#include "tree-ssa-threadedge.h"
#include "tree-ssa-dom.h"
#include "inchash.h"
+#include "gimplify.h"
/* This file implements optimizations on the dominator tree. */
marker. */
typedef struct expr_hash_elt * expr_hash_elt_t;
-static vec<expr_hash_elt_t> avail_exprs_stack;
+static vec<std::pair<expr_hash_elt_t, expr_hash_elt_t> > avail_exprs_stack;
/* Structure for entries in the expression hash table. */
/* The expression (rhs) we want to record. */
struct hashable_expr expr;
- /* The stmt pointer if this element corresponds to a statement. */
- gimple stmt;
+ /* The virtual operand associated with the nearest dominating stmt
+ loading from or storing to expr. */
+ tree vop;
/* The hash value for RHS. */
hashval_t hash;
inline bool
expr_elt_hasher::equal (const value_type &p1, const compare_type &p2)
{
- gimple stmt1 = p1->stmt;
const struct hashable_expr *expr1 = &p1->expr;
const struct expr_hash_elt *stamp1 = p1->stamp;
- gimple stmt2 = p2->stmt;
const struct hashable_expr *expr2 = &p2->expr;
const struct expr_hash_elt *stamp2 = p2->stamp;
if (stamp1 == stamp2)
return true;
- /* FIXME tuples:
- We add stmts to a hash table and them modify them. To detect the case
- that we modify a stmt and then search for it, we assume that the hash
- is always modified by that change.
- We have to fully check why this doesn't happen on trunk or rewrite
- this in a more reliable (and easier to understand) way. */
- if (((const struct expr_hash_elt *)p1)->hash
- != ((const struct expr_hash_elt *)p2)->hash)
+ if (p1->hash != p2->hash)
return false;
/* In case of a collision, both RHS have to be identical and have the
same VUSE operands. */
if (hashable_expr_equal_p (expr1, expr2)
&& types_compatible_p (expr1->type, expr2->type))
- {
- /* Note that STMT1 and/or STMT2 may be NULL. */
- return ((stmt1 ? gimple_vuse (stmt1) : NULL_TREE)
- == (stmt2 ? gimple_vuse (stmt2) : NULL_TREE));
- }
+ return true;
return false;
}
gcc_unreachable ();
element->lhs = lhs;
- element->stmt = stmt;
+ element->vop = gimple_vuse (stmt);
element->hash = avail_expr_hash (element);
element->stamp = element;
}
{
element->expr = *expr;
element->lhs = lhs;
- element->stmt = NULL;
+ element->vop = NULL_TREE;
element->hash = avail_expr_hash (element);
element->stamp = element;
}
static void
print_expr_hash_elt (FILE * stream, const struct expr_hash_elt *element)
{
- if (element->stmt)
- fprintf (stream, "STMT ");
- else
- fprintf (stream, "COND ");
+ fprintf (stream, "STMT ");
if (element->lhs)
{
}
break;
}
- fprintf (stream, "\n");
- if (element->stmt)
+ if (element->vop)
{
- fprintf (stream, " ");
- print_gimple_stmt (stream, element->stmt, 0, 0);
+ fprintf (stream, " with ");
+ print_generic_expr (stream, element->vop, 0);
}
+
+ fprintf (stream, "\n");
}
/* Delete variable sized pieces of the expr_hash_elt ELEMENT. */
/* Remove all the expressions made available in this block. */
while (avail_exprs_stack.length () > 0)
{
- expr_hash_elt_t victim = avail_exprs_stack.pop ();
+ std::pair<expr_hash_elt_t, expr_hash_elt_t> victim
+ = avail_exprs_stack.pop ();
expr_hash_elt **slot;
- if (victim == NULL)
+ if (victim.first == NULL)
break;
/* This must precede the actual removal from the hash table,
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "<<<< ");
- print_expr_hash_elt (dump_file, victim);
+ print_expr_hash_elt (dump_file, victim.first);
}
- slot = avail_exprs->find_slot (victim, NO_INSERT);
- gcc_assert (slot && *slot == victim);
- avail_exprs->clear_slot (slot);
+ slot = avail_exprs->find_slot (victim.first, NO_INSERT);
+ gcc_assert (slot && *slot == victim.first);
+ if (victim.second != NULL)
+ {
+ free_expr_hash_elt (*slot);
+ *slot = victim.second;
+ }
+ else
+ avail_exprs->clear_slot (slot);
}
}
/* Push a marker on both stacks so we can unwind the tables back to their
current state. */
- avail_exprs_stack.safe_push (NULL);
+ avail_exprs_stack.safe_push
+ (std::pair<expr_hash_elt_t, expr_hash_elt_t> (NULL, NULL));
const_and_copies_stack.safe_push (NULL_TREE);
/* Traversing E may result in equivalences we can utilize. */
print_expr_hash_elt (dump_file, element);
}
- avail_exprs_stack.safe_push (element);
+ avail_exprs_stack.safe_push
+ (std::pair<expr_hash_elt_t, expr_hash_elt_t> (element, NULL));
}
else
free_expr_hash_elt (element);
/* Push a marker on the stacks of local information so that we know how
far to unwind when we finalize this block. */
- avail_exprs_stack.safe_push (NULL);
+ avail_exprs_stack.safe_push
+ (std::pair<expr_hash_elt_t, expr_hash_elt_t> (NULL, NULL));
const_and_copies_stack.safe_push (NULL_TREE);
record_equivalences_from_incoming_edge (bb);
/* Create equivalences from redundant PHIs. PHIs are only truly
redundant when they exist in the same block, so push another
marker and unwind right afterwards. */
- avail_exprs_stack.safe_push (NULL);
+ avail_exprs_stack.safe_push
+ (std::pair<expr_hash_elt_t, expr_hash_elt_t> (NULL, NULL));
for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
eliminate_redundant_computations (&gsi);
remove_local_expressions_from_table ();
}
}
+ /* Make sure we can propagate &x + CST. */
+ if (lhs_code == SSA_NAME
+ && gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR
+ && TREE_CODE (gimple_assign_rhs1 (stmt)) == ADDR_EXPR
+ && TREE_CODE (gimple_assign_rhs2 (stmt)) == INTEGER_CST)
+ {
+ tree op0 = gimple_assign_rhs1 (stmt);
+ tree op1 = gimple_assign_rhs2 (stmt);
+ tree new_rhs
+ = build_fold_addr_expr (fold_build2 (MEM_REF,
+ TREE_TYPE (TREE_TYPE (op0)),
+ unshare_expr (op0),
+ fold_convert (ptr_type_node,
+ op1)));
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "==== ASGN ");
+ print_generic_expr (dump_file, lhs, 0);
+ fprintf (dump_file, " = ");
+ print_generic_expr (dump_file, new_rhs, 0);
+ fprintf (dump_file, "\n");
+ }
+
+ set_ssa_name_value (lhs, new_rhs);
+ }
+
/* A memory store, even an aliased store, creates a useful
equivalence. By exchanging the LHS and RHS, creating suitable
vops and recording the result in the available expression table,
}
}
+/* Helper for walk_non_aliased_vuses. Determine if we arrived at
+ the desired memory state. */
+
+static void *
+vuse_eq (ao_ref *, tree vuse1, unsigned int cnt, void *data)
+{
+ tree vuse2 = (tree) data;
+ if (vuse1 == vuse2)
+ return data;
+
+ /* This bounds the stmt walks we perform on reference lookups
+ to O(1) instead of O(N) where N is the number of dominating
+ stores leading to a candidate. We re-use the SCCVN param
+ for this as it is basically the same complexity. */
+ if (cnt > (unsigned) PARAM_VALUE (PARAM_SCCVN_MAX_ALIAS_QUERIES_PER_ACCESS))
+ return (void *)-1;
+
+ return NULL;
+}
+
/* Search for an existing instance of STMT in the AVAIL_EXPRS table.
If found, return its LHS. Otherwise insert STMT in the table and
return NULL_TREE.
print_expr_hash_elt (dump_file, element2);
}
- avail_exprs_stack.safe_push (element2);
+ avail_exprs_stack.safe_push
+ (std::pair<expr_hash_elt_t, expr_hash_elt_t> (element2, NULL));
return NULL_TREE;
}
- else
- free_expr_hash_elt_contents (&element);
+
+ /* If we found a redundant memory operation do an alias walk to
+ check if we can re-use it. */
+ if (gimple_vuse (stmt) != (*slot)->vop)
+ {
+ tree vuse1 = (*slot)->vop;
+ tree vuse2 = gimple_vuse (stmt);
+ /* If we have a load of a register and a candidate in the
+ hash with vuse1 then try to reach its stmt by walking
+ up the virtual use-def chain using walk_non_aliased_vuses.
+ But don't do this when removing expressions from the hash. */
+ ao_ref ref;
+ if (!(vuse1 && vuse2
+ && gimple_assign_single_p (stmt)
+ && TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME
+ && (ao_ref_init (&ref, gimple_assign_rhs1 (stmt)), true)
+ && walk_non_aliased_vuses (&ref, vuse2,
+ vuse_eq, NULL, vuse1) != NULL))
+ {
+ struct expr_hash_elt *element2 = XNEW (struct expr_hash_elt);
+ *element2 = element;
+ element2->stamp = element2;
+
+ /* Insert the expr into the hash by replacing the current
+ entry and recording the value to restore in the
+ aval_exprs_stack. */
+ avail_exprs_stack.safe_push (std::make_pair (element2, *slot));
+ *slot = element2;
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "2>>> ");
+ print_expr_hash_elt (dump_file, *slot);
+ }
+ return NULL_TREE;
+ }
+ }
+
+ free_expr_hash_elt_contents (&element);
/* Extract the LHS of the assignment so that it can be used as the current
definition of another variable. */
- lhs = ((struct expr_hash_elt *)*slot)->lhs;
+ lhs = (*slot)->lhs;
/* See if the LHS appears in the CONST_AND_COPIES table. If it does, then
use the value from the const_and_copies table. */
static hashval_t
avail_expr_hash (const void *p)
{
- gimple stmt = ((const struct expr_hash_elt *)p)->stmt;
const struct hashable_expr *expr = &((const struct expr_hash_elt *)p)->expr;
- tree vuse;
inchash::hash hstate;
inchash::add_hashable_expr (expr, hstate);
- /* If the hash table entry is not associated with a statement, then we
- can just hash the expression and not worry about virtual operands
- and such. */
- if (!stmt)
- return hstate.end ();
-
- /* Add the SSA version numbers of the vuse operand. This is important
- because compound variables like arrays are not renamed in the
- operands. Rather, the rename is done on the virtual variable
- representing all the elements of the array. */
- if ((vuse = gimple_vuse (stmt)))
- inchash::add_expr (vuse, hstate);
-
return hstate.end ();
}
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