[flang] Generate main only when a Fortran program statement is present #89938
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@llvm/pr-subscribers-clang @llvm/pr-subscribers-flang-fir-hlfir Author: David Truby (DavidTruby) ChangesThis patch changes the behaviour for flang to only create and link to a This means that flang-new can be used to link even when the program is Patch is 30.69 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/89938.diff 23 Files Affected:
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 922bda721dc780..4b852b297a6b99 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -6582,12 +6582,6 @@ def J : JoinedOrSeparate<["-"], "J">,
Group<gfortran_Group>,
Alias<module_dir>;
-let Visibility = [FlangOption] in {
-def no_fortran_main : Flag<["-"], "fno-fortran-main">,
- Visibility<[FlangOption]>, Group<f_Group>,
- HelpText<"Do not include Fortran_main.a (provided by Flang) when linking">;
-} // let Visibility = [ FlangOption ]
-
//===----------------------------------------------------------------------===//
// FC1 Options
//===----------------------------------------------------------------------===//
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index b65b96db16bd79..fec11c7e716fdf 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1191,118 +1191,10 @@ bool tools::addOpenMPRuntime(const Compilation &C, ArgStringList &CmdArgs,
return true;
}
-/// Determines if --whole-archive is active in the list of arguments.
-static bool isWholeArchivePresent(const ArgList &Args) {
- bool WholeArchiveActive = false;
- for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA)) {
- if (Arg) {
- for (StringRef ArgValue : Arg->getValues()) {
- if (ArgValue == "--whole-archive")
- WholeArchiveActive = true;
- if (ArgValue == "--no-whole-archive")
- WholeArchiveActive = false;
- }
- }
- }
-
- return WholeArchiveActive;
-}
-
-/// Determine if driver is invoked to create a shared object library (-static)
-static bool isSharedLinkage(const ArgList &Args) {
- return Args.hasArg(options::OPT_shared);
-}
-
-/// Determine if driver is invoked to create a static object library (-shared)
-static bool isStaticLinkage(const ArgList &Args) {
- return Args.hasArg(options::OPT_static);
-}
-
-/// Add Fortran runtime libs for MSVC
-static void addFortranRuntimeLibsMSVC(const ArgList &Args,
- llvm::opt::ArgStringList &CmdArgs) {
- unsigned RTOptionID = options::OPT__SLASH_MT;
- if (auto *rtl = Args.getLastArg(options::OPT_fms_runtime_lib_EQ)) {
- RTOptionID = llvm::StringSwitch<unsigned>(rtl->getValue())
- .Case("static", options::OPT__SLASH_MT)
- .Case("static_dbg", options::OPT__SLASH_MTd)
- .Case("dll", options::OPT__SLASH_MD)
- .Case("dll_dbg", options::OPT__SLASH_MDd)
- .Default(options::OPT__SLASH_MT);
- }
- switch (RTOptionID) {
- case options::OPT__SLASH_MT:
- CmdArgs.push_back("/WHOLEARCHIVE:Fortran_main.static.lib");
- break;
- case options::OPT__SLASH_MTd:
- CmdArgs.push_back("/WHOLEARCHIVE:Fortran_main.static_dbg.lib");
- break;
- case options::OPT__SLASH_MD:
- CmdArgs.push_back("/WHOLEARCHIVE:Fortran_main.dynamic.lib");
- break;
- case options::OPT__SLASH_MDd:
- CmdArgs.push_back("/WHOLEARCHIVE:Fortran_main.dynamic_dbg.lib");
- break;
- }
-}
-
-// Add FortranMain runtime lib
-static void addFortranMain(const ToolChain &TC, const ArgList &Args,
- llvm::opt::ArgStringList &CmdArgs) {
- // 0. Shared-library linkage
- // If we are attempting to link a library, we should not add
- // -lFortran_main.a to the link line, as the `main` symbol is not
- // required for a library and should also be provided by one of
- // the translation units of the code that this shared library
- // will be linked against eventually.
- if (isSharedLinkage(Args) || isStaticLinkage(Args)) {
- return;
- }
-
- // 1. MSVC
- if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
- addFortranRuntimeLibsMSVC(Args, CmdArgs);
- return;
- }
-
- // 2. GNU and similar
- const Driver &D = TC.getDriver();
- const char *FortranMainLinkFlag = "-lFortran_main";
-
- // Warn if the user added `-lFortran_main` - this library is an implementation
- // detail of Flang and should be handled automaticaly by the driver.
- for (const char *arg : CmdArgs) {
- if (strncmp(arg, FortranMainLinkFlag, strlen(FortranMainLinkFlag)) == 0)
- D.Diag(diag::warn_drv_deprecated_custom)
- << FortranMainLinkFlag
- << "see the Flang driver documentation for correct usage";
- }
-
- // The --whole-archive option needs to be part of the link line to make
- // sure that the main() function from Fortran_main.a is pulled in by the
- // linker. However, it shouldn't be used if it's already active.
- // TODO: Find an equivalent of `--whole-archive` for Darwin and AIX.
- if (!isWholeArchivePresent(Args) && !TC.getTriple().isMacOSX() &&
- !TC.getTriple().isOSAIX()) {
- CmdArgs.push_back("--whole-archive");
- CmdArgs.push_back(FortranMainLinkFlag);
- CmdArgs.push_back("--no-whole-archive");
- return;
- }
-
- CmdArgs.push_back(FortranMainLinkFlag);
-}
-
/// Add Fortran runtime libs
void tools::addFortranRuntimeLibs(const ToolChain &TC, const ArgList &Args,
llvm::opt::ArgStringList &CmdArgs) {
- // 1. Link FortranMain
- // FortranMain depends on FortranRuntime, so needs to be listed first. If
- // -fno-fortran-main has been passed, skip linking Fortran_main.a
- if (!Args.hasArg(options::OPT_no_fortran_main))
- addFortranMain(TC, Args, CmdArgs);
-
- // 2. Link FortranRuntime and FortranDecimal
+ // Link FortranRuntime and FortranDecimal
// These are handled earlier on Windows by telling the frontend driver to
// add the correct libraries to link against as dependents in the object
// file.
diff --git a/clang/lib/Driver/ToolChains/Flang.cpp b/clang/lib/Driver/ToolChains/Flang.cpp
index 6d93c1f3d7034a..8955b9fb653c2a 100644
--- a/clang/lib/Driver/ToolChains/Flang.cpp
+++ b/clang/lib/Driver/ToolChains/Flang.cpp
@@ -282,7 +282,6 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
assert(TC.getTriple().isKnownWindowsMSVCEnvironment() &&
"can only add VS runtime library on Windows!");
// if -fno-fortran-main has been passed, skip linking Fortran_main.a
- bool LinkFortranMain = !Args.hasArg(options::OPT_no_fortran_main);
if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
CmdArgs.push_back(Args.MakeArgString(
"--dependent-lib=" + TC.getCompilerRTBasename(Args, "builtins")));
@@ -300,8 +299,6 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
case options::OPT__SLASH_MT:
CmdArgs.push_back("-D_MT");
CmdArgs.push_back("--dependent-lib=libcmt");
- if (LinkFortranMain)
- CmdArgs.push_back("--dependent-lib=Fortran_main.static.lib");
CmdArgs.push_back("--dependent-lib=FortranRuntime.static.lib");
CmdArgs.push_back("--dependent-lib=FortranDecimal.static.lib");
break;
@@ -309,8 +306,6 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
CmdArgs.push_back("-D_MT");
CmdArgs.push_back("-D_DEBUG");
CmdArgs.push_back("--dependent-lib=libcmtd");
- if (LinkFortranMain)
- CmdArgs.push_back("--dependent-lib=Fortran_main.static_dbg.lib");
CmdArgs.push_back("--dependent-lib=FortranRuntime.static_dbg.lib");
CmdArgs.push_back("--dependent-lib=FortranDecimal.static_dbg.lib");
break;
@@ -318,8 +313,6 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
CmdArgs.push_back("-D_MT");
CmdArgs.push_back("-D_DLL");
CmdArgs.push_back("--dependent-lib=msvcrt");
- if (LinkFortranMain)
- CmdArgs.push_back("--dependent-lib=Fortran_main.dynamic.lib");
CmdArgs.push_back("--dependent-lib=FortranRuntime.dynamic.lib");
CmdArgs.push_back("--dependent-lib=FortranDecimal.dynamic.lib");
break;
@@ -328,8 +321,6 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
CmdArgs.push_back("-D_DEBUG");
CmdArgs.push_back("-D_DLL");
CmdArgs.push_back("--dependent-lib=msvcrtd");
- if (LinkFortranMain)
- CmdArgs.push_back("--dependent-lib=Fortran_main.dynamic_dbg.lib");
CmdArgs.push_back("--dependent-lib=FortranRuntime.dynamic_dbg.lib");
CmdArgs.push_back("--dependent-lib=FortranDecimal.dynamic_dbg.lib");
break;
diff --git a/flang/docs/FlangDriver.md b/flang/docs/FlangDriver.md
index ac120b4ff09b6d..351595ac0afdb7 100644
--- a/flang/docs/FlangDriver.md
+++ b/flang/docs/FlangDriver.md
@@ -179,46 +179,20 @@ like this:
```
$ flang -v -o example example.o
-"/usr/bin/ld" [...] example.o [...] "--whole-archive" "-lFortran_main"
-"--no-whole-archive" "-lFortranRuntime" "-lFortranDecimal" [...]
+"/usr/bin/ld" [...] example.o [...] "-lFortranRuntime" "-lFortranDecimal" [...]
```
The automatically added libraries are:
-* `Fortran_main`: Provides the main entry point `main` that then invokes
- `_QQmain` with the Fortran program unit. This library has a dependency to
- the `FortranRuntime` library.
* `FortranRuntime`: Provides most of the Flang runtime library.
* `FortranDecimal`: Provides operations for decimal numbers.
-The default is that, when using Flang as the linker, one of the Fortran
-translation units provides the program unit and therefore it is assumed that
-Fortran is the main code part (calling into C/C++ routines via `BIND (C)`
-interfaces). When composing the linker commandline, Flang uses
-`--whole-archive` and `--no-whole-archive` (Windows: `/WHOLEARCHIVE:`,
-Darwin & AIX: *not implemented yet*) to make sure that all for `Fortran_main`
-is processed by the linker. This is done to issue a proper error message when
-multiple definitions of `main` occur. This happens, for instance, when linking
-a code that has a Fortran program unit with a C/C++ code that also defines a
-`main` function. A user may be required to explicitly provide the C++ runtime
-libraries at link time (e.g., via `-lstdc++` for STL)
-
If the code is C/C++ based and invokes Fortran routines, one can either use Clang
or Flang as the linker driver. If Clang is used, it will automatically all
required runtime libraries needed by C++ (e.g., for STL) to the linker invocation.
In this case, one has to explicitly provide the Fortran runtime libraries
-`FortranRuntime` and/or `FortranDecimal`. An alternative is to use Flang to link
-and use the `-fno-fortran-main` flag. This flag removes
-`Fortran_main` from the linker stage and hence requires one of the C/C++
-translation units to provide a definition of the `main` function. In this case,
-it may be required to explicitly supply C++ runtime libraries as mentioned above.
-
-When creating shared or static libraries using Flang with `-shared` or `-static`
-flag, Fortran_main is automatically removed from the linker stage (i.e.,
-`-fno-fortran-main` is on by default). It is assumed that when creating a
-static or shared library, the generated library does not need a `main`
-function, as a final link stage will occur that will provide the `Fortran_main`
-library when creating the final executable.
+`FortranRuntime` and/or `FortranDecimal`. An alternative is to use Flang to link.
+In this case, it may be required to explicitly supply C++ runtime libraries.
On Darwin, the logical root where the system libraries are located (sysroot)
must be specified. This can be done with the CMake build flag `DEFAULT_SYSROOT`
diff --git a/flang/include/flang/Optimizer/Builder/Runtime/EnvironmentDefaults.h b/flang/include/flang/Optimizer/Builder/Runtime/EnvironmentDefaults.h
index 18a24bad396044..216d3bcec137e1 100755
--- a/flang/include/flang/Optimizer/Builder/Runtime/EnvironmentDefaults.h
+++ b/flang/include/flang/Optimizer/Builder/Runtime/EnvironmentDefaults.h
@@ -22,6 +22,7 @@
namespace fir {
class FirOpBuilder;
+class GlobalOp;
} // namespace fir
namespace mlir {
@@ -37,7 +38,7 @@ namespace fir::runtime {
/// Create the list of environment variable defaults for the runtime to set. The
/// form of the generated list is defined in the runtime header file
/// environment-default-list.h
-void genEnvironmentDefaults(
+fir::GlobalOp genEnvironmentDefaults(
fir::FirOpBuilder &builder, mlir::Location loc,
const std::vector<Fortran::lower::EnvironmentDefault> &envDefaults);
diff --git a/flang/include/flang/Optimizer/Builder/Runtime/Main.h b/flang/include/flang/Optimizer/Builder/Runtime/Main.h
new file mode 100644
index 00000000000000..62faf46e1fc778
--- /dev/null
+++ b/flang/include/flang/Optimizer/Builder/Runtime/Main.h
@@ -0,0 +1,28 @@
+//===-- Main.h - generate main runtime API calls ----------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef FORTRAN_OPTIMIZER_BUILDER_RUNTIME_MAIN_H
+#define FORTRAN_OPTIMIZER_BUILDER_RUNTIME_MAIN_H
+
+namespace mlir {
+class Location;
+} // namespace mlir
+
+namespace fir {
+class FirOpBuilder;
+class GlobalOp;
+} // namespace fir
+
+namespace fir::runtime {
+
+void genMain(fir::FirOpBuilder &builder, mlir::Location loc,
+ fir::GlobalOp &env);
+
+}
+
+#endif // FORTRAN_OPTIMIZER_BUILDER_RUNTIME_MAIN_H
diff --git a/flang/lib/Lower/Bridge.cpp b/flang/lib/Lower/Bridge.cpp
index 8b62fe8c022f80..afb5496ff8bc29 100644
--- a/flang/lib/Lower/Bridge.cpp
+++ b/flang/lib/Lower/Bridge.cpp
@@ -36,6 +36,7 @@
#include "flang/Optimizer/Builder/Runtime/Character.h"
#include "flang/Optimizer/Builder/Runtime/Derived.h"
#include "flang/Optimizer/Builder/Runtime/EnvironmentDefaults.h"
+#include "flang/Optimizer/Builder/Runtime/Main.h"
#include "flang/Optimizer/Builder/Runtime/Ragged.h"
#include "flang/Optimizer/Builder/Runtime/Stop.h"
#include "flang/Optimizer/Builder/Todo.h"
@@ -359,8 +360,10 @@ class FirConverter : public Fortran::lower::AbstractConverter {
// not need to be generated even if no defaults are specified.
// However, generating main or changing when the runtime reads
// environment variables is required to do so.
- fir::runtime::genEnvironmentDefaults(*builder, toLocation(),
+ auto env = fir::runtime::genEnvironmentDefaults(*builder, toLocation(),
bridge.getEnvironmentDefaults());
+
+ fir::runtime::genMain(*builder, toLocation(), env);
});
finalizeOpenACCLowering();
diff --git a/flang/lib/Optimizer/Builder/CMakeLists.txt b/flang/lib/Optimizer/Builder/CMakeLists.txt
index 06339b116cd899..95f19ed4dfbdf8 100644
--- a/flang/lib/Optimizer/Builder/CMakeLists.txt
+++ b/flang/lib/Optimizer/Builder/CMakeLists.txt
@@ -24,6 +24,7 @@ add_flang_library(FIRBuilder
Runtime/Inquiry.cpp
Runtime/Intrinsics.cpp
Runtime/Numeric.cpp
+ Runtime/Main.cpp
Runtime/Pointer.cpp
Runtime/Ragged.cpp
Runtime/Reduction.cpp
diff --git a/flang/lib/Optimizer/Builder/Runtime/EnvironmentDefaults.cpp b/flang/lib/Optimizer/Builder/Runtime/EnvironmentDefaults.cpp
index a11b9339681e3b..6e280ac0c06cd2 100755
--- a/flang/lib/Optimizer/Builder/Runtime/EnvironmentDefaults.cpp
+++ b/flang/lib/Optimizer/Builder/Runtime/EnvironmentDefaults.cpp
@@ -13,7 +13,7 @@
#include "flang/Optimizer/Support/InternalNames.h"
#include "llvm/ADT/ArrayRef.h"
-void fir::runtime::genEnvironmentDefaults(
+fir::GlobalOp fir::runtime::genEnvironmentDefaults(
fir::FirOpBuilder &builder, mlir::Location loc,
const std::vector<Fortran::lower::EnvironmentDefault> &envDefaults) {
std::string envDefaultListPtrName =
@@ -34,14 +34,13 @@ void fir::runtime::genEnvironmentDefaults(
// If no defaults were specified, initialize with a null pointer.
if (envDefaults.empty()) {
- builder.createGlobalConstant(
+ return builder.createGlobalConstant(
loc, envDefaultListRefTy, envDefaultListPtrName,
[&](fir::FirOpBuilder &builder) {
mlir::Value nullVal =
builder.createNullConstant(loc, envDefaultListRefTy);
builder.create<fir::HasValueOp>(loc, nullVal);
});
- return;
}
// Create the Item list.
@@ -99,7 +98,7 @@ void fir::runtime::genEnvironmentDefaults(
envDefaultListBuilder, linkOnce);
// Define the pointer to the list used by the runtime.
- builder.createGlobalConstant(
+ return builder.createGlobalConstant(
loc, envDefaultListRefTy, envDefaultListPtrName,
[&](fir::FirOpBuilder &builder) {
mlir::Value addr = builder.create<fir::AddrOfOp>(
diff --git a/flang/lib/Optimizer/Builder/Runtime/Main.cpp b/flang/lib/Optimizer/Builder/Runtime/Main.cpp
new file mode 100644
index 00000000000000..93d082b8094eb6
--- /dev/null
+++ b/flang/lib/Optimizer/Builder/Runtime/Main.cpp
@@ -0,0 +1,62 @@
+//===-- Main.cpp - generate main runtime API calls ----------------*- C++
+//-*-===//
+//
+// 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 "flang/Optimizer/Builder/Runtime/Main.h"
+#include "flang/Optimizer/Builder/BoxValue.h"
+#include "flang/Optimizer/Builder/FIRBuilder.h"
+#include "flang/Optimizer/Builder/Runtime/RTBuilder.h"
+#include "flang/Optimizer/Dialect/FIROps.h"
+#include "flang/Optimizer/Dialect/FIRType.h"
+#include "flang/Runtime/main.h"
+#include "flang/Runtime/stop.h"
+
+using namespace Fortran::runtime;
+
+/// Create a `int main(...)` that calls the Fortran entry point
+void fir::runtime::genMain(fir::FirOpBuilder &builder, mlir::Location loc,
+ fir::GlobalOp &env) {
+ auto *context = builder.getContext();
+ auto argcTy = builder.getDefaultIntegerType();
+ auto ptrTy = mlir::LLVM::LLVMPointerType::get(context);
+
+ // void ProgramStart(int argc, char** argv, char** envp, _QQEnvironmentDefaults* env)
+ auto startFn = builder.createFunction(
+ loc, RTNAME_STRING(ProgramStart),
+ mlir::FunctionType::get(context, {argcTy, ptrTy, ptrTy, ptrTy}, {}));
+ // void ProgramStop()
+ auto stopFn =
+ builder.createFunction(loc, RTNAME_STRING(ProgramEndStatement),
+ mlir::FunctionType::get(context, {}, {}));
+
+ // int main(int argc, char** argv, char** envp)
+ auto mainFn = builder.createFunction(
+ loc, "main",
+ mlir::FunctionType::get(context, {argcTy, ptrTy, ptrTy}, argcTy));
+ // void _QQmain()
+ auto qqMainFn = builder.createFunction(loc, "_QQmain",
+ mlir::FunctionType::get(context, {}, {}));
+
+ mainFn.setPublic();
+
+ auto *block = mainFn.addEntryBlock();
+ mlir::OpBuilder::InsertionGuard insertGuard(builder);
+ builder.setInsertionPointToStart(block);
+
+ llvm::SmallVector<mlir::Value, 4> args (block->getArguments());
+ auto envAddr =
+ builder.create<fir::AddrOfOp>(loc, env.getType(), env.getSymbol());
+ args.push_back(envAddr);
+
+ builder.create<fir::CallOp>(loc, startFn, args);
+ builder.create<fir::CallOp>(loc, qqMainFn);
+ builder.create<fir::CallOp>(loc, stopFn);
+
+ mlir::Value ret = builder.createIntegerConstant(loc, argcTy, 0);
+ builder.create<mlir::func::ReturnOp>(loc, ret);
+}
diff --git a/flang/runtime/CMakeLists.txt b/flang/runtime/CMakeLists.txt
index bdd0e07bbfd4d1..9f25c5dfcad11d 100644
--- a/flang/runtime/CMakeLists.txt
+++ b/flang/runtime/CMakeLists.txt
@@ -103,7 +103,6 @@ append(${NO_LTO_FLAGS} CMAKE_CXX_FLAGS)
add_definitions(-U_GLIBCXX_ASSERTIONS)
add_definitions(-U_LIBCPP_ENABLE_ASSERTIONS)
-add_subdirectory(FortranMain)
add_subdirectory(Float128Math)
set(sources
diff --git a/flang/runtime/FortranMain/CMakeLists.txt b/flang/runtime/FortranMain/CMakeLists.txt
deleted file mode 100644
index deb7bd10acf512..00000000000000
--- a/flang/runtime/FortranMain/CMakeLists.txt
+++ /dev/null
@@ -1,23 +0,0 @@
-add_flang_library(Fortran_main STATIC INSTALL_WITH_TOOLCHAIN
- Fortran_main.c
-)
-if (DEFINED MSVC)
- set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreaded)
- add_flang_library(Fortran_main.static STATIC INSTALL_WITH_TOOLCHAIN
- Fortran_main.c
- )
- set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreadedDLL)
- add_flang_library(Fortran_main.dynamic S...
[truncated]
|
|
@llvm/pr-subscribers-clang-driver Author: David Truby (DavidTruby) ChangesThis patch changes the behaviour for flang to only create and link to a This means that flang-new can be used to link even when the program is Patch is 30.69 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/89938.diff 23 Files Affected:
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 922bda721dc780..4b852b297a6b99 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -6582,12 +6582,6 @@ def J : JoinedOrSeparate<["-"], "J">,
Group<gfortran_Group>,
Alias<module_dir>;
-let Visibility = [FlangOption] in {
-def no_fortran_main : Flag<["-"], "fno-fortran-main">,
- Visibility<[FlangOption]>, Group<f_Group>,
- HelpText<"Do not include Fortran_main.a (provided by Flang) when linking">;
-} // let Visibility = [ FlangOption ]
-
//===----------------------------------------------------------------------===//
// FC1 Options
//===----------------------------------------------------------------------===//
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index b65b96db16bd79..fec11c7e716fdf 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1191,118 +1191,10 @@ bool tools::addOpenMPRuntime(const Compilation &C, ArgStringList &CmdArgs,
return true;
}
-/// Determines if --whole-archive is active in the list of arguments.
-static bool isWholeArchivePresent(const ArgList &Args) {
- bool WholeArchiveActive = false;
- for (auto *Arg : Args.filtered(options::OPT_Wl_COMMA)) {
- if (Arg) {
- for (StringRef ArgValue : Arg->getValues()) {
- if (ArgValue == "--whole-archive")
- WholeArchiveActive = true;
- if (ArgValue == "--no-whole-archive")
- WholeArchiveActive = false;
- }
- }
- }
-
- return WholeArchiveActive;
-}
-
-/// Determine if driver is invoked to create a shared object library (-static)
-static bool isSharedLinkage(const ArgList &Args) {
- return Args.hasArg(options::OPT_shared);
-}
-
-/// Determine if driver is invoked to create a static object library (-shared)
-static bool isStaticLinkage(const ArgList &Args) {
- return Args.hasArg(options::OPT_static);
-}
-
-/// Add Fortran runtime libs for MSVC
-static void addFortranRuntimeLibsMSVC(const ArgList &Args,
- llvm::opt::ArgStringList &CmdArgs) {
- unsigned RTOptionID = options::OPT__SLASH_MT;
- if (auto *rtl = Args.getLastArg(options::OPT_fms_runtime_lib_EQ)) {
- RTOptionID = llvm::StringSwitch<unsigned>(rtl->getValue())
- .Case("static", options::OPT__SLASH_MT)
- .Case("static_dbg", options::OPT__SLASH_MTd)
- .Case("dll", options::OPT__SLASH_MD)
- .Case("dll_dbg", options::OPT__SLASH_MDd)
- .Default(options::OPT__SLASH_MT);
- }
- switch (RTOptionID) {
- case options::OPT__SLASH_MT:
- CmdArgs.push_back("/WHOLEARCHIVE:Fortran_main.static.lib");
- break;
- case options::OPT__SLASH_MTd:
- CmdArgs.push_back("/WHOLEARCHIVE:Fortran_main.static_dbg.lib");
- break;
- case options::OPT__SLASH_MD:
- CmdArgs.push_back("/WHOLEARCHIVE:Fortran_main.dynamic.lib");
- break;
- case options::OPT__SLASH_MDd:
- CmdArgs.push_back("/WHOLEARCHIVE:Fortran_main.dynamic_dbg.lib");
- break;
- }
-}
-
-// Add FortranMain runtime lib
-static void addFortranMain(const ToolChain &TC, const ArgList &Args,
- llvm::opt::ArgStringList &CmdArgs) {
- // 0. Shared-library linkage
- // If we are attempting to link a library, we should not add
- // -lFortran_main.a to the link line, as the `main` symbol is not
- // required for a library and should also be provided by one of
- // the translation units of the code that this shared library
- // will be linked against eventually.
- if (isSharedLinkage(Args) || isStaticLinkage(Args)) {
- return;
- }
-
- // 1. MSVC
- if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
- addFortranRuntimeLibsMSVC(Args, CmdArgs);
- return;
- }
-
- // 2. GNU and similar
- const Driver &D = TC.getDriver();
- const char *FortranMainLinkFlag = "-lFortran_main";
-
- // Warn if the user added `-lFortran_main` - this library is an implementation
- // detail of Flang and should be handled automaticaly by the driver.
- for (const char *arg : CmdArgs) {
- if (strncmp(arg, FortranMainLinkFlag, strlen(FortranMainLinkFlag)) == 0)
- D.Diag(diag::warn_drv_deprecated_custom)
- << FortranMainLinkFlag
- << "see the Flang driver documentation for correct usage";
- }
-
- // The --whole-archive option needs to be part of the link line to make
- // sure that the main() function from Fortran_main.a is pulled in by the
- // linker. However, it shouldn't be used if it's already active.
- // TODO: Find an equivalent of `--whole-archive` for Darwin and AIX.
- if (!isWholeArchivePresent(Args) && !TC.getTriple().isMacOSX() &&
- !TC.getTriple().isOSAIX()) {
- CmdArgs.push_back("--whole-archive");
- CmdArgs.push_back(FortranMainLinkFlag);
- CmdArgs.push_back("--no-whole-archive");
- return;
- }
-
- CmdArgs.push_back(FortranMainLinkFlag);
-}
-
/// Add Fortran runtime libs
void tools::addFortranRuntimeLibs(const ToolChain &TC, const ArgList &Args,
llvm::opt::ArgStringList &CmdArgs) {
- // 1. Link FortranMain
- // FortranMain depends on FortranRuntime, so needs to be listed first. If
- // -fno-fortran-main has been passed, skip linking Fortran_main.a
- if (!Args.hasArg(options::OPT_no_fortran_main))
- addFortranMain(TC, Args, CmdArgs);
-
- // 2. Link FortranRuntime and FortranDecimal
+ // Link FortranRuntime and FortranDecimal
// These are handled earlier on Windows by telling the frontend driver to
// add the correct libraries to link against as dependents in the object
// file.
diff --git a/clang/lib/Driver/ToolChains/Flang.cpp b/clang/lib/Driver/ToolChains/Flang.cpp
index 6d93c1f3d7034a..8955b9fb653c2a 100644
--- a/clang/lib/Driver/ToolChains/Flang.cpp
+++ b/clang/lib/Driver/ToolChains/Flang.cpp
@@ -282,7 +282,6 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
assert(TC.getTriple().isKnownWindowsMSVCEnvironment() &&
"can only add VS runtime library on Windows!");
// if -fno-fortran-main has been passed, skip linking Fortran_main.a
- bool LinkFortranMain = !Args.hasArg(options::OPT_no_fortran_main);
if (TC.getTriple().isKnownWindowsMSVCEnvironment()) {
CmdArgs.push_back(Args.MakeArgString(
"--dependent-lib=" + TC.getCompilerRTBasename(Args, "builtins")));
@@ -300,8 +299,6 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
case options::OPT__SLASH_MT:
CmdArgs.push_back("-D_MT");
CmdArgs.push_back("--dependent-lib=libcmt");
- if (LinkFortranMain)
- CmdArgs.push_back("--dependent-lib=Fortran_main.static.lib");
CmdArgs.push_back("--dependent-lib=FortranRuntime.static.lib");
CmdArgs.push_back("--dependent-lib=FortranDecimal.static.lib");
break;
@@ -309,8 +306,6 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
CmdArgs.push_back("-D_MT");
CmdArgs.push_back("-D_DEBUG");
CmdArgs.push_back("--dependent-lib=libcmtd");
- if (LinkFortranMain)
- CmdArgs.push_back("--dependent-lib=Fortran_main.static_dbg.lib");
CmdArgs.push_back("--dependent-lib=FortranRuntime.static_dbg.lib");
CmdArgs.push_back("--dependent-lib=FortranDecimal.static_dbg.lib");
break;
@@ -318,8 +313,6 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
CmdArgs.push_back("-D_MT");
CmdArgs.push_back("-D_DLL");
CmdArgs.push_back("--dependent-lib=msvcrt");
- if (LinkFortranMain)
- CmdArgs.push_back("--dependent-lib=Fortran_main.dynamic.lib");
CmdArgs.push_back("--dependent-lib=FortranRuntime.dynamic.lib");
CmdArgs.push_back("--dependent-lib=FortranDecimal.dynamic.lib");
break;
@@ -328,8 +321,6 @@ static void processVSRuntimeLibrary(const ToolChain &TC, const ArgList &Args,
CmdArgs.push_back("-D_DEBUG");
CmdArgs.push_back("-D_DLL");
CmdArgs.push_back("--dependent-lib=msvcrtd");
- if (LinkFortranMain)
- CmdArgs.push_back("--dependent-lib=Fortran_main.dynamic_dbg.lib");
CmdArgs.push_back("--dependent-lib=FortranRuntime.dynamic_dbg.lib");
CmdArgs.push_back("--dependent-lib=FortranDecimal.dynamic_dbg.lib");
break;
diff --git a/flang/docs/FlangDriver.md b/flang/docs/FlangDriver.md
index ac120b4ff09b6d..351595ac0afdb7 100644
--- a/flang/docs/FlangDriver.md
+++ b/flang/docs/FlangDriver.md
@@ -179,46 +179,20 @@ like this:
```
$ flang -v -o example example.o
-"/usr/bin/ld" [...] example.o [...] "--whole-archive" "-lFortran_main"
-"--no-whole-archive" "-lFortranRuntime" "-lFortranDecimal" [...]
+"/usr/bin/ld" [...] example.o [...] "-lFortranRuntime" "-lFortranDecimal" [...]
```
The automatically added libraries are:
-* `Fortran_main`: Provides the main entry point `main` that then invokes
- `_QQmain` with the Fortran program unit. This library has a dependency to
- the `FortranRuntime` library.
* `FortranRuntime`: Provides most of the Flang runtime library.
* `FortranDecimal`: Provides operations for decimal numbers.
-The default is that, when using Flang as the linker, one of the Fortran
-translation units provides the program unit and therefore it is assumed that
-Fortran is the main code part (calling into C/C++ routines via `BIND (C)`
-interfaces). When composing the linker commandline, Flang uses
-`--whole-archive` and `--no-whole-archive` (Windows: `/WHOLEARCHIVE:`,
-Darwin & AIX: *not implemented yet*) to make sure that all for `Fortran_main`
-is processed by the linker. This is done to issue a proper error message when
-multiple definitions of `main` occur. This happens, for instance, when linking
-a code that has a Fortran program unit with a C/C++ code that also defines a
-`main` function. A user may be required to explicitly provide the C++ runtime
-libraries at link time (e.g., via `-lstdc++` for STL)
-
If the code is C/C++ based and invokes Fortran routines, one can either use Clang
or Flang as the linker driver. If Clang is used, it will automatically all
required runtime libraries needed by C++ (e.g., for STL) to the linker invocation.
In this case, one has to explicitly provide the Fortran runtime libraries
-`FortranRuntime` and/or `FortranDecimal`. An alternative is to use Flang to link
-and use the `-fno-fortran-main` flag. This flag removes
-`Fortran_main` from the linker stage and hence requires one of the C/C++
-translation units to provide a definition of the `main` function. In this case,
-it may be required to explicitly supply C++ runtime libraries as mentioned above.
-
-When creating shared or static libraries using Flang with `-shared` or `-static`
-flag, Fortran_main is automatically removed from the linker stage (i.e.,
-`-fno-fortran-main` is on by default). It is assumed that when creating a
-static or shared library, the generated library does not need a `main`
-function, as a final link stage will occur that will provide the `Fortran_main`
-library when creating the final executable.
+`FortranRuntime` and/or `FortranDecimal`. An alternative is to use Flang to link.
+In this case, it may be required to explicitly supply C++ runtime libraries.
On Darwin, the logical root where the system libraries are located (sysroot)
must be specified. This can be done with the CMake build flag `DEFAULT_SYSROOT`
diff --git a/flang/include/flang/Optimizer/Builder/Runtime/EnvironmentDefaults.h b/flang/include/flang/Optimizer/Builder/Runtime/EnvironmentDefaults.h
index 18a24bad396044..216d3bcec137e1 100755
--- a/flang/include/flang/Optimizer/Builder/Runtime/EnvironmentDefaults.h
+++ b/flang/include/flang/Optimizer/Builder/Runtime/EnvironmentDefaults.h
@@ -22,6 +22,7 @@
namespace fir {
class FirOpBuilder;
+class GlobalOp;
} // namespace fir
namespace mlir {
@@ -37,7 +38,7 @@ namespace fir::runtime {
/// Create the list of environment variable defaults for the runtime to set. The
/// form of the generated list is defined in the runtime header file
/// environment-default-list.h
-void genEnvironmentDefaults(
+fir::GlobalOp genEnvironmentDefaults(
fir::FirOpBuilder &builder, mlir::Location loc,
const std::vector<Fortran::lower::EnvironmentDefault> &envDefaults);
diff --git a/flang/include/flang/Optimizer/Builder/Runtime/Main.h b/flang/include/flang/Optimizer/Builder/Runtime/Main.h
new file mode 100644
index 00000000000000..62faf46e1fc778
--- /dev/null
+++ b/flang/include/flang/Optimizer/Builder/Runtime/Main.h
@@ -0,0 +1,28 @@
+//===-- Main.h - generate main runtime API calls ----------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef FORTRAN_OPTIMIZER_BUILDER_RUNTIME_MAIN_H
+#define FORTRAN_OPTIMIZER_BUILDER_RUNTIME_MAIN_H
+
+namespace mlir {
+class Location;
+} // namespace mlir
+
+namespace fir {
+class FirOpBuilder;
+class GlobalOp;
+} // namespace fir
+
+namespace fir::runtime {
+
+void genMain(fir::FirOpBuilder &builder, mlir::Location loc,
+ fir::GlobalOp &env);
+
+}
+
+#endif // FORTRAN_OPTIMIZER_BUILDER_RUNTIME_MAIN_H
diff --git a/flang/lib/Lower/Bridge.cpp b/flang/lib/Lower/Bridge.cpp
index 8b62fe8c022f80..afb5496ff8bc29 100644
--- a/flang/lib/Lower/Bridge.cpp
+++ b/flang/lib/Lower/Bridge.cpp
@@ -36,6 +36,7 @@
#include "flang/Optimizer/Builder/Runtime/Character.h"
#include "flang/Optimizer/Builder/Runtime/Derived.h"
#include "flang/Optimizer/Builder/Runtime/EnvironmentDefaults.h"
+#include "flang/Optimizer/Builder/Runtime/Main.h"
#include "flang/Optimizer/Builder/Runtime/Ragged.h"
#include "flang/Optimizer/Builder/Runtime/Stop.h"
#include "flang/Optimizer/Builder/Todo.h"
@@ -359,8 +360,10 @@ class FirConverter : public Fortran::lower::AbstractConverter {
// not need to be generated even if no defaults are specified.
// However, generating main or changing when the runtime reads
// environment variables is required to do so.
- fir::runtime::genEnvironmentDefaults(*builder, toLocation(),
+ auto env = fir::runtime::genEnvironmentDefaults(*builder, toLocation(),
bridge.getEnvironmentDefaults());
+
+ fir::runtime::genMain(*builder, toLocation(), env);
});
finalizeOpenACCLowering();
diff --git a/flang/lib/Optimizer/Builder/CMakeLists.txt b/flang/lib/Optimizer/Builder/CMakeLists.txt
index 06339b116cd899..95f19ed4dfbdf8 100644
--- a/flang/lib/Optimizer/Builder/CMakeLists.txt
+++ b/flang/lib/Optimizer/Builder/CMakeLists.txt
@@ -24,6 +24,7 @@ add_flang_library(FIRBuilder
Runtime/Inquiry.cpp
Runtime/Intrinsics.cpp
Runtime/Numeric.cpp
+ Runtime/Main.cpp
Runtime/Pointer.cpp
Runtime/Ragged.cpp
Runtime/Reduction.cpp
diff --git a/flang/lib/Optimizer/Builder/Runtime/EnvironmentDefaults.cpp b/flang/lib/Optimizer/Builder/Runtime/EnvironmentDefaults.cpp
index a11b9339681e3b..6e280ac0c06cd2 100755
--- a/flang/lib/Optimizer/Builder/Runtime/EnvironmentDefaults.cpp
+++ b/flang/lib/Optimizer/Builder/Runtime/EnvironmentDefaults.cpp
@@ -13,7 +13,7 @@
#include "flang/Optimizer/Support/InternalNames.h"
#include "llvm/ADT/ArrayRef.h"
-void fir::runtime::genEnvironmentDefaults(
+fir::GlobalOp fir::runtime::genEnvironmentDefaults(
fir::FirOpBuilder &builder, mlir::Location loc,
const std::vector<Fortran::lower::EnvironmentDefault> &envDefaults) {
std::string envDefaultListPtrName =
@@ -34,14 +34,13 @@ void fir::runtime::genEnvironmentDefaults(
// If no defaults were specified, initialize with a null pointer.
if (envDefaults.empty()) {
- builder.createGlobalConstant(
+ return builder.createGlobalConstant(
loc, envDefaultListRefTy, envDefaultListPtrName,
[&](fir::FirOpBuilder &builder) {
mlir::Value nullVal =
builder.createNullConstant(loc, envDefaultListRefTy);
builder.create<fir::HasValueOp>(loc, nullVal);
});
- return;
}
// Create the Item list.
@@ -99,7 +98,7 @@ void fir::runtime::genEnvironmentDefaults(
envDefaultListBuilder, linkOnce);
// Define the pointer to the list used by the runtime.
- builder.createGlobalConstant(
+ return builder.createGlobalConstant(
loc, envDefaultListRefTy, envDefaultListPtrName,
[&](fir::FirOpBuilder &builder) {
mlir::Value addr = builder.create<fir::AddrOfOp>(
diff --git a/flang/lib/Optimizer/Builder/Runtime/Main.cpp b/flang/lib/Optimizer/Builder/Runtime/Main.cpp
new file mode 100644
index 00000000000000..93d082b8094eb6
--- /dev/null
+++ b/flang/lib/Optimizer/Builder/Runtime/Main.cpp
@@ -0,0 +1,62 @@
+//===-- Main.cpp - generate main runtime API calls ----------------*- C++
+//-*-===//
+//
+// 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 "flang/Optimizer/Builder/Runtime/Main.h"
+#include "flang/Optimizer/Builder/BoxValue.h"
+#include "flang/Optimizer/Builder/FIRBuilder.h"
+#include "flang/Optimizer/Builder/Runtime/RTBuilder.h"
+#include "flang/Optimizer/Dialect/FIROps.h"
+#include "flang/Optimizer/Dialect/FIRType.h"
+#include "flang/Runtime/main.h"
+#include "flang/Runtime/stop.h"
+
+using namespace Fortran::runtime;
+
+/// Create a `int main(...)` that calls the Fortran entry point
+void fir::runtime::genMain(fir::FirOpBuilder &builder, mlir::Location loc,
+ fir::GlobalOp &env) {
+ auto *context = builder.getContext();
+ auto argcTy = builder.getDefaultIntegerType();
+ auto ptrTy = mlir::LLVM::LLVMPointerType::get(context);
+
+ // void ProgramStart(int argc, char** argv, char** envp, _QQEnvironmentDefaults* env)
+ auto startFn = builder.createFunction(
+ loc, RTNAME_STRING(ProgramStart),
+ mlir::FunctionType::get(context, {argcTy, ptrTy, ptrTy, ptrTy}, {}));
+ // void ProgramStop()
+ auto stopFn =
+ builder.createFunction(loc, RTNAME_STRING(ProgramEndStatement),
+ mlir::FunctionType::get(context, {}, {}));
+
+ // int main(int argc, char** argv, char** envp)
+ auto mainFn = builder.createFunction(
+ loc, "main",
+ mlir::FunctionType::get(context, {argcTy, ptrTy, ptrTy}, argcTy));
+ // void _QQmain()
+ auto qqMainFn = builder.createFunction(loc, "_QQmain",
+ mlir::FunctionType::get(context, {}, {}));
+
+ mainFn.setPublic();
+
+ auto *block = mainFn.addEntryBlock();
+ mlir::OpBuilder::InsertionGuard insertGuard(builder);
+ builder.setInsertionPointToStart(block);
+
+ llvm::SmallVector<mlir::Value, 4> args (block->getArguments());
+ auto envAddr =
+ builder.create<fir::AddrOfOp>(loc, env.getType(), env.getSymbol());
+ args.push_back(envAddr);
+
+ builder.create<fir::CallOp>(loc, startFn, args);
+ builder.create<fir::CallOp>(loc, qqMainFn);
+ builder.create<fir::CallOp>(loc, stopFn);
+
+ mlir::Value ret = builder.createIntegerConstant(loc, argcTy, 0);
+ builder.create<mlir::func::ReturnOp>(loc, ret);
+}
diff --git a/flang/runtime/CMakeLists.txt b/flang/runtime/CMakeLists.txt
index bdd0e07bbfd4d1..9f25c5dfcad11d 100644
--- a/flang/runtime/CMakeLists.txt
+++ b/flang/runtime/CMakeLists.txt
@@ -103,7 +103,6 @@ append(${NO_LTO_FLAGS} CMAKE_CXX_FLAGS)
add_definitions(-U_GLIBCXX_ASSERTIONS)
add_definitions(-U_LIBCPP_ENABLE_ASSERTIONS)
-add_subdirectory(FortranMain)
add_subdirectory(Float128Math)
set(sources
diff --git a/flang/runtime/FortranMain/CMakeLists.txt b/flang/runtime/FortranMain/CMakeLists.txt
deleted file mode 100644
index deb7bd10acf512..00000000000000
--- a/flang/runtime/FortranMain/CMakeLists.txt
+++ /dev/null
@@ -1,23 +0,0 @@
-add_flang_library(Fortran_main STATIC INSTALL_WITH_TOOLCHAIN
- Fortran_main.c
-)
-if (DEFINED MSVC)
- set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreaded)
- add_flang_library(Fortran_main.static STATIC INSTALL_WITH_TOOLCHAIN
- Fortran_main.c
- )
- set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreadedDLL)
- add_flang_library(Fortran_main.dynamic S...
[truncated]
|
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
DavidTruby
requested review from
pawosm-arm,
sscalpone,
DanielCChen,
kkwli,
jeanPerier and
vzakhari
klausler
approved these changes
Apr 24, 2024
| @@ -0,0 +1,63 @@ | |||
| //===-- Main.cpp - generate main runtime API calls ----------------*- C++ | |||
There was a problem hiding this comment.
This header comment needs to be cleaned up.
kkwli
approved these changes
Apr 25, 2024
| @@ -24,6 +24,7 @@ add_flang_library(FIRBuilder | |||
| Runtime/Inquiry.cpp | |||
| Runtime/Intrinsics.cpp | |||
| Runtime/Numeric.cpp | |||
| Runtime/Main.cpp | |||
There was a problem hiding this comment.
I think this list is in alphabetical order?
tblah
reviewed
Apr 25, 2024
There was a problem hiding this comment.
Thanks for this. I'm sure it will give a big improvement to the experience of building applications with flang.
Code changes look good to me. I'm worried about how this could break existing builds using -fno-fortran-main and -lFortran_main. Do you have a transition plan for this?
| @@ -6582,12 +6582,6 @@ def J : JoinedOrSeparate<["-"], "J">, | |||
| Group<gfortran_Group>, | |||
| Alias<module_dir>; | |||
|
|
|||
| let Visibility = [FlangOption] in { | |||
| def no_fortran_main : Flag<["-"], "fno-fortran-main">, | |||
There was a problem hiding this comment.
Will this break existing build systems configured to use this flag?
Comment on lines
-1272
to
-1279
| // Warn if the user added `-lFortran_main` - this library is an implementation | ||
| // detail of Flang and should be handled automaticaly by the driver. | ||
| for (const char *arg : CmdArgs) { | ||
| if (strncmp(arg, FortranMainLinkFlag, strlen(FortranMainLinkFlag)) == 0) | ||
| D.Diag(diag::warn_drv_deprecated_custom) | ||
| << FortranMainLinkFlag | ||
| << "see the Flang driver documentation for correct usage"; | ||
| } |
There was a problem hiding this comment.
Removing the Fortran_main library could also break existing builds, but I think it is more reasonable because it was deprecated since the last release.
|
This change will also break backward compatibility that the old object file that contain |
|
Great work David, thanks! Could you add some documentation explaining where Also, IMHO it would be good to advertise this on Discourse (thinking specifically about |
In mixed-source compilation where there's no I've already posted about this on discourse, you can see the discussion here: https://discourse.llvm.org/t/rfc-link-to-fortran-main-using-embedded-linker-flags/77596. I should have put that in the PR comment! |
|
As regards the backwards compatibility break here, I guess my take is that this change needs to happen some time and sooner is always going to be better than later. While we are still called flang-new and marked experimental I'm inclined to think we should just rip the band aid. We could leave |
tblah
approved these changes
Apr 26, 2024
pawosm-arm
approved these changes
Apr 26, 2024
DanielCChen
approved these changes
Apr 26, 2024
This patch changes the behaviour for flang to only create and link to a `main` entry point when the Fortran code has a program statement in it. This means that flang-new can be used to link even when the program is a mixed C/Fortran code with `main` present in C and no entry point present in Fortran.
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This file was originally removed in llvm#89504 and then accidentally re-added in llvm#89938.
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This patch changes the behaviour for flang to only create and link to a
mainentry point when the Fortran code has a program statement in it.This means that flang-new can be used to link even when the program is
a mixed C/Fortran code with
mainpresent in C and no entry pointpresent in Fortran.
This also removes the
-fno-fortran-mainflag as this no longer has any functionality.