When reading string arguments for the assembler's string directives treat space separated strings as a single entity.

* read.c (stringer): Treat space separated, quote enclosed strings
	as a single string.
	* doc/as.texi (asciz): Mention this behaviour in the description
	of the asciz directive.
	* testsuite/gas/all/asciz.s: New test.
	* testsuite/gas/all/asciz.d: New test driver.
	* testsuite/gas/all/gas.exp: Run the new test.

gas/doc/as.texi

@@ -4662,7 +4662,9 @@ trailing zero byte) into consecutive addresses.
 @cindex zero-terminated strings
 @cindex null-terminated strings
 @code{.asciz} is just like @code{.ascii}, but each string is followed by
-a zero byte.  The ``z'' in @samp{.asciz} stands for ``zero''.
+a zero byte.  The ``z'' in @samp{.asciz} stands for ``zero''.  Note that
+multiple string arguments not separated by commas will be concatenated
+together and only one final zero byte will be stored.
 
 @node Attach_to_group
 @section @code{.attach_to_group @var{name}}

gas/read.c

@@ -5468,6 +5468,11 @@ stringer (int bits_appendzero)
 	  while (is_a_char (c = next_char_of_string ()))
 	    stringer_append_char (c, bitsize);
 
+	  /* Treat "a" "b" as "ab".  Even if we are appending zeros.  */
+	  SKIP_ALL_WHITESPACE ();
+	  if (*input_line_pointer == '"')
+	    break;
+
 	  if (append_zero)
 	    stringer_append_char (0, bitsize);
 

gas/testsuite/gas/all/asciz.d

@@ -0,0 +1,10 @@
+#objdump: -s -j .data -j "\$DATA\$"
+#name: Generation of NUL terminated strings
+# The TIC4x and TIC5x assemblers do not support the concatenation of space separated strings.
+#xfail: tic4*-* tic5*-*
+
+.*: +file format .*
+
+Contents of section (\.data|\$DATA\$):
+.*ab\.cd\..*
+#pass

gas/testsuite/gas/all/asciz.s

@@ -0,0 +1,2 @@
+	.data
+	.asciz "a" "b", "c"   "d"

gas/testsuite/gas/all/gas.exp

@@ -473,3 +473,4 @@ run_dump_test "fill-1"
 gas_test "pr23938.s" "" "" ".xstabs"
 
 run_dump_test "nop"
+run_dump_test "asciz"