Add --hash-size switch to the linker

6 files changed, 67 insertions, 5 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 38bbbe7..46e4865 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,18 @@
+2004-05-21  Andy Chittenden  <achittenden@bluearc.com>
+
+	* ld.h (ld_config_type): Add new field: hash_table_size.
+	* ldmain.c: Initialise the new field to zero.  If it is non-zero
+	after parsing the linker's command line call
+	bfd_hash_set_default_size.
+	* lexsup.c (option_values): Add OPTION_HASH_SIZE.
+	(ld_options): Add hash-size.
+	(parse_args): Parse --hash-size option.  Allow
+	--reduce-memory-overheads to set the default hash table size as
+	well.
+	* ld.texinfo: Document the new switch.  Also mention that
+	--reduce-memory-overheads can affect the hash table size.
+	* NEWS: Mention the new feature.
+
 2004-05-19  J"orn Rennecke <joern.rennecke@superh.com>
 
 	* NEWS: Mention new linker map file generation and the
diff --git a/ld/NEWS b/ld/NEWS
index a33c6dc..1d07084 100644
--- a/ld/NEWS
+++ b/ld/NEWS
@@ -1,11 +1,19 @@
 -*- text -*-
 
+* A new linker command line switch has been added which allows the hash table
+  size to be set to a suitable prime value near to its argument.  This switch
+  is --hash-size=<NUMBER>.  Also if the switch --reduce-memory-overheads is
+  used, and --hash-size has not been used, then the default value will be set
+  to 1021.
+
 * Linker map files are now generated with an O(N) algorithm for finding symbols
   that are defined in each section.  This uses about 40% more memory for
   symbols than the old O(N^2) algorithm.  You can use the new
   --reduce-memory-overheads option to select the old algorithm; this option
   might also be used in the future to select similar tradeoffs.
 
+Changes in 2.15:
+  
 * New PE --large-address-aware option to indicate executables support virtual
   addresses greater than 2 gigabytes.
 
diff --git a/ld/ld.h b/ld/ld.h
index 1061c35..2bcf7d2 100644
--- a/ld/ld.h
+++ b/ld/ld.h
@@ -1,5 +1,5 @@
 /* ld.h -- general linker header file
-   Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002
+   Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2004
    Free Software Foundation, Inc.
 
    This file is part of GLD, the Gnu Linker.
@@ -241,6 +241,9 @@ typedef struct {
   /* If set, only search library directories explicitly selected
      on the command line.  */
   bfd_boolean only_cmd_line_lib_dirs;
+
+  /* The size of the hash table to use.  */
+  bfd_size_type hash_table_size;
 } ld_config_type;
 
 extern ld_config_type config;
diff --git a/ld/ld.texinfo b/ld/ld.texinfo
index b78d1b0..db87e3f 100644
--- a/ld/ld.texinfo
+++ b/ld/ld.texinfo
@@ -1734,13 +1734,27 @@ If you specify @option{--disable-new-dtags}, no new dynamic tags will be
 created. By default, the new dynamic tags are not created. Note that
 those options are only available for ELF systems.
 
+@kindex --hash-size=@var{number}
+Set the default size of the linker's hash tables to a prime number
+close to @var{number}.  Increasing this value can reduce the length of
+time it takes the linker to perform its tasks, at the expense of
+increasing the linker's memory requirements.  Similarly reducing this
+value can reduce the memory requirements at the expense of speed.
+
 @kindex --reduce-memory-overheads
 @item --reduce-memory-overheads
 This option reduces memory requirements at ld runtime, at the expense of
 linking speed.  This was introduced to to select the old O(n^2) algorithm
 for link map file generation, rather than the new O(n) algorithm which uses
-about 40% more memory for symbol storage.  It may be also be used for
-similar such tradeoffs in the future.
+about 40% more memory for symbol storage.
+
+Another affect of the switch is to set the default hash table size to
+1021, which again saves memory at the cost of lengthening the linker's
+run time.  This is not done however if the *option{--hash-size} switch
+has been used.
+
+The @option{--reduce-memory-overheads} switch may be also be used to
+enable other tradeoffs in future versions of the linker.
 
 @end table
 
diff --git a/ld/ldmain.c b/ld/ldmain.c
index f3df44f..f1804c4 100644
--- a/ld/ldmain.c
+++ b/ld/ldmain.c
@@ -267,6 +267,7 @@ main (int argc, char **argv)
   config.has_shared = FALSE;
   config.split_by_reloc = (unsigned) -1;
   config.split_by_file = (bfd_size_type) -1;
+  config.hash_table_size = 0;
   command_line.force_common_definition = FALSE;
   command_line.inhibit_common_definition = FALSE;
   command_line.interpreter = NULL;
@@ -344,6 +345,9 @@ main (int argc, char **argv)
   lang_has_input_file = FALSE;
   parse_args (argc, argv);
 
+  if (config.hash_table_size != 0)
+    bfd_hash_set_default_size (config.hash_table_size);
+
   ldemul_set_symbols ();
 
   if (link_info.relocatable)
diff --git a/ld/lexsup.c b/ld/lexsup.c
index fcca4d3..5137341 100644
--- a/ld/lexsup.c
+++ b/ld/lexsup.c
@@ -118,6 +118,7 @@ enum option_values
   OPTION_FORCE_EXE_SUFFIX,
   OPTION_GC_SECTIONS,
   OPTION_NO_GC_SECTIONS,
+  OPTION_HASH_SIZE,
   OPTION_CHECK_SECTIONS,
   OPTION_NO_CHECK_SECTIONS,
   OPTION_NO_UNDEFINED,
@@ -328,6 +329,8 @@ static const struct ld_option ld_options[] =
   { {"no-gc-sections", no_argument, NULL, OPTION_NO_GC_SECTIONS},
       '\0', NULL, N_("Don't remove unused sections (default)"),
       TWO_DASHES },
+  { {"hash-size=<NUMBER>", required_argument, NULL, OPTION_HASH_SIZE},
+      '\0', NULL, N_("Set default hash table size close to <NUMBER>"), TWO_DASHES },
   { {"help", no_argument, NULL, OPTION_HELP},
       '\0', NULL, N_("Print option help"), TWO_DASHES },
   { {"init", required_argument, NULL, OPTION_INIT},
@@ -364,6 +367,8 @@ static const struct ld_option ld_options[] =
       '\0', N_("TARGET"), N_("Specify target of output file"), EXACTLY_TWO_DASHES },
   { {"qmagic", no_argument, NULL, OPTION_IGNORE},
       '\0', NULL, N_("Ignored for Linux compatibility"), ONE_DASH },
+  { {"reduce-memory-overheads", no_argument, NULL, OPTION_REDUCE_MEMORY_OVERHEADS},
+      '\0', NULL, N_("Reduce memory overheads, possibly taking much longer"), TWO_DASHES },
   { {"relax", no_argument, NULL, OPTION_RELAX},
       '\0', NULL, N_("Relax branches on certain targets"), TWO_DASHES },
   { {"retain-symbols-file", required_argument, NULL,
@@ -447,8 +452,6 @@ static const struct ld_option ld_options[] =
       '\0', NULL, N_("Always set DT_NEEDED for following dynamic libs"), TWO_DASHES },
   { {"wrap", required_argument, NULL, OPTION_WRAP},
       '\0', N_("SYMBOL"), N_("Use wrapper functions for SYMBOL"), TWO_DASHES },
-  { {"reduce-memory-overheads", no_argument, NULL, OPTION_REDUCE_MEMORY_OVERHEADS},
-      '\0', NULL, N_("reduce memory overheads, possibly taking much longer"), TWO_DASHES },
 };
 
 #define OPTION_COUNT ARRAY_SIZE (ld_options)
@@ -1224,9 +1227,24 @@ parse_args (unsigned argc, char **argv)
 	case OPTION_FINI:
 	  link_info.fini_function = optarg;
 	  break;
+
 	case OPTION_REDUCE_MEMORY_OVERHEADS:
 	  command_line.reduce_memory_overheads = TRUE;
+	  if (config.hash_table_size == 0)
+	    config.hash_table_size = 1021;
 	  break;
+
+        case OPTION_HASH_SIZE:
+	  {
+	    bfd_size_type new_size;
+
+            new_size = strtoul (optarg, NULL, 0);
+            if (new_size)
+              config.hash_table_size = new_size;
+            else
+              einfo (_("%P%X: --hash-size needs a numeric argument\n"));
+          }
+          break;
 	}
     }