[clang] Introduce CallGraphSection codegen option

This patch adds clang CodeGen option to emit callgraph section.
The `-fexperimental-call-graph-section` Driver flag is introduced to
control the `CallGraphSection` CodeGen option.

Pull Request: llvm#117037

Author: Prabhuk

clang/include/clang/Basic/CodeGenOptions.def

@@ -72,6 +72,8 @@ CODEGENOPT(EnableNoundefAttrs, 1, 0, Benign) ///< Enable emitting `noundef` attr
 CODEGENOPT(DebugPassManager, 1, 0, Benign) ///< Prints debug information for the new
                                            ///< pass manager.
 CODEGENOPT(DisableRedZone    , 1, 0, Benign) ///< Set when -mno-red-zone is enabled.
+CODEGENOPT(CallGraphSection, 1, 0, Benign) ///< Emit a call graph section into the
+                                           ///< object file.
 CODEGENOPT(EmitCallSiteInfo, 1, 0, Benign) ///< Emit call site info only in the case of
                                            ///< '-g' + 'O>0' level.
 CODEGENOPT(IndirectTlsSegRefs, 1, 0, Benign) ///< Set when -mno-tls-direct-seg-refs

clang/include/clang/Driver/Options.td

@@ -4440,6 +4440,12 @@ defm data_sections : BoolFOption<"data-sections",
   PosFlag<SetTrue, [], [ClangOption, CC1Option],
           "Place each data in its own section">,
   NegFlag<SetFalse>>;
+defm experimental_call_graph_section
+    : BoolFOption<"experimental-call-graph-section",
+                  CodeGenOpts<"CallGraphSection">, DefaultFalse,
+                  PosFlag<SetTrue, [], [ClangOption, CC1Option],
+                          "Emit a call graph section">,
+                  NegFlag<SetFalse>>;
 defm stack_size_section : BoolFOption<"stack-size-section",
   CodeGenOpts<"StackSizeSection">, DefaultFalse,
   PosFlag<SetTrue, [], [ClangOption, CC1Option],

clang/lib/CodeGen/BackendUtil.cpp

@@ -462,6 +462,7 @@ static bool initTargetOptions(const CompilerInstance &CI,
   Options.StackUsageOutput = CodeGenOpts.StackUsageOutput;
   Options.EmitAddrsig = CodeGenOpts.Addrsig;
   Options.ForceDwarfFrameSection = CodeGenOpts.ForceDwarfFrameSection;
+  Options.EmitCallGraphSection = CodeGenOpts.CallGraphSection;
   Options.EmitCallSiteInfo = CodeGenOpts.EmitCallSiteInfo;
   Options.EnableAIXExtendedAltivecABI = LangOpts.EnableAIXExtendedAltivecABI;
   Options.XRayFunctionIndex = CodeGenOpts.XRayFunctionIndex;

clang/lib/Driver/ToolChains/Clang.cpp

@@ -6478,6 +6478,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back(A->getValue());
   }
 
+  if (Args.hasFlag(options::OPT_fexperimental_call_graph_section,
+                   options::OPT_fno_experimental_call_graph_section, false))
+    CmdArgs.push_back("-fexperimental-call-graph-section");
+
   Args.addOptInFlag(CmdArgs, options::OPT_fstack_size_section,
                     options::OPT_fno_stack_size_section);
 

clang/lib/Driver/ToolChains/CommonArgs.cpp

@@ -1269,6 +1269,11 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
     CmdArgs.push_back(
         Args.MakeArgString(Twine(PluginOptPrefix) + "-stack-size-section"));
 
+  if (Args.hasFlag(options::OPT_fexperimental_call_graph_section,
+                   options::OPT_fno_experimental_call_graph_section, false))
+    CmdArgs.push_back(
+        Args.MakeArgString(Twine(PluginOptPrefix) + "-call-graph-section"));
+
   // Setup statistics file output.
   SmallString<128> StatsFile = getStatsFileName(Args, Output, *Input, D);
   if (!StatsFile.empty())

clang/test/Driver/call-graph-section.c

@@ -0,0 +1,5 @@
+// RUN: %clang -### -fexperimental-call-graph-section %s 2>&1 | FileCheck --check-prefix=CALL-GRAPH-SECTION %s
+// RUN: %clang -### -fexperimental-call-graph-section -fno-experimental-call-graph-section %s 2>&1 | FileCheck --check-prefix=NO-CALL-GRAPH-SECTION %s
+
+// CALL-GRAPH-SECTION: "-fexperimental-call-graph-section"
+// NO-CALL-GRAPH-SECTION-NOT: "-fexperimental-call-graph-section"