Add -funique-section-names and -fno-unique-section-names options.

For now -funique-section-names is the default, so no change in default behavior.

The total .o size in a build of llvm and clang goes from 241687775 to 230649031
bytes if -fno-unique-section-names is used.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@230031 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Driver/Options.td

@@ -1004,6 +1004,14 @@ def fdata_sections : Flag <["-"], "fdata-sections">, Group<f_Group>,
  Flags<[CC1Option]>, HelpText<"Place each data in its own section (ELF Only)">;
 def fno_data_sections : Flag <["-"], "fno-data-sections">, Group<f_Group>,
   Flags<[CC1Option]>;
+
+def funique_section_names : Flag <["-"], "funique-section-names">,
+  Group<f_Group>, Flags<[CC1Option]>,
+  HelpText<"Use unique names for text and data sections (ELF Only)">;
+def fno_unique_section_names : Flag <["-"], "fno-unique-section-names">,
+  Group<f_Group>, Flags<[CC1Option]>;
+
+
 def fdebug_types_section: Flag <["-"], "fdebug-types-section">, Group<f_Group>,
   Flags<[CC1Option]>, HelpText<"Place debug types in their own section (ELF Only)">;
 def fno_debug_types_section: Flag<["-"], "fno-debug-types-section">, Group<f_Group>,

include/clang/Frontend/CodeGenOptions.def

@@ -40,6 +40,7 @@ CODEGENOPT(CXAAtExit         , 1, 1) ///< Use __cxa_atexit for calling destructo
 CODEGENOPT(CXXCtorDtorAliases, 1, 0) ///< Emit complete ctors/dtors as linker
                                      ///< aliases to base ctors when possible.
 CODEGENOPT(DataSections      , 1, 0) ///< Set when -fdata-sections is enabled.
+CODEGENOPT(UniqueSectionNames, 1, 1) ///< Set for -funique-section-names.
 CODEGENOPT(DisableFPElim     , 1, 0) ///< Set when -fomit-frame-pointer is enabled.
 CODEGENOPT(DisableFree       , 1, 0) ///< Don't free memory.
 CODEGENOPT(DisableGCov       , 1, 0) ///< Don't run the GCov pass, for testing.

lib/CodeGen/BackendUtil.cpp

@@ -527,6 +527,7 @@ TargetMachine *EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
   Options.PositionIndependentExecutable = LangOpts.PIELevel != 0;
   Options.FunctionSections = CodeGenOpts.FunctionSections;
   Options.DataSections = CodeGenOpts.DataSections;
+  Options.UniqueSectionNames = CodeGenOpts.UniqueSectionNames;
 
   Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
   Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;

lib/Driver/Tools.cpp

@@ -3316,6 +3316,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back("-fdata-sections");
   }
 
+  if (!Args.hasFlag(options::OPT_funique_section_names,
+                    options::OPT_fno_unique_section_names, true))
+    CmdArgs.push_back("-fno-unique-section-names");
+
   Args.AddAllArgs(CmdArgs, options::OPT_finstrument_functions);
 
   if (Args.hasArg(options::OPT_fprofile_instr_generate) &&

lib/Frontend/CompilerInvocation.cpp

@@ -472,6 +472,9 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
                                        OPT_fno_function_sections, false);
   Opts.DataSections = Args.hasFlag(OPT_fdata_sections,
                                    OPT_fno_data_sections, false);
+  Opts.UniqueSectionNames = Args.hasFlag(OPT_funique_section_names,
+                                         OPT_fno_unique_section_names, true);
+
   Opts.MergeFunctions = Args.hasArg(OPT_fmerge_functions);
 
   Opts.MSVolatile = Args.hasArg(OPT_fms_volatile);

test/CodeGen/funique-sections.c

+// REQUIRES: x86-registered-target
+
+// RUN: %clang_cc1 -triple x86_64-pc-linux -S -ffunction-sections -fdata-sections -fno-unique-section-names  -o - < %s | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-pc-linux -S -ffunction-sections -fdata-sections -o - < %s | FileCheck %s --check-prefix=UNIQUE
+
+const int hello = 123;
+void world() {}
+
+// CHECK: .section .text,"ax",@progbits,unique
+// CHECK: .section .rodata,"a",@progbits,unique
+
+// UNIQUE: .section .text.world,"ax",@progbits
+// UNIQUE: .section .rodata.hello,"a",@progbits

test/Driver/function-sections.c

@@ -4,6 +4,8 @@
 // CHECK-NOFS-NOT: -ffunction-sections
 // CHECK-DS: -fdata-sections
 // CHECK-NODS-NOT: -fdata-sections
+// CHECK-US-NOT: -fno-unique-section-names
+// CHECK-NOUS: -fno-unique-section-names
 
 // RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1       \
 // RUN:     -target i386-unknown-linux \
@@ -60,3 +62,13 @@
 // RUN:     -fdata-sections -fno-data-sections -fdata-sections \
 // RUN:   | FileCheck --check-prefix=CHECK-DS %s
 
+
+// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1        \
+// RUN:     -target i386-unknown-linux \
+// RUN:     -funique-section-names \
+// RUN:   | FileCheck --check-prefix=CHECK-US %s
+
+// RUN: %clang -no-canonical-prefixes %s -### -fsyntax-only 2>&1        \
+// RUN:     -target i386-unknown-linux \
+// RUN:     -fno-unique-section-names \
+// RUN:   | FileCheck --check-prefix=CHECK-NOUS %s