[flang-commits] [clang] [flang] [flang] Support -ffunction-sections and -fdata-sections. (PR #199731)
Abid Qadeer via flang-commits
flang-commits at lists.llvm.org
Tue May 26 10:00:50 PDT 2026
https://github.com/abidh created https://github.com/llvm/llvm-project/pull/199731
Wire the flags through the driver, frontend, and TargetMachine, and add driver and codegen lit tests.
Fixes https://github.com/llvm/llvm-project/issues/163550
>From b865c3605d942dc7fbf91db0468f57790b5d0cad Mon Sep 17 00:00:00 2001
From: Abid Qadeer <haqadeer at amd.com>
Date: Tue, 26 May 2026 17:17:34 +0100
Subject: [PATCH] [flang] Support -ffunction-sections and -fdata-sections
Wire the flags through the driver, frontend, and TargetMachine, and add driver and codegen lit tests.
---
clang/include/clang/Options/Options.td | 8 ++--
clang/lib/Driver/ToolChains/Flang.cpp | 12 ++++++
.../include/flang/Frontend/CodeGenOptions.def | 3 ++
flang/lib/Frontend/CompilerInstance.cpp | 2 +
flang/lib/Frontend/CompilerInvocation.cpp | 8 ++++
.../Driver/code-gen-function-sections.f90 | 32 +++++++++++++++
flang/test/Driver/function-sections.f90 | 39 +++++++++++++++++++
7 files changed, 100 insertions(+), 4 deletions(-)
create mode 100644 flang/test/Driver/code-gen-function-sections.f90
create mode 100644 flang/test/Driver/function-sections.f90
diff --git a/clang/include/clang/Options/Options.td b/clang/include/clang/Options/Options.td
index 753e3ac1b74a5..358ece91e0e9c 100644
--- a/clang/include/clang/Options/Options.td
+++ b/clang/include/clang/Options/Options.td
@@ -4825,9 +4825,9 @@ defm zero_initialized_in_bss : BoolFOption<"zero-initialized-in-bss",
PosFlag<SetFalse>>;
defm function_sections : BoolFOption<"function-sections",
CodeGenOpts<"FunctionSections">, DefaultFalse,
- PosFlag<SetTrue, [], [ClangOption, CC1Option],
+ PosFlag<SetTrue, [], [ClangOption, CC1Option, FlangOption, FC1Option],
"Place each function in its own section">,
- NegFlag<SetFalse>>;
+ NegFlag<SetFalse, [], [FlangOption, FC1Option]>>;
defm basic_block_address_map : BoolFOption<"basic-block-address-map",
CodeGenOpts<"BBAddrMap">, DefaultFalse,
PosFlag<SetTrue, [], [CC1Option], "Emit the basic block address map section.">,
@@ -4840,9 +4840,9 @@ def fbasic_block_sections_EQ : Joined<["-"], "fbasic-block-sections=">, Group<f_
MarshallingInfoString<CodeGenOpts<"BBSections">, [{"none"}]>;
defm data_sections : BoolFOption<"data-sections",
CodeGenOpts<"DataSections">, DefaultFalse,
- PosFlag<SetTrue, [], [ClangOption, CC1Option],
+ PosFlag<SetTrue, [], [ClangOption, CC1Option, FlangOption, FC1Option],
"Place each data in its own section">,
- NegFlag<SetFalse>>;
+ NegFlag<SetFalse, [], [FlangOption, FC1Option]>>;
defm experimental_call_graph_section
: BoolFOption<"experimental-call-graph-section",
CodeGenOpts<"CallGraphSection">, DefaultFalse,
diff --git a/clang/lib/Driver/ToolChains/Flang.cpp b/clang/lib/Driver/ToolChains/Flang.cpp
index 4c722a2e021eb..4c2282347c36b 100644
--- a/clang/lib/Driver/ToolChains/Flang.cpp
+++ b/clang/lib/Driver/ToolChains/Flang.cpp
@@ -262,6 +262,18 @@ void Flang::addCodegenOptions(const ArgList &Args,
options::OPT_fstack_repack_arrays, options::OPT_fno_stack_repack_arrays,
options::OPT_ftime_report, options::OPT_ftime_report_EQ,
options::OPT_funroll_loops, options::OPT_fno_unroll_loops});
+
+ const llvm::Triple &Triple = getToolChain().getEffectiveTriple();
+ bool UseSeparateSections = isUseSeparateSections(Triple);
+ if (Args.hasFlag(options::OPT_ffunction_sections,
+ options::OPT_fno_function_sections, UseSeparateSections))
+ CmdArgs.push_back("-ffunction-sections");
+
+ bool HasDefaultDataSections = Triple.isOSBinFormatXCOFF();
+ if (Args.hasFlag(options::OPT_fdata_sections, options::OPT_fno_data_sections,
+ UseSeparateSections || HasDefaultDataSections))
+ CmdArgs.push_back("-fdata-sections");
+
if (Args.hasArg(options::OPT_fcoarray))
CmdArgs.push_back("-fcoarray");
}
diff --git a/flang/include/flang/Frontend/CodeGenOptions.def b/flang/include/flang/Frontend/CodeGenOptions.def
index 17b8e61649da9..d8bbb94bd8cde 100644
--- a/flang/include/flang/Frontend/CodeGenOptions.def
+++ b/flang/include/flang/Frontend/CodeGenOptions.def
@@ -35,6 +35,9 @@ CODEGENOPT(InstrumentFunctions, 1, 0) ///< Set when -finstrument_functions is
CODEGENOPT(DisableIntegratedAS, 1, 0) ///< -no-integrated-as
+CODEGENOPT(FunctionSections, 1, 0) ///< -ffunction-sections
+CODEGENOPT(DataSections, 1, 0) ///< -fdata-sections
+
CODEGENOPT(IsPIE, 1, 0) ///< PIE level is the same as PIC Level.
CODEGENOPT(PICLevel, 2, 0) ///< PIC level of the LLVM module.
CODEGENOPT(PrepareForFatLTO , 1, 0) ///< Set when -ffat-lto-objects is enabled.
diff --git a/flang/lib/Frontend/CompilerInstance.cpp b/flang/lib/Frontend/CompilerInstance.cpp
index 3e820d386f8a9..7f562b1c39027 100644
--- a/flang/lib/Frontend/CompilerInstance.cpp
+++ b/flang/lib/Frontend/CompilerInstance.cpp
@@ -385,6 +385,8 @@ bool CompilerInstance::setUpTargetMachine() {
tOpts.EnableAIXExtendedAltivecABI = targetOpts.EnableAIXExtendedAltivecABI;
tOpts.VecLib = convertDriverVectorLibraryToVectorLibrary(CGOpts.getVecLib());
tOpts.DisableIntegratedAS = CGOpts.DisableIntegratedAS;
+ tOpts.FunctionSections = CGOpts.FunctionSections;
+ tOpts.DataSections = CGOpts.DataSections;
targetMachine.reset(theTarget->createTargetMachine(
triple, /*CPU=*/targetOpts.cpu,
diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 9853fc600ff6a..cb6a7a85ad55f 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -360,6 +360,14 @@ static void parseCodeGenArgs(Fortran::frontend::CodeGenOptions &opts,
clang::options::OPT_fno_integrated_as, true))
opts.DisableIntegratedAS = 1;
+ opts.FunctionSections =
+ args.hasFlag(clang::options::OPT_ffunction_sections,
+ clang::options::OPT_fno_function_sections,
+ /*Default=*/false);
+ opts.DataSections = args.hasFlag(clang::options::OPT_fdata_sections,
+ clang::options::OPT_fno_data_sections,
+ /*Default=*/false);
+
if (const llvm::opt::Arg *a =
args.getLastArg(clang::options::OPT_mcode_object_version_EQ)) {
llvm::StringRef s = a->getValue();
diff --git a/flang/test/Driver/code-gen-function-sections.f90 b/flang/test/Driver/code-gen-function-sections.f90
new file mode 100644
index 0000000000000..722d2537ee8d9
--- /dev/null
+++ b/flang/test/Driver/code-gen-function-sections.f90
@@ -0,0 +1,32 @@
+! Test -ffunction-sections and -fdata-sections codegen (X86).
+
+! REQUIRES: x86-registered-target
+
+! RUN: %flang_fc1 -triple x86_64-unknown-linux-gnu -S -ffunction-sections \
+! RUN: -o - %s | FileCheck %s --check-prefix=FUNC-SECT
+! RUN: %flang_fc1 -triple x86_64-unknown-linux-gnu -S -o - %s \
+! RUN: | FileCheck %s --check-prefix=FUNC-PLAIN
+
+! RUN: %flang_fc1 -triple x86_64-unknown-linux-gnu -S -fdata-sections \
+! RUN: -o - %s | FileCheck %s --check-prefix=DATA-SECT
+! RUN: %flang_fc1 -triple x86_64-unknown-linux-gnu -S -o - %s \
+! RUN: | FileCheck %s --check-prefix=DATA-PLAIN
+
+module data_sect_mod
+ integer, save :: g = 1
+end module
+
+subroutine foo
+end subroutine
+
+program test
+ use data_sect_mod
+ call foo
+end program
+
+! FUNC-SECT: .section{{.*}}.text.
+! FUNC-PLAIN-NOT: .section{{.*}}.text.
+
+! DATA-SECT: .section{{.*}}.data.
+! DATA-PLAIN: .data
+! DATA-PLAIN-NOT: .section{{.*}}.data.
diff --git a/flang/test/Driver/function-sections.f90 b/flang/test/Driver/function-sections.f90
new file mode 100644
index 0000000000000..ff6a5fff1d13e
--- /dev/null
+++ b/flang/test/Driver/function-sections.f90
@@ -0,0 +1,39 @@
+! Test handling of -f(no-)function-sections and -f(no-)data-sections (driver).
+!
+! CHECK-FS: "-ffunction-sections"
+! CHECK-NOFS-NOT: "-ffunction-sections"
+! CHECK-DS: "-fdata-sections"
+! CHECK-NODS-NOT: "-fdata-sections"
+
+! RUN: %flang -### -c --target=x86_64-unknown-linux-gnu %s 2>&1 \
+! RUN: | FileCheck %s --check-prefix=CHECK-NOFS --check-prefix=CHECK-NODS
+
+! RUN: %flang -### -c --target=x86_64-unknown-linux-gnu %s \
+! RUN: -ffunction-sections 2>&1 | FileCheck %s --check-prefix=CHECK-FS
+
+! RUN: %flang -### -c --target=x86_64-unknown-linux-gnu %s \
+! RUN: -fno-function-sections 2>&1 | FileCheck %s --check-prefix=CHECK-NOFS
+
+! RUN: %flang -### -c --target=x86_64-unknown-linux-gnu %s \
+! RUN: -ffunction-sections -fno-function-sections 2>&1 \
+! RUN: | FileCheck %s --check-prefix=CHECK-NOFS
+
+! RUN: %flang -### -c --target=x86_64-unknown-linux-gnu %s \
+! RUN: -fno-function-sections -ffunction-sections 2>&1 \
+! RUN: | FileCheck %s --check-prefix=CHECK-FS
+
+! RUN: %flang -### -c --target=x86_64-unknown-linux-gnu %s \
+! RUN: -fdata-sections 2>&1 | FileCheck %s --check-prefix=CHECK-DS
+
+! RUN: %flang -### -c --target=x86_64-unknown-linux-gnu %s \
+! RUN: -fno-data-sections 2>&1 | FileCheck %s --check-prefix=CHECK-NODS
+
+! RUN: %flang -### -c --target=x86_64-unknown-linux-gnu %s \
+! RUN: -fdata-sections -fno-data-sections 2>&1 \
+! RUN: | FileCheck %s --check-prefix=CHECK-NODS
+
+! RUN: %flang -### -c --target=x86_64-unknown-linux-gnu %s \
+! RUN: -fno-data-sections -fdata-sections 2>&1 \
+! RUN: | FileCheck %s --check-prefix=CHECK-DS
+
+end program
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