X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=ir%2Flower%2Flower_switch.c;h=d43f74d931e1db71f534f90e1f4560e44f73942f;hb=f864dbddcf026827e85d49544abbb002841a5405;hp=82c028326e92f46bf81ef996959671ada62bd77d;hpb=c8ebba14868a15755307bfdbe0f5327d1e792c3f;p=libfirm

diff --git a/ir/lower/lower_switch.c b/ir/lower/lower_switch.c
index 82c028326..d43f74d93 100644
--- a/ir/lower/lower_switch.c
+++ b/ir/lower/lower_switch.c
@@ -30,6 +30,7 @@
 
 #include <limits.h>
 
+#include "array_t.h"
 #include "ircons.h"
 #include "irgopt.h"
 #include "irgwalk.h"
@@ -41,7 +42,6 @@
 
 typedef struct walk_env {
 	unsigned         spare_size;        /**< the allowed spare size for table switches */
-	struct obstack   obst;              /**< the obstack where data is allocated on */
 	int              changed;           /**< indicates whether a change was performed */
 } walk_env_t;
 
@@ -72,21 +72,21 @@ static int should_do_table_switch(ir_node *cond, unsigned spare_size)
 	unsigned long spare, num_cases = 0;
 
 	/* TODO: Minimum size for jump table? */
-	if(get_irn_n_outs(cond) <= 4)
+	if (get_irn_n_outs(cond) <= 4)
 		return 0;
 
 	default_pn = get_Cond_defaultProj(cond);
 
 	foreach_out_irn(cond, i, proj) {
 		long pn = get_Proj_proj(proj);
-		if(pn == default_pn)
+		if (pn == default_pn)
 			continue;
 
-		if(pn < switch_min)
+		if (pn < switch_min)
 			switch_min = pn;
-		if(pn > switch_max)
+		if (pn > switch_max)
 			switch_max = pn;
-		num_cases++;
+		++num_cases;
 	}
 
 	/*
@@ -99,7 +99,9 @@ static int should_do_table_switch(ir_node *cond, unsigned spare_size)
 
 static int casecmp(const void *a, const void *b)
 {
-	return ((case_data_t *) a)->value - ((case_data_t *) b)->value;
+	const case_data_t *cda = a;
+	const case_data_t *cdb = b;
+	return cda->value - cdb->value;
 }
 
 /**
@@ -108,10 +110,14 @@ static int casecmp(const void *a, const void *b)
 static void create_if_cascade(ifcas_env_t *env, ir_node *curblock,
                               case_data_t *curcases, int numcases)
 {
+	assert(numcases >= 0);
+
 	set_cur_block(curblock);
 
-	if(numcases == 1)
-	{
+	if (numcases == 0) {
+		/* zero cases: "goto default;" */
+		env->defusers[env->defindex++] = new_Jmp();
+	} else if (numcases == 1) {
 		/* only one case: "if(sel == val) goto target else goto default;" */
 		ir_node *val  = new_Const_long(get_irn_mode(env->sel), curcases[0].value);
 		ir_node *cmp  = new_Cmp(env->sel, val);
@@ -119,7 +125,7 @@ static void create_if_cascade(ifcas_env_t *env, ir_node *curblock,
 		ir_node *cond = new_Cond(proj);
 		set_Block_cfgpred(curcases[0].target, 0, new_Proj(cond, mode_X, pn_Cond_true));
 		env->defusers[env->defindex++] = new_Proj(cond, mode_X, pn_Cond_false);
-	} else if(numcases == 2) {
+	} else if (numcases == 2) {
 		/* only two cases: "if(sel == val[0]) goto target[0];" */
 		ir_node *val  = new_Const_long(get_irn_mode(env->sel), curcases[0].value);
 		ir_node *cmp  = new_Cmp(env->sel, val);
@@ -180,34 +186,35 @@ static void find_cond_nodes(ir_node *block, void *ctx)
 	ir_node     *defblock = NULL;
 	ifcas_env_t  ifcas_env;
 
-	if(get_Block_n_cfgpreds(block) != 1)
+	if (get_Block_n_cfgpreds(block) != 1)
 		return;
 
 	projx = get_Block_cfgpred(block, 0);
-	if(!is_Proj(projx))
+	if (!is_Proj(projx))
 		return;
 	assert(get_irn_mode(projx) == mode_X);
 
 	cond = get_Proj_pred(projx);
-	if(!is_Cond(cond))
+	if (!is_Cond(cond))
 		return;
 
 	sel      = get_Cond_selector(cond);
 	sel_mode = get_irn_mode(sel);
 
-	if(sel_mode == mode_b)    /* not a switch? */
+	if (sel_mode == mode_b)    /* not a switch? */
 		return;
 
-	if(should_do_table_switch(cond, env->spare_size))
+	if (should_do_table_switch(cond, env->spare_size))
 		return;
 
 	/*
 	 * Switch should be transformed into an if cascade.
 	 * So first order the cases, so we can do a binary search on them.
 	 */
+	env->changed = 1;
 
 	numcases = get_irn_n_outs(cond) - 1;      // does not contain default case
-	cases    = obstack_alloc(&env->obst, numcases * sizeof(*cases));
+	NEW_ARR_A(case_data_t, cases, numcases);
 
 	default_pn = get_Cond_defaultProj(cond);
 	ifcas_env.sel = sel;
@@ -219,8 +226,7 @@ static void find_cond_nodes(ir_node *block, void *ctx)
 		ir_node *target = get_irn_out(proj, 0);
 		assert(get_Block_n_cfgpreds(target) == 1 && "Encountered critical edge in switch");
 
-		if(pn == default_pn)
-		{
+		if (pn == default_pn) {
 			defblock = target;
 			continue;
 		}
@@ -239,8 +245,6 @@ static void find_cond_nodes(ir_node *block, void *ctx)
 
 	/* Connect new default case users */
 	set_irn_in(defblock, ifcas_env.defindex, ifcas_env.defusers);
-
-	obstack_free(&env->obst, cases);
 }
 
 /**
@@ -251,14 +255,14 @@ static void find_cond_nodes(ir_node *block, void *ctx)
  * @param spare_size Allowed spare size for table switches in machine words.
  *                   (Default in edgfe: 128)
  */
-void lower_Switch(ir_graph *irg, unsigned spare_size)
+void lower_switch(ir_graph *irg, unsigned spare_size)
 {
 	walk_env_t env;
 	ir_graph *rem = current_ir_graph;
 
 	current_ir_graph = irg;
 
-	obstack_init(&env.obst);
+	env.changed    = 0;
 	env.spare_size = spare_size;
 
 	remove_critical_cf_edges(irg);
@@ -266,14 +270,12 @@ void lower_Switch(ir_graph *irg, unsigned spare_size)
 
 	irg_block_walk_graph(irg, find_cond_nodes, NULL, &env);
 
-	if(env.changed) {
+	if (env.changed) {
 		/* control flow changed */
 		set_irg_outs_inconsistent(irg);
 		set_irg_doms_inconsistent(irg);
 		set_irg_extblk_inconsistent(irg);
 		set_irg_loopinfo_inconsistent(irg);
 	}
-
-	obstack_free(&env.obst, NULL);
 	current_ir_graph = rem;
 }