PING^2: [PATCH] Support -fuse-ld=bfd and -fuse-ld=gold

PING^2: [PATCH] Support -fuse-ld=bfd and -fuse-ld=gold

[H.J. Lu]

On Fri, Dec 7, 2012 at 5:15 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Wed, Nov 28, 2012 at 8:18 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>
>> Binutils supports 2 linkers, ld.gold and ld.bfd.  One of them is
>> configured as the default linker, ld, which is used by GCC.  Sometimes,
>> we want to use the alternate linker with GCC at run-time.  This patch
>> adds -fuse-ld=bfd and -fuse-ld=gold options to GCC driver.  It changes
>> collect2.c to pick either ld.bfd or ld.gold.  It also adds
>> ORIGINAL_LD_BFD_FOR_TARGET and ORIGINAL_LD_GOLD_FOR_TARGET to
>> exec-tool.in to add -fuse-ld=bfd and -fuse-ld=gold support to
>> collect-ld.  Since ld.bfd nor ld.gold know the new options, you
>> will get
>>
>> # ./xgcc -B./  /tmp/x.c -fuse-ld=gold -v
>> ...
>> ./collect-ld --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -fuse-ld=gold /lib/../lib64/crt1.o /lib/../lib64/crti.o ./crtbegin.o -L. -L/lib/../lib64 -L/usr/lib/../lib64 /tmp/cclVWcGz.o -v -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed ./crtend.o /lib/../lib64/crtn.o
>> GNU gold (Linux/GNU Binutils 2.23.51.0.7.20121127) 1.11
>> /usr/local/bin/ld.gold: fatal error: -f/--auxiliary may not be used without -shared
>> collect2: error: ld returned 1 exit status
>>
>> This is because we pass everything to ld and ld.bfd/ld.gold doesn't
>> understand -fuse-ld=bfd/-fuse-ld=gold.  It isn't a problem for collect2
>> since it will filter-out -fuse-ld=bfd/-fuse-ld=gold.  I will submit a
>> binutils patch to ignore -fuse-ld=bfd/-fuse-ld=gold, similar to -flto
>> options.
>>
>> OK to install?
>>
>> Thanks.
>>
>>
>> H.J.
>> ---
>> 2012-11-28   Nick Clifton  <nickc@redhat.com>
>>              Matthias Klose <doko@debian.org>
>>              Doug Kwan  <dougkwan@google.com>
>>              H.J. Lu  <hongjiu.lu@intel.com>
>>
>>         PR driver/55470
>>         * collect2.c (main): Support -fuse-ld=bfd and -fuse-ld=gold.
>>
>>         * common.opt: Add fuse-ld=bfd and fuse-ld=gold.
>>
>>         * gcc.c (LINK_COMMAND_SPEC): Pass -fuse-ld=* to collect2.
>>
>>         * opts.c (comman_handle_option): Ignore -fuse-ld=bfd and
>>         -fuse-ld=gold.
>>
>>         * doc/invoke.texi: Document -fuse-ld=bfd and -fuse-ld=gold.
>
> Here is the minimum patch for 4.8.  OK to install?
>
>

Hi Joseph,

Can you review this?

Thanks.


H.J.

Re: PING^2: [PATCH] Support -fuse-ld=bfd and -fuse-ld=gold

[Joseph S. Myers]

On Thu, 13 Dec 2012, H.J. Lu wrote:

> Hi Joseph,
> 
> Can you review this?

I'm still confused as to what's supposed to be reviewed and whether the 
issues raised in the previous discussions have been properly addressed.  
Looking at <http://gcc.gnu.org/ml/gcc-patches/2012-12/msg00484.html>, I 
don't see the need for the variables named with Var in common.opt, and I'd 
think proper help text would be better than using Undocumented.

-- 
Joseph S. Myers
joseph@codesourcery.com

Re: PING^2: [PATCH] Support -fuse-ld=bfd and -fuse-ld=gold

[H.J. Lu]

[-- Attachment #1: Type: text/plain, Size: 1103 bytes --]

On Wed, Dec 19, 2012 at 1:13 PM, Joseph S. Myers
<joseph@codesourcery.com> wrote:
> On Thu, 13 Dec 2012, H.J. Lu wrote:
>
>> Hi Joseph,
>>
>> Can you review this?
>
> I'm still confused as to what's supposed to be reviewed and whether the
> issues raised in the previous discussions have been properly addressed.
> Looking at <http://gcc.gnu.org/ml/gcc-patches/2012-12/msg00484.html>, I
> don't see the need for the variables named with Var in common.opt, and I'd

Fixed.

> think proper help text would be better than using Undocumented.
>

Fixed.

Here is the updated patch.  OK for trunk?

Thanks.

-- 
H.J.
--
2012-12-19   Nick Clifton  <nickc@redhat.com>
	     Matthias Klose <doko@debian.org>
	     Doug Kwan  <dougkwan@google.com>
	     H.J. Lu  <hongjiu.lu@intel.com>

	PR driver/55470
	* collect2.c (main): Support -fuse-ld=bfd and -fuse-ld=gold.

	* common.opt: Add fuse-ld=bfd and fuse-ld=gold.

	* gcc.c (LINK_COMMAND_SPEC): Pass -fuse-ld=* to collect2.

	* opts.c (comman_handle_option): Ignore -fuse-ld=bfd and
	-fuse-ld=gold.

	* doc/invoke.texi: Document -fuse-ld=bfd and -fuse-ld=gold.

[-- Attachment #2: 0001-Support-fuse-ld-bfd-and-fuse-ld-gold.patch --]
[-- Type: application/octet-stream, Size: 8759 bytes --]

From f9959dba850b9895775f13cd66b5372863ef3aff Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 19 Dec 2012 14:17:44 -0800
Subject: [PATCH] Support -fuse-ld=bfd and -fuse-ld=gold

---
 gcc/collect2.c      | 68 +++++++++++++++++++++++++++++++++++++----------------
 gcc/common.opt      |  8 +++++++
 gcc/doc/invoke.texi |  8 ++++++-
 gcc/gcc.c           |  3 ++-
 gcc/opts.c          |  2 ++
 6 files changed, 83 insertions(+), 22 deletions(-)
 create mode 100644 gcc/ChangeLog.gold

2012-12-19   Nick Clifton  <nickc@redhat.com>
	     Matthias Klose <doko@debian.org>
	     Doug Kwan  <dougkwan@google.com>
	     H.J. Lu  <hongjiu.lu@intel.com>

	PR driver/55470
	* collect2.c (main): Support -fuse-ld=bfd and -fuse-ld=gold.

	* common.opt: Add fuse-ld=bfd and fuse-ld=gold.

	* gcc.c (LINK_COMMAND_SPEC): Pass -fuse-ld=* to collect2.

	* opts.c (comman_handle_option): Ignore -fuse-ld=bfd and
	-fuse-ld=gold.

	* doc/invoke.texi: Document -fuse-ld=bfd and -fuse-ld=gold.
diff --git a/gcc/collect2.c b/gcc/collect2.c
index 49c4030..4e8cdf0 100644
--- a/gcc/collect2.c
+++ b/gcc/collect2.c
@@ -842,8 +842,21 @@ maybe_run_lto_and_relink (char **lto_ld_argv, char **object_lst,
 int
 main (int argc, char **argv)
 {
-  static const char *const ld_suffix	= "ld";
-  static const char *const plugin_ld_suffix = PLUGIN_LD_SUFFIX;
+  enum linker_select
+    {
+      USE_DEFAULT_LD,
+      USE_PLUGIN_LD,
+      USE_GOLD_LD,
+      USE_BFD_LD,
+      USE_LD_MAX
+    } selected_linker = USE_DEFAULT_LD;
+  static const char *const ld_suffixes[USE_LD_MAX] =
+    {
+      "ld",
+      PLUGIN_LD_SUFFIX,
+      "ld.gold",
+      "ld.bfd"
+    };
   static const char *const real_ld_suffix = "real-ld";
   static const char *const collect_ld_suffix = "collect-ld";
   static const char *const nm_suffix	= "nm";
@@ -854,16 +867,13 @@ main (int argc, char **argv)
   static const char *const strip_suffix = "strip";
   static const char *const gstrip_suffix = "gstrip";
 
+  const char *full_ld_suffixes[USE_LD_MAX];
 #ifdef CROSS_DIRECTORY_STRUCTURE
   /* If we look for a program in the compiler directories, we just use
      the short name, since these directories are already system-specific.
      But it we look for a program in the system directories, we need to
      qualify the program name with the target machine.  */
 
-  const char *const full_ld_suffix =
-    concat(target_machine, "-", ld_suffix, NULL);
-  const char *const full_plugin_ld_suffix =
-    concat(target_machine, "-", plugin_ld_suffix, NULL);
   const char *const full_nm_suffix =
     concat (target_machine, "-", nm_suffix, NULL);
   const char *const full_gnm_suffix =
@@ -877,13 +887,11 @@ main (int argc, char **argv)
   const char *const full_gstrip_suffix =
     concat (target_machine, "-", gstrip_suffix, NULL);
 #else
-  const char *const full_ld_suffix	= ld_suffix;
-  const char *const full_plugin_ld_suffix = plugin_ld_suffix;
-  const char *const full_nm_suffix	= nm_suffix;
-  const char *const full_gnm_suffix	= gnm_suffix;
 #ifdef LDD_SUFFIX
   const char *const full_ldd_suffix	= ldd_suffix;
 #endif
+  const char *const full_nm_suffix	= nm_suffix;
+  const char *const full_gnm_suffix	= gnm_suffix;
   const char *const full_strip_suffix	= strip_suffix;
   const char *const full_gstrip_suffix	= gstrip_suffix;
 #endif /* CROSS_DIRECTORY_STRUCTURE */
@@ -900,6 +908,7 @@ main (int argc, char **argv)
   char **ld1_argv;
   const char **ld1;
   bool use_plugin = false;
+  bool use_collect_ld = false;
 
   /* The kinds of symbols we will have to consider when scanning the
      outcome of a first pass link.  This is ALL to start with, then might
@@ -919,6 +928,15 @@ main (int argc, char **argv)
   int first_file;
   int num_c_args;
   char **old_argv;
+  int i;
+
+  for (i = 0; i < USE_LD_MAX; i++)
+    full_ld_suffixes[i]
+#ifdef CROSS_DIRECTORY_STRUCTURE
+      = concat(target_machine, "-", ld_suffixes[i], NULL);
+#else
+      = ld_suffixes[i];
+#endif
 
   p = argv[0] + strlen (argv[0]);
   while (p != argv[0] && !IS_DIR_SEPARATOR (p[-1]))
@@ -980,7 +998,6 @@ main (int argc, char **argv)
      are called.  We also look for the -flto or -flto-partition=none flag to know
      what LTO mode we are in.  */
   {
-    int i;
     bool no_partition = false;
 
     for (i = 1; argv[i] != NULL; i ++)
@@ -998,7 +1015,14 @@ main (int argc, char **argv)
 	  {
 	    use_plugin = true;
 	    lto_mode = LTO_MODE_NONE;
+	    if (selected_linker == USE_DEFAULT_LD)
+	      selected_linker = USE_PLUGIN_LD;
 	  }
+	else if (strcmp (argv[i], "-fuse-ld=bfd") == 0)
+	  selected_linker = USE_BFD_LD;
+	else if (strcmp (argv[i], "-fuse-ld=gold") == 0)
+	  selected_linker = USE_GOLD_LD;
+
 #ifdef COLLECT_EXPORT_LIST
 	/* since -brtl, -bexport, -b64 are not position dependent
 	   also check for them here */
@@ -1095,21 +1119,18 @@ main (int argc, char **argv)
   ld_file_name = find_a_file (&cpath, real_ld_suffix);
   /* Likewise for `collect-ld'.  */
   if (ld_file_name == 0)
-    ld_file_name = find_a_file (&cpath, collect_ld_suffix);
+    {
+      ld_file_name = find_a_file (&cpath, collect_ld_suffix);
+      use_collect_ld = ld_file_name != 0;
+    }
   /* Search the compiler directories for `ld'.  We have protection against
      recursive calls in find_a_file.  */
   if (ld_file_name == 0)
-    ld_file_name = find_a_file (&cpath,
-				use_plugin
-				? plugin_ld_suffix
-				: ld_suffix);
+    ld_file_name = find_a_file (&cpath, ld_suffixes[selected_linker]);
   /* Search the ordinary system bin directories
      for `ld' (if native linking) or `TARGET-ld' (if cross).  */
   if (ld_file_name == 0)
-    ld_file_name = find_a_file (&path,
-				use_plugin
-				? full_plugin_ld_suffix
-				: full_ld_suffix);
+    ld_file_name = find_a_file (&path, full_ld_suffixes[selected_linker]);
 
 #ifdef REAL_NM_FILE_NAME
   nm_file_name = find_a_file (&path, REAL_NM_FILE_NAME);
@@ -1266,6 +1287,13 @@ main (int argc, char **argv)
 			 "configuration");
 #endif
 		}
+	      else if (!use_collect_ld
+		       && strncmp (arg, "-fuse-ld=", 9) == 0)
+		{
+		  /* Do not pass -fuse-ld={bfd|gold} to the linker. */
+		  ld1--;
+		  ld2--;
+		}
 #ifdef TARGET_AIX_VERSION
 	      else
 		{
diff --git a/gcc/common.opt b/gcc/common.opt
index 4c8bd11..8085f64 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2171,6 +2171,14 @@ funwind-tables
 Common Report Var(flag_unwind_tables) Optimization
 Just generate unwind tables for exception handling
 
+fuse-ld=bfd
+Common Negative(fuse-ld=gold)
+Use the bfd linker instead of the default linker
+
+fuse-ld=gold
+Common Negative(fuse-ld=bfd)
+Use the gold linker instead of the default linker
+
 fuse-linker-plugin
 Common Undocumented
 
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 06ba770..df53766 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -425,7 +425,7 @@ Objective-C and Objective-C++ Dialects}.
 -funit-at-a-time -funroll-all-loops -funroll-loops @gol
 -funsafe-loop-optimizations -funsafe-math-optimizations -funswitch-loops @gol
 -fvariable-expansion-in-unroller -fvect-cost-model -fvpt -fweb @gol
--fwhole-program -fwpa -fuse-linker-plugin @gol
+-fwhole-program -fwpa -fuse-ld=@var{linker} -fuse-linker-plugin @gol
 --param @var{name}=@var{value}
 -O  -O0  -O1  -O2  -O3  -Os -Ofast -Og}
 
@@ -8409,6 +8409,12 @@ the comparison operation before register allocation is complete.
 
 Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
 
+@item -fuse-ld=bfd
+Use the @command{bfd} linker instead of the default linker.
+
+@item -fuse-ld=gold
+Use the @command{gold} linker instead of the default linker.
+
 @item -fcprop-registers
 @opindex fcprop-registers
 After register allocation and post-register allocation instruction splitting,
diff --git a/gcc/gcc.c b/gcc/gcc.c
index 13e93e5..e0fee40 100644
--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -705,7 +705,8 @@ proper position among the other output files.  */
     LINK_PLUGIN_SPEC \
     "%{flto|flto=*:%<fcompare-debug*} \
     %{flto} %{flto=*} %l " LINK_PIE_SPEC \
-   "%X %{o*} %{e*} %{N} %{n} %{r}\
+   "%{fuse-ld=*:-fuse-ld=%*}\
+    %X %{o*} %{e*} %{N} %{n} %{r}\
     %{s} %{t} %{u*} %{z} %{Z} %{!nostdlib:%{!nostartfiles:%S}}\
     %{static:} %{L*} %(mfwrap) %(link_libgcc) %o\
     %{fopenmp|ftree-parallelize-loops=*:%:include(libgomp.spec)%(link_gomp)}\
diff --git a/gcc/opts.c b/gcc/opts.c
index b3a9afe..ff1b51e 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -1753,6 +1753,8 @@ common_handle_option (struct gcc_options *opts,
       dc->max_errors = value;
       break;
 
+    case OPT_fuse_ld_bfd:
+    case OPT_fuse_ld_gold:
     case OPT_fuse_linker_plugin:
       /* No-op. Used by the driver and passed to us because it starts with f.*/
       break;
-- 
1.7.11.7

Re: PING^2: [PATCH] Support -fuse-ld=bfd and -fuse-ld=gold

[Joseph S. Myers]

On Wed, 19 Dec 2012, H.J. Lu wrote:

> +#ifdef CROSS_DIRECTORY_STRUCTURE
> +      = concat(target_machine, "-", ld_suffixes[i], NULL);

Missing space before '('.

The patch is OK with that fixed.

-- 
Joseph S. Myers
joseph@codesourcery.com