[gcc r14-3668] LoongArch: support loongarch*-elf target

[LuluCheng <chenglulu@gcc.gnu.org>]

https://gcc.gnu.org/g:976f4f9e4770a567550e8b9a9f2fc531206cebba

commit r14-3668-g976f4f9e4770a567550e8b9a9f2fc531206cebba
Author: Yang Yujie <yangyujie@loongson.cn>
Date:   Fri Jun 30 17:07:59 2023 +0800

    LoongArch: support loongarch*-elf target
    
    gcc/ChangeLog:
    
            * config.gcc: add loongarch*-elf target.
            * config/loongarch/elf.h: New file.
            Link against newlib by default.
    
    libgcc/ChangeLog:
    
            * config.host: add loongarch*-elf target.

Diff:
---
 gcc/config.gcc             | 15 +++++++++++++-
 gcc/config/loongarch/elf.h | 51 ++++++++++++++++++++++++++++++++++++++++++++++
 libgcc/config.host         |  9 ++++++--
 3 files changed, 72 insertions(+), 3 deletions(-)

diff --git a/gcc/config.gcc b/gcc/config.gcc
index 89af167e5d94..b8aea73a9e0b 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -2491,6 +2491,18 @@ loongarch*-*-linux*)
 	gcc_cv_initfini_array=yes
 	;;
 
+loongarch*-*-elf*)
+	tm_file="elfos.h newlib-stdint.h ${tm_file}"
+	tm_file="${tm_file} loongarch/elf.h loongarch/linux.h"
+	tmake_file="${tmake_file} loongarch/t-linux"
+	gnu_ld=yes
+	gas=yes
+
+	# For .init_array support.  The configure script cannot always
+	# automatically detect that GAS supports it, yet we require it.
+	gcc_cv_initfini_array=yes
+	;;
+
 mips*-*-netbsd*)			# NetBSD/mips, either endian.
 	target_cpu_default="MASK_ABICALLS"
 	tm_file="elfos.h ${tm_file} mips/elf.h ${nbsd_tm_file} mips/netbsd.h"
@@ -4932,8 +4944,9 @@ case "${target}" in
 		esac
 
 		case ${target} in
-		  *-linux-gnu*)  triplet_os="linux-gnu";;
+		  *-linux-gnu*) triplet_os="linux-gnu";;
 		  *-linux-musl*) triplet_os="linux-musl";;
+		  *-elf*) triplet_os="elf";;
 		  *)
 			  echo "Unsupported target ${target}." 1>&2
 			  exit 1
diff --git a/gcc/config/loongarch/elf.h b/gcc/config/loongarch/elf.h
new file mode 100644
index 000000000000..523d5c756b4e
--- /dev/null
+++ b/gcc/config/loongarch/elf.h
@@ -0,0 +1,51 @@
+/* Definitions for LoongArch ELF-based systems.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC 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, or (at your option)
+any later version.
+
+GCC 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 GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+/* Define the size of the wide character type.  */
+#undef WCHAR_TYPE
+#define WCHAR_TYPE "int"
+
+#undef WCHAR_TYPE_SIZE
+#define WCHAR_TYPE_SIZE 32
+
+
+/* GNU-specific SPEC definitions.  */
+#define GNU_USER_LINK_EMULATION "elf" ABI_GRLEN_SPEC "loongarch"
+
+#undef GNU_USER_TARGET_LINK_SPEC
+#define GNU_USER_TARGET_LINK_SPEC \
+  "%{shared} -m " GNU_USER_LINK_EMULATION
+
+
+/* Link against Newlib libraries, because the ELF backend assumes Newlib.
+   Handle the circular dependence between libc and libgloss.  */
+#undef  LIB_SPEC
+#define LIB_SPEC "--start-group -lc %{!specs=nosys.specs:-lgloss} --end-group"
+
+#undef LINK_SPEC
+#define LINK_SPEC GNU_USER_TARGET_LINK_SPEC
+
+#undef  STARTFILE_SPEC
+#define STARTFILE_SPEC "crt0%O%s crtbegin%O%s"
+
+#undef  ENDFILE_SPEC
+#define ENDFILE_SPEC "crtend%O%s"
+
+#undef SUBTARGET_CC1_SPEC
+#define SUBTARGET_CC1_SPEC "%{profile:-p}"
diff --git a/libgcc/config.host b/libgcc/config.host
index c94d69d84b7c..6a112a07b140 100644
--- a/libgcc/config.host
+++ b/libgcc/config.host
@@ -136,7 +136,7 @@ hppa*-*-*)
 lm32*-*-*)
 	cpu_type=lm32
 	;;
-loongarch*-*-*)
+loongarch*-*)
 	cpu_type=loongarch
 	tmake_file="loongarch/t-loongarch"
 	if test "${libgcc_cv_loongarch_hard_float}" = yes; then
@@ -944,7 +944,7 @@ lm32-*-uclinux*)
         extra_parts="$extra_parts crtbegin.o crtendS.o crtbeginT.o"
         tmake_file="lm32/t-lm32 lm32/t-uclinux t-libgcc-pic t-softfp-sfdf t-softfp"
 	;;
-loongarch*-*-linux*)
+loongarch*-linux*)
 	extra_parts="$extra_parts crtfastmath.o"
 	tmake_file="${tmake_file} t-crtfm loongarch/t-crtstuff"
 	case ${host} in
@@ -954,6 +954,11 @@ loongarch*-*-linux*)
 	esac
 	md_unwind_header=loongarch/linux-unwind.h
 	;;
+loongarch*-elf*)
+	extra_parts="$extra_parts crtfastmath.o"
+	tmake_file="${tmake_file} t-crtfm loongarch/t-crtstuff"
+	tmake_file="${tmake_file} t-slibgcc-libgcc"
+	;;
 m32r-*-elf*)
 	tmake_file="$tmake_file m32r/t-m32r t-fdpbit"
 	extra_parts="$extra_parts crtinit.o crtfini.o"