[v2] RISC-V: Add --with-cmodel configure option

diff --git a/gcc/config.gcc b/gcc/config.gcc
index a36dd1bcbc6..a5ca9d172ca 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -4723,7 +4723,7 @@  case "${target}" in
 		;;
 
 	riscv*-*-*)
-		supported_defaults="abi arch tune riscv_attribute isa_spec tls"
+		supported_defaults="abi arch tune riscv_attribute isa_spec tls cmodel"
 
 		case "${target}" in
 		riscv-* | riscv32*) xlen=32 ;;
@@ -4879,6 +4879,21 @@  case "${target}" in
 				exit 1
 			esac
 		fi
+
+		# Handle --with-cmodel.
+		if test "x${with_cmodel}" != xdefault; then
+			# Make sure --with-cmodel is valid.  If it was not specified,
+			# use medlow as the default value.
+			case "${with_cmodel}" in
+			medlow | medany | large)
+				;;
+			*)
+				echo "invalid option for --with-cmodel: '${with_cmodel}', available values are 'medlow' 'medany' 'large'" 1>&2
+				exit 1
+				;;
+			esac
+			tm_defines="${tm_defines} TARGET_RISCV_DEFAULT_CMODEL=${with_cmodel}"
+		fi
 		;;
 
 	mips*-*-*)
@@ -6071,7 +6086,7 @@  case ${target} in
 esac
 
 t=
-all_defaults="abi cpu cpu_32 cpu_64 arch arch_32 arch_64 tune tune_32 tune_64 schedule float mode fpu nan fp_32 odd_spreg_32 divide llsc mips-plt synci tls lxc1-sxc1 madd4 isa_spec compact-branches msa"
+all_defaults="abi cpu cpu_32 cpu_64 arch arch_32 arch_64 tune tune_32 tune_64 schedule float mode fpu nan fp_32 odd_spreg_32 divide llsc mips-plt synci tls lxc1-sxc1 madd4 isa_spec compact-branches msa cmodel"
 for option in $all_defaults
 do
 	eval "val=\$with_"`echo $option | sed s/-/_/g`
diff --git a/gcc/config/riscv/riscv.h b/gcc/config/riscv/riscv.h
index 6f040011864..68173ebccb4 100644
--- a/gcc/config/riscv/riscv.h
+++ b/gcc/config/riscv/riscv.h
@@ -65,6 +65,7 @@  extern const char *riscv_arch_help (int argc, const char **argv);
    --with-tune is ignored if -mtune or -mcpu is specified.
    --with-isa-spec is ignored if -misa-spec is specified.
    --with-tls is ignored if -mtls-dialect is specified.
+   --with-cmodel is ignored if -mcmodel is specified.
 
    But using default -march/-mtune value if -mcpu don't have valid option.  */
 #define OPTION_DEFAULT_SPECS \
@@ -77,6 +78,7 @@  extern const char *riscv_arch_help (int argc, const char **argv);
   {"abi", "%{!mabi=*:-mabi=%(VALUE)}" },				\
   {"isa_spec", "%{!misa-spec=*:-misa-spec=%(VALUE)}" },			\
   {"tls", "%{!mtls-dialect=*:-mtls-dialect=%(VALUE)}"},         	\
+  {"cmodel", "%{!mcmodel=*:-mcmodel=%(VALUE)}" }, \
 
 #ifdef IN_LIBGCC2
 #undef TARGET_64BIT
diff --git a/gcc/configure b/gcc/configure
index 557ea5fa3ac..826caf8dc2c 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -1000,6 +1000,7 @@  with_changes_root_url
 enable_languages
 with_multilib_list
 with_multilib_generator
+with_cmodel
 with_zstd
 with_zstd_include
 with_zstd_lib
@@ -1880,6 +1881,7 @@  Optional Packages:
                           SH and x86-64 only)
   --with-multilib-generator
                           Multi-libs configuration string (RISC-V only)
+  --with-cmodel           Code model configuration string (RISC-V only)
   --with-zstd=PATH        specify prefix directory for installed zstd library.
                           Equivalent to --with-zstd-include=PATH/include plus
                           --with-zstd-lib=PATH/lib
@@ -8381,6 +8383,15 @@  else
 fi
 
 
+
+# Check whether --with-cmodel was given.
+if test "${with_cmodel+set}" = set; then :
+  withval=$with_cmodel; :
+else
+  with_cmodel=medlow
+fi
+
+
 # -------------------------
 # Checks for other programs
 # -------------------------
@@ -21406,7 +21417,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 21409 "configure"
+#line 21420 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -21512,7 +21523,7 @@  else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 21515 "configure"
+#line 21526 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/gcc/configure.ac b/gcc/configure.ac
index eaa01d0d7e5..1339bb2ba3b 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -1212,6 +1212,11 @@  AC_ARG_WITH(multilib-generator,
 :,
 with_multilib_generator=default)
 
+AC_ARG_WITH(cmodel,
+[AS_HELP_STRING([--with-cmodel], [Code model configuration string (RISC-V only)])],
+:,
+with_cmodel=medlow)
+
 # -------------------------
 # Checks for other programs
 # -------------------------
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index 4973f195daf..53f8dd21e37 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -1519,6 +1519,10 @@  Use big endian by default.  Provide a multilib for little endian.
 Use little endian by default.  Provide a multilib for big endian.
 @end table
 
+@item --with-cmodel=@var{cmodel}
+Specify what code model to use by default.
+Currently only implemented for riscv*-*-*.
+
 @item --enable-threads
 Specify that the target
 supports threads.  This affects the Objective-C compiler and runtime
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 54ecd9a00eb..f219cd3db19 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -31285,8 +31285,10 @@  element-misaligned vector memory access.
 @item -mcmodel=medlow
 Generate code for the medium-low code model. The program and its statically
 defined symbols must lie within a single 2 GiB address range and must lie
-between absolute addresses @minus{}2 GiB and +2 GiB. Programs can be
-statically or dynamically linked. This is the default code model.
+between absolute addresses @minus{}2 GiB and +2 GiB. Programs can be statically
+or dynamically linked. This is the default code model unless GCC has been
+configured with @option{--with-cmodel=} specifying a different default code
+model.
 
 @opindex mcmodel=medany
 @item -mcmodel=medany