allow specific test for make check

Makefile.standalone

 # The following variables will likely need to be modified, depending on where
 # and how you built LLVM & Clang. They can be overridden in a command-line
 # invocation of make, like:
 #
 #   make LLVM_SRC_PATH=<path> LIBCXX_INSTALL_PATH=<path> CLANG_PATH=<path> \
 #        PNACL_BIN_PATH=<path> ...
 #
 
 # LLVM_SRC_PATH is the path to the root of the checked out source code. This
 # directory should contain the configure script, the include/ and lib/
@@ skipping 15 matching lines @@
 # tools like qemu.
 TOOLCHAIN_ROOT ?= $(shell readlink -e $(NACL_ROOT)/toolchain/linux_x86)
 
 # PNACL_TOOLCHAIN_ROOT is the location of the PNaCl toolchain.
 # This is used as the default root for finding binutils, libcxx, etc.
 PNACL_TOOLCHAIN_ROOT ?= $(shell readlink -e $(TOOLCHAIN_ROOT)/pnacl_newlib_raw)
 
 # The location of PNaCl tools (e.g., binutils objdump, pnacl-clang++, etc.).
 PNACL_BIN_PATH ?= $(shell readlink -e $(PNACL_TOOLCHAIN_ROOT)/bin)
 
+# Allow tests_lit to be overidden
+TESTS_LIT ?= tests_lit

[Jim Stichnoth, 2016/01/15 19:20:58]

Currently lit is used two situations:

1. "make check-lit" where you may want to run just one test to make it easier to
sift through the error spewage.

2. "make check-xtest" where you may want to run just one test because it takes
several minutes to run them all.

So I think two variables may be in order here.

CHECK_LIT_TESTS ?= tests_lit
CHECK_XTEST_TESTS ?= crosstest/Output

and then make a similar modification to the check-xtest lit command.

It would also be good to document the ?= assignment here with an example of a
single-test override, because I know I for one will continually revisit this
Makefile to remember how it's done.

+
 # Hack to auto-detect autoconf versus cmake build of LLVM.  If the LLVM tools
 # were dynamically linked with something like libLLVM-3.7svn.so, it is an
 # autoconf build, otherwise it is a cmake build.  AUTOCONF is set to 0 for
 # cmake, nonzero for autoconf.
 AUTOCONF ?= $(shell ldd $(PNACL_BIN_PATH)/opt | grep -c libLLVM-)
 
 # CLANG_PATH is the location of the clang compiler to use for building
 # the host binaries.
 CLANG_PATH ?= $(shell readlink -e \
   $(NACL_ROOT)/../third_party/llvm-build/Release+Asserts/bin)
@@ skipping 362 matching lines @@
 # Use runtime.is.built so that build-runtime.py is invoked only once
 # even in a parallel build.
 .INTERMEDIATE: runtime.is.built
 $(RT_OBJ): runtime.is.built
 runtime.is.built: $(RT_SRC) pydir/build-runtime.py
         @echo ================ Building Subzero runtime ================
         ./pydir/build-runtime.py -v --pnacl-root $(PNACL_TOOLCHAIN_ROOT)
 
 check-lit: $(OBJDIR)/pnacl-sz make_symlink
         PNACL_BIN_PATH=$(PNACL_BIN_PATH) \
-        $(LLVM_SRC_PATH)/utils/lit/lit.py -sv tests_lit \
+        $(LLVM_SRC_PATH)/utils/lit/lit.py -sv $(TESTS_LIT) \
             $(FORCEASM_LIT_TEST_EXCLUDES) $(FORCEASM_LIT_PARAM)
 
 ifdef MINIMAL
 check-xtest: $(OBJDIR)/pnacl-sz make_symlink runtime
         @echo "Crosstests disabled, minimal build"
 else
 check-xtest: $(OBJDIR)/pnacl-sz make_symlink runtime
        # Do all native/sse2 tests, but only test_vector_ops for native/sse4.1.
        # For (slow) sandboxed tests, limit to Om1/sse4.1.
         ./pydir/crosstest_generator.py -v --lit \
@@ skipping 111 matching lines @@
         @echo See Subzero size breakdown in bloat/pnacl-sz.bloat.html
 
 docs:
         make -C docs -f Makefile.standalone
 
 clean:
         rm -rf pnacl-sz *.o $(OBJDIR) $(SB_OBJDIR) build/pnacl-sz.bloat.json
 
 clean-all: clean
         rm -rf build/  crosstest/Output/