[PATCH] D137753: [Clang][p]Enable -p Functionality

[Michael Francis via Phabricator via cfe-commits]

francii created this revision.
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francii requested review of this revision.
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Herald added a project: clang.

This patch enables general, non-platform-specific `-p` functionality
into Clang to create parity with GCC. Specifically, this patch
creates a new CodeGen option for `-p` and allows it to be used
as an instrument for profiling.

A side effect of this change is that the CodeGen option for `-pg`
was renamed from `InstrumentForProfiling` to `InstrumentForProfilingGraph`,
as profiling with `-pg` provides call-graph information while `-p` does not.

The purpose of the `-p` flag is similar to that of `-pg`, but the
results are analyzed with the `prof` tool as opposed to the `gprof` tool.
More details can be found in this RFC post:
https://discourse.llvm.org/t/rfc-add-p-driver-support-to-clang/66013?u=francii

It is up to each vendor to implement their specific behaviour of `-p`.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D137753

Files:
  clang/include/clang/Basic/CodeGenOptions.def
  clang/include/clang/Driver/Options.td
  clang/lib/CodeGen/BackendUtil.cpp
  clang/lib/CodeGen/CodeGenFunction.cpp
  clang/lib/Driver/ToolChains/Clang.cpp


Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -521,7 +521,8 @@
 
 static bool useFramePointerForTargetByDefault(const ArgList &Args,
                                               const llvm::Triple &Triple) {
-  if (Args.hasArg(options::OPT_pg) && !Args.hasArg(options::OPT_mfentry))
+  if (Args.hasArg(options::OPT_p, options::OPT_pg) &&
+      !Args.hasArg(options::OPT_mfentry))
     return true;
 
   switch (Triple.getArch()) {
@@ -6268,6 +6269,7 @@
   Args.AddLastArg(CmdArgs, options::OPT_fms_hotpatch);
 
   if (TC.SupportsProfiling()) {
+    Args.AddLastArg(CmdArgs, options::OPT_p);
     Args.AddLastArg(CmdArgs, options::OPT_pg);
 
     llvm::Triple::ArchType Arch = TC.getArch();
@@ -7388,7 +7390,7 @@
     C.getJobs().getJobs().back()->PrintInputFilenames = true;
   }
 
-  if (Arg *A = Args.getLastArg(options::OPT_pg))
+  if (Arg *A = Args.getLastArg(options::OPT_p, options::OPT_pg))
     if (FPKeepKind == CodeGenOptions::FramePointerKind::None &&
         !Args.hasArg(options::OPT_mfentry))
       D.Diag(diag::err_drv_argument_not_allowed_with) << "-fomit-frame-pointer"
Index: clang/lib/CodeGen/CodeGenFunction.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenFunction.cpp
+++ clang/lib/CodeGen/CodeGenFunction.cpp
@@ -1043,7 +1043,8 @@
   // inlining, we just add an attribute to insert a mcount call in backend.
   // The attribute "counting-function" is set to mcount function name which is
   // architecture dependent.
-  if (CGM.getCodeGenOpts().InstrumentForProfiling) {
+  if (CGM.getCodeGenOpts().InstrumentForProfiling ||
+      CGM.getCodeGenOpts().InstrumentForProfilingGraph) {
     // Calls to fentry/mcount should not be generated if function has
     // the no_instrument_function attribute.
     if (!CurFuncDecl || !CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>()) {
Index: clang/lib/CodeGen/BackendUtil.cpp
===================================================================
--- clang/lib/CodeGen/BackendUtil.cpp
+++ clang/lib/CodeGen/BackendUtil.cpp
@@ -923,7 +923,8 @@
     if (CodeGenOpts.InstrumentFunctions ||
         CodeGenOpts.InstrumentFunctionEntryBare ||
         CodeGenOpts.InstrumentFunctionsAfterInlining ||
-        CodeGenOpts.InstrumentForProfiling) {
+        CodeGenOpts.InstrumentForProfiling ||
+        CodeGenOpts.InstrumentForProfilingGraph) {
       PB.registerPipelineStartEPCallback(
           [](ModulePassManager &MPM, OptimizationLevel Level) {
             MPM.addPass(createModuleToFunctionPassAdaptor(
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -4094,8 +4094,10 @@
   MarshallingInfoFlag<DiagnosticOpts<"PedanticErrors">>;
 def pedantic : Flag<["-", "--"], "pedantic">, Group<pedantic_Group>, Flags<[CC1Option,FlangOption,FC1Option]>,
   HelpText<"Warn on language extensions">, MarshallingInfoFlag<DiagnosticOpts<"Pedantic">>;
-def pg : Flag<["-"], "pg">, HelpText<"Enable mcount instrumentation">, Flags<[CC1Option]>,
+def p : Flag<["-"], "p">, HelpText<"Enable mcount instrumentation">, Flags<[CC1Option]>,
   MarshallingInfoFlag<CodeGenOpts<"InstrumentForProfiling">>;
+def pg : Flag<["-"], "pg">, HelpText<"Enable mcount instrumentation">, Flags<[CC1Option]>,
+  MarshallingInfoFlag<CodeGenOpts<"InstrumentForProfilingGraph">>;
 def pipe : Flag<["-", "--"], "pipe">,
   HelpText<"Use pipes between commands, when possible">;
 def prebind__all__twolevel__modules : Flag<["-"], "prebind_all_twolevel_modules">;
@@ -4140,7 +4142,6 @@
   LangOpts<"POSIXThreads">, DefaultFalse,
   PosFlag<SetTrue, [], "Support POSIX threads in generated code">,
   NegFlag<SetFalse>, BothFlags<[CC1Option]>>;
-def p : Flag<["-"], "p">;
 def pie : Flag<["-"], "pie">, Group<Link_Group>;
 def static_pie : Flag<["-"], "static-pie">, Group<Link_Group>;
 def read__only__relocs : Separate<["-"], "read_only_relocs">;
Index: clang/include/clang/Basic/CodeGenOptions.def
===================================================================
--- clang/include/clang/Basic/CodeGenOptions.def
+++ clang/include/clang/Basic/CodeGenOptions.def
@@ -150,7 +150,8 @@
                            ///< generates a 'patchable-function' attribute.
 
 CODEGENOPT(JMCInstrument, 1, 0) ///< Set when -fjmc is enabled.
-CODEGENOPT(InstrumentForProfiling , 1, 0) ///< Set when -pg is enabled.
+CODEGENOPT(InstrumentForProfiling , 1, 0) ///< Set when -p is enabled.
+CODEGENOPT(InstrumentForProfilingGraph , 1, 0) ///< Set when -pg is enabled.
 CODEGENOPT(CallFEntry , 1, 0) ///< Set when -mfentry is enabled.
 CODEGENOPT(MNopMCount , 1, 0) ///< Set when -mnop-mcount is enabled.
 CODEGENOPT(RecordMCount , 1, 0) ///< Set when -mrecord-mcount is enabled.


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