6 files changed, 39 insertions, 4 deletions
diff --git a/llvm/docs/CommandGuide/llvm-cov.rst b/llvm/docs/CommandGuide/llvm-cov.rst
index 71924e997d9..6e90760cbaf 100644
--- a/llvm/docs/CommandGuide/llvm-cov.rst
+++ b/llvm/docs/CommandGuide/llvm-cov.rst
@@ -150,6 +150,11 @@ OPTIONS
 
  Display the version of llvm-cov.
 
+.. option:: -x, --hash-filenames
+
+ Use md5 hash of file name when naming the coverage output files. The source
+ file name will be suffixed by ``##`` followed by MD5 hash calculated for it.
+
 EXIT STATUS
 ^^^^^^^^^^^
 
diff --git a/llvm/include/llvm/ProfileData/GCOV.h b/llvm/include/llvm/ProfileData/GCOV.h
index 27b76b577c1..9e2d27f083f 100644
--- a/llvm/include/llvm/ProfileData/GCOV.h
+++ b/llvm/include/llvm/ProfileData/GCOV.h
@@ -44,9 +44,10 @@ enum GCOVVersion { V402, V404, V704 };
 
 /// A struct for passing gcov options between functions.
 struct Options {
-  Options(bool A, bool B, bool C, bool F, bool P, bool U, bool L, bool N)
+  Options(bool A, bool B, bool C, bool F, bool P, bool U, bool L, bool N, bool X)
       : AllBlocks(A), BranchInfo(B), BranchCount(C), FuncCoverage(F),
-        PreservePaths(P), UncondBranch(U), LongFileNames(L), NoOutput(N) {}
+        PreservePaths(P), UncondBranch(U), LongFileNames(L), NoOutput(N),
+        HashFilenames(X) {}
 
   bool AllBlocks;
   bool BranchInfo;
@@ -56,6 +57,7 @@ struct Options {
   bool UncondBranch;
   bool LongFileNames;
   bool NoOutput;
+  bool HashFilenames;
 };
 
 } // end namespace GCOV
diff --git a/llvm/lib/ProfileData/GCOV.cpp b/llvm/lib/ProfileData/GCOV.cpp
index 41ea7555b9f..af4527024b4 100644
--- a/llvm/lib/ProfileData/GCOV.cpp
+++ b/llvm/lib/ProfileData/GCOV.cpp
@@ -18,6 +18,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/MD5.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <system_error>
@@ -686,7 +687,15 @@ std::string FileInfo::getCoveragePath(StringRef Filename,
   if (Options.LongFileNames && !Filename.equals(MainFilename))
     CoveragePath =
         mangleCoveragePath(MainFilename, Options.PreservePaths) + "##";
-  CoveragePath += mangleCoveragePath(Filename, Options.PreservePaths) + ".gcov";
+  CoveragePath += mangleCoveragePath(Filename, Options.PreservePaths);
+  if (Options.HashFilenames) {
+    MD5 Hasher;
+    MD5::MD5Result Result;
+    Hasher.update(Filename.str());
+    Hasher.final(Result);
+    CoveragePath += "##" + Result.digest().str().str();
+  }
+  CoveragePath += ".gcov";
   return CoveragePath;
 }
 
diff --git a/llvm/test/tools/llvm-cov/Inputs/test_hash.output b/llvm/test/tools/llvm-cov/Inputs/test_hash.output
new file mode 100644
index 00000000000..3f8b3f614d5
--- /dev/null
+++ b/llvm/test/tools/llvm-cov/Inputs/test_hash.output
@@ -0,0 +1,8 @@
+File 'srcdir/./nested_dir/../test.cpp'
+Lines executed:84.21% of 38
+srcdir/./nested_dir/../test.cpp:creating 'test.cpp##a806e5b3093cd6f683da88c0da150daf.gcov'
+
+File 'srcdir/./nested_dir/../test.h'
+Lines executed:100.00% of 1
+srcdir/./nested_dir/../test.h:creating 'test.h##0cbee7e2421fa4517420ac4f935620ca.gcov'
+
diff --git a/llvm/test/tools/llvm-cov/llvm-cov.test b/llvm/test/tools/llvm-cov/llvm-cov.test
index d460f37da2a..1ddbdad15cd 100644
--- a/llvm/test/tools/llvm-cov/llvm-cov.test
+++ b/llvm/test/tools/llvm-cov/llvm-cov.test
@@ -63,6 +63,11 @@ RUN: llvm-cov gcov -lp -gcno test_paths.gcno -gcda test_paths.gcda srcdir/../tes
 RUN: diff -aub test_paths.cpp.gcov srcdir#^#test_paths.cpp##srcdir#nested_dir#^#test.cpp.gcov
 RUN: diff -aub test_paths.h.gcov srcdir#^#test_paths.cpp##srcdir#nested_dir#^#test.h.gcov
 
+# Hash pathnames.
+RUN: llvm-cov gcov -x -gcno test_paths.gcno -gcda test_paths.gcda srcdir/../test_paths.cpp | diff -u test_hash.output -
+RUN: diff -aub test_paths.cpp.gcov test.cpp##a806e5b3093cd6f683da88c0da150daf.gcov
+RUN: diff -aub test_paths.h.gcov test.h##0cbee7e2421fa4517420ac4f935620ca.gcov
+
 # Function summaries. This changes stdout, but not the gcov files.
 RUN: llvm-cov gcov test.c -f | diff -u test_-f.output -
 RUN: diff -aub test_no_options.cpp.gcov test.cpp.gcov
diff --git a/llvm/tools/llvm-cov/gcov.cpp b/llvm/tools/llvm-cov/gcov.cpp
index 58ef2cf0219..8a00ff64711 100644
--- a/llvm/tools/llvm-cov/gcov.cpp
+++ b/llvm/tools/llvm-cov/gcov.cpp
@@ -124,6 +124,11 @@ int gcovMain(int argc, const char *argv[]) {
                                       "(requires -b)"));
   cl::alias UncondBranchA("unconditional-branches", cl::aliasopt(UncondBranch));
 
+  cl::opt<bool> HashFilenames("x", cl::Grouping, cl::init(false),
+                              cl::desc("Hash long pathnames"));
+  cl::alias HashFilenamesA("hash-filenames", cl::aliasopt(HashFilenames));
+
+
   cl::OptionCategory DebugCat("Internal and debugging options");
   cl::opt<bool> DumpGCOV("dump", cl::init(false), cl::cat(DebugCat),
                          cl::desc("Dump the gcov file to stderr"));
@@ -135,7 +140,8 @@ int gcovMain(int argc, const char *argv[]) {
   cl::ParseCommandLineOptions(argc, argv, "LLVM code coverage tool\n");
 
   GCOV::Options Options(AllBlocks, BranchProb, BranchCount, FuncSummary,
-                        PreservePaths, UncondBranch, LongNames, NoOutput);
+                        PreservePaths, UncondBranch, LongNames, NoOutput,
+                        HashFilenames);
 
   for (const auto &SourceFile : SourceFiles)
     reportCoverage(SourceFile, ObjectDir, InputGCNO, InputGCDA, DumpGCOV,