X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Fopt%2Fldstopt.c;h=4c29efa0cfb71bb4eb2d3bfdc95830166ffdb9b9;hb=2f7da22ade10e502888999170ef42fcf9a619852;hp=c77552ec3e445f286e3fe031d28c2b0dfbda33ff;hpb=4cc079f84209ec86f1e2a994d2c21e312022b227;p=libfirm diff --git a/ir/opt/ldstopt.c b/ir/opt/ldstopt.c index c77552ec3..4c29efa0c 100644 --- a/ir/opt/ldstopt.c +++ b/ir/opt/ldstopt.c @@ -42,7 +42,7 @@ #include "dbginfo_t.h" #include "iropt_dbg.h" #include "irflag_t.h" -#include "array.h" +#include "array_t.h" #include "irhooks.h" #include "iredges.h" #include "irtools.h" @@ -361,7 +361,7 @@ static compound_graph_path *rec_get_accessed_path(ir_node *ptr, int depth) { if (is_SymConst(ptr)) { /* a SymConst. If the depth is 0, this is an access to a global * entity and we don't need a component path, else we know - * at least it's length. + * at least its length. */ assert(get_SymConst_kind(ptr) == symconst_addr_ent); root = get_SymConst_entity(ptr); @@ -691,7 +691,7 @@ static ir_node *find_compound_ent_value(ir_node *ptr) { static void reduce_adr_usage(ir_node *ptr); /** - * Update a Load that may lost it's usage. + * Update a Load that may have lost its users. */ static void handle_load_update(ir_node *load) { ldst_info_t *info = get_irn_link(load); @@ -704,7 +704,7 @@ static void handle_load_update(ir_node *load) { ir_node *ptr = get_Load_ptr(load); ir_node *mem = get_Load_mem(load); - /* a Load which value is neither used nor exception checked, remove it */ + /* a Load whose value is neither used nor exception checked, remove it */ exchange(info->projs[pn_Load_M], mem); if (info->projs[pn_Load_X_regular]) exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load))); @@ -714,7 +714,7 @@ static void handle_load_update(ir_node *load) { } /* handle_load_update */ /** - * A Use of an address node is vanished. Check if this was a Proj + * A use of an address node has vanished. Check if this was a Proj * node and update the counters. */ static void reduce_adr_usage(ir_node *ptr) { @@ -727,7 +727,7 @@ static void reduce_adr_usage(ir_node *ptr) { ldst_info_t *info = get_irn_link(pred); info->projs[get_Proj_proj(ptr)] = NULL; - /* this node lost it's result proj, handle that */ + /* this node lost its result proj, handle that */ handle_load_update(pred); } } @@ -1125,7 +1125,7 @@ static unsigned optimize_load(ir_node *load) } /* The mem of the Load. Must still be returned after optimization. */ - mem = get_Load_mem(load); + 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 */ @@ -1148,54 +1148,48 @@ static unsigned optimize_load(ir_node *load) value = NULL; /* check if we can determine the entity that will be loaded */ ent = find_constant_entity(ptr); - if (ent != NULL) { - 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 even if we cannot replace the load itself. */ - - /* 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 (info->projs[pn_Load_X_regular]) { - exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load))); - info->projs[pn_Load_X_regular] = NULL; - res |= CF_CHANGED; - } + if (ent != NULL && + 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 even if we cannot replace the load itself. */ + + /* 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 (info->projs[pn_Load_X_regular]) { + exchange(info->projs[pn_Load_X_regular], new_r_Jmp(current_ir_graph, get_nodes_block(load))); + info->projs[pn_Load_X_regular] = NULL; + res |= CF_CHANGED; + } - if (variability_constant == get_entity_variability(ent)) { - if (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 - */ - value = get_atomic_ent_value(ent); - } else { - if (ent->has_initializer) { - /* new style initializer */ - value = find_compound_ent_value(ptr); - } else { - /* old style initializer */ - compound_graph_path *path = get_accessed_path(ptr); - - if (path != NULL) { - assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1)); - - value = get_compound_ent_value_by_path(ent, path); - DB((dbg, LEVEL_1, " Constant access at %F%F resulted in %+F\n", ent, path, value)); - free_compound_graph_path(path); - } - } + if (variability_constant == get_entity_variability(ent)) { + if (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 */ + value = get_atomic_ent_value(ent); + } else if (ent->has_initializer) { + /* new style initializer */ + value = find_compound_ent_value(ptr); + } else { + /* old style initializer */ + compound_graph_path *path = get_accessed_path(ptr); + + if (path != NULL) { + assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1)); + + value = get_compound_ent_value_by_path(ent, path); + DB((dbg, LEVEL_1, " Constant access at %F%F resulted in %+F\n", ent, path, value)); + free_compound_graph_path(path); } - if (value != NULL) - value = can_replace_load_by_const(load, value); } + if (value != NULL) + value = can_replace_load_by_const(load, value); } } } @@ -1250,6 +1244,21 @@ 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 */ +/** + * Check whether small is a part of large (starting at same address). + */ +static int is_partially_same(ir_node *small, ir_node *large) +{ + ir_mode *sm = get_irn_mode(small); + ir_mode *lm = get_irn_mode(large); + + /* FIXME: Check endianness */ + return is_Conv(small) && get_Conv_op(small) == large + && get_mode_size_bytes(sm) < get_mode_size_bytes(lm) + && get_mode_arithmetic(sm) == irma_twos_complement + && get_mode_arithmetic(lm) == irma_twos_complement; +} /* is_partially_same */ + /** * follow the memory chain as long as there are only Loads and alias free Stores. * @@ -1274,24 +1283,55 @@ static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr) { * if the pointers are identical, they refer to the same object. * This is only true in strong typed languages, not is C were the following * is possible *(ir_type1 *)p = a; *(ir_type2 *)p = b ... - * However, if the mode that is written have a bigger or equal size the the old - * one, the old value is completely overwritten and can be killed ... + * However, if the size of the mode that is written is bigger or equal the + * size of the old one, the old value is completely overwritten and can be + * killed ... */ if (is_Store(pred) && get_Store_ptr(pred) == ptr && - get_nodes_MacroBlock(pred) == mblk && - is_completely_overwritten(get_irn_mode(get_Store_value(pred)), mode)) { + get_nodes_MacroBlock(pred) == mblk) { /* * a Store after a Store in the same MacroBlock -- a write after write. - * We may remove the first Store, if it does not have an exception handler. + */ + + /* + * We may remove the first Store, if the old value is completely + * overwritten or the old value is a part of the new value, + * and if it does not have an exception handler. * * TODO: What, if both have the same exception handler ??? */ - if (get_Store_volatility(pred) != volatility_is_volatile && !pred_info->projs[pn_Store_X_except]) { - DBG_OPT_WAW(pred, store); - exchange(pred_info->projs[pn_Store_M], get_Store_mem(pred)); - kill_node(pred); - reduce_adr_usage(ptr); - return DF_CHANGED; + if (get_Store_volatility(pred) != volatility_is_volatile + && !pred_info->projs[pn_Store_X_except]) { + ir_node *predvalue = get_Store_value(pred); + ir_mode *predmode = get_irn_mode(predvalue); + + if(is_completely_overwritten(predmode, mode) + || is_partially_same(predvalue, value)) { + DBG_OPT_WAW(pred, store); + exchange(pred_info->projs[pn_Store_M], get_Store_mem(pred)); + kill_node(pred); + reduce_adr_usage(ptr); + return DF_CHANGED; + } + } + + /* + * We may remove the Store, if the old value already contains + * the new value, and if it does not have an exception handler. + * + * TODO: What, if both have the same exception handler ??? + */ + if (get_Store_volatility(store) != volatility_is_volatile + && !info->projs[pn_Store_X_except]) { + ir_node *predvalue = get_Store_value(pred); + + if(is_partially_same(value, predvalue)) { + DBG_OPT_WAW(pred, store); + exchange(info->projs[pn_Store_M], mem); + kill_node(store); + reduce_adr_usage(ptr); + return DF_CHANGED; + } } } else if (is_Load(pred) && get_Load_ptr(pred) == ptr && value == pred_info->projs[pn_Load_res]) {