Data Fields
int	num_dependence_tests
int	num_dependence_dependent
int	num_dependence_independent
int	num_dependence_undetermined
int	num_subscript_tests
int	num_subscript_undetermined
int	num_same_subscript_function
int	num_ziv
int	num_ziv_independent
int	num_ziv_dependent
int	num_ziv_unimplemented
int	num_siv
int	num_siv_independent
int	num_siv_dependent
int	num_siv_unimplemented
int	num_miv
int	num_miv_independent
int	num_miv_dependent
int	num_miv_unimplemented

Detailed Description

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see http://www.gnu.org/licenses/. This pass walks a given loop structure searching for array references. The information about the array accesses is recorded in DATA_REFERENCE structures.

The basic test for determining the dependences is: given two access functions chrec1 and chrec2 to a same array, and x and y two vectors from the iteration domain, the same element of the array is accessed twice at iterations x and y if and only if: | chrec1 (x) == chrec2 (y).

The goals of this analysis are:

to determine the independence: the relation between two independent accesses is qualified with the chrec_known (this information allows a loop parallelization),

when two data references access the same data, to qualify the dependence relation with classic dependence representations:
- distance vectors
- direction vectors
- loop carried level dependence
- polyhedron dependence or with the chains of recurrences based representation,

to define a knowledge base for storing the data dependence information,

to define an interface to access this data.

Definitions:

subscript: given two array accesses a subscript is the tuple composed of the access functions for a given dimension. Example: Given A[f1][f2][f3] and B[g1][g2][g3], there are three subscripts: (f1, g1), (f2, g2), (f3, g3).

Diophantine equation: an equation whose coefficients and solutions are integer constants, for example the equation | 3*x + 2*y = 1 has an integer solution x = 1 and y = -1.

References: