regrename.c (find_oldest_value_reg): Ignore the value chain if the original…

regrename.c (find_oldest_value_reg): Ignore the value chain if the original register was copied in a mode with a...

        * regrename.c (find_oldest_value_reg): Ignore the value chain if
        the original register was copied in a mode with a fewer number of
        hard registers than the desired mode.
        (copyprop_hardreg_forward_1): Likewise.
        (debug_value_data): Fix loop test.
        * toplev.c (parse_options_and_default_flags): Reenable
        -fcprop-registers at -O1.

From-SVN: r48624

gcc/ChangeLog

-002-01-07  Aldy Hernandez  <aldyh@redhat.com>
+2002-01-07  Richard Henderson  <rth@redhat.com>
+
+	* regrename.c (find_oldest_value_reg): Ignore the value chain if
+	the original register was copied in a mode with a fewer number of
+	hard registers than the desired mode.
+	(copyprop_hardreg_forward_1): Likewise.
+	(debug_value_data): Fix loop test.
+	* toplev.c (parse_options_and_default_flags): Reenable
+	-fcprop-registers at -O1.
+
+2002-01-07  Aldy Hernandez  <aldyh@redhat.com>
 
         * config/rs6000/rs6000.c (bdesc_2arg): Add altivec predicates.
         (altivec_init_builtins): New node v4si_ftype_v16qi_v16qi.

gcc/regrename.c

@@ -1282,6 +1282,20 @@ find_oldest_value_reg (class, reg, vd)
   enum machine_mode mode = GET_MODE (reg);
   unsigned int i;
 
+  /* If we are accessing REG in some mode other that what we set it in,
+     make sure that the replacement is valid.  In particular, consider
+	(set (reg:DI r11) (...))
+	(set (reg:SI r9) (reg:SI r11))
+	(set (reg:SI r10) (...))
+	(set (...) (reg:DI r9))
+     Replacing r9 with r11 is invalid.  */
+  if (mode != vd->e[regno].mode)
+    {
+      if (HARD_REGNO_NREGS (regno, mode)
+	  > HARD_REGNO_NREGS (regno, vd->e[regno].mode))
+	return NULL_RTX;
+    }
+
   for (i = vd->e[regno].oldest_regno; i != regno; i = vd->e[i].next_regno)
     if (TEST_HARD_REG_BIT (reg_class_contents[class], i)
 	&& (vd->e[i].mode == mode
@@ -1544,6 +1558,15 @@ copyprop_hardreg_forward_1 (bb, vd)
 	  unsigned int i;
 	  rtx new;
 
+	  /* If we are accessing SRC in some mode other that what we
+	     set it in, make sure that the replacement is valid.  */
+	  if (mode != vd->e[regno].mode)
+	    {
+	      if (HARD_REGNO_NREGS (regno, mode)
+		  > HARD_REGNO_NREGS (regno, vd->e[regno].mode))
+		goto no_move_special_case;
+	    }
+
 	  /* If the destination is also a register, try to find a source
 	     register in the same class.  */
 	  if (REG_P (SET_DEST (set)))
@@ -1578,6 +1601,7 @@ copyprop_hardreg_forward_1 (bb, vd)
 		  }
 	      }
 	}
+      no_move_special_case:
 
       /* For each input operand, replace a hard register with the
 	 eldest live copy that's in an appropriate register class.  */
@@ -1735,7 +1759,7 @@ debug_value_data (vd)
 	     j != INVALID_REGNUM;
 	     j = vd->e[j].next_regno)
 	  {
-	    if (TEST_HARD_REG_BIT (set, vd->e[j].next_regno))
+	    if (TEST_HARD_REG_BIT (set, j))
 	      {
 		fprintf (stderr, "[%u] Loop in regno chain\n", j);
 		return;

gcc/toplev.c

@@ -4663,7 +4663,7 @@ parse_options_and_default_flags (argc, argv)
       flag_omit_frame_pointer = 1;
 #endif
       flag_guess_branch_prob = 1;
-      /* flag_cprop_registers = 1; */
+      flag_cprop_registers = 1;
     }
 
   if (optimize >= 2)