common.opt: Add fmerge-debug-strings.

./:	* common.opt: Add fmerge-debug-strings.
	* dwarf2out.c (DEBUG_STR_SECTION_FLAGS): Test
	flag_merge_debug_strings rather than flag_merge_constants.
	* doc/invoke.texi (Option Summary): Mention
	-fmerge-debug-strings.
	(Debugging Options): Document -fmerge-debug-strings.
testsuite/:
	* gcc.dg/debug/dwarf2/var1.c: Add -fno-merge-debug-strings.

From-SVN: r131630

gcc/ChangeLog

 2008-01-18  Ian Lance Taylor  <iant@google.com>
 
+	* common.opt: Add fmerge-debug-strings.
+	* dwarf2out.c (DEBUG_STR_SECTION_FLAGS): Test
+	flag_merge_debug_strings rather than flag_merge_constants.
+	* doc/invoke.texi (Option Summary): Mention
+	-fmerge-debug-strings.
+	(Debugging Options): Document -fmerge-debug-strings.
+
+2008-01-18  Ian Lance Taylor  <iant@google.com>
+
 	PR c++/33407
 	* tree.h (DECL_IS_OPERATOR_NEW): Define.
 	(struct tree_function_decl): Add new field operator_new_flag.

gcc/common.opt

 ; Options for the language- and target-independent parts of the compiler.
 
-; Copyright (C) 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
+; Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008
+; Free Software Foundation, Inc.
 ;
 ; This file is part of GCC.
 ;
@@ -664,6 +665,10 @@ fmerge-constants
 Common Report Var(flag_merge_constants,1) VarExists Optimization
 Attempt to merge identical constants across compilation units
 
+fmerge-debug-strings
+Common Report Var(flag_merge_debug_strings) Init(1)
+Attempt to merge identical debug strings across compilation units
+
 fmessage-length=
 Common RejectNegative Joined UInteger
 -fmessage-length=<number>	Limit diagnostics to <number> characters per line.  0 suppresses line-wrapping

gcc/doc/invoke.texi

 @c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
-@c 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
+@c 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
 @c Free Software Foundation, Inc.
 @c This is part of the GCC manual.
 @c For copying conditions, see the file gcc.texi.
@@ -11,8 +11,8 @@
 
 @c man begin COPYRIGHT
 Copyright @copyright{} 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
-2007 Free Software Foundation, Inc.
+1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+Free Software Foundation, Inc.
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.2 or
@@ -304,7 +304,7 @@ Objective-C and Objective-C++ Dialects}.
 -ftest-coverage  -ftime-report -fvar-tracking @gol
 -g  -g@var{level}  -gcoff -gdwarf-2 @gol
 -ggdb  -gstabs  -gstabs+  -gvms  -gxcoff  -gxcoff+ @gol
--fdebug-prefix-map=@var{old}=@var{new} @gol
+-fmerge-debug-strings -fdebug-prefix-map=@var{old}=@var{new} @gol
 -femit-struct-debug-baseonly -femit-struct-debug-reduced @gol
 -femit-struct-debug-detailed@r{[}=@var{spec-list}@r{]} @gol
 -p  -pg  -print-file-name=@var{library}  -print-libgcc-file-name @gol
@@ -4162,6 +4162,14 @@ The default is @samp{-femit-struct-debug-detailed=all}.
 
 This option works only with DWARF 2.
 
+@item -fmerge-debug-strings
+@opindex fmerge-debug-strings
+Direct the linker to merge together strings which are identical in
+different object files.  This is not supported by all assemblers or
+linker.  This decreases the size of the debug information in the
+output file at the cost of increasing link processing time.  This is
+on by default.
+
 @item -fdebug-prefix-map=@var{old}=@var{new}
 @opindex fdebug-prefix-map
 When compiling files in directory @file{@var{old}}, record debugging

gcc/dwarf2out.c

@@ -4393,7 +4393,7 @@ static int maybe_emit_file (struct dwarf_file_data *fd);
 
 /* Section flags for .debug_str section.  */
 #define DEBUG_STR_SECTION_FLAGS \
-  (HAVE_GAS_SHF_MERGE && flag_merge_constants			\
+  (HAVE_GAS_SHF_MERGE && flag_merge_debug_strings		\
    ? SECTION_DEBUG | SECTION_MERGE | SECTION_STRINGS | 1	\
    : SECTION_DEBUG)
 

gcc/testsuite/ChangeLog

 2008-01-18  Ian Lance Taylor  <iant@google.com>
 
+	* gcc.dg/debug/dwarf2/var1.c: Add -fno-merge-debug-strings.
+
+2008-01-18  Ian Lance Taylor  <iant@google.com>
+
 	PR c++/33407
 	* g++.dg/init/new26.C: New test.
 

gcc/testsuite/gcc.dg/debug/dwarf2/var1.c

 /* PR 23190 */
 /* { dg-do compile }
-/* { dg-options "-gdwarf-2 -dA" } */
+/* { dg-options "-gdwarf-2 -dA -fno-merge-debug-strings" } */
 /* { dg-final { scan-assembler "xyzzy\[^\\n\\r\]+DW_AT_name" } } */
 
 void f(void)