[dwarf] Unify unknown dwarf enum formatting code

Summary:
We have had at least three pieces of code (in DWARFAbbreviationDeclaration,
DWARFAcceleratorTable and DWARFDie) that have hand-rolled support for
dumping unknown dwarf enum values. While not terrible, they are a bit
distracting and enable small differences to creep in (Unknown_ffff vs.
Unknown_0xffff). I ended up needing to add a fourth place
(DWARFVerifier), so it seems it would be a good time to centralize.

This patch creates an alternative to the XXXString dumping functions in
the BinaryFormat library, which formats an unknown value as
DW_TYPE_unknown_1234, instead of just an empty string. It is based on
the formatv function, as that allows us to avoid materializing the
string for unknown values (and because this way I don't have to invent a
name for the new functions :P).

In this patch I add formatters for dwarf attributes, forms, tags, and
index attributes as these are the ones in use currently, but adding
other enums is straight-forward.

Reviewers: dblaikie, JDevlieghere, aprantl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D44570

llvm-svn: 328090

1 files changed, 12 insertions, 30 deletions

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp b/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
index 2bde3d6d034..3b9662067c3 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
@@ -15,6 +15,7 @@
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/DJB.h"
 #include "llvm/Support/Format.h"
+#include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cstddef>
@@ -24,35 +25,19 @@
 using namespace llvm;
 
 namespace {
-struct DwarfConstant {
-  StringRef (*StringFn)(unsigned);
-  StringRef Type;
+struct Atom {
   unsigned Value;
 };
 
-static raw_ostream &operator<<(raw_ostream &OS, const DwarfConstant &C) {
-  StringRef Str = C.StringFn(C.Value);
+static raw_ostream &operator<<(raw_ostream &OS, const Atom &A) {
+  StringRef Str = dwarf::AtomTypeString(A.Value);
   if (!Str.empty())
     return OS << Str;
-  return OS << "DW_" << C.Type << "_Unknown_0x" << format("%x", C.Value);
+  return OS << "DW_ATOM_unknown_" << format("%x", A.Value);
 }
 } // namespace
 
-static DwarfConstant formatTag(unsigned Tag) {
-  return {dwarf::TagString, "TAG", Tag};
-}
-
-static DwarfConstant formatForm(unsigned Form) {
-  return {dwarf::FormEncodingString, "FORM", Form};
-}
-
-static DwarfConstant formatIndex(unsigned Idx) {
-  return {dwarf::IndexString, "IDX", Idx};
-}
-
-static DwarfConstant formatAtom(unsigned Atom) {
-  return {dwarf::AtomTypeString, "ATOM", Atom};
-}
+static Atom formatAtom(unsigned Atom) { return {Atom}; }
 
 DWARFAcceleratorTable::~DWARFAcceleratorTable() = default;
 
@@ -226,7 +211,7 @@ LLVM_DUMP_METHOD void AppleAcceleratorTable::dump(raw_ostream &OS) const {
     for (const auto &Atom : HdrData.Atoms) {
       DictScope AtomScope(W, ("Atom " + Twine(i++)).str());
       W.startLine() << "Type: " << formatAtom(Atom.first) << '\n';
-      W.startLine() << "Form: " << formatForm(Atom.second) << '\n';
+      W.startLine() << "Form: " << formatv("{0}", Atom.second) << '\n';
       AtomForms.push_back(DWARFFormValue(Atom.second));
     }
   }
@@ -415,12 +400,10 @@ llvm::Error DWARFDebugNames::Header::extract(const DWARFDataExtractor &AS,
 
 void DWARFDebugNames::Abbrev::dump(ScopedPrinter &W) const {
   DictScope AbbrevScope(W, ("Abbreviation 0x" + Twine::utohexstr(Code)).str());
-  W.startLine() << "Tag: " << formatTag(Tag) << '\n';
+  W.startLine() << formatv("Tag: {0}\n", Tag);
 
-  for (const auto &Attr : Attributes) {
-    W.startLine() << formatIndex(Attr.Index) << ": " << formatForm(Attr.Form)
-                  << '\n';
-  }
+  for (const auto &Attr : Attributes)
+    W.startLine() << formatv("{0}: {1}\n", Attr.Index, Attr.Form);
 }
 
 static constexpr DWARFDebugNames::AttributeEncoding sentinelAttrEnc() {
@@ -583,11 +566,10 @@ Optional<uint64_t> DWARFDebugNames::Entry::getDIESectionOffset() const {
 
 void DWARFDebugNames::Entry::dump(ScopedPrinter &W) const {
   W.printHex("Abbrev", Abbr->Code);
-  W.startLine() << "Tag: " << formatTag(Abbr->Tag) << "\n";
-
+  W.startLine() << formatv("Tag: {0}\n", Abbr->Tag);
   assert(Abbr->Attributes.size() == Values.size());
   for (const auto &Tuple : zip_first(Abbr->Attributes, Values)) {
-    W.startLine() << formatIndex(std::get<0>(Tuple).Index) << ": ";
+    W.startLine() << formatv("{0}: ", std::get<0>(Tuple).Index);
     std::get<1>(Tuple).dump(W.getOStream());
     W.getOStream() << '\n';
   }