}
-#if 0
-/* Return true if OP is the result of an ASSERT_EXPR that tests the
- same condition as COND. */
-
-static bool
-has_assert_expr (tree op, tree cond)
-{
- tree def_stmt = SSA_NAME_DEF_STMT (op);
- tree assert_expr, other_cond, other_op;
-
- /* If OP was not generated by an ASSERT_EXPR, return false. */
- if (TREE_CODE (def_stmt) != MODIFY_EXPR
- || TREE_CODE (TREE_OPERAND (def_stmt, 1)) != ASSERT_EXPR)
- return false;
-
- assert_expr = TREE_OPERAND (def_stmt, 1);
- other_cond = ASSERT_EXPR_COND (assert_expr);
- other_op = ASSERT_EXPR_VAR (assert_expr);
-
- if (TREE_CODE (cond) == TREE_CODE (other_cond))
- {
- tree t1, t2;
-
- /* If COND is not a comparison predicate, something is wrong. */
- gcc_assert (COMPARISON_CLASS_P (cond));
-
- /* Note that we only need to compare against one of the operands
- of OTHER_COND.
-
- Suppose that we are about to insert the assertion ASSERT_EXPR
- <x_4, x_4 != 0> and the defining statement for x_4 is x_4 =
- ASSERT_EXPR <x_3, x_3 != 0>.
-
- In this case, we don't really want to insert a new
- ASSERT_EXPR for x_4 because that would be redundant. We
- already know that x_4 is not 0. So, when comparing the
- conditionals 'x_3 != 0' and 'x_4 != 0', we don't want to
- compare x_3 and x_4, we just want to compare the predicate's
- code (!=) and the other operand (0). */
- if (TREE_OPERAND (cond, 0) == op)
- t1 = TREE_OPERAND (cond, 1);
- else
- t1 = TREE_OPERAND (cond, 0);
-
- if (TREE_OPERAND (other_cond, 0) == other_op)
- t2 = TREE_OPERAND (other_cond, 1);
- else
- t2 = TREE_OPERAND (other_cond, 0);
-
- return (t1 == t2 || operand_equal_p (t1, t2, 0));
- }
-
- return false;
-}
-
-
-/* Traverse all the statements in block BB looking for used variables.
- Variables used in BB are added to bitmap FOUND. The algorithm
- works in three main parts:
-
- 1- For every statement S in BB, all the variables used by S are
- added to bitmap FOUND.
-
- 2- If statement S uses an operand N in a way that exposes a known
- value range for N, then if N was not already generated by an
- ASSERT_EXPR, create a new ASSERT_EXPR for N. For instance, if N
- is a pointer and the statement dereferences it, we can assume
- that N is not NULL.
-
- 3- COND_EXPRs are a special case of #2. We can derive range
- information from the predicate but need to insert different
- ASSERT_EXPRs for each of the sub-graphs rooted at the
- conditional block. If the last statement of BB is a conditional
- expression of the form 'X op Y', then
-
- a) Remove X and Y from the set FOUND.
-
- b) If the conditional dominates its THEN_CLAUSE sub-graph,
- recurse into it. On return, if X and/or Y are marked in
- FOUND, then an ASSERT_EXPR is added for the corresponding
- variable.
-
- c) Repeat step (b) on the ELSE_CLAUSE.
-
- d) Mark X and Y in FOUND.
-
- 4- If BB does not end in a conditional expression, then we recurse
- into BB's dominator children.
-
- At the end of the recursive traversal, ASSERT_EXPRs will have been
- added to the edges of COND_EXPR blocks that have sub-graphs using
- one or both predicate operands. For instance,
-
- if (a == 9)
- b = a;
- else
- b = c + 1;
-
- In this case, an assertion on the THEN clause is useful to
- determine that 'a' is always 9 on that edge. However, an assertion
- on the ELSE clause would be unnecessary.
-
- On exit from this function, all the names created by the newly
- inserted ASSERT_EXPRs need to be added to the SSA web by rewriting
- the SSA names that they replace.
-
- TODO. Handle SWITCH_EXPR. */
-
-static bool
-maybe_add_assert_expr (basic_block bb)
-{
- block_stmt_iterator si;
- tree last;
- bool added;
-
- /* Step 1. Mark all the SSA names used in BB in bitmap FOUND. */
- added = false;
- last = NULL_TREE;
- for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
- {
- tree stmt, op;
- ssa_op_iter i;
-
- stmt = bsi_stmt (si);
-
- /* Mark all the SSA names used by STMT in bitmap FOUND. If STMT
- is inside the sub-graph of a conditional block, when we
- return from this recursive walk, our parent will use the
- FOUND bitset to determine if one of the operands it was
- looking for was present in the sub-graph. */
- FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
- {
- tree cond;
-
- /* If OP is used only once, namely in this STMT, don't
- bother inserting an ASSERT_EXPR for it. Such an
- ASSERT_EXPR would do nothing but increase compile time.
- Experiments show that with this simple check, we can save
- more than 20% of ASSERT_EXPRs. */
- if (has_single_use (op))
- continue;
-
- SET_BIT (found, SSA_NAME_VERSION (op));
-
- cond = infer_value_range (stmt, op);
- if (!cond)
- continue;
-
- /* Step 2. If OP is used in such a way that we can infer a
- value range for it, create a new ASSERT_EXPR for OP
- (unless OP already has an ASSERT_EXPR). */
- gcc_assert (!is_ctrl_stmt (stmt));
-
- if (has_assert_expr (op, cond))
- continue;
-
- if (!stmt_ends_bb_p (stmt))
- {
- /* If STMT does not end the block, we can insert the new
- assertion right after it. */
- tree t = build_assert_expr_for (cond, op);
- bsi_insert_after (&si, t, BSI_NEW_STMT);
- added = true;
- }
- else
- {
- /* STMT must be the last statement in BB. We can only
- insert new assertions on the non-abnormal edge out of
- BB. Note that since STMT is not control flow, there
- may only be one non-abnormal edge out of BB. */
- edge_iterator ei;
- edge e;
-
- FOR_EACH_EDGE (e, ei, bb->succs)
- if (!(e->flags & EDGE_ABNORMAL))
- {
- tree t = build_assert_expr_for (cond, op);
- bsi_insert_on_edge (e, t);
- added = true;
- break;
- }
- }
- }
-
- /* Remember the last statement of the block. */
- last = stmt;
- }
-
- /* Step 3. If BB's last statement is a conditional expression
- involving integer operands, recurse into each of the sub-graphs
- rooted at BB to determine if we need to add ASSERT_EXPRs.
- Notice that we only care about the first operand of the
- conditional. Adding assertions for both operands may actually
- hinder VRP. FIXME, add example. */
- if (last
- && TREE_CODE (last) == COND_EXPR
- && !fp_predicate (COND_EXPR_COND (last))
- && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
- {
- edge e;
- edge_iterator ei;
- tree op, cond;
- basic_block son;
- ssa_op_iter iter;
-
- cond = COND_EXPR_COND (last);
-
- /* Get just the first use operand. */
- FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
- break;
- gcc_assert (op != NULL);
-
- /* Do not attempt to infer anything in names that flow through
- abnormal edges. */
- if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
- return false;
-
- /* Remove the COND_EXPR operand from the FOUND bitmap.
- Otherwise, when we finish traversing each of the sub-graphs,
- we won't know whether the variables were found in the
- sub-graphs or if they had been found in a block upstream from
- BB. */
- RESET_BIT (found, SSA_NAME_VERSION (op));
-
- /* Look for uses of the operands in each of the sub-graphs
- rooted at BB. We need to check each of the outgoing edges
- separately, so that we know what kind of ASSERT_EXPR to
- insert. */
- FOR_EACH_EDGE (e, ei, bb->succs)
- {
- /* If BB strictly dominates the sub-graph at E->DEST,
- recurse into it. */
- if (e->dest != bb
- && dominated_by_p (CDI_DOMINATORS, e->dest, bb))
- added |= maybe_add_assert_expr (e->dest);
-
- /* Once we traversed the sub-graph, check if any block inside
- used either of the predicate's operands. If so, add the
- appropriate ASSERT_EXPR. */
- if (TEST_BIT (found, SSA_NAME_VERSION (op)))
- {
- /* We found a use of OP in the sub-graph rooted at
- E->DEST. Add an ASSERT_EXPR according to whether
- E goes to THEN_CLAUSE or ELSE_CLAUSE. */
- tree c, t;
-
- if (e->flags & EDGE_TRUE_VALUE)
- c = unshare_expr (cond);
- else if (e->flags & EDGE_FALSE_VALUE)
- c = invert_truthvalue (cond);
- else
- gcc_unreachable ();
-
- t = build_assert_expr_for (c, op);
- bsi_insert_on_edge (e, t);
- added = true;
- }
- }
-
- /* Finally, mark all the COND_EXPR operands as found. */
- SET_BIT (found, SSA_NAME_VERSION (op));
-
- /* Recurse into the dominator children of BB that are not BB's
- immediate successors. Note that we have already visited BB's
- other dominator children above. */
- for (son = first_dom_son (CDI_DOMINATORS, bb);
- son;
- son = next_dom_son (CDI_DOMINATORS, son))
- {
- if (find_edge (bb, son) == NULL)
- added |= maybe_add_assert_expr (son);
- }
- }
- else
- {
- /* Step 4. Recurse into the dominator children of BB. */
- basic_block son;
-
- for (son = first_dom_son (CDI_DOMINATORS, bb);
- son;
- son = next_dom_son (CDI_DOMINATORS, son))
- added |= maybe_add_assert_expr (son);
- }
-
- return added;
-}
-#endif
-
-
void dump_asserts_for (FILE *, tree);
void debug_asserts_for (tree);
void dump_all_asserts (FILE *);
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