return true;
}
+/* Update *ARG which is defined in STMT so that it contains the
+ computed value if that seems profitable. Return true if the
+ statement is made dead by that rewriting. */
+
+static bool
+jump_function_from_stmt (tree *arg, gimple stmt)
+{
+ enum tree_code code = gimple_assign_rhs_code (stmt);
+ if (code == ADDR_EXPR)
+ {
+ /* For arg = &p->i transform it to p, if possible. */
+ tree rhs1 = gimple_assign_rhs1 (stmt);
+ HOST_WIDE_INT offset;
+ tree tem = get_addr_base_and_unit_offset (TREE_OPERAND (rhs1, 0),
+ &offset);
+ if (tem
+ && TREE_CODE (tem) == MEM_REF
+ && double_int_zero_p
+ (double_int_add (mem_ref_offset (tem),
+ shwi_to_double_int (offset))))
+ {
+ *arg = TREE_OPERAND (tem, 0);
+ return true;
+ }
+ }
+ /* TODO: Much like IPA-CP jump-functions we want to handle constant
+ additions symbolically here, and we'd need to update the comparison
+ code that compares the arg + cst tuples in our caller. For now the
+ code above exactly handles the VEC_BASE pattern from vec.h. */
+ return false;
+}
+
/* The function value_replacement does the main work of doing the value
replacement. Return true if the replacement is done. Otherwise return
false.
edge e0, edge e1, gimple phi,
tree arg0, tree arg1)
{
+ gimple_stmt_iterator gsi;
gimple cond;
edge true_edge, false_edge;
enum tree_code code;
if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1))))
return false;
- if (!empty_block_p (middle_bb))
- return false;
+ /* Allow a single statement in MIDDLE_BB that defines one of the PHI
+ arguments. */
+ gsi = gsi_after_labels (middle_bb);
+ if (!gsi_end_p (gsi))
+ {
+ if (is_gimple_debug (gsi_stmt (gsi)))
+ gsi_next_nondebug (&gsi);
+ if (!gsi_end_p (gsi))
+ {
+ gimple stmt = gsi_stmt (gsi);
+ tree lhs;
+ gsi_next_nondebug (&gsi);
+ if (!gsi_end_p (gsi))
+ return false;
+ if (!is_gimple_assign (stmt))
+ return false;
+ /* Now try to adjust arg0 or arg1 according to the computation
+ in the single statement. */
+ lhs = gimple_assign_lhs (stmt);
+ if (!((lhs == arg0
+ && jump_function_from_stmt (&arg0, stmt))
+ || (lhs == arg1
+ && jump_function_from_stmt (&arg1, stmt))))
+ return false;
+ }
+ }
cond = last_stmt (cond_bb);
code = gimple_cond_code (cond);