genoutput.c (process_template): Process '*' in '@' alternatives.

	* genoutput.c (process_template): Process '*' in '@' alternatives.
	* doc/md.texi (node Output Statement): Provide example for the above.

From-SVN: r192457

gcc/ChangeLog

+2012-10-15  J"orn Rennecke  <joern.rennecke@arc.com>
+
+	* genoutput.c (process_template): Process '*' in '@' alternatives.
+	* doc/md.texi (node Output Statement): Provide example for the above.
+
 2012-10-15  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/54920

gcc/doc/md.texi

@@ -665,6 +665,22 @@ as follows, having the output control string start with a @samp{@@}:
 @end group
 @end smallexample
 
+If you just need a little bit of C code in one (or a few) alternatives,
+you can use @samp{*} inside of a @samp{@@} multi-alternative template:
+
+@smallexample
+@group
+(define_insn ""
+  [(set (match_operand:SI 0 "general_operand" "=r,<,m")
+        (const_int 0))]
+  ""
+  "@@
+   clrreg %0
+   * return stack_mem_p (operands[0]) ? \"push 0\" : \"clrmem %0\";
+   clrmem %0")
+@end group
+@end smallexample
+
 @node Predicates
 @section Predicates
 @cindex predicates

gcc/genoutput.c

 /* Generate code from to output assembler insns as recognized from rtl.
    Copyright (C) 1987, 1988, 1992, 1994, 1995, 1997, 1998, 1999, 2000, 2002,
-   2003, 2004, 2005, 2007, 2008, 2009, 2010, 2012
+   2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011, 2012
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -662,19 +662,55 @@ process_template (struct data *d, const char *template_code)
      list of assembler code templates, one for each alternative.  */
   else if (template_code[0] == '@')
     {
-      d->template_code = 0;
-      d->output_format = INSN_OUTPUT_FORMAT_MULTI;
+      int found_star = 0;
 
-      printf ("\nstatic const char * const output_%d[] = {\n", d->code_number);
+      for (cp = &template_code[1]; *cp; )
+	{
+	  while (ISSPACE (*cp))
+	    cp++;
+	  if (*cp == '*')
+	    found_star = 1;
+	  while (!IS_VSPACE (*cp) && *cp != '\0')
+	    ++cp;
+	}
+      d->template_code = 0;
+      if (found_star)
+	{
+	  d->output_format = INSN_OUTPUT_FORMAT_FUNCTION;
+	  puts ("\nstatic const char *");
+	  printf ("output_%d (rtx *operands ATTRIBUTE_UNUSED, "
+		  "rtx insn ATTRIBUTE_UNUSED)\n", d->code_number);
+	  puts ("{");
+	  puts ("  switch (which_alternative)\n    {");
+	}
+      else
+	{
+	  d->output_format = INSN_OUTPUT_FORMAT_MULTI;
+	  printf ("\nstatic const char * const output_%d[] = {\n",
+		  d->code_number);
+	}
 
       for (i = 0, cp = &template_code[1]; *cp; )
 	{
-	  const char *ep, *sp;
+	  const char *ep, *sp, *bp;
 
 	  while (ISSPACE (*cp))
 	    cp++;
 
-	  printf ("  \"");
+	  bp = cp;
+	  if (found_star)
+	    {
+	      printf ("    case %d:", i);
+	      if (*cp == '*')
+		{
+		  printf ("\n      ");
+		  cp++;
+		}
+	      else
+		printf (" return \"");
+	    }
+	  else
+	    printf ("  \"");
 
 	  for (ep = sp = cp; !IS_VSPACE (*ep) && *ep != '\0'; ++ep)
 	    if (!ISSPACE (*ep))
@@ -690,7 +726,18 @@ process_template (struct data *d, const char *template_code)
 	      cp++;
 	    }
 
-	  printf ("\",\n");
+	  if (!found_star)
+	    puts ("\",");
+	  else if (*bp != '*')
+	    puts ("\";");
+	  else
+	    {
+	      /* The usual action will end with a return.
+		 If there is neither break or return at the end, this is
+		 assumed to be intentional; this allows to have multiple
+		 consecutive alternatives share some code.  */
+	      puts ("");
+	    }
 	  i++;
 	}
       if (i == 1)
@@ -700,7 +747,10 @@ process_template (struct data *d, const char *template_code)
 	error_with_line (d->lineno,
 			 "wrong number of alternatives in the output template");
 
-      printf ("};\n");
+      if (found_star)
+	puts ("      default: gcc_unreachable ();\n    }\n}");
+      else
+	printf ("};\n");
     }
   else
     {