--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/xlat/livevar.c	Tue Apr 07 10:55:03 2009 +0000
@@ -0,0 +1,96 @@
+/**
+ * $Id: livevar.h 931 2008-10-31 02:57:59Z nkeynes $
+ * 
+ * Live variable analysis
+ *
+ * Copyright (c) 2009 Nathan Keynes.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include "xlat/xir.h"
+#include "xlat/xiropt.h"
+
+
+gboolean live_range_calculate( xir_op_t start, xir_op_t end, 
+                               struct live_range *live_ranges, unsigned int live_ranges_size )
+{
+    struct live_range *current[MAX_REGISTERS];
+    struct live_range *range_next = live_ranges;
+    struct live_range *range_end = live_ranges + live_ranges_size;
+    xir_offset_t position = 0;
+    xir_offset_t last_exc = 0;
+    xir_op_t it;
+    
+    memset( current, 0, sizeof(current) );
+    
+    while( it != end ) {
+        int reg0 = -1;
+        int reg1 = -1;
+        
+        if( it->exc != NULL ) {
+            // Track when the last possible exception was
+            last_exc = position;
+        }
+        
+        if( XOP_READS_REG1(it) ) { // Update live-range for op0
+            reg0 = XOP_REG1(it);
+            if( current[reg0] == NULL ) {
+                current[reg0] = range_next++;
+                if( current[reg0] == range_end )
+                    return FALSE;
+                current[reg0]->start = it;
+                current[reg0]->offset = position;
+                current[reg0]->writeback = FALSE; // register is already coherent
+            }
+            current[reg0]->end = it;
+            current[reg0]->length = position - current[reg0]->offset;            
+        } 
+
+        if( XOP_READS_REG2(it) ) {
+            reg1 = XOP_REG2(it);
+            if( current[reg1] == NULL ) {
+                current[reg1] = range_next++;
+                if( current[reg1] == range_end )
+                    return FALSE;
+                current[reg1]->start = it;
+                current[reg1]->offset = position;
+            }
+            current[reg1]->end = it;
+            current[reg1]->length = position - current[reg1]->offset;
+        } // op1 is Use-only
+        
+        if( XOP_WRITES_REG1(it) ) {
+        }
+        
+        if( XOP_WRITES_REG2(it)  ) {
+            int reg = XOP_REG2(it);
+            if( last_exc < current[reg].end ) {
+                // Value is dead and doesn't need to be spilled.
+                current[reg].writeback = FALSE;
+            }
+            // Kill last range for op1 if we're not using it. Otherwise
+            // this is just a continuation.
+            current[reg] = range_next++;
+            if( current[reg] == range_end )
+                return FALSE;
+            current[reg]->start = it;
+            current[reg]->offset = position;
+            current[reg]->end = it;
+            current[reg]->length = 0;
+            current[reg]->writeback = TRUE;
+        }
+
+        it = it->next;
+        position++;
+    }
+    return TRUE;
+}
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