DWARFAcceleratorTable: fix equal_range iterators

Summary:
Both (Apple and DWARF5) implementations of the iterators had bugs which
resulted in crashes if one attempted to iterate through the accelerator
tables all the way.

For the Apple tables, the issue was that we did not clear the DataOffset
field when we reached the end, which made our iterator compare unequal
to the "end" iterator. For the Dwarf5 tables, the problem was that we
incremented the CurrentIndex pointer and then used the incremented
(possibly invalid) pointer to check whether we have reached the end of
the index list.

The reason these bugs went undetected is because their only user
(dwarfdump) only ever searched for the first match. Besides allowing us
to test this fix, changing llvm-dwarfdump --find to display all matches
seems like a good improvement (it makes the behavior consistent with the
--name option), so I change llvm-dwarfdump to do that.

The existing tests would be sufficient to test this fix with the new
llvm-dwarfdump behavior, but I add a special test that demonstrates that
the tool indeed displays multiple results. The find.test test needed to
be tweaked a bit as the tool now does not print the ".debug_info
contents" header (also consistent with how --name works).

Reviewers: JDevlieghere, aprantl, dblaikie

Subscribers: mgrang, llvm-commits

Differential Revision: https://reviews.llvm.org/D47543

llvm-svn: 333635

1 files changed, 29 insertions, 25 deletions

diff --git a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
index 300a00b01be..433c681a108 100644
--- a/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
+++ b/llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp
@@ -309,6 +309,33 @@ static void filterByName(const StringSet<> &Names,
 
 }
 
+template <typename AccelTable>
+static void getDIEOffset(const AccelTable &Accel, StringRef Name,
+                         SmallVectorImpl<uint64_t> &Offsets) {
+  for (const auto &Entry : Accel.equal_range(Name))
+    if (llvm::Optional<uint64_t> Off = Entry.getDIESectionOffset())
+      Offsets.push_back(*Off);
+}
+
+/// Print only DIEs that have a certain name.
+static void filterByAccelName(ArrayRef<std::string> Names, DWARFContext &DICtx,
+                              raw_ostream &OS) {
+  SmallVector<uint64_t, 4> Offsets;
+  for (const auto &Name : Names) {
+    getDIEOffset(DICtx.getAppleNames(), Name, Offsets);
+    getDIEOffset(DICtx.getAppleTypes(), Name, Offsets);
+    getDIEOffset(DICtx.getAppleNamespaces(), Name, Offsets);
+    getDIEOffset(DICtx.getDebugNames(), Name, Offsets);
+  }
+  llvm::sort(Offsets.begin(), Offsets.end());
+  Offsets.erase(std::unique(Offsets.begin(), Offsets.end()), Offsets.end());
+
+  for (uint64_t Off: Offsets) {
+    DWARFDie Die = DICtx.getDIEForOffset(Off);
+    Die.dump(OS, 0, getDumpOpts());
+  }
+}
+
 /// Handle the --lookup option and dump the DIEs and line info for the given
 /// address.
 static bool lookup(DWARFContext &DICtx, uint64_t Address, raw_ostream &OS) {
@@ -335,15 +362,6 @@ static bool lookup(DWARFContext &DICtx, uint64_t Address, raw_ostream &OS) {
 bool collectStatsForObjectFile(ObjectFile &Obj, DWARFContext &DICtx,
                                Twine Filename, raw_ostream &OS);
 
-template <typename AccelTable>
-static llvm::Optional<uint64_t> getDIEOffset(const AccelTable &Accel,
-                                       StringRef Name) {
-  for (const auto &Entry : Accel.equal_range(Name))
-    if (llvm::Optional<uint64_t> Off = Entry.getDIESectionOffset())
-      return *Off;
-  return None;
-}
-
 static bool dumpObjectFile(ObjectFile &Obj, DWARFContext &DICtx, Twine Filename,
                            raw_ostream &OS) {
   logAllUnhandledErrors(DICtx.loadRegisterInfo(Obj), errs(),
@@ -369,22 +387,8 @@ static bool dumpObjectFile(ObjectFile &Obj, DWARFContext &DICtx, Twine Filename,
 
   // Handle the --find option and lower it to --debug-info=<offset>.
   if (!Find.empty()) {
-    DumpOffsets[DIDT_ID_DebugInfo] = [&]() -> llvm::Optional<uint64_t> {
-      for (auto Name : Find) {
-        if (auto Offset = getDIEOffset(DICtx.getAppleNames(), Name))
-          return DumpOffsets[DIDT_ID_DebugInfo] = *Offset;
-        if (auto Offset = getDIEOffset(DICtx.getAppleTypes(), Name))
-          return DumpOffsets[DIDT_ID_DebugInfo] = *Offset;
-        if (auto Offset = getDIEOffset(DICtx.getAppleNamespaces(), Name))
-          return DumpOffsets[DIDT_ID_DebugInfo] = *Offset;
-        if (auto Offset = getDIEOffset(DICtx.getDebugNames(), Name))
-          return DumpOffsets[DIDT_ID_DebugInfo] = *Offset;
-      }
-      return None;
-    }();
-    // Early exit if --find was specified but the current file doesn't have it.
-    if (!DumpOffsets[DIDT_ID_DebugInfo])
-      return true;
+    filterByAccelName(Find, DICtx, OS);
+    return true;
   }
 
   // Dump the complete DWARF structure.