New option for position-independent code.

ChangeLog

@@ -1,3 +1,20 @@
+2002-12-10  Bruno Haible  <bruno@clisp.org>
+
+	* src/options.h (SHAREDLIB): New enum value.
+	* src/options.cc (Options::short_usage): Mention option -P.
+	(Options::long_usage): Document option -P.
+	(long_options): Add option --pic.
+	(Options::parse_options): Handle option -P/--pic.
+	* src/output.cc (output_keyword_blank_entries): When SHAREDLIB is
+	specified, emit NULL pointers instead of "".
+	(Output::output_lookup_function_body): When SHAREDLIB is specified
+	and SWITCH and DUP and not specified, test the table entry against
+	NULL before the string comparison.
+	* tests/test-6.exp: Update.
+	* doc/gperf.texi (Output Details): Document option -P.
+	* NEWS: Update.
+	Suggested by Ulrich Drepper.
+
 2002-12-08  Bruno Haible  <bruno@clisp.org>
 
 	* tests/permut2.gperf, tests/permut2.exp: New files.

NEWS

@@ -1,4 +1,4 @@
-New in 2.96:
+New in 2.97:
 
 * Added option --output that allows to specify the output file name.
 * Some options have been renamed:
@@ -40,6 +40,8 @@ New in 2.96:
   the table's size will grow as needed. Earlier versions of gperf bailed
   out with an "Internal error, duplicate hash code value".
 * The options -f/--fast and -o/--occurrence-sort have no effect any more.
+* Added option -P/--pic that optimizes the generated code for use in shared
+  libraries.
 * Bug fixes.
 
 New in 2.7.2:

doc/gperf.texi

@@ -931,6 +931,13 @@ Generate the static table of keywords as a static global variable,
 rather than hiding it inside of the lookup function (which is the
 default behavior).
 
+@item -P
+@itemx --pic
+Optimize the generated table for inclusion in shared libraries.  This
+reduces the startup time of programs using a shared library containing
+the generated code, at the expense of one more test-and-branch instruction
+at run time.
+
 @item -W @var{hash-table-array-name}
 @itemx --word-array-name=@var{hash-table-array-name}
 @cindex Array name

src/options.cc

@@ -66,7 +66,7 @@ static const char *const DEFAULT_DELIMITERS = ",";
 void
 Options::short_usage (FILE * stream) const
 {
-  fprintf (stream, "Usage: %s [-cCdDef[num]F<initializers>GhH<hashname>i<init>Ij<jump>k<keys>K<keyname>lL<language>m<num>nN<function name>ors<size>S<switches>tTvW<wordlistname>Z<class name>7] [input-file]\n"
+  fprintf (stream, "Usage: %s [-cCdDef[num]F<initializers>GhH<hashname>i<init>Ij<jump>k<keys>K<keyname>lL<language>m<num>nN<function name>oPrs<size>S<switches>tTvW<wordlistname>Z<class name>7] [input-file]\n"
            "Try '%s --help' for more information.\n",
            program_name, program_name);
 }
@@ -158,6 +158,10 @@ Options::long_usage (FILE * stream) const
            "  -G, --global-table     Generate the static table of keywords as a static\n"
            "                         global variable, rather than hiding it inside of the\n"
            "                         lookup function (which is the default behavior).\n");
+  fprintf (stream,
+           "  -P, --pic              Optimize the generated table for inclusion in shared\n"
+           "                         libraries.  This reduces the startup time of programs\n"
+           "                         using a shared library containing the generated code.\n");
   fprintf (stream,
            "  -W, --word-array-name=NAME\n"
            "                         Specify name of word list array. Default name is\n"
@@ -631,6 +635,7 @@ static const struct option long_options[] =
   { "no-strlen", no_argument, NULL, 'n' },
   { "occurrence-sort", no_argument, NULL, 'o' },
   { "optimized-collision-resolution", no_argument, NULL, 'O' },
+  { "pic", no_argument, NULL, 'P' },
   { "random", no_argument, NULL, 'r' },
   { "size-multiple", required_argument, NULL, 's' },
   { "help", no_argument, NULL, 'h' },
@@ -650,7 +655,7 @@ Options::parse_options (int argc, char *argv[])
 
   while ((option_char =
             getopt_long (_argument_count, _argument_vector,
-                         "acCdDe:Ef:F:gGhH:i:Ij:k:K:lL:m:nN:oOprs:S:tTvW:Z:7",
+                         "acCdDe:Ef:F:gGhH:i:Ij:k:K:lL:m:nN:oOpPrs:S:tTvW:Z:7",
                          long_options, NULL))
          != -1)
     {
@@ -838,6 +843,11 @@ Options::parse_options (int argc, char *argv[])
           break;                /* Not needed any more.  */
         case 'p':               /* Generated lookup function a pointer instead of int. */
           break;                /* This is now the default. */
+        case 'P':               /* Optimize for position-independent code.  */
+          {
+            _option_word |= SHAREDLIB;
+            break;
+          }
         case 'r':               /* Utilize randomness to initialize the associated values table. */
           {
             _option_word |= RANDOM;

src/options.h

@@ -95,7 +95,10 @@ enum Option_Type
   INCLUDE      = 1 << 18,
 
   /* Assume 7-bit, not 8-bit, characters.  */
-  SEVENBIT     = 1 << 19
+  SEVENBIT     = 1 << 19,
+
+  /* Optimize for position-independent code.  */
+  SHAREDLIB    = 1 << 20
 };
 
 /* Class manager for gperf program Options. */

src/output.cc

@@ -726,13 +726,14 @@ output_keyword_blank_entries (int count, const char *indent)
   int columns;
   if (option[TYPE])
     {
-      columns = 58 / (6 + strlen (option.get_initializer_suffix()));
+      columns = 58 / (4 + (option[SHAREDLIB] ? 8 : 2)
+                        + strlen (option.get_initializer_suffix()));
       if (columns == 0)
         columns = 1;
     }
   else
     {
-      columns = 9;
+      columns = (option[SHAREDLIB] ? 4 : 9);
     }
   int column = 0;
   for (int i = 0; i < count; i++)
@@ -749,9 +750,13 @@ output_keyword_blank_entries (int count, const char *indent)
             printf (", ");
         }
       if (option[TYPE])
-        printf ("{\"\"%s}", option.get_initializer_suffix());
+        printf ("{");
+      if (option[SHAREDLIB])
+        printf ("(char*)0");
       else
         printf ("\"\"");
+      if (option[TYPE])
+        printf ("%s}", option.get_initializer_suffix());
       column++;
     }
 }
@@ -1362,6 +1367,8 @@ Output::output_lookup_function_body (const Output_Compare& comparison) const
           printf (";\n\n"
                   "%*s  if (",
                   indent, "");
+          if (option[SHAREDLIB])
+            printf ("s && ");
           comparison.output_comparison (Output_Expr1 ("str"), Output_Expr1 ("s"));
           printf (")\n"
                   "%*s    return ",

tests/test-6.exp

@@ -57,6 +57,9 @@ Details in the output code:
   -G, --global-table     Generate the static table of keywords as a static
                          global variable, rather than hiding it inside of the
                          lookup function (which is the default behavior).
+  -P, --pic              Optimize the generated table for inclusion in shared
+                         libraries.  This reduces the startup time of programs
+                         using a shared library containing the generated code.
   -W, --word-array-name=NAME
                          Specify name of word list array. Default name is
                          'wordlist'.