llvm-dwarfdump --verify aggregated output to JSON file (#81762)

In order to make tooling around dwarf health easier, I've added an `--verify-json` option to `llvm-dwarfdump --verify` that will spit out error summary data with counts to a JSON file.

I've added the same capability to `llvm-gsymutil` in a [different PR.](#81763)

The format of the json is:
``` json
{ 
  "error-categories": { 
    "<first category description>": {"count": 1234},
    "<next category description>": {"count":4321}
  },
  "error-count": 5555
}
```
for a clean run:
``` json
{ 
  "error-categories": {},
  "error-count": 0
}
```

---------

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

Author: kevinfrei

llvm/include/llvm/DebugInfo/DIContext.h

@@ -206,6 +206,7 @@ struct DIDumpOptions {
   bool IsEH = false;
   bool DumpNonSkeleton = false;
   bool ShowAggregateErrors = false;
+  std::string JsonErrSummaryFile;
   std::function<llvm::StringRef(uint64_t DwarfRegNum, bool IsEH)>
       GetNameForDWARFReg;
 

llvm/lib/DebugInfo/DWARF/DWARFVerifier.cpp

@@ -29,7 +29,9 @@
 #include "llvm/Support/DJB.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/FileSystem.h"
 #include "llvm/Support/FormatVariadic.h"
+#include "llvm/Support/JSON.h"
 #include "llvm/Support/WithColor.h"
 #include "llvm/Support/raw_ostream.h"
 #include <map>
@@ -2026,12 +2028,37 @@ void OutputCategoryAggregator::EnumerateResults(
 }
 
 void DWARFVerifier::summarize() {
-  if (ErrorCategory.GetNumCategories() && DumpOpts.ShowAggregateErrors) {
+  if (DumpOpts.ShowAggregateErrors && ErrorCategory.GetNumCategories()) {
     error() << "Aggregated error counts:\n";
     ErrorCategory.EnumerateResults([&](StringRef s, unsigned count) {
       error() << s << " occurred " << count << " time(s).\n";
     });
   }
+  if (!DumpOpts.JsonErrSummaryFile.empty()) {
+    std::error_code EC;
+    raw_fd_ostream JsonStream(DumpOpts.JsonErrSummaryFile, EC,
+                              sys::fs::OF_Text);
+    if (EC) {
+      error() << "unable to open json summary file '"
+              << DumpOpts.JsonErrSummaryFile
+              << "' for writing: " << EC.message() << '\n';
+      return;
+    }
+
+    llvm::json::Object Categories;
+    uint64_t ErrorCount = 0;
+    ErrorCategory.EnumerateResults([&](StringRef Category, unsigned Count) {
+      llvm::json::Object Val;
+      Val.try_emplace("count", Count);
+      Categories.try_emplace(Category, std::move(Val));
+      ErrorCount += Count;
+    });
+    llvm::json::Object RootNode;
+    RootNode.try_emplace("error-categories", std::move(Categories));
+    RootNode.try_emplace("error-count", ErrorCount);
+
+    JsonStream << llvm::json::Value(std::move(RootNode));
+  }
 }
 
 raw_ostream &DWARFVerifier::error() const { return WithColor::error(OS); }

llvm/tools/llvm-dwarfdump/llvm-dwarfdump.cpp

@@ -286,6 +286,8 @@ static opt<bool> Verify("verify", desc("Verify the DWARF debug info."),
                         cat(DwarfDumpCategory));
 static opt<ErrorDetailLevel> ErrorDetails(
     "error-display", init(Unspecified),
+    desc("Set the level of detail and summary to display when verifying "
+         "(implies --verify)"),
     values(clEnumValN(NoDetailsOrSummary, "quiet",
                       "Only display whether errors occurred."),
            clEnumValN(NoDetailsOnlySummary, "summary",
@@ -295,6 +297,11 @@ static opt<ErrorDetailLevel> ErrorDetails(
            clEnumValN(BothDetailsAndSummary, "full",
                       "Display each error as well as a summary. [default]")),
     cat(DwarfDumpCategory));
+static opt<std::string> JsonErrSummaryFile(
+    "verify-json", init(""),
+    desc("Output JSON-formatted error summary to the specified file. "
+         "(Implies --verify)"),
+    value_desc("filename.json"), cat(DwarfDumpCategory));
 static opt<bool> Quiet("quiet", desc("Use with -verify to not emit to STDOUT."),
                        cat(DwarfDumpCategory));
 static opt<bool> DumpUUID("uuid", desc("Show the UUID for each architecture."),
@@ -349,6 +356,7 @@ static DIDumpOptions getDumpOpts(DWARFContext &C) {
                        ErrorDetails != NoDetailsOrSummary;
     DumpOpts.ShowAggregateErrors = ErrorDetails != OnlyDetailsNoSummary &&
                                    ErrorDetails != NoDetailsOnlySummary;
+    DumpOpts.JsonErrSummaryFile = JsonErrSummaryFile;
     return DumpOpts.noImplicitRecursion();
   }
   return DumpOpts;
@@ -834,8 +842,10 @@ int main(int argc, char **argv) {
                           "-verbose is currently not supported";
     return 1;
   }
-  if (!Verify && ErrorDetails != Unspecified)
-    WithColor::warning() << "-error-detail has no affect without -verify";
+  // -error-detail and -json-summary-file both imply -verify
+  if (ErrorDetails != Unspecified || !JsonErrSummaryFile.empty()) {
+    Verify = true;
+  }
 
   std::error_code EC;
   ToolOutputFile OutputFile(OutputFilename, EC, sys::fs::OF_TextWithCRLF);