expressions/constants/values. */
typedef struct value_set_node
{
+ /* An expression. */
tree expr;
+
+ /* A pointer to the next element of the value set. */
struct value_set_node *next;
} *value_set_node_t;
-/* A value set, which is the head of the linked list, and we also keep
- the tail because we have to append for the topolofical sort. */
+/* A value set. This is a singly linked list of value_set_node
+ elements with a possible bitmap that tells us what values exist in
+ the set. This set must be kept in topologically sorted order. */
typedef struct value_set
{
+ /* The head of the list. Used for iterating over the list in
+ order. */
value_set_node_t head;
+
+ /* The tail of the list. Used for tail insertions, which are
+ necessary to keep the set in topologically sorted order because
+ of how the set is built. */
value_set_node_t tail;
+
+ /* The length of the list. */
size_t length;
+
+ /* True if the set is indexed, which means it contains a backing
+ bitmap for quick determination of whether certain values exist in the
+ set. */
bool indexed;
+
+ /* The bitmap of values that exist in the set. May be NULL in an
+ empty or non-indexed set. */
bitmap values;
} *value_set_t;
/* All of the following sets, except for TMP_GEN, are indexed.
TMP_GEN is only ever iterated over, we never check what values
exist in it. */
+
typedef struct bb_value_sets
{
+ /* The EXP_GEN set, which represents expressions/values generated in
+ a basic block. */
value_set_t exp_gen;
+
+ /* The PHI_GEN set, which represents PHI results generated in a
+ basic block. */
value_set_t phi_gen;
+
+ /* The TMP_GEN set, which represents results/temporaries genererated
+ in a basic block. IE the LHS of an expression. */
value_set_t tmp_gen;
+
+ /* The AVAIL_OUT set, which represents which values are available in
+ a given basic block. */
value_set_t avail_out;
+
+ /* The ANTIC_IN set, which represents which values are anticiptable
+ in a given basic block. */
value_set_t antic_in;
+
+ /* The NEW_SETS set, which is used during insertion to augment the
+ AVAIL_OUT set of blocks with the new insertions performed during
+ the current iteration. */
value_set_t new_sets;
} *bb_value_sets_t;
#define ANTIC_IN(BB) ((bb_value_sets_t) ((BB)->aux))->antic_in
#define NEW_SETS(BB) ((bb_value_sets_t) ((BB)->aux))->new_sets
+/* This structure is used to keep track of statistics on what
+ optimization PRE was able to perform. */
static struct
{
+ /* The number of RHS computations eliminated by PRE. */
int eliminations;
+
+ /* The number of new expressions/temporaries generated by PRE. */
int insertions;
+
+ /* The number of new PHI nodes added by PRE. */
int phis;
} pre_stats;
static void add_to_value (tree, tree);
static value_set_t set_new (bool);
static bool is_undefined_value (tree);
+static bool expressions_equal_p (tree, tree);
/* We can add and remove elements and entries to and from sets
and hash tables, so we use alloc pools for them. */
static alloc_pool unary_node_pool;
/* The value table that maps expressions to values. */
+
static htab_t value_table;
/* The phi_translate_table caches phi translations for a given
expression and predecessor. */
+
static htab_t phi_translate_table;
+/* Compare two expressions E1 and E2 and return true if they are
+ equal. */
+
+static bool
+expressions_equal_p (tree e1, tree e2)
+{
+ tree te1, te2;
+
+ if (e1 == e2)
+ return true;
+
+ te1 = TREE_TYPE (e1);
+ te2 = TREE_TYPE (e2);
+
+ if (TREE_CODE (e1) == TREE_CODE (e2)
+ && (te1 == te2 || lang_hooks.types_compatible_p (te1, te2))
+ && operand_equal_p (e1, e2, 0))
+ return true;
+ return false;
+}
/* Map expressions to values. These are simple pairs of expressions
and the values they represent. To find the value represented by
} *val_expr_pair_t;
-/* Hash a {v,e} pair. We really only hash the expression. */
+/* Hash a {v,e} pair that is pointed to by P.
+ The hashcode is cached in the val_expr_pair, so we just return
+ that. */
static hashval_t
val_expr_pair_hash (const void *p)
}
-/* Are {e2,v2} and {e1,v1} the same? Again, only the expression
- matters. */
+/* Given two val_expr_pair_t's, return true if they represent the same
+ expression, false otherwise.
+ P1 and P2 should point to the val_expr_pair_t's to be compared. */
static int
val_expr_pair_expr_eq (const void *p1, const void *p2)
{
const val_expr_pair_t ve1 = (val_expr_pair_t) p1;
const val_expr_pair_t ve2 = (val_expr_pair_t) p2;
- tree e1 = ve1->e;
- tree e2 = ve2->e;
- tree te1;
- tree te2;
- if (e1 == e2)
- return true;
- te1 = TREE_TYPE (e1);
- te2 = TREE_TYPE (e2);
- if (TREE_CODE (e1) == TREE_CODE (e2)
- && (te1 == te2 || lang_hooks.types_compatible_p (te1, te2))
- && operand_equal_p (e1, e2, 0))
+ if (expressions_equal_p (ve1->e, ve2->e))
return true;
-
+
return false;
}
/* Get the value handle of EXPR. This is the only correct way to get
- the value handle for a "thing". */
+ the value handle for a "thing".
+ Returns NULL if the value handle does not exist. */
tree
get_value_handle (tree expr)
}
-/* Set the value handle for E to V */
+/* Set the value handle for expression E to value V */
void
set_value_handle (tree e, tree v)
typedef struct expr_pred_trans_d
{
+ /* The expression. */
tree e;
+
+ /* The predecessor block along which we translated the expression. */
basic_block pred;
+
+ /* The value that resulted from the translation. */
tree v;
+
+ /* The hashcode for the expression, pred pair. This is cached for
+ speed reasons. */
hashval_t hashcode;
} *expr_pred_trans_t;
return ve->hashcode;
}
-/* Return true if two phi translation table entries are the same. */
+/* Return true if two phi translation table entries are the same.
+ P1 and P2 should point to the expr_pred_trans_t's to be compared.*/
static int
expr_pred_trans_eq (const void *p1, const void *p2)
{
const expr_pred_trans_t ve1 = (expr_pred_trans_t) p1;
const expr_pred_trans_t ve2 = (expr_pred_trans_t) p2;
- tree e1 = ve1->e;
- tree e2 = ve2->e;
basic_block b1 = ve1->pred;
basic_block b2 = ve2->pred;
- tree te1;
- tree te2;
+
+ /* If they are not translations for the same basic block, they can't
+ be equal. */
if (b1 != b2)
return false;
- if (e1 == e2)
- return true;
-
- te1 = TREE_TYPE (e1);
- te2 = TREE_TYPE (e2);
-
- if (TREE_CODE (e1) == TREE_CODE (e2)
- && (te1 == te2 || lang_hooks.types_compatible_p (te1, te2))
- && operand_equal_p (e1, e2, 0))
+ /* If they are for the same basic block, determine if the
+ expressions are equal. */
+ if (expressions_equal_p (ve1->e, ve2->e))
return true;
return false;
}
-/* Search in the phi translation table for the translation of E in
- PRED. Return the translated value, if found, NULL otherwise. */
+/* Search in the phi translation table for the translation of
+ expression E in basic block PRED. Return the translated value, if
+ found, NULL otherwise. */
static inline tree
phi_trans_lookup (tree e, basic_block pred)
{
void **slot;
- struct expr_pred_trans_d ugly;
- ugly.e = e;
- ugly.pred = pred;
- ugly.hashcode = iterative_hash_expr (e, (unsigned long) pred);
- slot = htab_find_slot_with_hash (phi_translate_table, &ugly, ugly.hashcode,
+ struct expr_pred_trans_d ept;
+ ept.e = e;
+ ept.pred = pred;
+ ept.hashcode = iterative_hash_expr (e, (unsigned long) pred);
+ slot = htab_find_slot_with_hash (phi_translate_table, &ept, ept.hashcode,
NO_INSERT);
if (!slot)
return NULL;
}
-/* Add the tuple mapping {e, pred}->v to the phi translation table. */
+/* Add the tuple mapping from {expression E, basic block PRED} to
+ value V, to the phi translation table. */
static inline void
phi_trans_add (tree e, tree v, basic_block pred)
lookup (htab_t table, tree e)
{
void **slot;
- struct val_expr_pair_d ugly = {NULL, NULL, 0};
- ugly.e = e;
- ugly.hashcode = iterative_hash_expr (e,0);
- slot = htab_find_slot_with_hash (table, &ugly, ugly.hashcode, NO_INSERT);
+ struct val_expr_pair_d vep = {NULL, NULL, 0};
+ vep.e = e;
+ vep.hashcode = iterative_hash_expr (e,0);
+ slot = htab_find_slot_with_hash (table, &vep, vep.hashcode, NO_INSERT);
if (!slot)
return NULL_TREE;
else
return ((val_expr_pair_t) *slot)->v;
}
-/* Add E to the expression set of V. */
+/* Add expression E to the expression set of value V. */
static inline void
add_to_value (tree v, tree e)
#endif
}
-/* Insert E into TABLE with value V, and add E to the value set for V. */
+/* Insert E into TABLE with value V, and add expression E to the value
+ set for value V. */
static inline void
add (htab_t table, tree e, tree v)
}
+/* A unique counter that is incremented every time we create a new
+ value. */
static int pre_uid;
-/* Create a new value handle for EXPR. */
+/* Create a new value handle for expression EXPR. */
+
static tree
create_new_value (tree expr)
{
return a;
}
-/* Like lookup, but adds V as the value for E if E does not have a value. */
+/* Like lookup, but creates a new value for expression E if E doesn't
+ already have a value.
+ Return the existing/created value for E. */
+
static inline tree
lookup_or_add (htab_t table, tree e)
{
}
-/* Search in the bitmap for SET to see if E exists. */
+/* Return true if value V exists in the bitmap for SET. */
static inline bool
-value_exists_in_set_bitmap (value_set_t set, tree e)
+value_exists_in_set_bitmap (value_set_t set, tree v)
{
- if (TREE_CODE (e) != VAR_DECL)
+ if (TREE_CODE (v) != VAR_DECL)
abort ();
if (!set->values)
return false;
- return bitmap_bit_p (set->values, get_var_ann (e)->uid);
+ return bitmap_bit_p (set->values, get_var_ann (v)->uid);
}
-/* Remove E from the bitmap for SET. */
+/* Remove value V from the bitmap for SET. */
static void
-value_remove_from_set_bitmap (value_set_t set, tree e)
+value_remove_from_set_bitmap (value_set_t set, tree v)
{
- if (TREE_CODE (e) != VAR_DECL)
+ if (TREE_CODE (v) != VAR_DECL)
abort ();
#ifdef ENABLE_CHECKING
if (!set->indexed)
#endif
if (!set->values)
return;
- bitmap_clear_bit (set->values, get_var_ann (e)->uid);
+ bitmap_clear_bit (set->values, get_var_ann (v)->uid);
}
-/* Insert the value number E into the bitmap of values existing in
+/* Insert the value number V into the bitmap of values existing in
SET. */
static inline void
-value_insert_into_set_bitmap (value_set_t set, tree e)
+value_insert_into_set_bitmap (value_set_t set, tree v)
{
- if (TREE_CODE (e) != VAR_DECL)
+ if (TREE_CODE (v) != VAR_DECL)
abort ();
#ifdef ENABLE_CHECKING
if (!set->indexed)
set->values = BITMAP_GGC_ALLOC ();
bitmap_clear (set->values);
}
- bitmap_set_bit (set->values, get_var_ann (e)->uid);
+ bitmap_set_bit (set->values, get_var_ann (v)->uid);
}
/* Create a new set. */
node = node->next)
{
print_generic_expr (outfile, node->expr, 0);
+
+ fprintf (outfile, " (");
+ print_generic_expr (outfile, get_value_handle (node->expr), 0);
+ fprintf (outfile, ") ");
+
if (node->next)
fprintf (outfile, ", ");
}
return NULL;
if (newop1 != oldop1)
{
- newexpr = pool_alloc (unary_node_pool);
+ newexpr = pool_alloc (unary_node_pool);
memcpy (newexpr, expr, tree_size (expr));
- create_expr_ann (newexpr);
+ create_expr_ann (newexpr);
TREE_OPERAND (newexpr, 0) = get_value_handle (newop1);
lookup_or_add (value_table, newexpr);
expr = newexpr;
return false;
}
-/* Clean the set of expressions that are no longer valid in the
- specified set. This means expressions that are made up of values
- we have no leaders for in the current set, etc. */
+/* Clean the set of expressions that are no longer valid in SET. This
+ means expressions that are made up of values we have no leaders for
+ in SET. */
static void
clean (value_set_t set)
value_insert_into_set (ANTIC_IN (block), node->expr);
}
clean (ANTIC_IN (block));
+
if (!set_equal (old, ANTIC_IN (block)))
changed = true;
tree *avail;
tree val;
bool by_some = false;
+ bool cant_insert = false;
bool all_same = true;
tree first_s = NULL;
edge pred;
basic_block bprime;
tree eprime;
- bool cant_insert = false;
val = get_value_handle (node->expr);
if (set_contains_value (PHI_GEN (block), val))
else
{
avail[bprime->index] = edoubleprime;
- by_some = true;
+ by_some = true;
if (first_s == NULL)
first_s = edoubleprime;
else if (first_s != edoubleprime)
abort ();
}
}
-
+ /* If we can insert it, it's not the same value
+ already existing along every predecessor, and
+ it's defined by some predecessor, it is
+ partially redundant. */
if (!cant_insert && !all_same && by_some)
{
- tree temp;
tree type = TREE_TYPE (avail[block->pred->src->index]);
+ tree temp;
tree v;
if (dump_file && (dump_flags & TDF_DETAILS))
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