LoongArch ld support

2021-10-22  Chenghua Xu  <xuchenghua@loongson.cn>
	    Zhensong Liu  <liuzhensong@loongson.cn>
	    Weinan Liu  <liuweinan@loongson.cn>
	    Xiaolin Tang  <tangxiaolin@loongson.cn>

ld/
	* Makefile.am: Add LoongArch.
	* NEWS: Mention LoongArch support.
	* configure.tgt: Add LoongArch.
	* emulparams/elf32loongarch-defs.sh: New.
	* emulparams/elf32loongarch.sh: Likewise.
	* emulparams/elf64loongarch-defs.sh: Likewise.
	* emulparams/elf64loongarch.sh: Likewise.
	* emultempl/loongarchelf.em: Likewise.
	* Makefile.in: Regenerate.
	* po/BLD-POTFILES.in: Regenerate.
ld/testsuite/
	* ld-loongarch-elf/disas-jirl.d: New.
	* ld-loongarch-elf/disas-jirl.s: Likewise.
	* ld-loongarch-elf/jmp_op.d: Likewise.
	* ld-loongarch-elf/jmp_op.s: Likewise.
	* ld-loongarch-elf/ld-loongarch-elf.exp: Likewise.
	* ld-loongarch-elf/macro_op.d: Likewise.
	* ld-loongarch-elf/macro_op.s: Likewise.
	* ld-loongarch-elf/syscall-0.s: Likewise.
	* ld-loongarch-elf/syscall-1.s: Likewise.
	* ld-loongarch-elf/syscall.d: Likewise.
	* ld-srec/srec.exp: Add LoongArch.
	* ld-unique/pr21529.d: Likewise.

1 files changed, 87 insertions, 0 deletions

diff --git a/ld/emultempl/loongarchelf.em b/ld/emultempl/loongarchelf.em
new file mode 100644
index 00000000000..b688ef7bc1d
--- /dev/null
+++ b/ld/emultempl/loongarchelf.em
@@ -0,0 +1,87 @@
+# This shell script emits a C file. -*- C -*-
+#   Copyright (C) 2021 Free Software Foundation, Inc.
+#   Contributed by Loongson Ltd.
+#
+# This file is part of the GNU Binutils.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; see the file COPYING3. If not,
+# see <http://www.gnu.org/licenses/>.
+
+fragment <<EOF
+
+#include "ldmain.h"
+#include "ldctor.h"
+#include "elf/loongarch.h"
+
+static void
+larch_elf_before_allocation (void)
+{
+  gld${EMULATION_NAME}_before_allocation ();
+
+  if (link_info.discard == discard_sec_merge)
+    link_info.discard = discard_l;
+
+  if (!bfd_link_relocatable (&link_info))
+    {
+      /* We always need at least some relaxation to handle code alignment.  */
+      if (RELAXATION_DISABLED_BY_USER)
+	TARGET_ENABLE_RELAXATION;
+      else
+	ENABLE_RELAXATION;
+    }
+
+  link_info.relax_pass = 3;
+}
+
+static void
+gld${EMULATION_NAME}_after_allocation (void)
+{
+  int need_layout = 0;
+
+  /* Don't attempt to discard unused .eh_frame sections until the final link,
+     as we can't reliably tell if they're used until after relaxation.  */
+  if (!bfd_link_relocatable (&link_info))
+    {
+      need_layout = bfd_elf_discard_info (link_info.output_bfd, &link_info);
+      if (need_layout < 0)
+	{
+	  einfo (_("%X%P: .eh_frame/.stab edit: %E\n"));
+	  return;
+	}
+    }
+
+  /* gld${EMULATION_NAME}_map_segments (need_layout); */
+  ldelf_map_segments (need_layout);
+}
+
+/* This is a convenient point to tell BFD about target specific flags.
+   After the output has been created, but before inputs are read.  */
+
+static void
+larch_create_output_section_statements (void)
+{
+  /* See PR 22920 for an example of why this is necessary.  */
+  if (strstr (bfd_get_target (link_info.output_bfd), "loong") == NULL)
+    {
+      einfo (_("%F%P: error: cannot change output format"
+	       " whilst linking %s binaries\n"), "LoongArch");
+      return;
+    }
+}
+
+EOF
+
+LDEMUL_BEFORE_ALLOCATION=larch_elf_before_allocation
+LDEMUL_AFTER_ALLOCATION=gld${EMULATION_NAME}_after_allocation
+LDEMUL_CREATE_OUTPUT_SECTION_STATEMENTS=larch_create_output_section_statements