Hi John, > 2. Why does Vyacheslav suggest using --trace-hydrogen? Is that needed to see the disassembly?
I suggest passing --trace-hydrogen because it is needed to see the HIR - high-level intermediate representation (also known as hydrogen) - which is much easier to read then raw assembly. (for example Slides 38 on show HIR, not disassembly) Also if you --trace-hydrogen you can use a tool of mine called IRHydra[1] to inspect optimized code. It can show you source, HIR & disassembly all together[2]. [1] http://mrale.ph/irhydra/2 [2] http://imgur.com/HbOOXEM Vyacheslav Egorov On Wed, Oct 8, 2014 at 5:56 PM, John Feminella <[email protected]> wrote: > As an educational exercise, I'd like to inspect disassembled JS generated > by JS, and compare both the optimized and unoptimized versions to see what > changes and what doesn't. > > In Vyacheslav Egorov's JSConf 2012 excellent slides ( > http://s3.mrale.ph/jsconf2012.pdf) he recommends compiling V8 like so: > > ===== > make ia32.release objectprint=on \ > disassembler=on > > out/ia32.release/d8 --print-opt-code \ > --code-comments \ > --trace-hydrogen \ > test.js > ===== > > which will enable the disassembler for introspection by the curious. > > I'm having a little trouble understanding the current state of affairs, > though: > > 0. Is this the best way of doing things? How do I generate the > *unoptimized* JS versus the *optimized* JS for test.js in this example? > > 1. Are Hydrogen and Crankshaft still relevant? For example, my limited > understanding is that TurboFan will be replacing Hydrogen: > https://codereview.chromium.org/426233002 > Is there somewhere I can read about the relevance and lifecycle of > different pieces like Hydrogen and Crankshaft and how they play a role in > code generation/optimization? > > 2. Why does Vyacheslav suggest using --trace-hydrogen? Is that needed to > see the disassembly? > > Thanks for your help! > > best, > ~ jf > > -- > -- > v8-users mailing list > [email protected] > http://groups.google.com/group/v8-users > --- > You received this message because you are subscribed to the Google Groups > "v8-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- -- v8-users mailing list [email protected] http://groups.google.com/group/v8-users --- You received this message because you are subscribed to the Google Groups "v8-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
