[flang-commits] [clang] [flang] [flang][driver] add option to make all main program variable static (PR #121968)

[via flang-commits]

https://github.com/jeanPerier created https://github.com/llvm/llvm-project/pull/121968

None

>From f8683e46b58eee5828fced9a31294d72fc247baf Mon Sep 17 00:00:00 2001
From: Jean Perier <jperier at nvidia.com>
Date: Tue, 7 Jan 2025 09:30:17 -0800
Subject: [PATCH] [flang][driver] add option to make all main program variable
 static

---
 clang/include/clang/Driver/Options.td     |  3 +++
 clang/lib/Driver/ToolChains/Flang.cpp     |  3 ++-
 flang/lib/Frontend/CompilerInvocation.cpp |  5 +++++
 flang/test/Driver/fsave-main-program.f90  |  5 +++++
 flang/test/Lower/fsave-main-program.f90   | 10 ++++++++++
 5 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 flang/test/Driver/fsave-main-program.f90
 create mode 100644 flang/test/Lower/fsave-main-program.f90

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 0528104f055158..85d02edc935f0b 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -6945,6 +6945,9 @@ defm unsigned : OptInFC1FFlag<"unsigned", "Enables UNSIGNED type">;
 def fno_automatic : Flag<["-"], "fno-automatic">, Group<f_Group>,
   HelpText<"Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE">;
 
+def fsave_main_program : Flag<["-"], "fsave-main-program">, Group<f_Group>,
+  HelpText<"Place all variables from the main program in static memory (otherwise scalar may be placed on the stack)">;
+
 defm stack_arrays : BoolOptionWithoutMarshalling<"f", "stack-arrays",
   PosFlag<SetTrue, [], [ClangOption], "Attempt to allocate array temporaries on the stack, no matter their size">,
   NegFlag<SetFalse, [], [ClangOption], "Allocate array temporaries on the heap (default)">>;
diff --git a/clang/lib/Driver/ToolChains/Flang.cpp b/clang/lib/Driver/ToolChains/Flang.cpp
index 7034e5b475c1d3..75b10e88371ae7 100644
--- a/clang/lib/Driver/ToolChains/Flang.cpp
+++ b/clang/lib/Driver/ToolChains/Flang.cpp
@@ -57,7 +57,8 @@ void Flang::addFortranDialectOptions(const ArgList &Args,
                             options::OPT_fno_automatic,
                             options::OPT_fhermetic_module_files,
                             options::OPT_frealloc_lhs,
-                            options::OPT_fno_realloc_lhs});
+                            options::OPT_fno_realloc_lhs,
+                            options::OPT_fsave_main_program});
 }
 
 void Flang::addPreprocessingOptions(const ArgList &Args,
diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 79386c92d552ca..340efb1c63a5e5 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -766,6 +766,11 @@ static bool parseFrontendArgs(FrontendOptions &opts, llvm::opt::ArgList &args,
     opts.features.Enable(Fortran::common::LanguageFeature::DefaultSave);
   }
 
+  // -fsave-main-program
+  if (args.hasArg(clang::driver::options::OPT_fsave_main_program)) {
+    opts.features.Enable(Fortran::common::LanguageFeature::SaveMainProgram);
+  }
+
   if (args.hasArg(
           clang::driver::options::OPT_falternative_parameter_statement)) {
     opts.features.Enable(Fortran::common::LanguageFeature::OldStyleParameter);
diff --git a/flang/test/Driver/fsave-main-program.f90 b/flang/test/Driver/fsave-main-program.f90
new file mode 100644
index 00000000000000..bffdfd97911e80
--- /dev/null
+++ b/flang/test/Driver/fsave-main-program.f90
@@ -0,0 +1,5 @@
+! Check that the driver passes through -fsave-main-program:
+! RUN: %flang -### -S -fsave-main-program %s -o - 2>&1 | FileCheck %s
+! Check that the compiler accepts -fsave-main-program:
+! RUN: %flang_fc1 -emit-hlfir -fsave-main-program %s -o -
+! CHECK: "-fc1"{{.*}}"-fsave-main-program"
diff --git a/flang/test/Lower/fsave-main-program.f90 b/flang/test/Lower/fsave-main-program.f90
new file mode 100644
index 00000000000000..17fc1b02f5068f
--- /dev/null
+++ b/flang/test/Lower/fsave-main-program.f90
@@ -0,0 +1,10 @@
+! Test -fsave-main-program switch.
+! RUN: %flang_fc1 -emit-hlfir -o - %s | FileCheck --check-prefix=CHECK-DEFAULT %s
+! RUN: %flang_fc1 -fsave-main-program -emit-hlfir -o - %s | FileCheck --check-prefix=CHECK-SAVE %s
+program test
+integer :: i
+call foo(i)
+end
+
+!CHECK-DEFAULT-NOT: fir.global internal @_QFEi
+!CHECK-SAVE: fir.global internal @_QFEi