X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Fbe%2Fbeflags.c;h=97905da5d10c3e1bc3c8af3888dd173b5013d825;hb=2669742071b00949c6a5102f39b7df7fd7d3e3fb;hp=090a1b7cf61724cc28108507169b9febb4ff6e97;hpb=897c780100ab59a7968eef621f2fa47bd711b089;p=libfirm

diff --git a/ir/be/beflags.c b/ir/be/beflags.c
index 090a1b7cf..97905da5d 100644
--- a/ir/be/beflags.c
+++ b/ir/be/beflags.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1995-2007 University of Karlsruhe.  All right reserved.
+ * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
  *
  * This file is part of libFirm.
  *
@@ -22,6 +22,18 @@
  * @brief       modifies schedule so flags dependencies are respected.
  * @author      Matthias Braun, Christoph Mallon
  * @version     $Id: besched.h 14693 2007-06-21 15:35:49Z beck $
+ *
+ * Fixup schedule to respect flag constraints by moving and rematerialisation of
+ * nodes.
+ *
+ * Flags are modeled as register classes with ignore registers. However to avoid
+ * bloating the graph, only flag-consumer -> producer dependencies are
+ * explicitely modeled in the graph. Nodes that just change the flags are only
+ * marked with the arch_irn_flags_modify_flags flag.
+ *
+ * Flags are usually a limited resource that can't (or at least shouldn't) be
+ * spilled. So in some situations (for example 2 adc-nodes that use the flags of
+ * a single add node on x86) operations have to be repeated to work correctly.
  */
 #ifdef HAVE_CONFIG_H
 #include "config.h"
@@ -39,15 +51,24 @@
 #include "bearch_t.h"
 #include "beirg_t.h"
 #include "besched_t.h"
+#include "benode_t.h"
 
 static const arch_env_t            *arch_env   = NULL;
 static const arch_register_class_t *flag_class = NULL;
 static const arch_register_t       *flags_reg  = NULL;
 static func_rematerialize           remat      = NULL;
+static int                          changed;
 
 static ir_node *default_remat(ir_node *node, ir_node *after)
 {
-	ir_node *copy  = exact_copy(node);
+	ir_node *block, *copy;
+	if(is_Block(after))
+		block = after;
+	else
+		block = get_nodes_block(after);
+
+	copy = exact_copy(node);
+	set_nodes_block(copy, block);
 	sched_add_after(after, copy);
 
 	return copy;
@@ -76,7 +97,19 @@ static int can_move(ir_node *node, ir_node *after)
 				/* phi represents a usage at block end */
 				if(is_Phi(out2))
 					continue;
-				if(sched_get_time_step(out2) <= sched_get_time_step(after)) {
+				if(is_Sync(out2)) {
+					const ir_edge_t *edge3;
+					foreach_out_edge(out2, edge3) {
+						ir_node *out3 = get_edge_src_irn(edge3);
+						/* phi represents a usage at block end */
+						if(is_Phi(out3))
+							continue;
+						assert(!is_Sync(out3));
+						if(sched_get_time_step(out3) <= sched_get_time_step(after)) {
+							return 0;
+						}
+					}
+				} else if(sched_get_time_step(out2) <= sched_get_time_step(after)) {
 					return 0;
 				}
 			}
@@ -90,25 +123,28 @@ static int can_move(ir_node *node, ir_node *after)
 		}
 	}
 
-	ir_fprintf(stderr, "Can move node %+F after node %+F\n", node, after);
 	return 1;
 }
 
 static void rematerialize_or_move(ir_node *flags_needed, ir_node *node,
-                                  ir_node *flag_consumers, int pn)
+                                  ir_node *flag_consumers, int pn, be_lv_t *lv)
 {
 	ir_node *n;
 	ir_node *copy;
 	ir_node *value;
 
-	if(can_move(flags_needed, node)) {
+	if(!is_Block(node) &&
+			get_nodes_block(flags_needed) == get_nodes_block(node) &&
+			can_move(flags_needed, node)) {
 		/* move it */
 		sched_remove(flags_needed);
 		sched_add_after(node, flags_needed);
+		/* No need to update liveness, because the node stays in the same block */
 		return;
 	}
 
-	copy = remat(flags_needed, node);
+	changed = 1;
+	copy    = remat(flags_needed, node);
 
 	if(get_irn_mode(copy) == mode_T) {
 		ir_node *block = get_nodes_block(copy);
@@ -133,38 +169,76 @@ static void rematerialize_or_move(ir_node *flags_needed, ir_node *node,
 		}
 		n = get_irn_link(n);
 	} while(n != NULL);
+
+	/* No need to introduce the copy, because it only lives in this block, but
+	 * we have to update the liveness of all operands */
+	if (is_Block(node) ||
+			get_nodes_block(node) != get_nodes_block(flags_needed)) {
+		int i;
+
+		for (i = get_irn_arity(copy) - 1; i >= 0; --i) {
+			be_liveness_update(lv, get_irn_n(copy, i));
+		}
+	}
+}
+
+static int is_modify_flags(ir_node *node) {
+	int i, arity;
+
+	if(arch_irn_is(arch_env, node, modify_flags))
+		return 1;
+	if(!be_is_Keep(node))
+		return 0;
+
+	arity = get_irn_arity(node);
+	for(i = 0; i < arity; ++i) {
+		ir_node *in = get_irn_n(node, i);
+		in = skip_Proj(in);
+		if(arch_irn_is(arch_env, in, modify_flags))
+			return 1;
+	}
+
+	return 0;
 }
 
+/**
+ * walks up the schedule and makes sure there are no flag-destroying nodes
+ * between a flag-consumer -> flag-producer chain. Fixes problematic situations
+ * by moving and/or rematerialisation of the flag-producers.
+ * (This can be extended in the future to do some register allocation on targets
+ *  like ppc32 where we conceptually have 8 flag registers)
+ */
 static void fix_flags_walker(ir_node *block, void *env)
 {
 	ir_node *node;
 	ir_node *flags_needed   = NULL;
 	ir_node *flag_consumers = NULL;
-	int      pn;
-	(void) env;
+	int      pn = -1;
 
 	sched_foreach_reverse(block, node) {
 		int i, arity;
 		ir_node *new_flags_needed = NULL;
 
+		if(is_Phi(node))
+			break;
+
 		if(node == flags_needed) {
 			/* all ok */
 			flags_needed   = NULL;
 			flag_consumers = NULL;
 		}
 
-		/* test wether node destroys the flags */
-		if(flags_needed != NULL && arch_irn_is(arch_env, node, modify_flags)) {
+		/* test whether node destroys the flags */
+		if(flags_needed != NULL && is_modify_flags(node)) {
 			/* rematerialize */
-			rematerialize_or_move(flags_needed, node, flag_consumers, pn);
+			rematerialize_or_move(flags_needed, node, flag_consumers, pn, env);
 			flags_needed   = NULL;
 			flag_consumers = NULL;
 		}
 
-		/* test wether the current node needs flags */
+		/* test whether the current node needs flags */
 		arity = get_irn_arity(node);
 		for(i = 0; i < arity; ++i) {
-			//ir_node *in = get_irn_n(node, i);
 			const arch_register_class_t *cls
 				= arch_get_irn_reg_class(arch_env, node, i);
 			if(cls == flag_class) {
@@ -176,36 +250,40 @@ static void fix_flags_walker(ir_node *block, void *env)
 		if(new_flags_needed == NULL)
 			continue;
 
-		if(new_flags_needed != flags_needed) {
+		/* spiller can't (correctly) remat flag consumers at the moment */
+		assert(!arch_irn_is(arch_env, node, rematerializable));
+
+		if(skip_Proj(new_flags_needed) != flags_needed) {
 			if(flags_needed != NULL) {
 				/* rematerialize node */
-				rematerialize_or_move(flags_needed, node, flag_consumers, pn);
-				flags_needed    = NULL;
+				rematerialize_or_move(flags_needed, node, flag_consumers, pn, env);
+				flags_needed   = NULL;
 				flag_consumers = NULL;
 			}
 
-			if(get_nodes_block(new_flags_needed) != block) {
-				panic("remat across blocks not implemented yet");
-				flags_needed   = NULL;
-				flag_consumers = NULL;
-			} else {
-				flags_needed = new_flags_needed;
-				arch_set_irn_register(arch_env, flags_needed, flags_reg);
-				if(is_Proj(flags_needed)) {
-					pn           = get_Proj_proj(flags_needed);
-					flags_needed = get_Proj_pred(flags_needed);
-				}
-				flag_consumers = node;
-				set_irn_link(flag_consumers, NULL);
-				assert(arch_irn_is(arch_env, flags_needed, rematerializable));
+			flags_needed = new_flags_needed;
+			arch_set_irn_register(arch_env, flags_needed, flags_reg);
+			if(is_Proj(flags_needed)) {
+				pn           = get_Proj_proj(flags_needed);
+				flags_needed = get_Proj_pred(flags_needed);
 			}
+			flag_consumers = node;
+			set_irn_link(flag_consumers, NULL);
+			assert(arch_irn_is(arch_env, flags_needed, rematerializable));
 		} else {
 			/* link all consumers in a list */
-			set_irn_link(flag_consumers, node);
+			set_irn_link(node, flag_consumers);
 			flag_consumers = node;
 		}
 	}
 
+	if(flags_needed != NULL) {
+		assert(get_nodes_block(flags_needed) != block);
+		rematerialize_or_move(flags_needed, node, flag_consumers, pn, env);
+		flags_needed   = NULL;
+		flag_consumers = NULL;
+	}
+
 	assert(flags_needed   == NULL);
 	assert(flag_consumers == NULL);
 }
@@ -219,10 +297,15 @@ void be_sched_fix_flags(be_irg_t *birg, const arch_register_class_t *flag_cls,
 	flag_class = flag_cls;
 	flags_reg  = & flag_class->regs[0];
 	remat      = remat_func;
+	changed    = 0;
 	if(remat == NULL)
 		remat = &default_remat;
 
-	set_using_irn_link(irg);
-	irg_block_walk_graph(irg, fix_flags_walker, NULL, NULL);
-	clear_using_irn_link(irg);
+	ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
+	irg_block_walk_graph(irg, fix_flags_walker, NULL, birg->lv);
+	ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
+
+	if(changed) {
+		be_remove_dead_nodes_from_schedule(birg);
+	}
 }