- ldst_info_t *info = get_irn_link(load);
- ir_mode *load_mode = get_Load_mode(load);
- ir_node *mem, *ptr, *new_node;
- entity *ent;
- unsigned res = 0;
-
- /* do NOT touch volatile loads for now */
- if (get_Load_volatility(load) == volatility_is_volatile)
- return 0;
-
- /* the address of the load to be optimized */
- ptr = get_Load_ptr(load);
-
- /*
- * Check if we can remove the exception from a Load:
- * This can be done, if the address is from an Sel(Alloc) and
- * the Sel type is a subtype of the allocated type.
- *
- * This optimizes some often used OO constructs,
- * like x = new O; x->t;
- */
- if (info->projs[pn_Load_X_except]) {
- if (is_Sel(ptr)) {
- ir_node *mem = get_Sel_mem(ptr);
-
- if (get_irn_op(skip_Proj(mem)) == op_Alloc) {
- /* ok, check the types */
- entity *ent = get_Sel_entity(ptr);
- ir_type *s_type = get_entity_type(ent);
- ir_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;
- res |= CF_CHANGED;
- }
- }
- }
- else if ((get_irn_op(skip_Proj(ptr)) == op_Alloc) ||
- ((get_irn_op(ptr) == op_Cast) && (get_irn_op(skip_Proj(get_Cast_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;
- res |= CF_CHANGED;
- }
- }
-
- /* the mem of the Load. Must still be returned after optimization */
- mem = get_Load_mem(load);
-
- if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
- /* a Load which value is neither used nor exception checked, remove it */
- exchange(info->projs[pn_Load_M], mem);
-
- exchange(load, new_Bad());
- reduce_adr_usage(ptr);
- return res | DF_CHANGED;
- }
-
- /* Load from a constant polymorphic field, where we can resolve
- polymorphism. */
- new_node = transform_node_Load(load);
- if (new_node != load) {
- if (info->projs[pn_Load_M]) {
- exchange(info->projs[pn_Load_M], mem);
- info->projs[pn_Load_M] = NULL;
- }
- if (info->projs[pn_Load_X_except]) {
- exchange(info->projs[pn_Load_X_except], new_Bad());
- info->projs[pn_Load_X_except] = NULL;
- }
- if (info->projs[pn_Load_res])
- exchange(info->projs[pn_Load_res], new_node);
-
- exchange(load, new_Bad());
- reduce_adr_usage(ptr);
- return res | DF_CHANGED;
- }
-
- /* check if we can determine the entity that will be loaded */
- ent = find_constant_entity(ptr);
- if (ent) {
- if ((allocation_static == get_entity_allocation(ent)) &&
- (visibility_external_allocated != get_entity_visibility(ent))) {
- /* a static allocation that is not external: there should be NO exception
- * when loading. */
-
- /* no exception, clear the info field as it might be checked later again */
- if (info->projs[pn_Load_X_except]) {
- exchange(info->projs[pn_Load_X_except], new_Bad());
- info->projs[pn_Load_X_except] = NULL;
- res |= CF_CHANGED;
- }
-
- if (variability_constant == get_entity_variability(ent)
- && is_atomic_entity(ent)) {
- /* Might not be atomic after
- lowering of Sels. In this
- case we could also load, but
- it's more complicated. */
- /* more simpler case: we load the content of a constant value:
- * replace it by the constant itself
- */
-
- /* no memory */
- if (info->projs[pn_Load_M]) {
- exchange(info->projs[pn_Load_M], mem);
- res |= DF_CHANGED;
- }
- /* no result :-) */
- if (info->projs[pn_Load_res]) {
- if (is_atomic_entity(ent)) {
- ir_node *c = copy_const_value(get_irn_dbg_info(load), get_atomic_ent_value(ent));
-
- DBG_OPT_RC(load, c);
- exchange(info->projs[pn_Load_res], c);
- res |= DF_CHANGED;
- }
- }
- exchange(load, new_Bad());
- reduce_adr_usage(ptr);
- return res;
- }
- else if (variability_constant == get_entity_variability(ent)) {
- compound_graph_path *path = get_accessed_path(ptr);
-
- if (path) {
- ir_node *c;
-
- assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1));
- /*
- {
- int j;
- for (j = 0; j < get_compound_graph_path_length(path); ++j) {
- entity *node = get_compound_graph_path_node(path, j);
- fprintf(stdout, ".%s", get_entity_name(node));
- if (is_Array_type(get_entity_owner(node)))
- fprintf(stdout, "[%d]", get_compound_graph_path_array_index(path, j));
- }
- printf("\n");
- }
- */
-
- c = get_compound_ent_value_by_path(ent, path);
- free_compound_graph_path(path);
-
- /* printf(" cons: "); DDMN(c); */
-
- if (info->projs[pn_Load_M]) {
- exchange(info->projs[pn_Load_M], mem);
- res |= DF_CHANGED;
- }
- if (info->projs[pn_Load_res]) {
- exchange(info->projs[pn_Load_res], copy_const_value(get_irn_dbg_info(load), c));
- res |= DF_CHANGED;
- }
- exchange(load, new_Bad());
- reduce_adr_usage(ptr);
- return res;
- }
- else {
- /* We can not determine a correct access path. E.g., in jack, we load
- a byte from an object to generate an exception. Happens in test program
- Reflectiontest.
- printf(">>>>>>>>>>>>> Found access to constant entity %s in function %s\n", get_entity_name(ent),
- get_entity_name(get_irg_entity(current_ir_graph)));
- printf(" load: "); DDMN(load);
- printf(" ptr: "); DDMN(ptr);
- */
- }
- }
- }
- }
-
- /* 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_n_uses(ptr) <= 1)
- return res;
-
- /*
- * follow the memory chain as long as there are only Loads
- * and try to replace current Load or Store by a previous one.
- * Note that in unreachable loops it might happen that we reach
- * load again, as well as we can fall into a cycle.
- * We break such cycles using a special visited flag.
- */
- INC_MASTER();
- res = follow_Load_chain(load, skip_Proj(mem));
- return res;
-}
+ ldst_info_t *info = get_irn_link(load);
+ ir_node *mem, *ptr, *new_node;
+ ir_entity *ent;
+ unsigned res = 0;
+
+ /* do NOT touch volatile loads for now */
+ if (get_Load_volatility(load) == volatility_is_volatile)
+ return 0;
+
+ /* the address of the load to be optimized */
+ ptr = get_Load_ptr(load);
+
+ /*
+ * Check if we can remove the exception from a Load:
+ * This can be done, if the address is from an Sel(Alloc) and
+ * the Sel type is a subtype of the allocated type.
+ *
+ * This optimizes some often used OO constructs,
+ * like x = new O; x->t;
+ */
+ if (info->projs[pn_Load_X_except]) {
+ if (is_Sel(ptr)) {
+ ir_node *mem = get_Sel_mem(ptr);
+
+ /* FIXME: works with the current FE, but better use the base */
+ if (get_irn_op(skip_Proj(mem)) == op_Alloc) {
+ /* ok, check the types */
+ ir_entity *ent = get_Sel_entity(ptr);
+ ir_type *s_type = get_entity_type(ent);
+ ir_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;
+ res |= CF_CHANGED;
+ }
+ }
+ } else if ((get_irn_op(skip_Proj(ptr)) == op_Alloc) ||
+ ((get_irn_op(ptr) == op_Cast) && (get_irn_op(skip_Proj(get_Cast_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;
+ res |= CF_CHANGED;
+ }
+ }
+
+ /* The mem of the Load. Must still be returned after optimization. */
+ mem = get_Load_mem(load);
+
+ if (! info->projs[pn_Load_res] && ! info->projs[pn_Load_X_except]) {
+ /* a Load which value is neither used nor exception checked, remove it */
+ exchange(info->projs[pn_Load_M], mem);
+
+ exchange(load, new_Bad());
+ reduce_adr_usage(ptr);
+ return res | DF_CHANGED;
+ }
+
+ /* Load from a constant polymorphic field, where we can resolve
+ polymorphism. */
+ new_node = transform_node_Load(load);
+ if (new_node != load) {
+ if (info->projs[pn_Load_M]) {
+ exchange(info->projs[pn_Load_M], mem);
+ info->projs[pn_Load_M] = NULL;
+ }
+ if (info->projs[pn_Load_X_except]) {
+ exchange(info->projs[pn_Load_X_except], new_Bad());
+ info->projs[pn_Load_X_except] = NULL;
+ }
+ if (info->projs[pn_Load_res])
+ exchange(info->projs[pn_Load_res], new_node);
+
+ exchange(load, new_Bad());
+ reduce_adr_usage(ptr);
+ return res | DF_CHANGED;
+ }
+
+ /* check if we can determine the entity that will be loaded */
+ ent = find_constant_entity(ptr);
+ if (ent) {
+ if ((allocation_static == get_entity_allocation(ent)) &&
+ (visibility_external_allocated != get_entity_visibility(ent))) {
+ /* a static allocation that is not external: there should be NO exception
+ * when loading. */
+
+ /* no exception, clear the info field as it might be checked later again */
+ if (info->projs[pn_Load_X_except]) {
+ exchange(info->projs[pn_Load_X_except], new_Bad());
+ info->projs[pn_Load_X_except] = NULL;
+ res |= CF_CHANGED;
+ }
+
+ if (variability_constant == get_entity_variability(ent)
+ && is_atomic_entity(ent)) {
+ /* Might not be atomic after
+ lowering of Sels. In this
+ case we could also load, but
+ it's more complicated. */
+ /* more simpler case: we load the content of a constant value:
+ * replace it by the constant itself
+ */
+
+ /* no memory */
+ if (info->projs[pn_Load_M]) {
+ exchange(info->projs[pn_Load_M], mem);
+ res |= DF_CHANGED;
+ }
+ /* no result :-) */
+ if (info->projs[pn_Load_res]) {
+ if (is_atomic_entity(ent)) {
+ ir_node *c = copy_const_value(get_irn_dbg_info(load), get_atomic_ent_value(ent));
+
+ DBG_OPT_RC(load, c);
+ exchange(info->projs[pn_Load_res], c);
+ res |= DF_CHANGED;
+ }
+ }
+ exchange(load, new_Bad());
+ reduce_adr_usage(ptr);
+ return res;
+ } else if (variability_constant == get_entity_variability(ent)) {
+ compound_graph_path *path = get_accessed_path(ptr);
+
+ if (path) {
+ ir_node *c;
+
+ assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1));
+ /*
+ {
+ int j;
+ for (j = 0; j < get_compound_graph_path_length(path); ++j) {
+ ir_entity *node = get_compound_graph_path_node(path, j);
+ fprintf(stdout, ".%s", get_entity_name(node));
+ if (is_Array_type(get_entity_owner(node)))
+ fprintf(stdout, "[%d]", get_compound_graph_path_array_index(path, j));
+ }
+ printf("\n");
+ }
+ */
+
+ c = get_compound_ent_value_by_path(ent, path);
+ free_compound_graph_path(path);
+
+ /* printf(" cons: "); DDMN(c); */
+
+ if (info->projs[pn_Load_M]) {
+ exchange(info->projs[pn_Load_M], mem);
+ res |= DF_CHANGED;
+ }
+ if (info->projs[pn_Load_res]) {
+ exchange(info->projs[pn_Load_res], copy_const_value(get_irn_dbg_info(load), c));
+ res |= DF_CHANGED;
+ }
+ exchange(load, new_Bad());
+ reduce_adr_usage(ptr);
+ return res;
+ } else {
+ /* We can not determine a correct access path. E.g., in jack, we load
+ a byte from an object to generate an exception. Happens in test program
+ Reflectiontest.
+ printf(">>>>>>>>>>>>> Found access to constant entity %s in function %s\n", get_entity_name(ent),
+ get_entity_name(get_irg_entity(current_ir_graph)));
+ printf(" load: "); DDMN(load);
+ printf(" ptr: "); DDMN(ptr);
+ */
+ }
+ }
+ }
+ }
+
+ /* 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_n_uses(ptr) <= 1)
+ return res;
+
+ /*
+ * follow the memory chain as long as there are only Loads
+ * and try to replace current Load or Store by a previous one.
+ * Note that in unreachable loops it might happen that we reach
+ * load again, as well as we can fall into a cycle.
+ * We break such cycles using a special visited flag.
+ */
+ INC_MASTER();
+ res = follow_Mem_chain(load, skip_Proj(mem));
+ return res;
+} /* optimize_load */
+
+/**
+ * Check whether a value of mode new_mode would completely overwrite a value
+ * of mode old_mode in memory.
+ */
+static int is_completely_overwritten(ir_mode *old_mode, ir_mode *new_mode)
+{
+ return get_mode_size_bits(new_mode) >= get_mode_size_bits(old_mode);
+} /* is_completely_overwritten */