[llvm-cov] Add lcov tracefile export format.

Summary:
lcov tracefiles are used by various coverage reporting tools and build
systems (e.g., Bazel). It is a simple text-based format to parse and
more convenient to use than the JSON export format, which needs
additional processing to map regions/segments back to line numbers.

It's a little unfortunate that "text" format is now overloaded to refer
specifically to JSON for export, but I wanted to avoid making any
breaking changes to the UI of the llvm-cov tool at this time.

Patch by Tony Allevato (@allevato).

Reviewers: Dor1s, vsk

Reviewed By: Dor1s, vsk

Subscribers: mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D54266

llvm-svn: 346506

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/tools/llvm-cov/SourceCoverageView.cpp b/llvm/tools/llvm-cov/SourceCoverageView.cpp
index a5a8fa9..775322b 100644
--- a/llvm/tools/llvm-cov/SourceCoverageView.cpp
+++ b/llvm/tools/llvm-cov/SourceCoverageView.cpp
@@ -80,6 +80,10 @@ CoveragePrinter::create(const CoverageViewOptions &Opts) {
     return llvm::make_unique<CoveragePrinterText>(Opts);
   case CoverageViewOptions::OutputFormat::HTML:
     return llvm::make_unique<CoveragePrinterHTML>(Opts);
+  case CoverageViewOptions::OutputFormat::Lcov:
+    // Unreachable because CodeCoverage.cpp should terminate with an error
+    // before we get here.
+    llvm_unreachable("Lcov format is not supported!");
   }
   llvm_unreachable("Unknown coverage output format!");
 }
@@ -143,6 +147,10 @@ SourceCoverageView::create(StringRef SourceName, const MemoryBuffer &File,
   case CoverageViewOptions::OutputFormat::HTML:
     return llvm::make_unique<SourceCoverageViewHTML>(
         SourceName, File, Options, std::move(CoverageInfo));
+  case CoverageViewOptions::OutputFormat::Lcov:
+    // Unreachable because CodeCoverage.cpp should terminate with an error
+    // before we get here.
+    llvm_unreachable("Lcov format is not supported!");
   }
   llvm_unreachable("Unknown coverage output format!");
 }