[CodeView] Don't output S_UDT symbols for forward decls.
S_UDT symbols are the debugger's "index" for all the structs,
typedefs, classes, and enums in a program. If any of those
structs/classes don't have a complete declaration, or if there
is a typedef to something that doesn't have a complete definition,
then emitting the S_UDT is unhelpful because it doesn't give
the debugger enough information to do anything useful. On the
other hand, it results in a huge size blow-up in the resulting
PDB, which is exacerbated by an order of magnitude when linking
with /DEBUG:FASTLINK.
With this patch, we drop S_UDT records for types that refer either
directly or indirectly (e.g. through a typedef, pointer, etc) to
a class/struct/union/enum without a complete definition. This
brings us about 50% of the way towards parity with /DEBUG:FASTLINK
PDBs generated from cl-compiled object files.
Differential Revision: https://reviews.llvm.org/D37162
llvm-svn: 311904
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index 4346803..8879f6b1 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -1099,10 +1099,25 @@
}
}
-void CodeViewDebug::addToUDTs(const DIType *Ty, TypeIndex TI) {
+static bool shouldEmitUdt(const DIType *T) {
+ while (true) {
+ if (!T || T->isForwardDecl())
+ return false;
+
+ const DIDerivedType *DT = dyn_cast<DIDerivedType>(T);
+ if (!DT)
+ return true;
+ T = DT->getBaseType().resolve();
+ }
+ return true;
+}
+
+void CodeViewDebug::addToUDTs(const DIType *Ty) {
// Don't record empty UDTs.
if (Ty->getName().empty())
return;
+ if (!shouldEmitUdt(Ty))
+ return;
SmallVector<StringRef, 5> QualifiedNameComponents;
const DISubprogram *ClosestSubprogram = getQualifiedNameComponents(
@@ -1111,10 +1126,11 @@
std::string FullyQualifiedName =
getQualifiedName(QualifiedNameComponents, getPrettyScopeName(Ty));
- if (ClosestSubprogram == nullptr)
- GlobalUDTs.emplace_back(std::move(FullyQualifiedName), TI);
- else if (ClosestSubprogram == CurrentSubprogram)
- LocalUDTs.emplace_back(std::move(FullyQualifiedName), TI);
+ if (ClosestSubprogram == nullptr) {
+ GlobalUDTs.emplace_back(std::move(FullyQualifiedName), Ty);
+ } else if (ClosestSubprogram == CurrentSubprogram) {
+ LocalUDTs.emplace_back(std::move(FullyQualifiedName), Ty);
+ }
// TODO: What if the ClosestSubprogram is neither null or the current
// subprogram? Currently, the UDT just gets dropped on the floor.
@@ -1172,7 +1188,7 @@
TypeIndex UnderlyingTypeIndex = getTypeIndex(UnderlyingTypeRef);
StringRef TypeName = Ty->getName();
- addToUDTs(Ty, UnderlyingTypeIndex);
+ addToUDTs(Ty);
if (UnderlyingTypeIndex == TypeIndex(SimpleTypeKind::Int32Long) &&
TypeName == "HRESULT")
@@ -1764,7 +1780,7 @@
TypeTable.writeKnownType(USLR);
}
- addToUDTs(Ty, ClassTI);
+ addToUDTs(Ty);
return ClassTI;
}
@@ -1803,7 +1819,7 @@
UdtSourceLineRecord USLR(UnionTI, SIRI, Ty->getLine());
TypeTable.writeKnownType(USLR);
- addToUDTs(Ty, UnionTI);
+ addToUDTs(Ty);
return UnionTI;
}
@@ -2203,8 +2219,11 @@
}
void CodeViewDebug::emitDebugInfoForUDTs(
- ArrayRef<std::pair<std::string, TypeIndex>> UDTs) {
- for (const std::pair<std::string, codeview::TypeIndex> &UDT : UDTs) {
+ ArrayRef<std::pair<std::string, const DIType *>> UDTs) {
+ for (const auto &UDT : UDTs) {
+ const DIType *T = UDT.second;
+ assert(shouldEmitUdt(T));
+
MCSymbol *UDTRecordBegin = MMI->getContext().createTempSymbol(),
*UDTRecordEnd = MMI->getContext().createTempSymbol();
OS.AddComment("Record length");
@@ -2215,7 +2234,7 @@
OS.EmitIntValue(unsigned(SymbolKind::S_UDT), 2);
OS.AddComment("Type");
- OS.EmitIntValue(UDT.second.getIndex(), 4);
+ OS.EmitIntValue(getCompleteTypeIndex(T).getIndex(), 4);
emitNullTerminatedSymbolName(OS, UDT.first);
OS.EmitLabel(UDTRecordEnd);