X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Fbe%2Fbeverify.c;h=7cf0047d1f7a2b719e39be25ffe9b50f8800e9b1;hb=e50e639452115e58f2d9313ebc44d0296d3adfa2;hp=3b3b153bfc5a56fa8d9cb1134cdc8b4bbd0775e5;hpb=eb285d9224370de02302b8191132928add5a3318;p=libfirm

diff --git a/ir/be/beverify.c b/ir/be/beverify.c
index 3b3b153bf..7cf0047d1 100644
--- a/ir/be/beverify.c
+++ b/ir/be/beverify.c
@@ -1,196 +1,853 @@
 /*
- * Author:    Matthias Braun
- * Date:      05.05.2006
- * Copyright: (c) Universitaet Karlsruhe
- * License:   This file protected by GPL -  GNU GENERAL PUBLIC LICENSE.
- * CVS-Id:    $Id$
+ * This file is part of libFirm.
+ * Copyright (C) 2012 University of Karlsruhe.
+ */
+
+/**
+ * @file
+ * @brief       Various verify routines that check a scheduled graph for correctness.
+ * @author      Matthias Braun
+ * @date        05.05.2006
  */
-#ifdef HAVE_CONFIG_H
 #include "config.h"
-#endif
 
-#include "beverify.h"
-#include "belive.h"
-#include "besched.h"
+#include <limits.h>
+#include <stdbool.h>
+
+#include "bitset.h"
+#include "set.h"
+#include "array.h"
 
 #include "irnode.h"
 #include "irgraph.h"
 #include "irgwalk.h"
 #include "irprintf.h"
 #include "irdump_t.h"
+#include "iredges.h"
+
+#include "beverify.h"
+#include "belive.h"
+#include "besched.h"
+#include "benode.h"
+#include "beirg.h"
+#include "beintlive_t.h"
+#include "belistsched.h"
+
+static bool my_values_interfere(const ir_node *a, const ir_node *b);
 
 typedef struct be_verify_register_pressure_env_t_ {
 	ir_graph                    *irg;                 /**< the irg to verify */
-	const arch_env_t            *arch_env;            /**< an architecture environment */
+	be_lv_t                     *lv;                  /**< Liveness information. */
 	const arch_register_class_t *cls;                 /**< the register class to check for */
-	int                         registers_available;  /**< number of available registers */
-	int                         problem_found;        /**< flag indicating if a problem was found */
+	unsigned                    registers_available;  /**< number of available registers */
+	bool                        problem_found;        /**< flag indicating if a problem was found */
 } be_verify_register_pressure_env_t;
 
 /**
  * Print all nodes of a pset into a file.
  */
-static void print_living_values(FILE *F, pset *live_nodes)
+static void print_living_values(FILE *F, const ir_nodeset_t *live_nodes)
 {
-	ir_node *node;
-
 	ir_fprintf(F, "\t");
-	foreach_pset(live_nodes, node) {
+	foreach_ir_nodeset(live_nodes, node, iter) {
 		ir_fprintf(F, "%+F ", node);
 	}
 	ir_fprintf(F, "\n");
 }
 
+static const char *get_irg_name(ir_graph *irg)
+{
+	ir_entity *entity = get_irg_entity(irg);
+	return get_entity_ld_name(entity);
+}
+
 /**
  * Check if number of live nodes never exceeds the number of available registers.
  */
 static void verify_liveness_walker(ir_node *block, void *data)
 {
 	be_verify_register_pressure_env_t *env = (be_verify_register_pressure_env_t *)data;
-	pset    *live_nodes = pset_new_ptr_default();
-	ir_node *irn;
-	int pressure;
+	ir_nodeset_t live_nodes;
 
 	/* collect register pressure info, start with end of a block */
-	be_liveness_end_of_block(env->arch_env, env->cls, block, live_nodes);
+	ir_nodeset_init(&live_nodes);
+	be_liveness_end_of_block(env->lv, env->cls, block,
+	                         &live_nodes);
 
-	pressure = pset_count(live_nodes);
-	if(pressure > env->registers_available) {
+	unsigned pressure = ir_nodeset_size(&live_nodes);
+	if (pressure > env->registers_available) {
 		ir_fprintf(stderr, "Verify Warning: Register pressure too high at end of block %+F(%s) (%d/%d):\n",
-			block, get_irg_dump_name(env->irg), pressure, env->registers_available);
-		print_living_values(stderr, live_nodes);
-		env->problem_found = 1;
+			block, get_irg_name(env->irg), pressure, env->registers_available);
+		print_living_values(stderr, &live_nodes);
+		env->problem_found = true;
 	}
 
 	sched_foreach_reverse(block, irn) {
 		if (is_Phi(irn))
 			break;
 
-		be_liveness_transfer(env->arch_env, env->cls, irn, live_nodes);
+		// print_living_values(stderr, &live_nodes);
+		be_liveness_transfer(env->cls, irn, &live_nodes);
 
-		pressure = pset_count(live_nodes);
+		pressure = ir_nodeset_size(&live_nodes);
 
-		if(pressure > env->registers_available) {
+		if (pressure > env->registers_available) {
 			ir_fprintf(stderr, "Verify Warning: Register pressure too high before node %+F in %+F(%s) (%d/%d):\n",
-				irn, block, get_irg_dump_name(env->irg), pressure, env->registers_available);
-			print_living_values(stderr, live_nodes);
-			env->problem_found = 1;
+				irn, block, get_irg_name(env->irg), pressure, env->registers_available);
+			print_living_values(stderr, &live_nodes);
+			env->problem_found = true;
+			assert(0);
 		}
 	}
-	del_pset(live_nodes);
+	ir_nodeset_destroy(&live_nodes);
 }
 
-/**
- * Start a walk over the irg and check the register pressure.
- */
-int be_verify_register_pressure(const arch_env_t *arch_env, const arch_register_class_t *cls, ir_graph *irg)
+bool be_verify_register_pressure(ir_graph *irg, const arch_register_class_t *cls)
 {
 	be_verify_register_pressure_env_t env;
 
-	be_liveness(irg);
-
+	env.lv                  = be_liveness_new(irg);
 	env.irg                 = irg;
-	env.arch_env            = arch_env;
 	env.cls                 = cls;
-	env.registers_available = arch_count_non_ignore_regs(arch_env, cls);
-	env.problem_found       = 0;
+	env.registers_available = be_get_n_allocatable_regs(irg, cls);
+	env.problem_found       = false;
 
+	be_liveness_compute_sets(env.lv);
 	irg_block_walk_graph(irg, verify_liveness_walker, NULL, &env);
+	be_liveness_free(env.lv);
 
 	return ! env.problem_found;
 }
 
+/*--------------------------------------------------------------------------- */
+
 typedef struct be_verify_schedule_env_t_ {
-	int      problem_found;    /**< flags indicating if there was a problem */
-	ir_graph *irg;             /**< the irg to check */
+	bool      problem_found; /**< flags indicating a problem */
+	bitset_t *scheduled;     /**< bitset of scheduled nodes */
+	ir_graph *irg;           /**< the irg to check */
 } be_verify_schedule_env_t;
 
-/**
- * Simple schedule checker.
- */
 static void verify_schedule_walker(ir_node *block, void *data)
 {
 	be_verify_schedule_env_t *env = (be_verify_schedule_env_t*) data;
-	ir_node *node;
-	int non_phi_found  = 0;
-	int cfchange_found = 0;
-	// TODO ask arch about delay branches
-	int delay_branches = 0;
-	pset *uses = pset_new_ptr_default();
+	ir_node *non_phi_found  = NULL;
+	ir_node *cfchange_found = NULL;
+	int last_timestep = INT_MIN;
 
 	/*
 	 * Tests for the following things:
-	 *   1. Make sure that all phi nodes are scheduled at the beginning of the block
-	 *   2. There is 1 or no control flow changing node scheduled and exactly delay_branches operations after it.
-	 *   3. No value is defined after it has been used
+	 *   1. Make sure that all phi nodes are scheduled at the beginning of the
+	 *      block
+	 *   2. No value is defined after it has been used
+	 *   3. mode_T nodes have all projs scheduled behind them followed by Keeps
+	 *       (except mode_X projs)
 	 */
 	sched_foreach(block, node) {
-		int i, arity;
+		/* this node is scheduled */
+		if (bitset_is_set(env->scheduled, get_irn_idx(node))) {
+			ir_fprintf(stderr, "Verify warning: %+F appears to be schedule twice\n");
+			env->problem_found = true;
+		}
+		bitset_set(env->scheduled, get_irn_idx(node));
 
-		// 1. Check for phis
+		/* Check that scheduled nodes are in the correct block */
+		if (get_nodes_block(node) != block) {
+			ir_fprintf(stderr, "Verify warning: %+F is in block %+F but scheduled in %+F\n", node, get_nodes_block(node), block);
+			env->problem_found = true;
+		}
+
+		/* Check that timesteps are increasing */
+		int timestep = sched_get_time_step(node);
+		if (timestep <= last_timestep) {
+			ir_fprintf(stderr, "Verify warning: Schedule timestep did not increase at node %+F\n",
+			           node);
+			env->problem_found = true;
+		}
+		last_timestep = timestep;
+
+		if (arch_get_irn_flags(node) & arch_irn_flags_not_scheduled) {
+			ir_fprintf(stderr, "Verify warning: flags_not_scheduled node %+F scheduled anyway\n", node);
+			env->problem_found = true;
+		}
+
+		/* Check that phis come before any other node */
 		if (is_Phi(node)) {
-			if (non_phi_found) {
-				ir_fprintf(stderr, "Verify Warning: Phi node %+F scheduled after non-Phi nodes in block %+F (%s)\n",
-					node, block, get_irg_dump_name(env->irg));
-				env->problem_found = 1;
+			if (non_phi_found != NULL) {
+				ir_fprintf(stderr, "Verify Warning: Phi node %+F scheduled after non-Phi nodes (for example %+F) in block %+F (%s)\n",
+					node, non_phi_found, block, get_irg_name(env->irg));
+				env->problem_found = true;
 			}
 		} else {
-			non_phi_found = 1;
+			non_phi_found = node;
 		}
 
-		// 2. Check for control flow changing nodes
-		if (is_cfop(node) && get_irn_opcode(node) != iro_Start) {
+		/* Check for control flow changing nodes */
+		if (is_cfop(node)) {
 			/* check, that only one CF operation is scheduled */
-			if (cfchange_found == 1) {
-				ir_fprintf(stderr, "Verify Warning: More than 1 control flow changing node (%+F) scheduled in block %+F (%s)\n",
-					node, block, get_irg_dump_name(env->irg));
-				env->problem_found = 1;
-			}
-			cfchange_found = 1;
-		} else if (cfchange_found) {
-			/* check for delay branches */
-			if (delay_branches == 0) {
-				ir_fprintf(stderr, "Verify Warning: Node %+F scheduled after control flow changing node (+delay branches) in block %+F (%s)\n",
-					node, block, get_irg_dump_name(env->irg));
-				env->problem_found = 1;
+			if (cfchange_found != NULL) {
+				ir_fprintf(stderr, "Verify Warning: Additional control flow changing node %+F scheduled after %+F in block %+F (%s)\n",
+					node, block, cfchange_found, get_irg_name(env->irg));
+				env->problem_found = true;
 			} else {
-				delay_branches--;
+				cfchange_found = node;
+			}
+		} else if (cfchange_found != NULL) {
+			/* keepany isn't a real instruction. */
+			if (!be_is_Keep(node)) {
+				ir_fprintf(stderr, "Verify Warning: Node %+F scheduled after control flow changing node in block %+F (%s)\n",
+				           node, block, get_irg_name(env->irg));
+				env->problem_found = true;
 			}
 		}
 
-		// 3. Check for uses
-		if(pset_find_ptr(uses, node)) {
-			ir_fprintf(stderr, "Verify Warning: Value %+F used before it was defined in block %+F (%s)\n",
-				node, block, get_irg_dump_name(env->irg));
-			env->problem_found = 1;
+		/* Check that all uses come before their definitions */
+		if (!is_Phi(node)) {
+			sched_timestep_t nodetime = sched_get_time_step(node);
+			int              arity    = get_irn_arity(node);
+			for (int i = 0; i < arity; ++i) {
+				ir_node *arg = get_irn_n(node, i);
+				if (get_nodes_block(arg) != block || !sched_is_scheduled(arg))
+					continue;
+
+				if (sched_get_time_step(arg) >= nodetime) {
+					ir_fprintf(stderr, "Verify Warning: Value %+F used by %+F before it was defined in block %+F (%s)\n",
+					           arg, node, block, get_irg_name(env->irg));
+					env->problem_found = true;
+				}
+			}
+		}
+
+		/* Check that no dead nodes are scheduled */
+		if (get_irn_n_edges(node) == 0) {
+			ir_fprintf(stderr, "Verify warning: Node %+F is dead but scheduled in block %+F (%s)\n",
+			           node, block, get_irg_name(env->irg));
+			env->problem_found = true;
 		}
-		if(!is_Phi(node)) {
-			for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
-				pset_insert_ptr(uses, get_irn_n(node, i));
+
+		if (be_is_Keep(node) || be_is_CopyKeep(node)) {
+			/* at least 1 of the keep arguments has to be its schedule
+			 * predecessor */
+			ir_node *prev    = sched_prev(node);
+			while (be_is_Keep(prev) || be_is_CopyKeep(prev))
+				prev = sched_prev(prev);
+
+			int  arity = get_irn_arity(node);
+			bool found = false;
+			while (true) {
+				for (int i = 0; i < arity; ++i) {
+					ir_node *in = get_irn_n(node, i);
+					in = skip_Proj(in);
+					if (in == prev)
+						found = true;
+				}
+				if (found)
+					break;
+				prev = sched_prev(prev);
+				if (!is_Phi(prev))
+					break;
+			}
+			if (!found) {
+				ir_fprintf(stderr, "%+F not scheduled after its pred node in block %+F (%s)\n",
+				           node, block, get_irg_name(env->irg));
+				env->problem_found = true;
 			}
 		}
 	}
-	del_pset(uses);
+}
 
-	/* check that all delay branches are filled (at least with NOPs) */
-	if (cfchange_found && delay_branches != 0) {
-		ir_fprintf(stderr, "Not all delay slots filled after jump (%d/%d) in block %+F (%s)\n",
-			block, get_irg_dump_name(env->irg));
-		env->problem_found = 1;
+static void check_schedule(ir_node *node, void *data)
+{
+	be_verify_schedule_env_t *env = (be_verify_schedule_env_t*)data;
+	bool should_be = !is_Proj(node) && !(arch_get_irn_flags(node) & arch_irn_flags_not_scheduled);
+	bool scheduled = bitset_is_set(env->scheduled, get_irn_idx(node));
+
+	if (should_be != scheduled) {
+		ir_fprintf(stderr, "Verify warning: Node %+F in block %+F(%s) should%s be scheduled\n",
+			node, get_nodes_block(node), get_irg_name(env->irg), should_be ? "" : " not");
+		env->problem_found = true;
 	}
 }
 
-/**
- * Start a walk over the irg and check schedule.
- */
-int be_verify_schedule(ir_graph *irg)
+bool be_verify_schedule(ir_graph *irg)
 {
 	be_verify_schedule_env_t env;
 
-	env.problem_found = 0;
+	env.problem_found = false;
 	env.irg           = irg;
+	env.scheduled     = bitset_alloca(get_irg_last_idx(env.irg));
 
 	irg_block_walk_graph(irg, verify_schedule_walker, NULL, &env);
+	/* check if all nodes are scheduled */
+	irg_walk_graph(irg, check_schedule, NULL, &env);
 
 	return ! env.problem_found;
 }
+
+/*--------------------------------------------------------------------------- */
+
+typedef struct spill_t {
+	ir_node *spill;
+	ir_entity *ent;
+} spill_t;
+
+typedef struct {
+	ir_graph  *irg;
+	set       *spills;
+	ir_node  **reloads;
+	bool       problem_found;
+} be_verify_spillslots_env_t;
+
+static int cmp_spill(const void* d1, const void* d2, size_t size)
+{
+	(void) size;
+	const spill_t* s1 = (const spill_t*)d1;
+	const spill_t* s2 = (const spill_t*)d2;
+	return s1->spill != s2->spill;
+}
+
+static spill_t *find_spill(be_verify_spillslots_env_t *env, ir_node *node)
+{
+	spill_t spill;
+	spill.spill = node;
+	return set_find(spill_t, env->spills, &spill, sizeof(spill), hash_ptr(node));
+}
+
+static spill_t *get_spill(be_verify_spillslots_env_t *env, ir_node *node, ir_entity *ent)
+{
+	int hash = hash_ptr(node);
+	spill_t spill;
+	spill.spill = node;
+	spill_t *res = set_find(spill_t, env->spills, &spill, sizeof(spill), hash);
+
+	if (res == NULL) {
+		spill.ent = ent;
+		res = set_insert(spill_t, env->spills, &spill, sizeof(spill), hash);
+	}
+
+	return res;
+}
+
+static ir_node *get_memory_edge(const ir_node *node)
+{
+	ir_node *result = NULL;
+	int      arity  = get_irn_arity(node);
+	for (int i = arity - 1; i >= 0; --i) {
+		ir_node *arg = get_irn_n(node, i);
+		if (get_irn_mode(arg) == mode_M) {
+			assert(result == NULL);
+			result = arg;
+		}
+	}
+
+	return result;
+}
+
+static void collect(be_verify_spillslots_env_t *env, ir_node *node, ir_node *reload, ir_entity* ent);
+
+static void be_check_entity(be_verify_spillslots_env_t *env, ir_node *node, ir_entity *ent)
+{
+	if (ent == NULL) {
+		ir_fprintf(stderr, "Verify warning: Node %+F in block %+F(%s) should have an entity assigned\n",
+		           node, get_nodes_block(node), get_irg_name(env->irg));
+	}
+}
+
+static void collect_spill(be_verify_spillslots_env_t *env, ir_node *node, ir_node *reload, ir_entity* ent)
+{
+	ir_entity *spillent = arch_get_frame_entity(node);
+	be_check_entity(env, node, spillent);
+	get_spill(env, node, ent);
+
+	if (spillent != ent) {
+		ir_fprintf(stderr, "Verify warning: Spill %+F has different entity than reload %+F in block %+F(%s)\n",
+			node, reload, get_nodes_block(node), get_irg_name(env->irg));
+		env->problem_found = true;
+	}
+}
+
+static void collect_memperm(be_verify_spillslots_env_t *env, ir_node *node, ir_node *reload, ir_entity* ent)
+{
+	ir_node *memperm = get_Proj_pred(node);
+	int      out     = get_Proj_proj(node);
+
+	ir_entity *spillent = be_get_MemPerm_out_entity(memperm, out);
+	be_check_entity(env, memperm, spillent);
+	if (spillent != ent) {
+		ir_fprintf(stderr, "Verify warning: MemPerm %+F has different entity than reload %+F in block %+F(%s)\n",
+			node, reload, get_nodes_block(node), get_irg_name(env->irg));
+		env->problem_found = true;
+	}
+
+	int hash = hash_ptr(node);
+	spill_t spill;
+	spill.spill = node;
+	spill_t *res = set_find(spill_t, env->spills, &spill, sizeof(spill), hash);
+	if (res != NULL) {
+		return;
+	}
+
+	spill.ent = spillent;
+	(void)set_insert(spill_t, env->spills, &spill, sizeof(spill), hash);
+
+	int arity = be_get_MemPerm_entity_arity(memperm);
+	for (int i = 0; i < arity; ++i) {
+		ir_node* arg = get_irn_n(memperm, i + 1);
+		ir_entity* argent = be_get_MemPerm_in_entity(memperm, i);
+
+		collect(env, arg, memperm, argent);
+	}
+}
+
+static void collect_memphi(be_verify_spillslots_env_t *env, ir_node *node, ir_node *reload, ir_entity *ent)
+{
+	assert(is_Phi(node));
+
+	int hash = hash_ptr(node);
+	spill_t spill;
+	spill.spill = node;
+	spill_t *res = set_find(spill_t, env->spills, &spill, sizeof(spill), hash);
+	if (res != NULL) {
+		return;
+	}
+
+	spill.ent = ent;
+	(void)set_insert(spill_t, env->spills, &spill, sizeof(spill), hash);
+
+	/* is 1 of the arguments a spill? */
+	int arity = get_irn_arity(node);
+	for (int i = 0; i < arity; ++i) {
+		ir_node* arg = get_irn_n(node, i);
+		collect(env, arg, reload, ent);
+	}
+}
+
+static void collect(be_verify_spillslots_env_t *env, ir_node *node, ir_node *reload, ir_entity* ent)
+{
+	if (be_is_Spill(node)) {
+		collect_spill(env, node, reload, ent);
+	} else if (is_Proj(node)) {
+		collect_memperm(env, node, reload, ent);
+	} else if (is_Phi(node) && get_irn_mode(node) == mode_M) {
+		collect_memphi(env, node, reload, ent);
+	}
+}
+
+/**
+ * This walker function searches for reloads and collects all the spills
+ * and memphis attached to them.
+ */
+static void collect_spills_walker(ir_node *node, void *data)
+{
+	be_verify_spillslots_env_t *env = (be_verify_spillslots_env_t*)data;
+
+	if (be_is_Reload(node)) {
+		ir_node *spill = get_memory_edge(node);
+		if (spill == NULL) {
+			ir_fprintf(stderr, "Verify warning: No spill attached to reload %+F in block %+F(%s)\n",
+			           node, get_nodes_block(node), get_irg_name(env->irg));
+			env->problem_found = true;
+			return;
+		}
+		ir_entity *ent = arch_get_frame_entity(node);
+		be_check_entity(env, node, ent);
+
+		collect(env, spill, node, ent);
+		ARR_APP1(ir_node*, env->reloads, node);
+	}
+}
+
+static void check_spillslot_interference(be_verify_spillslots_env_t *env)
+{
+	int       spillcount = set_count(env->spills);
+	spill_t **spills     = ALLOCAN(spill_t*, spillcount);
+
+	int s = 0;
+	foreach_set(env->spills, spill_t, spill) {
+		spills[s++] = spill;
+	}
+	assert(s == spillcount);
+
+	for (int i = 0; i < spillcount; ++i) {
+		spill_t *sp1 = spills[i];
+
+		for (int i2 = i+1; i2 < spillcount; ++i2) {
+			spill_t *sp2 = spills[i2];
+
+			if (sp1->ent != sp2->ent)
+				continue;
+
+			if (my_values_interfere(sp1->spill, sp2->spill)) {
+				ir_fprintf(stderr, "Verify warning: Spillslots for %+F in block %+F(%s) and %+F in block %+F(%s) interfere\n",
+					sp1->spill, get_nodes_block(sp1->spill), get_irg_name(env->irg),
+					sp2->spill, get_nodes_block(sp2->spill), get_irg_name(env->irg));
+				env->problem_found = true;
+				my_values_interfere(sp1->spill, sp2->spill);
+			}
+		}
+	}
+}
+
+static void check_lonely_spills(ir_node *node, void *data)
+{
+	be_verify_spillslots_env_t *env = (be_verify_spillslots_env_t*)data;
+
+	if (be_is_Spill(node) || (is_Proj(node) && be_is_MemPerm(get_Proj_pred(node)))) {
+		spill_t *spill = find_spill(env, node);
+		if (be_is_Spill(node)) {
+			ir_entity *ent = arch_get_frame_entity(node);
+			be_check_entity(env, node, ent);
+		}
+
+		if (spill == NULL) {
+			ir_fprintf(stderr, "Verify warning: Node %+F in block %+F(%s) not connected to a reload\n",
+			           node, get_nodes_block(node), get_irg_name(env->irg));
+		}
+	}
+}
+
+bool be_verify_spillslots(ir_graph *irg)
+{
+	be_verify_spillslots_env_t env;
+
+	env.irg           = irg;
+	env.spills        = new_set(cmp_spill, 10);
+	env.reloads       = NEW_ARR_F(ir_node*, 0);
+	env.problem_found = false;
+
+	irg_walk_graph(irg, collect_spills_walker, NULL, &env);
+	irg_walk_graph(irg, check_lonely_spills, NULL, &env);
+
+	check_spillslot_interference(&env);
+
+	DEL_ARR_F(env.reloads);
+	del_set(env.spills);
+
+	return ! env.problem_found;
+}
+
+/*--------------------------------------------------------------------------- */
+
+/**
+ * Check, if two values interfere.
+ * @param a The first value.
+ * @param b The second value.
+ * @return 1, if a and b interfere, 0 if not.
+ */
+static bool my_values_interfere(const ir_node *a, const ir_node *b)
+{
+	int a2b = value_dominates(a, b);
+	int b2a = value_dominates(b, a);
+
+	/* If there is no dominance relation, they do not interfere. */
+	if (!a2b && !b2a)
+		return false;
+
+	/*
+	 * Adjust a and b so, that a dominates b if
+	 * a dominates b or vice versa.
+	 */
+	if (b2a) {
+		const ir_node *t = a;
+		a = b;
+		b = t;
+	}
+
+	ir_node *bb = get_nodes_block(b);
+
+	/*
+	 * Look at all usages of a.
+	 * If there's one usage of a in the block of b, then
+	 * we check, if this use is dominated by b, if that's true
+	 * a and b interfere. Note that b must strictly dominate the user,
+	 * since if b is the last user of in the block, b and a do not
+	 * interfere.
+	 * Uses of a not in b's block can be disobeyed, because the
+	 * check for a being live at the end of b's block is already
+	 * performed.
+	 */
+	foreach_out_edge(a, edge) {
+		const ir_node *user = get_edge_src_irn(edge);
+		if (b == user)
+			continue;
+
+		if (get_irn_opcode(user) == iro_End)
+			continue;
+
+		/* in case of phi arguments we compare with the block the value comes from */
+		if (is_Phi(user)) {
+			ir_node *phiblock = get_nodes_block(user);
+			if (phiblock == bb)
+				continue;
+			user = get_irn_n(phiblock, get_edge_src_pos(edge));
+		}
+
+		if (value_dominates(b, user))
+			return true;
+	}
+
+	return false;
+}
+
+/*--------------------------------------------------------------------------- */
+
+static const arch_env_t  *arch_env;
+static ir_graph          *irg;
+static be_lv_t           *lv;
+static bool               problem_found;
+static const ir_node    **registers;
+
+static void check_output_constraints(const ir_node *node)
+{
+	if (arch_get_irn_reg_class(node) == NULL)
+		return;
+
+	/* verify output register */
+	const arch_register_req_t *req = arch_get_irn_register_req(node);
+	const arch_register_t     *reg = arch_get_irn_register(node);
+	if (reg == NULL) {
+		ir_fprintf(stderr, "Verify warning: Node %+F in block %+F(%s) should have a register assigned\n",
+				node, get_nodes_block(node), get_irg_name(irg));
+		problem_found = true;
+	} else if (!arch_reg_is_allocatable(req, reg)) {
+		ir_fprintf(stderr, "Verify warning: Register %s assigned as output of %+F not allowed (register constraint) in block %+F(%s)\n",
+				reg->name, node, get_nodes_block(node), get_irg_name(irg));
+		problem_found = true;
+	}
+}
+
+static void check_input_constraints(ir_node *node)
+{
+	/* verify input register */
+	int arity = get_irn_arity(node);
+	for (int i = 0; i < arity; ++i) {
+		ir_node *pred = get_irn_n(node, i);
+		if (is_Bad(pred)) {
+			ir_fprintf(stderr, "Verify warning: %+F in block %+F(%s) has Bad as input %d\n",
+				node, get_nodes_block(node), get_irg_name(irg), i);
+			problem_found = 1;
+			continue;
+		}
+
+		const arch_register_req_t *req = arch_get_irn_register_req_in(node, i);
+		if (req->cls == NULL)
+			continue;
+
+		const arch_register_req_t *pred_req = arch_get_irn_register_req(pred);
+		if (req->width > pred_req->width) {
+			ir_fprintf(stderr, "Verify warning: %+F in block %+F(%s) register width of value at input %d too small\n",
+			           node, get_nodes_block(node), get_irg_name(irg), i);
+			problem_found = 1;
+		}
+
+		const arch_register_t *reg = arch_get_irn_register(pred);
+		if (reg == NULL) {
+			ir_fprintf(stderr, "Verify warning: Node %+F in block %+F(%s) should have a register assigned (%+F input constraint)\n",
+			           pred, get_nodes_block(pred), get_irg_name(irg), node);
+			problem_found = 1;
+			continue;
+		} else if (!arch_reg_is_allocatable(req, reg)) {
+			ir_fprintf(stderr, "Verify warning: Register %s as input %d of %+F not allowed (register constraint) in block %+F(%s)\n",
+			           reg->name, i, node, get_nodes_block(node), get_irg_name(irg));
+			problem_found = 1;
+		}
+	}
+
+	/* phis should be NOPs at this point, which means all input regs
+	 * must be the same as the output reg */
+	if (is_Phi(node)) {
+		const arch_register_t *reg = arch_get_irn_register(node);
+
+		int arity = get_irn_arity(node);
+		for (int i = 0; i < arity; ++i) {
+			ir_node               *pred     = get_Phi_pred(node, i);
+			const arch_register_t *pred_reg = arch_get_irn_register(pred);
+
+			if (reg != pred_reg && !(pred_reg->type & arch_register_type_virtual)) {
+				const char *pred_name = pred_reg != NULL ? pred_reg->name : "(null)";
+				const char *reg_name  = reg != NULL ? reg->name : "(null)";
+				ir_fprintf(stderr, "Verify warning: Input %d of %+F in block %+F(%s) uses register %s instead of %s\n",
+				           i, node, get_nodes_block(node),
+				           get_irg_name(irg), pred_name, reg_name);
+				problem_found = true;
+			}
+		}
+	}
+}
+
+static void value_used(const ir_node *block, const ir_node *node)
+{
+	const arch_register_t *reg = arch_get_irn_register(node);
+	if (reg == NULL || reg->type & arch_register_type_virtual)
+		return;
+
+	const arch_register_req_t *req = arch_get_irn_register_req(node);
+	assert(req->width > 0);
+	unsigned idx = reg->global_index;
+	for (unsigned i = 0; i < req->width; ++i) {
+		const ir_node *reg_node = registers[idx+i];
+		if (reg_node != NULL && reg_node != node) {
+			ir_fprintf(stderr, "Verify warning: Register %s assigned more than once in block %+F(%s) (nodes %+F %+F)\n",
+					   reg->name, block, get_irg_name(irg),
+					   node, reg_node);
+			problem_found = true;
+		}
+		registers[idx+i] = node;
+	}
+}
+
+static void value_def(const ir_node *node)
+{
+	const arch_register_t *reg = arch_get_irn_register(node);
+
+	if (reg == NULL || reg->type & arch_register_type_virtual)
+		return;
+
+	const arch_register_req_t *req = arch_get_irn_register_req(node);
+	assert(req->width > 0);
+	unsigned idx = reg->global_index;
+	for (unsigned i = 0; i < req->width; ++i) {
+		const ir_node *reg_node = registers[idx+i];
+
+		/* a little cheat, since its so hard to remove all outedges to dead code
+		 * in the backend. This particular case should never be a problem. */
+		if (reg_node == NULL && get_irn_n_edges(node) == 0)
+			return;
+
+		if (reg_node != node) {
+			ir_fprintf(stderr, "Verify warning: Node %+F not registered as value for Register %s (but %+F) in block %+F(%s)\n",
+			           node, reg->name, reg_node, get_nodes_block(node),
+			           get_irg_name(irg));
+			problem_found = true;
+		}
+		registers[idx+i] = NULL;
+	}
+}
+
+static void verify_block_register_allocation(ir_node *block, void *data)
+{
+	(void) data;
+
+	assert(lv->sets_valid && "live sets must be computed");
+
+	unsigned n_regs = arch_env->n_registers;
+	registers = ALLOCANZ(const ir_node*, n_regs);
+
+	be_lv_foreach(lv, block, be_lv_state_end, lv_node) {
+		value_used(block, lv_node);
+	}
+
+	sched_foreach_reverse(block, node) {
+		be_foreach_value(node, value,
+			value_def(value);
+			check_output_constraints(value);
+		);
+
+		check_input_constraints(node);
+
+		/* process uses. (Phi inputs are no real uses) */
+		if (!is_Phi(node)) {
+			int arity = get_irn_arity(node);
+			for (int in = 0; in < arity; ++in) {
+				ir_node *use = get_irn_n(node, in);
+				value_used(block, use);
+			}
+		}
+	}
+
+	be_lv_foreach(lv, block, be_lv_state_in, lv_node) {
+		value_def(lv_node);
+	}
+
+	/* set must be empty now */
+	for (unsigned i = 0; i < n_regs; ++i) {
+		if (registers[i] == NULL)
+			continue;
+
+		ir_fprintf(stderr, "Verify warning: Node %+F not live-in and no def found in block %+F(%s)\n",
+				registers[i], block, get_irg_name(irg));
+		problem_found = true;
+	}
+}
+
+bool be_verify_register_allocation(ir_graph *new_irg)
+{
+	irg           = new_irg;
+	arch_env      = be_get_irg_arch_env(irg);
+	lv            = be_liveness_new(irg);
+	problem_found = false;
+
+	be_liveness_compute_sets(lv);
+	irg_block_walk_graph(irg, verify_block_register_allocation, NULL, NULL);
+	be_liveness_free(lv);
+
+	return !problem_found;
+}
+
+/*--------------------------------------------------------------------------- */
+
+typedef struct lv_walker_t {
+	be_lv_t *lv;
+	void *data;
+} lv_walker_t;
+
+static const char *lv_flags_to_str(unsigned flags)
+{
+	static const char *states[] = {
+		"---",
+		"i--",
+		"-e-",
+		"ie-",
+		"--o",
+		"i-o",
+		"-eo",
+		"ieo"
+	};
+
+	return states[flags & 7];
+}
+
+static void lv_check_walker(ir_node *bl, void *data)
+{
+	lv_walker_t *w     = (lv_walker_t*)data;
+	be_lv_t     *fresh = (be_lv_t*)w->data;
+
+	be_lv_info_t *curr = ir_nodehashmap_get(be_lv_info_t, &fresh->map, bl);
+	be_lv_info_t *fr   = ir_nodehashmap_get(be_lv_info_t, &fresh->map, bl);
+
+	if (!fr && curr && curr[0].head.n_members > 0) {
+		ir_fprintf(stderr, "%+F liveness should be empty but current liveness contains:\n", bl);
+		for (unsigned i = 0; i < curr[0].head.n_members; ++i) {
+			ir_fprintf(stderr, "\t%+F\n", curr[1 + i].node.node);
+		}
+	} else if (curr) {
+		unsigned n_curr  = curr[0].head.n_members;
+		unsigned n_fresh = fr[0].head.n_members;
+
+		if (n_curr != n_fresh) {
+			ir_fprintf(stderr, "%+F: liveness set sizes differ. curr %d, correct %d\n", bl, n_curr, n_fresh);
+
+			ir_fprintf(stderr, "current:\n");
+			for (unsigned i = 0; i < n_curr; ++i) {
+				be_lv_info_node_t *n = &curr[1 + i].node;
+				ir_fprintf(stderr, "%+F %u %+F %s\n", bl, i, n->node, lv_flags_to_str(n->flags));
+			}
+
+			ir_fprintf(stderr, "correct:\n");
+			for (unsigned i = 0; i < n_fresh; ++i) {
+				be_lv_info_node_t *n = &fr[1 + i].node;
+				ir_fprintf(stderr, "%+F %u %+F %s\n", bl, i, n->node, lv_flags_to_str(n->flags));
+			}
+		}
+	}
+}
+
+void be_liveness_check(be_lv_t *lv)
+{
+	lv_walker_t w;
+	be_lv_t *fresh = be_liveness_new(lv->irg);
+
+	w.lv   = lv;
+	w.data = fresh;
+	irg_block_walk_graph(lv->irg, lv_check_walker, NULL, &w);
+	be_liveness_free(fresh);
+}