/* Data references and dependences detectors.
- Copyright (C) 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
+ Copyright (C) 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
Contributed by Sebastian Pop <pop@cri.ensmp.fr>
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 2, or (at your option) any later
+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
for more details.
You should have received a copy of the GNU General Public License
-along with GCC; see the file COPYING. If not, write to the Free
-Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
-02110-1301, USA. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#ifndef GCC_TREE_DATA_REF_H
#define GCC_TREE_DATA_REF_H
+#include "graphds.h"
#include "lambda.h"
+#include "omega.h"
+#include "tree-chrec.h"
/*
- The first location accessed by data-ref in the loop is the address of data-ref's
- base (BASE_ADDRESS) plus the initial offset from the base. We divide the initial offset
- into two parts: loop invariant offset (OFFSET) and constant offset (INIT).
- STEP is the stride of data-ref in the loop in bytes.
+ innermost_loop_behavior describes the evolution of the address of the memory
+ reference in the innermost enclosing loop. The address is expressed as
+ BASE + STEP * # of iteration, and base is further decomposed as the base
+ pointer (BASE_ADDRESS), loop invariant offset (OFFSET) and
+ constant offset (INIT). Examples, in loop nest
+
+ for (i = 0; i < 100; i++)
+ for (j = 3; j < 100; j++)
Example 1 Example 2
- data-ref a[j].b[i][j] a + x + 16B (a is int*)
+ data-ref a[j].b[i][j] *(p + x + 16B + 4B * j)
- First location info:
- base_address &a a
- offset j_0*D_j + i_0*D_i x
- init C_b + C_a 16
- step D_j 4
- access_fn NULL {16, +, 1}
- Base object info:
- base_object a NULL
- access_fn <access_fns of indexes of b> NULL
+ innermost_loop_behavior
+ base_address &a p
+ offset i * D_i x
+ init 3 * D_j + offsetof (b) 28
+ step D_j 4
*/
-struct first_location_in_loop
+struct innermost_loop_behavior
{
tree base_address;
tree offset;
tree init;
tree step;
- /* Access function related to first location in the loop. */
- VEC(tree,heap) *access_fns;
+
+ /* Alignment information. ALIGNED_TO is set to the largest power of two
+ that divides OFFSET. */
+ tree aligned_to;
};
-struct base_object_info
+/* Describes the evolutions of indices of the memory reference. The indices
+ are indices of the ARRAY_REFs and the operands of INDIRECT_REFs.
+ For ARRAY_REFs, BASE_OBJECT is the reference with zeroed indices
+ (note that this reference does not have to be valid, if zero does not
+ belong to the range of the array; hence it is not recommended to use
+ BASE_OBJECT in any code generation). For INDIRECT_REFs, the address is
+ set to the loop-invariant part of the address of the object, except for
+ the constant offset. For the examples above,
+
+ base_object: a[0].b[0][0] *(p + x + 4B * j_0)
+ indices: {j_0, +, 1}_2 {16, +, 4}_2
+ {i_0, +, 1}_1
+ {j_0, +, 1}_2
+*/
+
+struct indices
{
/* The object. */
tree base_object;
- /* A list of chrecs. Access functions related to BASE_OBJECT. */
+ /* A list of chrecs. Access functions of the indices. */
VEC(tree,heap) *access_fns;
};
-enum data_ref_type {
- ARRAY_REF_TYPE,
- POINTER_REF_TYPE
+struct dr_alias
+{
+ /* The alias information that should be used for new pointers to this
+ location. SYMBOL_TAG is either a DECL or a SYMBOL_MEMORY_TAG. */
+ tree symbol_tag;
+ struct ptr_info_def *ptr_info;
+
+ /* The set of virtual operands corresponding to this memory reference,
+ serving as a description of the alias information for the memory
+ reference. This could be eliminated if we had alias oracle. */
+ bitmap vops;
};
struct data_reference
/* A pointer to the statement that contains this DR. */
tree stmt;
- /* A pointer to the ARRAY_REF node. */
+ /* A pointer to the memory reference. */
tree ref;
/* Auxiliary info specific to a pass. */
- int aux;
+ void *aux;
/* True when the data reference is in RHS of a stmt. */
bool is_read;
- /* First location accessed by the data-ref in the loop. */
- struct first_location_in_loop first_location;
+ /* Behavior of the memory reference in the innermost loop. */
+ struct innermost_loop_behavior innermost;
- /* Base object related info. */
- struct base_object_info object_info;
+ /* Decomposition to indices for alias analysis. */
+ struct indices indices;
- /* Aliasing information. This field represents the symbol that
- should be aliased by a pointer holding the address of this data
- reference. If the original data reference was a pointer
- dereference, then this field contains the memory tag that should
- be used by the new vector-pointer. */
- tree memtag;
- struct ptr_info_def *ptr_info;
- subvar_t subvars;
-
- /* Alignment information.
- MISALIGNMENT is the offset of the data-reference from its base in bytes.
- ALIGNED_TO is the maximum data-ref's alignment.
-
- Example 1,
- for i
- for (j = 3; j < N; j++)
- a[j].b[i][j] = 0;
-
- For a[j].b[i][j], the offset from base (calculated in get_inner_reference()
- will be 'i * C_i + j * C_j + C'.
- We try to substitute the variables of the offset expression
- with initial_condition of the corresponding access_fn in the loop.
- 'i' cannot be substituted, since its access_fn in the inner loop is i. 'j'
- will be substituted with 3.
-
- Example 2
- for (j = 3; j < N; j++)
- a[j].b[5][j] = 0;
-
- Here the offset expression (j * C_j + C) will not contain variables after
- substitution of j=3 (3*C_j + C).
-
- Misalignment can be calculated only if all the variables can be
- substituted with constants, otherwise, we record maximum possible alignment
- in ALIGNED_TO. In Example 1, since 'i' cannot be substituted,
- MISALIGNMENT will be NULL_TREE, and the biggest divider of C_i (a power of
- 2) will be recorded in ALIGNED_TO.
-
- In Example 2, MISALIGNMENT will be the value of 3*C_j + C in bytes, and
- ALIGNED_TO will be NULL_TREE.
- */
- tree misalignment;
- tree aligned_to;
-
- /* The type of the data-ref. */
- enum data_ref_type type;
+ /* Alias information for the data reference. */
+ struct dr_alias alias;
};
typedef struct data_reference *data_reference_p;
#define DR_STMT(DR) (DR)->stmt
#define DR_REF(DR) (DR)->ref
-#define DR_BASE_OBJECT(DR) (DR)->object_info.base_object
-#define DR_TYPE(DR) (DR)->type
-#define DR_ACCESS_FNS(DR)\
- (DR_TYPE(DR) == ARRAY_REF_TYPE ? \
- (DR)->object_info.access_fns : (DR)->first_location.access_fns)
+#define DR_BASE_OBJECT(DR) (DR)->indices.base_object
+#define DR_ACCESS_FNS(DR) (DR)->indices.access_fns
#define DR_ACCESS_FN(DR, I) VEC_index (tree, DR_ACCESS_FNS (DR), I)
#define DR_NUM_DIMENSIONS(DR) VEC_length (tree, DR_ACCESS_FNS (DR))
#define DR_IS_READ(DR) (DR)->is_read
-#define DR_BASE_ADDRESS(DR) (DR)->first_location.base_address
-#define DR_OFFSET(DR) (DR)->first_location.offset
-#define DR_INIT(DR) (DR)->first_location.init
-#define DR_STEP(DR) (DR)->first_location.step
-#define DR_MEMTAG(DR) (DR)->memtag
-#define DR_ALIGNED_TO(DR) (DR)->aligned_to
-#define DR_OFFSET_MISALIGNMENT(DR) (DR)->misalignment
-#define DR_PTR_INFO(DR) (DR)->ptr_info
-#define DR_SUBVARS(DR) (DR)->subvars
-
-#define DR_ACCESS_FNS_ADDR(DR) \
- (DR_TYPE(DR) == ARRAY_REF_TYPE ? \
- &((DR)->object_info.access_fns) : &((DR)->first_location.access_fns))
-#define DR_SET_ACCESS_FNS(DR, ACC_FNS) \
-{ \
- if (DR_TYPE(DR) == ARRAY_REF_TYPE) \
- (DR)->object_info.access_fns = ACC_FNS; \
- else \
- (DR)->first_location.access_fns = ACC_FNS; \
-}
-#define DR_FREE_ACCESS_FNS(DR) \
-{ \
- if (DR_TYPE(DR) == ARRAY_REF_TYPE) \
- VEC_free (tree, heap, (DR)->object_info.access_fns); \
- else \
- VEC_free (tree, heap, (DR)->first_location.access_fns); \
-}
+#define DR_BASE_ADDRESS(DR) (DR)->innermost.base_address
+#define DR_OFFSET(DR) (DR)->innermost.offset
+#define DR_INIT(DR) (DR)->innermost.init
+#define DR_STEP(DR) (DR)->innermost.step
+#define DR_SYMBOL_TAG(DR) (DR)->alias.symbol_tag
+#define DR_PTR_INFO(DR) (DR)->alias.ptr_info
+#define DR_VOPS(DR) (DR)->alias.vops
+#define DR_ALIGNED_TO(DR) (DR)->innermost.aligned_to
enum data_dependence_direction {
dir_positive,
dir_independent
};
+/* The description of the grid of iterations that overlap. At most
+ two loops are considered at the same time just now, hence at most
+ two functions are needed. For each of the functions, we store
+ the vector of coefficients, f[0] + x * f[1] + y * f[2] + ...,
+ where x, y, ... are variables. */
+
+#define MAX_DIM 2
+
+/* Special values of N. */
+#define NO_DEPENDENCE 0
+#define NOT_KNOWN (MAX_DIM + 1)
+#define CF_NONTRIVIAL_P(CF) ((CF)->n != NO_DEPENDENCE && (CF)->n != NOT_KNOWN)
+#define CF_NOT_KNOWN_P(CF) ((CF)->n == NOT_KNOWN)
+#define CF_NO_DEPENDENCE_P(CF) ((CF)->n == NO_DEPENDENCE)
+
+typedef VEC (tree, heap) *affine_fn;
+
+typedef struct
+{
+ unsigned n;
+ affine_fn fns[MAX_DIM];
+} conflict_function;
+
/* What is a 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
{
/* A description of the iterations for which the elements are
accessed twice. */
- tree conflicting_iterations_in_a;
- tree conflicting_iterations_in_b;
+ conflict_function *conflicting_iterations_in_a;
+ conflict_function *conflicting_iterations_in_b;
/* This field stores the information about the iteration domain
validity of the dependence relation. */
#define SUB_LAST_CONFLICT(SUB) SUB->last_conflict
#define SUB_DISTANCE(SUB) SUB->distance
-typedef struct loop *loop_p;
-DEF_VEC_P(loop_p);
-DEF_VEC_ALLOC_P (loop_p, heap);
-
/* A data_dependence_relation represents a relation between two
data_references A and B. */
a distance vector. */
bool affine_p;
+ /* Set to true when the dependence relation is on the same data
+ access. */
+ bool self_reference_p;
+
/* A "yes/no/maybe" field for the dependence relation:
- when "ARE_DEPENDENT == NULL_TREE", there exist a dependence
/* The analyzed loop nest. */
VEC (loop_p, heap) *loop_nest;
+ /* An index in loop_nest for the innermost loop that varies for
+ this data dependence relation. */
+ unsigned inner_loop;
+
/* The classic direction vector. */
VEC (lambda_vector, heap) *dir_vects;
/* The classic distance vector. */
VEC (lambda_vector, heap) *dist_vects;
+
+ /* Is the dependence reversed with respect to the lexicographic order? */
+ bool reversed_p;
};
typedef struct data_dependence_relation *ddr_p;
/* The size of the direction/distance vectors: the number of loops in
the loop nest. */
#define DDR_NB_LOOPS(DDR) (VEC_length (loop_p, DDR_LOOP_NEST (DDR)))
+#define DDR_INNER_LOOP(DDR) DDR->inner_loop
+#define DDR_SELF_REFERENCE(DDR) DDR->self_reference_p
#define DDR_DIST_VECTS(DDR) ((DDR)->dist_vects)
#define DDR_DIR_VECTS(DDR) ((DDR)->dir_vects)
VEC_index (lambda_vector, DDR_DIR_VECTS (DDR), I)
#define DDR_DIST_VECT(DDR, I) \
VEC_index (lambda_vector, DDR_DIST_VECTS (DDR), I)
+#define DDR_REVERSED_P(DDR) DDR->reversed_p
\f
DEF_VEC_ALLOC_O (data_ref_loc, heap);
bool get_references_in_stmt (tree, VEC (data_ref_loc, heap) **);
-extern tree find_data_references_in_loop (struct loop *,
- VEC (data_reference_p, heap) **);
+void dr_analyze_innermost (struct data_reference *);
extern void compute_data_dependences_for_loop (struct loop *, bool,
VEC (data_reference_p, heap) **,
VEC (ddr_p, heap) **);
extern void dump_data_dependence_relation (FILE *,
struct data_dependence_relation *);
extern void dump_data_dependence_relations (FILE *, VEC (ddr_p, heap) *);
+extern void debug_data_dependence_relations (VEC (ddr_p, heap) *);
extern void dump_data_dependence_direction (FILE *,
enum data_dependence_direction);
extern void free_dependence_relation (struct data_dependence_relation *);
extern void free_dependence_relations (VEC (ddr_p, heap) *);
+extern void free_data_ref (data_reference_p);
extern void free_data_refs (VEC (data_reference_p, heap) *);
-extern struct data_reference *analyze_array (tree, tree, bool);
+struct data_reference *create_data_ref (struct loop *, tree, tree, bool);
+bool find_loop_nest (struct loop *, VEC (loop_p, heap) **);
+void compute_all_dependences (VEC (data_reference_p, heap) *,
+ VEC (ddr_p, heap) **, VEC (loop_p, heap) *, bool);
+
+/* 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;
+}
+
+/* Return true when DDR is an anti-dependence relation. */
+
+static inline bool
+ddr_is_anti_dependent (ddr_p ddr)
+{
+ return (DDR_ARE_DEPENDENT (ddr) == NULL_TREE
+ && DR_IS_READ (DDR_A (ddr))
+ && !DR_IS_READ (DDR_B (ddr))
+ && !same_access_functions (ddr));
+}
+
+/* Return true when DEPENDENCE_RELATIONS contains an anti-dependence. */
+
+static inline bool
+ddrs_have_anti_deps (VEC (ddr_p, heap) *dependence_relations)
+{
+ unsigned i;
+ ddr_p ddr;
+
+ for (i = 0; VEC_iterate (ddr_p, dependence_relations, i, ddr); i++)
+ if (ddr_is_anti_dependent (ddr))
+ return true;
+
+ return false;
+}
+
+/* Return the dependence level for the DDR relation. */
+
+static inline unsigned
+ddr_dependence_level (ddr_p ddr)
+{
+ unsigned vector;
+ unsigned level = 0;
+
+ if (DDR_DIST_VECTS (ddr))
+ level = dependence_level (DDR_DIST_VECT (ddr, 0), DDR_NB_LOOPS (ddr));
+
+ for (vector = 1; vector < DDR_NUM_DIST_VECTS (ddr); vector++)
+ level = MIN (level, dependence_level (DDR_DIST_VECT (ddr, vector),
+ DDR_NB_LOOPS (ddr)));
+ return level;
+}
+
+\f
+
+/* A Reduced Dependence Graph (RDG) vertex representing a statement. */
+typedef struct rdg_vertex
+{
+ /* The statement represented by this vertex. */
+ tree stmt;
+
+ /* True when the statement contains a write to memory. */
+ bool has_mem_write;
+
+ /* True when the statement contains a read from memory. */
+ bool has_mem_reads;
+} *rdg_vertex_p;
+
+#define RDGV_STMT(V) ((struct rdg_vertex *) ((V)->data))->stmt
+#define RDGV_HAS_MEM_WRITE(V) ((struct rdg_vertex *) ((V)->data))->has_mem_write
+#define RDGV_HAS_MEM_READS(V) ((struct rdg_vertex *) ((V)->data))->has_mem_reads
+#define RDG_STMT(RDG, I) RDGV_STMT (&(RDG->vertices[I]))
+#define RDG_MEM_WRITE_STMT(RDG, I) RDGV_HAS_MEM_WRITE (&(RDG->vertices[I]))
+#define RDG_MEM_READS_STMT(RDG, I) RDGV_HAS_MEM_READS (&(RDG->vertices[I]))
+
+void dump_rdg_vertex (FILE *, struct graph *, int);
+void debug_rdg_vertex (struct graph *, int);
+void dump_rdg_component (FILE *, struct graph *, int, bitmap);
+void debug_rdg_component (struct graph *, int);
+void dump_rdg (FILE *, struct graph *);
+void debug_rdg (struct graph *);
+void dot_rdg (struct graph *);
+int rdg_vertex_for_stmt (struct graph *, tree);
+/* Data dependence type. */
+
+enum rdg_dep_type
+{
+ /* Read After Write (RAW). */
+ flow_dd = 'f',
+
+ /* Write After Read (WAR). */
+ anti_dd = 'a',
+
+ /* Write After Write (WAW). */
+ output_dd = 'o',
+
+ /* Read After Read (RAR). */
+ input_dd = 'i'
+};
+
+/* Dependence information attached to an edge of the RDG. */
+
+typedef struct rdg_edge
+{
+ /* Type of the dependence. */
+ enum rdg_dep_type type;
+
+ /* Levels of the dependence: the depth of the loops that
+ carry the dependence. */
+ unsigned level;
+} *rdg_edge_p;
+
+#define RDGE_TYPE(E) ((struct rdg_edge *) ((E)->data))->type
+#define RDGE_LEVEL(E) ((struct rdg_edge *) ((E)->data))->level
+
+struct graph *build_rdg (struct loop *);
+void free_rdg (struct graph *);
/* Return the index of the variable VAR in the LOOP_NEST array. */
return var_index;
}
+void stores_from_loop (struct loop *, VEC (tree, heap) **);
+void remove_similar_memory_refs (VEC (tree, heap) **);
+bool rdg_defs_used_in_other_loops_p (struct graph *, int);
+bool have_similar_memory_accesses (tree, tree);
+
+/* Determines whether RDG vertices V1 and V2 access to similar memory
+ locations, in which case they have to be in the same partition. */
+
+static inline bool
+rdg_has_similar_memory_accesses (struct graph *rdg, int v1, int v2)
+{
+ return have_similar_memory_accesses (RDG_STMT (rdg, v1),
+ RDG_STMT (rdg, v2));
+}
+
/* In lambda-code.c */
bool lambda_transform_legal_p (lambda_trans_matrix, int, VEC (ddr_p, heap) *);
+/* In tree-data-refs.c */
+void split_constant_offset (tree , tree *, tree *);
+
#endif /* GCC_TREE_DATA_REF_H */
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