Truffle: introduce debug option to print the stack trace when transferring to the interpreter

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extra : rebase_source : 5e1ca3359e4b8d7c0ee906235630c8696f9cfe42
extra : amend_source : 3f0c3e58090c487a02b2b6c3e735f742f031b2f7
Fix operator precedence bug.

--HG--
extra : rebase_source : ca5659171f12b472dbac8d3d5a18dfe60d52ef44
Fix wrong NaN handling in FloatStamp.meet.

--HG--
extra : rebase_source : 970dcbb22a6424a097ff0d14ba8f5589e0ea7c54
consider equivalent phi inputs when simplfiying empty ifs