Build shared LLVM things correctly with library dependencies

src/SConscript

@@ -80,6 +80,52 @@ ctests = ['t_benchmark.c',
           't_misc.c',
 	  't_regression.c']
 
+# some llvm versions are old and will not work; some require --system-libs
+# with llvm-config, and some will break if given it
+llvm_config_version = subprocess.Popen('%s --version' % env["LLVM_CONFIG"], \
+                                       shell=True, \
+                                       stdin=subprocess.PIPE, stdout=subprocess.PIPE).communicate()
+if LooseVersion(llvm_config_version[0]) < LooseVersion("3.6"):
+   print "This LLVM version %s is too old" % llvm_config_version
+   Exit(1)
+
+if LooseVersion(llvm_config_version[0]) < LooseVersion("3.9") and \
+   LooseVersion(llvm_config_version[0]) >= LooseVersion("3.5"):
+    llvm_system_libs_flag = "--system-libs"
+else:
+    llvm_system_libs_flag = ""
+
+# Only keep one copy of this
+required_llvm_components = "core executionengine mcjit analysis x86codegen x86info"
+# Stubbing this out so we can implement static-only mode if needed later
+use_shared_llvm = True
+# Can we ask for shared/static from llvm-config?
+if LooseVersion(llvm_config_version[0]) < LooseVersion("3.9"):
+    # Nope
+    llvm_linkage_type_flag = ""
+    llvm_use_computed_shared_lib_name = True
+else:
+    # Woo, they finally fixed the dumb
+    llvm_use_computed_shared_lib_name = False
+    if use_shared_llvm:
+        llvm_linkage_type_flag = "--link-shared"
+    else:
+        llvm_linkage_type_flag = "--link-static"
+
+if llvm_use_computed_shared_lib_name:
+    # Okay, pull out the major and minor version numbers (barf barf)
+    p = re.compile("^(\d+)\.(\d+).*$")
+    m = p.match(llvm_config_version[0])
+    if m:
+        llvm_computed_shared_lib_name = "LLVM-%d.%d" % ((int)(m.group(1)), (int)(m.group(2)))
+    else:
+        print "Couldn't compute shared library name from LLVM version '%s', but needed to" % \
+            llvm_config_version[0]
+        Exit(1)
+else:
+    # We won't be needing it
+    llvm_computed_shared_lib_name = None
+
 # llvm-config 'helpfully' supplies -g and -O flags; educate it with this
 # custom ParseConfig function arg
 
@@ -94,8 +140,30 @@ def llvm_config_sanitize(env, cmd, unique=1):
     env.MergeFlags(filtered_cmd, unique)
 
 env.ParseConfig('%s --cflags --ldflags' % env["LLVM_CONFIG"], function=llvm_config_sanitize)
-libhammer_shared = env.SharedLibrary('hammer', parsers + backends + misc_hammer_parts)
 libhammer_static = env.StaticLibrary('hammer', parsers + backends + misc_hammer_parts)
+
+# Use a cloned env for the shared library so we can have library dependencies
+shared_env = env.Clone()
+# Get LLVM stuff into LIBS/LDFLAGS
+shared_env.ParseConfig('%s --ldflags %s %s %s' % \
+                       (env["LLVM_CONFIG"], llvm_system_libs_flag, llvm_linkage_type_flag, required_llvm_components), \
+                       function=llvm_config_sanitize)
+# Get the right -l lines in
+if use_shared_llvm:
+    if llvm_use_computed_shared_lib_name:
+        shared_env.Append(LIBS=[llvm_computed_shared_lib_name, ])
+    else:
+        shared_env.ParseConfig('%s %s --libs %s' % \
+                               (env["LLVM_CONFIG"], llvm_linkage_type_flag, required_llvm_components), \
+                               function=llvm_config_sanitize)
+else:
+    # Just grab the statics regardless of version
+    shared_env.ParseConfig('%s %s --libs %s' % \
+                           (env["LLVM_CONFIG"], llvm_linkage_type_flag, required_llvm_components), \
+                           function=llvm_config_sanitize)
+shared_env.Append(LIBS=['stdc++', ], LIBPATH=['.'])
+libhammer_shared = shared_env.SharedLibrary('hammer', parsers + backends + misc_hammer_parts)
+
 Default(libhammer_shared, libhammer_static)
 
 env.Install("$libpath", [libhammer_static, libhammer_shared])
@@ -107,22 +175,23 @@ env.Install("$pkgconfigpath", "../../../libhammer.pc")
 testenv = env.Clone()
 testenv.Append(LIBS=['hammer'], LIBPATH=['.'])
 testenv.ParseConfig('pkg-config --cflags --libs glib-2.0')
-testenv_llvm_config_version = subprocess.Popen('%s --version' % env["LLVM_CONFIG"], \
-                                               shell=True, \
-                                               stdin=subprocess.PIPE, stdout=subprocess.PIPE).communicate()
-
-if LooseVersion(testenv_llvm_config_version[0]) < LooseVersion("3.6"):
-   print "This LLVM version %s is too old" % testenv_llvm_config_version
-   Exit(1)
-
-if LooseVersion(testenv_llvm_config_version[0]) < LooseVersion("3.9") and \
-   LooseVersion(testenv_llvm_config_version[0]) >= LooseVersion("3.5"):
-    testenv_llvm_system_libs_flag = "--system-libs"
+# Get LLVM stuff into LIBS/LDFLAGS
+testenv.ParseConfig('%s --ldflags %s %s %s' % \
+                    (env["LLVM_CONFIG"], llvm_system_libs_flag, llvm_linkage_type_flag, required_llvm_components), \
+                    function=llvm_config_sanitize)
+# Get the right -l lines in
+if use_shared_llvm:
+    if llvm_use_computed_shared_lib_name:
+        testenv.Append(LIBS=[llvm_computed_shared_lib_name, ])
+    else:
+        testenv.ParseConfig('%s %s --libs %s' % \
+                            (env["LLVM_CONFIG"], llvm_linkage_type_flag, required_llvm_components), \
+                            function=llvm_config_sanitize)
 else:
-    testenv_llvm_system_libs_flag = ""
-
-testenv.ParseConfig('%s --cflags --ldflags --libs %s core executionengine mcjit analysis x86codegen x86info' % \
-                    (env["LLVM_CONFIG"], testenv_llvm_system_libs_flag), function=llvm_config_sanitize)
+    # Just grab the statics regardless of version
+    testenv.ParseConfig('%s %s --libs %s' % \
+                        (env["LLVM_CONFIG"], llvm_linkage_type_flag, required_llvm_components), \
+                        function=llvm_config_sanitize)
 testenv.Append(LIBS=['stdc++'], LIBPATH=['.'])
 ctestexec = testenv.Program('test_suite', ctests + ['test_suite.c'], LINKFLAGS="--coverage" if testenv.GetOption("coverage") else None)
 ctest = Alias('testc', [ctestexec], "".join(["env LD_LIBRARY_PATH=", os.path.dirname(ctestexec[0].path), " ", ctestexec[0].path]))