[lld] r312796 - Currently lld creates a single section to collect all commons. There is no way

Dmitry Mikulin via llvm-commits llvm-commits at lists.llvm.org
Fri Sep 8 09:22:43 PDT 2017


Author: dmikulin
Date: Fri Sep  8 09:22:43 2017
New Revision: 312796

URL: http://llvm.org/viewvc/llvm-project?rev=312796&view=rev
Log:
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

Added:
    lld/trunk/test/ELF/linkerscript/Inputs/common-filespec1.s
    lld/trunk/test/ELF/linkerscript/Inputs/common-filespec2.s
    lld/trunk/test/ELF/linkerscript/common-exclude.s
    lld/trunk/test/ELF/linkerscript/common-filespec.s
Modified:
    lld/trunk/ELF/LinkerScript.cpp
    lld/trunk/ELF/MapFile.cpp
    lld/trunk/ELF/Symbols.cpp
    lld/trunk/ELF/Symbols.h
    lld/trunk/ELF/SyntheticSections.cpp
    lld/trunk/ELF/SyntheticSections.h
    lld/trunk/ELF/Writer.cpp
    lld/trunk/test/ELF/common.s
    lld/trunk/test/ELF/linkerscript/common.s
    lld/trunk/test/ELF/linkerscript/discard-section-err.s
    lld/trunk/test/ELF/map-file.s

Modified: lld/trunk/ELF/LinkerScript.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LinkerScript.cpp?rev=312796&r1=312795&r2=312796&view=diff
==============================================================================
--- lld/trunk/ELF/LinkerScript.cpp (original)
+++ lld/trunk/ELF/LinkerScript.cpp Fri Sep  8 09:22:43 2017
@@ -174,17 +174,17 @@ bool BytesDataCommand::classof(const Bas
   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
       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
 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(c
     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;

Modified: lld/trunk/ELF/MapFile.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/MapFile.cpp?rev=312796&r1=312795&r2=312796&view=diff
==============================================================================
--- lld/trunk/ELF/MapFile.cpp (original)
+++ lld/trunk/ELF/MapFile.cpp Fri Sep  8 09:22:43 2017
@@ -57,7 +57,7 @@ template <class ELFT> static std::vector
             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(ArrayR
   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

Modified: lld/trunk/ELF/Symbols.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Symbols.cpp?rev=312796&r1=312795&r2=312796&view=diff
==============================================================================
--- lld/trunk/ELF/Symbols.cpp (original)
+++ lld/trunk/ELF/Symbols.cpp Fri Sep  8 09:22:43 2017
@@ -99,11 +99,13 @@ static uint64_t getSymVA(const SymbolBod
     }
     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::getOutputSect
     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;
   }
 

Modified: lld/trunk/ELF/Symbols.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Symbols.h?rev=312796&r1=312795&r2=312796&view=diff
==============================================================================
--- lld/trunk/ELF/Symbols.h (original)
+++ lld/trunk/ELF/Symbols.h Fri Sep  8 09:22:43 2017
@@ -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.

Modified: lld/trunk/ELF/SyntheticSections.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SyntheticSections.cpp?rev=312796&r1=312795&r2=312796&view=diff
==============================================================================
--- lld/trunk/ELF/SyntheticSections.cpp (original)
+++ lld/trunk/ELF/SyntheticSections.cpp Fri Sep  8 09:22:43 2017
@@ -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::stable_sort(Syms.begin(), Syms.end(),
-                   [](const DefinedCommon *A, const DefinedCommon *B) {
-                     return A->Alignment > B->Alignment;
-                   });
+  std::vector<InputSection *> Ret;
+  for (Symbol *S : Symtab->getSymbols()) {
+    auto *Sym = dyn_cast<DefinedCommon>(S->body());
+    if (!Sym || !Sym->Live)
+      continue;
 
-  // 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<ELF32
 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>();

Modified: lld/trunk/ELF/SyntheticSections.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/SyntheticSections.h?rev=312796&r1=312795&r2=312796&view=diff
==============================================================================
--- lld/trunk/ELF/SyntheticSections.h (original)
+++ lld/trunk/ELF/SyntheticSections.h Fri Sep  8 09:22:43 2017
@@ -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;

Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=312796&r1=312795&r2=312796&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Fri Sep  8 09:22:43 2017
@@ -299,9 +299,9 @@ template <class ELFT> void Writer<ELFT>:
     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);

Modified: lld/trunk/test/ELF/common.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/common.s?rev=312796&r1=312795&r2=312796&view=diff
==============================================================================
--- lld/trunk/test/ELF/common.s (original)
+++ lld/trunk/test/ELF/common.s Fri Sep  8 09:22:43 2017
@@ -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

Added: lld/trunk/test/ELF/linkerscript/Inputs/common-filespec1.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/linkerscript/Inputs/common-filespec1.s?rev=312796&view=auto
==============================================================================
--- lld/trunk/test/ELF/linkerscript/Inputs/common-filespec1.s (added)
+++ lld/trunk/test/ELF/linkerscript/Inputs/common-filespec1.s Fri Sep  8 09:22:43 2017
@@ -0,0 +1,2 @@
+.comm common_uniq_1,8,8
+.comm common_multiple,16,8

Added: lld/trunk/test/ELF/linkerscript/Inputs/common-filespec2.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/linkerscript/Inputs/common-filespec2.s?rev=312796&view=auto
==============================================================================
--- lld/trunk/test/ELF/linkerscript/Inputs/common-filespec2.s (added)
+++ lld/trunk/test/ELF/linkerscript/Inputs/common-filespec2.s Fri Sep  8 09:22:43 2017
@@ -0,0 +1,2 @@
+.comm common_uniq_2,16,16
+.comm common_multiple,32,8

Added: lld/trunk/test/ELF/linkerscript/common-exclude.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/linkerscript/common-exclude.s?rev=312796&view=auto
==============================================================================
--- lld/trunk/test/ELF/linkerscript/common-exclude.s (added)
+++ lld/trunk/test/ELF/linkerscript/common-exclude.s Fri Sep  8 09:22:43 2017
@@ -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

Added: lld/trunk/test/ELF/linkerscript/common-filespec.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/linkerscript/common-filespec.s?rev=312796&view=auto
==============================================================================
--- lld/trunk/test/ELF/linkerscript/common-filespec.s (added)
+++ lld/trunk/test/ELF/linkerscript/common-filespec.s Fri Sep  8 09:22:43 2017
@@ -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

Modified: lld/trunk/test/ELF/linkerscript/common.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/linkerscript/common.s?rev=312796&r1=312795&r2=312796&view=diff
==============================================================================
--- lld/trunk/test/ELF/linkerscript/common.s (original)
+++ lld/trunk/test/ELF/linkerscript/common.s Fri Sep  8 09:22:43 2017
@@ -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

Modified: lld/trunk/test/ELF/linkerscript/discard-section-err.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/linkerscript/discard-section-err.s?rev=312796&r1=312795&r2=312796&view=diff
==============================================================================
--- lld/trunk/test/ELF/linkerscript/discard-section-err.s (original)
+++ lld/trunk/test/ELF/linkerscript/discard-section-err.s Fri Sep  8 09:22:43 2017
@@ -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

Modified: lld/trunk/test/ELF/map-file.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/map-file.s?rev=312796&r1=312795&r2=312796&view=diff
==============================================================================
--- lld/trunk/test/ELF/map-file.s (original)
+++ lld/trunk/test/ELF/map-file.s Fri Sep  8 09:22:43 2017
@@ -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)




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