diff options
Diffstat (limited to 'aclocal.m4')
| -rw-r--r-- | aclocal.m4 | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/aclocal.m4 b/aclocal.m4 index 042a7e3c38..64351d0a00 100644 --- a/aclocal.m4 +++ b/aclocal.m4 @@ -248,3 +248,36 @@ dnl LIBC_CONFIG_VAR(make-variable, shell-value) AC_DEFUN([LIBC_CONFIG_VAR], [config_vars="$config_vars $1 = $2"]) + +dnl Check that function FUNC was inlined as a builtin. The code fragment +dnl CODE is compiled with additional options CC_OPTION. If FUNC is +dnl not found in the assembly then it is assumed the compiler has support +dnl for this builtin and has inlined the call. If the compiler has the +dnl feature then ACTION-IF-TRUE is called, otherwise ACTION-IF-FALSE. +dnl It is up to the caller to provide a CC_OPTION that ensures the +dnl builtin is inlined if present. +dnl Warning: This may not work for some machines. For example on ARM the +dnl ABI dictates that some functions should not be inlined and instead +dnl should be provided by a compiler helper library e.g. __aeabi_memcpy. +dnl This is done to reduce code size. +dnl LIBC_COMPILER_BUILTIN([func], [code], [cc_option], [action-if-true], [action-if-false]) +AC_DEFUN([LIBC_COMPILER_BUILTIN_INLINED], +[AC_MSG_CHECKING([for compiler support of inlined builtin function $1]) +libc_compiler_builtin_inlined=no +cat > conftest.c <<EOF +int _start (void) { $2 return 0; } +EOF +if ! AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS + $3 -nostdlib -nostartfiles + -S conftest.c -o - | fgrep "$1" + 1>&AS_MESSAGE_LOG_FD]) +then + libc_compiler_builtin_inlined=yes +fi +rm -f conftest* +if test $libc_compiler_builtin_inlined = yes; then + $4 +else + $5 +fi +AC_MSG_RESULT($libc_compiler_builtin_inlined)]) |