[omniORB] Static build with GCC 3.4

[Vladimir Panov]

Hi.

When omniORB 4.0.5 (or any 4.0 version, actually) is built with GCC 3.4, 
then a statically linked program against it segfaults on startup. The 
reason is that the static initializers of the code sets are not executed 
(even the ones from libomniORB4.a, not only the ones from 
libomniCodeSets4.a). The reason seems to be a new optimization in GCC 
3.4 called "unit-at-a-time" which is on by default when using -O2.
As far as I understood, this optimization considers the static 
initilizers to be dead code, and GCC doesn't even generate machine code 
for them, let alone run them. I tried to fix this in the source 
(including the advised way of using the "used" attribute) but miserably 
failed. Of course, there should be a way to achieve this in the source 
somehow and this would be the best solution.
Another solution is to use -fno-unit-at-a-time, and I have attached a 
patch for it against omniORB 4.0.5 (don't forget to run autoreconf after 
you apply it). But this should be considered a temporary solution 
because the option might be dropped in the future.
Here is the GCC 3.4's changelog which gives some information about the 
unit-at-a-time optimization:
http://gcc.gnu.org/gcc-3.4/changes.html

Vlado

-------------- next part --------------
diff -r -u omniORB-4.0.5-orig/acinclude.m4 omniORB-4.0.5/acinclude.m4
--- omniORB-4.0.5-orig/acinclude.m4	2004-10-17 23:14:25.000000000 +0300
+++ omniORB-4.0.5/acinclude.m4	2005-02-06 22:23:57.000000000 +0200
@@ -470,3 +470,14 @@
 fi
 ])
 
+AC_DEFUN([OMNI_CHECK_NO_UNIT_AT_A_TIME],
+[AC_CACHE_CHECK(whether $CC accepts -fno-unit-at-a-time,
+omni_cv_no_unit_at_a_time,
+[
+    AC_LANG_PUSH(C)
+    save_CFLAGS=$CFLAGS
+    CFLAGS="$CFLAGS -fno-unit-at-a-time"
+    AC_COMPILE_IFELSE(AC_LANG_PROGRAM(,), omni_cv_no_unit_at_a_time="yes", omni_cv_no_unit_at_a_time="no")
+    CFLAGS=$save_CFLAGS
+    AC_LANG_POP
+])])
diff -r -u omniORB-4.0.5-orig/configure.ac omniORB-4.0.5/configure.ac
--- omniORB-4.0.5-orig/configure.ac	2004-10-18 03:44:55.000000000 +0300
+++ omniORB-4.0.5/configure.ac	2005-02-06 23:02:15.000000000 +0200
@@ -26,6 +26,12 @@
 
 AC_LANG(C++)
 
+OMNI_CHECK_NO_UNIT_AT_A_TIME
+if test "x$omni_cv_no_unit_at_a_time" = "xyes"
+then
+  EXTRA_GCC_CXXFLAGS="-fno-unit-at-a-time"
+fi
+AC_SUBST(EXTRA_GCC_CXXFLAGS)
 
 dnl ** Libraries
 
diff -r -u omniORB-4.0.5-orig/mk/beforeauto.mk.in omniORB-4.0.5/mk/beforeauto.mk.in
--- omniORB-4.0.5-orig/mk/beforeauto.mk.in	2004-10-18 03:44:56.000000000 +0300
+++ omniORB-4.0.5/mk/beforeauto.mk.in	2005-02-06 23:00:46.000000000 +0200
@@ -733,7 +733,7 @@
 ifdef Compiler_GCC
 CMAKEDEPEND     += -D__GNUC__
 CXXMAKEDEPEND   += -D__GNUG__ -D__GNUC__
-CXXOPTIONS       = -Wall -Wno-unused -fexceptions
+CXXOPTIONS       = -Wall -Wno-unused -fexceptions @EXTRA_GCC_CXXFLAGS@
 EgcsMajorVersion = 1
 EgcsMinorVersion = 1
 SHAREDLIB_CPPFLAGS = -fPIC