[turbolizer] Add support for showing perf profiling information.

tools/turbolizer/README.md

+Turbolizer
+==========
+
+Turbolizer is a HTML-based tool that visualizes optimized code along the various
+phases of Turbofan's optimization pipeline, allowing easy navigation between
+source code, Turbofan IR graphs, scheduled IR nodes and generated assembly code.
+
+Turbolizer consumes .json files that are generated per-function by d8 by passing
+the '--trace-turbo' command-line flag.
+
+Host the turbolizer locally by starting a web server that serves the contents of
+the turbolizer directory, e.g.:
+
+    cd src/tools/turbolizer
+    python -m SimpleHTTPServer 8000
+
+Optionally, profiling data generated by the perf tools in linux can be merged
+with the .json files using the perf-turbo.py file included. The following
+command is an example of using the perf script:
+
+    perf script -i perf.data.jitted -s perf-turbo.py turbo-main.json
+
+The output of the above command is a json object that can be piped to a file
+which, when uploaded to turbolizer, will display the event counts from perf next
+to each instruction in the disassembly. Further detail can be found in the
+bottom of this document under "Using Perf with Turbo."
+
+Using the python interface in perf script requires python-dev to be installed
+and perf be recompiled with python support enabled. Once recompiled, the
+variable PERF_EXEC_PATH must be set to the location of the recompiled perf
+binaries.
+
+Graph visualization and manipulation based on Mike Bostock's sample code for an
+interactive tool for creating directed graphs. Original source is at
+https://github.com/metacademy/directed-graph-creator and released under the
+MIT/X license.
+
+Icons derived from the "White Olive Collection" created by Breezi released under
+the Creative Commons BY license.
+
+Using Perf with Turbo
+---------------------
+
+In order to generate perf data that matches exactly with the turbofan trace, you
+must use either a debug build of v8 or a release build with the flag
+'disassembler=on'. This flag ensures that the '--trace-turbo' will output the
+necessary disassembly for linking with the perf profile.
+
+The basic example of generating the required data is as follows:
+
+    perf record -k mono /path/to/d8 --turbo --trace-turbo --perf-prof main.js
+    perf inject -j -i perf.data -o perf.data.jitted
+    perf script -i perf.data.jitted -s perf-turbo.py turbo-main.json
+
+These commands combined will run and profile d8, merge the output into a single
+'perf.data.jitted' file, then take the event data from that and link them to the
+disassembly in the 'turbo-main.json'. Note that, as above, the output of the
+script command must be piped to a file for uploading to turbolizer.
+
+There are many options that can be added to the first command, for example '-e'
+can be used to specify the counting of specific events (default: cycles), as
+well as '--cpu' to specify which CPU to sample.