[Mesa-dev] [PATCH] configure: Trust LLVM >= 4.0 llvm-config --libs for shared libraries

[Michel Dänzer]

From: Michel Dänzer <michel.daenzer at amd.com>

No need to manually look for the library files anymore with current
LLVM. This sidesteps the manual method failing when LLVM was built with
-DLLVM_APPEND_VC_REV=ON.

(This might already work with older versions of LLVM)

Signed-off-by: Michel Dänzer <michel.daenzer at amd.com>
---
 configure.ac | 58 ++++++++++++++++++++++++++++++----------------------------
 1 file changed, 30 insertions(+), 28 deletions(-)

diff --git a/configure.ac b/configure.ac
index 5b12dd8506..4992e9538f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2623,35 +2623,37 @@ if test "x$enable_llvm" = xyes; then
     fi
     LLVM_LIBS="`$LLVM_CONFIG --libs ${LLVM_COMPONENTS}`"
 
-    dnl llvm-config may not give the right answer when llvm is a built as a
-    dnl single shared library, so we must work the library name out for
-    dnl ourselves.
-    dnl (See https://llvm.org/bugs/show_bug.cgi?id=6823)
     if test "x$enable_llvm_shared_libs" = xyes; then
-        dnl We can't use $LLVM_VERSION because it has 'svn' stripped out,
-        LLVM_SO_NAME=LLVM-`$LLVM_CONFIG --version`
-        AS_IF([test -f "$LLVM_LIBDIR/lib$LLVM_SO_NAME.$IMP_LIB_EXT"], [llvm_have_one_so=yes])
-
-        if test "x$llvm_have_one_so" = xyes; then
-            dnl LLVM was built using auto*, so there is only one shared object.
-            LLVM_LIBS="-l$LLVM_SO_NAME"
-        else
-            dnl If LLVM was built with CMake, there will be one shared object per
-            dnl component.
-            AS_IF([test ! -f "$LLVM_LIBDIR/libLLVMTarget.$IMP_LIB_EXT"],
-                    [AC_MSG_ERROR([Could not find llvm shared libraries:
-	Please make sure you have built llvm with the --enable-shared option
-	and that your llvm libraries are installed in $LLVM_LIBDIR
-	If you have installed your llvm libraries to a different directory you
-	can use the --with-llvm-prefix= configure flag to specify this directory.
-	NOTE: Mesa is attempting to use llvm shared libraries by default.
-	If you do not want to build with llvm shared libraries and instead want to
-	use llvm static libraries then add --disable-llvm-shared-libs to your configure
-	invocation and rebuild.])])
-
-           dnl We don't need to update LLVM_LIBS in this case because the LLVM
-           dnl install uses a shared object for each component and we have
-           dnl already added all of these objects to LLVM_LIBS.
+        if test $LLVM_VERSION_MAJOR -lt 4; then
+            dnl llvm-config may not give the right answer when llvm is a built as a
+            dnl single shared library, so we must work the library name out for
+            dnl ourselves.
+            dnl (See https://llvm.org/bugs/show_bug.cgi?id=6823)
+            dnl We can't use $LLVM_VERSION because it has 'svn' stripped out,
+            LLVM_SO_NAME=LLVM-`$LLVM_CONFIG --version`
+            AS_IF([test -f "$LLVM_LIBDIR/lib$LLVM_SO_NAME.$IMP_LIB_EXT"], [llvm_have_one_so=yes])
+
+            if test "x$llvm_have_one_so" = xyes; then
+               dnl LLVM was built using auto*, so there is only one shared object.
+               LLVM_LIBS="-l$LLVM_SO_NAME"
+            else
+                dnl If LLVM was built with CMake, there will be one shared object per
+                dnl component.
+                AS_IF([test ! -f "$LLVM_LIBDIR/libLLVMTarget.$IMP_LIB_EXT"],
+                      [AC_MSG_ERROR([Could not find llvm shared libraries:
+                       Please make sure you have built llvm with the --enable-shared option
+                       and that your llvm libraries are installed in $LLVM_LIBDIR
+                       If you have installed your llvm libraries to a different directory you
+                       can use the --with-llvm-prefix= configure flag to specify this directory.
+                       NOTE: Mesa is attempting to use llvm shared libraries by default.
+                       If you do not want to build with llvm shared libraries and instead want to
+                       use llvm static libraries then add --disable-llvm-shared-libs to your configure
+                       invocation and rebuild.])])
+
+                dnl We don't need to update LLVM_LIBS in this case because the LLVM
+                dnl install uses a shared object for each component and we have
+                dnl already added all of these objects to LLVM_LIBS.
+            fi
         fi
     else
         AC_MSG_WARN([Building mesa with statically linked LLVM may cause compilation issues])
-- 
2.13.3