* toplev.h (flag_delete_null_pointer_checks): Move from here to...
* flags.h (flag_delete_null_pointer_checks): Here.
* tree-flow.h (cprop_into_successor_phis): Add argument to prototype.
* tree-phinodes.c (resize_phi_node): Initialize PHI_ARG_NONZERO.
(add_phi_arg, remove_phi_arg_num): Similarly.
* tree-ssa-copy.c (cprop_into_successor_phis): Propagate nonzero
property into PHI nodes.
* tree-ssa-dom.c: Remove redundant inclusion of flags.h.
(record_equivalences_from_phis): If all PHI arguments are known to be
nonzero, then the result must be nonzero as well.
(cprop_into_phis): Pass nonzero_vars bitmap to cprop_into_successor_phis (record_equivalences_from_stmt): Check flag_delete_null_pointer_checks
appropriately. Walk the USE-DEF chains and propagate nonzero property
as appropriate.
* tree.h (PHI_ARG_NONZERO): Define.
(phi_arg_d): Add nonzero flag.
From-SVN: r81968
+2004-05-17 Jeff Law <law@redhat.com>
+
+ * toplev.h (flag_delete_null_pointer_checks): Move from here to...
+ * flags.h (flag_delete_null_pointer_checks): Here.
+ * tree-flow.h (cprop_into_successor_phis): Add argument to prototype.
+ * tree-phinodes.c (resize_phi_node): Initialize PHI_ARG_NONZERO.
+ (add_phi_arg, remove_phi_arg_num): Similarly.
+ * tree-ssa-copy.c (cprop_into_successor_phis): Propagate nonzero
+ property into PHI nodes.
+ * tree-ssa-dom.c: Remove redundant inclusion of flags.h.
+ (record_equivalences_from_phis): If all PHI arguments are known to be
+ nonzero, then the result must be nonzero as well.
+ (cprop_into_phis): Pass nonzero_vars bitmap to cprop_into_successor_phis (record_equivalences_from_stmt): Check flag_delete_null_pointer_checks
+ appropriately. Walk the USE-DEF chains and propagate nonzero property
+ as appropriate.
+ * tree.h (PHI_ARG_NONZERO): Define.
+ (phi_arg_d): Add nonzero flag.
+
2004-05-17 Zack Weinberg <zack@codesourcery.com>
* f: Entire directory removed
perform miscellaneous relatively-expensive optimizations. */
extern int flag_expensive_optimizations;
+/* Nonzero means to use global dataflow analysis to eliminate
+ useless null pointer tests. */
+extern int flag_delete_null_pointer_checks;
+
/* Nonzero means don't put addresses of constant functions in registers.
Used for compiling the Unix kernel, where strange substitutions are
done on the assembly output. */
extern int flag_crossjumping;
extern int flag_if_conversion;
extern int flag_if_conversion2;
-extern int flag_delete_null_pointer_checks;
extern int flag_keep_static_consts;
extern int flag_peel_loops;
extern int flag_rerun_cse_after_loop;
extern void propagate_value (tree *, tree);
extern void replace_exp (tree *, tree);
extern bool cprop_into_stmt (tree, varray_type);
-extern void cprop_into_successor_phis (basic_block, varray_type);
+extern void cprop_into_successor_phis (basic_block, varray_type, bitmap);
/* In tree-flow-inline.h */
static inline int phi_arg_from_edge (tree, edge);
{
PHI_ARG_DEF (new_phi, i) = NULL_TREE;
PHI_ARG_EDGE (new_phi, i) = NULL;
+ PHI_ARG_NONZERO (new_phi, i) = false;
}
*phi = new_phi;
PHI_ARG_DEF (*phi, i) = def;
PHI_ARG_EDGE (*phi, i) = e;
+ PHI_ARG_NONZERO (*phi, i) = false;
PHI_NUM_ARGS (*phi)++;
}
{
PHI_ARG_DEF (phi, i) = PHI_ARG_DEF (phi, num_elem - 1);
PHI_ARG_EDGE (phi, i) = PHI_ARG_EDGE (phi, num_elem - 1);
+ PHI_ARG_NONZERO (phi, i) = PHI_ARG_NONZERO (phi, num_elem - 1);
}
/* Shrink the vector and return. */
PHI_ARG_DEF (phi, num_elem - 1) = NULL_TREE;
PHI_ARG_EDGE (phi, num_elem - 1) = NULL;
+ PHI_ARG_NONZERO (phi, num_elem - 1) = false;
PHI_NUM_ARGS (phi)--;
/* If we removed the last PHI argument, then go ahead and
#include "domwalk.h"
#include "real.h"
#include "tree-pass.h"
-#include "flags.h"
#include "langhooks.h"
/* This file implements optimizations on the dominator tree. */
Ignoring any alternatives which are the same as the result, if
all the alternatives are equal, then the PHI node creates an
- equivalence. */
+ equivalence.
+
+ Additionally, if all the PHI alternatives are known to have a nonzero
+ value, then the result of this PHI is known to have a nonzero value,
+ even if we do not know its exact value. */
+
static void
record_equivalences_from_phis (struct dom_walk_data *walk_data, basic_block bb)
{
&& may_propagate_copy (lhs, rhs))
set_value_for (lhs, rhs, const_and_copies);
+ /* Now see if we know anything about the nonzero property for the
+ result of this PHI. */
+ for (i = 0; i < PHI_NUM_ARGS (phi); i++)
+ {
+ if (!PHI_ARG_NONZERO (phi, i))
+ break;
+ }
+
+ if (i == PHI_NUM_ARGS (phi))
+ bitmap_set_bit (nonzero_vars, SSA_NAME_VERSION (PHI_RESULT (phi)));
+
register_new_def (lhs, &bd->block_defs);
}
}
cprop_into_phis (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
basic_block bb)
{
- cprop_into_successor_phis (bb, const_and_copies);
+ cprop_into_successor_phis (bb, const_and_copies, nonzero_vars);
}
/* Search for redundant computations in STMT. If any are found, then
/* Look at both sides for pointer dereferences. If we find one, then
the pointer must be nonnull and we can enter that equivalence into
the hash tables. */
- for (i = 0; i < 2; i++)
- {
- tree t = TREE_OPERAND (stmt, i);
-
- /* Strip away any COMPONENT_REFs. */
- while (TREE_CODE (t) == COMPONENT_REF)
- t = TREE_OPERAND (t, 0);
-
- /* Now see if this is a pointer dereference. */
- if (TREE_CODE (t) == INDIRECT_REF)
- {
- tree op = TREE_OPERAND (t, 0);
-
- /* If the pointer is a SSA variable, then enter new
- equivalences into the hash table. */
- if (TREE_CODE (op) == SSA_NAME)
- record_var_is_nonzero (op, block_nonzero_vars_p);
- }
- }
+ if (flag_delete_null_pointer_checks)
+ for (i = 0; i < 2; i++)
+ {
+ tree t = TREE_OPERAND (stmt, i);
+
+ /* Strip away any COMPONENT_REFs. */
+ while (TREE_CODE (t) == COMPONENT_REF)
+ t = TREE_OPERAND (t, 0);
+
+ /* Now see if this is a pointer dereference. */
+ if (TREE_CODE (t) == INDIRECT_REF)
+ {
+ tree op = TREE_OPERAND (t, 0);
+
+ /* If the pointer is a SSA variable, then enter new
+ equivalences into the hash table. */
+ while (TREE_CODE (op) == SSA_NAME)
+ {
+ tree def = SSA_NAME_DEF_STMT (op);
+
+ record_var_is_nonzero (op, block_nonzero_vars_p);
+
+ /* And walk up the USE-DEF chains noting other SSA_NAMEs
+ which are known to have a nonzero value. */
+ if (def
+ && TREE_CODE (def) == MODIFY_EXPR
+ && TREE_CODE (TREE_OPERAND (def, 1)) == NOP_EXPR)
+ op = TREE_OPERAND (TREE_OPERAND (def, 1), 0);
+ else
+ break;
+ }
+ }
+ }
/* A memory store, even an aliased store, creates a useful
equivalence. By exchanging the LHS and RHS, creating suitable
#define PHI_ARG_ELT(NODE, I) PHI_NODE_ELT_CHECK (NODE, I)
#define PHI_ARG_EDGE(NODE, I) PHI_NODE_ELT_CHECK (NODE, I).e
#define PHI_ARG_DEF(NODE, I) PHI_NODE_ELT_CHECK (NODE, I).def
+#define PHI_ARG_NONZERO(NODE, I) PHI_NODE_ELT_CHECK (NODE, I).nonzero
struct edge_def;
{
tree def;
struct edge_def * GTY((skip (""))) e;
+ bool nonzero;
};
struct tree_phi_node GTY(())
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