diff mbox series

RISC-V: Add --with-cmodel configure option

Message ID 20240802041658.3629522-1-hau.hsu@sifive.com
State Superseded
Headers
Series RISC-V: Add --with-cmodel configure option |

Checks

Context Check Description
rivoscibot/toolchain-ci-rivos-lint warning Lint failed
rivoscibot/toolchain-ci-rivos-apply-patch success Patch applied
rivoscibot/toolchain-ci-rivos-build--newlib-rv64gcv-lp64d-multilib success Build passed
rivoscibot/toolchain-ci-rivos-build--linux-rv64gc_zba_zbb_zbc_zbs-lp64d-multilib success Build passed
rivoscibot/toolchain-ci-rivos-build--linux-rv64gcv-lp64d-multilib success Build passed
rivoscibot/toolchain-ci-rivos-build--newlib-rv64gc-lp64d-non-multilib success Build passed
rivoscibot/toolchain-ci-rivos-build--linux-rv64gc-lp64d-non-multilib success Build passed
rivoscibot/toolchain-ci-rivos-test success Testing passed
linaro-tcwg-bot/tcwg_gcc_build--master-arm fail Build failed
linaro-tcwg-bot/tcwg_gcc_build--master-aarch64 fail Build failed

Commit Message

Hau Hsu Aug. 2, 2024, 4:16 a.m. UTC 
  Sometimes we want to use default cmodel other than medlow. Add a GCC
configure option for that.

gcc/ChangeLog:

    * config.gcc (riscv*-*-*): Add support for --with-cmodel configure option.
    * config/riscv/riscv.h (TARGET_RISCV_DEFAULT_CMODEL): Define default cmodel.
    * configure: Regenerate.
    * configure.ac: Add --with-cmodel configure option.
    * doc/install.texi: Document --with-cmodel configure option.
    * doc/invoke.texi (-mcmodel): Mention --with-cmodel configure option.
---
 gcc/config.gcc           | 19 +++++++++++++++++--
 gcc/config/riscv/riscv.h |  2 ++
 gcc/configure            | 15 +++++++++++++--
 gcc/configure.ac         |  5 +++++
 gcc/doc/install.texi     |  4 ++++
 gcc/doc/invoke.texi      |  6 ++++--
 6 files changed, 45 insertions(+), 6 deletions(-)

Comments

Kito Cheng Aug. 2, 2024, 4:32 a.m. UTC | #1 
compact code mode is our downstream stuffs, so...it should drop it from the
patch

Hau Hsu <hau.hsu@sifive.com> 於 2024年8月2日 週五 12:17 寫道：

> Sometimes we want to use default cmodel other than medlow. Add a GCC
> configure option for that.
>
> gcc/ChangeLog:
>
>     * config.gcc (riscv*-*-*): Add support for --with-cmodel configure
> option.
>     * config/riscv/riscv.h (TARGET_RISCV_DEFAULT_CMODEL): Define default
> cmodel.
>     * configure: Regenerate.
>     * configure.ac: Add --with-cmodel configure option.
>     * doc/install.texi: Document --with-cmodel configure option.
>     * doc/invoke.texi (-mcmodel): Mention --with-cmodel configure option.
> ---
>  gcc/config.gcc           | 19 +++++++++++++++++--
>  gcc/config/riscv/riscv.h |  2 ++
>  gcc/configure            | 15 +++++++++++++--
>  gcc/configure.ac         |  5 +++++
>  gcc/doc/install.texi     |  4 ++++
>  gcc/doc/invoke.texi      |  6 ++++--
>  6 files changed, 45 insertions(+), 6 deletions(-)
>
> diff --git a/gcc/config.gcc b/gcc/config.gcc
> index a36dd1bcbc6..a4537d4b940 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 "${with_cmodel}" in
> +                       medlow | medany | compact)
> +                               ;;
> +                       *)
> +                               echo "invalid option for --with-cmodel:
> '${with_cmodel}', available values are 'medlow' 'medany' 'compact'" 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
> --
> 2.39.3
>
>
Hau Hsu Aug. 2, 2024, 5:12 a.m. UTC | #2 
Oh sorry. Sent v2 and replaced compact code model with large code model.


Hau Hsu






> On Aug 2, 2024, at 12:32 PM, Kito Cheng <kito.cheng@gmail.com> wrote:
> 
> compact code mode is our downstream stuffs, so...it should drop it from the patch
> 
> 
> Hau Hsu <hau.hsu@sifive.com <mailto:hau.hsu@sifive.com>> 於 2024年8月2日 週五 12:17 寫道：
>> Sometimes we want to use default cmodel other than medlow. Add a GCC
>> configure option for that.
>> 
>> gcc/ChangeLog:
>> 
>>     * config.gcc (riscv*-*-*): Add support for --with-cmodel configure option.
>>     * config/riscv/riscv.h (TARGET_RISCV_DEFAULT_CMODEL): Define default cmodel.
>>     * configure: Regenerate.
>>     * configure.ac <http://configure.ac/>: Add --with-cmodel configure option.
>>     * doc/install.texi: Document --with-cmodel configure option.
>>     * doc/invoke.texi (-mcmodel): Mention --with-cmodel configure option.
>> ---
>>  gcc/config.gcc           | 19 +++++++++++++++++--
>>  gcc/config/riscv/riscv.h |  2 ++
>>  gcc/configure            | 15 +++++++++++++--
>>  gcc/configure.ac <http://configure.ac/>         |  5 +++++
>>  gcc/doc/install.texi     |  4 ++++
>>  gcc/doc/invoke.texi      |  6 ++++--
>>  6 files changed, 45 insertions(+), 6 deletions(-)
>> 
>> diff --git a/gcc/config.gcc b/gcc/config.gcc
>> index a36dd1bcbc6..a4537d4b940 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 "${with_cmodel}" in
>> +                       medlow | medany | compact)
>> +                               ;;
>> +                       *)
>> +                               echo "invalid option for --with-cmodel: '${with_cmodel}', available values are 'medlow' 'medany' 'compact'" 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 <http://configure.ac/> b/gcc/configure.ac <http://configure.ac/>
>> index eaa01d0d7e5..1339bb2ba3b 100644
>> --- a/gcc/configure.ac <http://configure.ac/>
>> +++ b/gcc/configure.ac <http://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
>> -- 
>> 2.39.3
>>
diff mbox series

Patch

diff --git a/gcc/config.gcc b/gcc/config.gcc
index a36dd1bcbc6..a4537d4b940 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 | compact)
+				;;
+			*)
+				echo "invalid option for --with-cmodel: '${with_cmodel}', available values are 'medlow' 'medany' 'compact'" 1>&2
+				exit 1
+				;;
+			esac
+			tm_defines="${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