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[LTO][ThinLTO] Use the linker resolutions to mark global values as dso_local. 

Now that we have a way to mark GlobalValues as local we can use the symbol
resolutions that the linker plugin provides as part of lto/thinlto link
step to refine the compilers view on what symbols will end up being local.

Differential Revision: https://reviews.llvm.org/D35702

llvm-svn: 317374
This commit is contained in:
Sean Fertile 2017-11-03 21:45:55 +00:00
parent 3fc9188fa8
commit 36528c2a9b
19 changed files with 115 additions and 37 deletions
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12
llvm/include/llvm/IR/ModuleSummaryIndex.h
View File

@ -148,11 +148,15 @@ public:
/// In combined summary, indicate that the global value is live.
unsigned Live : 1;
/// Indicates that the linker resolved the symbol to a definition from
/// within the same linkage unit.
unsigned DSOLocal : 1;
/// Convenience Constructors
explicit GVFlags(GlobalValue::LinkageTypes Linkage,
bool NotEligibleToImport, bool Live)
bool NotEligibleToImport, bool Live, bool IsLocal)
: Linkage(Linkage), NotEligibleToImport(NotEligibleToImport),
Live(Live) {}
Live(Live), DSOLocal(IsLocal) {}
};
private:
@ -229,6 +233,10 @@ public:
void setLive(bool Live) { Flags.Live = Live; }
void setDSOLocal(bool Local) { Flags.DSOLocal = Local; }
bool isDSOLocal() const { return Flags.DSOLocal; }
/// Flag that this global value cannot be imported.
void setNotEligibleToImport() { Flags.NotEligibleToImport = true; }

8
llvm/include/llvm/IR/ModuleSummaryIndexYAML.h
View File

@ -135,7 +135,7 @@ template <> struct MappingTraits<TypeIdSummary> {
struct FunctionSummaryYaml {
unsigned Linkage;
bool NotEligibleToImport, Live;
bool NotEligibleToImport, Live, IsLocal;
std::vector<uint64_t> TypeTests;
std::vector<FunctionSummary::VFuncId> TypeTestAssumeVCalls,
TypeCheckedLoadVCalls;
@ -177,6 +177,7 @@ template <> struct MappingTraits<FunctionSummaryYaml> {
io.mapOptional("Linkage", summary.Linkage);
io.mapOptional("NotEligibleToImport", summary.NotEligibleToImport);
io.mapOptional("Live", summary.Live);
io.mapOptional("Local", summary.IsLocal);
io.mapOptional("TypeTests", summary.TypeTests);
io.mapOptional("TypeTestAssumeVCalls", summary.TypeTestAssumeVCalls);
io.mapOptional("TypeCheckedLoadVCalls", summary.TypeCheckedLoadVCalls);
@ -211,7 +212,7 @@ template <> struct CustomMappingTraits<GlobalValueSummaryMapTy> {
Elem.SummaryList.push_back(llvm::make_unique<FunctionSummary>(
GlobalValueSummary::GVFlags(
static_cast<GlobalValue::LinkageTypes>(FSum.Linkage),
FSum.NotEligibleToImport, FSum.Live),
FSum.NotEligibleToImport, FSum.Live, FSum.IsLocal),
0, FunctionSummary::FFlags{}, ArrayRef<ValueInfo>{},
ArrayRef<FunctionSummary::EdgeTy>{}, std::move(FSum.TypeTests),
std::move(FSum.TypeTestAssumeVCalls),
@ -228,7 +229,8 @@ template <> struct CustomMappingTraits<GlobalValueSummaryMapTy> {
FSums.push_back(FunctionSummaryYaml{
FSum->flags().Linkage,
static_cast<bool>(FSum->flags().NotEligibleToImport),
static_cast<bool>(FSum->flags().Live), FSum->type_tests(),
static_cast<bool>(FSum->flags().Live),
static_cast<bool>(FSum->flags().DSOLocal), FSum->type_tests(),
FSum->type_test_assume_vcalls(), FSum->type_checked_load_vcalls(),
FSum->type_test_assume_const_vcalls(),
FSum->type_checked_load_const_vcalls()});

9
llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
View File

@ -303,7 +303,7 @@ computeFunctionSummary(ModuleSummaryIndex &Index, const Module &M,
// FIXME: refactor this to use the same code that inliner is using.
F.isVarArg();
GlobalValueSummary::GVFlags Flags(F.getLinkage(), NotEligibleForImport,
/* Live = */ false);
/* Live = */ false, F.isDSOLocal());
FunctionSummary::FFlags FunFlags{
F.hasFnAttribute(Attribute::ReadNone),
F.hasFnAttribute(Attribute::ReadOnly),
@ -329,7 +329,7 @@ computeVariableSummary(ModuleSummaryIndex &Index, const GlobalVariable &V,
findRefEdges(Index, &V, RefEdges, Visited);
bool NonRenamableLocal = isNonRenamableLocal(V);
GlobalValueSummary::GVFlags Flags(V.getLinkage(), NonRenamableLocal,
/* Live = */ false);
/* Live = */ false, V.isDSOLocal());
auto GVarSummary =
llvm::make_unique<GlobalVarSummary>(Flags, RefEdges.takeVector());
if (NonRenamableLocal)
@ -342,7 +342,7 @@ computeAliasSummary(ModuleSummaryIndex &Index, const GlobalAlias &A,
DenseSet<GlobalValue::GUID> &CantBePromoted) {
bool NonRenamableLocal = isNonRenamableLocal(A);
GlobalValueSummary::GVFlags Flags(A.getLinkage(), NonRenamableLocal,
/* Live = */ false);
/* Live = */ false, A.isDSOLocal());
auto AS = llvm::make_unique<AliasSummary>(Flags);
auto *Aliasee = A.getBaseObject();
auto *AliaseeSummary = Index.getGlobalValueSummary(*Aliasee);
@ -410,7 +410,8 @@ ModuleSummaryIndex llvm::buildModuleSummaryIndex(
assert(GV->isDeclaration() && "Def in module asm already has definition");
GlobalValueSummary::GVFlags GVFlags(GlobalValue::InternalLinkage,
/* NotEligibleToImport = */ true,
/* Live = */ true);
/* Live = */ true,
/* Local */ GV->isDSOLocal());
CantBePromoted.insert(GlobalValue::getGUID(Name));
// Create the appropriate summary type.
if (Function *F = dyn_cast<Function>(GV)) {

4
llvm/lib/Bitcode/Reader/BitcodeReader.cpp
View File

@ -889,7 +889,9 @@ static GlobalValueSummary::GVFlags getDecodedGVSummaryFlags(uint64_t RawFlags,
// to work correctly on earlier versions, we must conservatively treat all
// values as live.
bool Live = (RawFlags & 0x2) || Version < 3;
return GlobalValueSummary::GVFlags(Linkage, NotEligibleToImport, Live);
bool Local = (RawFlags & 0x4);
return GlobalValueSummary::GVFlags(Linkage, NotEligibleToImport, Live, Local);
}
static GlobalValue::VisibilityTypes getDecodedVisibility(unsigned Val) {

2
llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
View File

@ -955,6 +955,8 @@ static uint64_t getEncodedGVSummaryFlags(GlobalValueSummary::GVFlags Flags) {
RawFlags |= Flags.NotEligibleToImport; // bool
RawFlags |= (Flags.Live << 1);
RawFlags |= (Flags.DSOLocal << 2);
// Linkage don't need to be remapped at that time for the summary. Any future
// change to the getEncodedLinkage() function will need to be taken into
// account here as well.

21
llvm/lib/LTO/LTO.cpp
View File

@ -630,6 +630,9 @@ LTO::addRegularLTO(BitcodeModule BM, ArrayRef<InputFile::Symbol> Syms,
NonPrevailingComdats.insert(GV->getComdat());
cast<GlobalObject>(GV)->setComdat(nullptr);
}
// Set the 'local' flag based on the linker resolution for this symbol.
GV->setDSOLocal(Res.FinalDefinitionInLinkageUnit);
}
// Common resolution: collect the maximum size/alignment over all commons.
// We also record if we see an instance of a common as prevailing, so that
@ -643,7 +646,6 @@ LTO::addRegularLTO(BitcodeModule BM, ArrayRef<InputFile::Symbol> Syms,
CommonRes.Prevailing |= Res.Prevailing;
}
// FIXME: use proposed local attribute for FinalDefinitionInLinkageUnit.
}
if (!M.getComdatSymbolTable().empty())
for (GlobalValue &GV : M.global_values())
@ -698,10 +700,10 @@ Error LTO::addThinLTO(BitcodeModule BM, ArrayRef<InputFile::Symbol> Syms,
assert(ResI != ResE);
SymbolResolution Res = *ResI++;
if (Res.Prevailing) {
if (!Sym.getIRName().empty()) {
auto GUID = GlobalValue::getGUID(GlobalValue::getGlobalIdentifier(
Sym.getIRName(), GlobalValue::ExternalLinkage, ""));
if (!Sym.getIRName().empty()) {
auto GUID = GlobalValue::getGUID(GlobalValue::getGlobalIdentifier(
Sym.getIRName(), GlobalValue::ExternalLinkage, ""));
if (Res.Prevailing) {
ThinLTO.PrevailingModuleForGUID[GUID] = BM.getModuleIdentifier();
// For linker redefined symbols (via --wrap or --defsym) we want to
@ -713,6 +715,15 @@ Error LTO::addThinLTO(BitcodeModule BM, ArrayRef<InputFile::Symbol> Syms,
GUID, BM.getModuleIdentifier()))
S->setLinkage(GlobalValue::WeakAnyLinkage);
}
// If the linker resolved the symbol to a local definition then mark it
// as local in the summary for the module we are adding.
if (Res.FinalDefinitionInLinkageUnit) {
if (auto S = ThinLTO.CombinedIndex.findSummaryInModule(
GUID, BM.getModuleIdentifier())) {
S->setDSOLocal(true);
}
}
}
}

17
llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
View File

@ -203,6 +203,23 @@ FunctionImportGlobalProcessing::getLinkage(const GlobalValue *SGV,
}
void FunctionImportGlobalProcessing::processGlobalForThinLTO(GlobalValue &GV) {
// Check the summaries to see if the symbol gets resolved to a known local
// definition.
if (GV.hasName()) {
ValueInfo VI = ImportIndex.getValueInfo(GV.getGUID());
if (VI) {
// Need to check all summaries are local in case of hash collisions.
bool IsLocal = VI.getSummaryList().size() &&
llvm::all_of(VI.getSummaryList(),
[](const std::unique_ptr<GlobalValueSummary> &Summary) {
return Summary->isDSOLocal();
});
if (IsLocal)
GV.setDSOLocal(true);
}
}
bool DoPromote = false;
if (GV.hasLocalLinkage() &&
((DoPromote = shouldPromoteLocalToGlobal(&GV)) || isPerformingImport())) {

22
llvm/test/Bitcode/thinlto-summary-local-5.0.ll Normal file
View File

@ -0,0 +1,22 @@
; Bitcode compatibility test for dso_local flag in thin-lto summaries.
; Checks that older bitcode summaries without the dso_local op are still
; properly parsed and don't set GlobalValues as dso_local.
; RUN: llvm-dis < %s.bc | FileCheck %s
; RUN: llvm-bcanalyzer -dump %s.bc | FileCheck %s --check-prefix=BCAN
define void @foo() {
;CHECK-DAG:define void @foo()
ret void
}
@bar = global i32 0
;CHECK-DAG: @bar = global i32 0
@baz = alias i32, i32* @bar
;CHECK-DAG: @bar = global i32 0
;BCAN: <SOURCE_FILENAME
;BCAN-NEXT: <GLOBALVAR {{.*}} op7=0/>
;BCAN-NEXT: <FUNCTION {{.*}} op16=0/>
;BCAN-NEXT: <ALIAS {{.*}} op9=0/>

BIN
llvm/test/Bitcode/thinlto-summary-local-5.0.ll.bc Normal file
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Binary file not shown.

2
llvm/test/LTO/Resolution/X86/comdat-mixed-lto.ll
View File

@ -17,7 +17,7 @@
; would clash with the copy from this module.
; RUN: llvm-dis %t3.0.0.preopt.bc -o - | FileCheck %s
; CHECK: define internal void @__cxx_global_var_init() section ".text.startup" {
; CHECK: define available_externally void @testglobfunc() section ".text.startup" {
; CHECK: define available_externally dso_local void @testglobfunc() section ".text.startup" {
; ModuleID = 'comdat-mixed-lto.o'
source_filename = "comdat-mixed-lto.cpp"

4
llvm/test/LTO/Resolution/X86/comdat.ll
View File

@ -70,14 +70,14 @@ bb11:
; CHECK-DAG: @a23 = alias i32 (i8*), i32 (i8*)* @f1.2{{$}}
; CHECK-DAG: @a24 = alias i16, bitcast (i32 (i8*)* @f1.2 to i16*)
; CHECK: define weak_odr i32 @f1(i8*) comdat($c1) {
; CHECK: define weak_odr dso_local i32 @f1(i8*) comdat($c1) {
; CHECK-NEXT: bb10:
; CHECK-NEXT: br label %bb11{{$}}
; CHECK: bb11:
; CHECK-NEXT: ret i32 42
; CHECK-NEXT: }
; CHECK: define internal i32 @f1.2(i8* %this) comdat($c2) {
; CHECK: define internal dso_local i32 @f1.2(i8* %this) comdat($c2) {
; CHECK-NEXT: bb20:
; CHECK-NEXT: store i8* %this, i8** null
; CHECK-NEXT: br label %bb21

2
llvm/test/LTO/Resolution/X86/commons.ll
View File

@ -4,7 +4,7 @@
; RUN: llvm-dis -o - %t.out.0.0.preopt.bc | FileCheck %s
; A strong definition should override the common
; CHECK: @x = global i32 42, align 4
; CHECK: @x = dso_local global i32 42, align 4
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

30
llvm/test/ThinLTO/X86/deadstrip.ll
View File

@ -18,8 +18,8 @@
; RUN: -r %t2.bc,_boo,pl \
; RUN: -r %t2.bc,_dead_func,pl \
; RUN: -r %t2.bc,_another_dead_func,pl
; RUN: llvm-dis < %t.out.0.3.import.bc | FileCheck %s
; RUN: llvm-dis < %t.out.1.3.import.bc | FileCheck %s --check-prefix=CHECK2
; RUN: llvm-dis < %t.out.0.3.import.bc | FileCheck %s --check-prefix=LTO2
; RUN: llvm-dis < %t.out.1.3.import.bc | FileCheck %s --check-prefix=LTO2-CHECK2
; RUN: llvm-nm %t.out.1 | FileCheck %s --check-prefix=CHECK2-NM
; RUN: llvm-bcanalyzer -dump %t.out.index.bc | FileCheck %s --check-prefix=COMBINED
@ -27,14 +27,14 @@
; COMBINED-DAG: <COMBINED {{.*}} op2=55
; Live, Internal
; COMBINED-DAG: <COMBINED {{.*}} op2=39
; Live, External
; COMBINED-DAG: <COMBINED {{.*}} op2=32
; COMBINED-DAG: <COMBINED {{.*}} op2=32
; COMBINED-DAG: <COMBINED {{.*}} op2=32
; (Dead)
; COMBINED-DAG: <COMBINED {{.*}} op2=0
; COMBINED-DAG: <COMBINED {{.*}} op2=0
; COMBINED-DAG: <COMBINED {{.*}} op2=0
; Live, Local, External
; COMBINED-DAG: <COMBINED {{.*}} op2=96
; COMBINED-DAG: <COMBINED {{.*}} op2=96
; COMBINED-DAG: <COMBINED {{.*}} op2=96
; Local, (Dead)
; COMBINED-DAG: <COMBINED {{.*}} op2=64
; COMBINED-DAG: <COMBINED {{.*}} op2=64
; COMBINED-DAG: <COMBINED {{.*}} op2=64
; Dead-stripping on the index allows to internalize these,
; and limit the import of @baz thanks to early pruning.
@ -45,10 +45,18 @@
; CHECK: define internal void @bar_internal()
; CHECK: define internal void @dead_func() {
; CHECK-NOT: available_externally {{.*}} @baz()
; LTO2-NOT: available_externally {{.*}} @baz()
; LTO2: @llvm.global_ctors =
; LTO2: define internal void @_GLOBAL__I_a()
; LTO2: define internal dso_local void @bar() {
; LTO2: define internal void @bar_internal()
; LTO2: define internal dso_local void @dead_func() {
; LTO2-NOT: available_externally {{.*}} @baz()
; Make sure we didn't internalize @boo, which is reachable via
; llvm.global_ctors
; CHECK2: define void @boo()
; LTO2-CHECK2: define dso_local void @boo()
; We should have eventually removed @baz since it was internalized and unused
; CHECK2-NM-NOT: _baz
@ -80,7 +88,7 @@
; We can't internalize @dead_func because of the use in the regular LTO
; partition.
; CHECK-NOTDEAD: define void @dead_func()
; CHECK-NOTDEAD: define dso_local void @dead_func()
; We also can't eliminate @baz because it is in the regular LTO partition
; and called from @dead_func.
; CHECK-NM-NOTDEAD: T _baz

4
llvm/test/ThinLTO/X86/funcimport2.ll
View File

@ -7,7 +7,7 @@
; RUN: -r=%t2.bc,_main,plx \
; RUN: -r=%t2.bc,_foo,l
; RUN: llvm-dis %t.o.1.3.import.bc -o - | FileCheck %s
; CHECK: define available_externally void @foo()
; CHECK: define available_externally dso_local void @foo()
; We shouldn't do any importing at -O0
; rm -f %t.o.1.3.import.bc
@ -17,7 +17,7 @@
; RUN: -r=%t2.bc,_main,plx \
; RUN: -r=%t2.bc,_foo,l
; RUN: llvm-dis %t.o.1.3.import.bc -o - | FileCheck %s --check-prefix=CHECKO0
; CHECKO0: declare void @foo(...)
; CHECKO0: declare dso_local void @foo(...)
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.11.0"

9
llvm/test/ThinLTO/X86/internalize.ll
View File

@ -1,4 +1,4 @@
;; RUN: opt -module-summary %s -o %t1.bc
; RUN: opt -module-summary %s -o %t1.bc
; RUN: llvm-lto -thinlto-action=thinlink -o %t.index.bc %t1.bc
; RUN: llvm-lto -thinlto-action=internalize -thinlto-index %t.index.bc %t1.bc -o - | llvm-dis -o - | FileCheck %s --check-prefix=REGULAR
; RUN: llvm-lto -thinlto-action=internalize -thinlto-index %t.index.bc %t1.bc -o - --exported-symbol=foo | llvm-dis -o - | FileCheck %s --check-prefix=INTERNALIZE
@ -7,7 +7,7 @@
; RUN: -r=%t1.bc,_foo,pxl \
; RUN: -r=%t1.bc,_bar,pl \
; RUN: -r=%t1.bc,_linkonce_func,pl
; RUN: llvm-dis < %t.o.0.2.internalize.bc | FileCheck %s --check-prefix=INTERNALIZE
; RUN: llvm-dis < %t.o.0.2.internalize.bc | FileCheck %s --check-prefix=INTERNALIZE2
; REGULAR: define void @foo
@ -16,6 +16,9 @@
; INTERNALIZE: define void @foo
; INTERNALIZE: define internal void @bar
; INTERNALIZE: define internal void @linkonce_func()
; INTERNALIZE2: define dso_local void @foo
; INTERNALIZE2: define internal dso_local void @bar
; INTERNALIZE2: define internal dso_local void @linkonce_func()
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.11.0"
@ -29,4 +32,4 @@ define void @bar() {
}
define linkonce void @linkonce_func() {
ret void
}
}

2
llvm/test/ThinLTO/X86/reference_non_importable.ll
View File

@ -22,7 +22,7 @@ target triple = "x86_64-apple-macosx10.11.0"
; We want foo to be imported in the main module!
; RUN: llvm-dis < %t.o.1.3.import.bc | FileCheck %s --check-prefix=IMPORT
; IMPORT: define available_externally i8** @foo()
; IMPORT: define available_externally dso_local i8** @foo()
define i8 **@foo() {
ret i8 **@b
}

1
llvm/test/Transforms/LowerTypeTests/import-unsat.ll
View File

@ -7,6 +7,7 @@
; SUMMARY-NEXT: - Linkage: 0
; SUMMARY-NEXT: NotEligibleToImport: false
; SUMMARY-NEXT: Live: true
; SUMMARY-NEXT: Local: false
; SUMMARY-NEXT: TypeTests: [ 123 ]
; SUMMARY-NEXT: TypeIdMap:
; SUMMARY-NEXT: typeid1:

2
llvm/test/Transforms/PGOProfile/thinlto_samplepgo_icp2.ll
View File

@ -22,7 +22,7 @@
; RUN: llvm-nm %t3.2 | FileCheck %s --check-prefix=NM
; NM: _ZL3barv
; RUN: llvm-dis < %t3.2.2.internalize.bc | FileCheck %s --check-prefix=INTERNALIZE
; INTERNALIZE: define void @_ZL3barv
; INTERNALIZE: define dso_local void @_ZL3barv
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

1
llvm/test/Transforms/WholeProgramDevirt/import-indir.ll
View File

@ -7,6 +7,7 @@
; SUMMARY-NEXT: - Linkage: 0
; SUMMARY-NEXT: NotEligibleToImport: false
; SUMMARY-NEXT: Live: true
; SUMMARY-NEXT: Local: false
; SUMMARY-NEXT: TypeTestAssumeVCalls:
; SUMMARY-NEXT: - GUID: 123
; SUMMARY-NEXT: Offset: 0