llvm-project/flang/runtime/CMakeLists.txt

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#===-- runtime/CMakeLists.txt ----------------------------------------------===#
#
# 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
#
#===------------------------------------------------------------------------===#
include(CheckCXXSymbolExists)
include(CheckCXXSourceCompiles)
check_cxx_symbol_exists(strerror string.h HAVE_STRERROR)
check_cxx_symbol_exists(strerror_r string.h HAVE_STRERROR_R)
# Can't use symbol exists here as the function is overloaded in C++
check_cxx_source_compiles(
"#include <string.h>
int main() {
char buf[4096];
return strerror_s(buf, 4096, 0);
}
"
HAVE_DECL_STRERROR_S)
if (NOT (HAVE_STRERROR OR HAVE_STRERROR_R OR HAVE_DECL_STRERROR_S))
message(FATAL_ERROR "None of strerror, strerror_r, strerror_s found.")
endif()
configure_file(config.h.cmake config.h)
# include_directories is used here instead of target_include_directories
# because add_flang_library creates multiple objects (STATIC/SHARED, OBJECT)
# with different names
include_directories(AFTER ${CMAKE_CURRENT_BINARY_DIR})
[flang][driver] Add support for generating executables This patch adds 2 missing items required for `flang-new` to be able to generate executables: 1. The Fortran_main runtime library, which implements the main entry point into Fortran's `PROGRAM` in Flang, 2. Extra linker flags to include Fortran runtime libraries (e.g. Fortran_main). Fortran_main is the bridge between object files generated by Flang and the C runtime that takes care of program set-up at system-level. For every Fortran `PROGRAM`, Flang generates the `_QQmain` function. Fortran_main implements the C `main` function that simply calls `_QQmain`. Additionally, "<driver-path>/../lib" directory is added to the list of search directories for libraries. This is where the required runtime libraries are currently located. Note that this the case for the build directory. We haven't considered installation directories/targets yet. With this change, you can generate an executable that will print `hello, world!` as follows: ```bash $ cat hello.f95 PROGRAM HELLO write(*, *) "hello, world!" END PROGRAM HELLO $ flang-new -flang-experimental-exec hello.f95 ./a.out hello, world! ``` NOTE 1: Fortran_main has to be a static library at all times. It invokes `_QQmain`, which is the main entry point generated by Flang for the given input file (you can check this with `flang-new -S hello.f95 -o - | grep "Qmain"`). This means that Fortran_main has an unresolved dependency at build time. The linker will allow this for a static library. However, if Fortran_main was a shared object, then the linker will produce an error: `undefined symbol: `_QQmain`. NOTE 2: When Fortran runtime libraries are generated as shared libraries (excluding Fortran_main, which is always static), you will need to tell the dynamic linker (by e.g. tweaking LD_LIBRARY_PATH) where to look for them when invoking the executables. For example: ```bash LD_LIBRARY_PATH=$LD_LIBRARY_PATH:<flang-build-dir>/lib/ ./a.out ``` NOTE 3: This feature is considered experimental and currently guarded with a flag: `-flang-experimental-exec`. Differential Revision: https://reviews.llvm.org/D122008 [1] https://github.com/flang-compiler/f18-llvm-project CREDITS: Fortran_main was originally written by Eric Schweitz, Jean Perier, Peter Klausler and Steve Scalpone in the fir-dev` branch in [1]. Co-authored-by: Eric Schweitz <eschweitz@nvidia.com> Co-authored-by: Peter Klausler <pklausler@nvidia.com> Co-authored-by: Jean Perier <jperier@nvidia.com> Co-authored-by: Steve Scalpone <sscalpone@nvidia.com
2022-03-18 00:24:54 +08:00
add_subdirectory(FortranMain)
add_flang_library(FortranRuntime
ISO_Fortran_binding.cpp
allocatable.cpp
assign.cpp
buffer.cpp
command.cpp
complex-reduction.c
copy.cpp
character.cpp
connection.cpp
derived.cpp
derived-api.cpp
descriptor.cpp
descriptor-io.cpp
dot-product.cpp
edit-input.cpp
edit-output.cpp
environment.cpp
extensions.cpp
extrema.cpp
file.cpp
findloc.cpp
format.cpp
inquiry.cpp
internal-unit.cpp
iostat.cpp
io-api.cpp
io-error.cpp
io-stmt.cpp
main.cpp
matmul.cpp
memory.cpp
misc-intrinsic.cpp
namelist.cpp
numeric.cpp
ragged.cpp
random.cpp
reduction.cpp
pointer.cpp
product.cpp
stat.cpp
stop.cpp
sum.cpp
support.cpp
terminator.cpp
time-intrinsic.cpp
tools.cpp
transformational.cpp
type-code.cpp
type-info.cpp
unit.cpp
unit-map.cpp
utf.cpp
LINK_LIBS
FortranDecimal
)