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Revert r221014: "Refactor duplicated code in liking GlobalValues." 

This commit introduces heap-use-after-free detected by ASan. Here is the output
for one of several tests that detect it:

******************** TEST 'LLVM :: Linker/AppendingLinkage.ll' FAILED ********************
Command Output (stderr):
--
=================================================================
==2122==ERROR: AddressSanitizer: heap-use-after-free on address 0x60c00000b9c8 at pc 0x0000005d05d1 bp 0x7fff64ed27c0 sp 0x7fff64ed27b8
READ of size 4 at 0x60c00000b9c8 thread T0
    #0 0x5d05d0 in llvm::GlobalValue::setUnnamedAddr(bool) /usr/local/google/home/chandlerc/src/llvm/build/../include/llvm/IR/GlobalValue.h:115:35
    #1 0x69fff1 in (anonymous namespace)::ModuleLinker::linkGlobalValueProto(llvm::GlobalValue*) /usr/local/google/home/chandlerc/src/llvm/build/../lib/Linker/LinkModules.cpp:1041:5
    #2 0x697229 in (anonymous namespace)::ModuleLinker::run() /usr/local/google/home/chandlerc/src/llvm/build/../lib/Linker/LinkModules.cpp:1485:9
    #3 0x696542 in llvm::Linker::linkInModule(llvm::Module*) /usr/local/google/home/chandlerc/src/llvm/build/../lib/Linker/LinkModules.cpp:1621:10
    #4 0x4a2db7 in main /usr/local/google/home/chandlerc/src/llvm/build/../tools/llvm-link/llvm-link.cpp:116:9
    #5 0x7f4ae61e5ec4 in __libc_start_main /build/buildd/eglibc-2.19/csu/libc-start.c:287
    #6 0x41eb71 in _start (/usr/local/google/home/chandlerc/src/llvm/build/bin/llvm-link+0x41eb71)

0x60c00000b9c8 is located 72 bytes inside of 128-byte region [0x60c00000b980,0x60c00000ba00)
freed by thread T0 here:
    #0 0x4a1e6b in operator delete(void*) /usr/local/google/home/chandlerc/src/llvm/opt-build/../projects/compiler-rt/lib/asan/asan_new_delete.cc:94:3
    #1 0x5d1a7a in llvm::iplist<llvm::GlobalVariable, llvm::ilist_traits<llvm::GlobalVariable> >::erase(llvm::ilist_iterator<llvm::GlobalVariable>) /usr/local/google/home/chandlerc/src/llvm/build/../inclu
de/llvm/ADT/ilist.h:466:5
    #2 0x5d1980 in llvm::GlobalVariable::eraseFromParent() /usr/local/google/home/chandlerc/src/llvm/build/../lib/IR/Globals.cpp:204:3
    #3 0x6a8a4d in (anonymous namespace)::ModuleLinker::linkAppendingVarProto(llvm::GlobalVariable*, llvm::GlobalVariable const*) /usr/local/google/home/chandlerc/src/llvm/build/../lib/Linker/LinkModules.
cpp:980:3
    #4 0x6a7403 in (anonymous namespace)::ModuleLinker::linkGlobalVariableProto(llvm::GlobalVariable const*, llvm::GlobalValue*, bool) /usr/local/google/home/chandlerc/src/llvm/build/../lib/Linker/LinkMod
ules.cpp:1074:11
    #5 0x69ff4e in (anonymous namespace)::ModuleLinker::linkGlobalValueProto(llvm::GlobalValue*) /usr/local/google/home/chandlerc/src/llvm/build/../lib/Linker/LinkModules.cpp:1028:13
    #6 0x697229 in (anonymous namespace)::ModuleLinker::run() /usr/local/google/home/chandlerc/src/llvm/build/../lib/Linker/LinkModules.cpp:1485:9
    #7 0x696542 in llvm::Linker::linkInModule(llvm::Module*) /usr/local/google/home/chandlerc/src/llvm/build/../lib/Linker/LinkModules.cpp:1621:10
    #8 0x4a2db7 in main /usr/local/google/home/chandlerc/src/llvm/build/../tools/llvm-link/llvm-link.cpp:116:9
    #9 0x7f4ae61e5ec4 in __libc_start_main /build/buildd/eglibc-2.19/csu/libc-start.c:287

previously allocated by thread T0 here:
    #0 0x4a192b in operator new(unsigned long) /usr/local/google/home/chandlerc/src/llvm/opt-build/../projects/compiler-rt/lib/asan/asan_new_delete.cc:62:35
    #1 0x61d85c in llvm::User::operator new(unsigned long, unsigned int) /usr/local/google/home/chandlerc/src/llvm/build/../lib/IR/User.cpp:57:19
    #2 0x6a7525 in (anonymous namespace)::ModuleLinker::linkGlobalVariableProto(llvm::GlobalVariable const*, llvm::GlobalValue*, bool) /usr/local/google/home/chandlerc/src/llvm/build/../lib/Linker/LinkMod
ules.cpp:1100:3
    #3 0x69ff4e in (anonymous namespace)::ModuleLinker::linkGlobalValueProto(llvm::GlobalValue*) /usr/local/google/home/chandlerc/src/llvm/build/../lib/Linker/LinkModules.cpp:1028:13
    #4 0x697229 in (anonymous namespace)::ModuleLinker::run() /usr/local/google/home/chandlerc/src/llvm/build/../lib/Linker/LinkModules.cpp:1485:9
    #5 0x696542 in llvm::Linker::linkInModule(llvm::Module*) /usr/local/google/home/chandlerc/src/llvm/build/../lib/Linker/LinkModules.cpp:1621:10
    #6 0x4a2db7 in main /usr/local/google/home/chandlerc/src/llvm/build/../tools/llvm-link/llvm-link.cpp:116:9
    #7 0x7f4ae61e5ec4 in __libc_start_main /build/buildd/eglibc-2.19/csu/libc-start.c:287

SUMMARY: AddressSanitizer: heap-use-after-free /usr/local/google/home/chandlerc/src/llvm/build/../include/llvm/IR/GlobalValue.h:115 llvm::GlobalValue::setUnnamedAddr(bool)
Shadow bytes around the buggy address:
  0x0c187fff96e0: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
  0x0c187fff96f0: 00 00 00 00 00 00 00 fa fa fa fa fa fa fa fa fa
  0x0c187fff9700: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fa
  0x0c187fff9710: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
  0x0c187fff9720: 00 00 00 00 00 00 00 00 fa fa fa fa fa fa fa fa
=>0x0c187fff9730: fd fd fd fd fd fd fd fd fd[fd]fd fd fd fd fd fd
  0x0c187fff9740: fa fa fa fa fa fa fa fa fd fd fd fd fd fd fd fd
  0x0c187fff9750: fd fd fd fd fd fd fd fa fa fa fa fa fa fa fa fa
  0x0c187fff9760: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c187fff9770: fa fa fa fa fa fa fa fa fd fd fd fd fd fd fd fd
  0x0c187fff9780: fd fd fd fd fd fd fd fd fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07
  Heap left redzone:       fa
  Heap right redzone:      fb
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack partial redzone:   f4
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  ASan internal:           fe
==2122==ABORTING

llvm-svn: 221096
This commit is contained in:
Chandler Carruth 2014-11-02 09:10:31 +00:00
parent 4aa49b2054
commit fd38af2d13
3 changed files with 251 additions and 142 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

379
llvm/lib/Linker/LinkModules.cpp
View File

@ -453,6 +453,13 @@ namespace {
bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK, bool getComdatResult(const Comdat *SrcC, Comdat::SelectionKind &SK,
bool &LinkFromSrc); bool &LinkFromSrc);
/// This analyzes the two global values and determines what the result will
/// look like in the destination module.
bool getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
GlobalValue::LinkageTypes &LT,
GlobalValue::VisibilityTypes &Vis,
bool &LinkFromSrc);
/// Given a global in the source module, return the global in the /// Given a global in the source module, return the global in the
/// destination module that is being linked to, if any. /// destination module that is being linked to, if any.
GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) { GlobalValue *getLinkedToGlobal(const GlobalValue *SrcGV) {
@ -481,15 +488,9 @@ namespace {
bool linkAppendingVarProto(GlobalVariable *DstGV, bool linkAppendingVarProto(GlobalVariable *DstGV,
const GlobalVariable *SrcGV); const GlobalVariable *SrcGV);
bool linkGlobalProto(const GlobalVariable *SrcGV);
bool linkGlobalValueProto(GlobalValue *GV); bool linkFunctionProto(Function *SrcF);
GlobalValue *linkGlobalVariableProto(const GlobalVariable *SGVar, bool linkAliasProto(GlobalAlias *SrcA);
GlobalValue *DGV, bool LinkFromSrc);
GlobalValue *linkFunctionProto(const Function *SF, GlobalValue *DGV,
bool LinkFromSrc);
GlobalValue *linkGlobalAliasProto(const GlobalAlias *SGA, GlobalValue *DGV,
bool LinkFromSrc);
bool linkModuleFlagsMetadata(); bool linkModuleFlagsMetadata();
void linkAppendingVarInit(const AppendingVarInfo &AVI); void linkAppendingVarInit(const AppendingVarInfo &AVI);
@ -687,12 +688,6 @@ bool ModuleLinker::getComdatResult(const Comdat *SrcC,
bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc, bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
const GlobalValue &Dest, const GlobalValue &Dest,
const GlobalValue &Src) { const GlobalValue &Src) {
// We always have to add Src if it has appending linkage.
if (Src.hasAppendingLinkage()) {
LinkFromSrc = true;
return false;
}
bool SrcIsDeclaration = Src.isDeclarationForLinker(); bool SrcIsDeclaration = Src.isDeclarationForLinker();
bool DestIsDeclaration = Dest.isDeclarationForLinker(); bool DestIsDeclaration = Dest.isDeclarationForLinker();
@ -762,6 +757,36 @@ bool ModuleLinker::shouldLinkFromSource(bool &LinkFromSrc,
"': symbol multiply defined!"); "': symbol multiply defined!");
} }
/// This analyzes the two global values and determines what the result will look
/// like in the destination module. In particular, it computes the resultant
/// linkage type and visibility, computes whether the global in the source
/// should be copied over to the destination (replacing the existing one), and
/// computes whether this linkage is an error or not.
bool ModuleLinker::getLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
GlobalValue::LinkageTypes &LT,
GlobalValue::VisibilityTypes &Vis,
bool &LinkFromSrc) {
assert(Dest && "Must have two globals being queried");
assert(!Src->hasLocalLinkage() &&
"If Src has internal linkage, Dest shouldn't be set!");
if (shouldLinkFromSource(LinkFromSrc, *Dest, *Src))
return true;
if (LinkFromSrc)
LT = Src->getLinkage();
else
LT = Dest->getLinkage();
// Compute the visibility. We follow the rules in the System V Application
// Binary Interface.
assert(!GlobalValue::isLocalLinkage(LT) &&
"Symbols with local linkage should not be merged");
Vis = isLessConstraining(Src->getVisibility(), Dest->getVisibility()) ?
Dest->getVisibility() : Src->getVisibility();
return false;
}
/// Loop over all of the linked values to compute type mappings. For example, /// Loop over all of the linked values to compute type mappings. For example,
/// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct /// if we link "extern Foo *x" and "Foo *x = NULL", then we have two struct
/// types 'Foo' but one got renamed when the module was loaded into the same /// types 'Foo' but one got renamed when the module was loaded into the same
@ -985,164 +1010,256 @@ bool ModuleLinker::linkAppendingVarProto(GlobalVariable *DstGV,
return false; return false;
} }
bool ModuleLinker::linkGlobalValueProto(GlobalValue *SGV) { /// Loop through the global variables in the src module and merge them into the
/// dest module.
bool ModuleLinker::linkGlobalProto(const GlobalVariable *SGV) {
GlobalValue *DGV = getLinkedToGlobal(SGV); GlobalValue *DGV = getLinkedToGlobal(SGV);
bool LinkFromSrc = true; llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
Comdat *C = nullptr;
GlobalValue::VisibilityTypes Visibility = SGV->getVisibility();
bool HasUnnamedAddr = SGV->hasUnnamedAddr(); bool HasUnnamedAddr = SGV->hasUnnamedAddr();
unsigned Alignment = SGV->getAlignment();
bool LinkFromSrc = false;
Comdat *DC = nullptr;
if (const Comdat *SC = SGV->getComdat()) { if (const Comdat *SC = SGV->getComdat()) {
Comdat::SelectionKind SK; Comdat::SelectionKind SK;
std::tie(SK, LinkFromSrc) = ComdatsChosen[SC]; std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
C = DstM->getOrInsertComdat(SC->getName()); DC = DstM->getOrInsertComdat(SC->getName());
C->setSelectionKind(SK); DC->setSelectionKind(SK);
} else if (DGV) {
if (shouldLinkFromSource(LinkFromSrc, *DGV, *SGV))
return true;
}
if (!LinkFromSrc) {
// Track the source global so that we don't attempt to copy it over when
// processing global initializers.
DoNotLinkFromSource.insert(SGV);
if (DGV)
// Make sure to remember this mapping.
ValueMap[SGV] =
ConstantExpr::getBitCast(DGV, TypeMap.get(SGV->getType()));
} }
if (DGV) { if (DGV) {
Visibility = isLessConstraining(Visibility, DGV->getVisibility()) if (!DC) {
? DGV->getVisibility() // Concatenation of appending linkage variables is magic and handled later.
: Visibility; if (DGV->hasAppendingLinkage() || SGV->hasAppendingLinkage())
HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr(); return linkAppendingVarProto(cast<GlobalVariable>(DGV), SGV);
}
if (!LinkFromSrc && !DGV) // Determine whether linkage of these two globals follows the source
return false; // module's definition or the destination module's definition.
GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
GlobalValue::VisibilityTypes NV;
if (getLinkageResult(DGV, SGV, NewLinkage, NV, LinkFromSrc))
return true;
NewVisibility = NV;
HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
if (DGV->hasCommonLinkage() && SGV->hasCommonLinkage())
Alignment = std::max(Alignment, DGV->getAlignment());
else if (!LinkFromSrc)
Alignment = DGV->getAlignment();
GlobalValue *NewGV; // If we're not linking from the source, then keep the definition that we
if (auto *SGVar = dyn_cast<GlobalVariable>(SGV)) { // have.
NewGV = linkGlobalVariableProto(SGVar, DGV, LinkFromSrc); if (!LinkFromSrc) {
if (!NewGV) // Special case for const propagation.
return true; if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) {
} else if (auto *SF = dyn_cast<Function>(SGV)) { DGVar->setAlignment(Alignment);
NewGV = linkFunctionProto(SF, DGV, LinkFromSrc);
} else {
NewGV = linkGlobalAliasProto(cast<GlobalAlias>(SGV), DGV, LinkFromSrc);
}
if (NewGV) { if (DGVar->isDeclaration() && !SGV->isConstant())
if (NewGV != DGV) DGVar->setConstant(false);
copyGVAttributes(NewGV, SGV); }
NewGV->setUnnamedAddr(HasUnnamedAddr); // Set calculated linkage, visibility and unnamed_addr.
NewGV->setVisibility(Visibility); DGV->setLinkage(NewLinkage);
DGV->setVisibility(*NewVisibility);
if (auto *NewGO = dyn_cast<GlobalObject>(NewGV)) { DGV->setUnnamedAddr(HasUnnamedAddr);
if (C)
NewGO->setComdat(C);
}
// Make sure to remember this mapping.
if (NewGV != DGV) {
if (DGV) {
DGV->replaceAllUsesWith(
ConstantExpr::getBitCast(NewGV, DGV->getType()));
DGV->eraseFromParent();
} }
ValueMap[SGV] = NewGV; }
if (!LinkFromSrc) {
// Make sure to remember this mapping.
ValueMap[SGV] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGV->getType()));
// Track the source global so that we don't attempt to copy it over when
// processing global initializers.
DoNotLinkFromSource.insert(SGV);
return false;
} }
} }
return false; // If the Comdat this variable was inside of wasn't selected, skip it.
} if (DC && !DGV && !LinkFromSrc) {
DoNotLinkFromSource.insert(SGV);
/// Loop through the global variables in the src module and merge them into the return false;
/// dest module.
GlobalValue *ModuleLinker::linkGlobalVariableProto(const GlobalVariable *SGVar,
GlobalValue *DGV,
bool LinkFromSrc) {
unsigned Alignment = 0;
bool ClearConstant = false;
if (DGV) {
// Concatenation of appending linkage variables is magic and handled later.
if (DGV->hasAppendingLinkage()) {
if (linkAppendingVarProto(cast<GlobalVariable>(DGV), SGVar))
return nullptr;
return DGV;
}
if (DGV->hasCommonLinkage() && SGVar->hasCommonLinkage())
Alignment = std::max(SGVar->getAlignment(), DGV->getAlignment());
auto *DGVar = dyn_cast<GlobalVariable>(DGV);
if (!SGVar->isConstant() || (DGVar && !DGVar->isConstant()))
ClearConstant = true;
}
if (!LinkFromSrc) {
if (auto *NewGVar = dyn_cast<GlobalVariable>(DGV)) {
if (Alignment)
NewGVar->setAlignment(Alignment);
if (NewGVar->isDeclaration() && ClearConstant)
NewGVar->setConstant(false);
}
return DGV;
} }
// No linking to be performed or linking from the source: simply create an // No linking to be performed or linking from the source: simply create an
// identical version of the symbol over in the dest module... the // identical version of the symbol over in the dest module... the
// initializer will be filled in later by LinkGlobalInits. // initializer will be filled in later by LinkGlobalInits.
GlobalVariable *NewDGV = new GlobalVariable( GlobalVariable *NewDGV =
*DstM, TypeMap.get(SGVar->getType()->getElementType()), new GlobalVariable(*DstM, TypeMap.get(SGV->getType()->getElementType()),
SGVar->isConstant(), SGVar->getLinkage(), /*init*/ nullptr, SGV->isConstant(), SGV->getLinkage(), /*init*/nullptr,
SGVar->getName(), /*insertbefore*/ nullptr, SGVar->getThreadLocalMode(), SGV->getName(), /*insertbefore*/nullptr,
SGVar->getType()->getAddressSpace()); SGV->getThreadLocalMode(),
SGV->getType()->getAddressSpace());
// Propagate alignment, visibility and section info.
copyGVAttributes(NewDGV, SGV);
NewDGV->setAlignment(Alignment);
if (NewVisibility)
NewDGV->setVisibility(*NewVisibility);
NewDGV->setUnnamedAddr(HasUnnamedAddr);
if (Alignment) if (DC)
NewDGV->setAlignment(Alignment); NewDGV->setComdat(DC);
return NewDGV; if (DGV) {
DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, DGV->getType()));
DGV->eraseFromParent();
}
// Make sure to remember this mapping.
ValueMap[SGV] = NewDGV;
return false;
} }
/// Link the function in the source module into the destination module if /// Link the function in the source module into the destination module if
/// needed, setting up mapping information. /// needed, setting up mapping information.
GlobalValue *ModuleLinker::linkFunctionProto(const Function *SF, bool ModuleLinker::linkFunctionProto(Function *SF) {
GlobalValue *DGV, GlobalValue *DGV = getLinkedToGlobal(SF);
bool LinkFromSrc) { llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
if (!LinkFromSrc) bool HasUnnamedAddr = SF->hasUnnamedAddr();
return DGV;
bool LinkFromSrc = false;
Comdat *DC = nullptr;
if (const Comdat *SC = SF->getComdat()) {
Comdat::SelectionKind SK;
std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
DC = DstM->getOrInsertComdat(SC->getName());
DC->setSelectionKind(SK);
}
if (DGV) {
if (!DC) {
GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
GlobalValue::VisibilityTypes NV;
if (getLinkageResult(DGV, SF, NewLinkage, NV, LinkFromSrc))
return true;
NewVisibility = NV;
HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
if (!LinkFromSrc) {
// Set calculated linkage
DGV->setLinkage(NewLinkage);
DGV->setVisibility(*NewVisibility);
DGV->setUnnamedAddr(HasUnnamedAddr);
}
}
if (!LinkFromSrc) {
// Make sure to remember this mapping.
ValueMap[SF] = ConstantExpr::getBitCast(DGV, TypeMap.get(SF->getType()));
// Track the function from the source module so we don't attempt to remap
// it.
DoNotLinkFromSource.insert(SF);
return false;
}
}
// If the function is to be lazily linked, don't create it just yet. // If the function is to be lazily linked, don't create it just yet.
// The ValueMaterializerTy will deal with creating it if it's used. // The ValueMaterializerTy will deal with creating it if it's used.
if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() || if (!DGV && (SF->hasLocalLinkage() || SF->hasLinkOnceLinkage() ||
SF->hasAvailableExternallyLinkage())) { SF->hasAvailableExternallyLinkage())) {
DoNotLinkFromSource.insert(SF); DoNotLinkFromSource.insert(SF);
return nullptr; return false;
}
// If the Comdat this function was inside of wasn't selected, skip it.
if (DC && !DGV && !LinkFromSrc) {
DoNotLinkFromSource.insert(SF);
return false;
} }
// If there is no linkage to be performed or we are linking from the source, // If there is no linkage to be performed or we are linking from the source,
// bring SF over. // bring SF over.
return Function::Create(TypeMap.get(SF->getFunctionType()), SF->getLinkage(), Function *NewDF = Function::Create(TypeMap.get(SF->getFunctionType()),
SF->getName(), DstM); SF->getLinkage(), SF->getName(), DstM);
copyGVAttributes(NewDF, SF);
if (NewVisibility)
NewDF->setVisibility(*NewVisibility);
NewDF->setUnnamedAddr(HasUnnamedAddr);
if (DC)
NewDF->setComdat(DC);
if (DGV) {
// Any uses of DF need to change to NewDF, with cast.
DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, DGV->getType()));
DGV->eraseFromParent();
}
ValueMap[SF] = NewDF;
return false;
} }
/// Set up prototypes for any aliases that come over from the source module. /// Set up prototypes for any aliases that come over from the source module.
GlobalValue *ModuleLinker::linkGlobalAliasProto(const GlobalAlias *SGA, bool ModuleLinker::linkAliasProto(GlobalAlias *SGA) {
GlobalValue *DGV, GlobalValue *DGV = getLinkedToGlobal(SGA);
bool LinkFromSrc) { llvm::Optional<GlobalValue::VisibilityTypes> NewVisibility;
if (!LinkFromSrc) bool HasUnnamedAddr = SGA->hasUnnamedAddr();
return DGV;
bool LinkFromSrc = false;
Comdat *DC = nullptr;
if (const Comdat *SC = SGA->getComdat()) {
Comdat::SelectionKind SK;
std::tie(SK, LinkFromSrc) = ComdatsChosen[SC];
DC = DstM->getOrInsertComdat(SC->getName());
DC->setSelectionKind(SK);
}
if (DGV) {
if (!DC) {
GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage;
GlobalValue::VisibilityTypes NV;
if (getLinkageResult(DGV, SGA, NewLinkage, NV, LinkFromSrc))
return true;
NewVisibility = NV;
HasUnnamedAddr = HasUnnamedAddr && DGV->hasUnnamedAddr();
if (!LinkFromSrc) {
// Set calculated linkage.
DGV->setLinkage(NewLinkage);
DGV->setVisibility(*NewVisibility);
DGV->setUnnamedAddr(HasUnnamedAddr);
}
}
if (!LinkFromSrc) {
// Make sure to remember this mapping.
ValueMap[SGA] = ConstantExpr::getBitCast(DGV,TypeMap.get(SGA->getType()));
// Track the alias from the source module so we don't attempt to remap it.
DoNotLinkFromSource.insert(SGA);
return false;
}
}
// If the Comdat this alias was inside of wasn't selected, skip it.
if (DC && !DGV && !LinkFromSrc) {
DoNotLinkFromSource.insert(SGA);
return false;
}
// If there is no linkage to be performed or we're linking from the source, // If there is no linkage to be performed or we're linking from the source,
// bring over SGA. // bring over SGA.
auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType())); auto *PTy = cast<PointerType>(TypeMap.get(SGA->getType()));
return GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(), auto *NewDA =
SGA->getLinkage(), SGA->getName(), DstM); GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
SGA->getLinkage(), SGA->getName(), DstM);
copyGVAttributes(NewDA, SGA);
if (NewVisibility)
NewDA->setVisibility(*NewVisibility);
NewDA->setUnnamedAddr(HasUnnamedAddr);
if (DGV) {
// Any uses of DGV need to change to NewDA, with cast.
DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDA, DGV->getType()));
DGV->eraseFromParent();
}
ValueMap[SGA] = NewDA;
return false;
} }
static void getArrayElements(const Constant *C, static void getArrayElements(const Constant *C,
@ -1482,7 +1599,7 @@ bool ModuleLinker::run() {
// initializers (which could refer to functions not yet mapped over). // initializers (which could refer to functions not yet mapped over).
for (Module::global_iterator I = SrcM->global_begin(), for (Module::global_iterator I = SrcM->global_begin(),
E = SrcM->global_end(); I != E; ++I) E = SrcM->global_end(); I != E; ++I)
if (linkGlobalValueProto(I)) if (linkGlobalProto(I))
return true; return true;
// Link the functions together between the two modules, without doing function // Link the functions together between the two modules, without doing function
@ -1491,13 +1608,13 @@ bool ModuleLinker::run() {
// all of the global values that may be referenced are available in our // all of the global values that may be referenced are available in our
// ValueMap. // ValueMap.
for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I) for (Module::iterator I = SrcM->begin(), E = SrcM->end(); I != E; ++I)
if (linkGlobalValueProto(I)) if (linkFunctionProto(I))
return true; return true;
// If there were any aliases, link them now. // If there were any aliases, link them now.
for (Module::alias_iterator I = SrcM->alias_begin(), for (Module::alias_iterator I = SrcM->alias_begin(),
E = SrcM->alias_end(); I != E; ++I) E = SrcM->alias_end(); I != E; ++I)
if (linkGlobalValueProto(I)) if (linkAliasProto(I))
return true; return true;
for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i) for (unsigned i = 0, e = AppendingVars.size(); i != e; ++i)

3
llvm/test/Linker/Inputs/visibility.ll
View File

@ -1,10 +1,7 @@
$c1 = comdat any
; Variables ; Variables
@v1 = weak hidden global i32 0 @v1 = weak hidden global i32 0
@v2 = weak protected global i32 0 @v2 = weak protected global i32 0
@v3 = weak hidden global i32 0 @v3 = weak hidden global i32 0
@v4 = hidden global i32 1, comdat $c1
; Aliases ; Aliases
@a1 = weak hidden alias i32* @v1 @a1 = weak hidden alias i32* @v1

11
llvm/test/Linker/visibility.ll
View File

@ -4,21 +4,16 @@
; The values in this file are strong, the ones in Inputs/visibility.ll are weak, ; The values in this file are strong, the ones in Inputs/visibility.ll are weak,
; but we should still get the visibility from them. ; but we should still get the visibility from them.
$c1 = comdat any
; Variables ; Variables
; CHECK-DAG: @v1 = hidden global i32 0 ; CHECK: @v1 = hidden global i32 0
@v1 = global i32 0 @v1 = global i32 0
; CHECK-DAG: @v2 = protected global i32 0 ; CHECK: @v2 = protected global i32 0
@v2 = global i32 0 @v2 = global i32 0
; CHECK-DAG: @v3 = hidden global i32 0 ; CHECK: @v3 = hidden global i32 0
@v3 = protected global i32 0 @v3 = protected global i32 0
; CHECK-DAG: @v4 = hidden global i32 1, comdat $c1
@v4 = global i32 1, comdat $c1
; Aliases ; Aliases
; CHECK: @a1 = hidden alias i32* @v1 ; CHECK: @a1 = hidden alias i32* @v1