[Mesa-stable] [PATCH 3/7] configure.ac: rework llvm libs handling for 3.9+

[Emil Velikov]

From: Emil Velikov <emil.velikov at collabora.com>

Earlier versions need different quirks, but as of LLVM 3.9 llvm-config
provides --link-shared/link-static toggles.

The output of which seems to be reliable - looking at LLVM 3.9, 4.0 and
5.0.

Note that there are earlier code will be used for pre LLVM 3.9 and is
unchanged.

This effectively fixes LLVM static linking, while providing a clearer
and more robust solution for future versions.

Mildly interesting side notes:

 - build-mode (introduced with 3.8) was buggy with 3.8
It shows "static" when build with -DLLVM_LINK_LLVM_DYLIB=ON, yet it was
consistent with --libs. The latter shows the static libraries.

 - libnames and libfiles are broken with LVM 3.9
The library prefix and extension is printed twice liblibLLVM-3.9.so.so

Cc: mesa-stable at lists.freedesktop.org
Cc: Dieter Nützel <Dieter at nuetzel-hh.de>
Cc: Michel Dänzer <michel.daenzer at amd.com>
Signed-off-by: Emil Velikov <emil.velikov at collabora.com>
---
 configure.ac | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/configure.ac b/configure.ac
index 308938a5a88..dbaa6569e4e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2684,18 +2684,27 @@ if test "x$enable_llvm" = xyes; then
     dnl this was causing the same libraries to be appear multiple times
     dnl in LLVM_LIBS.
 
-    LLVM_LIBS="`$LLVM_CONFIG --libs ${LLVM_COMPONENTS}`"
-
-    if test "x$enable_llvm_shared_libs" = xyes; then
-        if test $LLVM_VERSION_MAJOR -lt 4 -o "`$LLVM_CONFIG --shared-mode ${LLVM_COMPONENTS}`" = static; then
-            detect_old_buggy_llvm
+    if test $LLVM_VERSION_MAJOR -ge 4 -o $LLVM_VERSION_MAJOR -eq 3 -a $LLVM_VERSION_MINOR -ge 9; then
+        if test "x$enable_llvm_shared_libs" = xyes; then
+            LLVM_LIBS="`$LLVM_CONFIG --link-shared --libs ${LLVM_COMPONENTS}`"
+        else
+            LLVM_LIBS="`$LLVM_CONFIG --link-static --libs ${LLVM_COMPONENTS} --system-libs`"
+            dnl llvm-config lists the system libs on a separate line. While
+            dnl invoking --system-libs without --link-static assumes shared link.
+            dnl Everybody now, say - Thank you LLVM developers
+            LLVM_LIBS="`echo $LLVM_LIBS | $SED 's/\n//g'`"
         fi
     else
-        AC_MSG_WARN([Building mesa with statically linked LLVM may cause compilation issues])
-        dnl We need to link to llvm system libs when using static libs
-        dnl However, only llvm 3.5+ provides --system-libs
-        if test $LLVM_VERSION_MAJOR -ge 4 -o $LLVM_VERSION_MAJOR -eq 3 -a $LLVM_VERSION_MINOR -ge 5; then
-            LLVM_LIBS="$LLVM_LIBS `$LLVM_CONFIG --system-libs`"
+        LLVM_LIBS="`$LLVM_CONFIG --libs ${LLVM_COMPONENTS}`"
+        if test "x$enable_llvm_shared_libs" = xyes; then
+            detect_old_buggy_llvm
+        else
+            AC_MSG_WARN([Building mesa with statically linked LLVM may cause compilation issues])
+            dnl We need to link to llvm system libs when using static libs
+            dnl However, only llvm 3.5+ provides --system-libs
+            if test $LLVM_VERSION_MAJOR -ge 4 -o $LLVM_VERSION_MAJOR -eq 3 -a $LLVM_VERSION_MINOR -ge 5; then
+                LLVM_LIBS="$LLVM_LIBS `$LLVM_CONFIG --system-libs`"
+            fi
         fi
     fi
 fi
-- 
2.14.1