tools/f18/flang-to-external-fc.in - llvm-project/flang - Git at Google

 #! /usr/bin/env bash
 #===-- tools/f18/flang-to-external-fc.sh --------------------------*- sh -*-===#
 #
 # Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #
 #===------------------------------------------------------------------------===#
 # A wrapper script for Flang's compiler driver that was developed for testing and
 # experimenting. You should be able to use it as a regular compiler driver. It
 # will:
 #   * run Flang's compiler driver to unparse the input source files
 #   * use the external compiler (defined via FLANG_FC environment variable) to
 #   compile the unparsed source files
 #
 # Tested with Bash 4.4. This script will exit immediately if you use an
 # older version of Bash.
 #===------------------------------------------------------------------------===#
 set -euo pipefail

 # Global variables to make the parsing of input arguments a bit easier
 INPUT_FILES=()
 OPTIONS=()
 OUTPUT_FILE=""
 MODULE_DIR=""
 INTRINSICS_MOD_DIR=""
 COMPILE_ONLY="False"
 PREPROCESS_ONLY="False"
 PRINT_VERSION="False"

 # === check_bash_version ======================================================
 #
 # Checks the Bash version that's used to run this script. Exits immediately
 # with a non-zero return code if it's lower than 4.4. Otherwise returns 0
 # (success).
 # =============================================================================
 check_bash_version() {
   message="Error: Your Bash is too old. Please use Bash >= 4.4"
   # Major version
   [[ "${BASH_VERSINFO[0]:-0}" -lt 4 ]] && echo $message && exit 1

   # Minor version
   if [[ "${BASH_VERSINFO[0]}" == 4 ]]; then
     [[ "${BASH_VERSINFO[1]:-0}" -lt 4 ]] && echo $message && exit 1
   fi

   return 0
 }

 # === parse_args ==============================================================
 #
 # Parse the input arguments passed to this script. Sets the global variables
 # declared at the top.
 #
 # INPUTS:
 #   $1 - all input arguments
 # OUTPUTS:
 #  Saved in the global variables for this script
 # =============================================================================
 parse_args()
 {
   while [ "${1:-}" != "" ]; do
       # CASE 1: Compiler option
       if [[ "${1:0:1}" == "-" ]] ; then
         # Output file - extract it into a global variable
         if [[ "$1" == "-o" ]] ; then
           shift
           OUTPUT_FILE="$1"
           shift
           continue
         fi

         # Module directory - extract it into a global variable
         if [[ "$1" == "-module-dir" ]]; then
           shift
           MODULE_DIR="$1"
           shift
           continue
         fi

         # Intrinsics module dir - extract it into a global var
         if [[ "$1" == "-intrinsics-module-directory" ]]; then shift
           INTRINSICS_MOD_DIR=$1
           shift
           continue
         fi

         # Module suffix cannot be modified - this script defines it before
         # calling the driver.
         if [[ "$1" == "-module-suffix" ]]; then
           echo "ERROR: \'-module-suffix\' is not available when using the \'flang\' script"
           exit 1
         fi

         # Special treatment for `J <dir>` and `-I <dir>`. We translate these
         # into `J<dir>` and `-I<dir>` respectively.
         if [[ "$1" == "-J" ]] || [[ "$1" == "-I" ]]; then
           opt=$1
           shift
           OPTIONS+=("$opt$1")
           shift
           continue
         fi

         # This is a regular option - just add it to the list.
         OPTIONS+=($1)
         if [[ $1 == "-c" ]]; then
           COMPILE_ONLY="True"
         fi

         if [[ $1 == "-E" ]]; then
           PREPROCESS_ONLY="True"
         fi

         if [[ $1 == "-v" || $1 == "--version" ]]; then
           PRINT_VERSION="True"
         fi

         shift
         continue

       # CASE 2: A regular file (either source or a library file)
       elif [[ -f "$1" ]]; then
         INPUT_FILES+=($1)
         shift
         continue

       else
         # CASE 3: Unsupported
         echo "ERROR: unrecognised option format: \`$1\`. Perhaps non-existent file?"
         exit 1
       fi
   done
 }

 # === categorise_files ========================================================
 #
 # Categorises input files into:
 #   * Fortran source files (to be compiled)
 #   * library files (to be linked into the final executable)
 #
 # INPUTS:
 #   $1 - all input files to be categorised (array, name reference)
 # OUTPUTS:
 #   $2 - Fortran source files extracted from $1 (array, name reference)
 #   $3 - other source files extracted from $1 (array, name reference)
 #   $4 - object files extracted from $1 (array, name reference)
 #   $5 - lib files extracted from $1 (array, name reference)
 # =============================================================================
 categorise_files()
 {
   local -n -r all_files=$1
   local -n fortran_sources=$2
   local -n other_sources=$3
   local -n objects=$4
   local -n libs=$5

   for current_file in "${all_files[@]}"; do
     file_ext=${current_file##*.}
     if [[ $file_ext == "f" ]] || [[ $file_ext == "f90" ]] ||
        [[ $file_ext == "f" ]] || [[ $file_ext == "F" ]] || [[ $file_ext == "ff" ]] ||
        [[ $file_ext == "f90" ]] || [[ $file_ext == "F90" ]] || [[ $file_ext == "ff90" ]] ||
        [[ $file_ext == "f95" ]] || [[ $file_ext == "F95" ]] || [[ $file_ext == "ff95" ]] ||
        [[ $file_ext == "cuf" ]] || [[ $file_ext == "CUF" ]] || [[ $file_ext == "f18" ]] ||
        [[ $file_ext == "F18" ]] || [[ $file_ext == "ff18" ]]; then
       fortran_sources+=($current_file)
     elif [[ $file_ext == "a" ]] || [[ $file_ext == "so" ]]; then
       libs+=($current_file)
     elif [[ $file_ext == "o" ]]; then
       objects+=($current_file)
     else
       other_sources+=($current_file)
     fi
   done
 }

 # === categorise_opts ==========================================================
 #
 # Categorises compiler options into options for:
 #   * the Flang driver (either new or the "throwaway" driver)
 #   * the external Fortran driver that will generate the code
 # Most options accepted by Flang will be claimed by it. The only exceptions are
 # `-I` and `-J`.
 #
 # INPUTS:
 #   $1 - all compiler options (array, name reference)
 # OUTPUTS:
 #   $2 - compiler options for the Flang driver (array, name reference)
 #   $3 - compiler options for the external driver (array, name reference)
 # =============================================================================
 categorise_opts()
 {
   local -n all_opts=$1
   local -n flang_opts=$2
   local -n fc_opts=$3

   for opt in "${all_opts[@]}"; do
     # These options are claimed by Flang, but should've been dealt with in parse_args.
     if  [[ $opt == "-module-dir" ]] ||
       [[ $opt == "-o" ]] ||
       [[ $opt == "-fintrinsic-modules-path" ]] ; then
       echo "ERROR: $opt should've been fully processed by \`parse_args\`"
       exit 1
     fi

     if
       # The options claimed by Flang. This list needs to be compatible with
       # what's supported by Flang's compiler driver (i.e. `flang-new`).
       [[ $opt == "-cpp" ]] ||
       [[ $opt =~ ^-D.* ]] ||
       [[ $opt == "-E" ]] ||
       [[ $opt == "-falternative-parameter-statement" ]] ||
       [[ $opt == "-fbackslash" ]] ||
       [[ $opt == "-fcolor-diagnostics" ]] ||
       [[ $opt == "-fdefault-double-8" ]] ||
       [[ $opt == "-fdefault-integer-8" ]] ||
       [[ $opt == "-fdefault-real-8" ]] ||
       [[ $opt == "-ffixed-form" ]] ||
       [[ $opt =~ ^-ffixed-line-length=.* ]] ||
       [[ $opt == "-ffree-form" ]] ||
       [[ $opt == "-fimplicit-none" ]] ||
       [[ $opt =~ ^-finput-charset=.* ]] ||
       [[ $opt == "-flarge-sizes" ]] ||
       [[ $opt == "-flogical-abbreviations" ]] ||
       [[ $opt == "-fno-color-diagnostics" ]] ||
       [[ $opt == "-fxor-operator" ]] ||
       [[ $opt == "-help" ]] ||
       [[ $opt == "-nocpp" ]] ||
       [[ $opt == "-pedantic" ]] ||
       [[ $opt =~ ^-std=.* ]] ||
       [[ $opt =~ ^-U.* ]] ||
       [[ $opt == "-Werror" ]]; then
       flang_opts+=($opt)
     elif
       # We translate the following into equivalents understood by `flang-new`
       [[ $opt == "-Mfixed" ]] || [[ $opt == "-Mfree" ]]; then
         case $opt in
           -Mfixed)
             flang_opts+=("-ffixed-form")
           ;;

           -Mfree)
             flang_opts+=("-ffree-form")
           ;;

         *)
           echo "ERROR: $opt has no equivalent in 'flang-new'"
           exit 1
           ;;
       esac
     elif
       # Options that are needed for both Flang and the external driver.
       [[ $opt =~ -I.* ]] ||
       [[ $opt =~ -J.* ]] ||
       [[ $opt == "-fopenmp" ]] ||
       [[ $opt == "-fopenacc" ]]; then
       flang_opts+=($opt)
       fc_opts+=($opt)
     else
       # All other options are claimed for the external driver.
       fc_opts+=($opt)
     fi
   done
 }

 # === get_external_fc_name ====================================================
 #
 # Returns the name of external Fortran compiler based on values of
 # environment variables.
 # =============================================================================
 get_external_fc_name() {
   if [[ -v FLANG_FC ]]; then
     echo ${FLANG_FC}
   elif [[ -v F18_FC ]]; then
     # We support F18_FC for backwards compatibility.
     echo ${F18_FC}
   else
     echo gfortran
   fi
 }

 # === preprocess ==============================================================
 #
 # Runs the preprocessing. Fortran files are preprocessed using Flang. Other
 # files are preprocessed using the external Fortran compiler.
 #
 # INPUTS:
 #   $1 - Fortran source files (array, name reference)
 #   $2 - other source files (array, name reference)
 #   $3 - compiler flags (array, name reference)
 # =============================================================================
 preprocess() {
   local -n fortran_srcs=$1
   local -n other_srcs=$2
   local -n opts=$3

   local ext_fc="$(get_external_fc_name)"

   local -r wd=$(cd "$(dirname "$0")/.." && pwd)

   # Use the provided output file name.
   if [[ ! -z ${OUTPUT_FILE:+x} ]]; then
     output_definition="-o $OUTPUT_FILE"
   fi

   # Preprocess fortran sources using Flang
   for idx in "${!fortran_srcs[@]}"; do
     if ! "$wd/bin/flang-new" -E "${opts[@]}" "${fortran_srcs[$idx]}" ${output_definition:+$output_definition}
     then status=$?
          echo flang: in "$PWD", flang-new failed with exit status $status: "$wd/bin/flang-new" "${opts[@]}" "$@" >&2
          exit $status
     fi
   done

   # Preprocess other sources using Flang
   for idx in "${!other_srcs[@]}"; do
     if ! $ext_fc -E "${opts[@]}" "${other_srcs[$idx]}" ${output_definition:+$output_definition}
     then status=$?
          echo flang: in "$PWD", flang-new failed with exit status $status: "$wd/bin/flang-new" "${opts[@]}" "$@" >&2
          exit $status
     fi
   done
 }

 # === get_relocatable_name ======================================================
 # This method generates the name of the output file for the compilation phase
 # (triggered with `-c`). If the user of this script is only interested in
 # compilation (`flang -c`), use $OUTPUT_FILE provided that it was defined.
 # Otherwise, use the usual heuristics:
 #   * file.f --> file.o
 #   * file.c --> file.o
 #
 # INPUTS:
 #   $1 - input source file for which to generate the output name
 # =============================================================================
 get_relocatable_name() {
   local -r src_file=$1

   if [[ $COMPILE_ONLY == "True" ]] && [[ ! -z ${OUTPUT_FILE:+x} ]]; then
     out_file="$OUTPUT_FILE"
   else
     current_ext=${src_file##*.}
     new_ext="o"

     out_file=$(basename "${src_file}" "$current_ext")${new_ext}
   fi

   echo "$out_file"
 }

 # === main ====================================================================
 # Main entry point for this script
 # =============================================================================
 main() {
   check_bash_version
   parse_args "$@"

   if [[ $PRINT_VERSION == "True" ]]; then
     echo "flang version @FLANG_VERSION@"
     exit 0
   fi

   # Source, object and library files provided by the user
   local fortran_source_files=()
   local other_source_files=()
   local object_files=()
   local lib_files=()
   categorise_files INPUT_FILES fortran_source_files other_source_files object_files lib_files

   if [[ $PREPROCESS_ONLY == "True" ]]; then
     preprocess fortran_source_files other_source_files OPTIONS
     exit 0
   fi

   # Options for the Flang driver.
   # NOTE: We need `-fc1` to make sure that the frontend driver rather than
   # compiler driver is used. We also need to make sure that that's the first
   # flag that the driver will see (otherwise it assumes compiler/toolchain
   # driver mode).
   local flang_options=("-fc1")
   # Options for the external Fortran Compiler
   local ext_fc_options=()
   categorise_opts OPTIONS flang_options ext_fc_options

   local -r wd=$(cd "$(dirname "$0")/.." && pwd)

   # uuidgen is common but not installed by default on some distros
   if ! command -v uuidgen &> /dev/null
   then
     echo "uuidgen is required for generating unparsed file names."
     exit 1
   fi

   # STEP 1: Unparse
   # Base-name for the unparsed files. These are just temporary files that are
   # first generated and then deleted by this script.
   # NOTE: We need to make sure that the base-name is unique to every
   # invocation. Otherwise we can't use this script in parallel.
   local -r unique_id=$(uuidgen | cut -b25-36)
   local -r unparsed_file_base="flang_unparsed_file_$unique_id"

   flang_options+=("-module-suffix")
   flang_options+=(".f18.mod")
   flang_options+=("-fdebug-unparse")
   flang_options+=("-fno-analyzed-objects-for-unparse")

   [[ ! -z ${MODULE_DIR} ]] && flang_options+=("-module-dir ${MODULE_DIR}")
   [[ ! -z ${INTRINSICS_MOD_DIR} ]] && flang_options+=("-intrinsics-module-directory ${INTRINSICS_MOD_DIR}")
   for idx in "${!fortran_source_files[@]}"; do
     set +e
     "$wd/bin/flang-new" "${flang_options[@]}" "${fortran_source_files[$idx]}" -o "${unparsed_file_base}_${idx}.f90"
     ret_status=$?
     set -e
     if [[ $ret_status != 0 ]]; then
          echo flang: in "$PWD", flang-new failed with exit status "$ret_status": "$wd/bin/flang-new" "${flang_options[@]}" "$@" >&2
          exit "$ret_status"
     fi
   done

   # STEP 2: Compile Fortran Source Files
   local ext_fc="$(get_external_fc_name)"
   # Temporary object files generated by this script. To be deleted at the end.
   local temp_object_files=()
   for idx in "${!fortran_source_files[@]}"; do
     # We always have to specify the output name with `-o <out_obj_file>`. This
     # is because we are using the unparsed rather than the original source file
     # below. As a result, we cannot rely on the compiler-generated output name.
     out_obj_file=$(get_relocatable_name "${fortran_source_files[$idx]}")

     set +e
     $ext_fc "-c" "${ext_fc_options[@]}" "${unparsed_file_base}_${idx}.f90" "-o" "${out_obj_file}"
     ret_status=$?
     set -e
     if [[ $ret_status != 0 ]]; then
       echo flang: in "$PWD", "$ext_fc" failed with exit status "$ret_status": "$ext_fc" "${ext_fc_options[@]}" "$@" >&2
          exit "$ret_status"
     fi
     temp_object_files+=(${out_obj_file})
   done

   # Delete the unparsed files
   for idx in "${!fortran_source_files[@]}"; do
     rm "${unparsed_file_base}_${idx}.f90"
   done

   # STEP 3: Compile Other Source Files
   for idx in "${!other_source_files[@]}"; do
     # We always specify the output name with `-o <out_obj_file>`. The user
     # might have used `-o`, but we never add it to $OPTIONS (or
     # $ext_fc_options). Hence we need to use `get_relocatable_name`.
     out_obj_file=$(get_relocatable_name "${other_source_files[$idx]}")

     set +e
     $ext_fc "-c" "${ext_fc_options[@]}" "${other_source_files[${idx}]}" "-o" "${out_obj_file}"
     ret_status=$?
     set -e
     if [[ $ret_status != 0 ]]; then
       echo flang: in "$PWD", "$ext_fc" failed with exit status "$ret_status": "$ext_fc" "${ext_fc_options[@]}" "$@" >&2
          exit "$ret_status"
     fi
     temp_object_files+=(${out_obj_file})
   done

   # STEP 4: Link
   if [[ $COMPILE_ONLY == "True" ]]; then
     exit 0;
   fi

   if [[ ${#temp_object_files[@]} -ge 1 ]] || [[ ${#object_files[@]} -ge 1 ]] ; then
     # If $OUTPUT_FILE was specified, use it for the output name.
     if [[ ! -z ${OUTPUT_FILE:+x} ]]; then
       output_definition="-o $OUTPUT_FILE"
     else
       output_definition=""
     fi

     set +e
     $ext_fc "${ext_fc_options[@]}" "${object_files[@]}" "${temp_object_files[@]}" "${lib_files[@]}" ${output_definition:+$output_definition}
     ret_status=$?
     set -e
     if [[ $ret_status != 0 ]]; then
          echo flang: in "$PWD", "$ext_fc" failed with exit status "$ret_status": "$ext_fc" "${ext_fc_options[@]}" "$@" >&2
          exit "$ret_status"
     fi
   fi

   # Delete intermediate object files
   for idx in "${!fortran_source_files[@]}"; do
     rm "${temp_object_files[$idx]}"
   done
 }

 main "${@}"
	#! /usr/bin/env bash
	#===-- tools/f18/flang-to-external-fc.sh --------------------------- sh --===#
	#
	# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	# See https://llvm.org/LICENSE.txt for license information.
	# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	#
	#===------------------------------------------------------------------------===#
	# A wrapper script for Flang's compiler driver that was developed for testing and
	# experimenting. You should be able to use it as a regular compiler driver. It
	# will:
	# * run Flang's compiler driver to unparse the input source files
	# * use the external compiler (defined via FLANG_FC environment variable) to
	# compile the unparsed source files
	#
	# Tested with Bash 4.4. This script will exit immediately if you use an
	# older version of Bash.
	#===------------------------------------------------------------------------===#
	set -euo pipefail

	# Global variables to make the parsing of input arguments a bit easier
	INPUT_FILES=()
	OPTIONS=()
	OUTPUT_FILE=""
	MODULE_DIR=""
	INTRINSICS_MOD_DIR=""
	COMPILE_ONLY="False"
	PREPROCESS_ONLY="False"
	PRINT_VERSION="False"

	# === check_bash_version ======================================================
	#
	# Checks the Bash version that's used to run this script. Exits immediately
	# with a non-zero return code if it's lower than 4.4. Otherwise returns 0
	# (success).
	# =============================================================================
	check_bash_version() {
	message="Error: Your Bash is too old. Please use Bash >= 4.4"
	# Major version
	[[ "${BASH_VERSINFO[0]:-0}" -lt 4 ]] && echo $message && exit 1

	# Minor version
	if [[ "${BASH_VERSINFO[0]}" == 4 ]]; then
	[[ "${BASH_VERSINFO[1]:-0}" -lt 4 ]] && echo $message && exit 1
	fi

	return 0
	}

	# === parse_args ==============================================================
	#
	# Parse the input arguments passed to this script. Sets the global variables
	# declared at the top.
	#
	# INPUTS:
	# $1 - all input arguments
	# OUTPUTS:
	# Saved in the global variables for this script
	# =============================================================================
	parse_args()
	{
	while [ "${1:-}" != "" ]; do
	# CASE 1: Compiler option
	if [[ "${1:0:1}" == "-" ]] ; then
	# Output file - extract it into a global variable
	if [[ "$1" == "-o" ]] ; then
	shift
	OUTPUT_FILE="$1"
	shift
	continue
	fi

	# Module directory - extract it into a global variable
	if [[ "$1" == "-module-dir" ]]; then
	shift
	MODULE_DIR="$1"
	shift
	continue
	fi

	# Intrinsics module dir - extract it into a global var
	if [[ "$1" == "-intrinsics-module-directory" ]]; then shift
	INTRINSICS_MOD_DIR=$1
	shift
	continue
	fi

	# Module suffix cannot be modified - this script defines it before
	# calling the driver.
	if [[ "$1" == "-module-suffix" ]]; then
	echo "ERROR: \'-module-suffix\' is not available when using the \'flang\' script"
	exit 1
	fi

	# Special treatment for `J <dir>` and `-I <dir>`. We translate these
	# into `J<dir>` and `-I<dir>` respectively.
	if [[ "$1" == "-J" ]] \|\| [[ "$1" == "-I" ]]; then
	opt=$1
	shift
	OPTIONS+=("$opt$1")
	shift
	continue
	fi

	# This is a regular option - just add it to the list.
	OPTIONS+=($1)
	if [[ $1 == "-c" ]]; then
	COMPILE_ONLY="True"
	fi

	if [[ $1 == "-E" ]]; then
	PREPROCESS_ONLY="True"
	fi

	if [[ $1 == "-v" \|\| $1 == "--version" ]]; then
	PRINT_VERSION="True"
	fi

	shift
	continue

	# CASE 2: A regular file (either source or a library file)
	elif [[ -f "$1" ]]; then
	INPUT_FILES+=($1)
	shift
	continue

	else
	# CASE 3: Unsupported
	echo "ERROR: unrecognised option format: \`$1\`. Perhaps non-existent file?"
	exit 1
	fi
	done
	}

	# === categorise_files ========================================================
	#
	# Categorises input files into:
	# * Fortran source files (to be compiled)
	# * library files (to be linked into the final executable)
	#
	# INPUTS:
	# $1 - all input files to be categorised (array, name reference)
	# OUTPUTS:
	# $2 - Fortran source files extracted from $1 (array, name reference)
	# $3 - other source files extracted from $1 (array, name reference)
	# $4 - object files extracted from $1 (array, name reference)
	# $5 - lib files extracted from $1 (array, name reference)
	# =============================================================================
	categorise_files()
	{
	local -n -r all_files=$1
	local -n fortran_sources=$2
	local -n other_sources=$3
	local -n objects=$4
	local -n libs=$5

	for current_file in "${all_files[@]}"; do
	file_ext=${current_file##*.}
	if [[ $file_ext == "f" ]] \|\| [[ $file_ext == "f90" ]] \|\|
	[[ $file_ext == "f" ]] \|\| [[ $file_ext == "F" ]] \|\| [[ $file_ext == "ff" ]] \|\|
	[[ $file_ext == "f90" ]] \|\| [[ $file_ext == "F90" ]] \|\| [[ $file_ext == "ff90" ]] \|\|
	[[ $file_ext == "f95" ]] \|\| [[ $file_ext == "F95" ]] \|\| [[ $file_ext == "ff95" ]] \|\|
	[[ $file_ext == "cuf" ]] \|\| [[ $file_ext == "CUF" ]] \|\| [[ $file_ext == "f18" ]] \|\|
	[[ $file_ext == "F18" ]] \|\| [[ $file_ext == "ff18" ]]; then
	fortran_sources+=($current_file)
	elif [[ $file_ext == "a" ]] \|\| [[ $file_ext == "so" ]]; then
	libs+=($current_file)
	elif [[ $file_ext == "o" ]]; then
	objects+=($current_file)
	else
	other_sources+=($current_file)
	fi
	done
	}

	# === categorise_opts ==========================================================
	#
	# Categorises compiler options into options for:
	# * the Flang driver (either new or the "throwaway" driver)
	# * the external Fortran driver that will generate the code
	# Most options accepted by Flang will be claimed by it. The only exceptions are
	# `-I` and `-J`.
	#
	# INPUTS:
	# $1 - all compiler options (array, name reference)
	# OUTPUTS:
	# $2 - compiler options for the Flang driver (array, name reference)
	# $3 - compiler options for the external driver (array, name reference)
	# =============================================================================
	categorise_opts()
	{
	local -n all_opts=$1
	local -n flang_opts=$2
	local -n fc_opts=$3

	for opt in "${all_opts[@]}"; do
	# These options are claimed by Flang, but should've been dealt with in parse_args.
	if [[ $opt == "-module-dir" ]] \|\|
	[[ $opt == "-o" ]] \|\|
	[[ $opt == "-fintrinsic-modules-path" ]] ; then
	echo "ERROR: $opt should've been fully processed by \`parse_args\`"
	exit 1
	fi

	if
	# The options claimed by Flang. This list needs to be compatible with
	# what's supported by Flang's compiler driver (i.e. `flang-new`).
	[[ $opt == "-cpp" ]] \|\|
	[[ $opt =~ ^-D.* ]] \|\|
	[[ $opt == "-E" ]] \|\|
	[[ $opt == "-falternative-parameter-statement" ]] \|\|
	[[ $opt == "-fbackslash" ]] \|\|
	[[ $opt == "-fcolor-diagnostics" ]] \|\|
	[[ $opt == "-fdefault-double-8" ]] \|\|
	[[ $opt == "-fdefault-integer-8" ]] \|\|
	[[ $opt == "-fdefault-real-8" ]] \|\|
	[[ $opt == "-ffixed-form" ]] \|\|
	[[ $opt =~ ^-ffixed-line-length=.* ]] \|\|
	[[ $opt == "-ffree-form" ]] \|\|
	[[ $opt == "-fimplicit-none" ]] \|\|
	[[ $opt =~ ^-finput-charset=.* ]] \|\|
	[[ $opt == "-flarge-sizes" ]] \|\|
	[[ $opt == "-flogical-abbreviations" ]] \|\|
	[[ $opt == "-fno-color-diagnostics" ]] \|\|
	[[ $opt == "-fxor-operator" ]] \|\|
	[[ $opt == "-help" ]] \|\|
	[[ $opt == "-nocpp" ]] \|\|
	[[ $opt == "-pedantic" ]] \|\|
	[[ $opt =~ ^-std=.* ]] \|\|
	[[ $opt =~ ^-U.* ]] \|\|
	[[ $opt == "-Werror" ]]; then
	flang_opts+=($opt)
	elif
	# We translate the following into equivalents understood by `flang-new`
	[[ $opt == "-Mfixed" ]] \|\| [[ $opt == "-Mfree" ]]; then
	case $opt in
	-Mfixed)
	flang_opts+=("-ffixed-form")
	;;

	-Mfree)
	flang_opts+=("-ffree-form")
	;;

	*)
	echo "ERROR: $opt has no equivalent in 'flang-new'"
	exit 1
	;;
	esac
	elif
	# Options that are needed for both Flang and the external driver.
	[[ $opt =~ -I.* ]] \|\|
	[[ $opt =~ -J.* ]] \|\|
	[[ $opt == "-fopenmp" ]] \|\|
	[[ $opt == "-fopenacc" ]]; then
	flang_opts+=($opt)
	fc_opts+=($opt)
	else
	# All other options are claimed for the external driver.
	fc_opts+=($opt)
	fi
	done
	}

	# === get_external_fc_name ====================================================
	#
	# Returns the name of external Fortran compiler based on values of
	# environment variables.
	# =============================================================================
	get_external_fc_name() {
	if [[ -v FLANG_FC ]]; then
	echo ${FLANG_FC}
	elif [[ -v F18_FC ]]; then
	# We support F18_FC for backwards compatibility.
	echo ${F18_FC}
	else
	echo gfortran
	fi
	}

	# === preprocess ==============================================================
	#
	# Runs the preprocessing. Fortran files are preprocessed using Flang. Other
	# files are preprocessed using the external Fortran compiler.
	#
	# INPUTS:
	# $1 - Fortran source files (array, name reference)
	# $2 - other source files (array, name reference)
	# $3 - compiler flags (array, name reference)
	# =============================================================================
	preprocess() {
	local -n fortran_srcs=$1
	local -n other_srcs=$2
	local -n opts=$3

	local ext_fc="$(get_external_fc_name)"

	local -r wd=$(cd "$(dirname "$0")/.." && pwd)

	# Use the provided output file name.
	if [[ ! -z ${OUTPUT_FILE:+x} ]]; then
	output_definition="-o $OUTPUT_FILE"
	fi

	# Preprocess fortran sources using Flang
	for idx in "${!fortran_srcs[@]}"; do
	if ! "$wd/bin/flang-new" -E "${opts[@]}" "${fortran_srcs[$idx]}" ${output_definition:+$output_definition}
	then status=$?
	echo flang: in "$PWD", flang-new failed with exit status $status: "$wd/bin/flang-new" "${opts[@]}" "$@" >&2
	exit $status
	fi
	done

	# Preprocess other sources using Flang
	for idx in "${!other_srcs[@]}"; do
	if ! $ext_fc -E "${opts[@]}" "${other_srcs[$idx]}" ${output_definition:+$output_definition}
	then status=$?
	echo flang: in "$PWD", flang-new failed with exit status $status: "$wd/bin/flang-new" "${opts[@]}" "$@" >&2
	exit $status
	fi
	done
	}

	# === get_relocatable_name ======================================================
	# This method generates the name of the output file for the compilation phase
	# (triggered with `-c`). If the user of this script is only interested in
	# compilation (`flang -c`), use $OUTPUT_FILE provided that it was defined.
	# Otherwise, use the usual heuristics:
	# * file.f --> file.o
	# * file.c --> file.o
	#
	# INPUTS:
	# $1 - input source file for which to generate the output name
	# =============================================================================
	get_relocatable_name() {
	local -r src_file=$1

	if [[ $COMPILE_ONLY == "True" ]] && [[ ! -z ${OUTPUT_FILE:+x} ]]; then
	out_file="$OUTPUT_FILE"
	else
	current_ext=${src_file##*.}
	new_ext="o"

	out_file=$(basename "${src_file}" "$current_ext")${new_ext}
	fi

	echo "$out_file"
	}

	# === main ====================================================================
	# Main entry point for this script
	# =============================================================================
	main() {
	check_bash_version
	parse_args "$@"

	if [[ $PRINT_VERSION == "True" ]]; then
	echo "flang version @FLANG_VERSION@"
	exit 0
	fi

	# Source, object and library files provided by the user
	local fortran_source_files=()
	local other_source_files=()
	local object_files=()
	local lib_files=()
	categorise_files INPUT_FILES fortran_source_files other_source_files object_files lib_files

	if [[ $PREPROCESS_ONLY == "True" ]]; then
	preprocess fortran_source_files other_source_files OPTIONS
	exit 0
	fi

	# Options for the Flang driver.
	# NOTE: We need `-fc1` to make sure that the frontend driver rather than
	# compiler driver is used. We also need to make sure that that's the first
	# flag that the driver will see (otherwise it assumes compiler/toolchain
	# driver mode).
	local flang_options=("-fc1")
	# Options for the external Fortran Compiler
	local ext_fc_options=()
	categorise_opts OPTIONS flang_options ext_fc_options

	local -r wd=$(cd "$(dirname "$0")/.." && pwd)

	# uuidgen is common but not installed by default on some distros
	if ! command -v uuidgen &> /dev/null
	then
	echo "uuidgen is required for generating unparsed file names."
	exit 1
	fi

	# STEP 1: Unparse
	# Base-name for the unparsed files. These are just temporary files that are
	# first generated and then deleted by this script.
	# NOTE: We need to make sure that the base-name is unique to every
	# invocation. Otherwise we can't use this script in parallel.
	local -r unique_id=$(uuidgen \| cut -b25-36)
	local -r unparsed_file_base="flang_unparsed_file_$unique_id"

	flang_options+=("-module-suffix")
	flang_options+=(".f18.mod")
	flang_options+=("-fdebug-unparse")
	flang_options+=("-fno-analyzed-objects-for-unparse")

	[[ ! -z ${MODULE_DIR} ]] && flang_options+=("-module-dir ${MODULE_DIR}")
	[[ ! -z ${INTRINSICS_MOD_DIR} ]] && flang_options+=("-intrinsics-module-directory ${INTRINSICS_MOD_DIR}")
	for idx in "${!fortran_source_files[@]}"; do
	set +e
	"$wd/bin/flang-new" "${flang_options[@]}" "${fortran_source_files[$idx]}" -o "${unparsed_file_base}_${idx}.f90"
	ret_status=$?
	set -e
	if [[ $ret_status != 0 ]]; then
	echo flang: in "$PWD", flang-new failed with exit status "$ret_status": "$wd/bin/flang-new" "${flang_options[@]}" "$@" >&2
	exit "$ret_status"
	fi
	done

	# STEP 2: Compile Fortran Source Files
	local ext_fc="$(get_external_fc_name)"
	# Temporary object files generated by this script. To be deleted at the end.
	local temp_object_files=()
	for idx in "${!fortran_source_files[@]}"; do
	# We always have to specify the output name with `-o <out_obj_file>`. This
	# is because we are using the unparsed rather than the original source file
	# below. As a result, we cannot rely on the compiler-generated output name.
	out_obj_file=$(get_relocatable_name "${fortran_source_files[$idx]}")

	set +e
	$ext_fc "-c" "${ext_fc_options[@]}" "${unparsed_file_base}_${idx}.f90" "-o" "${out_obj_file}"
	ret_status=$?
	set -e
	if [[ $ret_status != 0 ]]; then
	echo flang: in "$PWD", "$ext_fc" failed with exit status "$ret_status": "$ext_fc" "${ext_fc_options[@]}" "$@" >&2
	exit "$ret_status"
	fi
	temp_object_files+=(${out_obj_file})
	done

	# Delete the unparsed files
	for idx in "${!fortran_source_files[@]}"; do
	rm "${unparsed_file_base}_${idx}.f90"
	done

	# STEP 3: Compile Other Source Files
	for idx in "${!other_source_files[@]}"; do
	# We always specify the output name with `-o <out_obj_file>`. The user
	# might have used `-o`, but we never add it to $OPTIONS (or
	# $ext_fc_options). Hence we need to use `get_relocatable_name`.
	out_obj_file=$(get_relocatable_name "${other_source_files[$idx]}")

	set +e
	$ext_fc "-c" "${ext_fc_options[@]}" "${other_source_files[${idx}]}" "-o" "${out_obj_file}"
	ret_status=$?
	set -e
	if [[ $ret_status != 0 ]]; then
	echo flang: in "$PWD", "$ext_fc" failed with exit status "$ret_status": "$ext_fc" "${ext_fc_options[@]}" "$@" >&2
	exit "$ret_status"
	fi
	temp_object_files+=(${out_obj_file})
	done

	# STEP 4: Link
	if [[ $COMPILE_ONLY == "True" ]]; then
	exit 0;
	fi

	if [[ ${#temp_object_files[@]} -ge 1 ]] \|\| [[ ${#object_files[@]} -ge 1 ]] ; then
	# If $OUTPUT_FILE was specified, use it for the output name.
	if [[ ! -z ${OUTPUT_FILE:+x} ]]; then
	output_definition="-o $OUTPUT_FILE"
	else
	output_definition=""
	fi

	set +e
	$ext_fc "${ext_fc_options[@]}" "${object_files[@]}" "${temp_object_files[@]}" "${lib_files[@]}" ${output_definition:+$output_definition}
	ret_status=$?
	set -e
	if [[ $ret_status != 0 ]]; then
	echo flang: in "$PWD", "$ext_fc" failed with exit status "$ret_status": "$ext_fc" "${ext_fc_options[@]}" "$@" >&2
	exit "$ret_status"
	fi
	fi

	# Delete intermediate object files
	for idx in "${!fortran_source_files[@]}"; do
	rm "${temp_object_files[$idx]}"
	done
	}

	main "${@}"