llvm-cov don't fail the entire invocation if one of the provided object doesn't contain coverage info

[eagleonhill]

Summary

It's common for an object to not contain any profilable function, e.g. constants only. We use relevant objects to filter the coverage instrumenation and support multi-processing.
some random non-profilable object could fail the entire invocation.

This will make llvm-cov ignore if any objects is empty, however it still fail if all of the provided objects are empty.

[vsk]

Thanks for the patch.

llvm/lib/ProfileData/Coverage/CoverageMapping.cpp

297

Could you please rebase this patch on top of r363325 (D63232)?

llvm/test/tools/llvm-cov/empty_object.test

1

Please check in the .o file instead of invoking clang, as it won't be available on the buildbots.

11

IIRC the syntax for expected-to-fail RUN commands is 'not <command>'.

[vsk]

(Marking this to reflect my comment from 5/24 to clear my review queue)

llvm/lib/ProfileData/Coverage/CoverageMapping.cpp

CoverageMapping::load(ArrayRef<StringRef> ObjectFilenames,
   SmallVector<std::unique_ptr<MemoryBuffer>, 4> Buffers;
   for (const auto &File : llvm::enumerate(ObjectFilenames)) {
     auto CovMappingBufOrErr = MemoryBuffer::getFileOrSTDIN(File.value());
     if (std::error_code EC = CovMappingBufOrErr.getError())
       return errorCodeToError(EC);
     StringRef Arch = Arches.empty() ? StringRef() : Arches[File.index()];
     auto CoverageReaderOrErr =
         BinaryCoverageReader::create(CovMappingBufOrErr.get(), Arch);
-    if (Error E = CoverageReaderOrErr.takeError())
+    if (Error E = CoverageReaderOrErr.takeError()) {
+      E = handleErrors(std::move(E),
+                       [&](std::unique_ptr<CoverageMapError> CME) -> Error {
+                         if (CME->get() == coveragemap_error::no_data_found)
+                           return Error::success();
+                         return Error(std::move(CME));
+                       });
+      if (E) {
         return std::move(E);
+      }
+    } else {
       Readers.push_back(std::move(CoverageReaderOrErr.get()));
       Buffers.push_back(std::move(CovMappingBufOrErr.get()));
     }
+  }
+  if (Readers.empty()) {
+    return make_error<CoverageMapError>(coveragemap_error::no_data_found);
+  }
   return load(Readers, *ProfileReader);
 }
 
 namespace {
 
 /// Distributes functions into instantiation sets.
 ///
 /// An instantiation set is a collection of functions that have the same source

llvm/test/tools/llvm-cov/Inputs/empty_object/empty_object.cc

+const int foo = 1;

llvm/test/tools/llvm-cov/Inputs/empty_object/main.cc

+int main() {}

llvm/test/tools/llvm-cov/empty_object.test

+RUN: clang -std=c++11 -mllvm -enable-name-compression=false -fprofile-instr-generate -fcoverage-mapping %S/Inputs/empty_object/empty_object.cc -c -o %t.o
+
+It shouldn't fail if other valid object is provided.
+RUN: llvm-cov report -instr-profile %S/Inputs/empty_object/merged.profdata \
+RUN:   -object %S/Inputs/empty_object/main.covmapping \
+RUN:   -object %t.o | FileCheck -check-prefix=REPORT %s
+
+REPORT: main.cc
+
+It should still fail if no other valid object is provided.
+RUN: (! llvm-cov report -instr-profile %S/Inputs/empty_object/merged.profdata \
+RUN:   -object %t.o) 2>&1 | FileCheck -check-prefix=FAIL %s
+FAIL: No coverage data found
+
+Instructions for regenerating the test:
+
+clang -std=c++11 -mllvm -enable-name-compression=false -fprofile-instr-generate -fcoverage-mapping main.cc -o main
+LLVM_PROFILE_FILE="main.raw" ./main
+llvm-profdata merge main.raw -o merged.profdata
+llvm-cov convert-for-testing ./main -o ./main.covmapping