The default C library is normally computed based on the target
triplet. However, for embedded systems, it can be useful to leave the
triplet alone while changing which C library is used by default. Other
C libraries may still be available on the system so the compiler and
can be used by specifying suitable include and library paths at build
time.
If an unknown --with-default-libc= value is provided, emit an error
and stop.
Signed-off-by: Keith Packard <kei...@keithp.com>
---
gcc/config.gcc | 63 +++++++++++++++++++++++++++++++++++++++---------
gcc/configure.ac | 4 +++
2 files changed, 56 insertions(+), 11 deletions(-)
diff --git a/gcc/config.gcc b/gcc/config.gcc
index f57897b0298..76fca94c409 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -697,6 +697,8 @@ esac
# Common C libraries.
tm_defines="$tm_defines LIBC_GLIBC=1 LIBC_UCLIBC=2 LIBC_BIONIC=3 LIBC_MUSL=4
LIBC_PICOLIBC=5"
+default_libc=""
+
# 32-bit x86 processors supported by --with-arch=. Each processor
# MUST be separated by exactly one space.
x86_archs="athlon athlon-4 athlon-fx athlon-mp athlon-tbird \
@@ -913,16 +915,16 @@ case ${target} in
esac
case $target in
*-*-*android*)
- tm_defines="$tm_defines DEFAULT_LIBC=LIBC_BIONIC"
+ default_libc=LIBC_BIONIC
;;
*-*-*uclibc* | *-*-uclinuxfdpiceabi)
- tm_defines="$tm_defines DEFAULT_LIBC=LIBC_UCLIBC"
+ default_libc=LIBC_UCLIBC
;;
*-*-*musl*)
- tm_defines="$tm_defines DEFAULT_LIBC=LIBC_MUSL"
+ default_libc=LIBC_MUSL
;;
*)
- tm_defines="$tm_defines DEFAULT_LIBC=LIBC_GLIBC"
+ default_libc=LIBC_GLIBC
;;
esac
# Assume that glibc or uClibc or Bionic are being used and so __cxa_atexit
@@ -1037,7 +1039,8 @@ case ${target} in
case ${enable_threads} in
"" | yes | posix) thread_file='posix' ;;
esac
- tm_defines="$tm_defines DEFAULT_LIBC=LIBC_UCLIBC SINGLE_LIBC"
+ tm_defines="$tm_defines SINGLE_LIBC"
+ default_libc=LIBC_UCLIBC
;;
*-*-rdos*)
use_gcc_stdint=wrap
@@ -1164,7 +1167,7 @@ case ${target} in
esac
;;
*-picolibc-*)
- tm_defines="$tm_defines DEFAULT_LIBC=LIBC_PICOLIBC"
+ default_libc=LIBC_PICOLIBC
;;
*-*-elf|arc*-*-elf*)
@@ -1752,13 +1755,13 @@ csky-*-*)
case ${target} in
csky-*-linux-gnu*)
- tm_defines="$tm_defines DEFAULT_LIBC=LIBC_GLIBC"
+ default_libc=LIBC_GLIBC
# Force .init_array support. The configure script
cannot always
# automatically detect that GAS supports it, yet we
require it.
gcc_cv_initfini_array=yes
;;
csky-*-linux-uclibc*)
- tm_defines="$tm_defines DEFAULT_LIBC=LIBC_UCLIBC"
+ default_libc=LIBC_UCLIBC
default_use_cxa_atexit=no
;;
*)
@@ -3149,7 +3152,7 @@ powerpc*-wrs-vxworks7r*)
tmake_file="${tmake_file} t-linux rs6000/t-linux64 rs6000/t-fprules
rs6000/t-ppccomm"
tmake_file="${tmake_file} rs6000/t-vxworks"
- tm_defines="$tm_defines DEFAULT_LIBC=LIBC_GLIBC"
+ default_libc=LIBC_GLIBC
extra_objs="$extra_objs linux.o rs6000-linux.o"
;;
powerpc-wrs-vxworks*)
@@ -6168,10 +6171,48 @@ i[34567]86-*-* | x86_64-*-*)
esac
+case "${with_default_libc}" in
+glibc)
+ default_libc=LIBC_GLIBC
+ ;;
+uclibc)
+ default_libc=LIBC_UCLIBC
+ ;;
+bionic)
+ default_libc=LIBC_BIONIC
+ ;;
+musl)
+ default_libc=LIBC_MUSL
+ ;;
+newlib)
+ # Newlib configurations don't set the DEFAULT_LIBC variable, so
+ # avoid changing those by allowing --with-default-libc=newlib but
+ # not actually setting the DEFAULT_LIBC variable.
+ default_libc=
+ ;;
+picolibc)
+ default_libc=LIBC_PICOLIBC
+ ;;
+"")
+ ;;
+*)
+ echo "Unknown libc in --with-default-libc=$with_default_libc" 1>&2
+ exit 1
+ ;;
+esac
+
+case "$default_libc" in
+"")
+ ;;
+*)
+ tm_defines="$tm_defines DEFAULT_LIBC=$default_libc"
+ ;;
+esac
+
# Targets for picolibc should include picolibc-spec.h to allow
# use of picolibc-specific compiler flags
-case ${target} in
-*picolibc*)
+case "$default_libc" in
+LIBC_PICOLIBC)
# __cxa_atexit is provided.
default_use_cxa_atexit=yes
use_gcc_stdint=wrap
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 5a178e056ef..b8ae10d66fc 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -2559,6 +2559,10 @@ if { { test x$host != x$target && test "x$with_sysroot"
= x ; } ||
fi
AC_SUBST(inhibit_libc)
+AC_ARG_WITH(default-libc,
+ [AS_HELP_STRING([--with-default-libc],
+ [Use specified default C library])])
+
# When building gcc with a cross-compiler, we need to adjust things so
# that the generator programs are still built with the native compiler.
# Also, we cannot run fixincludes.
--
2.45.2
