Un-revert "Teach the CMake build system to run lit's test suite. These can be run"

Summary:
Depends on https://reviews.llvm.org/D35879.

This reverts rL257268, which in turn was a revert of rL257221.
https://reviews.llvm.org/D35879 marks the tests in the lit test suite
that fail on Windows as XFAIL, which should allow these tests to pass
on Windows-based buildbots.

Reviewers: delcypher, beanz, mgorny, jroelofs, rnk

Reviewed By: mgorny

Subscribers: rnk, ddunbar, george.karpenkov, llvm-commits

Differential Revision: https://reviews.llvm.org/D35880

llvm-svn: 309310

3 files changed, 50 insertions, 2 deletions

diff --git a/llvm/utils/lit/CMakeLists.txt b/llvm/utils/lit/CMakeLists.txt
new file mode 100644
index 00000000000..709e16bda5b
--- /dev/null
+++ b/llvm/utils/lit/CMakeLists.txt
@@ -0,0 +1,26 @@
+# The configured file is not placed in the correct location
+# until the tests are run as we need to copy it into
+# a copy of the tests folder
+configure_file("tests/lit.site.cfg.in" "lit.site.cfg" @ONLY)
+
+# Lit's test suite creates output files next to the sources which makes the
+# source tree dirty. This is undesirable because we do out of source builds.
+# To work around this the tests and the configuration file are copied into the
+# build directory just before running them. The tests are not copied over at
+# configure time (i.e. `file(COPY ...)`) because this could lead to stale
+# tests being run.
+add_custom_target(prepare-check-lit
+  COMMAND ${CMAKE_COMMAND} -E copy_directory "${CMAKE_CURRENT_SOURCE_DIR}/tests" "${CMAKE_CURRENT_BINARY_DIR}/tests"
+  COMMAND ${CMAKE_COMMAND} -E copy "${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg" "${CMAKE_CURRENT_BINARY_DIR}/tests"
+  COMMENT "Preparing lit tests"
+)
+
+# Add rules for lit's own test suite
+add_lit_testsuite(check-lit "Running lit's tests"
+  ${CMAKE_CURRENT_BINARY_DIR}
+  DEPENDS "FileCheck" "not" "prepare-check-lit"
+)
+
+# For IDEs
+set_target_properties(check-lit PROPERTIES FOLDER "Tests")
+set_target_properties(prepare-check-lit PROPERTIES FOLDER "Tests")
diff --git a/llvm/utils/lit/tests/lit.cfg b/llvm/utils/lit/tests/lit.cfg
index ed1c6c68d0c..0c98299285a 100644
--- a/llvm/utils/lit/tests/lit.cfg
+++ b/llvm/utils/lit/tests/lit.cfg
@@ -26,12 +26,20 @@ config.test_exec_root = config.test_source_root
 config.target_triple = '(unused)'
 
 src_root = os.path.join(config.test_source_root, '..')
-config.environment['PYTHONPATH'] = src_root
+llvm_src_root = getattr(config, 'llvm_src_root', None)
+if llvm_src_root != None:
+  # ``src_root`` may be in LLVM's binary build directory which does not contain
+  # ``lit.py``, so use `llvm_src_root` instead.
+  lit_path = os.path.join(llvm_src_root, 'utils', 'lit')
+else:
+  lit_path = src_root
+
+config.environment['PYTHONPATH'] = lit_path # Required because some tests import the lit module
 config.substitutions.append(('%{src_root}', src_root))
 config.substitutions.append(('%{inputs}', os.path.join(
             src_root, 'tests', 'Inputs')))
 config.substitutions.append(('%{lit}', "%%{python} %s" % (
-            os.path.join(src_root, 'lit.py'),)))
+            os.path.join(lit_path, 'lit.py'),)))
 config.substitutions.append(('%{python}', sys.executable))
 
 # Enable coverage.py reporting, assuming the coverage module has been installed
@@ -55,3 +63,9 @@ except ImportError:
 
 if sys.platform.startswith('win') or sys.platform.startswith('cygwin'):
     config.available_features.add('windows')
+
+# Add llvm tools directory if this config is being loaded indirectly
+llvm_tools_dir = getattr(config, 'llvm_tools_dir', None)
+if llvm_tools_dir != None:
+    path = os.path.pathsep.join((llvm_tools_dir, config.environment['PATH']))
+    config.environment['PATH'] = path
diff --git a/llvm/utils/lit/tests/lit.site.cfg.in b/llvm/utils/lit/tests/lit.site.cfg.in
new file mode 100644
index 00000000000..bdc1f58575e
--- /dev/null
+++ b/llvm/utils/lit/tests/lit.site.cfg.in
@@ -0,0 +1,8 @@
+## Autogenerated by LLVM/Clang configuration.
+# Do not edit!
+config.llvm_src_root = "@LLVM_SOURCE_DIR@"
+config.llvm_obj_root = "@LLVM_BINARY_DIR@"
+config.llvm_tools_dir = "@LLVM_TOOLS_BINARY_DIR@"
+
+# Let the main config do the real work.
+lit_config.load_config(config, "@LLVM_BINARY_DIR@/utils/lit/tests/lit.cfg")