The first commit of two importing the gfortran test suite into the repo.

This *does not* contain the test files themselves. Those will be added in a
future commit.

This only contains the cmake files needed to build and the tests, the license
files that govern the tests themselves and changes to the existing
infrastructure. A README and other documentation has been provided.

Some highlights:

  - The tests have only been enabled on non-Windows, non-Apple, x86 and Aarch64
    platforms.

  - The gfortran tests are largely divided into "compile" tests that exercise
    specific behaviors of the compiler such as error messages and the ability
    to adhere to the standard, and "execute" tests that test the end-to-end
    behavior of the compiler and the correctness of the resulting binary.
    In this patch, only the "execute" tests are enabled.

  - A number of the tests have been disabled because they either trigger a
    "not yet implemented" assertion in flang, they cause flang to crash for
    a different reason (due to bugs/unimplemented features not guarded by an
    unimplemented assertion), they use non-standard extensions not (currently)
    supported by flang, or if they fail at runtime (likely because of bugs
    in the compiler or flang runtime, or because of unimplemented features in
    the runtime).

  - The test files themselves will be governed by GPL. The files committed in
    this patch will be governed by the LLVM license.

Differential Revision: https://reviews.llvm.org/D146485

Author: tarunprabhu

Fortran/CMakeLists.txt

@@ -8,3 +8,12 @@
 # directory
 add_subdirectory(UnitTests)
 add_subdirectory(SNAP)
+
+# The gfortran subdirectory contains tests imported as-is from gfortran's
+# test suite. These have not been widely tested, so they are only enabled for
+# certain combinations of platforms and architectures.
+if (NOT WIN32 AND NOT APPLE)
+  if (ARCH MATCHES "x86" OR ARCH MATCHES "AArch64")
+    add_subdirectory(gfortran)
+  endif()
+endif()

Fortran/gfortran/CMakeLists.txt

@@ -0,0 +1,300 @@
+cmake_minimum_required(VERSION 3.24.0)
+
+include(CheckFortranCompilerFlag)
+
+# NOTE: flang does not currently (as of 2023/03/20) support the -w flag. If
+# support for the flag is added, this should be removed.
+remove_definitions(-w)
+
+# If the test suite was configured by adding -flang-experimental-exec, remove
+# that flag from the default compilation flags. It is only needed at link-time
+# anyway, and for that it is explicitly added to those targets that need it.
+#
+# NOTE: This should be removed once the -flang-experimental-exec flag is no
+# longer needed.
+string(REPLACE "-flang-experimental-exec" "" TMP_FFLAGS "${CMAKE_Fortran_FLAGS}")
+set(CMAKE_Fortran_FLAGS "${TMP_FFLAGS}")
+
+# This option is added because as of 2023/03/20, several tests in this
+# directory have been disabled. Some of them exercise unsupported non-standard
+# extensions, others trigger a "not yet implemented" assertion while some cause
+# flang to crash. This option forces all the tests to build and can be used to
+# determine if any of the disabled tests can be enabled.
+option(TEST_SUITE_FORTRAN_FORCE_ALL_TESTS
+  "Build and run all gfortran tests, including those in the 'unsupported', 'unimplemented', 'skipped', and 'failing' categories."
+  OFF)
+
+# Since the FORCE_ALL_TESTS option is a bit too blunt, there are some other
+# options to force building some subsets of the disabled tests.
+
+# The 'unsupported' tests exercise non-standard extensions that are not
+# currently supported. But there is a chance some may be in the future, in which
+# case, it may be worthwhile seeing if any can be removed from the list and
+# enabled permanently.
+option(TEST_SUITE_FORTRAN_FORCE_UNSUPPORTED_TESTS
+  "Build and run all 'unsupported' gfortran tests. These usually test non-standard extensions."
+  OFF)
+
+# The 'unimplemented' tests trigger a "not yet implemented" assertion at
+# compile-time. If those features are implemented, enabling those tests may help
+# in identifying those that can be removed from the list and permanently enabled
+# because the root cause has been addressed.
+option(TEST_SUITE_FORTRAN_FORCE_UNIMPLEMENTED_TESTS
+  "Build and run all 'unimplemented' gfortran tests. These are tests that fail at build-time because of unimplemented features in flang."
+  OFF)
+
+# The 'skipped' tests cause flang to crash at compile-time for "non-obvious"
+# reasons. They could be related to unimplemented features, or they could be
+# bugs in the compiler. In any case, enabling them may help identify those tests
+# that can be removed from the list and permanently enabled because the root
+# cause has been addressed.
+option(TEST_SUITE_FORTRAN_FORCE_SKIPPED_TESTS
+  "Build and run all 'skipped' gfortran tests. These are tests that cause flang to crash."
+  OFF)
+
+# The 'failing' tests fail to pass either because of a bug somewhere in the
+# compiler or the runtime. Enabling these tests may help identify those tests
+# that can be removed from the list and permanently enabled because the root
+# cause has been addressed.
+option(TEST_SUITE_FORTRAN_FORCE_FAILING_TESTS
+  "Build and run all 'failing' tests. These tests failed at runtime, perhaps due to bugs in the code generator or bugs/unimplemented features in the runtime."
+  OFF)
+
+# The ISO_Fortran_binding.h file is required to run some of the tests. This
+# header is copied to ${CMAKE_INSTALL_PREFIX}/include/flang at flang install
+# time which can be found automatically. If the compiler being tested here is
+# not installed, that file will not be found. In that case, the path to it must
+# be provided explicitly.
+set(TEST_SUITE_FORTRAN_ISO_C_HEADER_DIR "" CACHE STRING
+  "Path to the directory containing ISO_Fortran_bindings.h header file.")
+
+# The following cause errors if they are passed to flang via FFLAGS
+set(FLANG_ERRORING_FFLAGS
+  -fallow-invalid-boz
+  -fdec
+  -fdec-format-defaults
+  -fdec-static
+  -fdec-structure
+  # Not sure if the -fdefault-* options will be supported. Maybe in a different
+  # form in which case, this will have to be modified to accommodate those.
+  -fdefault-real-10
+  -fdefault-real-16
+  -fdump-ipa-cp-details
+  -fdump-ipa-fnsummary-details
+  -fdump-ipa-inline-details
+  -fdump-rtl-expand
+  -fdump-tree-all
+  -fdump-tree-cunroll-details
+  -fdump-tree-cunrolli-details
+  -fdump-tree-fre1
+  -fdump-tree-gimple
+  -fdump-tree-ifcvt
+  -fdump-tree-lversion-details
+  -fdump-tree-omplower
+  -fdump-tree-optimized
+  -fdump-tree-original
+  -fdump-tree-pcom-details
+  -fdump-tree-pre-details
+  -fdump-tree-profile-estimate
+  -fdump-tree-reassoc1
+  -fdump-tree-vect-details
+  -ff2c
+  -finline-matmul-limit=0
+  -finline-matmul-limit=10
+  -finline-matmul-limit=100
+  -finline-matmul-limit=1000
+  -finline-matmul-limit=2
+  -finline-matmul-limit=30
+  -fipa-cp
+  -fipa-cp-clone
+  -fipa-pta
+  -fipa-reference
+  -fno-dec
+  -fno-guess-branch-probability
+  -fno-ipa-cp
+  -fno-ipa-modref
+  -fno-ipa-sra
+  -fno-pad-source
+  -fno-tree-ccp
+  -fno-tree-forwprop
+  -fno-tree-fre
+  -fno-tree-loop-optimize
+  -fno-tree-loop-vectorize
+  -fpad-source
+  -fset-g77-defaults
+  -ftest-forall-temp
+  -ftree-loop-distribution
+  -ftree-loop-vectorize
+  -ftree-pre
+  -ftree-slp-vectorize
+  -ftree-tail-merge
+  -ftree-vectorize
+  -ftree-vrp
+  -mdejagnu-cpu=power4
+  # -Os might eventually be supported, so this might also need to be removed
+  # at some point
+  -Og
+  -Os
+  # At some point, if we ever support explicit standard flags, some of these
+  # should be removed.
+  -std=gnu
+  -std=legacy
+  -std=f95
+  -std=f2003
+  -std=f2008
+  -std=f2008ts
+  # At the time of writing, -W warnings are not supported. flang errors out
+  # saying that only -Werror is supported.
+  -Wall
+  -Wampersand
+  -Wanalyzer-too-complex
+  -Warray-bounds
+  -Warray-temporaries
+  -Wconversion
+  -Wconversion-extra
+  -Werner
+  -Werror
+  -Wextra
+  -Wfunction-elimination
+  -Wimplicit-procedure
+  -Wintrinsic-shadow
+  -Wintrinsics-std
+  -Wline-truncation
+  -Wno-all
+  -Wno-analyzer-null-dereference
+  -Wno-analyzer-possible-null-dereference
+  -Wno-analyzer-too-complex
+  -Wno-analyzer-use-of-uninitialized-value
+  -Wno-c-binding-type
+  -Wno-complain-wrong-lang
+  -Wno-error
+  -Wno-intrinsic-shadow
+  -Wno-intrinsics-std
+  -Wno-lto-type-mismatch
+  -Wno-tabs
+  -Wno-underflow
+  -Wrealloc-lhs
+  -Wrealloc-lhs-all
+  -Wreturn-type
+  -Wstringop-overflow
+  -Wsurprising
+  -Wtabs
+  -Wuninitialized
+  -Wunused
+  -Wunused-dummy-argument
+  -Wunused-function
+  -Wunused-parameter
+  -Wunused-variable
+  -Wzerotrip
+)
+
+set(HEADER_SEARCH_PATH "${TEST_SUITE_FORTRAN_ISO_C_HEADER_DIR}")
+if (NOT HEADER_SEARCH_PATH)
+  get_filename_component(Fortran_BINDIR ${CMAKE_Fortran_COMPILER} DIRECTORY)
+  get_filename_component(Fortran_PREFIX ${Fortran_BINDIR} DIRECTORY)
+
+  set(HEADER_SEARCH_PATH "${Fortran_PREFIX}/include/flang")
+endif()
+
+find_file(ISO_FORTRAN_C_HEADER
+  ISO_Fortran_binding.h
+  PATHS ${HEADER_SEARCH_PATH}
+  REQUIRED)
+
+get_filename_component(ISO_FORTRAN_C_HEADER_DIR
+  "${ISO_FORTRAN_C_HEADER}"
+  DIRECTORY)
+
+# This pulls out options in dg-options into `${Variable}`
+function(gfortran_dg_options_fflags Variable File)
+  # Some files have dg-options which we need to pick up. These should be in
+  # the first line but often aren't.
+  #
+  # We also need to be careful not to pick up target-specific dg-options.
+  set(DG_FFLAGS)
+
+  file(STRINGS ${File} FileLines)
+  foreach(FileLine ${FileLines})
+    # Looking for `dg-options "..."` or `dg-additional-options "..."` without
+    # `{ target` afterwards (ignoring spaces).
+    if(FileLine MATCHES "dg-(additional-)?options [{]?[ ]*\"([^\"]*)\"[ ]*[}]?(.*)")
+      # This is needed to turn the string into a list of FFLAGS
+      separate_arguments(FILE_FFLAGS UNIX_COMMAND ${CMAKE_MATCH_2})
+      # This does the negative lookahead for `{ target` anywhere in the rest of
+      # the line
+      if(NOT "${CMAKE_MATCH_3}" MATCHES "{ +target")
+        list(APPEND DG_FFLAGS ${FILE_FFLAGS})
+      endif()
+    endif()
+  endforeach()
+
+  # Remove any flags that will cause flang to raise an error.
+  if (DG_FFLAGS)
+    list(REMOVE_ITEM DG_FFLAGS ${FLANG_ERRORING_FFLAGS})
+  endif()
+
+  # Set the parent scope variable
+  set(${Variable} ${DG_FFLAGS} PARENT_SCOPE)
+endfunction()
+
+function(gfortran_execute_test File)
+  cmake_parse_arguments(GFORTRAN "" "PREFIX" "FFLAGS;LDFLAGS;DEPFILES" ${ARGN})
+  # There are a few tests with duplicate filenames, and CMake wants all target
+  # names to be unique, so we add a disambiguator to the target name. The
+  # disambiguator uses the path of the file relative to the top-level directory
+  # containing all the tests from the gfortran test suite.
+
+  # The ${File} argument is guaranteed to be the absolute path to the source
+  # file.
+  string(REPLACE "${PROJECT_SOURCE_DIR}/Fortran/gfortran/" "" Name "${File}")
+
+  # Replace any '/' separators with 2 underscores. Just replacing it by a single
+  # underscore results in conflicts. For instance, there is a conflict between
+  # regression/coarray_ptr_comp_2.f08 and regression/coarray/ptr_comp_2.f08
+  # which are unrelated tests. Other such conflicts are probably also unrelated.
+  string(REPLACE "/" "__" Name "${Name}")
+
+  # Retain the extension of the source file in the final target name because
+  # there are cases where two source files with the same basename but different
+  # extensions and they, too, represent completely different and unrelated
+  # tests.
+  string(REPLACE "." "_" Name "${Name}")
+
+  set(_target "${GFORTRAN_PREFIX}-${Name}")
+
+  gfortran_dg_options_fflags(DG_FFLAGS ${File})
+
+  # Add any flags that were requested
+  list(APPEND FFLAGS ${DG_FFLAGS} ${GFORTRAN_FFLAGS})
+  list(APPEND LDFLAGS ${GFORTRAN_LDFLAGS})
+
+  llvm_test_executable_no_test(${_target} ${File} ${GFORTRAN_DEPFILES})
+  llvm_test_run()
+
+  llvm_add_test_for_target(${_target})
+  target_include_directories(${_target} PRIVATE ${ISO_FORTRAN_C_HEADER_DIR})
+
+  # This is a workaround because cmake does not currently recognize the .f03
+  # and .f08 extensions. A patch to fix cmake has been accepted and the fix
+  # should be available in CMake 3.27. It might be better to check the CMake
+  # CMake version and do this conditionally.
+  list(APPEND SOURCES ${File})
+  list(APPEND SOURCES ${GFORTRAN_DEPFILES})
+  foreach(Source ${SOURCES})
+    get_filename_component(Ext ${Source} LAST_EXT)
+    if("${Ext}" STREQUAL ".f03" OR
+        "${Ext}" STREQUAL ".F03" OR
+        "${Ext}" STREQUAL ".f08" OR
+        "${Ext}" STREQUAL ".F08")
+      set_source_files_properties(${Source} PROPERTIES LANGUAGE Fortran)
+    endif()
+  endforeach()
+
+  # NOTE: This should be removed when the -flang-experimental-exec flag is no
+  # longer needed.
+  target_link_options(${_target} PRIVATE -flang-experimental-exec)
+  set_target_properties(${_target} PROPERTIES LINKER_LANGUAGE Fortran)
+endfunction()
+
+add_subdirectory(regression)
+add_subdirectory(torture)