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Update for llvm api change.

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Now that llvm cannot represent alias cycles, we have to diagnose erros just
before trying to close the cycle. This degrades the errors a bit. The real
solution is what it was before: if we want to provide good errors for these
cases, we have to be able to find a clang level decl given a mangled name
and produce the error from Sema.

llvm-svn: 209008
This commit is contained in:
Rafael Espindola
2014-05-16 19:35:48 +00:00
parent 6b238633b7
commit b2633b9793
11 changed files with 71 additions and 58 deletions
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71
clang/lib/CodeGen/CodeGenModule.cpp
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@@ -238,46 +238,18 @@ void CodeGenModule::checkAliases() {
llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
auto *Alias = cast<llvm::GlobalAlias>(Entry);
llvm::GlobalValue *GV = Alias->getAliasedGlobal();
if (!GV) {
Error = true;
Diags.Report(AA->getLocation(), diag::err_cyclic_alias);
} else if (GV->isDeclaration()) {
if (GV->isDeclaration()) {
Error = true;
Diags.Report(AA->getLocation(), diag::err_alias_to_undefined);
}
llvm::Constant *Aliasee = Alias->getAliasee();
llvm::GlobalValue *AliaseeGV;
if (auto CE = dyn_cast<llvm::ConstantExpr>(Aliasee)) {
assert((CE->getOpcode() == llvm::Instruction::BitCast ||
CE->getOpcode() == llvm::Instruction::AddrSpaceCast) &&
"Unsupported aliasee");
AliaseeGV = cast<llvm::GlobalValue>(CE->getOperand(0));
} else {
AliaseeGV = cast<llvm::GlobalValue>(Aliasee);
}
llvm::GlobalObject *Aliasee = Alias->getAliasee();
if (const SectionAttr *SA = D->getAttr<SectionAttr>()) {
StringRef AliasSection = SA->getName();
if (AliasSection != AliaseeGV->getSection())
if (AliasSection != Aliasee->getSection())
Diags.Report(SA->getLocation(), diag::warn_alias_with_section)
<< AliasSection;
}
// We have to handle alias to weak aliases in here. LLVM itself disallows
// this since the object semantics would not match the IL one. For
// compatibility with gcc we implement it by just pointing the alias
// to its aliasee's aliasee. We also warn, since the user is probably
// expecting the link to be weak.
if (auto GA = dyn_cast<llvm::GlobalAlias>(AliaseeGV)) {
if (GA->mayBeOverridden()) {
Diags.Report(AA->getLocation(), diag::warn_alias_to_weak_alias)
<< GA->getAliasedGlobal()->getName() << GA->getName();
Aliasee = llvm::ConstantExpr::getPointerBitCastOrAddrSpaceCast(
GA->getAliasee(), Alias->getType());
Alias->setAliasee(Aliasee);
}
}
}
if (!Error)
return;
@@ -2246,6 +2218,29 @@ void CodeGenModule::EmitGlobalFunctionDefinition(GlobalDecl GD,
AddGlobalAnnotations(D, Fn);
}
static llvm::GlobalObject &getGlobalObjectInExpr(DiagnosticsEngine &Diags,
const AliasAttr *AA,
llvm::Constant *C) {
if (auto *GO = dyn_cast<llvm::GlobalObject>(C))
return *GO;
auto *GA = dyn_cast<llvm::GlobalAlias>(C);
if (GA) {
if (GA->mayBeOverridden()) {
Diags.Report(AA->getLocation(), diag::warn_alias_to_weak_alias)
<< GA->getAliasee()->getName() << GA->getName();
}
return *GA->getAliasee();
}
auto *CE = cast<llvm::ConstantExpr>(C);
assert(CE->getOpcode() == llvm::Instruction::BitCast ||
CE->getOpcode() == llvm::Instruction::GetElementPtr ||
CE->getOpcode() == llvm::Instruction::AddrSpaceCast);
return *cast<llvm::GlobalObject>(CE->getOperand(0));
}
void CodeGenModule::EmitAliasDefinition(GlobalDecl GD) {
const auto *D = cast<ValueDecl>(GD.getDecl());
const AliasAttr *AA = D->getAttr<AliasAttr>();
@@ -2276,9 +2271,15 @@ void CodeGenModule::EmitAliasDefinition(GlobalDecl GD) {
// Create the new alias itself, but don't set a name yet.
auto *GA = new llvm::GlobalAlias(
cast<llvm::PointerType>(Aliasee->getType())->getElementType(),
llvm::Function::ExternalLinkage, "", Aliasee, &getModule());
llvm::Function::ExternalLinkage, "",
&getGlobalObjectInExpr(Diags, AA, Aliasee), &getModule());
if (Entry) {
if (GA->getAliasee() == Entry) {
Diags.Report(AA->getLocation(), diag::err_cyclic_alias);
return;
}
assert(Entry->isDeclaration());
// If there is a declaration in the module, then we had an extern followed
@@ -3196,9 +3197,9 @@ void CodeGenModule::EmitStaticExternCAliases() {
IdentifierInfo *Name = I->first;
llvm::GlobalValue *Val = I->second;
if (Val && !getModule().getNamedValue(Name->getName()))
addUsedGlobal(new llvm::GlobalAlias(Val->getType()->getElementType(),
Val->getLinkage(), Name->getName(),
Val, &getModule()));
addUsedGlobal(new llvm::GlobalAlias(
Val->getType()->getElementType(), Val->getLinkage(), Name->getName(),
cast<llvm::GlobalObject>(Val), &getModule()));
}
}