Commit 9c2eb220 authored by Teresa Johnson's avatar Teresa Johnson
Browse files

[ThinLTO] Summarize vcall_visibility metadata 

Summary:
Second patch in series to support Safe Whole Program Devirtualization
Enablement, see RFC here:
http://lists.llvm.org/pipermail/llvm-dev/2019-December/137543.html

Summarize vcall_visibility metadata in ThinLTO global variable summary.

Depends on D71907.

Reviewers: pcc, evgeny777, steven_wu

Subscribers: mehdi_amini, Prazek, inglorion, hiraditya, dexonsmith, arphaman, ostannard, llvm-commits, cfe-commits, davidxl

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D71911
parent cc14de88

clang/test/CodeGenCXX/vcall-visibility-metadata.cpp

+11 −0
Original line number Diff line number Diff line 
// RUN: %clang_cc1 -flto -flto-unit -triple x86_64-unknown-linux -emit-llvm -fvirtual-function-elimination -fwhole-program-vtables -o - %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-VFE

// RUN: %clang_cc1 -flto -flto-unit -triple x86_64-unknown-linux -emit-llvm -fwhole-program-vtables -o - %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-NOVFE



// Check that in ThinLTO we also get vcall_visibility summary entries in the bitcode

// RUN: %clang_cc1 -flto=thin -flto-unit -triple x86_64-unknown-linux -emit-llvm-bc -fwhole-program-vtables -o - %s | llvm-dis -o - | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-NOVFE --check-prefix=CHECK-SUMMARY





// Anonymous namespace.

namespace {
@@ -88,3 +91,11 @@ void *construct_G() { 
// CHECK-DAG: [[VIS_TU]] = !{i64 2}

// CHECK-VFE-DAG: !{i32 1, !"Virtual Function Elim", i32 1}

// CHECK-NOVFE-DAG: !{i32 1, !"Virtual Function Elim", i32 0}



// CHECK-SUMMARY-DAG: gv: (name: "_ZTV1B", {{.*}} vcall_visibility: 1

// CHECK-SUMMARY-DAG: gv: (name: "_ZTVN12_GLOBAL__N_11FE", {{.*}} vcall_visibility: 0

// CHECK-SUMMARY-DAG: gv: (name: "_ZTV1D", {{.*}} vcall_visibility: 0

// CHECK-SUMMARY-DAG: gv: (name: "_ZTV1C", {{.*}} vcall_visibility: 0

// CHECK-SUMMARY-DAG: gv: (name: "_ZTV1E", {{.*}} vcall_visibility: 0

// CHECK-SUMMARY-DAG: gv: (name: "_ZTVN12_GLOBAL__N_11AE", {{.*}} vcall_visibility: 2

// CHECK-SUMMARY-DAG: gv: (name: "_ZTVN12_GLOBAL__N_11GE", {{.*}} vcall_visibility: 1

llvm/include/llvm/IR/ModuleSummaryIndex.h

+12 −2
Original line number Diff line number Diff line
@@ -757,9 +757,10 @@ private: 


public:

  struct GVarFlags {

    GVarFlags(bool ReadOnly, bool WriteOnly, bool Constant)

    GVarFlags(bool ReadOnly, bool WriteOnly, bool Constant,

              GlobalObject::VCallVisibility Vis)

        : MaybeReadOnly(ReadOnly), MaybeWriteOnly(WriteOnly),

          Constant(Constant) {}

          Constant(Constant), VCallVisibility(Vis) {}



    // If true indicates that this global variable might be accessed

    // purely by non-volatile load instructions. This in turn means
@@ -780,6 +781,9 @@ public: 
    // opportunity to make some extra optimizations. Readonly constants

    // are also internalized.

    unsigned Constant : 1;

    // Set from metadata on vtable definitions during the module summary

    // analysis.

    unsigned VCallVisibility : 2;

  } VarFlags;



  GlobalVarSummary(GVFlags Flags, GVarFlags VarFlags,
@@ -798,6 +802,12 @@ public: 
  bool maybeReadOnly() const { return VarFlags.MaybeReadOnly; }

  bool maybeWriteOnly() const { return VarFlags.MaybeWriteOnly; }

  bool isConstant() const { return VarFlags.Constant; }

  void setVCallVisibility(GlobalObject::VCallVisibility Vis) {

    VarFlags.VCallVisibility = Vis;

  }

  GlobalObject::VCallVisibility getVCallVisibility() const {

    return (GlobalObject::VCallVisibility)VarFlags.VCallVisibility;

  }



  void setVTableFuncs(VTableFuncList Funcs) {

    assert(!VTableFuncs);

llvm/lib/Analysis/ModuleSummaryAnalysis.cpp

+5 −3
Original line number Diff line number Diff line
@@ -600,8 +600,9 @@ static void computeVariableSummary(ModuleSummaryIndex &Index, 
      !V.hasComdat() && !V.hasAppendingLinkage() && !V.isInterposable() &&

      !V.hasAvailableExternallyLinkage() && !V.hasDLLExportStorageClass();

  bool Constant = V.isConstant();

  GlobalVarSummary::GVarFlags VarFlags(

      CanBeInternalized, Constant ? false : CanBeInternalized, Constant);

  GlobalVarSummary::GVarFlags VarFlags(CanBeInternalized,

                                       Constant ? false : CanBeInternalized,

                                       Constant, V.getVCallVisibility());

  auto GVarSummary = std::make_unique<GlobalVarSummary>(Flags, VarFlags,

                                                         RefEdges.takeVector());

  if (NonRenamableLocal)
@@ -722,7 +723,8 @@ ModuleSummaryIndex llvm::buildModuleSummaryIndex( 
                std::make_unique<GlobalVarSummary>(

                    GVFlags,

                    GlobalVarSummary::GVarFlags(

                        false, false, cast<GlobalVariable>(GV)->isConstant()),

                        false, false, cast<GlobalVariable>(GV)->isConstant(),

                        GlobalObject::VCallVisibilityPublic),

                    ArrayRef<ValueInfo>{});

            Index.addGlobalValueSummary(*GV, std::move(Summary));

          }

llvm/lib/AsmParser/LLLexer.cpp

+1 −0
Original line number Diff line number Diff line
@@ -788,6 +788,7 @@ lltok::Kind LLLexer::LexIdentifier() { 
  KEYWORD(sizeM1);

  KEYWORD(bitMask);

  KEYWORD(inlineBits);

  KEYWORD(vcall_visibility);

  KEYWORD(wpdResolutions);

  KEYWORD(wpdRes);

  KEYWORD(indir);

llvm/lib/AsmParser/LLParser.cpp

+7 −1
Original line number Diff line number Diff line
@@ -8154,7 +8154,8 @@ bool LLParser::ParseVariableSummary(std::string Name, GlobalValue::GUID GUID, 
      /*Live=*/false, /*IsLocal=*/false, /*CanAutoHide=*/false);

  GlobalVarSummary::GVarFlags GVarFlags(/*ReadOnly*/ false,

                                        /* WriteOnly */ false,

                                        /* Constant */ false);

                                        /* Constant */ false,

                                        GlobalObject::VCallVisibilityPublic);

  std::vector<ValueInfo> Refs;

  VTableFuncList VTableFuncs;

  if (ParseToken(lltok::colon, "expected ':' here") ||
@@ -8861,6 +8862,11 @@ bool LLParser::ParseGVarFlags(GlobalVarSummary::GVarFlags &GVarFlags) { 
        return true;

      GVarFlags.Constant = Flag;

      break;

    case lltok::kw_vcall_visibility:

      if (ParseRest(Flag))

        return true;

      GVarFlags.VCallVisibility = Flag;

      break;

    default:

      return Error(Lex.getLoc(), "expected gvar flag type");

    }