[PATCH libffi 0/4] Robustify compiler and library path selection in the testsuite

[Maciej W. Rozycki]

Hi,

 In the course of a discussion at one of the GCC mailing lists here: 
<https://gcc.gnu.org/pipermail/gcc-patches/2020-March/542761.html> I have 
realised that some parts related to libffi testing have not been merged to 
GCC, and they are needed to choose the right compiler in a cross-compiler 
build environment where the build root option has been used.

 Additionally the right target run-time loader's library path has to be 
set via the LD_LIBRARY_PATH environment variable for running the test 
suite in a cross-compilation environment where the location of the host 
libraries is obviously irrelevant.

 We are keen to keep the GCC's copy of libffi as close as possible to the 
upstream version however while usable the current solution has some issues 
which we would rather avoid.  I have therefore decided to address some of 
them with the intent to have the result backported to GCC.  As it stands 
I'm told the current version of libffi cannot be fully merged to GCC, as 
there have been an ABI change that will require technical evaluation.  So 
the intent has been to backport the changes proposed here individually.

 See the individual change descriptions and any further discussion 
included for full details of each patch proposed.

 These changes have been regression-tested with the `x86_64-linux-gnu' 
native configuration, and also the `x86_64-linux-gnu' host and the 
`riscv64-linux-gnu' target using RISC-V QEMU in the Linux user emulation 
mode as the target board.  In the latter case I actually dropped libffi 
into GCC as a replacement of the version included there, with a minor 
update like below (+script regeneration) to add multilib support.

 Any questions, comments, or concerns?  Otherwise, please apply.

  Maciej

Index: gcc/libffi/Makefile.am
===================================================================
--- gcc.orig/libffi/Makefile.am
+++ gcc/libffi/Makefile.am
@@ -2,7 +2,7 @@
 
 AUTOMAKE_OPTIONS = foreign subdir-objects
 
-ACLOCAL_AMFLAGS = -I m4
+ACLOCAL_AMFLAGS = -I m4 -I ../config
 
 SUBDIRS = include testsuite man
 if BUILD_DOCS
@@ -158,3 +158,12 @@ AM_CCASFLAGS = $(AM_CPPFLAGS)
 	if [ -d $(top_srcdir)/.git ] ; then (cd $(top_srcdir); git log --no-decorate) ; else echo 'See git log for history.' ; fi > $(distdir)/ChangeLog
 	s=`awk '/was released on/{ print NR; exit}' $(top_srcdir)/README.md`; tail -n +$$(($$s-1)) $(top_srcdir)/README.md > $(distdir)/README.md
 
+# Multilib support.  Automake should provide these on its own.
+all-recursive: all-multi
+install-recursive: install-multi
+mostlyclean-recursive: mostlyclean-multi
+clean-recursive: clean-multi
+distclean-recursive: distclean-multi
+maintainer-clean-recursive: maintainer-clean-multi
+
+include $(top_srcdir)/../multilib.am
Index: gcc/libffi/configure.ac
===================================================================
--- gcc.orig/libffi/configure.ac
+++ gcc/libffi/configure.ac
@@ -5,6 +5,8 @@ AC_PREREQ(2.68)
 AC_INIT([libffi], [3.3], [http://github.com/libffi/libffi/issues])
 AC_CONFIG_HEADERS([fficonfig.h])
 
+AM_ENABLE_MULTILIB(, ..)
+
 AC_CANONICAL_SYSTEM
 target_alias=${target_alias-$host_alias}