/* Data references and dependences detectors.
- Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
+ Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
Free Software Foundation, Inc.
Contributed by Sebastian Pop <pop@cri.ensmp.fr>
#include "tree-pass.h"
#include "langhooks.h"
#include "tree-affine.h"
+#include "params.h"
static struct datadep_stats
{
dr_analyze_indices (struct data_reference *dr, loop_p nest, loop_p loop)
{
VEC (tree, heap) *access_fns = NULL;
- tree ref, *aref, op;
+ tree ref, op;
tree base, off, access_fn;
basic_block before_loop;
return;
}
- ref = unshare_expr (DR_REF (dr));
+ ref = DR_REF (dr);
before_loop = block_before_loop (nest);
/* REALPART_EXPR and IMAGPART_EXPR can be handled like accesses
}
/* Analyze access functions of dimensions we know to be independent. */
- aref = &ref;
- while (handled_component_p (*aref))
+ while (handled_component_p (ref))
{
- if (TREE_CODE (*aref) == ARRAY_REF)
+ if (TREE_CODE (ref) == ARRAY_REF)
{
- op = TREE_OPERAND (*aref, 1);
+ op = TREE_OPERAND (ref, 1);
access_fn = analyze_scalar_evolution (loop, op);
access_fn = instantiate_scev (before_loop, loop, access_fn);
VEC_safe_push (tree, heap, access_fns, access_fn);
- /* For ARRAY_REFs the base is the reference with the index replaced
- by zero if we can not strip it as the outermost component. */
- if (*aref == ref)
- {
- *aref = TREE_OPERAND (*aref, 0);
- continue;
- }
- else
- TREE_OPERAND (*aref, 1) = build_int_cst (TREE_TYPE (op), 0);
}
+ else if (TREE_CODE (ref) == COMPONENT_REF
+ && TREE_CODE (TREE_TYPE (TREE_OPERAND (ref, 0))) == RECORD_TYPE)
+ {
+ /* For COMPONENT_REFs of records (but not unions!) use the
+ FIELD_DECL offset as constant access function so we can
+ disambiguate a[i].f1 and a[i].f2. */
+ tree off = component_ref_field_offset (ref);
+ off = size_binop (PLUS_EXPR,
+ size_binop (MULT_EXPR,
+ fold_convert (bitsizetype, off),
+ bitsize_int (BITS_PER_UNIT)),
+ DECL_FIELD_BIT_OFFSET (TREE_OPERAND (ref, 1)));
+ VEC_safe_push (tree, heap, access_fns, off);
+ }
+ else
+ /* If we have an unhandled component we could not translate
+ to an access function stop analyzing. We have determined
+ our base object in this case. */
+ break;
- aref = &TREE_OPERAND (*aref, 0);
+ ref = TREE_OPERAND (ref, 0);
}
/* If the address operand of a MEM_REF base has an evolution in the
analyzed nest, add it as an additional independent access-function. */
- if (TREE_CODE (*aref) == MEM_REF)
+ if (TREE_CODE (ref) == MEM_REF)
{
- op = TREE_OPERAND (*aref, 0);
+ op = TREE_OPERAND (ref, 0);
access_fn = analyze_scalar_evolution (loop, op);
access_fn = instantiate_scev (before_loop, loop, access_fn);
if (TREE_CODE (access_fn) == POLYNOMIAL_CHREC)
{
tree orig_type;
+ tree memoff = TREE_OPERAND (ref, 1);
base = initial_condition (access_fn);
orig_type = TREE_TYPE (base);
STRIP_USELESS_TYPE_CONVERSION (base);
split_constant_offset (base, &base, &off);
/* Fold the MEM_REF offset into the evolutions initial
value to make more bases comparable. */
- if (!integer_zerop (TREE_OPERAND (*aref, 1)))
+ if (!integer_zerop (memoff))
{
off = size_binop (PLUS_EXPR, off,
- fold_convert (ssizetype,
- TREE_OPERAND (*aref, 1)));
- TREE_OPERAND (*aref, 1)
- = build_int_cst (TREE_TYPE (TREE_OPERAND (*aref, 1)), 0);
+ fold_convert (ssizetype, memoff));
+ memoff = build_int_cst (TREE_TYPE (memoff), 0);
}
access_fn = chrec_replace_initial_condition
(access_fn, fold_convert (orig_type, off));
- *aref = fold_build2_loc (EXPR_LOCATION (*aref),
- MEM_REF, TREE_TYPE (*aref),
- base, TREE_OPERAND (*aref, 1));
+ /* ??? This is still not a suitable base object for
+ dr_may_alias_p - the base object needs to be an
+ access that covers the object as whole. With
+ an evolution in the pointer this cannot be
+ guaranteed.
+ As a band-aid, mark the access so we can special-case
+ it in dr_may_alias_p. */
+ ref = fold_build2_loc (EXPR_LOCATION (ref),
+ MEM_REF, TREE_TYPE (ref),
+ base, memoff);
+ DR_UNCONSTRAINED_BASE (dr) = true;
VEC_safe_push (tree, heap, access_fns, access_fn);
}
}
+ else if (DECL_P (ref))
+ {
+ /* Canonicalize DR_BASE_OBJECT to MEM_REF form. */
+ ref = build2 (MEM_REF, TREE_TYPE (ref),
+ build_fold_addr_expr (ref),
+ build_int_cst (reference_alias_ptr_type (ref), 0));
+ }
DR_BASE_OBJECT (dr) = ref;
DR_ACCESS_FNS (dr) = access_fns;
return false;
}
+ /* If we had an evolution in a MEM_REF BASE_OBJECT we do not know
+ the size of the base-object. So we cannot do any offset/overlap
+ based analysis but have to rely on points-to information only. */
+ if (TREE_CODE (addr_a) == MEM_REF
+ && DR_UNCONSTRAINED_BASE (a))
+ {
+ if (TREE_CODE (addr_b) == MEM_REF
+ && DR_UNCONSTRAINED_BASE (b))
+ return ptr_derefs_may_alias_p (TREE_OPERAND (addr_a, 0),
+ TREE_OPERAND (addr_b, 0));
+ else
+ return ptr_derefs_may_alias_p (TREE_OPERAND (addr_a, 0),
+ build_fold_addr_expr (addr_b));
+ }
+ else if (TREE_CODE (addr_b) == MEM_REF
+ && DR_UNCONSTRAINED_BASE (b))
+ return ptr_derefs_may_alias_p (build_fold_addr_expr (addr_a),
+ TREE_OPERAND (addr_b, 0));
+
+ /* Otherwise DR_BASE_OBJECT is an access that covers the whole object
+ that is being subsetted in the loop nest. */
if (DR_IS_WRITE (a) && DR_IS_WRITE (b))
return refs_output_dependent_p (addr_a, addr_b);
else if (DR_IS_READ (a) && DR_IS_WRITE (b))
return res;
}
- /* When the references are exactly the same, don't spend time doing
- the data dependence tests, just initialize the ddr and return. */
+ /* The case where the references are exactly the same. */
if (operand_equal_p (DR_REF (a), DR_REF (b), 0))
{
+ if (loop_nest
+ && !object_address_invariant_in_loop_p (VEC_index (loop_p, loop_nest, 0),
+ DR_BASE_OBJECT (a)))
+ {
+ DDR_ARE_DEPENDENT (res) = chrec_dont_know;
+ return res;
+ }
DDR_AFFINE_P (res) = true;
DDR_ARE_DEPENDENT (res) = NULL_TREE;
DDR_SUBSCRIPTS (res) = VEC_alloc (subscript_p, heap, DR_NUM_DIMENSIONS (a));
DDR_LOOP_NEST (res) = loop_nest;
DDR_INNER_LOOP (res) = 0;
DDR_SELF_REFERENCE (res) = true;
- compute_self_dependence (res);
+ 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;
+ VEC_safe_push (subscript_p, heap, DDR_SUBSCRIPTS (res), subscript);
+ }
return res;
}
return double_int_to_tree (unsigned_type_node, nit);
}
+/* Determine whether the CHREC is always positive/negative. If the expression
+ cannot be statically analyzed, return false, otherwise set the answer into
+ VALUE. */
+
+static bool
+chrec_is_positive (tree chrec, bool *value)
+{
+ bool value0, value1, value2;
+ tree end_value, nb_iter;
+
+ switch (TREE_CODE (chrec))
+ {
+ case POLYNOMIAL_CHREC:
+ if (!chrec_is_positive (CHREC_LEFT (chrec), &value0)
+ || !chrec_is_positive (CHREC_RIGHT (chrec), &value1))
+ return false;
+
+ /* FIXME -- overflows. */
+ if (value0 == value1)
+ {
+ *value = value0;
+ return true;
+ }
+
+ /* Otherwise the chrec is under the form: "{-197, +, 2}_1",
+ and the proof consists in showing that the sign never
+ changes during the execution of the loop, from 0 to
+ loop->nb_iterations. */
+ if (!evolution_function_is_affine_p (chrec))
+ return false;
+
+ nb_iter = number_of_latch_executions (get_chrec_loop (chrec));
+ if (chrec_contains_undetermined (nb_iter))
+ return false;
+
+#if 0
+ /* TODO -- If the test is after the exit, we may decrease the number of
+ iterations by one. */
+ if (after_exit)
+ nb_iter = chrec_fold_minus (type, nb_iter, build_int_cst (type, 1));
+#endif
+
+ end_value = chrec_apply (CHREC_VARIABLE (chrec), chrec, nb_iter);
+
+ if (!chrec_is_positive (end_value, &value2))
+ return false;
+
+ *value = value0;
+ return value0 == value1;
+
+ case INTEGER_CST:
+ switch (tree_int_cst_sgn (chrec))
+ {
+ case -1:
+ *value = false;
+ break;
+ case 1:
+ *value = true;
+ break;
+ default:
+ return false;
+ }
+ return true;
+
+ default:
+ return false;
+ }
+}
+
+
/* Analyze a SIV (Single Index Variable) subscript where CHREC_A is a
constant, and CHREC_B is an affine function. *OVERLAPS_A and
*OVERLAPS_B are initialized to the functions that describe the
chrec_b = chrec_convert (type, chrec_b, NULL);
difference = chrec_fold_minus (type, initial_condition (chrec_b), chrec_a);
+ /* Special case overlap in the first iteration. */
+ if (integer_zerop (difference))
+ {
+ *overlaps_a = conflict_fn (1, affine_fn_cst (integer_zero_node));
+ *overlaps_b = conflict_fn (1, affine_fn_cst (integer_zero_node));
+ *last_conflicts = integer_one_node;
+ return;
+ }
+
if (!chrec_is_positive (initial_condition (difference), &value0))
{
if (dump_file && (dump_flags & TDF_DETAILS))
unsigned int i;
tree last_conflicts;
struct subscript *subscript;
+ tree res = NULL_TREE;
for (i = 0; VEC_iterate (subscript_p, DDR_SUBSCRIPTS (ddr), i, subscript);
i++)
&overlaps_a, &overlaps_b,
&last_conflicts, loop_nest);
+ if (SUB_CONFLICTS_IN_A (subscript))
+ free_conflict_function (SUB_CONFLICTS_IN_A (subscript));
+ if (SUB_CONFLICTS_IN_B (subscript))
+ free_conflict_function (SUB_CONFLICTS_IN_B (subscript));
+
+ SUB_CONFLICTS_IN_A (subscript) = overlaps_a;
+ SUB_CONFLICTS_IN_B (subscript) = overlaps_b;
+ SUB_LAST_CONFLICT (subscript) = last_conflicts;
+
+ /* If there is any undetermined conflict function we have to
+ give a conservative answer in case we cannot prove that
+ no dependence exists when analyzing another subscript. */
if (CF_NOT_KNOWN_P (overlaps_a)
|| CF_NOT_KNOWN_P (overlaps_b))
{
- finalize_ddr_dependent (ddr, chrec_dont_know);
- dependence_stats.num_dependence_undetermined++;
- free_conflict_function (overlaps_a);
- free_conflict_function (overlaps_b);
- return false;
+ res = chrec_dont_know;
+ continue;
}
+ /* When there is a subscript with no dependence we can stop. */
else if (CF_NO_DEPENDENCE_P (overlaps_a)
|| CF_NO_DEPENDENCE_P (overlaps_b))
{
- finalize_ddr_dependent (ddr, chrec_known);
- dependence_stats.num_dependence_independent++;
- free_conflict_function (overlaps_a);
- free_conflict_function (overlaps_b);
- return false;
- }
-
- else
- {
- if (SUB_CONFLICTS_IN_A (subscript))
- free_conflict_function (SUB_CONFLICTS_IN_A (subscript));
- if (SUB_CONFLICTS_IN_B (subscript))
- free_conflict_function (SUB_CONFLICTS_IN_B (subscript));
-
- SUB_CONFLICTS_IN_A (subscript) = overlaps_a;
- SUB_CONFLICTS_IN_B (subscript) = overlaps_b;
- SUB_LAST_CONFLICT (subscript) = last_conflicts;
+ res = chrec_known;
+ break;
}
}
- return true;
+ if (res == NULL_TREE)
+ return true;
+
+ if (res == chrec_known)
+ dependence_stats.num_dependence_independent++;
+ else
+ dependence_stats.num_dependence_undetermined++;
+ finalize_ddr_dependent (ddr, res);
+ return false;
}
/* Computes the conflicting iterations in LOOP_NEST, and initialize DDR. */
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "(compute_affine_dependence\n");
- fprintf (dump_file, " (stmt_a = \n");
- print_gimple_stmt (dump_file, DR_STMT (dra), 0, 0);
- fprintf (dump_file, ")\n (stmt_b = \n");
- print_gimple_stmt (dump_file, DR_STMT (drb), 0, 0);
- fprintf (dump_file, ")\n");
+ fprintf (dump_file, " stmt_a: ");
+ print_gimple_stmt (dump_file, DR_STMT (dra), 0, TDF_SLIM);
+ fprintf (dump_file, " stmt_b: ");
+ print_gimple_stmt (dump_file, DR_STMT (drb), 0, TDF_SLIM);
}
/* Analyze only when the dependence relation is not yet known. */
- if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE
- && !DDR_SELF_REFERENCE (ddr))
+ if (DDR_ARE_DEPENDENT (ddr) == NULL_TREE)
{
dependence_stats.num_dependence_tests++;
}
if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, ")\n");
-}
-
-/* This computes the dependence relation for the same data
- reference into DDR. */
-
-void
-compute_self_dependence (struct data_dependence_relation *ddr)
-{
- unsigned int i;
- struct subscript *subscript;
-
- if (DDR_ARE_DEPENDENT (ddr) != NULL_TREE)
- return;
-
- for (i = 0; VEC_iterate (subscript_p, DDR_SUBSCRIPTS (ddr), i, subscript);
- i++)
{
- if (SUB_CONFLICTS_IN_A (subscript))
- free_conflict_function (SUB_CONFLICTS_IN_A (subscript));
- if (SUB_CONFLICTS_IN_B (subscript))
- free_conflict_function (SUB_CONFLICTS_IN_B (subscript));
-
- /* The accessed index overlaps for each iteration. */
- SUB_CONFLICTS_IN_A (subscript)
- = conflict_fn (1, affine_fn_cst (integer_zero_node));
- SUB_CONFLICTS_IN_B (subscript)
- = conflict_fn (1, affine_fn_cst (integer_zero_node));
- SUB_LAST_CONFLICT (subscript) = chrec_dont_know;
+ if (DDR_ARE_DEPENDENT (ddr) == chrec_known)
+ fprintf (dump_file, ") -> no dependence\n");
+ else if (DDR_ARE_DEPENDENT (ddr) == chrec_dont_know)
+ fprintf (dump_file, ") -> dependence analysis failed\n");
+ else
+ fprintf (dump_file, ")\n");
}
-
- /* The distance vector is the zero vector. */
- save_dist_v (ddr, lambda_vector_new (DDR_NB_LOOPS (ddr)));
- save_dir_v (ddr, lambda_vector_new (DDR_NB_LOOPS (ddr)));
}
/* Compute in DEPENDENCE_RELATIONS the data dependence graph for all
the data references in DATAREFS, in the LOOP_NEST. When
COMPUTE_SELF_AND_RR is FALSE, don't compute read-read and self
- relations. */
+ relations. Return true when successful, i.e. data references number
+ is small enough to be handled. */
-void
+bool
compute_all_dependences (VEC (data_reference_p, heap) *datarefs,
VEC (ddr_p, heap) **dependence_relations,
VEC (loop_p, heap) *loop_nest,
struct data_reference *a, *b;
unsigned int i, j;
+ if ((int) VEC_length (data_reference_p, datarefs)
+ > PARAM_VALUE (PARAM_LOOP_MAX_DATAREFS_FOR_DATADEPS))
+ {
+ struct data_dependence_relation *ddr;
+
+ /* Insert a single relation into dependence_relations:
+ chrec_dont_know. */
+ ddr = initialize_data_dependence_relation (NULL, NULL, loop_nest);
+ VEC_safe_push (ddr_p, heap, *dependence_relations, ddr);
+ return false;
+ }
+
FOR_EACH_VEC_ELT (data_reference_p, datarefs, i, a)
for (j = i + 1; VEC_iterate (data_reference_p, datarefs, j, b); j++)
if (DR_IS_WRITE (a) || DR_IS_WRITE (b) || compute_self_and_rr)
{
ddr = initialize_data_dependence_relation (a, a, loop_nest);
VEC_safe_push (ddr_p, heap, *dependence_relations, ddr);
- compute_self_dependence (ddr);
+ if (loop_nest)
+ compute_affine_dependence (ddr, VEC_index (loop_p, loop_nest, 0));
}
+
+ return true;
}
/* Stores the locations of memory references in STMT to REFERENCES. Returns
if ((stmt_code == GIMPLE_CALL
&& !(gimple_call_flags (stmt) & (ECF_CONST | ECF_PURE)))
|| (stmt_code == GIMPLE_ASM
- && gimple_asm_volatile_p (stmt)))
+ && (gimple_asm_volatile_p (stmt) || gimple_vuse (stmt))))
clobbers_memory = true;
if (!gimple_vuse (stmt))
TODO: This function should be made smarter so that it can handle address
arithmetic as if they were array accesses, etc. */
-tree
+static tree
find_data_references_in_loop (struct loop *loop,
VEC (data_reference_p, heap) **datarefs)
{
dependences. */
if (!loop
|| !find_loop_nest (loop, loop_nest)
- || find_data_references_in_loop (loop, datarefs) == chrec_dont_know)
- {
- struct data_dependence_relation *ddr;
-
- /* Insert a single relation into dependence_relations:
- chrec_dont_know. */
- ddr = initialize_data_dependence_relation (NULL, NULL, *loop_nest);
- VEC_safe_push (ddr_p, heap, *dependence_relations, ddr);
- res = false;
- }
- else
- compute_all_dependences (*datarefs, dependence_relations, *loop_nest,
- compute_self_and_read_read_dependences);
+ || find_data_references_in_loop (loop, datarefs) == chrec_dont_know
+ || !compute_all_dependences (*datarefs, dependence_relations, *loop_nest,
+ compute_self_and_read_read_dependences))
+ res = false;
if (dump_file && (dump_flags & TDF_STATS))
{
if (find_data_references_in_bb (NULL, bb, datarefs) == chrec_dont_know)
return false;
- compute_all_dependences (*datarefs, dependence_relations, NULL,
- compute_self_and_read_read_dependences);
- return true;
+ return compute_all_dependences (*datarefs, dependence_relations, NULL,
+ compute_self_and_read_read_dependences);
}
/* Entry point (for testing only). Analyze all the data references
VEC (data_reference_p, heap) **datarefs)
{
struct graph *rdg = NULL;
- VEC (gimple, heap) *stmts = VEC_alloc (gimple, heap, 10);
- compute_data_dependences_for_loop (loop, false, loop_nest, datarefs,
- dependence_relations);
-
- if (known_dependences_p (*dependence_relations))
+ if (compute_data_dependences_for_loop (loop, false, loop_nest, datarefs,
+ dependence_relations)
+ && known_dependences_p (*dependence_relations))
{
+ VEC (gimple, heap) *stmts = VEC_alloc (gimple, heap, 10);
stmts_from_loop (loop, &stmts);
rdg = build_empty_rdg (VEC_length (gimple, stmts));
create_rdg_vertices (rdg, stmts);
create_rdg_edges (rdg, *dependence_relations);
+ VEC_free (gimple, heap, stmts);
}
- VEC_free (gimple, heap, stmts);
return rdg;
}
bool
stmt_with_adjacent_zero_store_dr_p (gimple stmt)
{
- tree op0, op1;
+ tree lhs, rhs;
bool res;
struct data_reference *dr;
if (!stmt
|| !gimple_vdef (stmt)
- || !is_gimple_assign (stmt)
- || !gimple_assign_single_p (stmt)
- || !(op1 = gimple_assign_rhs1 (stmt))
- || !(integer_zerop (op1) || real_zerop (op1)))
+ || !gimple_assign_single_p (stmt))
+ return false;
+
+ lhs = gimple_assign_lhs (stmt);
+ rhs = gimple_assign_rhs1 (stmt);
+
+ /* If this is a bitfield store bail out. */
+ if (TREE_CODE (lhs) == COMPONENT_REF
+ && DECL_BIT_FIELD (TREE_OPERAND (lhs, 1)))
+ return false;
+
+ if (!(integer_zerop (rhs) || real_zerop (rhs)))
return false;
dr = XCNEW (struct data_reference);
- op0 = gimple_assign_lhs (stmt);
DR_STMT (dr) = stmt;
- DR_REF (dr) = op0;
+ DR_REF (dr) = lhs;
res = dr_analyze_innermost (dr, loop_containing_stmt (stmt))
- && stride_of_unit_type_p (DR_STEP (dr), TREE_TYPE (op0));
+ && stride_of_unit_type_p (DR_STEP (dr), TREE_TYPE (lhs));
free_data_ref (dr);
return res;
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