Aggregate errors from llvm-dwarfdump --verify (#79648)

The amount and format of output from `llvm-dwarfdump --verify` makes it
quite difficult to know if a change to a tool that produces or modifies
DWARF is causing new problems, or is fixing existing problems. This diff
adds a categorized summary of issues found by the DWARF verifier, on by
default, at the bottom of the error output.

The change includes a new `--error-display` option with 4 settings:

* `--error-display=quiet`: Only display if errors occurred, but no
details or summary are printed.
* `--error-display=summary`: Only display the aggregated summary of
errors with no error detail.
* `--error-display=details`: Only display the detailed error messages
with no summary (previous behavior)
* `--error-display=full`: Display both the detailed error messages and
the aggregated summary of errors (the default)

I changed a handful of tests that were failing due to new output, adding
the flag to use the old behavior for all but a couple. For those two I
added the new aggregated output to the expected output of the test.

The `OutputCategoryAggregator` is a pretty simple little class that
@clayborg suggested to allow code to only be run to dump detail if it's
enabled, while still collating counts of the category. Knowing that the
lambda passed in is only conditionally executed is pretty important
(handling errors has to be done *outside* the lambda). I'm happy to move
this somewhere else (and change/improve it) to be more broadly useful if
folks would like.

---------

Co-authored-by: Kevin Frei <[email protected]>

Author: kevinfrei

llvm/include/llvm/DebugInfo/DIContext.h

@@ -205,6 +205,7 @@ struct DIDumpOptions {
   bool DisplayRawContents = false;
   bool IsEH = false;
   bool DumpNonSkeleton = false;
+  bool ShowAggregateErrors = false;
   std::function<llvm::StringRef(uint64_t DwarfRegNum, bool IsEH)>
       GetNameForDWARFReg;
 

llvm/include/llvm/DebugInfo/DWARF/DWARFVerifier.h

@@ -30,6 +30,20 @@ class DWARFDebugAbbrev;
 class DataExtractor;
 struct DWARFSection;
 
+class OutputCategoryAggregator {
+private:
+  std::map<std::string, unsigned> Aggregation;
+  bool IncludeDetail;
+
+public:
+  OutputCategoryAggregator(bool includeDetail = false)
+      : IncludeDetail(includeDetail) {}
+  void ShowDetail(bool showDetail) { IncludeDetail = showDetail; }
+  size_t GetNumCategories() const { return Aggregation.size(); }
+  void Report(StringRef s, std::function<void()> detailCallback);
+  void EnumerateResults(std::function<void(StringRef, unsigned)> handleCounts);
+};
+
 /// A class that verifies DWARF debug information given a DWARF Context.
 class DWARFVerifier {
 public:
@@ -81,6 +95,7 @@ class DWARFVerifier {
   DWARFContext &DCtx;
   DIDumpOptions DumpOpts;
   uint32_t NumDebugLineErrors = 0;
+  OutputCategoryAggregator ErrorCategory;
   // Used to relax some checks that do not currently work portably
   bool IsObjectFile;
   bool IsMachOObject;
@@ -348,6 +363,9 @@ class DWARFVerifier {
   bool verifyDebugStrOffsets(
       StringRef SectionName, const DWARFSection &Section, StringRef StrData,
       void (DWARFObject::*)(function_ref<void(const DWARFSection &)>) const);
+
+  /// Emits any aggregate information collected, depending on the dump options
+  void summarize();
 };
 
 static inline bool operator<(const DWARFVerifier::DieRangeInfo &LHS,

llvm/lib/DebugInfo/DWARF/DWARFContext.cpp

@@ -1408,6 +1408,7 @@ bool DWARFContext::verify(raw_ostream &OS, DIDumpOptions DumpOpts) {
   if (DumpOpts.DumpType & DIDT_DebugStrOffsets)
     Success &= verifier.handleDebugStrOffsets();
   Success &= verifier.handleAccelTables();
+  verifier.summarize();
   return Success;
 }