/* SSA Dominator optimizations for trees
- Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
+ Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
Free Software Foundation, Inc.
Contributed by Diego Novillo <dnovillo@redhat.com>
Computing and storing the edge equivalences instead of creating
them on-demand can save significant amounts of time, particularly
- for pathological cases involving switch statements.
+ for pathological cases involving switch statements.
These structures live for a single iteration of the dominator
optimizer in the edge's AUX field. At the end of an iteration we
enum tree_code subcode = gimple_assign_rhs_code (stmt);
expr->type = NULL_TREE;
-
+
switch (get_gimple_rhs_class (subcode))
{
case GIMPLE_SINGLE_RHS:
if (gimple_call_flags (stmt) & (ECF_CONST | ECF_PURE))
expr->ops.call.pure = true;
- else
+ else
expr->ops.call.pure = false;
expr->ops.call.nargs = nargs;
initialize_expr_from_cond (tree cond, struct hashable_expr *expr)
{
expr->type = boolean_type_node;
-
+
if (COMPARISON_CLASS_P (cond))
{
expr->kind = EXPR_BINARY;
return true;
}
-
+
default:
gcc_unreachable ();
}
val = iterative_hash_expr (expr->ops.call.args[i], val);
}
break;
-
+
default:
gcc_unreachable ();
}
print_generic_expr (stream, element->lhs, 0);
fprintf (stream, " = ");
}
-
+
switch (element->expr.kind)
{
case EXPR_SINGLE:
}
}
-/* Jump threading, redundancy elimination and const/copy propagation.
+/* Jump threading, redundancy elimination and const/copy propagation.
This pass may expose new symbols that need to be renamed into SSA. For
every new symbol exposed, its corresponding bit will be set in
for jump threading; this may include back edges that are not part of
a single loop. */
mark_dfs_back_edges ();
-
+
/* Recursively walk the dominator tree optimizing statements. */
walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
/* Free asserted bitmaps and stacks. */
BITMAP_FREE (need_eh_cleanup);
-
+
VEC_free (expr_hash_elt_t, heap, avail_exprs_stack);
VEC_free (tree, heap, const_and_copies_stack);
-
+
/* Free the value-handle array. */
threadedge_finalize_values ();
ssa_name_values = NULL;
return flag_tree_dom != 0;
}
-struct gimple_opt_pass pass_dominator =
+struct gimple_opt_pass pass_dominator =
{
{
GIMPLE_PASS,
/* Remove all the expressions made available in this block. */
while (VEC_length (expr_hash_elt_t, avail_exprs_stack) > 0)
{
- struct expr_hash_elt element;
expr_hash_elt_t victim = VEC_pop (expr_hash_elt_t, avail_exprs_stack);
+ void **slot;
if (victim == NULL)
break;
- element = *victim;
-
/* This must precede the actual removal from the hash table,
as ELEMENT and the table entry may share a call argument
vector which will be freed during removal. */
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "<<<< ");
- print_expr_hash_elt (dump_file, &element);
+ print_expr_hash_elt (dump_file, victim);
}
- htab_remove_elt_with_hash (avail_exprs, &element, element.hash);
+ slot = htab_find_slot_with_hash (avail_exprs,
+ victim, victim->hash, NO_INSERT);
+ gcc_assert (slot && *slot == (void *) victim);
+ htab_clear_slot (avail_exprs, slot);
}
}
record_equivalences_from_phis (basic_block bb)
{
gimple_stmt_iterator gsi;
-
+
for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
{
gimple phi = gsi_stmt (gsi);
/* Build a cond_equivalence record indicating that the comparison
CODE holds between operands OP0 and OP1. */
-
+
static void
build_and_record_new_cond (enum tree_code code,
tree op0, tree op1,
/* Returns true when STMT is a simple iv increment. It detects the
following situation:
-
+
i_1 = phi (..., i_2)
i_2 = i_1 +/- ... */
}
/* CONST_AND_COPIES is a table which maps an SSA_NAME to the current
- known value for that SSA_NAME (or NULL if no value is known).
+ known value for that SSA_NAME (or NULL if no value is known).
Propagate values from CONST_AND_COPIES into the PHI nodes of the
successors of BB. */
}
opt_stats.num_re++;
-
+
if (assigns_var_p
&& !useless_type_conversion_p (expr_type, TREE_TYPE (cached_lhs)))
cached_lhs = fold_convert (expr_type, cached_lhs);
&& gimple_assign_single_p (stmt))
{
tree rhs = gimple_assign_rhs1 (stmt);
-
+
/* If the RHS of the assignment is a constant or another variable that
may be propagated, register it in the CONST_AND_COPIES table. We
do not need to record unwind data for this, since this is a true
}
/* CONST_AND_COPIES is a table which maps an SSA_NAME to the current
- known value for that SSA_NAME (or NULL if no value is known).
+ known value for that SSA_NAME (or NULL if no value is known).
Propagate values from CONST_AND_COPIES into the uses, vuses and
vdef_ops of STMT. */
}
/* Optimize the statement pointed to by iterator SI.
-
+
We try to perform some simplistic global redundancy elimination and
constant propagation:
bool modified_p = false;
old_stmt = stmt = gsi_stmt (si);
-
+
if (gimple_code (stmt) == GIMPLE_COND)
canonicalize_comparison (stmt);
-
+
update_stmt_if_modified (stmt);
opt_stats.num_stmts++;
if (fold_stmt (&si))
{
stmt = gsi_stmt (si);
+ gimple_set_modified (stmt, true);
if (dump_file && (dump_flags & TDF_DETAILS))
{
if (may_optimize_p)
{
- eliminate_redundant_computations (&si);
- stmt = gsi_stmt (si);
if (gimple_code (stmt) == GIMPLE_CALL)
{
/* Resolve __builtin_constant_p. If it hasn't been
stmt = gsi_stmt (si);
}
}
+
+ update_stmt_if_modified (stmt);
+ eliminate_redundant_computations (&si);
+ stmt = gsi_stmt (si);
}
/* Record any additional equivalences created by this statement. */
where it goes. If that is the case, then mark the CFG as altered.
This will cause us to later call remove_unreachable_blocks and
- cleanup_tree_cfg when it is safe to do so. It is not safe to
+ cleanup_tree_cfg when it is safe to do so. It is not safe to
clean things up here since removal of edges and such can trigger
the removal of PHI nodes, which in turn can release SSA_NAMEs to
the manager.
if (gimple_modified_p (stmt) || modified_p)
{
tree val = NULL;
-
- update_stmt (stmt);
+
+ update_stmt_if_modified (stmt);
if (gimple_code (stmt) == GIMPLE_COND)
val = fold_binary_loc (gimple_location (stmt),
void **slot;
tree lhs;
tree temp;
- struct expr_hash_elt *element = XNEW (struct expr_hash_elt);
+ struct expr_hash_elt element;
/* Get LHS of assignment or call, else NULL_TREE. */
lhs = gimple_get_lhs (stmt);
- initialize_hash_element (stmt, lhs, element);
+ initialize_hash_element (stmt, lhs, &element);
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "LKUP ");
- print_expr_hash_elt (dump_file, element);
+ print_expr_hash_elt (dump_file, &element);
}
/* Don't bother remembering constant assignments and copy operations.
Constants and copy operations are handled by the constant/copy propagator
in optimize_stmt. */
- if (element->expr.kind == EXPR_SINGLE
- && (TREE_CODE (element->expr.ops.single.rhs) == SSA_NAME
- || is_gimple_min_invariant (element->expr.ops.single.rhs)))
- {
- free (element);
- return NULL_TREE;
- }
+ if (element.expr.kind == EXPR_SINGLE
+ && (TREE_CODE (element.expr.ops.single.rhs) == SSA_NAME
+ || is_gimple_min_invariant (element.expr.ops.single.rhs)))
+ return NULL_TREE;
/* Finally try to find the expression in the main expression hash table. */
- slot = htab_find_slot_with_hash (avail_exprs, element, element->hash,
+ slot = htab_find_slot_with_hash (avail_exprs, &element, element.hash,
(insert ? INSERT : NO_INSERT));
if (slot == NULL)
- {
- free (element);
- return NULL_TREE;
- }
+ return NULL_TREE;
if (*slot == NULL)
{
- *slot = (void *) element;
+ struct expr_hash_elt *element2 = XNEW (struct expr_hash_elt);
+ *element2 = element;
+ element2->stamp = element2;
+ *slot = (void *) element2;
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "2>>> ");
- print_expr_hash_elt (dump_file, element);
+ print_expr_hash_elt (dump_file, element2);
}
- VEC_safe_push (expr_hash_elt_t, heap, avail_exprs_stack, element);
+ VEC_safe_push (expr_hash_elt_t, heap, avail_exprs_stack, element2);
return NULL_TREE;
}
lhs = temp;
}
- free (element);
-
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "FIND: ");
if (arg == lhs)
continue;
+ else if (!arg)
+ break;
else if (!val)
val = arg;
- else if (!operand_equal_p (arg, val, 0))
+ else if (arg == val)
+ continue;
+ /* We bring in some of operand_equal_p not only to speed things
+ up, but also to avoid crashing when dereferencing the type of
+ a released SSA name. */
+ else if (TREE_CODE (val) != TREE_CODE (arg)
+ || TREE_CODE (val) == SSA_NAME
+ || !operand_equal_p (arg, val, 0))
break;
}
return (i == gimple_phi_num_args (phi) ? val : NULL);
nodes as well in an effort to pick up secondary optimization
opportunities. */
-static void
+static void
propagate_rhs_into_lhs (gimple stmt, tree lhs, tree rhs, bitmap interesting_names)
{
/* First verify that propagation is valid and isn't going to move a
fprintf (dump_file, "'\n");
}
- /* Walk over every use of LHS and try to replace the use with RHS.
+ /* Walk over every use of LHS and try to replace the use with RHS.
At this point the only reason why such a propagation would not
be successful would be if the use occurs in an ASM_EXPR. */
FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs)
into debug stmts will occur then. */
if (gimple_debug_bind_p (use_stmt))
continue;
-
+
/* It's not always safe to propagate into an ASM_EXPR. */
if (gimple_code (use_stmt) == GIMPLE_ASM
&& ! may_propagate_copy_into_asm (lhs))
continue;
}
- /* From this point onward we are propagating into a
+ /* From this point onward we are propagating into a
real statement. Folding may (or may not) be possible,
we may expose new operands, expose dead EH edges,
etc. */
}
}
- /* Ensure there is nothing else to do. */
+ /* Ensure there is nothing else to do. */
gcc_assert (!all || has_zero_uses (lhs));
/* If we were able to propagate away all uses of LHS, then
A set bit indicates that the statement or PHI node which
defines the SSA_NAME should be (re)examined to determine if
it has become a degenerate PHI or trivial const/copy propagation
- opportunity.
+ opportunity.
Experiments have show we generally get better compilation
time behavior with bitmaps rather than sbitmaps. */
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_cleanup_cfg
- | TODO_dump_func
+ | TODO_dump_func
| TODO_ggc_collect
| TODO_verify_ssa
| TODO_verify_stmts
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