[Coverage] Take filenames into account when loading function records.

Summary:
Don't skip functions with the same name but from different files.

That change makes it possible to generate code coverage reports from
different binaries compiled from different sources even if there are functions
with non-unique names. Without that change, code coverage for such functions is
missing except of the first function processed.

Reviewers: vsk, morehouse

Reviewed By: vsk

Subscribers: llvm-commits, kcc

Differential Revision: https://reviews.llvm.org/D46478

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@331801 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit c97ab8f)

Author: Dor1s

include/llvm/ProfileData/Coverage/CoverageMapping.h

@@ -17,6 +17,7 @@
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/StringRef.h"
@@ -506,7 +507,7 @@ class CoverageData {
 /// This is the main interface to get coverage information, using a profile to
 /// fill out execution counts.
 class CoverageMapping {
-  StringSet<> FunctionNames;
+  DenseMap<size_t, DenseSet<size_t>> RecordProvenance;
   std::vector<FunctionRecord> Functions;
   std::vector<std::pair<std::string, uint64_t>> FuncHashMismatches;
   std::vector<std::pair<std::string, uint64_t>> FuncCounterMismatches;

lib/ProfileData/Coverage/CoverageMapping.cpp

@@ -207,8 +207,10 @@ Error CoverageMapping::loadFunctionRecord(
   else
     OrigFuncName = getFuncNameWithoutPrefix(OrigFuncName, Record.Filenames[0]);
 
-  // Don't load records for functions we've already seen.
-  if (!FunctionNames.insert(OrigFuncName).second)
+  // Don't load records for (filenames, function) pairs we've already seen.
+  auto FilenamesHash = hash_combine_range(Record.Filenames.begin(),
+                                          Record.Filenames.end());
+  if (!RecordProvenance[FilenamesHash].insert(hash_value(OrigFuncName)).second)
     return Error::success();
 
   CounterMappingContext Ctx(Record.Expressions);

test/tools/llvm-cov/multiple-objects.test

@@ -6,6 +6,11 @@ REPORT: Filename{{ +}}Regions{{ +}}Missed Regions{{ +}}Cover
 REPORT-NEXT: ---
 REPORT-NEXT: header.h{{ +}}25{{ +}}14{{ +}}44.00%
 
+# Make sure that both use_1.cc and use_2.cc have coverage reported.
+# Before https://reviews.llvm.org/D46478, only one of them used to be reported.
+REPORT-NEXT: use_1.cc{{ +}}1{{ +}}0{{ +}}100.00%
+REPORT-NEXT: use_2.cc{{ +}}2{{ +}}0{{ +}}100.00%
+
 Instructions for regenerating the test:
 
 clang -std=c++11 -mllvm -enable-name-compression=false -fprofile-instr-generate -fcoverage-mapping use_1.cc -o use_1

unittests/ProfileData/CoverageMappingTest.cpp

@@ -859,17 +859,34 @@ TEST_P(CoverageMappingTest, load_coverage_for_expanded_file) {
 TEST_P(CoverageMappingTest, skip_duplicate_function_record) {
   ProfileWriter.addRecord({"func", 0x1234, {1}}, Err);
 
+  // This record should be loaded.
   startFunction("func", 0x1234);
   addCMR(Counter::getCounter(0), "file1", 1, 1, 9, 9);
 
+  // This record should be loaded.
   startFunction("func", 0x1234);
   addCMR(Counter::getCounter(0), "file1", 1, 1, 9, 9);
+  addCMR(Counter::getCounter(0), "file2", 1, 1, 9, 9);
+
+  // This record should be skipped.
+  startFunction("func", 0x1234);
+  addCMR(Counter::getCounter(0), "file1", 1, 1, 9, 9);
+
+  // This record should be loaded.
+  startFunction("func", 0x1234);
+  addCMR(Counter::getCounter(0), "file2", 1, 1, 9, 9);
+  addCMR(Counter::getCounter(0), "file1", 1, 1, 9, 9);
+
+  // This record should be skipped.
+  startFunction("func", 0x1234);
+  addCMR(Counter::getCounter(0), "file1", 1, 1, 9, 9);
+  addCMR(Counter::getCounter(0), "file2", 1, 1, 9, 9);
 
   EXPECT_THAT_ERROR(loadCoverageMapping(), Succeeded());
 
   auto Funcs = LoadedCoverage->getCoveredFunctions();
   unsigned NumFuncs = std::distance(Funcs.begin(), Funcs.end());
-  ASSERT_EQ(1U, NumFuncs);
+  ASSERT_EQ(3U, NumFuncs);
 }
 
 // FIXME: Use ::testing::Combine() when llvm updates its copy of googletest.