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tree-ssa-dom.c (update_rhs_and_lookup_avail_expr): Kill.

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* tree-ssa-dom.c (update_rhs_and_lookup_avail_expr): Kill.
	(simplify_rhs_and_lookup_avail_expr): Kill.  Remnants moved
	into tree-ssa-forwprop.c.
	(eliminate_redundant_computations): Do not call
	simplify_rhs_and_lookup_avail_expr anymore.
	* tree-ssa-forwprop.c (simplify_not_neg_expr): New function
	extracted from remnants of simplify_rhs_and_lookup_avail_expr.
	(tree_ssa_forward_propagate_single_use_vars): Call
	simplify_not_neg_expr appropriately.

From-SVN: r108711
This commit is contained in:
Jeff Law 2005-12-17 00:18:35 -07:00 committed by Jeff Law
parent b15e733f3c
commit 471eeb830d
3 changed files with 75 additions and 119 deletions
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12
gcc/ChangeLog
View File

@ -1,3 +1,15 @@
2005-12-16 Jeff Law <law@redhat.com>
* tree-ssa-dom.c (update_rhs_and_lookup_avail_expr): Kill.
(simplify_rhs_and_lookup_avail_expr): Kill. Remnants moved
into tree-ssa-forwprop.c.
(eliminate_redundant_computations): Do not call
simplify_rhs_and_lookup_avail_expr anymore.
* tree-ssa-forwprop.c (simplify_not_neg_expr): New function
extracted from remnants of simplify_rhs_and_lookup_avail_expr.
(tree_ssa_forward_propagate_single_use_vars): Call
simplify_not_neg_expr appropriately.
2005-12-16 Bernd Trog <berndtrog@yahoo.com>
PR target/20016

117
gcc/tree-ssa-dom.c
View File

@ -273,8 +273,6 @@ static void htab_statistics (FILE *, htab_t);
static void record_cond (tree, tree);
static void record_const_or_copy (tree, tree);
static void record_equality (tree, tree);
static tree update_rhs_and_lookup_avail_expr (tree, tree, bool);
static tree simplify_rhs_and_lookup_avail_expr (tree, int);
static tree simplify_cond_and_lookup_avail_expr (tree, stmt_ann_t, int);
static tree simplify_switch_and_lookup_avail_expr (tree, int);
static tree find_equivalent_equality_comparison (tree);
@ -1795,51 +1793,6 @@ simple_iv_increment_p (tree stmt)
return false;
}
/* STMT is a MODIFY_EXPR for which we were unable to find RHS in the
hash tables. Try to simplify the RHS using whatever equivalences
we may have recorded.
If we are able to simplify the RHS, then lookup the simplified form in
the hash table and return the result. Otherwise return NULL. */
static tree
simplify_rhs_and_lookup_avail_expr (tree stmt, int insert)
{
tree rhs = TREE_OPERAND (stmt, 1);
enum tree_code rhs_code = TREE_CODE (rhs);
tree result = NULL;
/* If we have lhs = ~x, look and see if we earlier had x = ~y.
In which case we can change this statement to be lhs = y.
Which can then be copy propagated.
Similarly for negation. */
if ((rhs_code == BIT_NOT_EXPR || rhs_code == NEGATE_EXPR)
&& TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
{
/* Get the definition statement for our RHS. */
tree rhs_def_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0));
/* See if the RHS_DEF_STMT has the same form as our statement. */
if (TREE_CODE (rhs_def_stmt) == MODIFY_EXPR
&& TREE_CODE (TREE_OPERAND (rhs_def_stmt, 1)) == rhs_code)
{
tree rhs_def_operand;
rhs_def_operand = TREE_OPERAND (TREE_OPERAND (rhs_def_stmt, 1), 0);
/* Verify that RHS_DEF_OPERAND is a suitable SSA variable. */
if (TREE_CODE (rhs_def_operand) == SSA_NAME
&& ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs_def_operand))
result = update_rhs_and_lookup_avail_expr (stmt,
rhs_def_operand,
insert);
}
}
return result;
}
/* COND is a condition of the form:
x == const or x != const
@ -2516,15 +2469,9 @@ eliminate_redundant_computations (tree stmt, stmt_ann_t ann)
/* Check if the expression has been computed before. */
cached_lhs = lookup_avail_expr (stmt, insert);
/* If this is an assignment and the RHS was not in the hash table,
then try to simplify the RHS and lookup the new RHS in the
hash table. */
if (! cached_lhs && TREE_CODE (stmt) == MODIFY_EXPR)
cached_lhs = simplify_rhs_and_lookup_avail_expr (stmt, insert);
/* Similarly if this is a COND_EXPR and we did not find its
expression in the hash table, simplify the condition and
try again. */
else if (! cached_lhs && TREE_CODE (stmt) == COND_EXPR)
/* If this is a COND_EXPR and we did not find its expression in
the hash table, simplify the condition and try again. */
if (! cached_lhs && TREE_CODE (stmt) == COND_EXPR)
cached_lhs = simplify_cond_and_lookup_avail_expr (stmt, ann, insert);
/* Similarly for a SWITCH_EXPR. */
else if (!cached_lhs && TREE_CODE (stmt) == SWITCH_EXPR)
@ -2991,64 +2938,6 @@ optimize_stmt (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
VEC_safe_push (tree, heap, stmts_to_rescan, bsi_stmt (si));
}
/* Replace the RHS of STMT with NEW_RHS. If RHS can be found in the
available expression hashtable, then return the LHS from the hash
table.
If INSERT is true, then we also update the available expression
hash table to account for the changes made to STMT. */
static tree
update_rhs_and_lookup_avail_expr (tree stmt, tree new_rhs, bool insert)
{
tree cached_lhs = NULL;
/* Remove the old entry from the hash table. */
if (insert)
{
struct expr_hash_elt element;
initialize_hash_element (stmt, NULL, &element);
htab_remove_elt_with_hash (avail_exprs, &element, element.hash);
}
/* Now update the RHS of the assignment. */
TREE_OPERAND (stmt, 1) = new_rhs;
/* Now lookup the updated statement in the hash table. */
cached_lhs = lookup_avail_expr (stmt, insert);
/* We have now called lookup_avail_expr twice with two different
versions of this same statement, once in optimize_stmt, once here.
We know the call in optimize_stmt did not find an existing entry
in the hash table, so a new entry was created. At the same time
this statement was pushed onto the AVAIL_EXPRS_STACK vector.
If this call failed to find an existing entry on the hash table,
then the new version of this statement was entered into the
hash table. And this statement was pushed onto BLOCK_AVAIL_EXPR
for the second time. So there are two copies on BLOCK_AVAIL_EXPRs
If this call succeeded, we still have one copy of this statement
on the BLOCK_AVAIL_EXPRs vector.
For both cases, we need to pop the most recent entry off the
BLOCK_AVAIL_EXPRs vector. For the case where we never found this
statement in the hash tables, that will leave precisely one
copy of this statement on BLOCK_AVAIL_EXPRs. For the case where
we found a copy of this statement in the second hash table lookup
we want _no_ copies of this statement in BLOCK_AVAIL_EXPRs. */
if (insert)
VEC_pop (tree, avail_exprs_stack);
/* And make sure we record the fact that we modified this
statement. */
mark_stmt_modified (stmt);
return cached_lhs;
}
/* 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.

65
gcc/tree-ssa-forwprop.c
View File

@ -703,6 +703,41 @@ forward_propagate_addr_expr (tree stmt)
return all;
}
/* If we have lhs = ~x (STMT), look and see if earlier we had x = ~y.
If so, we can change STMT into lhs = y which can later be copy
propagated. Similarly for negation.
This could trivially be formulated as a forward propagation
to immediate uses. However, we already had an implementation
from DOM which used backward propagation via the use-def links.
It turns out that backward propagation is actually faster as
there's less work to do for each NOT/NEG expression we find.
Backwards propagation needs to look at the statement in a single
backlink. Forward propagation needs to look at potentially more
than one forward link. */
static void
simplify_not_neg_expr (tree stmt)
{
tree rhs = TREE_OPERAND (stmt, 1);
tree rhs_def_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0));
/* See if the RHS_DEF_STMT has the same form as our statement. */
if (TREE_CODE (rhs_def_stmt) == MODIFY_EXPR
&& TREE_CODE (TREE_OPERAND (rhs_def_stmt, 1)) == TREE_CODE (rhs))
{
tree rhs_def_operand = TREE_OPERAND (TREE_OPERAND (rhs_def_stmt, 1), 0);
/* Verify that RHS_DEF_OPERAND is a suitable SSA_NAME. */
if (TREE_CODE (rhs_def_operand) == SSA_NAME
&& ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs_def_operand))
{
TREE_OPERAND (stmt, 1) = rhs_def_operand;
update_stmt (stmt);
}
}
}
/* Main entry point for the forward propagation optimizer. */
@ -724,12 +759,32 @@ tree_ssa_forward_propagate_single_use_vars (void)
/* If this statement sets an SSA_NAME to an address,
try to propagate the address into the uses of the SSA_NAME. */
if (TREE_CODE (stmt) == MODIFY_EXPR
&& TREE_CODE (TREE_OPERAND (stmt, 1)) == ADDR_EXPR
&& TREE_CODE (TREE_OPERAND (stmt, 0)) == SSA_NAME)
if (TREE_CODE (stmt) == MODIFY_EXPR)
{
if (forward_propagate_addr_expr (stmt))
bsi_remove (&bsi);
tree lhs = TREE_OPERAND (stmt, 0);
tree rhs = TREE_OPERAND (stmt, 1);
if (TREE_CODE (lhs) != SSA_NAME)
{
bsi_next (&bsi);
continue;
}
if (TREE_CODE (rhs) == ADDR_EXPR)
{
if (forward_propagate_addr_expr (stmt))
bsi_remove (&bsi);
else
bsi_next (&bsi);
}
else if ((TREE_CODE (rhs) == BIT_NOT_EXPR
|| TREE_CODE (rhs) == NEGATE_EXPR)
&& TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
{
simplify_not_neg_expr (stmt);
bsi_next (&bsi);
}
else
bsi_next (&bsi);
}