X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;ds=sidebyside;f=ir%2Fopt%2Fldstopt.c;h=ac883ed29cce5d41b8275843f1d378e2a49a44de;hb=b4a3d8471ab4a2ad12041f4ef1cb2473d9b5fe4c;hp=f5e2cb42834001974ee47d44f0fdb40a6085790b;hpb=e40b97bd28e9d4316aecceb642337847d303d4de;p=libfirm

diff --git a/ir/opt/ldstopt.c b/ir/opt/ldstopt.c
index f5e2cb428..ac883ed29 100644
--- a/ir/opt/ldstopt.c
+++ b/ir/opt/ldstopt.c
@@ -257,10 +257,7 @@ static ir_entity *find_constant_entity(ir_node *ptr)
 {
 	for (;;) {
 		if (is_SymConst(ptr) && get_SymConst_kind(ptr) == symconst_addr_ent) {
-			ir_entity *ent = get_SymConst_entity(ptr);
-			if (variability_constant == get_entity_variability(ent))
-				return ent;
-			return NULL;
+			return get_SymConst_entity(ptr);
 		} else if (is_Sel(ptr)) {
 			ir_entity *ent = get_Sel_entity(ptr);
 			ir_type   *tp  = get_entity_owner(ent);
@@ -364,7 +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);
@@ -386,11 +383,12 @@ static compound_graph_path *rec_get_accessed_path(ir_node *ptr, int depth) {
 			set_compound_graph_path_array_index(res, pos, get_Sel_array_index_long(ptr, 0));
 		}
 	} else if (is_Add(ptr)) {
-		ir_node *l = get_Add_left(ptr);
-		ir_node *r = get_Add_right(ptr);
-		ir_mode *mode;
+		ir_node *l    = get_Add_left(ptr);
+		ir_node *r    = get_Add_right(ptr);
+		ir_mode *mode = get_irn_mode(ptr);
+		tarval  *tmp;
 
-		if (is_Const(r)) {
+		if (is_Const(r) && get_irn_mode(l) == mode) {
 			ptr = l;
 			tv  = get_Const_tarval(r);
 		} else {
@@ -399,6 +397,7 @@ static compound_graph_path *rec_get_accessed_path(ir_node *ptr, int depth) {
 		}
 ptr_arith:
 		mode = get_tarval_mode(tv);
+		tmp  = tv;
 
 		/* ptr must be a Sel or a SymConst, this was checked in find_constant_entity() */
 		if (is_Sel(ptr)) {
@@ -410,7 +409,6 @@ ptr_arith:
 		for (ent = field;;) {
 			unsigned size;
 			tarval   *sz, *tv_index, *tlower, *tupper;
-			long     index;
 			ir_node  *bound;
 
 			tp = get_entity_type(ent);
@@ -420,10 +418,10 @@ ptr_arith:
 			size = get_type_size_bytes(get_entity_type(ent));
 			sz   = new_tarval_from_long(size, mode);
 
-			tv_index = tarval_div(tv, sz);
-			tv       = tarval_mod(tv, sz);
+			tv_index = tarval_div(tmp, sz);
+			tmp      = tarval_mod(tmp, sz);
 
-			if (tv_index == tarval_bad || tv == tarval_bad)
+			if (tv_index == tarval_bad || tmp == tarval_bad)
 				return NULL;
 
 			assert(get_array_n_dimensions(tp) == 1 && "multiarrays not implemented");
@@ -441,10 +439,9 @@ ptr_arith:
 				return NULL;
 
 			/* ok, bounds check finished */
-			index = get_tarval_long(tv_index);
 			++idx;
 		}
-		if (! tarval_is_null(tv)) {
+		if (! tarval_is_null(tmp)) {
 			/* access to some struct/union member */
 			return NULL;
 		}
@@ -502,7 +499,8 @@ ptr_arith:
  * valid, if the graph is in phase_high and _no_ address computation is used.
  */
 static compound_graph_path *get_accessed_path(ir_node *ptr) {
-	return rec_get_accessed_path(ptr, 0);
+	compound_graph_path *gr = rec_get_accessed_path(ptr, 0);
+	return gr;
 }  /* get_accessed_path */
 
 typedef struct path_entry {
@@ -540,7 +538,7 @@ static ir_node *rec_find_compound_ent_value(ir_node *ptr, path_entry *next) {
 					continue;
 				}
 			}
-			if (p->index >= n)
+			if (p->index >= (int) n)
 				return NULL;
 			initializer = get_initializer_compound_value(initializer, p->index);
 
@@ -693,7 +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);
@@ -706,7 +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)));
@@ -716,7 +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) {
@@ -729,7 +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);
 			}
 		}
@@ -774,6 +772,141 @@ static unsigned is_Call_pure(ir_node *call) {
 	return (prop & (mtp_property_const|mtp_property_pure)) != 0;
 }  /* is_Call_pure */
 
+static ir_node *get_base_and_offset(ir_node *ptr, long *pOffset)
+{
+	ir_mode *mode  = get_irn_mode(ptr);
+	long    offset = 0;
+
+	/* TODO: long might not be enough, we should probably use some tarval thingy... */
+	for (;;) {
+		if (is_Add(ptr)) {
+			ir_node *l = get_Add_left(ptr);
+			ir_node *r = get_Add_right(ptr);
+
+			if (get_irn_mode(l) != mode || !is_Const(r))
+				break;
+
+			offset += get_tarval_long(get_Const_tarval(r));
+			ptr     = l;
+		} else if (is_Sub(ptr)) {
+			ir_node *l = get_Sub_left(ptr);
+			ir_node *r = get_Sub_right(ptr);
+
+			if (get_irn_mode(l) != mode || !is_Const(r))
+				break;
+
+			offset -= get_tarval_long(get_Const_tarval(r));
+			ptr     = l;
+		} else if (is_Sel(ptr)) {
+			ir_entity *ent = get_Sel_entity(ptr);
+			ir_type   *tp  = get_entity_owner(ent);
+
+			if (is_Array_type(tp)) {
+				int     size;
+				ir_node *index;
+
+				/* only one dimensional arrays yet */
+				if (get_Sel_n_indexs(ptr) != 1)
+					break;
+				index = get_Sel_index(ptr, 0);
+				if (! is_Const(index))
+					break;
+
+				tp = get_entity_type(ent);
+				if (get_type_state(tp) != layout_fixed)
+					break;
+
+				size    = get_type_size_bytes(tp);
+				offset += size * get_tarval_long(get_Const_tarval(index));
+			} else {
+				if (get_type_state(tp) != layout_fixed)
+					break;
+				offset += get_entity_offset(ent);
+			}
+			ptr = get_Sel_ptr(ptr);
+		} else
+			break;
+	}
+
+	*pOffset = offset;
+	return ptr;
+}
+
+static int try_load_after_store(ir_node *load,
+		ir_node *load_base_ptr, long load_offset, ir_node *store)
+{
+	ldst_info_t *info;
+	ir_node *store_ptr      = get_Store_ptr(store);
+	long     store_offset;
+	ir_node *store_base_ptr = get_base_and_offset(store_ptr, &store_offset);
+	ir_node *store_value;
+	ir_mode *store_mode;
+	ir_node *load_ptr;
+	ir_mode *load_mode;
+	long     load_mode_len;
+	long     store_mode_len;
+	long     delta;
+	int      res;
+
+	if (load_base_ptr != store_base_ptr)
+		return 0;
+
+	load_mode      = get_Load_mode(load);
+	load_mode_len  = get_mode_size_bytes(load_mode);
+	store_mode     = get_irn_mode(get_Store_value(store));
+	store_mode_len = get_mode_size_bytes(store_mode);
+	delta          = load_offset - store_offset;
+	if (delta < 0 || delta + load_mode_len > store_mode_len)
+		return 0;
+
+	if (get_mode_arithmetic(store_mode) != irma_twos_complement ||
+	    get_mode_arithmetic(load_mode)  != irma_twos_complement)
+		return 0;
+
+	store_value = get_Store_value(store);
+
+	/* produce a shift to adjust offset delta */
+	if (delta > 0) {
+		ir_node *cnst;
+
+		/* FIXME: only true for little endian */
+		cnst        = new_Const_long(mode_Iu, delta * 8);
+		store_value = new_r_Shr(current_ir_graph, get_nodes_block(load),
+		                        store_value, cnst, store_mode);
+	}
+
+	/* add an convert if needed */
+	if (store_mode != load_mode) {
+		store_value = new_r_Conv(current_ir_graph, get_nodes_block(load),
+		                         store_value, load_mode);
+	}
+
+	DBG_OPT_RAW(load, store_value);
+
+	info = get_irn_link(load);
+	if (info->projs[pn_Load_M])
+		exchange(info->projs[pn_Load_M], get_Load_mem(load));
+
+	res = 0;
+	/* no exception */
+	if (info->projs[pn_Load_X_except]) {
+		exchange( info->projs[pn_Load_X_except], new_Bad());
+		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)));
+		res |= CF_CHANGED;
+	}
+
+	if (info->projs[pn_Load_res])
+		exchange(info->projs[pn_Load_res], store_value);
+
+	load_ptr = get_Load_ptr(load);
+	kill_node(load);
+	reduce_adr_usage(load_ptr);
+	return res | DF_CHANGED;
+}
+
 /**
  * Follow the memory chain as long as there are only Loads,
  * alias free Stores, and constant Calls and try to replace the
@@ -785,67 +918,39 @@ static unsigned is_Call_pure(ir_node *call) {
  * INC_MASTER() must be called before dive into
  */
 static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
-	unsigned res = 0;
+	unsigned    res = 0;
 	ldst_info_t *info = get_irn_link(load);
-	ir_node *pred;
-	ir_node *ptr       = get_Load_ptr(load);
-	ir_node *mem       = get_Load_mem(load);
-	ir_mode *load_mode = get_Load_mode(load);
+	ir_node     *pred;
+	ir_node     *ptr       = get_Load_ptr(load);
+	ir_node     *mem       = get_Load_mem(load);
+	ir_mode     *load_mode = get_Load_mode(load);
 
 	for (pred = curr; load != pred; ) {
 		ldst_info_t *pred_info = get_irn_link(pred);
 
 		/*
-		 * BEWARE: one might think that checking the modes is useless, because
-		 * if the pointers are identical, they refer to the same object.
-		 * This is only true in strong typed languages, not in C were the following
-		 * is possible a = *(ir_type1 *)p; b = *(ir_type2 *)p ...
+		 * 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 MacroBlock. In the latter
+		 * case the Load cannot throw an exception when the previous Store was
+		 * quiet.
+		 *
+		 * Why we need to check for Store Exception? If the Store cannot
+		 * be executed (ROM) the exception handler might simply jump into
+		 * the load MacroBlock :-(
+		 * We could make it a little bit better if we would know that the
+		 * exception handler of the Store jumps directly to the end...
 		 */
-		if (is_Store(pred) && get_Store_ptr(pred) == ptr &&
-		    can_use_stored_value(get_irn_mode(get_Store_value(pred)), load_mode)) {
-			/*
-			 * 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 MacroBlock. In the latter case the Load cannot
-			 * throw an exception when the previous Store was quiet.
-			 *
-			 * Why we need to check for Store Exception? If the Store cannot
-			 * be executed (ROM) the exception handler might simply jump into
-			 * the load MacroBlock :-(
-			 * We could make it a little bit better if we would know that the exception
-			 * handler of the Store jumps directly to the end...
-			 */
-			if ((pred_info->projs[pn_Store_X_except] == NULL && info->projs[pn_Load_X_except] == NULL) ||
-			    get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)) {
-				ir_node *value = get_Store_value(pred);
-
-				DBG_OPT_RAW(load, value);
-
-				/* add an convert if needed */
-				if (get_irn_mode(get_Store_value(pred)) != load_mode) {
-					value = new_r_Conv(current_ir_graph, get_nodes_block(load), value, load_mode);
-				}
-
-				if (info->projs[pn_Load_M])
-					exchange(info->projs[pn_Load_M], mem);
-
-				/* no exception */
-				if (info->projs[pn_Load_X_except]) {
-					exchange( info->projs[pn_Load_X_except], new_Bad());
-					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)));
-					res |= CF_CHANGED;
-				}
-
-				if (info->projs[pn_Load_res])
-					exchange(info->projs[pn_Load_res], value);
-
-				kill_node(load);
-				reduce_adr_usage(ptr);
-				return res | DF_CHANGED;
-			}
+		if (is_Store(pred) && ((pred_info->projs[pn_Store_X_except] == NULL
+				&& info->projs[pn_Load_X_except] == NULL)
+				|| get_nodes_MacroBlock(load) == get_nodes_MacroBlock(pred)))
+		{
+			long    load_offset;
+			ir_node *base_ptr = get_base_and_offset(ptr, &load_offset);
+			int     changes   = try_load_after_store(load, base_ptr, load_offset, pred);
+
+			if (changes != 0)
+				return res | changes;
 		} else if (is_Load(pred) && get_Load_ptr(pred) == ptr &&
 		           can_use_stored_value(get_Load_mode(pred), load_mode)) {
 			/*
@@ -944,6 +1049,33 @@ static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
 	return res;
 }  /* follow_Mem_chain */
 
+/*
+ * Check if we can replace the load by a given const from
+ * the const code irg.
+ */
+ir_node *can_replace_load_by_const(const ir_node *load, ir_node *c) {
+	ir_mode *c_mode = get_irn_mode(c);
+	ir_mode *l_mode = get_Load_mode(load);
+	ir_node *res    = NULL;
+
+	if (c_mode != l_mode) {
+		/* check, if the mode matches OR can be easily converted info */
+		if (is_reinterpret_cast(c_mode, l_mode)) {
+			/* we can safely cast */
+			dbg_info *dbg   = get_irn_dbg_info(load);
+			ir_node  *block = get_nodes_block(load);
+
+			/* copy the value from the const code irg and cast it */
+			res = copy_const_value(dbg, c);
+			res = new_rd_Conv(dbg, current_ir_graph, block, res, l_mode);
+		}
+	} else {
+		/* copy the value from the const code irg */
+		res = copy_const_value(get_irn_dbg_info(load), c);
+	}
+	return res;
+}  /* can_replace_load_by_const */
+
 /**
  * optimize a Load
  *
@@ -952,9 +1084,10 @@ static unsigned follow_Mem_chain(ir_node *load, ir_node *curr) {
 static unsigned optimize_load(ir_node *load)
 {
 	ldst_info_t *info = get_irn_link(load);
-	ir_node *mem, *ptr, *new_node;
-	ir_entity *ent;
-	unsigned res = 0;
+	ir_node     *mem, *ptr, *value;
+	ir_entity   *ent;
+	long        dummy;
+	unsigned    res = 0;
 
 	/* do NOT touch volatile loads for now */
 	if (get_Load_volatility(load) == volatility_is_volatile)
@@ -972,43 +1105,27 @@ static unsigned optimize_load(ir_node *load)
 	 * 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 (is_Alloc(skip_Proj(mem))) {
-				/* 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;
-					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;
-				}
-			}
-		} else if (is_Alloc(skip_Proj(skip_Cast(ptr)))) {
-				/* 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;
-				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;
+		ir_node *addr = ptr;
+
+		/* find base address */
+		while (is_Sel(addr))
+			addr = get_Sel_ptr(addr);
+		if (is_Alloc(skip_Proj(skip_Cast(addr)))) {
+			/* 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;
+			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;
 		}
 	}
 
 	/* 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 */
@@ -1026,37 +1143,16 @@ static unsigned optimize_load(ir_node *load)
 
 	/* 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;
-			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 (info->projs[pn_Load_res])
-			exchange(info->projs[pn_Load_res], new_node);
-
-		kill_node(load);
-		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))) {
+	value = transform_polymorph_Load(load);
+	if (value == load) {
+		value = NULL;
+		/* check if we can determine the entity that will be loaded */
+		ent = find_constant_entity(ptr);
+		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. */
+			 * 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]) {
@@ -1072,78 +1168,59 @@ static unsigned optimize_load(ir_node *load)
 
 			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. */
+					/* 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;
-						}
-					}
-					kill_node(load);
-					reduce_adr_usage(ptr);
-					return res;
+					 * 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 {
-					ir_node *c = NULL;
-					if (ent->has_initializer) {
-						/* new style initializer */
-						c = find_compound_ent_value(ptr);
-					} else {
-						/* old style initializer */
-						compound_graph_path *path = get_accessed_path(ptr);
-
-						if (path) {
-							assert(is_proper_compound_graph_path(path, get_compound_graph_path_length(path)-1));
-
-							c = get_compound_ent_value_by_path(ent, path);
-							free_compound_graph_path(path);
-						}
-					}
-					if (c != NULL) {
-						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;
-						}
-						kill_node(load);
-						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)));
-						ir_printf("  load: %+F\n", load);
-						ir_printf("  ptr:  %+F\n", ptr);
-						*/
+					/* 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) {
+		/* we completely replace the load by this value */
+		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 (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], value);
+			res |= DF_CHANGED;
+		}
+		kill_node(load);
+		reduce_adr_usage(ptr);
+		return res;
+	}
 
 	/* 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)
+	 * If not, more load cannot be removed in any case. */
+	if (get_irn_n_uses(ptr) <= 1 && get_irn_n_uses(get_base_and_offset(ptr, &dummy)) <= 1)
 		return res;
 
 	/*
@@ -1228,7 +1305,7 @@ static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr) {
 		}
 
 		if (is_Store(pred)) {
-			/* check if we can pass thru this store */
+			/* check if we can pass through this store */
 			ir_alias_relation rel = get_alias_relation(
 				current_ir_graph,
 				get_Store_ptr(pred),
@@ -1270,18 +1347,61 @@ static unsigned follow_Mem_chain_for_Store(ir_node *store, ir_node *curr) {
 	return res;
 }  /* follow_Mem_chain_for_Store */
 
+/** find entity used as base for an address calculation */
+static ir_entity *find_entity(ir_node *ptr)
+{
+	switch(get_irn_opcode(ptr)) {
+	case iro_SymConst:
+		return get_SymConst_entity(ptr);
+	case iro_Sel: {
+		ir_node *pred = get_Sel_ptr(ptr);
+		if (get_irg_frame(get_irn_irg(ptr)) == pred)
+			return get_Sel_entity(ptr);
+
+		return find_entity(pred);
+	}
+	case iro_Sub:
+	case iro_Add: {
+		ir_node *left = get_binop_left(ptr);
+		ir_node *right;
+		if (mode_is_reference(get_irn_mode(left)))
+			return find_entity(left);
+		right = get_binop_right(ptr);
+		if (mode_is_reference(get_irn_mode(right)))
+			return find_entity(right);
+		return NULL;
+	}
+	default:
+		return NULL;
+	}
+}
+
 /**
  * optimize a Store
  *
  * @param store  the Store node
  */
 static unsigned optimize_store(ir_node *store) {
-	ir_node *ptr, *mem;
+	ir_node   *ptr;
+	ir_node   *mem;
+	ir_entity *entity;
 
 	if (get_Store_volatility(store) == volatility_is_volatile)
 		return 0;
 
-	ptr = get_Store_ptr(store);
+	ptr    = get_Store_ptr(store);
+	entity = find_entity(ptr);
+
+	/* a store to an entity which is never read is unnecessary */
+	if (entity != NULL && !(get_entity_usage(entity) & ir_usage_read)) {
+		ldst_info_t *info = get_irn_link(store);
+		if (info->projs[pn_Store_X_except] == NULL) {
+			exchange(info->projs[pn_Store_M], get_Store_mem(store));
+			kill_node(store);
+			reduce_adr_usage(ptr);
+			return DF_CHANGED;
+		}
+	}
 
 	/* Check, if the address of this Store is used more than once.
 	 * If not, this Store cannot be removed in any case. */
@@ -2063,8 +2183,8 @@ void optimize_load_store(ir_graph *irg) {
 	assure_postdoms(irg);
 
 	if (get_opt_alias_analysis()) {
-		assure_irg_address_taken_computed(irg);
-		assure_irp_globals_address_taken_computed();
+		assure_irg_entity_usage_computed(irg);
+		assure_irp_globals_entity_usage_computed();
 	}
 
 	obstack_init(&env.obst);
@@ -2084,6 +2204,7 @@ void optimize_load_store(ir_graph *irg) {
 	/* Handle graph state */
 	if (env.changes) {
 		set_irg_outs_inconsistent(irg);
+		set_irg_entity_usage_state(irg, ir_entity_usage_not_computed);
 	}
 
 	if (env.changes & CF_CHANGED) {