[Coverage] Add an API to retrive all instantiations of a function (NFC)

The CoverageMapping::getInstantiations() API retrieved all function
records corresponding to functions with more than one instantiation (e.g
template functions with multiple specializations). However, there was no
simple way to determine *which* function a given record was an
instantiation of. This was an oversight, since it's useful to aggregate
coverage information over all instantiations of a function.

llvm-cov works around this by building a mapping of source locations to
instantiation sets, but this duplicates logic that libCoverage already
has (see FunctionInstantiationSetCollector).

This change adds a new API, CoverageMapping::getInstantiationGroups(),
which returns a list of InstantiationGroups. A group contains records
for each instantiation of some particular function, and also provides
utilities to get the total execution count within the group, the source
location of the common definition, etc.

This lets removes some hacky logic in llvm-cov by reusing
FunctionInstantiationSetCollector and makes the CoverageMapping API
friendlier for other clients.

llvm-svn: 309904

1 files changed, 6 insertions, 4 deletions

diff --git a/llvm/tools/llvm-cov/CoverageSummaryInfo.h b/llvm/tools/llvm-cov/CoverageSummaryInfo.h
index 680fc37..1603731 100644
--- a/llvm/tools/llvm-cov/CoverageSummaryInfo.h
+++ b/llvm/tools/llvm-cov/CoverageSummaryInfo.h
@@ -115,7 +115,7 @@ struct FunctionCoverageInfo {
 
 /// \brief A summary of function's code coverage.
 struct FunctionCoverageSummary {
-  StringRef Name;
+  std::string Name;
   uint64_t ExecutionCount;
   RegionCoverageInfo RegionCoverage;
   LineCoverageInfo LineCoverage;
@@ -134,9 +134,11 @@ struct FunctionCoverageSummary {
   static FunctionCoverageSummary
   get(const coverage::FunctionRecord &Function);
 
-  /// \brief Update the summary with information from another instantiation
-  /// of this function.
-  void update(const FunctionCoverageSummary &Summary);
+  /// Compute the code coverage summary for an instantiation group \p Group,
+  /// given a list of summaries for each instantiation in \p Summaries.
+  static FunctionCoverageSummary
+  get(const coverage::InstantiationGroup &Group,
+      ArrayRef<FunctionCoverageSummary> Summaries);
 };
 
 /// \brief A summary of file's code coverage.