[gcc(refs/vendors/riscv/heads/gcc-15-with-riscv-opts)] [PATCH] riscv: Add support for riscv*-gnu (GNU/Hurd on RISC-V)

[Jeff Law]

https://gcc.gnu.org/g:c39ee1a532e41c6eb9a8829e3301ed71939cf7dd

commit c39ee1a532e41c6eb9a8829e3301ed71939cf7dd
Author: Hakan Candar <hakancandar@protonmail.com>
Date:   Fri Apr 18 07:08:44 2025 -0600

    [PATCH] riscv: Add support for riscv*-gnu (GNU/Hurd on RISC-V)
    
    This produces a toolchain that can successfully build binaries targeting
    riscv*-gnu.
    
    gcc/ChangeLog:
            * config.gcc: Recognize riscv*-*-gnu* targets.
            * config/riscv/gnu.h: New file.
    
    (cherry picked from commit 869f2ab30ad53033ad6ac82569d74ce3a99fe510)

Diff:
---
 gcc/config.gcc         | 14 ++++++++++++
 gcc/config/riscv/gnu.h | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+)

diff --git a/gcc/config.gcc b/gcc/config.gcc
index 53be4a7cfe75..82e23d2c997b 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -2540,6 +2540,20 @@ riscv*-*-linux*)
 	gcc_cv_initfini_array=yes
 	with_tls=${with_tls:-trad}
 	;;
+riscv*-*-gnu*)
+	tm_file="elfos.h gnu-user.h gnu.h glibc-stdint.h ${tm_file} riscv/gnu.h"
+	tmake_file="${tmake_file} riscv/t-riscv"
+	gnu_ld=yes
+	gas=yes
+	case $target in
+	riscv32be-*|riscv64be-*)
+		tm_defines="${tm_defines} TARGET_BIG_ENDIAN_DEFAULT=1"
+		;;
+	esac
+	# Force .init_array support.  The configure script cannot always
+	# 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"
 	case ${target} in
diff --git a/gcc/config/riscv/gnu.h b/gcc/config/riscv/gnu.h
new file mode 100644
index 000000000000..047399b10ff4
--- /dev/null
+++ b/gcc/config/riscv/gnu.h
@@ -0,0 +1,59 @@
+/* Definitions for RISC-V GNU/Hurd systems with ELF format.
+   Copyright (C) 1998-2025 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 TARGET_OS_CPP_BUILTINS()				\
+  do {								\
+    GNU_USER_TARGET_OS_CPP_BUILTINS();				\
+  } while (0)
+
+#define GNU_USER_DYNAMIC_LINKER "/lib/ld-riscv" XLEN_SPEC "-" ABI_SPEC ".so.1"
+
+#define ICACHE_FLUSH_FUNC "__riscv_flush_icache"
+
+#define CPP_SPEC "%{pthread:-D_REENTRANT}"
+
+#define LD_EMUL_SUFFIX \
+  "%{mabi=lp64d:}" \
+  "%{mabi=lp64f:_lp64f}" \
+  "%{mabi=lp64:_lp64}" \
+  "%{mabi=ilp32d:}" \
+  "%{mabi=ilp32f:_ilp32f}" \
+  "%{mabi=ilp32:_ilp32}"
+
+#define LINK_SPEC "\
+-melf" XLEN_SPEC DEFAULT_ENDIAN_SPEC "riscv" LD_EMUL_SUFFIX " \
+%{mno-relax:--no-relax} \
+-X \
+%{mbig-endian:-EB} \
+%{mlittle-endian:-EL} \
+%{shared} \
+  %{!shared: \
+    %{!static: \
+      %{!static-pie: \
+	%{rdynamic:-export-dynamic} \
+	-dynamic-linker " GNU_USER_DYNAMIC_LINKER "}} \
+    %{static:-static} %{static-pie:-static -pie --no-dynamic-linker -z text}}"
+
+#define STARTFILE_PREFIX_SPEC 			\
+   "/lib" XLEN_SPEC "/" ABI_SPEC "/ "		\
+   "/usr/lib" XLEN_SPEC "/" ABI_SPEC "/ "	\
+   "/lib/ "					\
+   "/usr/lib/ "
+
+#define RISCV_USE_CUSTOMISED_MULTI_LIB select_by_abi