replica
/
hanchenye-llvm-project
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Currently lld creates a single section to collect all commons. There is no way 

to separate commons based on file name patterns. The following linker script
construct does not work because commons are allocated before section placement
is done and the only synthesized BssSection that holds all commons has no file
associated with it:
SECTIONS { .common_0 : { *file0.o(COMMON) }}

This patch changes the allocation of commons to create a section per common
symbol and let the section logic do the layout.

Differential revision: https://reviews.llvm.org/D37489

llvm-svn: 312796
This commit is contained in:
Dmitry Mikulin 2017-09-08 16:22:43 +00:00
parent 500c25e5da
commit 1e30f07ce7
15 changed files with 243 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
lld/ELF/LinkerScript.cpp
View File

@ -174,17 +174,17 @@ bool BytesDataCommand::classof(const BaseCommand *C) {
return C->Kind == BytesDataKind;
}
static std::string filename(InputSectionBase *S) {
if (!S->File)
static std::string filename(InputFile *File) {
if (!File)
return "";
if (S->File->ArchiveName.empty())
return S->File->getName();
return (S->File->ArchiveName + "(" + S->File->getName() + ")").str();
if (File->ArchiveName.empty())
return File->getName();
return (File->ArchiveName + "(" + File->getName() + ")").str();
}
bool LinkerScript::shouldKeep(InputSectionBase *S) {
for (InputSectionDescription *ID : Opt.KeptSections) {
std::string Filename = filename(S);
std::string Filename = filename(S->File);
if (ID->FilePat.match(Filename))
for (SectionPattern &P : ID->SectionPatterns)
if (P.SectionPat.match(S->Name))
@ -284,7 +284,7 @@ LinkerScript::computeInputSections(const InputSectionDescription *Cmd) {
if (Sec->Type == SHT_REL || Sec->Type == SHT_RELA)
continue;
std::string Filename = filename(Sec);
std::string Filename = filename(Sec->File);
if (!Cmd->FilePat.match(Filename) ||
Pat.ExcludedFilePat.match(Filename) ||
!Pat.SectionPat.match(Sec->Name))
@ -328,8 +328,8 @@ LinkerScript::computeInputSections(const InputSectionDescription *Cmd) {
void LinkerScript::discard(ArrayRef<InputSectionBase *> V) {
for (InputSectionBase *S : V) {
S->Live = false;
if (S == InX::ShStrTab || S == InX::Common || S == InX::Dynamic ||
S == InX::DynSymTab || S == InX::DynStrTab)
if (S == InX::ShStrTab || S == InX::Dynamic || S == InX::DynSymTab ||
S == InX::DynStrTab)
error("discarding " + S->Name + " section is not allowed");
discard(S->DependentSections);
}
@ -868,7 +868,7 @@ ExprValue LinkerScript::getSymbolValue(const Twine &Loc, StringRef S) {
if (auto *D = dyn_cast<DefinedRegular>(B))
return {D->Section, D->Value, Loc};
if (auto *C = dyn_cast<DefinedCommon>(B))
return {InX::Common, C->Offset, Loc};
return {C->Section, C->Offset, Loc};
}
error(Loc + ": symbol not found: " + S);
return 0;

6
lld/ELF/MapFile.cpp
View File

@ -57,7 +57,7 @@ template <class ELFT> static std::vector<Defined *> getSymbols() {
DR->Section->Live)
V.push_back(DR);
} else if (auto *DC = dyn_cast<DefinedCommon>(B)) {
if (InX::Common)
if (DC->Section)
V.push_back(DC);
}
}
@ -71,8 +71,8 @@ static SymbolMapTy getSectionSyms(ArrayRef<Defined *> Syms) {
for (Defined *S : Syms) {
if (auto *DR = dyn_cast<DefinedRegular>(S))
Ret[DR->Section].push_back(S);
else
Ret[InX::Common].push_back(S);
else if (auto *DC = dyn_cast<DefinedCommon>(S))
Ret[DC->Section].push_back(S);
}
// Sort symbols by address. We want to print out symbols in the

12
lld/ELF/Symbols.cpp
View File

@ -99,11 +99,13 @@ static uint64_t getSymVA(const SymbolBody &Body, int64_t &Addend) {
}
return VA;
}
case SymbolBody::DefinedCommonKind:
case SymbolBody::DefinedCommonKind: {
if (!Config->DefineCommon)
return 0;
return InX::Common->getParent()->Addr + InX::Common->OutSecOff +
cast<DefinedCommon>(Body).Offset;
auto DC = cast<DefinedCommon>(Body);
return DC.Section->getParent()->Addr + DC.Section->OutSecOff +
DC.Offset;
}
case SymbolBody::SharedKind: {
auto &SS = cast<SharedSymbol>(Body);
if (SS.CopyRelSec)
@ -202,9 +204,9 @@ OutputSection *SymbolBody::getOutputSection() const {
return nullptr;
}
if (isa<DefinedCommon>(this)) {
if (auto *S = dyn_cast<DefinedCommon>(this)) {
if (Config->DefineCommon)
return InX::Common->getParent();
return S->Section->getParent();
return nullptr;
}

2
lld/ELF/Symbols.h
View File

@ -27,6 +27,7 @@ namespace elf {
class ArchiveFile;
class BitcodeFile;
class BssSection;
class InputFile;
class LazyObjFile;
template <class ELFT> class ObjFile;
@ -173,6 +174,7 @@ public:
// Computed by the writer.
uint64_t Offset;
uint64_t Size;
BssSection *Section = nullptr;
};
// Regular defined symbols read from object file symbol tables.

45
lld/ELF/SyntheticSections.cpp
View File

@ -54,35 +54,22 @@ uint64_t SyntheticSection::getVA() const {
return 0;
}
template <class ELFT> static std::vector<DefinedCommon *> getCommonSymbols() {
std::vector<DefinedCommon *> V;
for (Symbol *S : Symtab->getSymbols())
if (auto *B = dyn_cast<DefinedCommon>(S->body()))
V.push_back(B);
return V;
}
// Find all common symbols and allocate space for them.
template <class ELFT> InputSection *elf::createCommonSection() {
std::vector<InputSection *> elf::createCommonSections() {
if (!Config->DefineCommon)
return nullptr;
return {};
// Sort the common symbols by alignment as an heuristic to pack them better.
std::vector<DefinedCommon *> Syms = getCommonSymbols<ELFT>();
if (Syms.empty())
return nullptr;
std::vector<InputSection *> Ret;
for (Symbol *S : Symtab->getSymbols()) {
auto *Sym = dyn_cast<DefinedCommon>(S->body());
if (!Sym || !Sym->Live)
continue;
std::stable_sort(Syms.begin(), Syms.end(),
[](const DefinedCommon *A, const DefinedCommon *B) {
return A->Alignment > B->Alignment;
});
// Allocate space for common symbols.
BssSection *Sec = make<BssSection>("COMMON");
for (DefinedCommon *Sym : Syms)
if (Sym->Live)
Sym->Offset = Sec->reserveSpace(Sym->Size, Sym->Alignment);
return Sec;
Sym->Section = make<BssSection>("COMMON");
Sym->Offset = Sym->Section->reserveSpace(Sym->Size, Sym->Alignment);
Sym->Section->File = Sym->getFile();
Ret.push_back(Sym->Section);
}
return Ret;
}
// Returns an LLD version string.
@ -2321,7 +2308,6 @@ InputSection *InX::ARMAttributes;
BssSection *InX::Bss;
BssSection *InX::BssRelRo;
BuildIdSection *InX::BuildId;
InputSection *InX::Common;
SyntheticSection *InX::Dynamic;
StringTableSection *InX::DynStrTab;
SymbolTableBaseSection *InX::DynSymTab;
@ -2349,11 +2335,6 @@ template void PltSection::addEntry<ELF32BE>(SymbolBody &Sym);
template void PltSection::addEntry<ELF64LE>(SymbolBody &Sym);
template void PltSection::addEntry<ELF64BE>(SymbolBody &Sym);
template InputSection *elf::createCommonSection<ELF32LE>();
template InputSection *elf::createCommonSection<ELF32BE>();
template InputSection *elf::createCommonSection<ELF64LE>();
template InputSection *elf::createCommonSection<ELF64BE>();
template MergeInputSection *elf::createCommentSection<ELF32LE>();
template MergeInputSection *elf::createCommentSection<ELF32BE>();
template MergeInputSection *elf::createCommentSection<ELF64LE>();

3
lld/ELF/SyntheticSections.h
View File

@ -740,7 +740,7 @@ private:
size_t Size = 0;
};
template <class ELFT> InputSection *createCommonSection();
std::vector<InputSection *> createCommonSections();
InputSection *createInterpSection();
template <class ELFT> MergeInputSection *createCommentSection();
void decompressAndMergeSections();
@ -754,7 +754,6 @@ struct InX {
static BssSection *Bss;
static BssSection *BssRelRo;
static BuildIdSection *BuildId;
static InputSection *Common;
static SyntheticSection *Dynamic;
static StringTableSection *DynStrTab;
static SymbolTableBaseSection *DynSymTab;

6
lld/ELF/Writer.cpp
View File

@ -299,9 +299,9 @@ template <class ELFT> void Writer<ELFT>::createSyntheticSections() {
Add(InX::BuildId);
}
InX::Common = createCommonSection<ELFT>();
if (InX::Common)
Add(InX::Common);
auto Commons = createCommonSections();
for (InputSection *S : Commons)
Add(S);
InX::Bss = make<BssSection>(".bss");
Add(InX::Bss);

10
lld/test/ELF/common.s
View File

@ -12,13 +12,13 @@
// CHECK-NEXT: ]
// CHECK-NEXT: Address: 0x201000
// CHECK-NEXT: Offset:
// CHECK-NEXT: Size: 22
// CHECK-NEXT: Size: 36
// CHECK-NEXT: Link: 0
// CHECK-NEXT: Info: 0
// CHECK-NEXT: AddressAlignment: 16
// CHECK: Name: sym1
// CHECK-NEXT: Value: 0x201004
// CHECK-NEXT: Value: 0x201000
// CHECK-NEXT: Size: 8
// CHECK-NEXT: Binding: Global
// CHECK-NEXT: Type: Object
@ -26,7 +26,7 @@
// CHECK-NEXT: Section: .bss
// CHECK: Name: sym2
// CHECK-NEXT: Value: 0x20100C
// CHECK-NEXT: Value: 0x201008
// CHECK-NEXT: Size: 8
// CHECK-NEXT: Binding: Global
// CHECK-NEXT: Type: Object
@ -34,7 +34,7 @@
// CHECK-NEXT: Section: .bss
// CHECK: Name: sym3
// CHECK-NEXT: Value: 0x201014
// CHECK-NEXT: Value: 0x201010
// CHECK-NEXT: Size: 2
// CHECK-NEXT: Binding: Global
// CHECK-NEXT: Type: Object
@ -42,7 +42,7 @@
// CHECK-NEXT: Section: .bss
// CHECK: Name: sym4
// CHECK-NEXT: Value: 0x201000
// CHECK-NEXT: Value: 0x201020
// CHECK-NEXT: Size: 4
// CHECK-NEXT: Binding: Global
// CHECK-NEXT: Type: Object

2
lld/test/ELF/linkerscript/Inputs/common-filespec1.s Normal file
View File

@ -0,0 +1,2 @@
.comm common_uniq_1,8,8
.comm common_multiple,16,8

2
lld/test/ELF/linkerscript/Inputs/common-filespec2.s Normal file
View File

@ -0,0 +1,2 @@
.comm common_uniq_2,16,16
.comm common_multiple,32,8

86
lld/test/ELF/linkerscript/common-exclude.s Normal file
View File

@ -0,0 +1,86 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %tfile0.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/common-filespec1.s -o %tfile1.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/common-filespec2.s -o %tfile2.o
# RUN: echo "SECTIONS { .common.incl : { *(EXCLUDE_FILE (*file2.o) COMMON) } .common.excl : { *(COMMON) } }" > %t.script
# RUN: ld.lld -o %t1 --script %t.script %tfile0.o %tfile1.o %tfile2.o
# RUN: llvm-readobj -s -t %t1 | FileCheck %s
# Commons from file0 and file1 are not excluded, so they must be in .common.incl
# Commons from file2 are excluded from the first rule and should be caught by
# the second in .common.excl
# CHECK: Section {
# CHECK: Index:
# CHECK: Name: .common.incl
# CHECK-NEXT: Type: SHT_NOBITS
# CHECK-NEXT: Flags [
# CHECK-NEXT: SHF_ALLOC
# CHECK-NEXT: SHF_WRITE
# CHECK-NEXT: ]
# CHECK-NEXT: Address: 0x8
# CHECK-NEXT: Offset: 0x
# CHECK-NEXT: Size: 16
# CHECK-NEXT: Link: 0
# CHECK-NEXT: Info: 0
# CHECK-NEXT: AddressAlignment: 8
# CHECK-NEXT: EntrySize: 0
# CHECK-NEXT: }
# CHECK: Section {
# CHECK: Index:
# CHECK: Name: .common.excl
# CHECK-NEXT: Type: SHT_NOBITS
# CHECK-NEXT: Flags [
# CHECK-NEXT: SHF_ALLOC
# CHECK-NEXT: SHF_WRITE
# CHECK-NEXT: ]
# CHECK-NEXT: Address: 0x20
# CHECK-NEXT: Offset: 0x
# CHECK-NEXT: Size: 48
# CHECK-NEXT: Link: 0
# CHECK-NEXT: Info: 0
# CHECK-NEXT: AddressAlignment: 16
# CHECK-NEXT: EntrySize: 0
# CHECK-NEXT: }
# CHECK: Symbol {
# CHECK: Name: common_multiple
# CHECK-NEXT: Value: 0x20
# CHECK-NEXT: Size: 32
# CHECK-NEXT: Binding: Global
# CHECK-NEXT: Type: Object
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: .common.excl
# CHECK-NEXT: }
# CHECK: Symbol {
# CHECK: Name: common_uniq_0
# CHECK-NEXT: Value: 0x8
# CHECK-NEXT: Size: 4
# CHECK-NEXT: Binding: Global
# CHECK-NEXT: Type: Object
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: .common.incl
# CHECK-NEXT: }
# CHECK: Symbol {
# CHECK: Name: common_uniq_1
# CHECK-NEXT: Value: 0x10
# CHECK-NEXT: Size: 8
# CHECK-NEXT: Binding: Global
# CHECK-NEXT: Type: Object
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: .common.incl
# CHECK-NEXT: }
# CHECK: Symbol {
# CHECK: Name: common_uniq_2
# CHECK-NEXT: Value: 0x40
# CHECK-NEXT: Size: 16
# CHECK-NEXT: Binding: Global
# CHECK-NEXT: Type: Object
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: .common.excl
# CHECK-NEXT: }
.globl _start
_start:
jmp _start
.comm common_uniq_0,4,4
.comm common_multiple,8,8

105
lld/test/ELF/linkerscript/common-filespec.s Normal file
View File

@ -0,0 +1,105 @@
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %tfile0.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/common-filespec1.s -o %tfile1.o
# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/common-filespec2.s -o %tfile2.o
# RUN: echo "SECTIONS { .common_0 : { *file0.o(COMMON) } .common_1 : { *file1.o(COMMON) } .common_2 : { *file2.o(COMMON) } }" > %t.script
# RUN: ld.lld -o %t1 --script %t.script %tfile0.o %tfile1.o %tfile2.o
# RUN: llvm-readobj -s -t %t1 | FileCheck %s
# Make sure all 3 sections are allocated and they have sizes and alignments
# corresponding to the commons assigned to them
# CHECK: Section {
# CHECK: Index:
# CHECK: Name: .common_0
# CHECK-NEXT: Type: SHT_NOBITS
# CHECK-NEXT: Flags [
# CHECK-NEXT: SHF_ALLOC
# CHECK-NEXT: SHF_WRITE
# CHECK-NEXT: ]
# CHECK-NEXT: Address: 0x4
# CHECK-NEXT: Offset: 0x
# CHECK-NEXT: Size: 4
# CHECK-NEXT: Link: 0
# CHECK-NEXT: Info: 0
# CHECK-NEXT: AddressAlignment: 4
# CHECK-NEXT: EntrySize: 0
# CHECK-NEXT: }
# CHECK: Section {
# CHECK: Index:
# CHECK: Name: .common_1
# CHECK-NEXT: Type: SHT_NOBITS
# CHECK-NEXT: Flags [
# CHECK-NEXT: SHF_ALLOC
# CHECK-NEXT: SHF_WRITE
# CHECK-NEXT: ]
# CHECK-NEXT: Address: 0x8
# CHECK-NEXT: Offset: 0x
# CHECK-NEXT: Size: 8
# CHECK-NEXT: Link: 0
# CHECK-NEXT: Info: 0
# CHECK-NEXT: AddressAlignment: 8
# CHECK-NEXT: EntrySize: 0
# CHECK-NEXT: }
# CHECK: Section {
# CHECK: Index:
# CHECK: Name: .common_2
# CHECK-NEXT: Type: SHT_NOBITS
# CHECK-NEXT: Flags [
# CHECK-NEXT: SHF_ALLOC
# CHECK-NEXT: SHF_WRITE
# CHECK-NEXT: ]
# CHECK-NEXT: Address: 0x10
# CHECK-NEXT: Offset: 0x
# CHECK-NEXT: Size: 48
# CHECK-NEXT: Link: 0
# CHECK-NEXT: Info: 0
# CHECK-NEXT: AddressAlignment: 16
# CHECK-NEXT: EntrySize: 0
# CHECK-NEXT: }
# Commons with unique name in each file must be assigned to that file's section.
# For a common with multiple definitions, the largest one wins and it must be
# assigned to the section from the file which provided the winning def
# CHECK: Symbol {
# CHECK: Name: common_multiple
# CHECK-NEXT: Value: 0x10
# CHECK-NEXT: Size: 32
# CHECK-NEXT: Binding: Global
# CHECK-NEXT: Type: Object
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: .common_2
# CHECK-NEXT: }
# CHECK: Symbol {
# CHECK: Name: common_uniq_0
# CHECK-NEXT: Value: 0x4
# CHECK-NEXT: Size: 4
# CHECK-NEXT: Binding: Global
# CHECK-NEXT: Type: Object
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: .common_0
# CHECK-NEXT: }
# CHECK: Symbol {
# CHECK: Name: common_uniq_1
# CHECK-NEXT: Value: 0x8
# CHECK-NEXT: Size: 8
# CHECK-NEXT: Binding: Global
# CHECK-NEXT: Type: Object
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: .common_1
# CHECK-NEXT: }
# CHECK: Symbol {
# CHECK: Name: common_uniq_2
# CHECK-NEXT: Value: 0x30
# CHECK-NEXT: Size: 16
# CHECK-NEXT: Binding: Global
# CHECK-NEXT: Type: Object
# CHECK-NEXT: Other: 0
# CHECK-NEXT: Section: .common_2
# CHECK-NEXT: }
.globl _start
_start:
jmp _start
.comm common_uniq_0,4,4
.comm common_multiple,8,8

8
lld/test/ELF/linkerscript/common.s
View File

@ -4,8 +4,6 @@
# RUN: ld.lld -o %t1 --script %t.script %t
# RUN: llvm-readobj -s -t %t1 | FileCheck %s
# q2 alignment is greater than q1, so it should have smaller offset
# because of sorting
# CHECK: Section {
# CHECK: Index:
# CHECK: Name: .common
@ -16,7 +14,7 @@
# CHECK-NEXT: ]
# CHECK-NEXT: Address: 0x200
# CHECK-NEXT: Offset: 0x
# CHECK-NEXT: Size: 256
# CHECK-NEXT: Size: 384
# CHECK-NEXT: Link: 0
# CHECK-NEXT: Info: 0
# CHECK-NEXT: AddressAlignment: 256
@ -24,7 +22,7 @@
# CHECK-NEXT: }
# CHECK: Symbol {
# CHECK: Name: q1
# CHECK-NEXT: Value: 0x280
# CHECK-NEXT: Value: 0x200
# CHECK-NEXT: Size: 128
# CHECK-NEXT: Binding: Global
# CHECK-NEXT: Type: Object
@ -33,7 +31,7 @@
# CHECK-NEXT: }
# CHECK-NEXT: Symbol {
# CHECK-NEXT: Name: q2
# CHECK-NEXT: Value: 0x200
# CHECK-NEXT: Value: 0x300
# CHECK-NEXT: Size: 128
# CHECK-NEXT: Binding: Global
# CHECK-NEXT: Type: Object

5
lld/test/ELF/linkerscript/discard-section-err.s
View File

@ -22,9 +22,4 @@
# RUN: FileCheck -check-prefix=DYNSTR %s
# DYNSTR: discarding .dynstr section is not allowed
# RUN: echo "SECTIONS { /DISCARD/ : { *(COMMON) } }" > %t.script
# RUN: not ld.lld -pie -o %t --script %t.script %t.o 2>&1 | \
# RUN: FileCheck -check-prefix=COMMON %s
# COMMON: discarding COMMON section is not allowed
.comm foo,4,4

2
lld/test/ELF/map-file.s
View File

@ -47,7 +47,7 @@ labs = 0x1AB5
// CHECK-NEXT: 0000000000201014 0000000000000001 4 {{.*}}{{/|\\}}map-file.s.tmp4.a(map-file.s.tmp4.o):(.text)
// CHECK-NEXT: 0000000000201014 0000000000000000 0 baz
// CHECK-NEXT: 0000000000202000 0000000000000004 16 .bss
// CHECK-NEXT: 0000000000202000 0000000000000004 16 <internal>:(COMMON)
// CHECK-NEXT: 0000000000202000 0000000000000004 16 {{.*}}{{/|\\}}map-file.s.tmp1.o:(COMMON)
// CHECK-NEXT: 0000000000202000 0000000000000004 0 common
// CHECK-NEXT: 0000000000000000 0000000000000008 1 .comment
// CHECK-NEXT: 0000000000000000 0000000000000008 1 <internal>:(.comment)