/* Data references and dependences detectors.
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Copyright (C) 2003-2017 Free Software Foundation, Inc.
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Contributed by Sebastian Pop <pop@cri.ensmp.fr>
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 3, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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#ifndef GCC_TREE_DATA_REF_H
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#define GCC_TREE_DATA_REF_H
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#include "graphds.h"
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#include "tree-chrec.h"
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/*
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innermost_loop_behavior describes the evolution of the address of the memory
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reference in the innermost enclosing loop. The address is expressed as
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BASE + STEP * # of iteration, and base is further decomposed as the base
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pointer (BASE_ADDRESS), loop invariant offset (OFFSET) and
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constant offset (INIT). Examples, in loop nest
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for (i = 0; i < 100; i++)
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for (j = 3; j < 100; j++)
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Example 1 Example 2
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data-ref a[j].b[i][j] *(p + x + 16B + 4B * j)
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innermost_loop_behavior
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base_address &a p
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offset i * D_i x
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init 3 * D_j + offsetof (b) 28
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step D_j 4
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*/
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struct innermost_loop_behavior
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{
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tree base_address;
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tree offset;
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tree init;
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tree step;
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/* Alignment information. ALIGNED_TO is set to the largest power of two
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that divides OFFSET. */
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tree aligned_to;
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};
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/* Describes the evolutions of indices of the memory reference. The indices
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are indices of the ARRAY_REFs, indexes in artificial dimensions
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added for member selection of records and the operands of MEM_REFs.
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BASE_OBJECT is the part of the reference that is loop-invariant
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(note that this reference does not have to cover the whole object
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being accessed, in which case UNCONSTRAINED_BASE is set; hence it is
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not recommended to use BASE_OBJECT in any code generation).
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For the examples above,
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base_object: a *(p + x + 4B * j_0)
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indices: {j_0, +, 1}_2 {16, +, 4}_2
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4
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{i_0, +, 1}_1
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{j_0, +, 1}_2
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*/
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struct indices
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{
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/* The object. */
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tree base_object;
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/* A list of chrecs. Access functions of the indices. */
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vec<tree> access_fns;
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/* Whether BASE_OBJECT is an access representing the whole object
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or whether the access could not be constrained. */
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bool unconstrained_base;
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};
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struct dr_alias
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{
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/* The alias information that should be used for new pointers to this
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location. */
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struct ptr_info_def *ptr_info;
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};
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/* An integer vector. A vector formally consists of an element of a vector
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space. A vector space is a set that is closed under vector addition
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and scalar multiplication. In this vector space, an element is a list of
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integers. */
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typedef int *lambda_vector;
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/* An integer matrix. A matrix consists of m vectors of length n (IE
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all vectors are the same length). */
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typedef lambda_vector *lambda_matrix;
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struct data_reference
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{
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/* A pointer to the statement that contains this DR. */
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gimple *stmt;
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/* A pointer to the memory reference. */
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tree ref;
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/* Auxiliary info specific to a pass. */
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void *aux;
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/* True when the data reference is in RHS of a stmt. */
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bool is_read;
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/* Behavior of the memory reference in the innermost loop. */
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struct innermost_loop_behavior innermost;
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/* Subscripts of this data reference. */
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struct indices indices;
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/* Alias information for the data reference. */
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struct dr_alias alias;
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};
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#define DR_STMT(DR) (DR)->stmt
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#define DR_REF(DR) (DR)->ref
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#define DR_BASE_OBJECT(DR) (DR)->indices.base_object
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#define DR_UNCONSTRAINED_BASE(DR) (DR)->indices.unconstrained_base
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#define DR_ACCESS_FNS(DR) (DR)->indices.access_fns
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#define DR_ACCESS_FN(DR, I) DR_ACCESS_FNS (DR)[I]
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#define DR_NUM_DIMENSIONS(DR) DR_ACCESS_FNS (DR).length ()
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#define DR_IS_READ(DR) (DR)->is_read
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#define DR_IS_WRITE(DR) (!DR_IS_READ (DR))
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#define DR_BASE_ADDRESS(DR) (DR)->innermost.base_address
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#define DR_OFFSET(DR) (DR)->innermost.offset
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#define DR_INIT(DR) (DR)->innermost.init
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#define DR_STEP(DR) (DR)->innermost.step
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#define DR_PTR_INFO(DR) (DR)->alias.ptr_info
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#define DR_ALIGNED_TO(DR) (DR)->innermost.aligned_to
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#define DR_INNERMOST(DR) (DR)->innermost
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typedef struct data_reference *data_reference_p;
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enum data_dependence_direction {
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dir_positive,
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dir_negative,
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dir_equal,
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dir_positive_or_negative,
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dir_positive_or_equal,
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dir_negative_or_equal,
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dir_star,
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dir_independent
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};
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/* The description of the grid of iterations that overlap. At most
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two loops are considered at the same time just now, hence at most
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two functions are needed. For each of the functions, we store
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the vector of coefficients, f[0] + x * f[1] + y * f[2] + ...,
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where x, y, ... are variables. */
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#define MAX_DIM 2
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/* Special values of N. */
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#define NO_DEPENDENCE 0
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#define NOT_KNOWN (MAX_DIM + 1)
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#define CF_NONTRIVIAL_P(CF) ((CF)->n != NO_DEPENDENCE && (CF)->n != NOT_KNOWN)
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#define CF_NOT_KNOWN_P(CF) ((CF)->n == NOT_KNOWN)
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#define CF_NO_DEPENDENCE_P(CF) ((CF)->n == NO_DEPENDENCE)
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typedef vec<tree> affine_fn;
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struct conflict_function
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{
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unsigned n;
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affine_fn fns[MAX_DIM];
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};
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/* What is a subscript? Given two array accesses a subscript is the
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tuple composed of the access functions for a given dimension.
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Example: Given A[f1][f2][f3] and B[g1][g2][g3], there are three
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subscripts: (f1, g1), (f2, g2), (f3, g3). These three subscripts
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are stored in the data_dependence_relation structure under the form
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of an array of subscripts. */
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struct subscript
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{
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/* A description of the iterations for which the elements are
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accessed twice. */
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conflict_function *conflicting_iterations_in_a;
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conflict_function *conflicting_iterations_in_b;
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/* This field stores the information about the iteration domain
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validity of the dependence relation. */
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tree last_conflict;
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/* Distance from the iteration that access a conflicting element in
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A to the iteration that access this same conflicting element in
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B. The distance is a tree scalar expression, i.e. a constant or a
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symbolic expression, but certainly not a chrec function. */
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tree distance;
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};
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typedef struct subscript *subscript_p;
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#define SUB_CONFLICTS_IN_A(SUB) SUB->conflicting_iterations_in_a
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#define SUB_CONFLICTS_IN_B(SUB) SUB->conflicting_iterations_in_b
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#define SUB_LAST_CONFLICT(SUB) SUB->last_conflict
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#define SUB_DISTANCE(SUB) SUB->distance
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/* A data_dependence_relation represents a relation between two
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data_references A and B. */
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struct data_dependence_relation
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{
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struct data_reference *a;
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struct data_reference *b;
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/* A "yes/no/maybe" field for the dependence relation:
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- when "ARE_DEPENDENT == NULL_TREE", there exist a dependence
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relation between A and B, and the description of this relation
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is given in the SUBSCRIPTS array,
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- when "ARE_DEPENDENT == chrec_known", there is no dependence and
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SUBSCRIPTS is empty,
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- when "ARE_DEPENDENT == chrec_dont_know", there may be a dependence,
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but the analyzer cannot be more specific. */
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tree are_dependent;
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/* For each subscript in the dependence test, there is an element in
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this array. This is the attribute that labels the edge A->B of
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the data_dependence_relation. */
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vec<subscript_p> subscripts;
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/* The analyzed loop nest. */
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vec<loop_p> loop_nest;
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/* The classic direction vector. */
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vec<lambda_vector> dir_vects;
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/* The classic distance vector. */
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vec<lambda_vector> dist_vects;
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/* An index in loop_nest for the innermost loop that varies for
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this data dependence relation. */
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unsigned inner_loop;
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/* Is the dependence reversed with respect to the lexicographic order? */
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bool reversed_p;
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/* When the dependence relation is affine, it can be represented by
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a distance vector. */
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bool affine_p;
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/* Set to true when the dependence relation is on the same data
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access. */
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bool self_reference_p;
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};
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typedef struct data_dependence_relation *ddr_p;
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#define DDR_A(DDR) DDR->a
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#define DDR_B(DDR) DDR->b
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#define DDR_AFFINE_P(DDR) DDR->affine_p
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#define DDR_ARE_DEPENDENT(DDR) DDR->are_dependent
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#define DDR_SUBSCRIPTS(DDR) DDR->subscripts
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#define DDR_SUBSCRIPT(DDR, I) DDR_SUBSCRIPTS (DDR)[I]
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#define DDR_NUM_SUBSCRIPTS(DDR) DDR_SUBSCRIPTS (DDR).length ()
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#define DDR_LOOP_NEST(DDR) DDR->loop_nest
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/* The size of the direction/distance vectors: the number of loops in
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the loop nest. */
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#define DDR_NB_LOOPS(DDR) (DDR_LOOP_NEST (DDR).length ())
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#define DDR_INNER_LOOP(DDR) DDR->inner_loop
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#define DDR_SELF_REFERENCE(DDR) DDR->self_reference_p
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#define DDR_DIST_VECTS(DDR) ((DDR)->dist_vects)
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#define DDR_DIR_VECTS(DDR) ((DDR)->dir_vects)
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#define DDR_NUM_DIST_VECTS(DDR) \
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(DDR_DIST_VECTS (DDR).length ())
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#define DDR_NUM_DIR_VECTS(DDR) \
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(DDR_DIR_VECTS (DDR).length ())
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#define DDR_DIR_VECT(DDR, I) \
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DDR_DIR_VECTS (DDR)[I]
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#define DDR_DIST_VECT(DDR, I) \
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DDR_DIST_VECTS (DDR)[I]
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#define DDR_REVERSED_P(DDR) DDR->reversed_p
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bool dr_analyze_innermost (struct data_reference *, struct loop *);
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extern bool compute_data_dependences_for_loop (struct loop *, bool,
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vec<loop_p> *,
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vec<data_reference_p> *,
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vec<ddr_p> *);
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extern void debug_ddrs (vec<ddr_p> );
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extern void dump_data_reference (FILE *, struct data_reference *);
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extern void debug (data_reference &ref);
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extern void debug (data_reference *ptr);
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extern void debug_data_reference (struct data_reference *);
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extern void debug_data_references (vec<data_reference_p> );
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extern void debug (vec<data_reference_p> &ref);
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extern void debug (vec<data_reference_p> *ptr);
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extern void debug_data_dependence_relation (struct data_dependence_relation *);
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extern void dump_data_dependence_relations (FILE *, vec<ddr_p> );
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extern void debug (vec<ddr_p> &ref);
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extern void debug (vec<ddr_p> *ptr);
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extern void debug_data_dependence_relations (vec<ddr_p> );
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extern void free_dependence_relation (struct data_dependence_relation *);
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extern void free_dependence_relations (vec<ddr_p> );
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extern void free_data_ref (data_reference_p);
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extern void free_data_refs (vec<data_reference_p> );
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extern bool find_data_references_in_stmt (struct loop *, gimple *,
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vec<data_reference_p> *);
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extern bool graphite_find_data_references_in_stmt (loop_p, loop_p, gimple *,
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vec<data_reference_p> *);
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tree find_data_references_in_loop (struct loop *, vec<data_reference_p> *);
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bool loop_nest_has_data_refs (loop_p loop);
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struct data_reference *create_data_ref (loop_p, loop_p, tree, gimple *, bool);
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extern bool find_loop_nest (struct loop *, vec<loop_p> *);
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extern struct data_dependence_relation *initialize_data_dependence_relation
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(struct data_reference *, struct data_reference *, vec<loop_p>);
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extern void compute_affine_dependence (struct data_dependence_relation *,
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loop_p);
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extern void compute_self_dependence (struct data_dependence_relation *);
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extern bool compute_all_dependences (vec<data_reference_p> ,
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vec<ddr_p> *,
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vec<loop_p>, bool);
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extern tree find_data_references_in_bb (struct loop *, basic_block,
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vec<data_reference_p> *);
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extern bool dr_may_alias_p (const struct data_reference *,
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const struct data_reference *, bool);
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extern bool dr_equal_offsets_p (struct data_reference *,
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struct data_reference *);
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/* Return true when the base objects of data references A and B are
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the same memory object. */
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static inline bool
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same_data_refs_base_objects (data_reference_p a, data_reference_p b)
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{
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return DR_NUM_DIMENSIONS (a) == DR_NUM_DIMENSIONS (b)
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&& operand_equal_p (DR_BASE_OBJECT (a), DR_BASE_OBJECT (b), 0);
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}
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/* Return true when the data references A and B are accessing the same
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memory object with the same access functions. */
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static inline bool
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same_data_refs (data_reference_p a, data_reference_p b)
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{
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unsigned int i;
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/* The references are exactly the same. */
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if (operand_equal_p (DR_REF (a), DR_REF (b), 0))
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return true;
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if (!same_data_refs_base_objects (a, b))
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return false;
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for (i = 0; i < DR_NUM_DIMENSIONS (a); i++)
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if (!eq_evolutions_p (DR_ACCESS_FN (a, i), DR_ACCESS_FN (b, i)))
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return false;
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return true;
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}
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/* Return true when the DDR contains two data references that have the
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same access functions. */
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static inline bool
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same_access_functions (const struct data_dependence_relation *ddr)
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{
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unsigned i;
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for (i = 0; i < DDR_NUM_SUBSCRIPTS (ddr); i++)
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if (!eq_evolutions_p (DR_ACCESS_FN (DDR_A (ddr), i),
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DR_ACCESS_FN (DDR_B (ddr), i)))
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return false;
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return true;
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}
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/* Returns true when all the dependences are computable. */
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inline bool
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known_dependences_p (vec<ddr_p> dependence_relations)
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{
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ddr_p ddr;
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unsigned int i;
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FOR_EACH_VEC_ELT (dependence_relations, i, ddr)
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if (DDR_ARE_DEPENDENT (ddr) == chrec_dont_know)
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return false;
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return true;
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}
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/* Returns the dependence level for a vector DIST of size LENGTH.
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LEVEL = 0 means a lexicographic dependence, i.e. a dependence due
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to the sequence of statements, not carried by any loop. */
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static inline unsigned
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dependence_level (lambda_vector dist_vect, int length)
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{
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int i;
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for (i = 0; i < length; i++)
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if (dist_vect[i] != 0)
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return i + 1;
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return 0;
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}
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/* Return the dependence level for the DDR relation. */
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static inline unsigned
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ddr_dependence_level (ddr_p ddr)
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{
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unsigned vector;
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unsigned level = 0;
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if (DDR_DIST_VECTS (ddr).exists ())
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level = dependence_level (DDR_DIST_VECT (ddr, 0), DDR_NB_LOOPS (ddr));
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for (vector = 1; vector < DDR_NUM_DIST_VECTS (ddr); vector++)
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level = MIN (level, dependence_level (DDR_DIST_VECT (ddr, vector),
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DDR_NB_LOOPS (ddr)));
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return level;
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}
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/* Return the index of the variable VAR in the LOOP_NEST array. */
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static inline int
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index_in_loop_nest (int var, vec<loop_p> loop_nest)
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{
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struct loop *loopi;
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int var_index;
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for (var_index = 0; loop_nest.iterate (var_index, &loopi);
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var_index++)
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if (loopi->num == var)
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break;
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return var_index;
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}
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/* Returns true when the data reference DR the form "A[i] = ..."
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with a stride equal to its unit type size. */
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static inline bool
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adjacent_dr_p (struct data_reference *dr)
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{
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/* If this is a bitfield store bail out. */
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if (TREE_CODE (DR_REF (dr)) == COMPONENT_REF
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&& DECL_BIT_FIELD (TREE_OPERAND (DR_REF (dr), 1)))
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return false;
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if (!DR_STEP (dr)
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|| TREE_CODE (DR_STEP (dr)) != INTEGER_CST)
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return false;
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return tree_int_cst_equal (fold_unary (ABS_EXPR, TREE_TYPE (DR_STEP (dr)),
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DR_STEP (dr)),
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TYPE_SIZE_UNIT (TREE_TYPE (DR_REF (dr))));
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}
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void split_constant_offset (tree , tree *, tree *);
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/* Compute the greatest common divisor of a VECTOR of SIZE numbers. */
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static inline int
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lambda_vector_gcd (lambda_vector vector, int size)
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{
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int i;
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int gcd1 = 0;
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if (size > 0)
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{
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gcd1 = vector[0];
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for (i = 1; i < size; i++)
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gcd1 = gcd (gcd1, vector[i]);
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}
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return gcd1;
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}
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/* Allocate a new vector of given SIZE. */
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static inline lambda_vector
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lambda_vector_new (int size)
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{
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/* ??? We shouldn't abuse the GC allocator here. */
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return ggc_cleared_vec_alloc<int> (size);
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}
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/* Clear out vector VEC1 of length SIZE. */
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static inline void
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lambda_vector_clear (lambda_vector vec1, int size)
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{
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memset (vec1, 0, size * sizeof (*vec1));
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}
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/* Returns true when the vector V is lexicographically positive, in
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other words, when the first nonzero element is positive. */
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static inline bool
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lambda_vector_lexico_pos (lambda_vector v,
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unsigned n)
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{
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unsigned i;
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for (i = 0; i < n; i++)
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{
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if (v[i] == 0)
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continue;
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if (v[i] < 0)
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return false;
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if (v[i] > 0)
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return true;
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}
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return true;
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}
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/* Return true if vector VEC1 of length SIZE is the zero vector. */
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static inline bool
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lambda_vector_zerop (lambda_vector vec1, int size)
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{
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int i;
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for (i = 0; i < size; i++)
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if (vec1[i] != 0)
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return false;
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return true;
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}
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/* Allocate a matrix of M rows x N cols. */
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static inline lambda_matrix
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lambda_matrix_new (int m, int n, struct obstack *lambda_obstack)
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{
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lambda_matrix mat;
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int i;
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mat = XOBNEWVEC (lambda_obstack, lambda_vector, m);
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for (i = 0; i < m; i++)
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mat[i] = XOBNEWVEC (lambda_obstack, int, n);
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return mat;
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}
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#endif /* GCC_TREE_DATA_REF_H */
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