add support for riscv-none-embed-*

config.sub

@@ -450,6 +450,9 @@ case $basic_machine in
 	| ymp-* \
 	| z8k-* | z80-*)
 		;;
+	# [GNU MCU Eclipse]
+ 	riscv-*)
+ 		;;
 	# Recognize the basic CPU types without company name, with glob match.
 	xtensa*)
 		basic_machine=$basic_machine-unknown
@@ -1419,6 +1422,9 @@ case $os in
 	      | -onefs* | -tirtos* | -phoenix* | -fuchsia* | -redox* | -bme*)
 	# Remember, each alternative MUST END IN *, to match a version number.
 		;;
+	# [GNU MCU Eclipse]
+	-embed)
+		;;
 	-qnx*)
 		case $basic_machine in
 		    x86-* | i*86-*)

gcc/config.gcc

@@ -2071,8 +2071,17 @@ riscv*-*-linux*)
 	# automatically detect that GAS supports it, yet we require it.
 	gcc_cv_initfini_array=yes
 	;;
-riscv*-*-elf* | riscv*-*-rtems*)
-	tm_file="elfos.h newlib-stdint.h ${tm_file} riscv/elf.h"
+# [GNU MCU Eclipse]
+riscv*-*-elf* | riscv*-*-rtems* | riscv-none-embed)
+	# [GNU MCU Eclipse]
+	case ${target} in
+	riscv-none-embed)
+	  tm_file="elfos.h newlib-stdint.h ${tm_file} riscv/elf-embed.h"
+	  ;;
+	*)
+	  tm_file="elfos.h newlib-stdint.h ${tm_file} riscv/elf.h"
+	  ;;
+	esac
 	case ${target} in
 	*-*-rtems*)
 	  tm_file="${tm_file} rtems.h riscv/rtems.h"

gcc/config/riscv/elf-embed.h

@@ -0,0 +1,39 @@
+/* Target macros for riscv*-elf targets.
+   Copyright (C) 1994-2017 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 LINK_SPEC "\
+-melf" XLEN_SPEC "lriscv \
+%{mno-relax:--no-relax} \
+%{shared}"
+
+/* Link against Newlib libraries, because the ELF backend assumes Newlib.
+   Handle the circular dependence between libc and libgloss. */
+#undef  LIB_SPEC
+// GNU MCU Eclipse
+// #define LIB_SPEC "--start-group -lc %{!specs=nosys.specs:-lgloss} --end-group"
+// The sequence is copied from arm-none-eabi, might not be exactly right.
+#define LIB_SPEC "--start-group -lgcc -lg -lc --end-group"
+
+#undef  STARTFILE_SPEC
+#define STARTFILE_SPEC "crt0%O%s crtbegin%O%s"
+
+#undef  ENDFILE_SPEC
+#define ENDFILE_SPEC "crtend%O%s"
+
+#define NO_IMPLICIT_EXTERN_C 1