X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Fopt%2Fldstopt.c;h=91347a7bea9076376bfdfabd3af816ae9dc332fa;hb=44faeb9742640d3498eb4482f98eb1255607c4d6;hp=489e2a84b47b7dd22857054b1a8e26ec4e08ceb3;hpb=5fa209c450c82a7ef372ea3a530a693a5d9cfabc;p=libfirm

diff --git a/ir/opt/ldstopt.c b/ir/opt/ldstopt.c
index 489e2a84b..91347a7be 100644
--- a/ir/opt/ldstopt.c
+++ b/ir/opt/ldstopt.c
@@ -386,11 +386,12 @@ 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 +400,7 @@ 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)) {
@@ -419,10 +421,10 @@ 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");
@@ -442,7 +444,7 @@ ptr_arith:
 			/* ok, bounds check finished */
 			++idx;
 		}
-		if (! tarval_is_null(tv)) {
+		if (! tarval_is_null(tmp)) {
 			/* access to some struct/union member */
 			return NULL;
 		}
@@ -500,7 +502,8 @@ 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 {
@@ -538,7 +541,7 @@ 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);
 
@@ -772,6 +775,141 @@ 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
@@ -783,67 +921,39 @@ 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)) {
 			/*
@@ -977,9 +1087,10 @@ ir_node *can_replace_load_by_const(const ir_node *load, ir_node *c) {
 static unsigned optimize_load(ir_node *load)
 {
 	ldst_info_t *info = get_irn_link(load);
-	ir_node *mem, *ptr, *value;
-	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)
@@ -1080,6 +1191,7 @@ static unsigned optimize_load(ir_node *load)
 								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);
 							}
 						}
@@ -1116,8 +1228,8 @@ static unsigned optimize_load(ir_node *load)
 	}
 
 	/* 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;
 
 	/*
@@ -1244,18 +1356,61 @@ 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. */
@@ -2037,8 +2192,8 @@ 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);
@@ -2058,6 +2213,7 @@ 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) {