[clang][misexpect] Add support to clang for profitable annotation diagnostics

[paulkirth]

Summary

Add basic plumbing to clang so that diagnostics can be surfaced to users

[paulkirth]

Fix Clang tests and flags

[paulkirth]

Rebase

clang/include/clang/Basic/CodeGenOptions.def

 CODEGENOPT(NoDwarfDirectoryAsm , 1, 0) ///< Set when -fno-dwarf-directory-asm is
                                        ///< enabled.
 CODEGENOPT(NoExecStack       , 1, 0) ///< Set when -Wa,--noexecstack is enabled.
 CODEGENOPT(FatalWarnings     , 1, 0) ///< Set when -Wa,--fatal-warnings is
                                      ///< enabled.
 CODEGENOPT(NoWarn            , 1, 0) ///< Set when -Wa,--no-warn is enabled.
 CODEGENOPT(NoTypeCheck       , 1, 0) ///< Set when -Wa,--no-type-check is enabled.
 CODEGENOPT(MisExpect         , 1, 0) ///< Set when -Wmisexpect is enabled
+CODEGENOPT(MissingAnnotations, 1, 0) ///< Set when suggesting missing perf annotations
 CODEGENOPT(EnableSegmentedStacks , 1, 0) ///< Set when -fsplit-stack is enabled.
 CODEGENOPT(NoInlineLineTables, 1, 0) ///< Whether debug info should contain
                                      ///< inline line tables.
 CODEGENOPT(StackClashProtector, 1, 0) ///< Set when -fstack-clash-protection is enabled.
 CODEGENOPT(NoImplicitFloat   , 1, 0) ///< Set when -mno-implicit-float is enabled.
 CODEGENOPT(NullPointerIsValid , 1, 0) ///< Assume Null pointer deference is defined.
 CODEGENOPT(OpenCLCorrectlyRoundedDivSqrt, 1, 0) ///< -cl-fp32-correctly-rounded-divide-sqrt
 CODEGENOPT(HIPCorrectlyRoundedDivSqrt, 1, 1) ///< -fno-hip-fp32-correctly-rounded-divide-sqrt

clang/include/clang/Driver/Options.td

defm diagnostics_show_hotness : BoolFOption<"diagnostics-show-hotness",
   NegFlag<SetFalse>>;
 def fdiagnostics_hotness_threshold_EQ : Joined<["-"], "fdiagnostics-hotness-threshold=">,
     Group<f_Group>, Flags<[CC1Option]>, MetaVarName<"<value>">,
     HelpText<"Prevent optimization remarks from being output if they do not have at least this profile count. "
     "Use 'auto' to apply the threshold from profile summary">;
 def fdiagnostics_misexpect_tolerance_EQ : Joined<["-"], "fdiagnostics-misexpect-tolerance=">,
     Group<f_Group>, Flags<[CC1Option]>, MetaVarName<"<value>">,
     HelpText<"Prevent misexpect diagnostics from being output if the profile counts are within N% of the expected. ">;
+defm diagnostics_missing_annotations : BoolFOption<"diagnostics-missing-annotations",
+  CodeGenOpts<"MissingAnnotations">, DefaultFalse,
+  PosFlag<SetTrue, [CC1Option], "Enable profile hotness information in diagnostic line">,
+  NegFlag<SetFalse>>;
 defm diagnostics_show_option : BoolFOption<"diagnostics-show-option",
     DiagnosticOpts<"ShowOptionNames">, DefaultTrue,
     NegFlag<SetFalse, [CC1Option]>, PosFlag<SetTrue, [], "Print option name with mappable diagnostics">>;
 defm diagnostics_show_note_include_stack : BoolFOption<"diagnostics-show-note-include-stack",
     DiagnosticOpts<"ShowNoteIncludeStack">, DefaultFalse,
     PosFlag<SetTrue, [], "Display include stacks for diagnostic notes">,
     NegFlag<SetFalse>, BothFlags<[CC1Option]>>;
 def fdiagnostics_format_EQ : Joined<["-"], "fdiagnostics-format=">, Group<f_clang_Group>;

clang/lib/CodeGen/BackendUtil.cpp

if (!Entry.IsFramework &&
          Entry.Group == frontend::IncludeDirGroup::Angled ||
          Entry.Group == frontend::IncludeDirGroup::System))
       Options.MCOptions.IASSearchPaths.push_back(
           Entry.IgnoreSysRoot ? Entry.Path : HSOpts.Sysroot + Entry.Path);
   Options.MCOptions.Argv0 = CodeGenOpts.Argv0;
   Options.MCOptions.CommandLineArgs = CodeGenOpts.CommandLineArgs;
   Options.MCOptions.AsSecureLogFile = CodeGenOpts.AsSecureLogFile;
   Options.MisExpect = CodeGenOpts.MisExpect;
+  Options.MissingAnnotations = CodeGenOpts.MissingAnnotations;
 
   return true;
 }
 
 static std::optional<GCOVOptions>
 getGCOVOptions(const CodeGenOptions &CodeGenOpts, const LangOptions &LangOpts) {
   if (!CodeGenOpts.EmitGcovArcs && !CodeGenOpts.EmitGcovNotes)
     return std::nullopt;

clang/lib/CodeGen/CodeGenAction.cpp

void HandleTranslationUnit(ASTContext &C) override {
       if (OptRecordFile &&
           CodeGenOpts.getProfileUse() != CodeGenOptions::ProfileNone)
         Ctx.setDiagnosticsHotnessRequested(true);
 
       if (CodeGenOpts.MisExpect) {
         Ctx.setMisExpectWarningRequested(true);
       }
 
+      if (CodeGenOpts.MissingAnnotations) {
+        Ctx.setAnnotationDiagsRequested(true);
+      }
+
       if (CodeGenOpts.DiagnosticsMisExpectTolerance) {
         Ctx.setDiagnosticsMisExpectTolerance(
             CodeGenOpts.DiagnosticsMisExpectTolerance);
       }
 
       // Link each LinkModule into our module.
       if (LinkInModules())
         return;

clang/test/Profile/Inputs/missing-annotation.proftext

+bar
+# Func Hash:
[phone]
+# Num Counters:
+2
+# Counter Values:
+200000
+1
+
+fizz
+# Func Hash:
[phone]
+# Num Counters:
+2
+# Counter Values:
+200000
+1
+

clang/test/Profile/missing-annotation.c

+// Test that missing annotation diagnostics are suggested for hot branches
+
+// test diagnostics are issued when profiling data mis-matches annotations
+// RUN: llvm-profdata merge %S/Inputs/missing-annotation.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify=exact -fdiagnostics-missing-annotations -debug-info-kind=line-tables-only -Rpass=missing-annotations
+
+
+// foo-no-diagnostics
+
+int foo(int);
+int baz(int);
+int buzz();
+
+const int inner_loop = 100;
+const int outer_loop = 2000;
+int bar() { 
+  int rando = buzz();
+  int x = 0;
+  if (rando % (outer_loop * inner_loop) == 0) { // exact-remark {{Extremely hot condition. Consider adding  llvm.expect intrinsic}}
+    x = baz(rando);
+  } else {
+    x = foo(50);
+  }
+  return x;
+}
+
+int fizz() {
+  int rando = buzz();
+  int x = 0;
+  if (rando % (outer_loop * inner_loop) == 0) { // exact-remark {{Extremely hot condition. Consider adding  llvm.expect intrinsic}}
+    x = baz(rando);
+  } else {
+    x = foo(50);
+  }
+  return x;
+}
+