Right now coverage reports look like this:

...

602 861 int P2PSocketHostStunTcp::ProcessInput(char* input, int input_len) {
603 861   if (input_len < kPacketHeaderSize + kPacketLengthOffset)
604   6     return 0;
605 855
606 855   int pad_bytes;
607 855   int packet_size = GetExpectedPacketSize(
608 855       input, input_len, &pad_bytes);
609 855
610 855   if (input_len < packet_size + pad_bytes)
611 852     return 0;
612   3
613   3   // We have a complete packet. Read through it.
614   3   int consumed = 0;
...

Where the second column is number of hits. It might be cool if higher numbers would have some bright green highlight, and lower numbers would be more yellow-sh, an so on. So the column itself would be a bar showing "coverage density".

Shouldn't be hard to implement inside llvm-cov. We just have to find a good formula to make that look good, i.e. in the example above lines #604 and #612, #613, #614 should look almost the same, as they have relatively low coverage compared to other lines.