ld: Add --no-print-map-discarded option

Add a new option to disable the listing of discarded sections
in map file output.  The use case stems from a large application
built with -ffunction-sections --gc-sections where the list of
discarded sections blows up the map file output.  The default
behaviour remains to print discarded sections,  but the new option
allows us to disable it.

ld/
	* NEWS: Mention new option --no-print-map-discarded.
	* ld.h (ld_config_type) <print_map_discarded>: New field.
	* ldlang.c (lang_map): Conditionally output discarded sections
	in map files based on configuration option.
	* ldlex.h (option_values) <OPTION_PRINT_MAP_DISCARDED,
	OPTION_NO_PRINT_MAP_DISCARDED>: New.
	* ldmain.c (main): Enabled print_map_discarded by default.
	* lexsup.c (ld_options): Add new command-line options.
	(parse_args) <OPTION_NO_PRINT_MAP_DISCARDED,
	OPTION_PRINT_MAP_DISCARDED>: New cases.
	* ld.texi: Document new options.
	* testsuite/ld-gc/gc.exp: Add new test.
	* testsuite/ld-gc/skip-map-discarded.s: New file.
	* testsuite/ld-gc/skip-map-discarded.d: New file.
	* testsuite/ld-gc/skip-map-discarded.map: New file.

ld/ChangeLog

@@ -1,3 +1,21 @@
+2019-04-11  Faraz Shahbazker  <fshahbazker@wavecomp.com>
+
+	* NEWS: Mention new option --no-print-map-discarded.
+	* ld.h (ld_config_type) <print_map_discarded>: New field.
+	* ldlang.c (lang_map): Conditionally output discarded sections
+	in map files based on configuration option.
+	* ldlex.h (option_values) <OPTION_PRINT_MAP_DISCARDED,
+	OPTION_NO_PRINT_MAP_DISCARDED>: New.
+	* ldmain.c (main): Enabled print_map_discarded by default.
+	* lexsup.c (ld_options): Add new command-line options.
+	(parse_args) <OPTION_NO_PRINT_MAP_DISCARDED,
+	OPTION_PRINT_MAP_DISCARDED>: New cases.
+	* ld.texi: Document new options.
+	* testsuite/ld-gc/gc.exp: Add new test.
+	* testsuite/ld-gc/skip-map-discarded.s: New file.
+	* testsuite/ld-gc/skip-map-discarded.d: New file.
+	* testsuite/ld-gc/skip-map-discarded.map: New file.
+
 2019-04-11  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* ld.texi: Document -z cet-report=[none|warning|error].

ld/NEWS

@@ -1,5 +1,7 @@
 -*- text -*-
 
+* Add command-line option --no-print-map-discarded.
+
 Changes in 2.33:
 
 * Add target handlers for AArch64 for ELF GNU program properties.

ld/ld.h

@@ -318,6 +318,9 @@ typedef struct
 
   /* The common page size for ELF.  */
   bfd_vma commonpagesize;
+
+  /* If set, print discarded sections in map file output.  */
+  bfd_boolean print_map_discarded;
 } ld_config_type;
 
 extern ld_config_type config;

ld/ld.texi

@@ -783,6 +783,14 @@ when merging properties in  @file{foo.o}, whose 0xc0010001 property value
 is 0x1, and @file{bar.o}, whose 0xc0010001 property value is 0x1.
 @end itemize
 
+@cindex link map discarded
+@kindex --print-map-discarded
+@kindex --no-print-map-discarded
+@item --print-map-discarded
+@itemx --no-print-map-discarded
+Print (or do not print) the list of discarded and garbage collected sections
+in the link map.  Enabled by default.
+
 @kindex -n
 @cindex read-only text
 @cindex NMAGIC

ld/ldlang.c

@@ -2251,19 +2251,20 @@ lang_map (void)
 	  || file->flags.just_syms)
 	continue;
 
-      for (s = file->the_bfd->sections; s != NULL; s = s->next)
-	if ((s->output_section == NULL
-	     || s->output_section->owner != link_info.output_bfd)
-	    && (s->flags & (SEC_LINKER_CREATED | SEC_KEEP)) == 0)
-	  {
-	    if (!dis_header_printed)
-	      {
-		fprintf (config.map_file, _("\nDiscarded input sections\n\n"));
-		dis_header_printed = TRUE;
-	      }
+      if (config.print_map_discarded)
+	for (s = file->the_bfd->sections; s != NULL; s = s->next)
+	  if ((s->output_section == NULL
+	       || s->output_section->owner != link_info.output_bfd)
+	      && (s->flags & (SEC_LINKER_CREATED | SEC_KEEP)) == 0)
+	    {
+	      if (! dis_header_printed)
+		{
+		  fprintf (config.map_file, _("\nDiscarded input sections\n\n"));
+		  dis_header_printed = TRUE;
+		}
 
-	    print_input_section (s, TRUE);
-	  }
+	      print_input_section (s, TRUE);
+	    }
     }
 
   minfo (_("\nMemory Configuration\n\n"));

ld/ldlex.h

@@ -148,6 +148,8 @@ enum option_values
   OPTION_REQUIRE_DEFINED_SYMBOL,
   OPTION_ORPHAN_HANDLING,
   OPTION_FORCE_GROUP_ALLOCATION,
+  OPTION_PRINT_MAP_DISCARDED,
+  OPTION_NO_PRINT_MAP_DISCARDED,
 };
 
 /* The initial parser states.  */

ld/ldmain.c

@@ -264,6 +264,7 @@ main (int argc, char **argv)
   config.make_executable = TRUE;
   config.magic_demand_paged = TRUE;
   config.text_read_only = TRUE;
+  config.print_map_discarded = TRUE;
   link_info.disable_target_specific_optimizations = -1;
 
   command_line.warn_mismatch = TRUE;

ld/lexsup.c

@@ -543,6 +543,12 @@ static const struct ld_option ld_options[] =
   { {"orphan-handling", required_argument, NULL, OPTION_ORPHAN_HANDLING},
     '\0', N_("=MODE"), N_("Control how orphan sections are handled."),
     TWO_DASHES },
+  { {"print-map-discarded", no_argument, NULL, OPTION_PRINT_MAP_DISCARDED},
+    '\0', NULL, N_("Show discarded sections in map file output (default)"),
+    TWO_DASHES },
+  { {"no-print-map-discarded", no_argument, NULL, OPTION_NO_PRINT_MAP_DISCARDED},
+    '\0', NULL, N_("Do not show discarded sections in map file output"),
+    TWO_DASHES },
 };
 
 #define OPTION_COUNT ARRAY_SIZE (ld_options)
@@ -1577,6 +1583,14 @@ parse_args (unsigned argc, char **argv)
 	    einfo (_("%F%P: invalid argument to option"
 		     " \"--orphan-handling\"\n"));
 	  break;
+
+	case OPTION_NO_PRINT_MAP_DISCARDED:
+	  config.print_map_discarded = FALSE;
+	  break;
+
+	case OPTION_PRINT_MAP_DISCARDED:
+	  config.print_map_discarded = TRUE;
+	  break;
 	}
     }
 

ld/testsuite/ld-gc/gc.exp

@@ -171,3 +171,5 @@ if { [is_elf_format] && [check_shared_lib_support] \
     ]
     run_dump_test "pr20306"
 }
+
+run_dump_test "skip-map-discarded"

ld/testsuite/ld-gc/skip-map-discarded.d

@@ -0,0 +1,3 @@
+#name: Check --no-print-map-discarded linker option
+#ld: -e 0 --gc-sections --no-print-map-discarded
+#map: skip-map-discarded.map

ld/testsuite/ld-gc/skip-map-discarded.map

@@ -0,0 +1,5 @@
+#failif
+Discarded input sections
+#...
+ _foo.*
+#...

ld/testsuite/ld-gc/skip-map-discarded.s

@@ -0,0 +1,5 @@
+.globl __start
+__start:
+	.section	_foo
+foo:
+	.long	1