== NULL);
}
-/* Return the use stmt for the lhs of STMT following the virtual
- def-use chains. Returns the MODIFY_EXPR stmt which lhs is equal to
- the lhs of STMT or NULL_TREE if no such stmt can be found. */
-static tree
-get_use_of_stmt_lhs (tree stmt,
- use_operand_p * first_use_p,
- use_operand_p * use_p, tree * use_stmt)
+/* Return true if there is a stmt that kills the lhs of STMT and is in the
+ virtual def-use chain of STMT without a use inbetween the kill and STMT.
+ Returns false if no such stmt is found.
+ *FIRST_USE_P is set to the first use of the single virtual def of
+ STMT. *USE_P is set to the vop killed by *USE_STMT. */
+
+static bool
+get_kill_of_stmt_lhs (tree stmt,
+ use_operand_p * first_use_p,
+ use_operand_p * use_p, tree * use_stmt)
{
- tree usevar, lhs;
- def_operand_p def_p;
+ tree lhs;
- if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT)
- return NULL_TREE;
+ gcc_assert (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT);
lhs = GIMPLE_STMT_OPERAND (stmt, 0);
- /* The stmt must have a single VDEF. */
- def_p = SINGLE_SSA_DEF_OPERAND (stmt, SSA_OP_VDEF);
- if (def_p == NULL_DEF_OPERAND_P)
- return NULL_TREE;
-
- if (!has_single_use (DEF_FROM_PTR (def_p)))
- return NULL_TREE;
- /* Get the immediate use of the def. */
- single_imm_use (DEF_FROM_PTR (def_p), use_p, use_stmt);
- gcc_assert (*use_p != NULL_USE_OPERAND_P);
- first_use_p = use_p;
-
- /* If the use is not simple, give up. */
- if (TREE_CODE (*use_stmt) != GIMPLE_MODIFY_STMT
- || get_call_expr_in (*use_stmt))
- return NULL_TREE;
-
+ /* We now walk the chain of single uses of the single VDEFs.
+ We succeeded finding a kill if the lhs of the use stmt is
+ equal to the original lhs. We can keep walking to the next
+ use if there are no possible uses of the original lhs in
+ the stmt. */
do
{
- /* Look at the use stmt and see if it's LHS matches
- stmt's lhs SSA_NAME. */
- def_p = SINGLE_SSA_DEF_OPERAND (*use_stmt, SSA_OP_VDEF);
+ tree use_lhs, use_rhs;
+ def_operand_p def_p;
+
+ /* The stmt must have a single VDEF. */
+ def_p = SINGLE_SSA_DEF_OPERAND (stmt, SSA_OP_VDEF);
if (def_p == NULL_DEF_OPERAND_P)
- return NULL_TREE;
+ return false;
+
+ /* Get the single immediate use of the def. */
+ if (!single_imm_use (DEF_FROM_PTR (def_p), first_use_p, &stmt))
+ return false;
+ first_use_p = use_p;
- usevar = GIMPLE_STMT_OPERAND (*use_stmt, 0);
- if (operand_equal_p (usevar, lhs, 0))
- return *use_stmt;
+ /* If there are possible hidden uses, give up. */
+ if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT)
+ return false;
+ use_rhs = GIMPLE_STMT_OPERAND (stmt, 1);
+ if (TREE_CODE (use_rhs) == CALL_EXPR
+ || (!is_gimple_min_invariant (use_rhs)
+ && TREE_CODE (use_rhs) != SSA_NAME))
+ return false;
- if (!has_single_use (DEF_FROM_PTR (def_p)))
- return NULL_TREE;
- single_imm_use (DEF_FROM_PTR (def_p), use_p, use_stmt);
- gcc_assert (*use_p != NULL_USE_OPERAND_P);
- if (TREE_CODE (*use_stmt) != GIMPLE_MODIFY_STMT
- || get_call_expr_in (*use_stmt))
- return NULL_TREE;
+ /* If the use stmts lhs matches the original lhs we have
+ found the kill, otherwise continue walking. */
+ use_lhs = GIMPLE_STMT_OPERAND (stmt, 0);
+ if (operand_equal_p (use_lhs, lhs, 0))
+ {
+ *use_stmt = stmt;
+ return true;
+ }
}
while (1);
-
- return NULL_TREE;
}
/* A helper of dse_optimize_stmt.
the stores are not to the same memory location then walk the
virtual def-use chain to get the stmt which stores to that same
memory location. */
- if (get_use_of_stmt_lhs (stmt, &first_use_p, &use_p, &use_stmt) ==
- NULL_TREE)
+ if (!get_kill_of_stmt_lhs (stmt, &first_use_p, &use_p, &use_stmt))
{
record_voperand_set (dse_gd->stores, &bd->stores, ann->uid);
return;
vuse_vec_p vv;
tree stmt_lhs;
+ if (LOADED_SYMS (use_stmt))
+ {
+ tree use_base
+ = get_base_address (GIMPLE_STMT_OPERAND (use_stmt, 0));
+ /* If use_stmt is or might be a nop assignment, e.g. for
+ struct { ... } S a, b, *p; ...
+ b = a; b = b;
+ or
+ b = a; b = *p; where p might be &b, then USE_STMT
+ acts as a use as well as definition, so store in STMT
+ is not dead. */
+ if (TREE_CODE (use_base) == VAR_DECL
+ && bitmap_bit_p (LOADED_SYMS (use_stmt),
+ DECL_UID (use_base)))
+ {
+ record_voperand_set (dse_gd->stores, &bd->stores, ann->uid);
+ return;
+ }
+ }
+
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, " Deleted dead store '");
bitmap_ior_into (variables_loaded,
LOADED_SYMS (bsi_stmt (bsi)));
- /* Look for statements writting into the write only variables.
+ /* Look for statements writing into the write only variables.
And try to remove them. */
FOR_EACH_BB (bb)
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