Teach Clang to emit address-significance tables.

[pcc]

Summary

By default, we emit an address-significance table on all ELF
targets when the integrated assembler is enabled. The emission of an
address-significance table can be controlled with the -faddrsig and
-fno-addrsig flags.

Depends on D48143

[pcc]

• Add some additional driver tests

[rsmith]

Please add documentation and release notes for this flag too.

clang/include/clang/Driver/Options.td

def fno_profile_generate : Flag<["-"], "fno-profile-generate">,
     Group<f_Group>, Flags<[DriverOption]>,
     HelpText<"Disable generation of profile instrumentation.">;
 def fno_profile_instr_use : Flag<["-"], "fno-profile-instr-use">,
     Group<f_Group>, Flags<[DriverOption]>,
     HelpText<"Disable using instrumentation data for profile-guided optimization">;
 def fno_profile_use : Flag<["-"], "fno-profile-use">,
     Alias<fno_profile_instr_use>;
 
+def faddrsig : Flag<["-"], "faddrsig">, Group<f_Group>, Flags<[CoreOption, CC1Option]>,
+  HelpText<"Emit an address-significance table">;
+def fno_addrsig : Flag<["-"], "fno-addrsig">, Group<f_Group>, Flags<[CoreOption]>,
+  HelpText<"Don't emit an address-significance table">;
 def fblocks : Flag<["-"], "fblocks">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Enable the 'blocks' language feature">;
 def fbootclasspath_EQ : Joined<["-"], "fbootclasspath=">, Group<f_Group>;
 def fborland_extensions : Flag<["-"], "fborland-extensions">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Accept non-standard constructs supported by the Borland compiler">;
 def fbuiltin : Flag<["-"], "fbuiltin">, Group<f_Group>;
 def fbuiltin_module_map : Flag <["-"], "fbuiltin-module-map">, Group<f_Group>,
   Flags<[DriverOption]>, HelpText<"Load the clang builtins module map file.">;

clang/include/clang/Frontend/CodeGenOptions.def

 CODEGENOPT(NoPLT, 1, 0)
 
 /// Whether to embed source in DWARF debug line section.
 CODEGENOPT(EmbedSource, 1, 0)
 
 /// Whether to emit all vtables
 CODEGENOPT(ForceEmitVTables, 1, 0)
 
+/// Whether to emit an address-significance table into the object file.
+CODEGENOPT(Addrsig, 1, 0)
+
 
 #undef CODEGENOPT
 #undef ENUM_CODEGENOPT
 #undef VALUE_CODEGENOPT
 

clang/lib/CodeGen/BackendUtil.cpp

static void initTargetOptions(llvm::TargetOptions &Options,
   Options.StackAlignmentOverride = CodeGenOpts.StackAlignment;
   Options.FunctionSections = CodeGenOpts.FunctionSections;
   Options.DataSections = CodeGenOpts.DataSections;
   Options.UniqueSectionNames = CodeGenOpts.UniqueSectionNames;
   Options.EmulatedTLS = CodeGenOpts.EmulatedTLS;
   Options.ExplicitEmulatedTLS = CodeGenOpts.ExplicitEmulatedTLS;
   Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
   Options.EmitStackSizeSection = CodeGenOpts.StackSizeSection;
+  Options.EmitAddrsig = CodeGenOpts.Addrsig;
 
   if (CodeGenOpts.EnableSplitDwarf)
     Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
   Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
   Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
   Options.MCOptions.MCUseDwarfDirectory = !CodeGenOpts.NoDwarfDirectoryAsm;
   Options.MCOptions.MCNoExecStack = CodeGenOpts.NoExecStack;
   Options.MCOptions.MCIncrementalLinkerCompatible =

clang/lib/Driver/ToolChains/Clang.cpp

if (Arg *A = Args.getLastArg(options::OPT_fforce_enable_int128,
     if (A->getOption().matches(options::OPT_fforce_enable_int128))
       CmdArgs.push_back("-fforce-enable-int128");
   }
 
   if (Args.hasFlag(options::OPT_fcomplete_member_pointers,
                    options::OPT_fno_complete_member_pointers, false))
     CmdArgs.push_back("-fcomplete-member-pointers");
 
+  if (Args.hasFlag(options::OPT_faddrsig, options::OPT_fno_addrsig,
+                   getToolChain().getTriple().isOSBinFormatELF() &&
+                       getToolChain().useIntegratedAs()))
+    CmdArgs.push_back("-faddrsig");
+
   // Finally add the compile command to the compilation.
   if (Args.hasArg(options::OPT__SLASH_fallback) &&
       Output.getType() == types::TY_Object &&
       (InputType == types::TY_C || InputType == types::TY_CXX)) {
     auto CLCommand =
         getCLFallback()->GetCommand(C, JA, Output, Inputs, Args, LinkingOutput);
     C.addCommand(llvm::make_unique<FallbackCommand>(
         JA, *this, Exec, CmdArgs, Inputs, std::move(CLCommand)));

clang/lib/Frontend/CompilerInvocation.cpp

static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
 
   Opts.Backchain = Args.hasArg(OPT_mbackchain);
 
   Opts.EmitCheckPathComponentsToStrip = getLastArgIntValue(
       Args, OPT_fsanitize_undefined_strip_path_components_EQ, 0, Diags);
 
   Opts.EmitVersionIdentMetadata = Args.hasFlag(OPT_Qy, OPT_Qn, true);
 
+  Opts.Addrsig = Args.hasArg(OPT_faddrsig);
+
   return Success;
 }
 
 static void ParseDependencyOutputArgs(DependencyOutputOptions &Opts,
                                       ArgList &Args) {
   Opts.OutputFile = Args.getLastArgValue(OPT_dependency_file);
   Opts.Targets = Args.getAllArgValues(OPT_MT);
   Opts.IncludeSystemHeaders = Args.hasArg(OPT_sys_header_deps);

clang/test/CodeGen/addrsig.c

+// RUN: %clang_cc1 -triple=x86_64-unknown-linux -S %s -faddrsig -O -o - | FileCheck --check-prefix=ADDRSIG %s
+// RUN: %clang_cc1 -triple=x86_64-unknown-linux -S %s -O -o - | FileCheck --check-prefix=NO-ADDRSIG %s
+
+// ADDRSIG: .addrsig
+// ADDRSIG: .addrsig_sym g1
+// ADDRSIG-NOT: .addrsig_sym g2
+
+// NO-ADDRSIG-NOT: .addrsig
+
+extern const int g1[], g2[];
+
+const int *f1() {
+  return g1;
+}
+
+int f2() {
+  return g2[0];
+}

clang/test/Driver/addrsig.c

+// RUN: %clang -### -target x86_64-unknown-linux -c %s 2>&1 | FileCheck -check-prefix=ADDRSIG %s
+// RUN: %clang -### -target x86_64-unknown-linux -fno-integrated-as -gz -c %s 2>&1 | FileCheck -check-prefix=NO-ADDRSIG %s
+// RUN: %clang -### -target x86_64-apple-darwin -c %s 2>&1 | FileCheck -check-prefix=NO-ADDRSIG %s
+
+// ADDRSIG: -faddrsig
+// NO-ADDRSIG-NOT: -faddrsig