Subzero: Generate a web page showing llvm2ice size breakdown.

Subzero: Generate a web page showing llvm2ice size breakdown.

"make -f Makefile.standalone bloat" generates a json file containing ./llvm2ice size data, and launches google-chrome on the output.

bloat.py is taken verbatim from https://github.com/martine/bloat/blob/master/bloat.py .

webtreemap.{js,css} are taken verbatim from https://github.com/martine/webtreemap .

llvm2ice.bloat.html is adapted from https://github.com/martine/webtreemap/blob/gh-pages/demo/demo.html .

BUG= none
R=jfb@chromium.org

Review URL: https://codereview.chromium.org/917203002