llvm-cov: When reading strings in gcov data, skip leading zeros

It seems that gcov, when faced with a string that is apparently zero
length, just keeps reading words until it finds a length it likes
better. I'm not really sure why this is, but it's simple enough to
make llvm-cov follow suit.

llvm-svn: 204881

1 files changed, 5 insertions, 2 deletions

diff --git a/llvm/include/llvm/Support/GCOV.h b/llvm/include/llvm/Support/GCOV.h
index aeac4555cee..902f2dbc83b 100644
--- a/llvm/include/llvm/Support/GCOV.h
+++ b/llvm/include/llvm/Support/GCOV.h
@@ -204,8 +204,11 @@ public:
   }
 
   bool readString(StringRef &Str) {
-    uint32_t Len;
-    if (!readInt(Len)) return false;
+    uint32_t Len = 0;
+    // Keep reading until we find a non-zero length. This emulates gcov's
+    // behaviour, which appears to do the same.
+    while (Len == 0)
+      if (!readInt(Len)) return false;
     Len *= 4;
     if (Buffer->getBuffer().size() < Cursor+Len) {
       errs() << "Unexpected end of memory buffer: " << Cursor+Len << ".\n";