Use lit's internal shell runner on Windows for Clang tests

The behavior can be overridden by setting LIT_USE_INTERNAL_SHELL=0 in
the environment.

This fixes issues with /dev/null for me and brings the test suite time
down to 30s.  =D

llvm-svn: 179283

1 files changed, 12 insertions, 3 deletions

diff --git a/clang/test/lit.cfg b/clang/test/lit.cfg
index 4466f0fc074..e8b39575646 100644
--- a/clang/test/lit.cfg
+++ b/clang/test/lit.cfg
@@ -24,12 +24,21 @@ if platform.system() == 'Windows':
                                      config.environment['PATH']))
         config.environment['PATH'] = path
 
+# Choose between lit's internal shell pipeline runner and a real shell.  If
+# LIT_USE_INTERNAL_SHELL is in the environment, we use that as an override.
+use_lit_shell = os.environ.get("LIT_USE_INTERNAL_SHELL")
+if use_lit_shell:
+    # 0 is external, "" is default, and everything else is internal.
+    execute_external = (use_lit_shell == "0")
+else:
+    # Otherwise we default to internal on Windows and external elsewhere, as
+    # bash on Windows is usually very slow.
+    execute_external = (not sys.platform in ['win32'])
+
 # testFormat: The test format to use to interpret tests.
 #
 # For now we require '&&' between commands, until they get globally killed and
 # the test runner updated.
-execute_external = (platform.system() != 'Windows'
-                    or lit.getBashPath() not in [None, ""])
 config.test_format = lit.formats.ShTest(execute_external)
 
 # suffixes: A list of file extensions to treat as test files.
@@ -219,7 +228,7 @@ if platform.system() not in ['FreeBSD']:
     config.available_features.add('crash-recovery')
 
 # Shell execution
-if platform.system() not in ['Windows'] or lit.getBashPath() != '':
+if execute_external:
     config.available_features.add('shell')
 
 # Exclude MSYS due to transforming '/' to 'X:/mingwroot/'.