fn_components_comparable_p). If more >>> + than one such sequence exists, pick the one nearest the base >>> + (which is the leftmost sequence in C notation). Store this sequence >>> + in FULL_SEQ. >>> + >>> + For example, if we have: >>> + >>> + struct foo { struct bar s; ... } (*a)[10], (*b)[10]; >>> + >>> + A: a[0][i].s.c.d >>> + B: __real b[0][i].s.e[i].f >>> + >>> + (where d is the same type as the real component of f) then the access >>> + functions would be: >>> + >>> + 0 1 2 3 >>> + A: .d .c .s [i] >>> + >>> + 0 1 2 3 4 5 >>> + B: __real .f [i] .e .s [i] >>> + >>> + The A0/B2 column isn't comparable, since .d is a COMPONENT_REF >>> + and [i] is an ARRAY_REF. However, the A1/B3 column contains two >>> + COMPONENT_REF accesses for struct bar, so is comparable. Likewise >>> + the A2/B4 column contains two COMPONENT_REF accesses for struct foo, >>> + so is comparable. The A3/B5 column contains two ARRAY_REFs that >>> + index foo[10] arrays, so is again comparable. The sequence is >>> + therefore: >>> + >>> + A: [1, 3] (i.e. [i].s.c) >>> + B: [3, 5] (i.e. [i].s.e) >>> + >>> + Also look for sequences of component references whose access >>> + functions are comparable and whose enclosing objects have the same >>> + RECORD_TYPE. Store this sequence in STRUCT_SEQ. In the above >>> + example, STRUCT_SEQ would be: >>> + >>> + A: [1, 2] (i.e. s.c) >>> + B: [3, 4] (i.e. s.e) */ >>> + while (index_a < num_dimensions_a && index_b < num_dimensions_b) >>> + { >>> + /* REF_A and REF_B must be one of the component access types >>> + allowed by dr_analyze_indices. */ >>> + gcc_checking_assert (access_fn_component_p (ref_a)); >>> + gcc_checking_assert (access_fn_component_p (ref_b)); >>> + >>> + /* Get the immediately-enclosing objects for REF_A and REF_B, >>> + i.e. the references *before* applying DR_ACCESS_FN (A, INDEX_A) >>> + and DR_ACCESS_FN (B, INDEX_B). */ >>> + tree object_a = TREE_OPERAND (ref_a, 0); >>> + tree object_b = TREE_OPERAND (ref_b, 0); >>> + >>> + tree type_a = TREE_TYPE (object_a); >>> + tree type_b = TREE_TYPE (object_b); >>> + if (access_fn_components_comparable_p (ref_a, ref_b)) >>> + { >>> + /* This pair of component accesses is comparable for dependence >>> + analysis, so we can include DR_ACCESS_FN (A, INDEX_A) and >>> + DR_ACCESS_FN (B, INDEX_B) in the sequence. */ >>> + if (full_seq.start_a + full_seq.length != index_a >>> + || full_seq.start_b + full_seq.length != index_b) >>> + { >>> + /* The accesses don't extend the current sequence, >>> + so start a new one here. */ >>> + full_seq.start_a = index_a; >>> + full_seq.start_b = index_b; >>> + full_seq.length = 0; >>> + } >>> + >>> + /* Add this pair of references to the sequence. */ >>> + full_seq.length += 1; >>> + full_seq.object_a = object_a; >>> + full_seq.object_b = object_b; >>> + >>> + /* If the enclosing objects are structures (and thus have the >>> + same RECORD_TYPE), record the new sequence in STRUCT_SEQ. */ >>> + if (TREE_CODE (type_a) == RECORD_TYPE) >>> + struct_seq = full_seq; >>> + >>> + /* Move to the next containing reference for both A and B. */ >>> + ref_a = object_a; >>> + ref_b = object_b; >>> + index_a += 1; >>> + index_b += 1; >>> + continue; >>> + } >>> + >>> + /* Try to approach equal type sizes. */ >>> + if (!COMPLETE_TYPE_P (type_a) >>> + || !COMPLETE_TYPE_P (type_b) >>> + || !tree_fits_uhwi_p (TYPE_SIZE_UNIT (type_a)) >>> + || !tree_fits_uhwi_p (TYPE_SIZE_UNIT (type_b))) >>> + break; >>> + >>> + unsigned HOST_WIDE_INT size_a = tree_to_uhwi (TYPE_SIZE_UNIT >>> (type_a)); >>> + unsigned HOST_WIDE_INT size_b = tree_to_uhwi (TYPE_SIZE_UNIT >>> (type_b)); >>> + if (size_a <= size_b) >>> { >>> - DDR_ARE_DEPENDENT (res) = chrec_dont_know; >>> - return res; >>> + index_a += 1; >>> + ref_a = object_a; >>> + } >>> + if (size_b <= size_a) >>> + { >>> + index_b += 1; >>> + ref_b = object_b; >>> } >>> - DDR_AFFINE_P (res) = true; >>> - DDR_ARE_DEPENDENT (res) = NULL_TREE; >>> - DDR_SUBSCRIPTS (res).create (DR_NUM_DIMENSIONS (a)); >>> - DDR_LOOP_NEST (res) = loop_nest; >>> - DDR_INNER_LOOP (res) = 0; >>> - DDR_SELF_REFERENCE (res) = true; >>> - for (i = 0; i < DR_NUM_DIMENSIONS (a); i++) >>> - { >>> - struct subscript *subscript; >>> - >>> - subscript = XNEW (struct subscript); >>> - SUB_CONFLICTS_IN_A (subscript) = conflict_fn_not_known (); >>> - SUB_CONFLICTS_IN_B (subscript) = conflict_fn_not_known (); >>> - SUB_LAST_CONFLICT (subscript) = chrec_dont_know; >>> - SUB_DISTANCE (subscript) = chrec_dont_know; >>> - DDR_SUBSCRIPTS (res).safe_push (subscript); >>> - } >>> - return res; >>> } >>> >>> - /* If the references do not access the same object, we do not know >>> - whether they alias or not. We do not care about TBAA or alignment >>> - info so we can use OEP_ADDRESS_OF to avoid false negatives. >>> - But the accesses have to use compatible types as otherwise the >>> - built indices would not match. */ >>> - if (!operand_equal_p (DR_BASE_OBJECT (a), DR_BASE_OBJECT (b), >> OEP_ADDRESS_OF) >>> - || !types_compatible_p (TREE_TYPE (DR_BASE_OBJECT (a)), >>> - TREE_TYPE (DR_BASE_OBJECT (b)))) >>> + /* See whether FULL_SEQ ends at the base and whether the two bases >>> + are equal. We do not care about TBAA or alignment info so we can >>> + use OEP_ADDRESS_OF to avoid false negatives. */ >>> + tree base_a = DR_BASE_OBJECT (a); >>> + tree base_b = DR_BASE_OBJECT (b); >>> + bool same_base_p = (full_seq.start_a + full_seq.length == >>> num_dimensions_a >>> + && full_seq.start_b + full_seq.length == num_dimensions_b >>> + && DR_UNCONSTRAINED_BASE (a) == DR_UNCONSTRAINED_BASE (b) >>> + && operand_equal_p (base_a, base_b, OEP_ADDRESS_OF) >>> + && types_compatible_p (TREE_TYPE (base_a), >>> + TREE_TYPE (base_b)) >>> + && (!loop_nest.exists () >>> + || (object_address_invariant_in_loop_p >>> + (loop_nest[0], base_a)))); >>> + >>> + /* If the bases are the same, we can include the base variation too. >>> + E.g. the b accesses in: >>> + >>> + for (int i = 0; i < n; ++i) >>> + b[i + 4][0] = b[i][0]; >>> + >>> + have a definite dependence distance of 4, while for: >>> + >>> + for (int i = 0; i < n; ++i) >>> + a[i + 4][0] = b[i][0]; >>> + >>> + the dependence distance depends on the gap between a and b. >>> + >>> + If the bases are different then we can only rely on the sequence >>> + rooted at a structure access, since arrays are allowed to overlap >>> + arbitrarily and change shape arbitrarily. E.g. we treat this as >>> + valid code: >>> + >>> + int a[256]; >>> + ... >>> + ((int (*)[4][3]) &a[1])[i][0] += ((int (*)[4][3]) &a[2])[i][0]; >>> + >>> + where two lvalues with the same int[4][3] type overlap, and where >>> + both lvalues are distinct from the object's declared type. */ >>> + if (same_base_p) >>> { >>> - DDR_ARE_DEPENDENT (res) = chrec_dont_know; >>> - return res; >>> + if (DR_UNCONSTRAINED_BASE (a)) >>> + full_seq.length += 1; >>> } >>> + else >>> + full_seq = struct_seq; >>> >>> - /* If the base of the object is not invariant in the loop nest, we cannot >>> - analyze it. TODO -- in fact, it would suffice to record that there >>> may >>> - be arbitrary dependences in the loops where the base object varies. >>> */ >>> - if ((loop_nest.exists () >>> - && !object_address_invariant_in_loop_p (loop_nest[0], DR_BASE_OBJECT >> (a))) >>> - || DR_NUM_DIMENSIONS (a) == 0) >>> + /* Punt if we didn't find a suitable sequence. */ >>> + if (full_seq.length == 0) >>> { >>> DDR_ARE_DEPENDENT (res) = chrec_dont_know; >>> return res; >>> } >>> >>> - /* If the number of dimensions of the access to not agree we can have >>> - a pointer access to a component of the array element type and an >>> - array access while the base-objects are still the same. Punt. */ >>> - if (DR_NUM_DIMENSIONS (a) != DR_NUM_DIMENSIONS (b)) >>> + if (!same_base_p) >>> { >>> - DDR_ARE_DEPENDENT (res) = chrec_dont_know; >>> - return res; >>> + /* Partial overlap is possible for different bases when strict >>> aliasing >>> + is not in effect. It's also possible if either base involves a >>> union >>> + access; e.g. for: >>> + >>> + struct s1 { int a[2]; }; >>> + struct s2 { struct s1 b; int c; }; >>> + struct s3 { int d; struct s1 e; }; >>> + union u { struct s2 f; struct s3 g; } *p, *q; >>> + >>> + the s1 at "p->f.b" (base "p->f") partially overlaps the s1 at >>> + "p->g.e" (base "p->g") and might partially overlap the s1 at >>> + "q->g.e" (base "q->g"). */ >>> + if (!flag_strict_aliasing >>> + || ref_contains_union_access_p (full_seq.object_a) >>> + || ref_contains_union_access_p (full_seq.object_b)) >>> + { >>> + DDR_ARE_DEPENDENT (res) = chrec_dont_know; >>> + return res; >>> + } >>> + >>> + DDR_COULD_BE_INDEPENDENT_P (res) = true; >>> } >>> >>> DDR_AFFINE_P (res) = true; >>> DDR_ARE_DEPENDENT (res) = NULL_TREE; >>> - DDR_SUBSCRIPTS (res).create (DR_NUM_DIMENSIONS (a)); >>> + DDR_SUBSCRIPTS (res).create (full_seq.length); >>> DDR_LOOP_NEST (res) = loop_nest; >>> DDR_INNER_LOOP (res) = 0; >>> DDR_SELF_REFERENCE (res) = false; >>> >>> - for (i = 0; i < DR_NUM_DIMENSIONS (a); i++) >>> + for (i = 0; i < full_seq.length; ++i) >>> { >>> struct subscript *subscript; >>> >>> subscript = XNEW (struct subscript); >>> + SUB_ACCESS_FN (subscript, 0) = DR_ACCESS_FN (a, full_seq.start_a + >>> i); >>> + SUB_ACCESS_FN (subscript, 1) = DR_ACCESS_FN (b, full_seq.start_b + >>> i); >>> SUB_CONFLICTS_IN_A (subscript) = conflict_fn_not_known (); >>> SUB_CONFLICTS_IN_B (subscript) = conflict_fn_not_known (); >>> SUB_LAST_CONFLICT (subscript) = chrec_dont_know; >>> @@ -3839,14 +4103,15 @@ add_outer_distances (struct data_depende >>> } >>> >>> /* Return false when fail to represent the data dependence as a >>> - distance vector. INIT_B is set to true when a component has been >>> + distance vector. A_INDEX is the index of the first reference >>> + (0 for DDR_A, 1 for DDR_B) and B_INDEX is the index of the >>> + second reference. INIT_B is set to true when a component has been >>> added to the distance vector DIST_V. INDEX_CARRY is then set to >>> the index in DIST_V that carries the dependence. */ >>> >>> static bool >>> build_classic_dist_vector_1 (struct data_dependence_relation *ddr, >>> - struct data_reference *ddr_a, >>> - struct data_reference *ddr_b, >>> + unsigned int a_index, unsigned int b_index, >>> lambda_vector dist_v, bool *init_b, >>> int *index_carry) >>> { >>> @@ -3864,8 +4129,8 @@ build_classic_dist_vector_1 (struct data >>> return false; >>> } >>> >>> - access_fn_a = DR_ACCESS_FN (ddr_a, i); >>> - access_fn_b = DR_ACCESS_FN (ddr_b, i); >>> + access_fn_a = SUB_ACCESS_FN (subscript, a_index); >>> + access_fn_b = SUB_ACCESS_FN (subscript, b_index); >>> >>> if (TREE_CODE (access_fn_a) == POLYNOMIAL_CHREC >>> && TREE_CODE (access_fn_b) == POLYNOMIAL_CHREC) >>> @@ -3925,10 +4190,11 @@ build_classic_dist_vector_1 (struct data >>> constant_access_functions (const struct data_dependence_relation *ddr) >>> { >>> unsigned i; >>> + subscript *sub; >>> >>> - for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++) >>> - if (!evolution_function_is_constant_p (DR_ACCESS_FN (DDR_A (ddr), i)) >>> - || !evolution_function_is_constant_p (DR_ACCESS_FN (DDR_B (ddr), >>> i))) >>> + FOR_EACH_VEC_ELT (DDR_SUBSCRIPTS (ddr), i, sub) >>> + if (!evolution_function_is_constant_p (SUB_ACCESS_FN (sub, 0)) >>> + || !evolution_function_is_constant_p (SUB_ACCESS_FN (sub, 1))) >>> return false; >>> >>> return true; >>> @@ -3991,10 +4257,11 @@ add_other_self_distances (struct data_de >>> lambda_vector dist_v; >>> unsigned i; >>> int index_carry = DDR_NB_LOOPS (ddr); >>> + subscript *sub; >>> >>> - for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++) >>> + FOR_EACH_VEC_ELT (DDR_SUBSCRIPTS (ddr), i, sub) >>> { >>> - tree access_fun = DR_ACCESS_FN (DDR_A (ddr), i); >>> + tree access_fun = SUB_ACCESS_FN (sub, 0); >>> >>> if (TREE_CODE (access_fun) == POLYNOMIAL_CHREC) >>> { >>> @@ -4006,7 +4273,7 @@ add_other_self_distances (struct data_de >>> return; >>> } >>> >>> - access_fun = DR_ACCESS_FN (DDR_A (ddr), 0); >>> + access_fun = SUB_ACCESS_FN (DDR_SUBSCRIPT (ddr, 0), 0); >>> >>> if (TREE_CODE (CHREC_LEFT (access_fun)) == POLYNOMIAL_CHREC) >>> add_multivariate_self_dist (ddr, access_fun); >>> @@ -4077,6 +4344,23 @@ add_distance_for_zero_overlaps (struct d >>> } >>> } >>> >>> +/* Return true when the DDR contains two data references that have the >>> + same access functions. */ >>> + >>> +static inline bool >>> +same_access_functions (const struct data_dependence_relation *ddr) >>> +{ >>> + unsigned i; >>> + subscript *sub; >>> + >>> + FOR_EACH_VEC_ELT (DDR_SUBSCRIPTS (ddr), i, sub) >>> + if (!eq_evolutions_p (SUB_ACCESS_FN (sub, 0), >>> + SUB_ACCESS_FN (sub, 1))) >>> + return false; >>> + >>> + return true; >>> +} >>> + >>> /* Compute the classic per loop distance vector. DDR is the data >>> dependence relation to build a vector from. Return false when fail >>> to represent the data dependence as a distance vector. */ >>> @@ -4108,8 +4392,7 @@ build_classic_dist_vector (struct data_d >>> } >>> >>> dist_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); >>> - if (!build_classic_dist_vector_1 (ddr, DDR_A (ddr), DDR_B (ddr), >>> - dist_v, &init_b, &index_carry)) >>> + if (!build_classic_dist_vector_1 (ddr, 0, 1, dist_v, &init_b, >> &index_carry)) >>> return false; >>> >>> /* Save the distance vector if we initialized one. */ >>> @@ -4142,12 +4425,11 @@ build_classic_dist_vector (struct data_d >>> if (!lambda_vector_lexico_pos (dist_v, DDR_NB_LOOPS (ddr))) >>> { >>> lambda_vector save_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); >>> - if (!subscript_dependence_tester_1 (ddr, DDR_B (ddr), DDR_A (ddr), >>> - loop_nest)) >>> + if (!subscript_dependence_tester_1 (ddr, 1, 0, loop_nest)) >>> return false; >>> compute_subscript_distance (ddr); >>> - if (!build_classic_dist_vector_1 (ddr, DDR_B (ddr), DDR_A (ddr), >>> - save_v, &init_b, &index_carry)) >>> + if (!build_classic_dist_vector_1 (ddr, 1, 0, save_v, &init_b, >>> + &index_carry)) >>> return false; >>> save_dist_v (ddr, save_v); >>> DDR_REVERSED_P (ddr) = true; >>> @@ -4183,12 +4465,10 @@ build_classic_dist_vector (struct data_d >>> { >>> lambda_vector opposite_v = lambda_vector_new (DDR_NB_LOOPS (ddr)); >>> >>> - if (!subscript_dependence_tester_1 (ddr, DDR_B (ddr), >>> - DDR_A (ddr), loop_nest)) >>> + if (!subscript_dependence_tester_1 (ddr, 1, 0, loop_nest)) >>> return false; >>> compute_subscript_distance (ddr); >>> - if (!build_classic_dist_vector_1 (ddr, DDR_B (ddr), DDR_A >>> (ddr), >>> - opposite_v, &init_b, >>> + if (!build_classic_dist_vector_1 (ddr, 1, 0, opposite_v, &init_b, >>> &index_carry)) >>> return false; >>> >>> @@ -4267,13 +4547,13 @@ build_classic_dir_vector (struct data_de >>> } >>> } >>> >>> -/* Helper function. Returns true when there is a dependence between >>> - data references DRA and DRB. */ >>> +/* Helper function. Returns true when there is a dependence between the >>> + data references. A_INDEX is the index of the first reference (0 for >>> + DDR_A, 1 for DDR_B) and B_INDEX is the index of the second reference. >>> */ >>> >>> static bool >>> subscript_dependence_tester_1 (struct data_dependence_relation *ddr, >>> - struct data_reference *dra, >>> - struct data_reference *drb, >>> + unsigned int a_index, unsigned int b_index, >>> struct loop *loop_nest) >>> { >>> unsigned int i; >>> @@ -4285,8 +4565,8 @@ subscript_dependence_tester_1 (struct da >>> { >>> conflict_function *overlaps_a, *overlaps_b; >>> >>> - analyze_overlapping_iterations (DR_ACCESS_FN (dra, i), >>> - DR_ACCESS_FN (drb, i), >>> + analyze_overlapping_iterations (SUB_ACCESS_FN (subscript, a_index), >>> + SUB_ACCESS_FN (subscript, b_index), >>> &overlaps_a, &overlaps_b, >>> &last_conflicts, loop_nest); >>> >>> @@ -4335,7 +4615,7 @@ subscript_dependence_tester_1 (struct da >>> subscript_dependence_tester (struct data_dependence_relation *ddr, >>> struct loop *loop_nest) >>> { >>> - if (subscript_dependence_tester_1 (ddr, DDR_A (ddr), DDR_B (ddr), >> loop_nest)) >>> + if (subscript_dependence_tester_1 (ddr, 0, 1, loop_nest)) >>> dependence_stats.num_dependence_dependent++; >>> >>> compute_subscript_distance (ddr); >>> Index: gcc/tree-ssa-loop-prefetch.c >>> =================================================================== >>> --- gcc/tree-ssa-loop-prefetch.c 2017-07-27 13:10:29.620045506 +0100 >>> +++ gcc/tree-ssa-loop-prefetch.c 2017-07-27 13:10:33.023912613 +0100 >>> @@ -1668,6 +1668,7 @@ determine_loop_nest_reuse (struct loop * >>> refb = (struct mem_ref *) DDR_B (dep)->aux; >>> >>> if (DDR_ARE_DEPENDENT (dep) == chrec_dont_know >>> + || DDR_COULD_BE_INDEPENDENT_P (dep) >>> || DDR_NUM_DIST_VECTS (dep) == 0) >>> { >>> /* If the dependence cannot be analyzed, assume that there might >>> be >>> Index: gcc/tree-vectorizer.h >>> =================================================================== >>> --- gcc/tree-vectorizer.h 2017-07-27 13:10:29.620045506 +0100 >>> +++ gcc/tree-vectorizer.h 2017-07-27 13:10:33.024912868 +0100 >>> @@ -358,7 +358,7 @@ #define LOOP_VINFO_ORIG_LOOP_INFO(L) >>> #define LOOP_REQUIRES_VERSIONING_FOR_ALIGNMENT(L) \ >>> ((L)->may_misalign_stmts.length () > 0) >>> #define LOOP_REQUIRES_VERSIONING_FOR_ALIAS(L) \ >>> - ((L)->may_alias_ddrs.length () > 0) >>> + ((L)->comp_alias_ddrs.length () > 0) >>> #define LOOP_REQUIRES_VERSIONING_FOR_NITERS(L) \ >>> (LOOP_VINFO_NITERS_ASSUMPTIONS (L)) >>> #define LOOP_REQUIRES_VERSIONING(L) \ >>> Index: gcc/tree-vect-data-refs.c >>> =================================================================== >>> --- gcc/tree-vect-data-refs.c 2017-07-27 13:10:29.620045506 +0100 >>> +++ gcc/tree-vect-data-refs.c 2017-07-27 13:10:33.024912868 +0100 >>> @@ -160,6 +160,60 @@ vect_mark_for_runtime_alias_test (ddr_p >>> } >>> >>> >>> +/* A subroutine of vect_analyze_data_ref_dependence. Handle >>> + DDR_COULD_BE_INDEPENDENT_P ddr DDR that has a known set of dependence >>> + distances. These distances are conservatively correct but they don't >>> + reflect a guaranteed dependence. >>> + >>> + Return true if this function does all the work necessary to avoid >>> + an alias or false if the caller should use the dependence distances >>> + to limit the vectorization factor in the usual way. LOOP_DEPTH is >>> + the depth of the loop described by LOOP_VINFO and the other arguments >>> + are as for vect_analyze_data_ref_dependence. */ >>> + >>> +static bool >>> +vect_analyze_possibly_independent_ddr (data_dependence_relation *ddr, >>> + loop_vec_info loop_vinfo, >>> + int loop_depth, int *max_vf) >>> +{ >>> + struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo); >>> + lambda_vector dist_v; >>> + unsigned int i; >>> + FOR_EACH_VEC_ELT (DDR_DIST_VECTS (ddr), i, dist_v) >>> + { >>> + int dist = dist_v[loop_depth]; >>> + if (dist != 0 && !(dist > 0 && DDR_REVERSED_P (ddr))) >>> + { >>> + /* If the user asserted safelen >= DIST consecutive iterations >>> + can be executed concurrently, assume independence. >>> + >>> + ??? An alternative would be to add the alias check even >>> + in this case, and vectorize the fallback loop with the >>> + maximum VF set to safelen. However, if the user has >>> + explicitly given a length, it's less likely that that >>> + would be a win. */ >>> + if (loop->safelen >= 2 && abs_hwi (dist) <= loop->safelen) >>> + { >>> + if (loop->safelen < *max_vf) >>> + *max_vf = loop->safelen; >>> + LOOP_VINFO_NO_DATA_DEPENDENCIES (loop_vinfo) = false; >>> + continue; >>> + } >>> + >>> + /* For dependence distances of 2 or more, we have the option >>> + of limiting VF or checking for an alias at runtime. >>> + Prefer to check at runtime if we can, to avoid limiting >>> + the VF unnecessarily when the bases are in fact independent. >>> + >>> + Note that the alias checks will be removed if the VF ends up >>> + being small enough. */ >>> + return vect_mark_for_runtime_alias_test (ddr, loop_vinfo); >>> + } >>> + } >>> + return true; >>> +} >>> + >>> + >>> /* Function vect_analyze_data_ref_dependence. >>> >>> Return TRUE if there (might) exist a dependence between a >>> memory-reference >>> @@ -305,6 +359,12 @@ vect_analyze_data_ref_dependence (struct >>> } >>> >>> loop_depth = index_in_loop_nest (loop->num, DDR_LOOP_NEST (ddr)); >>> + >>> + if (DDR_COULD_BE_INDEPENDENT_P (ddr) >>> + && vect_analyze_possibly_independent_ddr (ddr, loop_vinfo, >>> + loop_depth, max_vf)) >>> + return false; >>> + >>> FOR_EACH_VEC_ELT (DDR_DIST_VECTS (ddr), i, dist_v) >>> { >>> int dist = dist_v[loop_depth]; >>> @@ -2878,6 +2938,44 @@ vect_no_alias_p (struct data_reference * >>> return false; >>> } >>> >>> +/* Return true if the minimum nonzero dependence distance for loop >>> LOOP_DEPTH >>> + in DDR is >= VF. */ >>> + >>> +static bool >>> +dependence_distance_ge_vf (data_dependence_relation *ddr, >>> + unsigned int loop_depth, unsigned HOST_WIDE_INT >>> vf) >>> +{ >>> + if (DDR_ARE_DEPENDENT (ddr) != NULL_TREE >>> + || DDR_NUM_DIST_VECTS (ddr) == 0) >>> + return false; >>> + >>> + /* If the dependence is exact, we should have limited the VF instead. */ >>> + gcc_checking_assert (DDR_COULD_BE_INDEPENDENT_P (ddr)); >>> + >>> + unsigned int i; >>> + lambda_vector dist_v; >>> + FOR_EACH_VEC_ELT (DDR_DIST_VECTS (ddr), i, dist_v) >>> + { >>> + HOST_WIDE_INT dist = dist_v[loop_depth]; >>> + if (dist != 0 >>> + && !(dist > 0 && DDR_REVERSED_P (ddr)) >>> + && (unsigned HOST_WIDE_INT) abs_hwi (dist) < vf) >>> + return false; >>> + } >>> + >>> + if (dump_enabled_p ()) >>> + { >>> + dump_printf_loc (MSG_NOTE, vect_location, >>> + "dependence distance between "); >>> + dump_generic_expr (MSG_NOTE, TDF_SLIM, DR_REF (DDR_A (ddr))); >>> + dump_printf (MSG_NOTE, " and "); >>> + dump_generic_expr (MSG_NOTE, TDF_SLIM, DR_REF (DDR_B (ddr))); >>> + dump_printf (MSG_NOTE, " is >= VF\n"); >>> + } >>> + >>> + return true; >>> +} >>> + >>> /* Function vect_prune_runtime_alias_test_list. >>> >>> Prune a list of ddrs to be tested at run-time by versioning for alias. >>> @@ -2908,6 +3006,10 @@ vect_prune_runtime_alias_test_list (loop >>> >>> comp_alias_ddrs.create (may_alias_ddrs.length ()); >>> >>> + unsigned int loop_depth >>> + = index_in_loop_nest (LOOP_VINFO_LOOP (loop_vinfo)->num, >>> + LOOP_VINFO_LOOP_NEST (loop_vinfo)); >>> + >>> /* First, we collect all data ref pairs for aliasing checks. */ >>> FOR_EACH_VEC_ELT (may_alias_ddrs, i, ddr) >>> { >>> @@ -2917,6 +3019,11 @@ vect_prune_runtime_alias_test_list (loop >>> tree segment_length_a, segment_length_b; >>> gimple *stmt_a, *stmt_b; >>> >>> + /* Ignore the alias if the VF we chose ended up being no greater >>> + than the dependence distance. */ >>> + if (dependence_distance_ge_vf (ddr, loop_depth, vect_factor)) >>> + continue; >>> + >>> dr_a = DDR_A (ddr); >>> stmt_a = DR_STMT (DDR_A (ddr)); >>> dr_group_first_a = GROUP_FIRST_ELEMENT (vinfo_for_stmt (stmt_a)); >>> @@ -2993,10 +3100,6 @@ vect_prune_runtime_alias_test_list (loop >>> return false; >>> } >>> >>> - /* All alias checks have been resolved at compilation time. */ >>> - if (!comp_alias_ddrs.length ()) >>> - LOOP_VINFO_MAY_ALIAS_DDRS (loop_vinfo).truncate (0); >>> - >>> return true; >>> } >>> >>> Index: gcc/testsuite/gcc.dg/vect/vect-alias-check-3.c >>> =================================================================== >>> --- /dev/null 2017-07-27 10:25:31.671280760 +0100 >>> +++ gcc/testsuite/gcc.dg/vect/vect-alias-check-3.c 2017-07-27 >> 13:10:33.022912357 +0100 >>> @@ -0,0 +1,120 @@ >>> +/* { dg-do compile } */ >>> +/* { dg-require-effective-target vect_int } */ >>> +/* { dg-additional-options "--param >> vect-max-version-for-alias-checks=0 -fopenmp-simd" } */ >>> + >>> +/* Intended to be larger than any VF. */ >>> +#define GAP 128 >>> +#define N (GAP * 3) >>> + >>> +struct s { int x[N + 1]; }; >>> +struct t { struct s x[N + 1]; }; >>> +struct u { int x[N + 1]; int y; }; >>> +struct v { struct s s; }; >>> + >>> +void >>> +f1 (struct s *a, struct s *b) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a->x[i] += b->x[i]; >>> +} >>> + >>> +void >>> +f2 (struct s *a, struct s *b) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a[1].x[i] += b[2].x[i]; >>> +} >>> + >>> +void >>> +f3 (struct s *a, struct s *b) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a[1].x[i] += b[i].x[i]; >>> +} >>> + >>> +void >>> +f4 (struct s *a, struct s *b) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a[i].x[i] += b[i].x[i]; >>> +} >>> + >>> +void >>> +f5 (struct s *a, struct s *b) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a->x[i] += b->x[i + 1]; >>> +} >>> + >>> +void >>> +f6 (struct s *a, struct s *b) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a[1].x[i] += b[2].x[i + 1]; >>> +} >>> + >>> +void >>> +f7 (struct s *a, struct s *b) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a[1].x[i] += b[i].x[i + 1]; >>> +} >>> + >>> +void >>> +f8 (struct s *a, struct s *b) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a[i].x[i] += b[i].x[i + 1]; >>> +} >>> + >>> +void >>> +f9 (struct s *a, struct t *b) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a->x[i] += b->x[1].x[i]; >>> +} >>> + >>> +void >>> +f10 (struct s *a, struct t *b) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a->x[i] += b->x[i].x[i]; >>> +} >>> + >>> +void >>> +f11 (struct u *a, struct u *b) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a->x[i] += b->x[i] + b[i].y; >>> +} >>> + >>> +void >>> +f12 (struct s *a, struct s *b) >>> +{ >>> + for (int i = 0; i < GAP; ++i) >>> + a->x[i + GAP] += b->x[i]; >>> +} >>> + >>> +void >>> +f13 (struct s *a, struct s *b) >>> +{ >>> + for (int i = 0; i < GAP * 2; ++i) >>> + a->x[i + GAP] += b->x[i]; >>> +} >>> + >>> +void >>> +f14 (struct v *a, struct s *b) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a->s.x[i] = b->x[i]; >>> +} >>> + >>> +void >>> +f15 (struct s *a, struct s *b) >>> +{ >>> + #pragma omp simd safelen(N) >>> + for (int i = 0; i < N; ++i) >>> + a->x[i + 1] += b->x[i]; >>> +} >>> + >>> +/* { dg-final { scan-tree-dump-times "LOOP VECTORIZED" 15 "vect" } } */ >>> Index: gcc/testsuite/gcc.dg/vect/vect-alias-check-4.c >>> =================================================================== >>> --- /dev/null 2017-07-27 10:25:31.671280760 +0100 >>> +++ gcc/testsuite/gcc.dg/vect/vect-alias-check-4.c 2017-07-27 >> 13:10:33.022912357 +0100 >>> @@ -0,0 +1,35 @@ >>> +/* { dg-do compile } */ >>> +/* { dg-require-effective-target vect_int } */ >>> +/* { dg-additional-options "--param vect-max-version-for-alias-checks=0" } >>> */ >>> + >>> +#define N 16 >>> + >>> +struct s1 { int a[N]; }; >>> +struct s2 { struct s1 b; int c; }; >>> +struct s3 { int d; struct s1 e; }; >>> +union u { struct s2 f; struct s3 g; }; >>> + >>> +/* We allow a and b to overlap arbitrarily. */ >>> + >>> +void >>> +f1 (int a[][N], int b[][N]) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a[0][i] += b[0][i]; >>> +} >>> + >>> +void >>> +f2 (union u *a, union u *b) >>> +{ >>> + for (int i = 0; i < N; ++i) >>> + a->f.b.a[i] += b->g.e.a[i]; >>> +} >>> + >>> +void >>> +f3 (struct s1 *a, struct s1 *b) >>> +{ >>> + for (int i = 0; i < N - 1; ++i) >>> + a->a[i + 1] += b->a[i]; >>> +} >>> + >>> +/* { dg-final { scan-tree-dump-not "LOOP VECTORIZED" "vect" } } */ >>> Index: gcc/testsuite/gcc.dg/vect/vect-alias-check-5.c >>> =================================================================== >>> --- /dev/null 2017-07-27 10:25:31.671280760 +0100 >>> +++ gcc/testsuite/gcc.dg/vect/vect-alias-check-5.c 2017-07-27 >> 13:10:33.022912357 +0100 >>> @@ -0,0 +1,19 @@ >>> +/* { dg-do compile } */ >>> +/* { dg-require-effective-target vect_int } */ >>> + >>> +/* Intended to be larger than any VF. */ >>> +#define GAP 128 >>> +#define N (GAP * 3) >>> + >>> +struct s { int x[N]; }; >>> + >>> +void >>> +f1 (struct s *a, struct s *b) >>> +{ >>> + for (int i = 0; i < GAP * 2; ++i) >>> + a->x[i + GAP] += b->x[i]; >>> +} >>> + >>> +/* { dg-final { scan-tree-dump-times "consider run-time aliasing" 1 >> "vect" } } */ >>> +/* { dg-final { scan-tree-dump-times "improved number of alias checks >> from 1 to 0" 1 "vect" } } */ >>> +/* { dg-final { scan-tree-dump-times "LOOP VECTORIZED" 1 "vect" } } */