non-LVU: error if .[su]leb128's operand is undefined

gas/testsuite/gas/all/gas.exp

@@ -394,6 +394,7 @@ if { ![istarget "tic4x*-*-*"] && ![istarget "tic54x*-*-*"] } {
     run_dump_test sleb128-7
     run_dump_test sleb128-8
 }
+run_dump_test sleb128-9
 
 # .byte is 32 bits on tic4x, and .p2align isn't supported on tic54x
 # .space is different on hppa*-hpux.

gas/testsuite/gas/all/sleb128-9.d

@@ -0,0 +1,4 @@
+#name: undefined symbols un sleb128 directive
+#source: sleb128-9.s
+#error-output: sleb128-9.l
+#target: *-*-*

gas/testsuite/gas/all/sleb128-9.l

@@ -0,0 +1,3 @@
+[^:]*: Assembler messages:
+[^:]*:2: Error: leb128 operand is an undefined symbol: \.Lundef
+[^:]*:3: Error: leb128 operand is an undefined symbol: undef

gas/testsuite/gas/all/sleb128-9.s

@@ -0,0 +1,3 @@
+	.data
+	.sleb128 .Lundef
+	.sleb128 undef

gas/write.c

@@ -2447,6 +2447,13 @@ relax_segment (struct frag *segment_frag_root, segT segment, int pass)
 #endif
 
 	case rs_leb128:
+	  if (pass == 0 && !S_IS_DEFINED (fragP->fr_symbol))
+	      {
+		as_bad_where (fragP->fr_file, fragP->fr_line,
+			      _("leb128 operand is an undefined symbol: %s"),
+			      S_GET_NAME (fragP->fr_symbol));
+	      }
+	    
 	  /* Initial guess is always 1; doing otherwise can result in
 	     stable solutions that are larger than the minimum.  */
 	  address += fragP->fr_offset = 1;