[Qemu-devel] [4512] fixed dead global variable update

[Fabrice Bellard <fabrice@bellard.org>]

Revision: 4512
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=4512
Author:   bellard
Date:     2008-05-21 16:24:20 +0000 (Wed, 21 May 2008)

Log Message:
-----------
fixed dead global variable update

Modified Paths:
--------------
    trunk/tcg/tcg.c

Modified: trunk/tcg/tcg.c
===================================================================
--- trunk/tcg/tcg.c	2008-05-21 13:34:27 UTC (rev 4511)
+++ trunk/tcg/tcg.c	2008-05-21 16:24:20 UTC (rev 4512)
@@ -1293,10 +1293,9 @@
     tcg_abort();
 }
 
-/* at the end of a basic block, we assume all temporaries are dead and
-   all globals are stored at their canonical location */
-/* XXX: optimize by handling constants in another array ? */
-void tcg_reg_alloc_bb_end(TCGContext *s)
+/* save globals to their cannonical location and assume they can be
+   modified be the following code. */
+static void save_globals(TCGContext *s)
 {
     TCGTemp *ts;
     int i;
@@ -1306,10 +1305,23 @@
         if (!ts->fixed_reg) {
             if (ts->val_type == TEMP_VAL_REG) {
                 tcg_reg_free(s, ts->reg);
+            } else if (ts->val_type == TEMP_VAL_DEAD) {
+                ts->val_type = TEMP_VAL_MEM;
             }
         }
     }
+}
 
+/* at the end of a basic block, we assume all temporaries are dead and
+   all globals are stored at their canonical location */
+/* XXX: optimize by handling constants in another array ? */
+void tcg_reg_alloc_bb_end(TCGContext *s)
+{
+    TCGTemp *ts;
+    int i;
+
+    save_globals(s);
+
     for(i = s->nb_globals; i < s->nb_temps; i++) {
         ts = &s->temps[i];
         if (ts->val_type != TEMP_VAL_CONST) {
@@ -1481,14 +1493,7 @@
 
         /* store globals and free associated registers (we assume the insn
            can modify any global. */
-        for(i = 0; i < s->nb_globals; i++) {
-            ts = &s->temps[i];
-            if (!ts->fixed_reg) {
-                if (ts->val_type == TEMP_VAL_REG) {
-                    tcg_reg_free(s, ts->reg);
-                }
-            }
-        }
+        save_globals(s);
     }
 
     /* satisfy the output constraints */
@@ -1680,14 +1685,7 @@
     
     /* store globals and free associated registers (we assume the call
        can modify any global. */
-    for(i = 0; i < s->nb_globals; i++) {
-        ts = &s->temps[i];
-        if (!ts->fixed_reg) {
-            if (ts->val_type == TEMP_VAL_REG) {
-                tcg_reg_free(s, ts->reg);
-            }
-        }
-    }
+    save_globals(s);
 
     tcg_out_op(s, opc, &func_arg, &const_func_arg);