regclass.c (reg_scan_mark_refs): Be more selective about when we mark a register…

regclass.c (reg_scan_mark_refs): Be more selective about when we mark a register with REGNO_POINTER_FLAG.

        * regclass.c (reg_scan_mark_refs): Be more selective about
        when we mark a register with REGNO_POINTER_FLAG.

From-SVN: r18849

gcc/ChangeLog

+Fri Mar 27 00:49:46 1998  Jeffrey A Law  (law@cygnus.com)
+
+	* regclass.c (reg_scan_mark_refs): Be more selective about
+	when we mark a register with REGNO_POINTER_FLAG.
+
 Thu Mar 26 23:00:11 1998  J"orn Rennecke <amylaar@cygnus.co.uk>
 
 	reload inheritance improvement:

gcc/regclass.c

@@ -1919,6 +1919,12 @@ reg_scan_mark_refs (x, insn, note_flag)
 
       if (GET_CODE (SET_DEST (x)) == REG
 	  && REGNO (SET_DEST (x)) >= FIRST_PSEUDO_REGISTER
+	  /* If the destination pseudo is set more than once, then other
+	     sets might not be to a pointer value (consider access to a
+	     union in two threads of control in the presense of global
+	     optimizations).  So only set REGNO_POINTER_FLAG on the destination
+	     pseudo if this is the only set of that pseudo.  */
+	  && REG_N_SETS (REGNO (SET_DEST (x))) == 1
 	  && ! REG_USERVAR_P (SET_DEST (x))
 	  && ! REGNO_POINTER_FLAG (REGNO (SET_DEST (x)))
 	  && ((GET_CODE (SET_SRC (x)) == REG