[Flang][Test] Add support to change the default target triple for tests

In this patch I added support to change the default target triple used
by flang tests using the cmake variable: FLANG_TEST_TARGET_TRIPLE.

This functionality is implemented using the LLVM_TARGET_TRIPLE_ENV
variable, so that must be defined as well.

An example use:
`-DLLVM_TARGET_TRIPLE_ENV="LLVM_TARGET_TRIPLE_ENV" -DFLANG_TEST_TARGET_TRIPLE="aarch64-linux-gnu"`

Differential revision: https://reviews.llvm.org/D138530

Change-Id: I38e4a46a65109d415a9b72c8a0bf8a955e937280

flang/README.md

@@ -109,6 +109,12 @@ cmake \
 ninja
 ```
 
+By default flang tests that do not specify an explicit `--target` flag use
+LLVM's default target triple. For these tests, if there is a need to test on a
+different triple by overriding the default, the following needs to be added to
+the cmake command above:
+`-DLLVM_TARGET_TRIPLE_ENV="<some string>" -DFLANG_TEST_TARGET_TRIPLE="<your triple>"`.
+
 To run the flang tests on this build, execute the command in the "build"
 directory:
 ```bash

flang/test/CMakeLists.txt

@@ -100,3 +100,11 @@ else()
     PARAMS ${FLANG_TEST_PARAMS}
     DEPENDS ${FLANG_TEST_DEPENDS})
 endif()
+
+# To modify the default target triple for flang tests.
+if (DEFINED FLANG_TEST_TARGET_TRIPLE)
+  if (NOT DEFINED LLVM_TARGET_TRIPLE_ENV OR LLVM_TARGET_TRIPLE_ENV STREQUAL "")
+    message(FATAL_ERROR "LLVM_TARGET_TRIPLE_ENV must also be defined in order "
+                        "to use FLANG_TEST_TARGET_TRIPLE.")
+  endif()
+endif()

flang/test/Unit/lit.cfg.py

@@ -30,3 +30,8 @@ config.environment['LD_LIBRARY_PATH'] = path
 
 # Propagate PYTHON_EXECUTABLE into the environment
 #config.environment['PYTHON_EXECUTABLE'] = sys.executable
+
+# To modify the default target triple for flang tests.
+if config.flang_test_triple:
+    config.target_triple = config.flang_test_triple
+    config.environment[config.llvm_target_triple_env] = config.flang_test_triple

flang/test/Unit/lit.site.cfg.py.in

@@ -2,6 +2,7 @@
 
 config.llvm_src_root = "@LLVM_SOURCE_DIR@"
 config.llvm_obj_root = "@LLVM_BINARY_DIR@"
+config.llvm_target_triple_env = "@LLVM_TARGET_TRIPLE_ENV@"
 config.llvm_tools_dir = lit_config.substitute("@LLVM_TOOLS_DIR@")
 config.llvm_libs_dir = lit_config.substitute("@LLVM_LIBS_DIR@")
 config.llvm_build_mode = lit_config.substitute("@LLVM_BUILD_MODE@")
@@ -9,6 +10,7 @@ config.lit_tools_dir = "@LLVM_LIT_TOOLS_DIR@"
 config.flang_obj_root = "@FLANG_BINARY_DIR@"
 config.flang_src_root = "@FLANG_SOURCE_DIR@"
 config.flang_libs_dir = "@LLVM_LIBRARY_OUTPUT_INTDIR@"
+config.flang_test_triple = "@FLANG_TEST_TARGET_TRIPLE@"
 config.flang_tools_dir = "@LLVM_RUNTIME_OUTPUT_INTDIR@"
 config.target_triple = "@LLVM_TARGET_TRIPLE@"
 config.python_executable = "@Python3_EXECUTABLE@"

flang/test/lit.cfg.py

@@ -45,6 +45,11 @@ config.targets = frozenset(config.targets_to_build.split())
 for arch in config.targets_to_build.split():
     config.available_features.add(arch.lower() + '-registered-target')
 
+# To modify the default target triple for flang tests.
+if config.flang_test_triple:
+    config.target_triple = config.flang_test_triple
+    config.environment[config.llvm_target_triple_env] = config.flang_test_triple
+
 # excludes: A list of directories to exclude from the testsuite. The 'Inputs'
 # subdirectories contain auxiliary inputs for various tests in their parent
 # directories.

flang/test/lit.site.cfg.py.in

@@ -5,6 +5,7 @@ import sys
 config.llvm_tools_dir = lit_config.substitute("@LLVM_TOOLS_DIR@")
 config.llvm_shlib_dir = lit_config.substitute(path(r"@SHLIBDIR@"))
 config.llvm_plugin_ext = "@LLVM_PLUGIN_EXT@"
+config.llvm_target_triple_env = "@LLVM_TARGET_TRIPLE_ENV@"
 config.lit_tools_dir = "@LLVM_LIT_TOOLS_DIR@"
 config.errc_messages = "@LLVM_LIT_ERRC_MESSAGES@"
 config.flang_obj_root = "@FLANG_BINARY_DIR@"
@@ -13,6 +14,7 @@ config.flang_tools_dir = lit_config.substitute("@FLANG_TOOLS_DIR@")
 config.flang_intrinsic_modules_dir = "@FLANG_INTRINSIC_MODULES_DIR@"
 config.flang_llvm_tools_dir = "@CMAKE_BINARY_DIR@/bin"
 config.flang_lib_dir = "@CMAKE_BINARY_DIR@/lib"
+config.flang_test_triple = "@FLANG_TEST_TARGET_TRIPLE@"
 config.flang_examples = @FLANG_BUILD_EXAMPLES@
 config.python_executable = "@PYTHON_EXECUTABLE@"
 config.flang_standalone_build = @FLANG_STANDALONE_BUILD@