On Thu, Dec 17, 2009 at 2:54 PM, Matt Fowles <[email protected]> wrote: > John~ > That depends on how you squint. I never bother with Janino's parser; I walk > my AST and generater a Janino AST and then cook that directly. I added the > method > > SimpleCompiler.cook(Java.CompilationUnit compilationUnit) > > to the API expressly for this purpose.
Ah. I can't run my compiler on the JVM until it's capable of compiling itself, so I need to generate Java code. > > > Matt > > On Thu, Dec 17, 2009 at 2:49 PM, John Cowan <[email protected]> wrote: >> >> On Thu, Dec 17, 2009 at 1:24 PM, Charles Oliver Nutter >> <[email protected]> wrote: >> > On Thu, Dec 17, 2009 at 12:17 PM, John Cowan <[email protected]> >> > wrote: >> >> I proposed a long time ago to add "goto" to Janino, which would remove >> >> a huge amount of the incentive to generate bytecode directly. The >> >> proposal was turned down, but the new moderator might be more >> >> receptive, especially if a patch was provided. (You can do a lot of >> >> what goto does with "do ... while (false)" and judicious use of break, >> >> but it's messy.) >> > >> > Ideally I should never have to worry about goto; I should be able to >> > feed something a Java/JVM-aware CFG and know it will produce the best >> > possible code for me. >> >> I don't understand this. Janino's input is Java 1.4 source code, not >> a CFG; it's an embeddable compiler. >> >> > >> >> I'm not sure that making Janino do its own optimizations is really a >> >> win: too-clever bytecode generators, as we know, can cause JITs to >> >> pessimize the code. But I'm willing to be convinced otherwise. >> > >> > I think this is true for small cases, but certainly not for large >> > ones. For example, sometimes it's just damned useful to be able to say >> > "inline this code everywhere...no really, just do it". Or in JRuby's >> > case, to be able to say "treat finals as really finals, finally!" and >> > not compile multiple accesses as multiple accesses. There's lots of >> > reasons why doing some up-front optimization can help, since even the >> > best JVM jits don't do *everything* for us. >> > >> > In JRuby's compiler, we're going to do a lot of this on a Ruby level >> > before feeding it to whatever bytecode generation, but ideally our >> > bytecode-generating backend would just translate our Ruby CFG into a >> > rough Java-like CFG and the backend will do additional optimization >> > passes to produce the best-possible bytecode. >> > >> > Another optimization a good compiler backend could do for us would be >> > generating smaller synthetic methods if basic blocks of code appeared >> > frequently in a very large body. Right now, javac and friends are >> > pretty dumb...you feed it a big chunk of code, it puts it into a big >> > method. But if it were smart about splitting up blocks into synthetic >> > submethods, we'd have mo' betta inlining possibilities, smaller units >> > of code, and generally better performance. >> > >> > There's a lot of opportunity here. >> > >> > - Charlie >> > >> > -- >> > >> > You received this message because you are subscribed to the Google >> > Groups "JVM Languages" group. >> > To post to this group, send email to [email protected]. >> > To unsubscribe from this group, send email to >> > [email protected]. >> > For more options, visit this group at >> > http://groups.google.com/group/jvm-languages?hl=en. >> > >> > >> > >> >> >> >> -- >> GMail doesn't have rotating .sigs, but you can see mine at >> http://www.ccil.org/~cowan/signatures >> >> -- >> >> You received this message because you are subscribed to the Google Groups >> "JVM Languages" group. >> To post to this group, send email to [email protected]. >> To unsubscribe from this group, send email to >> [email protected]. >> For more options, visit this group at >> http://groups.google.com/group/jvm-languages?hl=en. >> >> > > -- > > You received this message because you are subscribed to the Google Groups > "JVM Languages" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/jvm-languages?hl=en. > -- GMail doesn't have rotating .sigs, but you can see mine at http://www.ccil.org/~cowan/signatures -- You received this message because you are subscribed to the Google Groups "JVM Languages" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jvm-languages?hl=en.
