build: switch to ordinary auto* tools system.

[cln.git] / m4 / cc.m4

diff --git a/m4/cc.m4 b/m4/cc.m4
index 0f071e57d08ca457feb780209c522fa1d7af309c..425e799172f336566467b0a3f05e739a9ced06bf 100644 (file)
--- a/m4/cc.m4
+++ b/m4/cc.m4
@@ -1,31 +1,50 @@
-dnl The CLN manual says that without CFLAGS or CXXFLAGS being set compilation
-dnl will happen with -O.  However, AC_PROG_CC and AC_PROG_CXX set CFLAGS and
-dnl CXXFLAGS to "-g -O2", which produces way too large binaries.
+dnl Checks whether the stack can be marked nonexecutable by passing an option
+dnl to the C-compiler when acting on .s files. Appends that option to ASFLAGS.
+dnl This macro is adapted from one found in GLIBC-2.3.5.
+AC_DEFUN([CL_AS_NOEXECSTACK],[
+AC_REQUIRE([AC_PROG_CC])
+AC_REQUIRE([AM_PROG_AS])
+AC_CACHE_CHECK([whether --noexecstack is desirable for .s files], cl_cv_as_noexecstack, [dnl
+  cat > conftest.c <<EOF
+void foo() {}
+EOF
+  if AC_TRY_COMMAND([${CCAS} $CFLAGS $CPPFLAGS
+                     -S -o conftest.s conftest.c >/dev/null]) \
+     && grep -q .note.GNU-stack conftest.s \
+     && AC_TRY_COMMAND([${CCAS} $CFLAGS $CPPFLAGS -Wa,--noexecstack
+                       -c -o conftest.o conftest.s >/dev/null])
+  then
+    cl_cv_as_noexecstack=yes
+  else
+    cl_cv_as_noexecstack=no
+  fi
+  rm -f conftest*])
+  if test "$cl_cv_as_noexecstack" = yes; then
+    CCASFLAGS="$CCASFLAGS -Wa,--noexecstack"
+  fi
+])
 
 
-dnl Wrapper around AC_PROG_CC setting CFLAGS to plain "-O" as opposed to
-dnl "-g -O2" for the GNU compiler (unless CFLAGS was set before).
-AC_DEFUN([CL_PROG_CC],
-[cl_test_CFLAGS=${CFLAGS+set}
-# Make sure this macro does not come after AC_PROG_CC.
-# Otherwise CFLAGS would already be set.
-AC_BEFORE([$0],[AC_PROG_CC])dnl
-AC_PROG_CC([$1])
-if test "$cl_test_CFLAGS" != set && test "$ac_compiler_gnu" = yes; then
-    CFLAGS="-O"
+dnl Checks whether the compiler supports __attribute__((flatten)).
+AC_DEFUN([CL_ATTRIBUTE_FLATTEN],[
+AC_REQUIRE([AC_PROG_CXX])
+AC_CACHE_CHECK([whether the compiler supports __attribute__((flatten))], cl_cv_have_attr_flatten, [dnl
+  cat > conftest.cc <<EOF
+void f() __attribute__((flatten));
+EOF
+if AC_TRY_COMMAND(${CXX-g++} $CXXFLAGS -c conftest.cc >/dev/null 2>conftest.stderr)
+then
+  if grep -i "warning" conftest.stderr > /dev/null; then
+    cl_cv_have_attr_flatten=no
+  else
+    cl_cv_have_attr_flatten=yes
+  fi
+else
+  cl_cv_have_attr_flatten=no
 fi
+rm -f conftest*
 ])
-
-
-dnl Wrapper around AC_PROG_CXX setting CXXFLAGS to plain "-O" as opposed to
-dnl "-g -O2" for the GNU compiler (unless CXXFLAGS was set before).
-AC_DEFUN([CL_PROG_CXX],
-[cl_test_CXXFLAGS=${CXXFLAGS+set}
-# Make sure this macro does not come after AC_PROG_CXX.
-# Otherwise CXXFLAGS would already be set.
-AC_BEFORE([$0],[AC_PROG_CXX])dnl
-AC_PROG_CXX([$1])
-if test "$cl_test_CXXFLAGS" != set && test "$ac_compiler_gnu" = yes; then
-    CXXFLAGS="-O"
+if test $cl_cv_have_attr_flatten = yes; then
+  AC_DEFINE(CL_HAVE_ATTRIBUTE_FLATTEN, ,[Define if compiler supports __attribute__((flatten))])
 fi
 ])