X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Fbe%2Fbespill.c;h=aabdbfec2a009d245065cbd519af1a3f87948bf5;hb=d920844bd5cd3296b03bb281ce43782967e0ce65;hp=697a05a732b3e59f4ccb58fe84452d35c949cae9;hpb=b3a557ce967915e127eca5460196b4eb4c59718c;p=libfirm

diff --git a/ir/be/bespill.c b/ir/be/bespill.c
index 697a05a73..aabdbfec2 100644
--- a/ir/be/bespill.c
+++ b/ir/be/bespill.c
@@ -58,11 +58,25 @@ struct _spill_env_t {
 	set *spill_ctxs;
 	set *spills;				/**< all spill_info_t's, which must be placed */
 	pset *mem_phis;				/**< set of all special spilled phis. allocated and freed separately */
-	decide_irn_t is_mem_phi;	/**< callback func to decide if a phi needs special spilling */
-	void *data;					/**< data passed to all callbacks */
+	ir_node **copies;			/**< set of copies placed because of phi spills */
 	DEBUG_ONLY(firm_dbg_module_t *dbg;)
 };
 
+/* associated Phi -> Spill*/
+typedef struct _phi_spill_assoc_t {
+	ir_node *phi;
+	ir_node *spill;
+} phi_spill_assoc_t;
+
+/**
+ * Compare two Phi->Spill associations.
+ */
+static int cmp_phi_spill_assoc(const void *a, const void *b, size_t n) {
+	const phi_spill_assoc_t *p1 = a;
+	const phi_spill_assoc_t *p2 = b;
+	return p1->phi != p2->phi;
+}
+
 /**
  * compare two spill contexts.
  */
@@ -89,24 +103,26 @@ void be_set_spill_env_dbg_module(spill_env_t *env, firm_dbg_module_t *dbg) {
 )
 
 /* Creates a new spill environment. */
-spill_env_t *be_new_spill_env(const be_chordal_env_t *chordal_env, decide_irn_t is_mem_phi, void *data) {
-	spill_env_t *env = xmalloc(sizeof(env[0]));
-	env->spill_ctxs  = new_set(cmp_spillctx, 1024);
-	env->spills      = new_set(cmp_spillinfo, 1024);
-	env->cls         = chordal_env->cls;
-	env->is_mem_phi  = is_mem_phi;
-	env->data        = data;
-	env->chordal_env = chordal_env;
+spill_env_t *be_new_spill_env(const be_chordal_env_t *chordal_env) {
+	spill_env_t *env	= xmalloc(sizeof(env[0]));
+	env->spill_ctxs		= new_set(cmp_spillctx, 1024);
+	env->spills			= new_set(cmp_spillinfo, 1024);
+	env->cls			= chordal_env->cls;
+	env->chordal_env	= chordal_env;
+	env->mem_phis		= pset_new_ptr_default();
+	env->copies			= NEW_ARR_F(ir_node*, 0);
 	obstack_init(&env->obst);
 	return env;
 }
 
 /* Deletes a spill environment. */
-void be_delete_spill_env(spill_env_t *senv) {
-	del_set(senv->spill_ctxs);
-	del_set(senv->spills);
-	obstack_free(&senv->obst, NULL);
-	free(senv);
+void be_delete_spill_env(spill_env_t *env) {
+	del_set(env->spill_ctxs);
+	del_set(env->spills);
+	del_pset(env->mem_phis);
+	DEL_ARR_F(env->copies);
+	obstack_free(&env->obst, NULL);
+	free(env);
 }
 
 /**
@@ -128,6 +144,26 @@ static spill_ctx_t *be_get_spill_ctx(set *sc, ir_node *to_spill, ir_node *ctx_ir
 	return set_insert(sc, &templ, sizeof(templ), HASH_COMBINE(HASH_PTR(to_spill), HASH_PTR(ctx_irn)));
 }
 
+/**
+ * Schedules a node after an instruction. (That is the place after all projs and phis
+ * that are scheduled after the instruction)
+ */
+static void sched_add_after_insn(ir_node *sched_after, ir_node *node) {
+	ir_node *next = sched_next(sched_after);
+	while(!sched_is_end(next)) {
+		if(!is_Proj(next) && !is_Phi(next))
+			break;
+		next = sched_next(next);
+	}
+
+	if(sched_is_end(next)) {
+		next = sched_last(get_nodes_block(sched_after));
+		sched_add_after(next, node);
+	} else {
+		sched_add_before(next, node);
+	}
+}
+
 /**
  * Creates a spill.
  *
@@ -139,17 +175,92 @@ static spill_ctx_t *be_get_spill_ctx(set *sc, ir_node *to_spill, ir_node *ctx_ir
  */
 static ir_node *be_spill_irn(spill_env_t *senv, ir_node *irn, ir_node *ctx_irn) {
 	spill_ctx_t *ctx;
+	const be_main_env_t *env = senv->chordal_env->birg->main_env;
 	DBG((senv->dbg, LEVEL_1, "%+F in ctx %+F\n", irn, ctx_irn));
 
+	// Has the value already been spilled?
 	ctx = be_get_spill_ctx(senv->spill_ctxs, irn, ctx_irn);
-	if(!ctx->spill) {
-		const be_main_env_t *env = senv->chordal_env->birg->main_env;
-		ctx->spill = be_spill(env->arch_env, irn, ctx_irn);
+	if(ctx->spill)
+		return ctx->spill;
+
+	/* Trying to spill an already spilled value, no need for a new spill
+	 * node then, we can simply connect to the same one for this reload
+	 */
+	if(be_is_Reload(irn)) {
+		return get_irn_n(irn, be_pos_Reload_mem);
 	}
 
+	ctx->spill = be_spill(env->arch_env, irn, ctx_irn);
+	sched_add_after_insn(irn, ctx->spill);
+
 	return ctx->spill;
 }
 
+/**
+ * Removes all copies introduced for phi-spills
+ */
+static void remove_copies(spill_env_t *env) {
+	int i;
+
+	for(i = 0; i < ARR_LEN(env->copies); ++i) {
+		ir_node *node = env->copies[i];
+		ir_node *src;
+		const ir_edge_t *edge, *ne;
+
+		assert(be_is_Copy(node));
+
+		src = be_get_Copy_op(node);
+		foreach_out_edge_safe(node, edge, ne) {
+			ir_node *user = get_edge_src_irn(edge);
+			int user_pos  = get_edge_src_pos(edge);
+
+			set_irn_n(user, user_pos, src);
+		}
+	}
+
+	ARR_SETLEN(ir_node*, env->copies, 0);
+}
+
+static INLINE ir_node *skip_projs(ir_node *node) {
+	while(is_Proj(node)) {
+		node = sched_next(node);
+		assert(!sched_is_end(node));
+	}
+
+	return node;
+}
+
+/**
+ * Searchs the schedule backwards until we reach the first use or def of a
+ * value or a phi.
+ * Returns the node before this node (so that you can do sched_add_before)
+ */
+static ir_node *find_last_use_def(spill_env_t *env, ir_node *block, ir_node *value) {
+	ir_node *node, *last;
+
+	last = NULL;
+	sched_foreach_reverse(block, node) {
+		int i, arity;
+
+		if(is_Phi(node)) {
+			return last;
+		}
+		if(value == node) {
+			return skip_projs(last);
+		}
+		for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
+			ir_node *arg = get_irn_n(node, i);
+			if(arg == value) {
+				return skip_projs(node);
+			}
+		}
+		last = node;
+	}
+
+	// simply return first node if no def or use found
+	return sched_first(block);
+}
+
 /**
  * If the first usage of a Phi result would be out of memory
  * there is no sense in allocating a register for it.
@@ -162,33 +273,63 @@ static ir_node *be_spill_irn(spill_env_t *senv, ir_node *irn, ir_node *ctx_irn)
  *
  * @return a be_Spill node
  */
-static ir_node *be_spill_phi(spill_env_t *senv, ir_node *phi, ir_node *ctx_irn) {
-	int i, n = get_irn_arity(phi);
-	ir_node **ins, *bl = get_nodes_block(phi);
-	ir_graph *irg = senv->chordal_env->irg;
+static ir_node *spill_phi(spill_env_t *senv, ir_node *phi, ir_node *ctx_irn, set *already_visited_phis, bitset_t *bs) {
+	int         i;
+	int arity = get_irn_arity(phi);
+	ir_graph    *irg      = senv->chordal_env->irg;
+	ir_node     *bl       = get_nodes_block(phi);
+	ir_node     **ins, *phi_spill;
+	phi_spill_assoc_t key;
 	spill_ctx_t *ctx;
 
 	assert(is_Phi(phi));
 	DBG((senv->dbg, LEVEL_1, "%+F in ctx %+F\n", phi, ctx_irn));
 
+	/* build a new PhiM */
+	NEW_ARR_A(ir_node *, ins, arity);
+	for (i = 0; i < arity; ++i) {
+		ins[i] = new_r_Bad(irg);
+	}
+	phi_spill = new_r_Phi(senv->chordal_env->irg, bl, arity, ins, mode_M);
+	key.phi   = phi;
+	key.spill = phi_spill;
+	set_insert(already_visited_phis, &key, sizeof(key), HASH_PTR(phi));
+	bitset_set(bs, get_irn_idx(phi));
+
 	/* search an existing spill for this context */
 	ctx = be_get_spill_ctx(senv->spill_ctxs, phi, ctx_irn);
 
 	/* if not found spill the phi */
-	if(!ctx->spill) {
-		/* build a new PhiM */
-		NEW_ARR_A(ir_node *, ins, n);
-		for (i=0; i<n; ++i) {
+	if (! ctx->spill) {
+		/* collect all arguments of the phi */
+		for (i = 0; i < arity; ++i) {
 			ir_node *arg = get_irn_n(phi, i);
 			ir_node *sub_res;
-
-			if(is_Phi(arg) && pset_find_ptr(senv->mem_phis, arg))
-				sub_res = be_spill_phi(senv, arg, ctx_irn);
-			else
+			phi_spill_assoc_t *entry;
+
+			if(is_Phi(arg) && pset_find_ptr(senv->mem_phis, arg)) {
+				// looping edge?
+				if(arg == phi) {
+					sub_res = phi_spill;
+				} else if (! bitset_is_set(bs, get_irn_idx(arg))) {
+					sub_res = spill_phi(senv, arg, ctx_irn, already_visited_phis, bs);
+				} else {
+					/* we already visited the argument phi: get it's spill */
+					key.phi   = arg;
+					key.spill = NULL;
+					entry     = set_find(already_visited_phis, &key, sizeof(key), HASH_PTR(arg));
+					assert(entry && "argument phi already visited, but no spill found?!?");
+					sub_res   = entry->spill;
+					assert(sub_res && "spill missing?!?");
+				}
+			} else {
 				sub_res = be_spill_irn(senv, arg, ctx_irn);
-			ins[i] = sub_res;
+			}
+
+			set_irn_n(phi_spill, i, sub_res);
 		}
-		ctx->spill = new_r_Phi(senv->chordal_env->irg, bl, n, ins, mode_M);
+
+		ctx->spill = phi_spill;
 	}
 	return ctx->spill;
 }
@@ -197,17 +338,22 @@ static ir_node *be_spill_phi(spill_env_t *senv, ir_node *phi, ir_node *ctx_irn)
  * Spill a node.
  *
  * @param senv      the spill environment
- * @param irn       the node that should be spilled
- * @param ctx_irn   an user of the spilled node
+ * @param to_spill  the node that should be spilled
  *
  * @return a be_Spill node
  */
 static ir_node *be_spill_node(spill_env_t *senv, ir_node *to_spill) {
-	ir_node *res;
-	if (pset_find_ptr(senv->mem_phis, to_spill))
-		res = be_spill_phi(senv, to_spill, to_spill);
-	else
+	ir_graph *irg = get_irn_irg(to_spill);
+	ir_node  *res;
+
+	if (pset_find_ptr(senv->mem_phis, to_spill)) {
+		set *already_visited_phis = new_set(cmp_phi_spill_assoc, 10);
+		bitset_t *bs = bitset_alloca(get_irg_last_idx(irg));
+		res = spill_phi(senv, to_spill, to_spill, already_visited_phis, bs);
+		del_set(already_visited_phis);
+	} else {
 		res = be_spill_irn(senv, to_spill, to_spill);
+	}
 
 	return res;
 }
@@ -330,55 +476,65 @@ static ir_node *do_remat(spill_env_t *senv, ir_node *spilled, ir_node *reloader)
 	return res;
 }
 
-/**
- * Walker: fills the mem_phis set by evaluating Phi nodes
- * using the is_mem_phi() callback.
- */
-static void phi_walker(ir_node *irn, void *env) {
-	spill_env_t *senv = env;
-
-	if (is_Phi(irn)) {
-		const arch_env_t *arch = senv->chordal_env->birg->main_env->arch_env;
-		if (arch_irn_has_reg_class(arch, irn, 0, senv->cls) &&
-			senv->is_mem_phi(irn, senv->data)) {
-			DBG((senv->dbg, LEVEL_1, "  %+F\n", irn));
-			pset_insert_ptr(senv->mem_phis, irn);
-		}
+void be_spill_phi(spill_env_t *env, ir_node *node) {
+	int i, arity;
+
+	assert(is_Phi(node));
+
+	pset_insert_ptr(env->mem_phis, node);
+
+	/* We have to place copy nodes in the predecessor blocks to temporarily
+	 * produce new values that get separate spill slots
+	 */
+	for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
+		ir_node *pred_block, *arg, *copy, *insert_point;
+
+		/* Don't do anything for looping edges (there's no need
+		 * and placing copies here breaks stuff as it suddenly
+		 * generates new living values through the whole loop)
+		 */
+		arg = get_irn_n(node, i);
+		if(arg == node)
+			continue;
+
+		pred_block = get_Block_cfgpred_block(get_nodes_block(node), i);
+		copy = be_new_Copy(env->cls, get_irn_irg(arg), pred_block, arg);
+
+		ARR_APP1(ir_node*, env->copies, copy);
+		insert_point = find_last_use_def(env, pred_block, arg);
+		sched_add_before(insert_point, copy);
+
+		set_irn_n(node, i, copy);
 	}
 }
 
-void be_insert_spills_reloads(spill_env_t *senv, pset *reload_set) {
-	const arch_env_t *aenv = senv->chordal_env->birg->main_env->arch_env;
-	ir_graph *irg          = senv->chordal_env->irg;
-	ir_node *irn;
+void be_insert_spills_reloads(spill_env_t *env) {
+	const arch_env_t *arch_env = env->chordal_env->birg->main_env->arch_env;
+	ir_node *node;
 	spill_info_t *si;
-	pdeq *possibly_dead;
-
-	/* get all special spilled phis */
-	DBG((senv->dbg, LEVEL_1, "Mem-phis:\n"));
-	senv->mem_phis = pset_new_ptr_default();
-	irg_walk_graph(senv->chordal_env->irg, phi_walker, NULL, senv);
 
-	/* Add reloads for mem_phis */
-	/* BETTER: These reloads (1) should only be inserted, if they are really needed */
-	DBG((senv->dbg, LEVEL_1, "Reloads for mem-phis:\n"));
-	for(irn = pset_first(senv->mem_phis); irn; irn = pset_next(senv->mem_phis)) {
+	DBG((env->dbg, LEVEL_1, "Reloads for mem-phis:\n"));
+	foreach_pset(env->mem_phis, node) {
 		const ir_edge_t *e;
-		DBG((senv->dbg, LEVEL_1, " Mem-phi %+F\n", irn));
-		foreach_out_edge(irn, e) {
+
+		assert(is_Phi(node));
+
+		/* Add reloads for mem_phis */
+		/* BETTER: These reloads (1) should only be inserted, if they are really needed */
+		DBG((env->dbg, LEVEL_1, " Mem-phi %+F\n", node));
+		foreach_out_edge(node, e) {
 			ir_node *user = e->src;
-			if (is_Phi(user) && !pset_find_ptr(senv->mem_phis, user)) {
-					ir_node *use_bl = get_nodes_block(user);
-					DBG((senv->dbg, LEVEL_1, " non-mem-phi user %+F\n", user));
-					be_add_reload_on_edge(senv, irn, use_bl, e->pos); /* (1) */
+			if (is_Phi(user) && !pset_find_ptr(env->mem_phis, user)) {
+				ir_node *use_bl = get_nodes_block(user);
+				DBG((env->dbg, LEVEL_1, " non-mem-phi user %+F\n", user));
+				be_add_reload_on_edge(env, node, use_bl, e->pos); /* (1) */
 			}
 		}
 	}
 
 	/* process each spilled node */
-	DBG((senv->dbg, LEVEL_1, "Insert spills and reloads:\n"));
-	possibly_dead = new_pdeq();
-	for(si = set_first(senv->spills); si; si = set_next(senv->spills)) {
+	DBG((env->dbg, LEVEL_1, "Insert spills and reloads:\n"));
+	for(si = set_first(env->spills); si; si = set_next(env->spills)) {
 		reloader_t *rld;
 		ir_mode *mode = get_irn_mode(si->spilled_node);
 		pset *values = pset_new_ptr(16);
@@ -388,79 +544,78 @@ void be_insert_spills_reloads(spill_env_t *senv, pset *reload_set) {
 			ir_node *new_val;
 
 			/* the spill for this reloader */
-			ir_node *spill   = be_spill_node(senv, si->spilled_node);
+			ir_node *spill   = be_spill_node(env, si->spilled_node);
 
 #ifdef REMAT
-			if (check_remat_conditions(senv, spill, si->spilled_node, rld->reloader)) {
-				new_val = do_remat(senv, si->spilled_node, rld->reloader);
-				pdeq_putl(possibly_dead, spill);
-			}
-			else
+			if (check_remat_conditions(env, spill, si->spilled_node, rld->reloader)) {
+				new_val = do_remat(env, si->spilled_node, rld->reloader);
+			} else
 #endif
 				/* do a reload */
-				new_val = be_reload(aenv, senv->cls, rld->reloader, mode, spill);
+				new_val = be_reload(arch_env, env->cls, rld->reloader, mode, spill);
 
-			DBG((senv->dbg, LEVEL_1, " %+F of %+F before %+F\n", new_val, si->spilled_node, rld->reloader));
+			DBG((env->dbg, LEVEL_1, " %+F of %+F before %+F\n", new_val, si->spilled_node, rld->reloader));
 			pset_insert_ptr(values, new_val);
-			if(reload_set)
-				pset_insert_ptr(reload_set, new_val);
 		}
 
 		/* introduce copies, rewire the uses */
 		assert(pset_count(values) > 0 && "???");
 		pset_insert_ptr(values, si->spilled_node);
-		be_ssa_constr_set_ignore(senv->chordal_env->dom_front, values, senv->mem_phis);
+		be_ssa_constr_set_ignore(env->chordal_env->dom_front, values, env->mem_phis);
 
 		del_pset(values);
 	}
 
-	foreach_pset(senv->mem_phis, irn) {
-		int i, n;
-		for (i = 0, n = get_irn_arity(irn); i < n; ++i) {
-			pdeq_putl(possibly_dead, get_irn_n(irn, i));
-			set_irn_n(irn, i, new_r_Bad(senv->chordal_env->irg));
-		}
-		sched_remove(irn);
-	}
-
-	/* check if possibly dead nodes are really dead yet */
-	while (! pdeq_empty(possibly_dead)) {
-		ir_node *irn = pdeq_getr(possibly_dead);
-		const ir_edge_t *edge = get_irn_out_edge_first(irn);
+	remove_copies(env);
 
-		if (! edge) {
-			int i;
-			for (i = get_irn_arity(irn) - 1; i >= 0; --i) {
-				pdeq_putl(possibly_dead, get_irn_n(irn, i));
-				set_irn_n(irn, i, new_r_Bad(senv->chordal_env->irg));
-			}
-			sched_remove(irn);
-		}
-	}
-	del_pdeq(possibly_dead);
-	del_pset(senv->mem_phis);
+	// reloads are placed now, but we might reuse the spill environment for further spilling decisions
+	del_set(env->spills);
+	env->spills = new_set(cmp_spillinfo, 1024);
 }
 
-void be_add_reload(spill_env_t *senv, ir_node *to_spill, ir_node *before) {
+void be_add_reload(spill_env_t *env, ir_node *to_spill, ir_node *before) {
 	spill_info_t templ, *res;
 	reloader_t *rel;
 
+	assert(sched_is_scheduled(before));
+	assert(arch_irn_consider_in_reg_alloc(env->chordal_env->birg->main_env->arch_env, env->cls, to_spill));
+
 	templ.spilled_node = to_spill;
 	templ.reloaders    = NULL;
-	res = set_insert(senv->spills, &templ, sizeof(templ), HASH_PTR(to_spill));
+	res = set_insert(env->spills, &templ, sizeof(templ), HASH_PTR(to_spill));
 
-	rel           = obstack_alloc(&senv->obst, sizeof(rel[0]));
+	rel           = obstack_alloc(&env->obst, sizeof(rel[0]));
 	rel->reloader = before;
 	rel->next     = res->reloaders;
 	res->reloaders = rel;
 }
 
-void be_add_reload_on_edge(spill_env_t *senv, ir_node *to_spill, ir_node *bl, int pos) {
-	ir_node *insert_bl = get_irn_arity(bl) == 1 ? sched_first(bl) : get_Block_cfgpred_block(bl, pos);
-	be_add_reload(senv, to_spill, insert_bl);
-}
+void be_add_reload_on_edge(spill_env_t *env, ir_node *to_spill, ir_node *block, int pos) {
+	ir_node *predblock, *last;
+
+	/* simply add the reload to the beginning of the block if we only have 1 predecessor
+	 * (we don't need to check for phis as there can't be any in a block with only 1 pred)
+	 */
+	if(get_Block_n_cfgpreds(block) == 1) {
+		assert(!is_Phi(sched_first(block)));
+		be_add_reload(env, to_spill, sched_first(block));
+		return;
+	}
+
+	/* We have to reload the value in pred-block */
+	predblock = get_Block_cfgpred_block(block, pos);
+	last = sched_last(predblock);
 
+	/* we might have projs and keepanys behind the jump... */
+	while(is_Proj(last) || be_is_Keep(last)) {
+		last = sched_prev(last);
+		assert(!sched_is_end(last));
+	}
+	assert(is_cfop(last));
 
+	// add the reload before the (cond-)jump
+	be_add_reload(env, to_spill, last);
+}
 
 /****************************************
 
@@ -523,7 +678,7 @@ static void compute_spill_slots_walker(ir_node *spill, void *env) {
 			struct _arch_env_t *arch_env     = ssenv->cenv->birg->main_env->arch_env;
 			const arch_register_class_t *cls = arch_get_irn_reg_class(arch_env, spill, be_pos_Spill_val);
 			int size = get_mode_size_bytes(arch_register_class_mode(cls));
-			assert(ss->size == size && "Different sizes for the same spill slot are not allowed.");
+			assert((int) ss->size == size && "Different sizes for the same spill slot are not allowed.");
 			for (irn = pset_first(ss->members); irn; irn = pset_next(ss->members)) {
 				/* use values_interfere here, because it uses the dominance check,
 					 which does work for values in memory */
@@ -540,8 +695,8 @@ static void compute_spill_slots_walker(ir_node *spill, void *env) {
  * qsort compare function, sort spill slots by size.
  */
 static int ss_sorter(const void *v1, const void *v2) {
-	const spill_slot_t **ss1 = v1;
-	const spill_slot_t **ss2 = v2;
+	const spill_slot_t **ss1 = (const spill_slot_t **)v1;
+	const spill_slot_t **ss2 = (const spill_slot_t **)v2;
 	return ((int) (*ss2)->size) - ((int) (*ss1)->size);
 }
 
@@ -638,21 +793,21 @@ interf_detected: /*nothing*/ ;
  * mode but different alignments.
  */
 static ir_type *get_spill_type(pmap *types, spill_slot_t *ss) {
-  pmap_entry *e = pmap_find(types, ss->largest_mode);
-  ir_type *res;
+	pmap_entry *e = pmap_find(types, ss->largest_mode);
+	ir_type *res;
 
-  if (! e) {
+	if (! e) {
 		char buf[64];
-    snprintf(buf, sizeof(buf), "spill_slot_type_%s", get_mode_name(ss->largest_mode));
-    res = new_type_primitive(new_id_from_str(buf), ss->largest_mode);
+		snprintf(buf, sizeof(buf), "spill_slot_type_%s", get_mode_name(ss->largest_mode));
+		res = new_type_primitive(new_id_from_str(buf), ss->largest_mode);
 		set_type_alignment_bytes(res, ss->align);
-    pmap_insert(types, ss->largest_mode, res);
-  }
-  else {
-    res = e->value;
+		pmap_insert(types, ss->largest_mode, res);
+	} else {
+		res = e->value;
 		assert(get_type_alignment_bytes(res) == (int)ss->align);
 	}
-  return res;
+
+	return res;
 }
 
 /**
@@ -664,12 +819,17 @@ static ir_type *get_spill_type(pmap *types, spill_slot_t *ss) {
  */
 static void assign_entities(ss_env_t *ssenv, int n_slots, spill_slot_t *ss[]) {
 	int i, offset, frame_align;
-	ir_type *frame = get_irg_frame_type(ssenv->cenv->irg);
+	ir_type *frame;
+
+	/* do not align the frame if no spill slots are needed */
+	if (n_slots <= 0)
+		return;
+
+	frame = get_irg_frame_type(ssenv->cenv->irg);
 
 	/* aligning by increasing frame size */
-	offset = get_type_size_bits(frame) / 8;
+	offset = get_type_size_bytes(frame);
 	offset = round_up2(offset, ALIGN_SPILL_AREA);
-	set_type_size_bytes(frame, -1);
 
 	/* create entities and assign offsets according to size and alignment*/
 	for (i = 0; i < n_slots; ++i) {
@@ -695,6 +855,7 @@ static void assign_entities(ss_env_t *ssenv, int n_slots, spill_slot_t *ss[]) {
 			be_set_Spill_entity(irn, spill_ent);
 	}
 
+
 	/* set final size of stack frame */
 	frame_align = get_type_alignment_bytes(frame);
 	set_type_size_bytes(frame, round_up2(offset, frame_align));