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[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
This commit is contained in:
Teresa Johnson 2019-12-26 09:31:43 -08:00
parent cc14de88da
commit 9c2eb220ed
10 changed files with 55 additions and 17 deletions
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11
clang/test/CodeGenCXX/vcall-visibility-metadata.cpp
View File

@ -1,6 +1,9 @@
// 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

14
llvm/include/llvm/IR/ModuleSummaryIndex.h
View File

@ -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);

8
llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
View File

@ -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));
}

1
llvm/lib/AsmParser/LLLexer.cpp
View File

@ -788,6 +788,7 @@ lltok::Kind LLLexer::LexIdentifier() {
KEYWORD(sizeM1);
KEYWORD(bitMask);
KEYWORD(inlineBits);
KEYWORD(vcall_visibility);
KEYWORD(wpdResolutions);
KEYWORD(wpdRes);
KEYWORD(indir);

8
llvm/lib/AsmParser/LLParser.cpp
View File

@ -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");
}

1
llvm/lib/AsmParser/LLToken.h
View File

@ -421,6 +421,7 @@ enum Kind {
kw_sizeM1,
kw_bitMask,
kw_inlineBits,
kw_vcall_visibility,
kw_wpdResolutions,
kw_wpdRes,
kw_indir,

13
llvm/lib/Bitcode/Reader/BitcodeReader.cpp
View File

@ -985,9 +985,10 @@ static GlobalValueSummary::GVFlags getDecodedGVSummaryFlags(uint64_t RawFlags,
// Decode the flags for GlobalVariable in the summary
static GlobalVarSummary::GVarFlags getDecodedGVarFlags(uint64_t RawFlags) {
return GlobalVarSummary::GVarFlags((RawFlags & 0x1) ? true : false,
(RawFlags & 0x2) ? true : false,
(RawFlags & 0x4) ? true : false);
return GlobalVarSummary::GVarFlags(
(RawFlags & 0x1) ? true : false, (RawFlags & 0x2) ? true : false,
(RawFlags & 0x4) ? true : false,
(GlobalObject::VCallVisibility)(RawFlags >> 3));
}
static GlobalValue::VisibilityTypes getDecodedVisibility(unsigned Val) {
@ -5969,7 +5970,8 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
unsigned RefArrayStart = 2;
GlobalVarSummary::GVarFlags GVF(/* ReadOnly */ false,
/* WriteOnly */ false,
/* Constant */ false);
/* Constant */ false,
GlobalObject::VCallVisibilityPublic);
auto Flags = getDecodedGVSummaryFlags(RawFlags, Version);
if (Version >= 5) {
GVF = getDecodedGVarFlags(Record[2]);
@ -6106,7 +6108,8 @@ Error ModuleSummaryIndexBitcodeReader::parseEntireSummary(unsigned ID) {
unsigned RefArrayStart = 3;
GlobalVarSummary::GVarFlags GVF(/* ReadOnly */ false,
/* WriteOnly */ false,
/* Constant */ false);
/* Constant */ false,
GlobalObject::VCallVisibilityPublic);
auto Flags = getDecodedGVSummaryFlags(RawFlags, Version);
if (Version >= 5) {
GVF = getDecodedGVarFlags(Record[3]);

4
llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
View File

@ -1028,8 +1028,8 @@ static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
}
static uint64_t getEncodedGVarFlags(GlobalVarSummary::GVarFlags Flags) {
uint64_t RawFlags =
Flags.MaybeReadOnly | (Flags.MaybeWriteOnly << 1) | (Flags.Constant << 2);
uint64_t RawFlags = Flags.MaybeReadOnly | (Flags.MaybeWriteOnly << 1) |
(Flags.Constant << 2) | Flags.VCallVisibility << 3;
return RawFlags;
}

8
llvm/lib/IR/AsmWriter.cpp
View File

@ -2900,11 +2900,15 @@ void AssemblyWriter::printAliasSummary(const AliasSummary *AS) {
}
void AssemblyWriter::printGlobalVarSummary(const GlobalVarSummary *GS) {
auto VTableFuncs = GS->vTableFuncs();
Out << ", varFlags: (readonly: " << GS->VarFlags.MaybeReadOnly << ", "
<< "writeonly: " << GS->VarFlags.MaybeWriteOnly << ", "
<< "constant: " << GS->VarFlags.Constant << ")";
<< "constant: " << GS->VarFlags.Constant;
if (!VTableFuncs.empty())
Out << ", "
<< "vcall_visibility: " << GS->VarFlags.VCallVisibility;
Out << ")";
auto VTableFuncs = GS->vTableFuncs();
if (!VTableFuncs.empty()) {
Out << ", vTableFuncs: (";
FieldSeparator FS;

4
llvm/test/Assembler/thinlto-vtable-summary.ll
View File

@ -29,9 +29,9 @@ declare i32 @_ZN1C1fEi(%struct.C*, i32)
^0 = module: (path: "<stdin>", hash: (0, 0, 0, 0, 0))
^1 = gv: (name: "_ZN1A1nEi") ; guid = 1621563287929432257
^2 = gv: (name: "_ZTV1B", summaries: (variable: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), varFlags: (readonly: 0, writeonly: 0, constant: 0), vTableFuncs: ((virtFunc: ^3, offset: 16), (virtFunc: ^1, offset: 24)), refs: (^3, ^1)))) ; guid = 5283576821522790367
^2 = gv: (name: "_ZTV1B", summaries: (variable: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), varFlags: (readonly: 0, writeonly: 0, constant: 0, vcall_visibility: 0), vTableFuncs: ((virtFunc: ^3, offset: 16), (virtFunc: ^1, offset: 24)), refs: (^3, ^1)))) ; guid = 5283576821522790367
^3 = gv: (name: "_ZN1B1fEi") ; guid = 7162046368816414394
^4 = gv: (name: "_ZTV1C", summaries: (variable: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), varFlags: (readonly: 0, writeonly: 0, constant: 0), vTableFuncs: ((virtFunc: ^5, offset: 16), (virtFunc: ^1, offset: 24)), refs: (^1, ^5)))) ; guid = 13624023785555846296
^4 = gv: (name: "_ZTV1C", summaries: (variable: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), varFlags: (readonly: 0, writeonly: 0, constant: 0, vcall_visibility: 0), vTableFuncs: ((virtFunc: ^5, offset: 16), (virtFunc: ^1, offset: 24)), refs: (^1, ^5)))) ; guid = 13624023785555846296
^5 = gv: (name: "_ZN1C1fEi") ; guid = 14876272565662207556
^6 = typeidCompatibleVTable: (name: "_ZTS1A", summary: ((offset: 16, ^2), (offset: 16, ^4))) ; guid = 7004155349499253778
^7 = typeidCompatibleVTable: (name: "_ZTS1B", summary: ((offset: 16, ^2))) ; guid = 6203814149063363976