rtlanal.c (find_first_parameter_load): Rewrite to return actual first param load…

rtlanal.c (find_first_parameter_load): Rewrite to return actual first param load or the call if none...

2005-03-16 Dale Johannesen  <dalej@apple.com>

        * rtlanal.c (find_first_parameter_load):  Rewrite to
        return actual first param load or the call if none,
        instead of first in block, when not all loads exist.

From-SVN: r96578

gcc/ChangeLog

+2005-03-16 Dale Johannesen  <dalej@apple.com>
+
+	* rtlanal.c (find_first_parameter_load):  Rewrite to
+	return actual first param load or the call if none,
+	instead of first in block, when not all loads exist.
+
 2005-03-16  Roger Sayle  <roger@eyesopen.com>
 
 	* optabs.c (expand_copysign_absneg): Make static.

gcc/rtlanal.c

@@ -3159,12 +3159,15 @@ parms_set (rtx x, rtx pat ATTRIBUTE_UNUSED, void *data)
 }
 
 /* Look backward for first parameter to be loaded.
+   Note that loads of all parameters will not necessarily be
+   found if CSE has eliminated some of them (e.g., an argument
+   to the outer function is passed down as a parameter).
    Do not skip BOUNDARY.  */
 rtx
 find_first_parameter_load (rtx call_insn, rtx boundary)
 {
   struct parms_set_data parm;
-  rtx p, before;
+  rtx p, before, first_set;
 
   /* Since different machines initialize their parameter registers
      in different orders, assume nothing.  Collect the set of all
@@ -3186,6 +3189,7 @@ find_first_parameter_load (rtx call_insn, rtx boundary)
 	parm.nregs++;
       }
   before = call_insn;
+  first_set = call_insn;
 
   /* Search backward for the first set of a register in this set.  */
   while (parm.nregs && before != boundary)
@@ -3208,9 +3212,20 @@ find_first_parameter_load (rtx call_insn, rtx boundary)
 	}
 
       if (INSN_P (before))
-	note_stores (PATTERN (before), parms_set, &parm);
+	{
+	  int nregs_old = parm.nregs;
+	  note_stores (PATTERN (before), parms_set, &parm);
+	  /* If we found something that did not set a parameter reg,
+	     we're done.  Do not keep going, as that might result
+	     in hoisting an insn before the setting of a pseudo
+	     that is used by the hoisted insn. */
+	  if (nregs_old != parm.nregs)
+	    first_set = before;
+	  else
+	    break;
+	}
     }
-  return before;
+  return first_set;
 }
 
 /* Return true if we should avoid inserting code between INSN and preceding