return 0;
}
+#define get_irn_out_n(node) (unsigned)get_irn_link(node)
+#define set_irn_out_n(node, n) set_irn_link(adr, (void *)(n))
+
/**
* walker, collects all Load/Store/Proj nodes
*
walk_env_t *wenv = env;
if (get_irn_op(node) == op_Proj) {
+ ir_node *adr;
+ ir_op *op;
+
pred = get_Proj_pred(node);
+ op = get_irn_op(pred);
- if (get_irn_op(pred) == op_Load || get_irn_op(pred) == op_Store) {
+ if (op == op_Load) {
+ adr = get_Load_ptr(pred);
ldst_info = get_ldst_info(pred, wenv);
wenv->changes |= update_projs(ldst_info, node);
+
+ set_irn_out_n(adr, get_irn_out_n(adr) + 1);
+ }
+ else if (op == op_Store) {
+ adr = get_Store_ptr(pred);
+ ldst_info = get_ldst_info(pred, wenv);
+
+ wenv->changes |= update_projs(ldst_info, node);
+
+ set_irn_out_n(adr, get_irn_out_n(adr) + 1);
}
}
else if (get_irn_op(node) == op_Block) { /* check, if it's an exception block */
ir_node *pred, *mem, *ptr;
int res = 0;
+ /* the address of the load to be optimized */
+ ptr = get_Load_ptr(load);
+
+ /*
+ * Check if we can remove the exception form a Load:
+ * this can be done, if the address is from an Sel(Alloc) and
+ * the Sel type is a subtype of the alloc type.
+ *
+ * This optimizes some often used OO constructs,
+ * like x = new O; x->t;
+ */
+ if (info->projs[pn_Load_X_except]) {
+ if (get_irn_op(ptr) == op_Sel) {
+ ir_node *mem = get_Sel_mem(ptr);
+
+ if (get_irn_op(mem) == op_Alloc) {
+ /* ok, check the types */
+ entity *ent = get_Sel_entity(ptr);
+ type *s_type = get_entity_type(ent);
+ type *a_type = get_Alloc_type(mem);
+
+ if (is_subclass_of(s_type, a_type)) {
+ /* ok, condition met: there can't be an exception because
+ * alloc guarantees that enough memory was allocated */
+
+ exchange(info->projs[pn_Load_X_except], new_Bad());
+ info->projs[pn_Load_X_except] = NULL;
+ }
+ }
+ }
+ else if (get_irn_op(ptr) == op_Alloc) {
+ /* simple case: a direct load after an Alloc. Firm Alloc throw
+ * an exception in case of out-of-memory. So, there is no way for an
+ * exception in this load.
+ * This code is constructed by the "exception lowering" in the Jack compiler.
+ */
+ exchange(info->projs[pn_Load_X_except], new_Bad());
+ info->projs[pn_Load_X_except] = NULL;
+ }
+ }
+
/* do NOT touch volatile loads for now */
if (get_Load_volatility(load) == volatility_is_volatile)
return 0;
return 1;
}
- /* the address of the load to be optimized */
- ptr = get_Load_ptr(load);
-
- /* the mem of the load. Must still be returned after optimization */
+ /* the mem of the Load. Must still be returned after optimization */
mem = get_Load_mem(load);
if ((get_irn_opcode(ptr) == iro_SymConst) && (get_SymConst_kind(ptr) == symconst_addr_ent)) {
}
}
+ /* Check, if the address of this load is used more than once.
+ * If not, this load cannot be removed in any case. */
+ if (get_irn_out_n(ptr) <= 1)
+ return 0;
+
/* follow the memory chain as long as there are only Loads */
for (pred = skip_Proj(mem); ; pred = skip_Proj(get_Load_mem(pred))) {
ldst_info_t *pred_info = get_irn_link(pred);
/*
- * a load immediately after a store -- a read after write.
- * We may remove the Load, if both load & Store does not have an exception handler
+ * a Load immediately after a Store -- a read after write.
+ * We may remove the Load, if both Load & Store does not have an exception handler
* OR they are in the same block. In the latter case the Load cannot
* throw an exception when the previous Store was quiet.
*
* Why we need to check for Store Exc? If the Store cannot be executed (ROM)
* the exception handler might simply jump into the load block :-(
* We could make it a little bit better if we would know that the exception
- * handler of teh Store jumps directly to the end...
+ * handler of the Store jumps directly to the end...
*/
if ((!pred_info->projs[pn_Store_X_except] && !info->projs[pn_Load_X_except]) ||
get_nodes_block(load) == get_nodes_block(pred)) {
else if (get_irn_op(pred) == op_Load && get_Load_ptr(pred) == ptr &&
get_Load_mode(pred) == load_mode) {
/*
- * a load after a load -- a read after read.
+ * a Load after a Load -- a read after read.
* We may remove the second Load, if it does not have an exception handler
* OR they are in the same block. In the later case the Load cannot
* throw an exception when the previous Load was quiet.
*
- * Here, there is no need to check if the previos load has an exception hander because
+ * Here, there is no need to check if the previos Load has an exception hander because
* they would have exact the same exception...
*/
if (! info->projs[pn_Load_X_except] || get_nodes_block(load) == get_nodes_block(pred)) {
}
}
- /* follow only load chains */
+ /* follow only Load chains */
if (get_irn_op(pred) != op_Load)
break;
}
* is possible *(type1 *)p = a; *(type2 *)p = b ...
*/
- block = get_nodes_block(store);
ptr = get_Store_ptr(store);
+
+ /* Check, if the address of this load is used more than once.
+ * If not, this load cannot be removed in any case. */
+ if (get_irn_out_n(ptr) <= 1)
+ return 0;
+
+ block = get_nodes_block(store);
mem = get_Store_mem(store);
value = get_Store_value(store);
-
mode = get_irn_mode(value);
/* follow the memory chain as long as there are only Loads */
if (get_irn_op(pred) == op_Store && get_Store_ptr(pred) == ptr &&
get_nodes_block(pred) == block && get_irn_mode(get_Store_value(pred)) == mode) {
/*
- * a store after a store in the same block -- a write after write.
+ * a Store after a Store in the same block -- a write after write.
* We may remove the first Store, if it does not have an exception handler.
*
* TODO: What, if both have the same exception handler ???
else if (get_irn_op(pred) == op_Load && get_Load_ptr(pred) == ptr &&
value == pred_info->projs[pn_Load_res]) {
/*
- * a store of a value after a load -- a write after read.
+ * a Store of a value after a Load -- a write after read.
* We may remove the second Store, if it does not have an exception handler.
*/
if (! info->projs[pn_Store_X_except]) {
}
}
- /* follow only load chains */
+ /* follow only Load chains */
if (get_irn_op(pred) != op_Load)
break;
}
projects / libfirm / commitdiff