re PR tree-optimization/45950 (ICE segmentation fault compiling __udivdi3)

	PR tree-optimization/45950
	* tree-ssa-sccvn.c (init_vn_nary_op_from_pieces): Consult length
	before initializing vno->op.

From-SVN: r165220

gcc/ChangeLog

+2010-10-09  Nathan Froyd  <froydnj@codesourcery.com>
+
+	PR tree-optimization/45950
+	* tree-ssa-sccvn.c (init_vn_nary_op_from_pieces): Consult length
+	before initializing vno->op.
+
 2010-10-09  Ralf Corsépius <ralf.corsepius@rtems.org>
 
 	* config.gcc (bfin*-rtems*): Add newlib-stdint.h.

gcc/tree-ssa-sccvn.c

@@ -1708,10 +1708,16 @@ init_vn_nary_op_from_pieces (vn_nary_op_t vno, unsigned int length,
   vno->opcode = code;
   vno->length = length;
   vno->type = type;
-  vno->op[0] = op0;
-  vno->op[1] = op1;
-  vno->op[2] = op2;
-  vno->op[3] = op3;
+  switch (length)
+    {
+      /* The fallthrus here are deliberate.  */
+    case 4: vno->op[3] = op3;
+    case 3: vno->op[2] = op2;
+    case 2: vno->op[1] = op1;
+    case 1: vno->op[0] = op0;
+    default:
+      break;
+    }
 }
 
 /* Initialize VNO from OP.  */