[llvm-pdbdump] More advanced class definition dumping.

Previously the dumping of class definitions was very primitive,
and it made it hard to do more than the most trivial of output
formats when dumping.  As such, we would only dump one line for
each field, and then dump non-layout items like nested types
and enums.

With this patch, we do a complete analysis of the object
hierarchy including aggregate types, bases, virtual bases,
vftable analysis, etc.  The only immediately visible effects
of this are that a) we can now dump a line for the vfptr where
before we would treat that as padding, and b) we now don't
treat virtual bases that come at the end of a class as padding
since we have a more detailed analysis of the class's storage
usage.

In subsequent patches, we should be able to use this analysis
to display a complete graphical view of a class's layout including
recursing arbitrarily deep into an object's base class / aggregate
member hierarchy.

llvm-svn: 300133

1 files changed, 52 insertions, 79 deletions

diff --git a/llvm/tools/llvm-pdbdump/PrettyClassDefinitionDumper.cpp b/llvm/tools/llvm-pdbdump/PrettyClassDefinitionDumper.cpp
index b48ed23c1c7..2e1e54e4db1 100644
--- a/llvm/tools/llvm-pdbdump/PrettyClassDefinitionDumper.cpp
+++ b/llvm/tools/llvm-pdbdump/PrettyClassDefinitionDumper.cpp
@@ -28,7 +28,8 @@
 #include "llvm/DebugInfo/PDB/PDBSymbolTypeTypedef.h"
 #include "llvm/DebugInfo/PDB/PDBSymbolTypeUDT.h"
 #include "llvm/DebugInfo/PDB/PDBSymbolTypeVTable.h"
-#include "llvm/Support/Compiler.h"
+#include "llvm/DebugInfo/PDB/UDTLayout.h"
+
 #include "llvm/Support/Format.h"
 
 using namespace llvm;
@@ -37,58 +38,23 @@ using namespace llvm::pdb;
 ClassDefinitionDumper::ClassDefinitionDumper(LinePrinter &P)
     : PDBSymDumper(true), Printer(P) {}
 
-static void analyzePadding(const PDBSymbolTypeUDT &Class, BitVector &Padding,
-                           uint32_t &FirstFieldOffset) {
-  Padding.resize(Class.getLength(), true);
-  auto Children = Class.findAllChildren<PDBSymbolData>();
-  bool IsFirst = true;
-  FirstFieldOffset = Class.getLength();
-
-  while (auto Data = Children->getNext()) {
-    // Ignore data members which are not relative to this.  Usually these are
-    // static data members or constexpr and occupy no space.  We also need to
-    // handle BitFields since the PDB doesn't consider them ThisRel, but they
-    // still occupy space in the record layout.
-    auto LocType = Data->getLocationType();
-    if (LocType != PDB_LocType::ThisRel && LocType != PDB_LocType::BitField)
-      continue;
-
-    uint64_t Start = Data->getOffset();
-    if (IsFirst) {
-      FirstFieldOffset = Start;
-      IsFirst = false;
-    }
-
-    auto VarType = Data->getType();
-    uint64_t Size = VarType->getRawSymbol().getLength();
-    Padding.reset(Start, Start + Size);
-  }
-
-  // Unmark anything that comes before the first field so it doesn't get
-  // counted as padding.  In reality this is going to be vptrs or base class
-  // members, but we don't correctly handle that yet.
-  // FIXME: Handle it.
-  Padding.reset(0, FirstFieldOffset);
-}
-
 void ClassDefinitionDumper::start(const PDBSymbolTypeUDT &Class) {
   assert(opts::pretty::ClassFormat !=
          opts::pretty::ClassDefinitionFormat::None);
 
   uint32_t Size = Class.getLength();
-  uint32_t FirstFieldOffset = 0;
-  BitVector Padding;
-  analyzePadding(Class, Padding, FirstFieldOffset);
 
-  if (opts::pretty::OnlyPaddingClasses && (Padding.count() == 0))
+  ClassLayout Layout(Class.clone());
+
+  if (opts::pretty::OnlyPaddingClasses && (Layout.shallowPaddingSize() == 0))
     return;
 
   Printer.NewLine();
-  WithColor(Printer, PDB_ColorItem::Comment).get() << "// sizeof = " << Size;
-  Printer.NewLine();
 
   WithColor(Printer, PDB_ColorItem::Keyword).get() << Class.getUdtKind() << " ";
   WithColor(Printer, PDB_ColorItem::Type).get() << Class.getName();
+  WithColor(Printer, PDB_ColorItem::Comment).get() << " [sizeof = " << Size
+                                                   << "]";
 
   auto Bases = Class.findAllChildren<PDBSymbolTypeBaseClass>();
   if (Bases->getChildCount() > 0) {
@@ -111,60 +77,54 @@ void ClassDefinitionDumper::start(const PDBSymbolTypeUDT &Class) {
   }
 
   Printer << " {";
-  auto Children = Class.findAllChildren();
   Printer.Indent();
-  int DumpedCount = 0;
-
-  int NextPaddingByte = Padding.find_first();
-  while (auto Child = Children->getNext()) {
-    if (auto Data = llvm::dyn_cast<PDBSymbolData>(Child.get())) {
-      if (Data->getDataKind() == PDB_DataKind::Member && NextPaddingByte >= 0) {
-        // If there are padding bytes remaining, see if this field is the first
-        // to cross a padding boundary, and print a padding field indicator if
-        // so.
-        int Off = Data->getOffset();
-        if (Off > NextPaddingByte) {
-          uint32_t Amount = Off - NextPaddingByte;
-          Printer.NewLine();
-          WithColor(Printer, PDB_ColorItem::Padding).get()
-              << "<padding> (" << Amount << " bytes)";
-          assert(Padding.find_next_unset(NextPaddingByte) == Off);
-          NextPaddingByte = Padding.find_next(Off);
-        }
-      }
-    }
 
-    if (auto Func = Child->cast<PDBSymbolFunc>()) {
-      if (Func->isCompilerGenerated() && opts::pretty::ExcludeCompilerGenerated)
-        continue;
+  // Dump non-layout items first, but only if we're not in layout-only mode.
+  if (opts::pretty::ClassFormat !=
+      opts::pretty::ClassDefinitionFormat::Layout) {
+    for (auto &Other : Layout.other_items())
+      Other->dump(*this);
+  }
 
-      if (Func->getLength() == 0 && !Func->isPureVirtual() &&
-          !Func->isIntroVirtualFunction())
-        continue;
+  const BitVector &UseMap = Layout.usedBytes();
+  int NextUnusedByte = Layout.usedBytes().find_first_unset();
+  // Next dump items which affect class layout.
+  for (auto &LayoutItem : Layout.layout_items()) {
+    if (NextUnusedByte >= 0) {
+      // If there are padding bytes remaining, see if this field is the first to
+      // cross a padding boundary, and print a padding field indicator if so.
+      int Off = LayoutItem->getOffsetInParent();
+      if (Off > NextUnusedByte) {
+        uint32_t Amount = Off - NextUnusedByte;
+        Printer.NewLine();
+        WithColor(Printer, PDB_ColorItem::Padding).get() << "<padding> ("
+                                                         << Amount << " bytes)";
+        assert(UseMap.find_next(NextUnusedByte) == Off);
+        NextUnusedByte = UseMap.find_next_unset(Off);
+      }
     }
-
-    ++DumpedCount;
-    Child->dump(*this);
+    LayoutItem->getSymbol().dump(*this);
   }
 
-  if (NextPaddingByte >= 0) {
-    uint32_t Amount = Size - NextPaddingByte;
+  if (NextUnusedByte >= 0 && Layout.getClassSize() > 1) {
+    uint32_t Amount = Layout.getClassSize() - NextUnusedByte;
     Printer.NewLine();
     WithColor(Printer, PDB_ColorItem::Padding).get() << "<padding> (" << Amount
                                                      << " bytes)";
+    DumpedAnything = true;
   }
+
   Printer.Unindent();
-  if (DumpedCount > 0)
+  if (DumpedAnything)
     Printer.NewLine();
   Printer << "}";
   Printer.NewLine();
-  if (Padding.count() > 0) {
-    APFloat Pct(100.0 * (double)Padding.count() /
-                (double)(Size - FirstFieldOffset));
+  if (Layout.deepPaddingSize() > 0) {
+    APFloat Pct(100.0 * (double)Layout.deepPaddingSize() / (double)Size);
     SmallString<8> PctStr;
     Pct.toString(PctStr, 4);
     WithColor(Printer, PDB_ColorItem::Padding).get()
-        << "Total padding " << Padding.count() << " bytes (" << PctStr
+        << "Total padding " << Layout.deepPaddingSize() << " bytes (" << PctStr
         << "% of class size)";
     Printer.NewLine();
   }
@@ -175,23 +135,35 @@ void ClassDefinitionDumper::dump(const PDBSymbolTypeBaseClass &Symbol) {}
 void ClassDefinitionDumper::dump(const PDBSymbolData &Symbol) {
   VariableDumper Dumper(Printer);
   Dumper.start(Symbol);
+  DumpedAnything = true;
 }
 
 void ClassDefinitionDumper::dump(const PDBSymbolFunc &Symbol) {
   if (Printer.IsSymbolExcluded(Symbol.getName()))
     return;
+  if (Symbol.isCompilerGenerated() && opts::pretty::ExcludeCompilerGenerated)
+    return;
+  if (Symbol.getLength() == 0 && !Symbol.isPureVirtual() &&
+      !Symbol.isIntroVirtualFunction())
+    return;
 
+  DumpedAnything = true;
   Printer.NewLine();
   FunctionDumper Dumper(Printer);
   Dumper.start(Symbol, FunctionDumper::PointerType::None);
 }
 
-void ClassDefinitionDumper::dump(const PDBSymbolTypeVTable &Symbol) {}
+void ClassDefinitionDumper::dump(const PDBSymbolTypeVTable &Symbol) {
+  VariableDumper Dumper(Printer);
+  Dumper.start(Symbol);
+  DumpedAnything = true;
+}
 
 void ClassDefinitionDumper::dump(const PDBSymbolTypeEnum &Symbol) {
   if (Printer.IsTypeExcluded(Symbol.getName()))
     return;
 
+  DumpedAnything = true;
   Printer.NewLine();
   EnumDumper Dumper(Printer);
   Dumper.start(Symbol);
@@ -201,6 +173,7 @@ void ClassDefinitionDumper::dump(const PDBSymbolTypeTypedef &Symbol) {
   if (Printer.IsTypeExcluded(Symbol.getName()))
     return;
 
+  DumpedAnything = true;
   Printer.NewLine();
   TypedefDumper Dumper(Printer);
   Dumper.start(Symbol);