autoconf: Attempt to figure out the PIC flags for the platform

This commit adds an autoconf macro, MESA_PIC_FLAGS, which sets the
PIC flags according to platform and static/shared setting. The platform
specifics are taken straight from libtool.m4 and stripped down to just
the flags and platforms we cover in Mesa. This should hopefully make it
possible to use autoconf on non-GCC platforms.

The macro is added external to configure.ac in acinclude.m4 since it's
pretty bloated.

Note to BSDers: Previously, x86 defaulted to non-PIC on FreeBSD. I
didn't carry that preference into this macro. Instead, you can just use
--disable-pic where desired.

3 files changed, 125 insertions, 17 deletions

diff --git a/Makefile b/Makefile
index 96d3885849..4668443b77 100644
--- a/Makefile
+++ b/Makefile
@@ -191,6 +191,7 @@ MAIN_FILES = \
 	$(DIRECTORY)/Makefile*						\
 	$(DIRECTORY)/configure						\
 	$(DIRECTORY)/configure.ac					\
+	$(DIRECTORY)/acinclude.m4					\
 	$(DIRECTORY)/aclocal.m4						\
 	$(DIRECTORY)/descrip.mms					\
 	$(DIRECTORY)/mms-config.					\
@@ -455,9 +456,9 @@ ACLOCAL = aclocal
 ACLOCAL_FLAGS =
 AUTOCONF = autoconf
 AC_FLAGS =
-aclocal.m4: configure.ac
+aclocal.m4: configure.ac acinclude.m4
 	$(ACLOCAL) $(ACLOCAL_FLAGS)
-configure: configure.ac aclocal.m4
+configure: configure.ac aclocal.m4 acinclude.m4
 	$(AUTOCONF) $(AC_FLAGS)
 
 rm_depend:
diff --git a/acinclude.m4 b/acinclude.m4
new file mode 100644
index 0000000000..a5b389d5da
--- /dev/null
+++ b/acinclude.m4
@@ -0,0 +1,119 @@
+# A few convenience macros for Mesa, mostly to keep all the platform
+# specifics out of configure.ac.
+
+# MESA_PIC_FLAGS()
+#
+# Find out whether to build PIC code using the option --enable-pic and
+# the configure enable_static/enable_shared settings. If PIC is needed,
+# figure out the necessary flags for the platform and compiler.
+#
+# The platform checks have been shamelessly taken from libtool and
+# stripped down to just what's needed for Mesa. See _LT_COMPILER_PIC in
+# /usr/share/aclocal/libtool.m4 or
+# http://git.savannah.gnu.org/gitweb/?p=libtool.git;a=blob;f=libltdl/m4/libtool.m4;hb=HEAD
+#
+AC_DEFUN([MESA_PIC_FLAGS],
+[AC_REQUIRE([AC_PROG_CC])dnl
+AC_ARG_VAR([PIC_FLAGS], [compiler flags for PIC code])
+AC_ARG_ENABLE([pic],
+    [AS_HELP_STRING([--disable-pic],
+        [compile PIC objects @<:@default=enabled for shared builds
+        on supported platforms@:>@])],
+    [enable_pic="$enableval"
+    test "x$enable_pic" = x && enable_pic=auto],
+    [enable_pic=auto])
+# disable PIC by default for static builds
+if test "$enable_pic" = auto && test "$enable_static" = yes; then
+    enable_pic=no
+fi
+# if PIC hasn't been explicitly disabled, try to figure out the flags
+if test "$enable_pic" != no; then
+    AC_MSG_CHECKING([for $CC option to produce PIC])
+    # allow the user's flags to override
+    if test "x$PIC_FLAGS" = x; then
+        # see if we're using GCC
+        if test "x$GCC" = xyes; then
+            case "$host_os" in
+            aix*|beos*|cygwin*|irix5*|irix6*|osf3*|osf4*|osf5*)
+                # PIC is the default for these OSes.
+                ;;
+            mingw*|os2*|pw32*)
+                # This hack is so that the source file can tell whether
+                # it is being built for inclusion in a dll (and should
+                # export symbols for example).
+                PIC_FLAGS="-DDLL_EXPORT"
+                ;;
+            darwin*|rhapsody*)
+                # PIC is the default on this platform
+                # Common symbols not allowed in MH_DYLIB files
+                PIC_FLAGS="-fno-common"
+                ;;
+            hpux*)
+                # PIC is the default for IA64 HP-UX and 64-bit HP-UX,
+                # but not for PA HP-UX.
+                case $host_cpu in
+                hppa*64*|ia64*)
+                    ;;
+                *)
+                    PIC_FLAGS="-fPIC"
+                    ;;
+                esac
+                ;;
+            *)
+                # Everyone else on GCC uses -fPIC
+                PIC_FLAGS="-fPIC"
+                ;;
+            esac
+        else # !GCC
+            case "$host_os" in
+            hpux9*|hpux10*|hpux11*)
+                # PIC is the default for IA64 HP-UX and 64-bit HP-UX,
+                # but not for PA HP-UX.
+                case "$host_cpu" in
+                hppa*64*|ia64*)
+                    # +Z the default
+                    ;;
+                *)
+                    PIC_FLAGS="+Z"
+                    ;;
+                esac
+                ;;
+            linux*|k*bsd*-gnu)
+                case `basename "$CC"` in
+                icc*|ecc*|ifort*)
+                    PIC_FLAGS="-KPIC"
+                    ;;
+                pgcc*|pgf77*|pgf90*|pgf95*)
+                    # Portland Group compilers (*not* the Pentium gcc
+                    # compiler, which looks to be a dead project)
+                    PIC_FLAGS="-fpic"
+                    ;;
+                ccc*)
+                    # All Alpha code is PIC.
+                    ;;
+                xl*)
+                    # IBM XL C 8.0/Fortran 10.1 on PPC
+                    PIC_FLAGS="-qpic"
+                    ;;
+                *)
+                    case `$CC -V 2>&1 | sed 5q` in
+                    *Sun\ C*|*Sun\ F*)
+                        # Sun C 5.9 or Sun Fortran
+                        PIC_FLAGS="-KPIC"
+                        ;;
+                    esac
+                esac
+                ;;
+            solaris*)
+                PIC_FLAGS="-KPIC"
+                ;;
+            sunos4*)
+                PIC_FLAGS="-PIC"
+                ;;
+            esac
+        fi # GCC
+    fi # PIC_FLAGS
+    AC_MSG_RESULT([$PIC_FLAGS])
+fi
+AC_SUBST([PIC_FLAGS])
+])# MESA_PIC_FLAGS
diff --git a/configure.ac b/configure.ac
index cccf7bd44d..e57f7b7de6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -879,21 +879,9 @@ AC_SUBST([ASM_FLAGS])
 AC_SUBST([ASM_SOURCES])
 AC_SUBST([ASM_API])
 
-PIC_FLAGS=""
-case "$host_os" in
-linux*)
-    PIC_FLAGS="-fPIC"
-    ;;
-freebsd* | dragonfly*)
-    PIC_FLAGS="-fPIC"
-    case "$host_cpu" in
-    i?86)
-        PIC_FLAGS=""
-        ;;
-    esac
-    ;;
-esac
-AC_SUBST([PIC_FLAGS])
+dnl PIC code macro
+MESA_PIC_FLAGS
+
 
 dnl Restore LDFLAGS and CPPFLAGS
 LDFLAGS="$_SAVE_LDFLAGS"