caio/clang-p2996
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[IR] Don't allow DLL storage-class and local linkage

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Disallow this meaningless combination. Doing so simplifies analysis
of LLVM code w.r.t t DLL storage-class, and prevents mistakes with
DLL storage class.

- Change the assembler to reject DLL storage class on symbols with
  local linkage.
- Change the bitcode reader to clear the DLL Storage class when the
  linkage is local for auto-upgrading
- Update LangRef.

There is an existing restriction on non-default visibility and local
linkage which this is modelled on.

Differential Review: https://reviews.llvm.org/D134784
This commit is contained in:
Ben Dunbobbin
2022-09-30 00:21:31 +01:00
parent 0bfaa301e2
commit 7eee2a2d44
7 changed files with 147 additions and 16 deletions
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31
llvm/lib/Bitcode/Reader/BitcodeReader.cpp
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@@ -1298,6 +1298,9 @@ static FastMathFlags getDecodedFastMathFlags(unsigned Val) {
}
static void upgradeDLLImportExportLinkage(GlobalValue *GV, unsigned Val) {
// A GlobalValue with local linkage cannot have a DLL storage class.
if (GV->hasLocalLinkage())
return;
switch (Val) {
case 5: GV->setDLLStorageClass(GlobalValue::DLLImportStorageClass); break;
case 6: GV->setDLLStorageClass(GlobalValue::DLLExportStorageClass); break;
@@ -3764,10 +3767,14 @@ Error BitcodeReader::parseGlobalVarRecord(ArrayRef<uint64_t> Record) {
NewGV->setVisibility(Visibility);
NewGV->setUnnamedAddr(UnnamedAddr);
if (Record.size() > 10)
NewGV->setDLLStorageClass(getDecodedDLLStorageClass(Record[10]));
else
if (Record.size() > 10) {
// A GlobalValue with local linkage cannot have a DLL storage class.
if (!NewGV->hasLocalLinkage()) {
NewGV->setDLLStorageClass(getDecodedDLLStorageClass(Record[10]));
}
} else {
upgradeDLLImportExportLinkage(NewGV, RawLinkage);
}
ValueList.push_back(NewGV, getVirtualTypeID(NewGV->getType(), TyID));
@@ -3928,10 +3935,14 @@ Error BitcodeReader::parseFunctionRecord(ArrayRef<uint64_t> Record) {
if (Record.size() > 10)
OperandInfo.Prologue = Record[10];
if (Record.size() > 11)
Func->setDLLStorageClass(getDecodedDLLStorageClass(Record[11]));
else
if (Record.size() > 11) {
// A GlobalValue with local linkage cannot have a DLL storage class.
if (!Func->hasLocalLinkage()) {
Func->setDLLStorageClass(getDecodedDLLStorageClass(Record[11]));
}
} else {
upgradeDLLImportExportLinkage(Func, RawLinkage);
}
if (Record.size() > 12) {
if (unsigned ComdatID = Record[12]) {
@@ -4034,8 +4045,12 @@ Error BitcodeReader::parseGlobalIndirectSymbolRecord(
}
if (BitCode == bitc::MODULE_CODE_ALIAS ||
BitCode == bitc::MODULE_CODE_ALIAS_OLD) {
if (OpNum != Record.size())
NewGA->setDLLStorageClass(getDecodedDLLStorageClass(Record[OpNum++]));
if (OpNum != Record.size()) {
auto S = Record[OpNum++];
// A GlobalValue with local linkage cannot have a DLL storage class.
if (!NewGA->hasLocalLinkage())
NewGA->setDLLStorageClass(getDecodedDLLStorageClass(S));
}
else
upgradeDLLImportExportLinkage(NewGA, Linkage);
if (OpNum != Record.size())