X-Git-Url: http://wien.tomnetworks.com/gitweb/?a=blobdiff_plain;f=mono%2Fmini%2Fliveness.c;h=36412f86a0f318dee5ddf73f81b08a615c10ceea;hb=72bb61054d706a82a178dc16a4b8a550e62e034f;hp=dbc3edcb9df1edb01efad82f006cdb6676124ac1;hpb=75df74a96c33af7a99e16e4281272f1b67334a48;p=mono.git

diff --git a/mono/mini/liveness.c b/mono/mini/liveness.c
index dbc3edcb9df..36412f86a0f 100644
--- a/mono/mini/liveness.c
+++ b/mono/mini/liveness.c
@@ -21,27 +21,39 @@
 #define BITS_PER_CHUNK 32
 #endif
 
+/* 
+ * The liveness2 pass can't handle long vars on 32 bit platforms because the component
+ * vars have the same 'idx'.
+ */
+#if SIZEOF_VOID_P == 8
+//#define ENABLE_LIVENESS2
+#endif
+
+#ifdef ENABLE_LIVENESS2
+static void mono_analyze_liveness2 (MonoCompile *cfg);
+#endif
+
+static void
+optimize_initlocals (MonoCompile *cfg);
+
+static void
+optimize_initlocals2 (MonoCompile *cfg);
+
 /* mono_bitset_mp_new:
  * 
  * allocates a MonoBitSet inside a memory pool
  */
 static inline MonoBitSet* 
-mono_bitset_mp_new (MonoMemPool *mp,  guint32 max_size)
+mono_bitset_mp_new (MonoMemPool *mp, guint32 size, guint32 max_size)
 {
-	int size = mono_bitset_alloc_size (max_size, 0);
-	gpointer mem;
-
-	mem = mono_mempool_alloc0 (mp, size);
+	guint8 *mem = mono_mempool_alloc0 (mp, size);
 	return mono_bitset_mem_new (mem, max_size, MONO_BITSET_DONT_FREE);
 }
 
 static inline MonoBitSet* 
-mono_bitset_mp_new_noinit (MonoMemPool *mp,  guint32 max_size)
+mono_bitset_mp_new_noinit (MonoMemPool *mp, guint32 size, guint32 max_size)
 {
-	int size = mono_bitset_alloc_size (max_size, 0);
-	gpointer mem;
-
-	mem = mono_mempool_alloc (mp, size);
+	guint8 *mem = mono_mempool_alloc (mp, size);
 	return mono_bitset_mem_new (mem, max_size, MONO_BITSET_DONT_FREE);
 }
 
@@ -76,9 +88,10 @@ update_live_range (MonoCompile *cfg, int idx, int block_dfn, int tree_pos)
 static void
 update_gen_kill_set (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *inst, int inst_num)
 {
-	int arity = mono_burg_arity [inst->opcode];
+	int arity;
 	int max_vars = cfg->num_varinfo;
 
+	arity = mono_burg_arity [inst->opcode];
 	if (arity)
 		update_gen_kill_set (cfg, bb, inst->inst_i0, inst_num);
 
@@ -107,13 +120,6 @@ update_gen_kill_set (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *inst, int i
 				int idx = affected_variable->variable_index;
 				MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 				g_assert (idx < max_vars);
-				if ((bb->region != -1) && !MONO_BBLOCK_IS_IN_REGION (bb, MONO_REGION_TRY)) {
-					/*
-					 * Variables used in exception regions can't be allocated to 
-					 * registers.
-					 */
-					cfg->varinfo [vi->idx]->flags |= MONO_INST_VOLATILE;
-				}
 				update_live_range (cfg, idx, bb->dfn, inst_num); 
 				if (!mono_bitset_test_fast (bb->kill_set, idx))
 					mono_bitset_set_fast (bb->gen_set, idx);
@@ -130,13 +136,6 @@ update_gen_kill_set (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *inst, int i
 				g_assert (idx < max_vars);
 				//if (arity > 0)
 					//g_assert (inst->inst_i1->opcode != OP_PHI);
-				if ((bb->region != -1) && !MONO_BBLOCK_IS_IN_REGION (bb, MONO_REGION_TRY)) {
-					/*
-					 * Variables used in exception regions can't be allocated to 
-					 * registers.
-					 */
-					cfg->varinfo [vi->idx]->flags |= MONO_INST_VOLATILE;
-				}
 				update_live_range (cfg, idx, bb->dfn, inst_num); 
 				mono_bitset_set_fast (bb->kill_set, idx);
 				if (inst->ssa_op == MONO_SSA_STORE)
@@ -145,7 +144,7 @@ update_gen_kill_set (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *inst, int i
 				affected_variable = affected_variable->next;
 			}
 		}
-	} else if (inst->opcode == CEE_JMP) {
+	} else if (inst->opcode == OP_JMP) {
 		/* Keep arguments live! */
 		int i;
 		for (i = 0; i < cfg->num_varinfo; i++) {
@@ -158,16 +157,16 @@ update_gen_kill_set (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *inst, int i
 } 
 
 static void
-update_volatile (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *inst, int inst_num)
+update_volatile (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *inst)
 {
 	int arity = mono_burg_arity [inst->opcode];
 	int max_vars = cfg->num_varinfo;
 
 	if (arity)
-		update_volatile (cfg, bb, inst->inst_i0, inst_num);
+		update_volatile (cfg, bb, inst->inst_i0);
 
 	if (arity > 1)
-		update_volatile (cfg, bb, inst->inst_i1, inst_num);
+		update_volatile (cfg, bb, inst->inst_i1);
 
 	if (inst->ssa_op & MONO_SSA_LOAD_STORE) {
 		MonoLocalVariableList* affected_variables;
@@ -199,17 +198,54 @@ update_volatile (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *inst, int inst_
 static void
 visit_bb (MonoCompile *cfg, MonoBasicBlock *bb, GSList **visited)
 {
-	int i, tree_num;
-	MonoInst *inst;
+	int i;
+	MonoInst *ins;
 
 	if (g_slist_find (*visited, bb))
 		return;
 
-	if (cfg->aliasing_info != NULL)
-		mono_aliasing_initialize_code_traversal (cfg->aliasing_info, bb);
-	
-	for (tree_num = 0, inst = bb->code; inst; inst = inst->next, tree_num++) {
-		update_volatile (cfg, bb, inst, tree_num);
+	if (cfg->new_ir) {
+		for (ins = bb->code; ins; ins = ins->next) {
+			const char *spec = INS_INFO (ins->opcode);
+			int regtype, srcindex, sreg;
+
+			if (ins->opcode == OP_NOP)
+				continue;
+
+			/* DREG */
+			regtype = spec [MONO_INST_DEST];
+			g_assert (((ins->dreg == -1) && (regtype == ' ')) || ((ins->dreg != -1) && (regtype != ' ')));
+				
+			if ((ins->dreg != -1) && get_vreg_to_inst (cfg, ins->dreg)) {
+				MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
+				int idx = var->inst_c0;
+				MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
+
+				cfg->varinfo [vi->idx]->flags |= MONO_INST_VOLATILE;
+			}
+			
+			/* SREGS */
+			for (srcindex = 0; srcindex < 2; ++srcindex) {
+				regtype = spec [(srcindex == 0) ? MONO_INST_SRC1 : MONO_INST_SRC2];
+				sreg = srcindex == 0 ? ins->sreg1 : ins->sreg2;
+
+				g_assert (((sreg == -1) && (regtype == ' ')) || ((sreg != -1) && (regtype != ' ')));
+				if ((sreg != -1) && get_vreg_to_inst (cfg, sreg)) {
+					MonoInst *var = get_vreg_to_inst (cfg, sreg);
+					int idx = var->inst_c0;
+					MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
+
+					cfg->varinfo [vi->idx]->flags |= MONO_INST_VOLATILE;
+				}
+			}
+		}
+	} else {
+		if (cfg->aliasing_info != NULL)
+			mono_aliasing_initialize_code_traversal (cfg->aliasing_info, bb);
+
+		for (ins = bb->code; ins; ins = ins->next) {
+			update_volatile (cfg, bb, ins);
+		}
 	}
 
 	*visited = g_slist_append (*visited, bb);
@@ -223,8 +259,8 @@ visit_bb (MonoCompile *cfg, MonoBasicBlock *bb, GSList **visited)
 	}
 }
 
-static void
-handle_exception_clauses (MonoCompile *cfg)
+void
+mono_liveness_handle_exception_clauses (MonoCompile *cfg)
 {
 	MonoBasicBlock *bb;
 	GSList *visited = NULL;
@@ -247,6 +283,105 @@ handle_exception_clauses (MonoCompile *cfg)
 	g_slist_free (visited);
 }
 
+static inline void
+update_live_range2 (MonoMethodVar *var, int abs_pos)
+{
+	if (var->range.first_use.abs_pos > abs_pos)
+		var->range.first_use.abs_pos = abs_pos;
+
+	if (var->range.last_use.abs_pos < abs_pos)
+		var->range.last_use.abs_pos = abs_pos;
+}
+
+static void
+analyze_liveness_bb (MonoCompile *cfg, MonoBasicBlock *bb)
+{
+	MonoInst *ins;
+	int sreg, inst_num;
+	MonoMethodVar *vars = cfg->vars;
+	guint32 abs_pos = (bb->dfn << 16);
+	
+	for (inst_num = 0, ins = bb->code; ins; ins = ins->next, inst_num += 2) {
+		const char *spec = INS_INFO (ins->opcode);
+
+#ifdef DEBUG_LIVENESS
+			printf ("\t"); mono_print_ins (ins);
+#endif
+
+		if (ins->opcode == OP_NOP)
+			continue;
+
+		if (ins->opcode == OP_LDADDR) {
+			MonoInst *var = ins->inst_p0;
+			int idx = var->inst_c0;
+			MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
+
+#ifdef DEBUG_LIVENESS
+			printf ("\tGEN: R%d(%d)\n", var->dreg, idx);
+#endif
+			update_live_range2 (&vars [idx], abs_pos + inst_num); 
+			if (!mono_bitset_test_fast (bb->kill_set, idx))
+				mono_bitset_set_fast (bb->gen_set, idx);
+			vi->spill_costs += SPILL_COST_INCREMENT;
+		}				
+
+		/* SREGs must come first, so MOVE r <- r is handled correctly */
+
+		/* SREG1 */
+		sreg = ins->sreg1;
+		if ((spec [MONO_INST_SRC1] != ' ') && get_vreg_to_inst (cfg, sreg)) {
+			MonoInst *var = get_vreg_to_inst (cfg, sreg);
+			int idx = var->inst_c0;
+			MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
+
+#ifdef DEBUG_LIVENESS
+			printf ("\tGEN: R%d(%d)\n", sreg, idx);
+#endif
+			update_live_range2 (&vars [idx], abs_pos + inst_num); 
+			if (!mono_bitset_test_fast (bb->kill_set, idx))
+				mono_bitset_set_fast (bb->gen_set, idx);
+			vi->spill_costs += SPILL_COST_INCREMENT;
+		}
+
+		/* SREG2 */
+		sreg = ins->sreg2;
+		if ((spec [MONO_INST_SRC2] != ' ') && get_vreg_to_inst (cfg, sreg)) {
+			MonoInst *var = get_vreg_to_inst (cfg, sreg);
+			int idx = var->inst_c0;
+			MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
+
+#ifdef DEBUG_LIVENESS
+			printf ("\tGEN: R%d(%d)\n", sreg, idx);
+#endif
+			update_live_range2 (&vars [idx], abs_pos + inst_num); 
+			if (!mono_bitset_test_fast (bb->kill_set, idx))
+				mono_bitset_set_fast (bb->gen_set, idx);
+			vi->spill_costs += SPILL_COST_INCREMENT;
+		}
+
+		/* DREG */
+		if ((spec [MONO_INST_DEST] != ' ') && get_vreg_to_inst (cfg, ins->dreg)) {
+			MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
+			int idx = var->inst_c0;
+			MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
+
+			if (MONO_IS_STORE_MEMBASE (ins)) {
+				update_live_range2 (&vars [idx], abs_pos + inst_num); 
+				if (!mono_bitset_test_fast (bb->kill_set, idx))
+					mono_bitset_set_fast (bb->gen_set, idx);
+				vi->spill_costs += SPILL_COST_INCREMENT;
+			} else {
+#ifdef DEBUG_LIVENESS
+				printf ("\tKILL: R%d(%d)\n", ins->dreg, idx);
+#endif
+				update_live_range2 (&vars [idx], abs_pos + inst_num + 1); 
+				mono_bitset_set_fast (bb->kill_set, idx);
+				vi->spill_costs += SPILL_COST_INCREMENT;
+			}
+		}
+	}
+}
+
 /* generic liveness analysis code. CFG specific parts are 
  * in update_gen_kill_set()
  */
@@ -260,7 +395,6 @@ mono_analyze_liveness (MonoCompile *cfg)
 	MonoBasicBlock **worklist;
 	guint32 l_end;
 	int bitsize;
-	guint8 *mem;
 
 #ifdef DEBUG_LIVENESS
 	printf ("LIVENESS %s\n", mono_method_full_name (cfg->method, TRUE));
@@ -274,20 +408,7 @@ mono_analyze_liveness (MonoCompile *cfg)
 		return;
 
 	bitsize = mono_bitset_alloc_size (max_vars, 0);
-	mem = mono_mempool_alloc0 (cfg->mempool, cfg->num_bblocks * bitsize * 4);
 
-	for (i = 0; i < cfg->num_bblocks; ++i) {
-		MonoBasicBlock *bb = cfg->bblocks [i];
-
-		bb->gen_set = mono_bitset_mem_new (mem, max_vars, MONO_BITSET_DONT_FREE);
-		mem += bitsize;
-		bb->kill_set = mono_bitset_mem_new (mem, max_vars, MONO_BITSET_DONT_FREE);
-		mem += bitsize;
-		/* Initialized later */
-		bb->live_in_set = NULL;
-		bb->live_out_set = mono_bitset_mem_new (mem, max_vars, MONO_BITSET_DONT_FREE);
-		mem += bitsize;
-	}
 	for (i = 0; i < max_vars; i ++) {
 		MONO_VARINFO (cfg, i)->range.first_use.abs_pos = ~ 0;
 		MONO_VARINFO (cfg, i)->range.last_use .abs_pos =   0;
@@ -299,14 +420,23 @@ mono_analyze_liveness (MonoCompile *cfg)
 		MonoInst *inst;
 		int tree_num;
 
-		if (cfg->aliasing_info != NULL)
-			mono_aliasing_initialize_code_traversal (cfg->aliasing_info, bb);
-		
-		for (tree_num = 0, inst = bb->code; inst; inst = inst->next, tree_num++) {
+		bb->gen_set = mono_bitset_mp_new (cfg->mempool, bitsize, max_vars);
+		bb->kill_set = mono_bitset_mp_new (cfg->mempool, bitsize, max_vars);
+
+		if (cfg->new_ir) {
+			analyze_liveness_bb (cfg, bb);
+		} else {
+			if (cfg->aliasing_info != NULL)
+				mono_aliasing_initialize_code_traversal (cfg->aliasing_info, bb);
+
+			tree_num = 0;
+			MONO_BB_FOR_EACH_INS (bb, inst) {
 #ifdef DEBUG_LIVENESS
-			mono_print_tree (inst); printf ("\n");
+				mono_print_tree (inst); printf ("\n");
 #endif
-			update_gen_kill_set (cfg, bb, inst, tree_num);
+				update_gen_kill_set (cfg, bb, inst, tree_num);
+				tree_num ++;
+			}
 		}
 
 #ifdef DEBUG_LIVENESS
@@ -335,6 +465,10 @@ mono_analyze_liveness (MonoCompile *cfg)
 
 		worklist [l_end ++] = bb;
 		in_worklist [bb->dfn] = TRUE;
+
+		/* Initialized later */
+		bb->live_in_set = NULL;
+		bb->live_out_set = mono_bitset_mp_new (cfg->mempool, bitsize, max_vars);
 	}
 
 	out_iter = 0;
@@ -356,6 +490,7 @@ mono_analyze_liveness (MonoCompile *cfg)
 		printf ("\n");
 #endif
 
+
 		if (bb->out_count == 0)
 			continue;
 
@@ -367,32 +502,29 @@ mono_analyze_liveness (MonoCompile *cfg)
 		}
 		else {
 			changed = FALSE;
-			mono_bitset_copyto (bb->live_out_set, old_live_out_set);
+			mono_bitset_copyto_fast (bb->live_out_set, old_live_out_set);
 		}
  
 		for (j = 0; j < bb->out_count; j++) {
 			out_bb = bb->out_bb [j];
 
 			if (!out_bb->live_in_set) {
-				out_bb->live_in_set = mono_bitset_mem_new (mem, max_vars, MONO_BITSET_DONT_FREE);
-				mem += bitsize;
+				out_bb->live_in_set = mono_bitset_mp_new_noinit (cfg->mempool, bitsize, max_vars);
 
-				mono_bitset_copyto (out_bb->live_out_set, out_bb->live_in_set);
-				mono_bitset_sub (out_bb->live_in_set, out_bb->kill_set);
-				mono_bitset_union (out_bb->live_in_set, out_bb->gen_set);
+				mono_bitset_copyto_fast (out_bb->live_out_set, out_bb->live_in_set);
+				mono_bitset_sub_fast (out_bb->live_in_set, out_bb->kill_set);
+				mono_bitset_union_fast (out_bb->live_in_set, out_bb->gen_set);
 			}
 
-			mono_bitset_union (bb->live_out_set, out_bb->live_in_set);
+			mono_bitset_union_fast (bb->live_out_set, out_bb->live_in_set);
 		}
 				
 		if (changed || !mono_bitset_equal (old_live_out_set, bb->live_out_set)) {
-			if (!bb->live_in_set) {
-				bb->live_in_set = mono_bitset_mem_new (mem, max_vars, MONO_BITSET_DONT_FREE);
-				mem += bitsize;
-			}
-			mono_bitset_copyto (bb->live_out_set, bb->live_in_set);
-			mono_bitset_sub (bb->live_in_set, bb->kill_set);
-			mono_bitset_union (bb->live_in_set, bb->gen_set);
+			if (!bb->live_in_set)
+				bb->live_in_set = mono_bitset_mp_new_noinit (cfg->mempool, bitsize, max_vars);
+			mono_bitset_copyto_fast (bb->live_out_set, bb->live_in_set);
+			mono_bitset_sub_fast (bb->live_in_set, bb->kill_set);
+			mono_bitset_union_fast (bb->live_in_set, bb->gen_set);
 
 			for (j = 0; j < bb->in_count; j++) {
 				MonoBasicBlock *in_bb = bb->in_bb [j];
@@ -415,7 +547,9 @@ mono_analyze_liveness (MonoCompile *cfg)
 		}
 	}
 
-	//printf ("IT: %d %d %d.\n", iterations, in_iter, out_iter);
+#ifdef DEBUG_LIVENESS
+		printf ("IT: %d %d.\n", cfg->num_bblocks, out_iter);
+#endif
 
 	mono_bitset_free (old_live_out_set);
 
@@ -427,22 +561,19 @@ mono_analyze_liveness (MonoCompile *cfg)
 		MonoBasicBlock *bb = cfg->bblocks [i];
 
 		if (!bb->live_in_set) {
-			bb->live_in_set = mono_bitset_mem_new (mem, max_vars, MONO_BITSET_DONT_FREE);
-			mem += bitsize;
+			bb->live_in_set = mono_bitset_mp_new (cfg->mempool, bitsize, max_vars);
 
-			mono_bitset_copyto (bb->live_out_set, bb->live_in_set);
-			mono_bitset_sub (bb->live_in_set, bb->kill_set);
-			mono_bitset_union (bb->live_in_set, bb->gen_set);
+			mono_bitset_copyto_fast (bb->live_out_set, bb->live_in_set);
+			mono_bitset_sub_fast (bb->live_in_set, bb->kill_set);
+			mono_bitset_union_fast (bb->live_in_set, bb->gen_set);
 		}
 	}
 
-	/*
-	 * This code can be slow for large methods so inline the calls to
-	 * mono_bitset_test.
-	 */
 	for (i = 0; i < cfg->num_bblocks; ++i) {
 		MonoBasicBlock *bb = cfg->bblocks [i];
 		guint32 rem, max;
+		guint32 abs_pos = (bb->dfn << 16);
+		MonoMethodVar *vars = cfg->vars;
 
 		if (!bb->live_out_set)
 			continue;
@@ -452,22 +583,17 @@ mono_analyze_liveness (MonoCompile *cfg)
 		for (j = 0; j < max; ++j) {
 			gsize bits_in;
 			gsize bits_out;
-			int k, end;
+			int k;
 
 			bits_in = mono_bitset_get_fast (bb->live_in_set, j);
 			bits_out = mono_bitset_get_fast (bb->live_out_set, j);
 
-			if (j == max)
-				end = (j * BITS_PER_CHUNK) + rem;
-			else
-				end = (j * BITS_PER_CHUNK) + BITS_PER_CHUNK;
-
 			k = (j * BITS_PER_CHUNK);
 			while ((bits_in || bits_out)) {
 				if (bits_in & 1)
-					update_live_range (cfg, k, bb->dfn, 0);
+					update_live_range2 (&vars [k], abs_pos + 0);
 				if (bits_out & 1)
-					update_live_range (cfg, k, bb->dfn, 0xffff);
+					update_live_range2 (&vars [k], abs_pos + 0xffff);
 				bits_in >>= 1;
 				bits_out >>= 1;
 				k ++;
@@ -475,15 +601,6 @@ mono_analyze_liveness (MonoCompile *cfg)
 		}
 	}
 
-	/* todo: remove code when we have verified that the liveness for try/catch blocks
-	 * works perfectly 
-	 */
-	/* 
-	 * Currently, this can't be commented out since exception blocks are not
-	 * processed during liveness analysis.
-	 */
-	handle_exception_clauses (cfg);
-
 	/*
 	 * Arguments need to have their live ranges extended to the beginning of
 	 * the method to account for the arg reg/memory -> global register copies
@@ -492,8 +609,11 @@ mono_analyze_liveness (MonoCompile *cfg)
 
 	for (i = 0; i < max_vars; i ++) {
 		MonoMethodVar *vi = MONO_VARINFO (cfg, i);
-		if (cfg->varinfo [vi->idx]->opcode == OP_ARG)
+		if (cfg->varinfo [vi->idx]->opcode == OP_ARG) {
+			if (vi->range.last_use.abs_pos == 0 && !(cfg->varinfo [vi->idx]->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
+				cfg->varinfo [vi->idx]->flags |= MONO_INST_IS_DEAD;
 			vi->range.first_use.abs_pos = 0;
+		}
 	}
 
 #ifdef DEBUG_LIVENESS
@@ -506,4 +626,480 @@ mono_analyze_liveness (MonoCompile *cfg)
 		mono_bitset_print (bb->live_out_set); 
 	}
 #endif
+
+	if (cfg->new_ir) {
+		if (!cfg->disable_initlocals_opt)
+			optimize_initlocals2 (cfg);
+
+#ifdef ENABLE_LIVENESS2
+		/* This improves code size by about 5% but slows down compilation too much */
+		/* FIXME: This crashes when compiling 2.0 mscorlib */
+		if (FALSE && cfg->compile_aot)
+			mono_analyze_liveness2 (cfg);
+#endif
+	}
+	else {
+		if (!cfg->disable_initlocals_opt)
+			optimize_initlocals (cfg);
+	}
+}
+
+/**
+ * optimize_initlocals:
+ *
+ * Try to optimize away some of the redundant initialization code inserted because of
+ * 'locals init' using the liveness information.
+ */
+static void
+optimize_initlocals2 (MonoCompile *cfg)
+{
+	MonoBitSet *used;
+	MonoInst *ins;
+	MonoBasicBlock *initlocals_bb;
+
+	used = mono_bitset_new (cfg->next_vreg + 1, 0);
+
+	mono_bitset_clear_all (used);
+	initlocals_bb = cfg->bb_entry->next_bb;
+	for (ins = initlocals_bb->code; ins; ins = ins->next) {
+		const char *spec = INS_INFO (ins->opcode);
+
+		if (spec [MONO_INST_SRC1] != ' ')
+			mono_bitset_set_fast (used, ins->sreg1);
+		if (spec [MONO_INST_SRC2] != ' ')
+			mono_bitset_set_fast (used, ins->sreg2);
+		if (MONO_IS_STORE_MEMBASE (ins))
+			mono_bitset_set_fast (used, ins->dreg);
+	}
+
+	for (ins = initlocals_bb->code; ins; ins = ins->next) {
+		const char *spec = INS_INFO (ins->opcode);
+
+		/* Look for statements whose dest is not used in this bblock and not live on exit. */
+		if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
+			MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
+
+			if (var && !mono_bitset_test_fast (used, ins->dreg) && !mono_bitset_test_fast (initlocals_bb->live_out_set, var->inst_c0) && (var != cfg->ret) && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
+				//printf ("DEAD: "); mono_print_ins (ins);
+				if ((ins->opcode == OP_ICONST) || (ins->opcode == OP_I8CONST) || (ins->opcode == OP_R8CONST)) {
+					NULLIFY_INS (ins);
+					MONO_VARINFO (cfg, var->inst_c0)->spill_costs -= 1;
+					/* 
+					 * We should shorten the liveness interval of these vars as well, but
+					 * don't have enough info to do that.
+					 */
+				}
+			}
+		}
+	}
+
+	g_free (used);
+}
+
+void
+mono_linterval_add_range (MonoCompile *cfg, MonoLiveInterval *interval, int from, int to)
+{
+	MonoLiveRange2 *prev_range, *next_range, *new_range;
+
+	g_assert (to >= from);
+
+	/* Optimize for extending the first interval backwards */
+	if (G_LIKELY (interval->range && (interval->range->from > from) && (interval->range->from == to))) {
+		interval->range->from = from;
+		return;
+	}
+
+	/* Find a place in the list for the new range */
+	prev_range = NULL;
+	next_range = interval->range;
+	while ((next_range != NULL) && (next_range->from <= from)) {
+		prev_range = next_range;
+		next_range = next_range->next;
+	}
+
+	if (prev_range && prev_range->to == from) {
+		/* Merge with previous */
+		prev_range->to = to;
+	} else if (next_range && next_range->from == to) {
+		/* Merge with previous */
+		next_range->from = from;
+	} else {
+		/* Insert it */
+		new_range = mono_mempool_alloc (cfg->mempool, sizeof (MonoLiveRange2));
+		new_range->from = from;
+		new_range->to = to;
+		new_range->next = NULL;
+
+		if (prev_range)
+			prev_range->next = new_range;
+		else
+			interval->range = new_range;
+		if (next_range)
+			new_range->next = next_range;
+		else
+			interval->last_range = new_range;
+	}
+
+	/* FIXME: Merge intersecting ranges */
+}
+
+void
+mono_linterval_print (MonoLiveInterval *interval)
+{
+	MonoLiveRange2 *range;
+
+	for (range = interval->range; range != NULL; range = range->next)
+		printf ("[%x-%x] ", range->from, range->to);
+}
+
+void
+mono_linterval_print_nl (MonoLiveInterval *interval)
+{
+	mono_linterval_print (interval);
+	printf ("\n");
+}
+
+/**
+ * mono_linterval_convers:
+ *
+ *   Return whenever INTERVAL covers the position POS.
+ */
+gboolean
+mono_linterval_covers (MonoLiveInterval *interval, int pos)
+{
+	MonoLiveRange2 *range;
+
+	for (range = interval->range; range != NULL; range = range->next) {
+		if (pos >= range->from && pos <= range->to)
+			return TRUE;
+		if (range->from > pos)
+			return FALSE;
+	}
+
+	return FALSE;
+}
+
+/**
+ * mono_linterval_get_intersect_pos:
+ *
+ *   Determine whenever I1 and I2 intersect, and if they do, return the first
+ * point of intersection. Otherwise, return -1.
+ */
+gint32
+mono_linterval_get_intersect_pos (MonoLiveInterval *i1, MonoLiveInterval *i2)
+{
+	MonoLiveRange2 *r1, *r2;
+
+	/* FIXME: Optimize this */
+	for (r1 = i1->range; r1 != NULL; r1 = r1->next) {
+		for (r2 = i2->range; r2 != NULL; r2 = r2->next) {
+			if (r2->to > r1->from && r2->from < r1->to) {
+				if (r2->from <= r1->from)
+					return r1->from;
+				else
+					return r2->from;
+			}
+		}
+	}
+
+	return -1;
+}
+ 
+/**
+ * mono_linterval_split
+ *
+ *   Split L at POS and store the newly created intervals into L1 and L2. POS becomes
+ * part of L2.
+ */
+void
+mono_linterval_split (MonoCompile *cfg, MonoLiveInterval *interval, MonoLiveInterval **i1, MonoLiveInterval **i2, int pos)
+{
+	MonoLiveRange2 *r;
+
+	g_assert (pos > interval->range->from && pos <= interval->last_range->to);
+
+	*i1 = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoLiveInterval));
+	*i2 = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoLiveInterval));
+
+	for (r = interval->range; r; r = r->next) {
+		if (pos > r->to) {
+			/* Add it to the first child */
+			mono_linterval_add_range (cfg, *i1, r->from, r->to);
+		} else if (pos > r->from && pos <= r->to) {
+			/* Split at pos */
+			mono_linterval_add_range (cfg, *i1, r->from, pos - 1);
+			mono_linterval_add_range (cfg, *i2, pos, r->to);
+		} else {
+			/* Add it to the second child */
+			mono_linterval_add_range (cfg, *i2, r->from, r->to);
+		}
+	}
+}
+
+#ifdef ENABLE_LIVENESS2
+
+#if 0
+#define LIVENESS_DEBUG(a) do { a; } while (0)
+#else
+#define LIVENESS_DEBUG(a)
+#endif
+
+static inline void
+update_liveness2 (MonoCompile *cfg, MonoInst *ins, gboolean set_volatile, int inst_num, gint32 *last_use)
+{
+	const char *spec = INS_INFO (ins->opcode);
+	int sreg;
+
+	LIVENESS_DEBUG (printf ("\t%x: ", inst_num); mono_print_ins (ins));
+
+	if (ins->opcode == OP_NOP)
+		return;
+
+	/* DREG */
+	if ((spec [MONO_INST_DEST] != ' ') && get_vreg_to_inst (cfg, ins->dreg)) {
+		MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
+		int idx = var->inst_c0;
+		MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
+
+		if (MONO_IS_STORE_MEMBASE (ins)) {
+			if (last_use [idx] == 0) {
+				LIVENESS_DEBUG (printf ("\tlast use of R%d set to %x\n", ins->dreg, inst_num));
+				last_use [idx] = inst_num;
+			}
+		} else {
+			if (last_use [idx] > 0) {
+				LIVENESS_DEBUG (printf ("\tadd range to R%d: [%x, %x)\n", ins->dreg, inst_num, last_use [idx]));
+				mono_linterval_add_range (cfg, vi->interval, inst_num, last_use [idx]);
+				last_use [idx] = 0;
+			}
+			else {
+				/* Try dead code elimination */
+				if ((var != cfg->ret) && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)) && ((ins->opcode == OP_ICONST) || (ins->opcode == OP_I8CONST) || (ins->opcode == OP_R8CONST)) && !(var->flags & MONO_INST_VOLATILE)) {
+					LIVENESS_DEBUG (printf ("\tdead def of R%d, eliminated\n", ins->dreg));
+					ins->opcode = OP_NOP;
+					ins->dreg = ins->sreg1 = ins->sreg2 = -1;
+					return;
+				}
+
+				LIVENESS_DEBUG (printf ("\tdead def of R%d, add range to R%d: [%x, %x]\n", ins->dreg, ins->dreg, inst_num, inst_num + 1));
+				mono_linterval_add_range (cfg, vi->interval, inst_num, inst_num + 1);
+			}
+		}
+	}
+
+	/* SREG1 */
+	sreg = ins->sreg1;
+	if ((spec [MONO_INST_SRC1] != ' ') && get_vreg_to_inst (cfg, sreg)) {
+		MonoInst *var = get_vreg_to_inst (cfg, sreg);
+		int idx = var->inst_c0;
+
+		if (last_use [idx] == 0) {
+			LIVENESS_DEBUG (printf ("\tlast use of R%d set to %x\n", sreg, inst_num));
+			last_use [idx] = inst_num;
+		}
+	}
+
+	/* SREG2 */
+	sreg = ins->sreg2;
+	if ((spec [MONO_INST_SRC2] != ' ') && get_vreg_to_inst (cfg, sreg)) {
+		MonoInst *var = get_vreg_to_inst (cfg, sreg);
+		int idx = var->inst_c0;
+
+		if (last_use [idx] == 0) {
+			LIVENESS_DEBUG (printf ("\tlast use of R%d set to %x\n", sreg, inst_num));
+			last_use [idx] = inst_num;
+		}
+	}
 }
+
+static void
+mono_analyze_liveness2 (MonoCompile *cfg)
+{
+	int bnum, idx, i, j, nins, rem, max, max_vars, block_from, block_to, pos, reverse_len;
+	gint32 *last_use;
+	static guint32 disabled = -1;
+	MonoInst **reverse;
+
+	if (disabled == -1)
+		disabled = getenv ("DISABLED") != NULL;
+
+	if (disabled)
+		return;
+
+	LIVENESS_DEBUG (printf ("LIVENESS 2 %s\n", mono_method_full_name (cfg->method, TRUE)));
+
+	/*
+	if (strstr (cfg->method->name, "test_") != cfg->method->name)
+		return;
+	*/
+
+	max_vars = cfg->num_varinfo;
+	last_use = g_new0 (gint32, max_vars);
+
+	reverse_len = 1024;
+	reverse = mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * reverse_len);
+
+	for (idx = 0; idx < max_vars; ++idx) {
+		MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
+
+		vi->interval = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoLiveInterval));
+	}
+
+	/*
+	 * Process bblocks in reverse order, so the addition of new live ranges
+	 * to the intervals is faster.
+	 */
+	for (bnum = cfg->num_bblocks - 1; bnum >= 0; --bnum) {
+		MonoBasicBlock *bb = cfg->bblocks [bnum];
+		MonoInst *ins;
+
+		block_from = (bb->dfn << 16) + 1; /* so pos > 0 */
+		if (bnum < cfg->num_bblocks - 1)
+			/* Beginning of the next bblock */
+			block_to = (cfg->bblocks [bnum + 1]->dfn << 16) + 1;
+		else
+			block_to = (bb->dfn << 16) + 0xffff;
+
+		LIVENESS_DEBUG (printf ("LIVENESS BLOCK BB%d:\n", bb->block_num));
+
+		memset (last_use, 0, max_vars * sizeof (gint32));
+		
+		/* For variables in bb->live_out, set last_use to block_to */
+
+		rem = max_vars % BITS_PER_CHUNK;
+		max = ((max_vars + (BITS_PER_CHUNK -1)) / BITS_PER_CHUNK);
+		for (j = 0; j < max; ++j) {
+			gsize bits_out;
+			int k;
+
+			bits_out = mono_bitset_get_fast (bb->live_out_set, j);
+			k = (j * BITS_PER_CHUNK);	
+			while (bits_out) {
+				if (bits_out & 1) {
+					LIVENESS_DEBUG (printf ("Var R%d live at exit, set last_use to %x\n", cfg->varinfo [k]->dreg, block_to));
+					last_use [k] = block_to;
+				}
+				bits_out >>= 1;
+				k ++;
+			}
+		}
+
+		if (cfg->ret)
+			last_use [cfg->ret->inst_c0] = block_to;
+
+		for (nins = 0, pos = block_from, ins = bb->code; ins; ins = ins->next, ++nins, ++pos) {
+			if (nins >= reverse_len) {
+				int new_reverse_len = reverse_len * 2;
+				MonoInst **new_reverse = mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * new_reverse_len);
+				memcpy (new_reverse, reverse, sizeof (MonoInst*) * reverse_len);
+				reverse = new_reverse;
+				reverse_len = new_reverse_len;
+			}
+
+			reverse [nins] = ins;
+		}
+
+		/* Process instructions backwards */
+		for (i = nins - 1; i >= 0; --i) {
+			MonoInst *ins = (MonoInst*)reverse [i];
+
+ 			update_liveness2 (cfg, ins, FALSE, pos, last_use);
+
+			pos --;
+		}
+
+		for (idx = 0; idx < max_vars; ++idx) {
+			MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
+
+			if (last_use [idx] != 0) {
+				/* Live at exit, not written -> live on enter */
+				LIVENESS_DEBUG (printf ("Var R%d live at enter, add range to R%d: [%x, %x)\n", cfg->varinfo [idx]->dreg, cfg->varinfo [idx]->dreg, block_from, last_use [idx]));
+				mono_linterval_add_range (cfg, vi->interval, block_from, last_use [idx]);
+			}
+		}
+	}
+
+	/*
+	 * Arguments need to have their live ranges extended to the beginning of
+	 * the method to account for the arg reg/memory -> global register copies
+	 * in the prolog (bug #74992).
+	 */
+	for (i = 0; i < max_vars; i ++) {
+		MonoMethodVar *vi = MONO_VARINFO (cfg, i);
+		if (cfg->varinfo [vi->idx]->opcode == OP_ARG)
+			mono_linterval_add_range (cfg, vi->interval, 0, 1);
+	}
+
+#if 0
+	for (idx = 0; idx < max_vars; ++idx) {
+		MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
+		
+		LIVENESS_DEBUG (printf ("LIVENESS R%d: ", cfg->varinfo [idx]->dreg));
+		LIVENESS_DEBUG (mono_linterval_print (vi->interval));
+		LIVENESS_DEBUG (printf ("\n"));
+	}
+#endif
+
+	g_free (last_use);
+}
+
+#endif
+
+static void
+update_used (MonoCompile *cfg, MonoInst *inst, MonoBitSet *used)
+{
+	int arity = mono_burg_arity [inst->opcode];
+
+	if (arity)
+		update_used (cfg, inst->inst_i0, used);
+
+	if (arity > 1)
+		update_used (cfg, inst->inst_i1, used);
+
+	if (inst->ssa_op & MONO_SSA_LOAD_STORE) {
+		if (inst->ssa_op == MONO_SSA_LOAD) {
+			int idx = inst->inst_i0->inst_c0;
+
+			mono_bitset_set_fast (used, idx);
+		}
+	}
+} 
+
+/**
+ * optimize_initlocals:
+ *
+ * Try to optimize away some of the redundant initialization code inserted because of
+ * 'locals init' using the liveness information.
+ */
+static void
+optimize_initlocals (MonoCompile *cfg)
+{
+	MonoBitSet *used;
+	MonoInst *ins;
+	MonoBasicBlock *initlocals_bb;
+
+	used = mono_bitset_new (cfg->num_varinfo, 0);
+
+	mono_bitset_clear_all (used);
+	initlocals_bb = cfg->bb_entry->next_bb;
+	MONO_BB_FOR_EACH_INS (initlocals_bb, ins)
+		update_used (cfg, ins, used);
+
+	MONO_BB_FOR_EACH_INS (initlocals_bb, ins) {
+		if (ins->ssa_op == MONO_SSA_STORE) {
+			int idx = ins->inst_i0->inst_c0;
+			MonoInst *var = cfg->varinfo [idx];
+
+			if (var && !mono_bitset_test_fast (used, idx) && !mono_bitset_test_fast (initlocals_bb->live_out_set, var->inst_c0) && (var != cfg->ret) && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
+				if (ins->inst_i1 && ((ins->inst_i1->opcode == OP_ICONST) || (ins->inst_i1->opcode == OP_I8CONST))) {
+					NULLIFY_INS (ins);
+					ins->ssa_op = MONO_SSA_NOP;
+					MONO_VARINFO (cfg, var->inst_c0)->spill_costs -= 1;					
+				}
+			}
+		}
+	}
+
+	g_free (used);
+}
+