Index: polly/trunk/CMakeLists.txt
===================================================================
--- polly/trunk/CMakeLists.txt
+++ polly/trunk/CMakeLists.txt
@@ -88,9 +88,33 @@
     endif()
   endif()
 
+  # Sources available, too?
+  execute_process(COMMAND "${LLVM_INSTALL_ROOT}/bin/llvm-config" --src-root
+                  OUTPUT_VARIABLE MAIN_SRC_DIR
+                  OUTPUT_STRIP_TRAILING_WHITESPACE)
+  set(LLVM_SOURCE_ROOT ${MAIN_SRC_DIR} CACHE PATH "Path to LLVM source tree")
+
+  # Enable unit tests if available.
+  set(UNITTEST_DIR ${LLVM_SOURCE_ROOT}/utils/unittest)
+  if(EXISTS ${UNITTEST_DIR}/googletest/include/gtest/gtest.h)
+    add_library(gtest ${UNITTEST_DIR}/googletest/src/gtest-all.cc)
+    target_include_directories(gtest PUBLIC "${UNITTEST_DIR}/googletest/include" PRIVATE "${UNITTEST_DIR}/googletest")
+    if( NOT MSVC )
+      target_link_libraries(gtest pthread tinfo dl)
+    endif ()
+
+    add_library(gtest_main ${UNITTEST_DIR}/UnitTestMain/TestMain.cpp)
+    target_link_libraries(gtest_main gtest)
+
+    set(POLLY_GTEST_AVAIL 1)
+  endif()
+
   # Make sure the isl c files are built as fPIC
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC")
-endif(NOT DEFINED LLVM_MAIN_SRC_DIR)
+else ()
+  set(LLVM_SOURCE_ROOT "${LLVM_MAIN_SRC_DIR}")
+  set(POLLY_GTEST_AVAIL 1)
+endif ()
 
 set(POLLY_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 set(POLLY_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
@@ -169,6 +193,9 @@
 add_subdirectory(docs)
 add_subdirectory(lib)
 add_subdirectory(test)
+if (POLLY_GTEST_AVAIL)
+  add_subdirectory(unittests)
+endif ()
 add_subdirectory(tools)
 # TODO: docs.
 
@@ -177,7 +204,7 @@
                 ${POLLY_BINARY_DIR}/include/polly/Config/config.h )
 
 # Add target to check formatting of polly files
-file( GLOB_RECURSE files *.h lib/*.cpp lib/*.c tools/*.cpp tools/*.c tools/*.h)
+file( GLOB_RECURSE files *.h lib/*.cpp lib/*.c tools/*.cpp tools/*.c tools/*.h unittests/*.cpp)
 file( GLOB_RECURSE jsonfiles lib/JSON/*.h lib/JSON/*.cpp)
 file( GLOB_RECURSE external lib/External/*.h lib/External/*.c)
 list( REMOVE_ITEM files ${jsonfiles} ${external})
Index: polly/trunk/test/CMakeLists.txt
===================================================================
--- polly/trunk/test/CMakeLists.txt
+++ polly/trunk/test/CMakeLists.txt
@@ -18,6 +18,9 @@
   # FIXME: FileCheck is not available in llvm install directory at the moment.
   set(LLVM_LIT ${LLVM_INSTALL_ROOT}/bin/llvm-lit)
   set(POLLY_TEST_DEPS LLVMPolly)
+  if (POLLY_GTEST_AVAIL)
+    list(APPEND POLLY_TEST_DEPS PollyUnitTests)
+  endif ()
 
   set(LLVM_BINARY_DIR "${LLVM_INSTALL_ROOT}")
   set(LLVM_TOOLS_DIR "${LLVM_INSTALL_ROOT}/bin")
@@ -67,18 +70,38 @@
     add_custom_target(check-polly
       COMMAND ${LLVM_LIT}
                   --param polly_site_config=${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg
+                  --param polly_unit_site_config=${CMAKE_CURRENT_BINARY_DIR}/Unit/lit.site.cfg
                   --param build_config=${CMAKE_CFG_INTDIR}
                   -sv ${POLLY_TEST_EXTRA_ARGS}
                   ${CMAKE_CURRENT_BINARY_DIR}
                   DEPENDS ${POLLY_TEST_DEPS}
-                  COMMENT "Running Polly regression tests")
+                  COMMENT "Running Polly regression/unit tests")
     set_target_properties(check-polly PROPERTIES FOLDER "Polly")
+
+    if (POLLY_GTEST_AVAIL)
+      configure_file(
+        ${CMAKE_CURRENT_SOURCE_DIR}/Unit/lit.site.cfg.in
+        ${CMAKE_CURRENT_BINARY_DIR}/Unit/lit.site.cfg)
+
+      add_custom_target(check-polly-unittests
+        COMMAND ${LLVM_LIT}
+                  --param polly_site_config=${CMAKE_CURRENT_BINARY_DIR}/Unit/lit.site.cfg
+                  --param build_config=${CMAKE_CFG_INTDIR}
+                  -sv ${POLLY_TEST_EXTRA_ARGS}
+                  ${CMAKE_CURRENT_BINARY_DIR}/Unit
+                  DEPENDS PollyUnitTests
+                  COMMENT "Running Polly unit tests")
+      set_target_properties(check-polly-unittests PROPERTIES FOLDER "Polly")
+    endif ()
   endif()
 
 else (NOT DEFINED LLVM_MAIN_SRC_DIR)
 
   set(LLVM_LIT ${LLVM_TOOLS_BINARY_DIR}/llvm-lit)
   set(POLLY_TEST_DEPS llvm-config opt LLVMPolly FileCheck not)
+  if (POLLY_GTEST_AVAIL)
+    list(APPEND POLLY_TEST_DEPS PollyUnitTests)
+  endif ()
 
   set(LLVM_BINARY_DIR "${LLVM_BINARY_DIR}")
   set(LLVM_TOOLS_DIR "${LLVM_TOOLS_BINARY_DIR}")
@@ -89,14 +112,31 @@
     ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.in
     ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg)
 
+  # Run regression and unit tests
   add_lit_testsuite(check-polly "Running polly regression tests"
     ${CMAKE_CURRENT_BINARY_DIR}
     PARAMS polly_site_config=${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg
+           polly_unit_site_config=${CMAKE_CURRENT_BINARY_DIR}/Unit/lit.site.cfg
     DEPENDS ${POLLY_TEST_DEPS}
     )
 
   set_target_properties(check-polly PROPERTIES FOLDER "Polly")
 
+  if (POLLY_GTEST_AVAIL)
+    configure_lit_site_cfg(
+      ${CMAKE_CURRENT_SOURCE_DIR}/Unit/lit.site.cfg.in
+      ${CMAKE_CURRENT_BINARY_DIR}/Unit/lit.site.cfg
+    )
+
+    # Run only unit tests
+    add_lit_testsuite(check-polly-unittests "Running polly unit tests only"
+      ${CMAKE_CURRENT_BINARY_DIR}/Unit
+      PARAMS polly_site_config=${CMAKE_CURRENT_BINARY_DIR}/Unit/lit.site.cfg
+      DEPENDS PollyUnitTests
+      )
+    set_target_properties(check-polly-unittests PROPERTIES FOLDER "Polly")
+  endif ()
+
   # Run polly-check-format as part of polly-check only if we are compiling with
   # clang, so clang-format is availbale.
   # if (TARGET clang-format) would be preferable, but this target is only added
Index: polly/trunk/test/Unit/lit.cfg
===================================================================
--- polly/trunk/test/Unit/lit.cfg
+++ polly/trunk/test/Unit/lit.cfg
@@ -0,0 +1,108 @@
+# -*- Python -*-
+
+# Configuration file for the 'lit' test runner.
+
+import os
+import platform
+
+import lit.formats
+import lit.util
+
+# name: The name of this test suite.
+config.name = 'Polly-Unit'
+
+# suffixes: A list of file extensions to treat as test files.
+config.suffixes = []
+
+# test_source_root: The root path where tests are located.
+# test_exec_root: The root path where tests should be run.
+polly_obj_root = getattr(config, 'polly_obj_root', None)
+if polly_obj_root is not None:
+    config.test_exec_root = os.path.join(polly_obj_root, 'unittests')
+    config.test_source_root = config.test_exec_root
+
+# testFormat: The test format to use to interpret tests.
+llvm_build_mode = getattr(config, 'llvm_build_mode', "Debug")
+config.test_format = lit.formats.GoogleTest(llvm_build_mode, 'Tests')
+
+# Propagate the temp directory. Windows requires this because it uses \Windows\
+# if none of these are present.
+if 'TMP' in os.environ:
+    config.environment['TMP'] = os.environ['TMP']
+if 'TEMP' in os.environ:
+    config.environment['TEMP'] = os.environ['TEMP']
+
+# Propagate path to symbolizer for ASan/MSan.
+for symbolizer in ['ASAN_SYMBOLIZER_PATH', 'MSAN_SYMBOLIZER_PATH']:
+    if symbolizer in os.environ:
+        config.environment[symbolizer] = os.environ[symbolizer]
+
+###
+
+# Check that the object root is known.
+if config.test_exec_root is None:
+    # Otherwise, we haven't loaded the site specific configuration (the user is
+    # probably trying to run on a test file directly, and either the site
+    # configuration hasn't been created by the build system, or we are in an
+    # out-of-tree build situation).
+
+    # Check for 'polly_unit_site_config' user parameter, and use that if available.
+    site_cfg = lit_config.params.get('polly_unit_site_config', None)
+    if site_cfg and os.path.exists(site_cfg):
+        lit_config.load_config(config, site_cfg)
+        raise SystemExit
+
+    # Try to detect the situation where we are using an out-of-tree build by
+    # looking for 'llvm-config'.
+    #
+    # FIXME: I debated (i.e., wrote and threw away) adding logic to
+    # automagically generate the lit.site.cfg if we are in some kind of fresh
+    # build situation. This means knowing how to invoke the build system
+    # though, and I decided it was too much magic.
+
+    llvm_config = lit.util.which('llvm-config', config.environment['PATH'])
+    if not llvm_config:
+        lit_config.fatal('No site specific configuration available!')
+
+    # Get the source and object roots.
+    llvm_src_root = lit.util.capture(['llvm-config', '--src-root']).strip()
+    llvm_obj_root = lit.util.capture(['llvm-config', '--obj-root']).strip()
+    polly_src_root = os.path.join(llvm_src_root, "tools", "polly")
+    polly_obj_root = os.path.join(llvm_obj_root, "tools", "polly")
+
+    # Validate that we got a tree which points to here, using the standard
+    # tools/clang layout.
+    this_src_root = os.path.join(os.path.dirname(__file__),'..','..')
+    if os.path.realpath(polly_src_root) != os.path.realpath(this_src_root):
+        lit_config.fatal('No site specific configuration available!')
+
+    # Check that the site specific configuration exists.
+    site_cfg = os.path.join(polly_obj_root, 'test', 'Unit', 'lit.site.cfg')
+    if not os.path.exists(site_cfg):
+        lit_config.fatal('No site specific configuration available!')
+
+    # Okay, that worked. Notify the user of the automagic, and reconfigure.
+    lit_config.note('using out-of-tree build at %r' % polly_obj_root)
+    lit_config.load_config(config, site_cfg)
+    raise SystemExit
+
+shlibpath_var = ''
+if platform.system() == 'Linux':
+    shlibpath_var = 'LD_LIBRARY_PATH'
+elif platform.system() == 'Darwin':
+    shlibpath_var = 'DYLD_LIBRARY_PATH'
+elif platform.system() == 'Windows':
+    shlibpath_var = 'PATH'
+
+# Point the dynamic loader at dynamic libraries in 'lib'.
+llvm_libs_dir = getattr(config, 'llvm_libs_dir', None)
+if not llvm_libs_dir:
+    lit_config.fatal('No LLVM libs dir set!')
+shlibpath = os.path.pathsep.join((llvm_libs_dir,
+                                 config.environment.get(shlibpath_var,'')))
+
+# Win32 seeks DLLs along %PATH%.
+if sys.platform in ['win32', 'cygwin'] and os.path.isdir(config.shlibdir):
+    shlibpath = os.path.pathsep.join((config.shlibdir, shlibpath))
+
+config.environment[shlibpath_var] = shlibpath
Index: polly/trunk/test/Unit/lit.site.cfg.in
===================================================================
--- polly/trunk/test/Unit/lit.site.cfg.in
+++ polly/trunk/test/Unit/lit.site.cfg.in
@@ -0,0 +1,31 @@
+@LIT_SITE_CFG_IN_HEADER@
+
+import sys
+
+config.llvm_src_root = "@LLVM_SOURCE_DIR@"
+config.llvm_obj_root = "@LLVM_BINARY_DIR@"
+config.llvm_tools_dir = "@LLVM_TOOLS_DIR@"
+config.llvm_libs_dir = "@LLVM_LIBS_DIR@"
+config.llvm_build_mode = "@LLVM_BUILD_MODE@"
+config.polly_obj_root = "@POLLY_BINARY_DIR@"
+config.polly_lib_dir = "@POLLY_LIB_DIR@"
+config.enable_shared = @ENABLE_SHARED@
+config.shlibdir = "@SHLIBDIR@"
+config.target_triple = "@TARGET_TRIPLE@"
+config.enable_gpgpu_codegen = "@GPU_CODEGEN@"
+config.link_polly_into_tools = "@LINK_POLLY_INTO_TOOLS@"
+
+# Support substitution of the tools_dir, libs_dirs, and build_mode with user
+# parameters. This is used when we can't determine the tool dir at
+# configuration time.
+try:
+    config.llvm_tools_dir = config.llvm_tools_dir % lit_config.params
+    config.llvm_libs_dir = config.llvm_libs_dir % lit_config.params
+    config.llvm_build_mode = config.llvm_build_mode % lit_config.params
+except KeyError:
+    e = sys.exc_info()[1]
+    key, = e.args
+    lit_config.fatal("unable to find %r parameter, use '--param=%s=VALUE'" % (key,key))
+
+# Let the main config do the real work.
+lit_config.load_config(config, "@POLLY_SOURCE_DIR@/test/Unit/lit.cfg")
Index: polly/trunk/unittests/CMakeLists.txt
===================================================================
--- polly/trunk/unittests/CMakeLists.txt
+++ polly/trunk/unittests/CMakeLists.txt
@@ -0,0 +1,22 @@
+add_custom_target(PollyUnitTests)
+set_target_properties(PollyUnitTests PROPERTIES FOLDER "Polly")
+
+# add_polly_unittest(test_dirname file1.cpp file2.cpp)
+#
+# Will compile the list of files together and link against Polly and its dependences.
+function(add_polly_unittest test_name)
+  if(COMMAND add_unittest)
+    add_unittest(PollyUnitTests ${test_name} ${ARGN})
+  else()
+    add_executable(${test_name} ${ARGN})
+    set_target_properties(${test_name} PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+
+    target_link_libraries(${test_name} gtest_main gtest)
+    add_dependencies(PollyUnitTests ${test_name})
+
+    set_property(TARGET ${test_name} PROPERTY FOLDER "Polly")
+  endif()
+  target_link_libraries(${test_name} Polly LLVMCore LLVMSupport)
+endfunction()
+
+add_subdirectory(Isl)
Index: polly/trunk/unittests/Isl/CMakeLists.txt
===================================================================
--- polly/trunk/unittests/Isl/CMakeLists.txt
+++ polly/trunk/unittests/Isl/CMakeLists.txt
@@ -0,0 +1,3 @@
+add_polly_unittest(IslTests
+  IslTest.cpp
+  )
Index: polly/trunk/unittests/Isl/IslTest.cpp
===================================================================
--- polly/trunk/unittests/Isl/IslTest.cpp
+++ polly/trunk/unittests/Isl/IslTest.cpp
@@ -0,0 +1,101 @@
+//===- IslTest.cpp ----------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "polly/Support/GICHelper.h"
+#include "gtest/gtest.h"
+#include "isl/val.h"
+
+using namespace llvm;
+using namespace polly;
+
+namespace {
+
+TEST(Isl, APIntToIslVal) {
+  isl_ctx *IslCtx = isl_ctx_alloc();
+
+  {
+    APInt APNOne(32, -1, true);
+    auto *IslNOne = isl_valFromAPInt(IslCtx, APNOne, true);
+    EXPECT_EQ(isl_bool_true, isl_val_is_negone(IslNOne));
+    isl_val_free(IslNOne);
+  }
+
+  {
+    APInt APZero(32, 0, false);
+    auto *IslZero = isl_valFromAPInt(IslCtx, APZero, false);
+    EXPECT_EQ(isl_val_is_zero(IslZero), isl_bool_true);
+    isl_val_free(IslZero);
+  }
+
+  {
+    APInt APOne(32, 1, false);
+    auto *IslOne = isl_valFromAPInt(IslCtx, APOne, false);
+    EXPECT_EQ(isl_val_is_one(IslOne), isl_bool_true);
+    isl_val_free(IslOne);
+  }
+
+  {
+    APInt APTwo(32, 2, false);
+    auto *IslTwo = isl_valFromAPInt(IslCtx, APTwo, false);
+    EXPECT_EQ(isl_val_cmp_si(IslTwo, 2), 0);
+    isl_val_free(IslTwo);
+  }
+
+  {
+    APInt APNOne(32, (1ull << 32) - 1, false);
+    auto *IslNOne = isl_valFromAPInt(IslCtx, APNOne, false);
+    auto *IslRef = isl_val_int_from_ui(IslCtx, (1ull << 32) - 1);
+    EXPECT_EQ(isl_val_eq(IslNOne, IslRef), isl_bool_true);
+    isl_val_free(IslNOne);
+    isl_val_free(IslRef);
+  }
+
+  isl_ctx_free(IslCtx);
+}
+
+TEST(Isl, IslValToAPInt) {
+  isl_ctx *IslCtx = isl_ctx_alloc();
+
+  {
+    auto *IslNOne = isl_val_int_from_si(IslCtx, -1);
+    auto APNOne = APIntFromVal(IslNOne);
+    // APInt has no sign bit, so never equals to a negative number.
+    // FIXME: The canonical representation of a negative APInt is two's
+    // complement.
+    EXPECT_EQ(APNOne, 1);
+  }
+
+  {
+    auto *IslZero = isl_val_int_from_ui(IslCtx, 0);
+    auto APZero = APIntFromVal(IslZero);
+    EXPECT_EQ(APZero, 0);
+  }
+
+  {
+    auto *IslOne = isl_val_int_from_ui(IslCtx, 1);
+    auto APOne = APIntFromVal(IslOne);
+    EXPECT_EQ(APOne, 1);
+  }
+
+  {
+    auto *IslTwo = isl_val_int_from_ui(IslCtx, 2);
+    auto APTwo = APIntFromVal(IslTwo);
+    EXPECT_EQ(APTwo, 2);
+  }
+
+  {
+    auto *IslNOne = isl_val_int_from_ui(IslCtx, (1ull << 32) - 1);
+    auto APNOne = APIntFromVal(IslNOne);
+    EXPECT_EQ(APNOne, (1ull << 32) - 1);
+  }
+
+  isl_ctx_free(IslCtx);
+}
+
+} // anonymous namespace