(tablejump): Add SIGN_EXTEND to HImode offset so can add to SImode PC.

Likewise for matching pattern.

From-SVN: r7938

gcc/config/m68k/m68k.md

@@ -4492,7 +4492,8 @@
   "
 {
 #ifdef CASE_VECTOR_PC_RELATIVE
-    operands[0] = gen_rtx (PLUS, SImode, pc_rtx, operands[0]);
+    operands[0] = gen_rtx (PLUS, SImode, pc_rtx,
+			   gen_rtx (SIGN_EXTEND, SImode, operands[0]));
 #endif
 }")
 
@@ -4512,7 +4513,8 @@
 ;; Jump to variable address from dispatch table of relative addresses.
 (define_insn ""
   [(set (pc)
-	(plus:SI (pc) (match_operand:HI 0 "register_operand" "r")))
+	(plus:SI (pc)
+		 (sign_extend:SI (match_operand:HI 0 "register_operand" "r"))))
    (use (label_ref (match_operand 1 "" "")))]
   ""
   "*