RFC: Always build libgcc_eh.a

[Daniel Jacobowitz <drow at false dot org>]

I'm not 100% sure this patch is a good idea, but it would be convenient for
me.  All comments appreciated.

The problem I'm trying to solve is an inconsistency between two i386-linux
toolchains; one configured with --enable-shared and one configured with
--disable-shared.  In the --enable-shared configuration we have:

  libgcc.a	-	Support routines, not including EH
  libgcc_eh.a	-	EH support routines
  libgcc_s.so	-	Support routines, including EH

In the --disable-shared configuration we have:

  libgcc.a	-	That's all you get, folks - all routines

When building glibc, there are a couple of places where it needs to pick up
a static copy of libgcc, including EH.  Since we're building the C library,
glibc uses -nostdlib and links everything it needs explicitly.  That means
it needs to know whether libgcc_eh.a is available.

The first thing I tried was to check for libgcc_eh.a during configure.  That
works, but my normal process is to build a --disable-shared toolchain, then
glibc, then an --enable-shared toolchain.  When I go back to my glibc
working directory, I can't rebuild glibc any more.  It only pulls in
libgcc.a, and the EH routines are now missing.

This patch half solves the problem, by creating a dummy libgcc_eh.a.  A
better solution IMO is to _always_ put the EH routines in libgcc_eh.a; I
took a stab at that, but since it involves always linking in -lgcc_eh even
when --disable-shared, I think it is too invasive for 4.0.  And target
headers do some very strange things with LIBGCC_SPEC.

I think that making the set of libraries we provide more consistent across
configurations is valuable, even if nothing will link this library by
default.  OK?

-- 
Daniel Jacobowitz
CodeSourcery, LLC

2005-02-11  Daniel Jacobowitz  <dan@codesourcery.com>

	* gcc/mklibgcc.in: Always create libgcc_eh.a.

Index: gcc/gcc/mklibgcc.in
===================================================================
--- gcc.orig/gcc/mklibgcc.in	2005-02-11 12:50:18.762611520 -0500
+++ gcc/gcc/mklibgcc.in	2005-02-11 13:34:48.117472630 -0500
@@ -597,6 +597,17 @@ for ml in $MULTILIBS; do
       echo "	$gcc_compile" $flags -fexceptions '$(vis_hide)' -c $file -o $out
       echo $libgcc_a: $out
     done
+
+    # Create an empty libgcc_eh.a for consistency.  It would be better
+    # to put the routines from LIB2ADDEH in it, but that would require
+    # even more surgery on LIBGCC_SPEC.
+    file=libgcc/${dir}/libgcc_eh.c
+    out=libgcc/${dir}/libgcc_eh${objext}
+    echo "${dir}/libgcc_eh.a: ${out}"
+    echo "${out}: stmp-dirs ${file}"
+    echo "	$gcc_compile" $flags -c ${file} -o ${out}
+    echo "${file}: stmp-dirs"
+    echo "	echo 'static int unused __attribute__((unused));' > ${file}"
   fi
 
   # Again, this does not handle assembly.
@@ -740,14 +751,12 @@ EOF
     echo "all: $libunwind_a"
   fi
 
-  if [ "$libgcc_eh_a" ]; then
-    echo ""
-    echo "${dir}/libgcc_eh.a: stmp-dirs"
-    echo "	-rm -f ${dir}/libgcc_eh.a"
-    echo '	$(AR_CREATE_FOR_TARGET)' ${dir}/libgcc_eh.a '$(objects)'
-    echo '	$(RANLIB_FOR_TARGET)' ${dir}/libgcc_eh.a
-    echo "all: $libgcc_eh_a"
-  fi
+  echo ""
+  echo "${dir}/libgcc_eh.a: stmp-dirs"
+  echo "	-rm -f ${dir}/libgcc_eh.a"
+  echo '	$(AR_CREATE_FOR_TARGET)' ${dir}/libgcc_eh.a '$(objects)'
+  echo '	$(RANLIB_FOR_TARGET)' ${dir}/libgcc_eh.a
+  echo "all: ${dir}/libgcc_eh.a"
 
   # Shared libraries.
   if [ "$libgcc_s_so" ]; then
@@ -815,10 +824,10 @@ for ml in $MULTILIBS; do
   echo '	$(INSTALL_DATA)' ${dir}/libgcov.a ${ldir}/
   echo '	$(RANLIB_FOR_TARGET)' ${ldir}/libgcov.a
 
-  if [ "$SHLIB_LINK" ]; then
-    echo '	$(INSTALL_DATA)' ${dir}/libgcc_eh.a ${ldir}/
-    echo '	$(RANLIB_FOR_TARGET)' ${ldir}/libgcc_eh.a
+  echo '	$(INSTALL_DATA)' ${dir}/libgcc_eh.a ${ldir}/
+  echo '	$(RANLIB_FOR_TARGET)' ${ldir}/libgcc_eh.a
 
+  if [ "$SHLIB_LINK" ]; then
     if [ "$dir" = . ]; then
       shlib_base_name=libgcc_s
       shlibunwind_base_name=libunwind